Original Article
Elastography Improves the Accuracy of Ultrasound in the Preoperative Assessment of abdominal wall endometriosis
Authors
S. Wozniak, P. Czuczwar, P. Szkodziak, E. Wozniakowska, P. Milart, M. Paszkowski, T. Paszkowski
Affiliation
3rd Chair and Deartment of Gynecology, Medical University of Lublin, Poland
Key words
Abstract
Zusammenfassung
"
!
!
Purpose: To assess the role of elastography in preoperative ultrasound assessment of abdominal wall endometriosis (AWE) location. Materials and Methods: 33 patients qualified for surgical excision of AWE were included in the study. Preoperative assessment of AWE was performed transabdominally on a Samsung Medison V20 Prestige with a transvaginal probe and Elastoscan® option. The following B-mode settings were used: focus set to the lower end of the lesion, gain adjusted to obtain best image quality, tissue harmonic imaging activated. For elastographic examinations the color map from red (soft) to purple (hard) and the alpha blend option (a blend of B-mode and elastographic image) were used. AWE location was first assessed by Bmode ultrasound as: superficial (located in SCT only; SCT visible between the fascia and the lesion; intact fascia), intermediate (located in SCT or in RAM; no subcutaneous or muscle tissue between the lesion and the fascia; fascia infiltrated); or deep (located in RAM; muscle tissue visible between the lesion and the fascia; fascia intact). Then the AWE location was assessed by alphablend elastography as: superficial (hard lesion in soft SCT; soft SCT between the fascia and the lesion; no hard areas on the fascia); intermediate (hard lesion in soft SCT or soft RAM; no soft subcutaneous or muscle tissue between the lesion and the fascia; hard areas on the fascia); or deep (hard lesion located in RAM; soft muscle tissue between the fascia and the lesion; no hard areas on the fascia). These findings were verified during surgery. The surgeons were blinded to the results of elastography. The influence of obesity on the accuracy of ultrasound and elastography in assessing the location of AWE was evaluated. Results: During surgery superficial AWE was found in 6, intermediate in 19 and deep in 8 patients. Preoperative ultrasound assessment was
Ziel: Bewertung der Rolle der Elastografie bei der präoperativen sonografischen Beurteilung der Lokalisation der AWE. Material und Methoden: 33 Patienten eigneten sich für eine chirurgische Entfernung der AWE und wurden in die Studie eingeschlossen. Die präoperative Beurteilung der AWE erfolgte transabdominal auf einem Samsung Medison V20 Prestige, mit transvaginaler Sonde und Elastoscan®-Option. Folgende B-Mode-Einstellungen wurden verwendet: Der Fokus wurde auf das untere Ende der Läsion gesetzt, der Gain wurde angepasst, um die beste Bildqualität zu erzeugen und das Tissue-Harmonic-Imaging wurde aktiviert. Für die elastografischen Untersuchungen wurde die Farbkarte von rot (weich) zu violett (hart) und die Alpha-Blending-Option (Mischung von B-Mode und elastografischem Bild) verwendet. Die Lokalisation der AWE wurde zuerst mittels B-Mode-Sonografie bewertet als: Oberflächlich (Lokalisation nur im SCT, SCT zwischen Faszie und Herd sichtbar, intakte Faszie), intermediär (Lokalisation im SCT oder RAM, Fehlen von SCT oder Muskelgewebe zwischen Herd und Faszie, infiltrierte Faszie) oder tief (Lokalisation im RAM, sichtbares Muskelgewebe zwischen Herd und Faszie sichtbar, intakte Faszie). Anschließende Beurteilung des AWE-Herd durch Alpha-Blend-Elastografie als: Oberflächlich (harter Herd im weichen SCT, weiches SCT zwischen Faszie und Herd; keine harten Bereiche auf der Faszie), intermediär (harter Herd im weichen SCT oder weichen RAM; Fehlen von weichem SCT oder Muskelgewebe zwischen Herd und Faszie; harte Bereiche auf der Faszie) oder tief (harter Herd mit Lokalisation im RAM; weiches Muskelgewebe zwischen Faszie und Herd; keine harten Bereiche auf der Faszie). Diese Befunde wurden bei der Operation verifiziert, die Chirurgen wurden verblindet in Bezug auf die Elastografie-Er-
● ultrasound ● endometriosis ● elastography " "
received accepted
27.1.2014 4.12.2014
Bibliography DOI http://dx.doi.org/ 10.1055/s-0034-1398834 Published online: 2015 Ultraschall in Med © Georg Thieme Verlag KG Stuttgart · New York · ISSN 0172-4614 Correspondence Dr. Slawomir Wozniak 3rd Chair and Deartment of Gynecology, Medical University of Lublin Jaczewskiego 8 20–954 Lublin Poland Tel.: ++ 48/5 02 07 38 33 Fax: ++ 48/81/7 24 48 48 [email protected]
Wozniak S et al. Elastography Improves the … Ultraschall in Med
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Die Elastografie verbessert die Genauigkeit des Ultraschalls bei der präoperativen Beurteilung der Endometriose der Bauchwand
correct in 33.3 % of cases, while adding the elastography option improved the accuracy of AWE location assessment to 87.9 % (p < 0.05). The diagnostic accuracy of ultrasound alone, but not with the elastography option, was significantly decreased in the preoperative assessment of AWE location in overweight and obese patients. 4 patients required implantation of a mesh. In all cases the pathological examination confirmed the diagnosis of AWE. Conclusion: Elastography significantly improved the accuracy of ultrasound in evaluating the depth of infiltration of AWE, is not affected by increased BMI, and should be considered in patients qualified for surgical treatment of AWE.
gebnisse. Auch der Einfluss von Adipositas auf die Genauigkeit des Ultraschalls und der Elastografie bei der Beurteilung der Lokalisation der AWE wurde untersucht. Ergebnisse: Bei der Operation wurde die AWE bei 6 als oberflächlich, bei 19 als intermediär und bei 8 Patienten als tief diagnostiziert. Die präoperative Ultraschallbeurteilung war in 33,3 % der Fälle richtig, wobei die Elastografie-Option die Genauigkeit der Lokalisation der AWE auf 87,9 % (p < 0.05). Die diagnostische Genauigkeit des Ultraschalls alleine, ohne Elastografie-Option führte zu einem statistisch signifikanten Rückgang der Genauigkeit der Lokalisation der AWE bei übergewichtigen und adipösen Patienten. Bei 4 Patienten war die Implantation eines Netzes erforderlich. In allen Fällen wurde die AWE-Diagnose durch die pathologische Untersuchung bestätigt. Schlussfolgerung: Die Elastografie verbesserte die Genauigkeit der Sonografie signifikant in Bezug auf die Beurteilung der Infiltrationstiefe der AWE. Sie wird nicht von einem erhöhten BMI beeinflusst und kann bei Patienten, die für eine chirurgische Behandlung der AWE vorgesehen sind, zum Einsatz kommen.
Endometriosis is defined as the presence of endometrial glands and stroma outside the uterine cavity [1]. Typically, endometrial implants are located in the minor pelvis (ovaries, pelvic peritoneum, rectovaginal septum, etc.), but can also be found in other locations such as the brain, lungs and abdominal wall (subcutaneous tissue and abdominal wall muscles). Abdominal wall endometriosis (AWE) usually develops in the region of a previous cesarean section scar, but has also been described after hysterectomies and laparoscopies or even without previous surgery [2, 3]. The risk of AWE after a cesarean section is estimated at 0.03 – 1 % [4]. Typical symptoms of AWE include a palpable mass near a surgical scar and cyclic pain associated with menses. In most cases a thorough history and physical examination are sufficient to make a correct diagnosis [5]. The treatment of choice of AWE is surgical excision, and the diagnosis is confirmed by a pathological examination. AWE is frequently located in the subcutaneous tissue, but can also infiltrate the abdominal rectus muscle and/or its fascia, making the surgery more difficult and sometimes requiring implantation of a mesh [6]. Therefore, precise preoperative assessment is important when planning surgical treatment of AWE. Considering the fact that during ultrasound examination AWE lesions appear to have ill-defined, blurred, often spiculated margins [6, 7], it may be difficult to evaluate AWE infiltration by conventional B-mode ultrasound alone. There are no reports evaluating the usefulness of other imaging techniques (CEUS, MRI) in the preoperative assessment of AWE location. Elastography is a novel ultrasound-based imaging modality that assesses the elasticity of visualized tissues [8, 9]. One of the many elastography methods is strain elastography, based on the phenomenon that after applying pressure with the probe the strain of hard tissues is lower than that of soft tissues. Gradient values of strain are visualized on a color map, representing the stiffness of the examined area. The use of elastography in the imaging of hard masses in softer tissues for describing their location and size and selecting biopsy regions has been described in breast, prostate, thyroid and other tumors [10 – 15]. The application of elastography in obstetrics and gynecology has also been reported, for instance in predicting the success of the induction of labor [16, 17] and for the differential diagnosis of endometrial pathologies [18].
The objective of this prospective observational study was to assess the potential role of elastography in the preoperative ultrasound assessment of AWE location.
Wozniak S et al. Elastography Improves the … Ultraschall in Med
Materials and Methods !
Patients with suspected AWE (based on medical history, signs and symptoms: palpable mass in the region of C-section scar; cyclic or continuous pain) in the previous C-section scar were qualified for initial B-mode ultrasound scan. Only patients with AWE visible on B-mode ultrasound were asked to participate in the study and qualified for surgical excision of AWE. Data on patient’s age, BMI and obstetrical history was collected. During preoperative assessment each patient underwent a two-stage ultrasound evaluation of AWE size (maximal diameter) and location: first only by B-mode ultrasound and then in the alpha-blend elastography (combined Bmode and elastography color map). During surgery the location of " Fig. 1). AWE was verified and the lesions were measured again (● All lesions were sent for histopathological examination to confirm the diagnosis. All patients presented for a control examination in our department one month after surgery to receive their histopathological results and to assess the postoperative course. All ultrasound examinations were performed transabdominally by one experienced sonographer (SW; 20 years of experience in obstetrics and gynecology ultrasound, 5 years of elastography experience) on a Samsung Medison V20 Prestige equipped with a transvaginal (4 – 9 MHz) convex probe and Elastoscan® option. Considering the greater availability of the transvaginal probe in gynecological departments, we have decided to use only the transvaginal probe instead of the linear transabdominal probe. In all cases the following B-mode settings were used: focus set on the lower end of the lesion, gain adjusted to obtain best image quality, tissue harmonic imaging activated. Additionally, the vascularization (number of blood vessels) of AWE lesions was assessed using the power Doppler option with a pulse repetition frequency of 600 Hz. After visualizing the AWE lesion in B-mode ultrasound, the probe was positioned centrally over the lesion and the Elastoscan option was activated. The probe was held still without any additional pressure for about 15 seconds. The elastographic image was generated by the patient’s breathing movements and arterial
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Original Article
pulsation. The elasticity of tissues was visualized using a color map from red (soft) to purple (hard). Alpha-blend elastography was used where the B-mode image was blended with the elastographic color map, which depicted both the hyperechogenic fascia and the " Fig. 2). After freezing the image, the hard (purple) AWE nodule (●
Fig. 1 Flowchart of the study design Abb. 1 Flussdiagramm des Studiendesigns.
stored cine loop was reviewed slowly to select the most reproducible frame. The location of AWE was described similarly to Savelli et al. as superficial (S; in subcutaneous tissue only, above fascia), intermediate (I; infiltrating the abdominal rectus muscle fascia) and deep (D; in the abdominal rectus muscle, below fascia) [6] " Fig. 3). The criteria for B-mode ultrasound assessment of AWE (● location were: superficial (located in the subcutaneous tissue only; subcutaneous tissue visible between the fascia and the lesion; intact fascia), intermediate (located in the subcutaneous tissue or in the rectus abdominis muscle; no subcutaneous or muscle tissue between the lesion and the fascia; fascia infiltrated); or deep (located in the rectus abdominis muscle; muscle tissue visible between the lesion and the fascia; fascia intact). The criteria for the alpha-blend elastography assessment of AWE location were: superficial (hard lesion located in soft subcutaneous tissue; soft subcutaneous tissue between the fascia and the lesion; no hard areas on the fascia); intermediate (hard lesion in the soft subcutaneous tissue or soft rectus abdominis muscle; no soft subcutaneous or muscle tissue between the lesion and the fascia; hard areas on the fascia); or deep (hard lesion located in the soft rectus abdominis muscle; soft muscle tissue between the fascia and the lesion; no hard areas on the fascia). All surgical interventions and intraoperative assessment of AWE size and location were performed by PC, PM and PS, who were blinded to the results of imaging examinations. The measurements were performed using a sterile ruler after dissecting the lesion and finding the largest macroscopic diameter (including the spiculated margins). To evaluate the possible influence of obesity on the accuracy of ultrasound and elastography in assessing the location of AWE, patients were stratified on the basis of BMI to overweight/obese (BMI > 25) and with normal BMI (BMI ≤ 25). The study protocol was accepted by a local Bioethics committee. All patients signed an informed consent to participate in the study. Statistical analysis was performed using Statistica software (version 10, Statsoft, USA). Maximal AWE diameters assessed by all methods were first compared by Friedman ANOVA and then by
Fig. 2 A B-mode ultrasound image of AWE. The lesion appears to have regular margins, and the fascia (arrow) appears intact. B Elastographic image of the same AWE lesion. The lesion seems larger, its margins appear irregular, spiculated and infiltrating the fascia (arrow). C Resected surgical specimen shows irregular, spiculated margins (arrows). D A fascial defect after resection of AWE is shown (arrow). Sometimes a non-resorbable mesh may be required to fix the defect. Abb. 2 A B-Mode-US einer AWE. Der Herd scheint gleichmäßige Ränder zu haben, die Faszie (Pfeil) erscheint intakt. B Elastografisches Bild desselben AWE-Herdes. Der Herd erscheint größer, dessen Ränder erscheinen irregulär, nadelartig und infiltrieren die Faszie (Pfeil). C Die entnommene chirurgische Probe zeigt irreguläre, nadelartige Ränder (Pfeile). D Eine Schädigung der Faszie nach Resektion der AWE wird gezeigt (Pfeil). Manchmal kann ein nicht-resorbierbares Netz nötig sein, um den Schaden zu beheben.
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Original Article
Original Article
Characteristics of the studied population.
age (years; median, range)
30
20 – 42
time from C/S (months; median, range)
23
14 – 50
BMI (median, range) no. of previous C/S (n, %)
symptoms suggestive of deep endometriosis (n, %)
Fig. 3 The location of AWE: superficial (S; in subcutaneous tissue only, above fascia), intermediate (I; infiltrating the abdominal rectus muscle fascia) and deep (D; in the abdominal rectus muscle, below fascia). Abb. 3 Die Lokalisierung der AWE: Oberflächlich (S; nur im subkutanen Gewebe, oberhalb der Faszie), intermediär (I; Infiltration der Faszie des M. rectus abdominis) und tief (D; im M. rectus abdominis, unterhalb der Faszie).
Wilcoxon signed rank test. The accuracy of B-mode ultrasound and alpha-blend elastography AWE location assessment was compared using the McNemar’s test. The accuracy of B-mode ultrasound and alpha-blend elastography in patients with normal and abnormal BMI was compared using the χ2 test. P-values < 0.05 were considered significant.
Results
22,9
17.9 – 34.1
1
22
66.7 %
2
10
30.3 %
3
1
3%
dysmenorrhea
20
60.6 %
dyspareunia
12
36.4 %
" Fig. 4). The values obtained during alpha-blend elasp < 0.001) (● tography and surgical assessment were not significantly different " Fig. 4). (p = 0.54) (● Influence of BMI on the performance of B-mode ultrasound and alpha-blend elastography in the preoperative assessment of AWE " Table 3, 4. The accuracy of B-mode ultrasound in evalis shown● uating AWE location was significantly worse in overweight and obese patients in comparison to patients with normal BMI (7.7 % " Table 3). The accuracy of alpha-blend elasvs 50 %; p = 0.012) (● tography in evaluating AWE location did not differ between normal BMI and overweight/obese patients (90 % vs. 84.6 %; p = 0.64) " Table 4). (● In 21 (63.6 %) AWE lesions, no blood flow was observed, 1 blood vessel was visible in 5 (15.2 %) cases, 2 blood vessels in 4 (12.1 %) cases and 3 or more blood vessels in 3 (9.1 %) cases. In 4 patients (12.1 %) the fascial defect required implanting a mesh. No complications occurred during the surgeries. In all cases the postoperative course was not complicated. During the data collection period, none of the patients had recurrence of AWE symptoms (follow-up 6 – 24 months). In all cases the pathological examination confirmed the diagnosis and complete removal of AWE.
!
The initial B-mode ultrasound scan was performed in 36 patients with suspected AWE. In 33 patients AWE was visualized and " Fig. 2). these patients were included in the study (● The clinical characteristics of the studied 33 patients are shown in ●" Table 1. A detailed description of the patients’ BMI, AWE symptoms and results of B-mode ultrasound, alpha-blend elastogra" Taphy, and surgical evaluation of AWE lesions is presented in ● ble 2. In the studied group 39.4 % of patients were overweight/ obese, a palpable mass was present in 87.9 % cases, 66.7 % of patients reported cyclic pain, 21.2 % reported continuous pain and 12.1 % had no pain at all. During surgery the location of AWE was assessed as superficial in 6 patients (18.2 %), intermediate (infiltrating fascia) in 19 patients " Table 2). Preoperative (57.6 %) and deep in 8 patients (24.2 %) (● B-mode ultrasound assessment was correct (concordant with surgical evaluation) in 33.3 % of cases, while alpha-blend elastography allowed a more accurate evaluation of AWE location " Table 2). The McNemar’s test showed (87.9 % of correct cases) (● that the accuracy of alpha-blend elastography in assessing AWE location was significantly better in comparison to B-mode ultrasound (p < 0.001). Friedman ANOVA showed a significant difference between Bmode ultrasound, alpha-blend elastography and surgical measurements (p < 0.001). Median maximum diameter of the AWE lesions estimated by B-mode ultrasound was 27 mm (range 5 – 36 mm) and was significantly lower than the median maximum diameters assessed by alpha-blend elastography (30 mm; range 8 – 42; p < 0.001) and during surgery (30 mm; range 8 – 41; Wozniak S et al. Elastography Improves the … Ultraschall in Med
Discussion !
The median maximum AWE diameter observed in our study is consistent with the literature. Horton et al. in a review of 445 cases of AWE calculated the mean largest dimension to be 27 mm (95 % CI, 21 – 32 mm), with no statistical differences between included studies [3]. Interestingly, in our study the diameters obtained by B-mode ultrasound were significantly lower than those obtained by alpha-blend elastography or during surgery. It may point to the fact that alpha-blend elastography improves the accuracy of Bmode ultrasound in measuring AWE, probably due to better visualization of infiltrating margins of AWE lesions. However, it has to be stated that while surgical assessment may be considered a “gold standard” in evaluating AWE location, its accuracy in measuring AWE size may be questionable. The infiltrating, irregular, spiculated margins of AWE lesions are difficult to measure during " Fig. 1). macroscopic assessment (● The majority of examined AWE lesions showed no blood flow or only 1 – 2 vessels. These results are similar to those obtained by Savelli et al. 2012, who found ≤ 3 blood vessels in all 21 AWE lesions examined [6]. Therefore, it is unlikely that the classic Doppler examination may play a role in preoperative assessment of AWE location. Correct preoperative assessment of AWE location undoubtedly is important. Small AWE lesions located in the subcutaneous tissue only are usually easy to remove. Infiltration of the rectus muscle fascia or the muscle layer itself makes the surgery much more difficult, and may require a wider laparotomy
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Table 1
Original Article
BMI
symptoms of AWE palpable
pain
mass
preoperative AWE location assessment B-mode ultra-
alpha blend elasto-
sound
graphy
AWE location – surgical findings
1
N
YES
CYC
C
C
S
2
O
YES
CON
IC
C
I
3
N
YES
NO
IC
C
D
4
O
NO
CYC
IC
C
D
5
N
YES
CYC
C
C
I
6
N
YES
CON
C
C
S
7
N
YES
CON
IC
C
I
8
N
YES
CYC
C
C
D
9
N
YES
CYC
IC
IC
I
10
N
YES
CYC
C
C
D
11
N
YES
NO
IC
C
I
12
O
NO
CYC
IC
C
I
13
N
YES
CON
IC
IC
I
14
O
YES
CYC
IC
C
I
15
O
YES
NO
IC
C
I
16
O
NO
CYC
IC
C
I
17
O
YES
CYC
IC
C
I
18
N
YES
CYC
C
C
S
19
O
YES
CYC
IC
IC
I
20
N
YES
NO
C
C
S
21
O
YES
CON
IC
C
I
22
N
YES
CYC
IC
C
D
23
N
YES
CYC
IC
C
I
24
N
YES
CON
C
C
I
25
O
YES
CYC
IC
C
I
26
O
YES
CYC
IC
C
I
27
N
YES
CYC
C
C
S
28
N
YES
CYC
C
C
I
29
O
YES
CYC
C
C
S
30
O
NO
CON
IC
IC
D
31
N
YES
CYC
IC
C
D
32
N
YES
CYC
IC
C
I
33
N
YES
CYC
IC
C
D
Table 2 Relationship of BMI, signs, symptoms, B-mode ultrasound and alpha-blend elastography findings and surgical diagnosis.
AWE – abdominal wall endometriosis; N – normal BMI; O – overweight/obese; CYC – cyclic pain; CON – continuous pain; C – correct; IC – incorrect; S – superficial; I – intermediate; D – deep
Fig. 4 Maximum diameters of AWE lesions assessed by B-mode ultrasound, alpha-blend elastography and during surgery. AWE – abdominal wall endometriosis; * p < 0.05; NS – not significant Abb. 4 Maximale Durchmesser der AWE-Herde, bestimmt durch B-Bild Sonografie, Alpha-BlendElastografie und bei der Operation. AWE – abdominale Endometriose der Bauchwand; * p < 0,05; NS – nicht signifikant
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patient
Table 3 Accuracy of the B-mode ultrasound assessment of AWE location in overweight/obese and normal BMI patients.
incorrect B-mode
correct B-mode
statistical
ultrasound
ultrasound
analysis
assessment
assessment
normal BMI
10 (50 %)
10 (50 %)
overweight/ obese
12 (92 %)
1 (8 %)
χ2 = 6.35 p = 0.012
Table 4 Accuracy of the alpha-blend elastography assessment of AWE location in overweight/obese and normal BMI patients.
incorrect alpha-
correct alpha-
statistical
blend elastography
blend elasto-
analysis
assessment (n)
graphy assessment (n)
normal BMI
2 (10 %)
18 (90 %)
overweight/ obese
2 (15 %)
11 (85 %)
χ2 = 0.21 p = 0.64
and sometimes implantation of a mesh. Therefore, knowledge of AWE location may be helpful in planning the surgery, choosing the reference hospital and surgical team, predicting the time of surgery and securing additional material, such as a mesh. For example, in the study by Francica et al., repair of the fascia and/or abdominal rectus muscle was necessary in 5 out of 12 patients (41.6 %) [5], while in our group in 81.8 % of patients at least a minor infiltration of the fascia and/or muscle was present. Bektas et al. implanted a mesh in 4 out of 40 patients (10 %) operated on because of AWE [19]. Similarly, in our study 12.1 % of patients required implantation of a mesh. That is why it is important to differentiate various locations of AWE during preoperative assessment. In a recent report AWE location was described as superficial in 57 % of patients, intermediate in 24 % and deep in 19 % [6]. However, these findings were based only on ultrasound and were not verified by surgery. Interestingly, the results of the B-mode ultrasound assessment of AWE location in our study were similar, with the majority of lesions described as superficial (45.5 %) and a smaller percentage as intermediate (18.2 %) and deep (33.3 %). Out of 16 cases in which AWE was described as superficial on the basis of B-mode ultrasound, only 6 were confirmed during surgery, while in 10 cases infiltration of the rectus muscle sheath was observed. After surgical assessment only 18.2 % cases were found to be superficial, 63.5 % were intermediate and 24.3 % were deep. These results suggest that infiltration of the fascia may be much more common than expected after B-mode ultrasound examination. Our results clearly show that preoperative B-mode ultrasound assessment of AWE location is not reliable with an overall accuracy of 33.3 %, which was significantly worse than the accuracy of alpha-blend elastography (87.9 %). All cases of incorrect B-mode ultrasound evaluation occurred in intermediate and deep AWE lesions. As expected, B-mode ultrasound examination of superficial lesions was easier and was correct in all 5 cases of superficial AWE. When using the alpha-blend elastography mode, the fascia appears as a hyperechogenic line. AWE lesions appear as hard (purple) nodules and can be distinguished from softer surrounding tissues, their correspondence to the fascia is also visualized
Wozniak S et al. Elastography Improves the … Ultraschall in Med
" Fig. 1), which may explain the overall performance of alpha(● blend elastography. The major disadvantage of alpha-blend elastography is that due to the presence of many techniques and processing algorithms for producing and displaying elastographic images, the findings may be specific to a particular system [20]. In our study, the software (Elastoscan) did not require the use of compression/decompression cycles, which may decrease the interobserver variability [17]. In our study the accuracy of B-mode ultrasound in assessing AWE location was surprisingly low. Unfortunately, we did not identify any studies comparing the ultrasound assessment of AWE location with surgical findings. However, some authors evaluated the accuracy of ultrasound in differential diagnosis of AWE lesions and acquired disappointing results. In the study by Bektas et al., preoperative ultrasound diagnosis was correct in 47.5 % of cases [19], while in the study by Ozel et al. ultrasound provided conclusive information only in 11.1 % patients [21]. It seemed reasonable to assume that preoperative B-mode ultrasound assessment of AWE lesions may be impaired in overweight and obese patients due to increased thickness of the subcutaneous tissue. To the best of our knowledge, this is the first report addressing this issue. In our group 13 patients were overweight or obese and B-mode ultrasound AWE location assessment was correct in only 1 case (7.7 %). During surgery in overweight/obese patients, the majority of AWE lesions were found to be intermediate or deep (12 cases), while only one was superficial. Interestingly, B-mode ultrasound assessment was correct only in the case of superficial AWE, which shows that B-mode ultrasound evaluation of deeper layers in overweight/obese patients is, as expected, not satisfactory. Moreover, B-mode ultrasound AWE location assessment was significantly better in patients with a nor" Table 3), which mal BMI than in overweight/obese patients (● confirms the hypothesis that increased BMI impairs the performance of B-mode ultrasound in evaluating AWE. On the other hand, since elastography is an imaging modality designed specifically to differentiate soft and hard tissues, it seemed a perfect technique to distinguish soft subcutaneous tissue from hard AWE lesions in overweight/obese patients. We did indeed observe that increased BMI did not affect the performance of al" Tapha-blend elastography in assessing the location of AWE (● ble 4). Therefore, we can state that the accuracy of B-mode ultrasound in assessing AWE location is greatly diminished by increasing BMI, while alpha-blend elastography remains independent of this factor. Even though the use of magnetic resonance imaging (MRI) and computed tomography (CT) in diagnosing AWE has been described by some authors [22, 23], these techniques do not seem to provide additional information to a properly performed ultrasound examination and are unlikely to modify the treatment strategy [7]. In a recent study Ozel et al., reported that CT did not provide conclusive information in any of the 4 cases in which it was performed, while MRI provided conclusive information in only 4 of 8 cases [21]. However, it has to be stressed that MRI and CT were used in these studies for the differential diagnosis of abdominal masses and not for the assessment of AWE location. Moreover, many groups state that the typical history, symptoms and physical examination are sufficient to make a diagnosis of AWE [5, 24] and this approach is used in our department as well. Therefore, performing additional diagnostic procedures, such as MRI and CT, does not seem necessary and may only impair the overall cost-effectiveness. Preoperative alpha-blend elas-
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Original Article
tography examination may provide reliable assessment of AWE lesion location, which is important in planning surgical treatment.
Conclusion !
1. Alpha-blend elastography improves the performance of Bmode ultrasound in the preoperative assessment of AWE location. 2. The accuracy of alpha-blend elastography in the preoperative assessment of AWE location is not decreased in overweight and obese patients. 3. Alpha-blend elastography provides important information in the preoperative assessment of patients qualified for surgical treatment of AWE.
References 01 Nisolle M, Alvarez ML, Colombo M et al. Pathogenesis of endometriosis. Gynecol Obstet Fertil 2007; 35: 898 – 903 02 Elm MK, Twede JV, Turiansky GW. Primary cutaneous endometriosis of the umbilicus: A case report. Cutis 2008; 81: 124 – 126 03 Horton JD, Dezee KJ, Ahnfeldt EP et al. Abdominal wall endometriosis: a surgeon's perspective and review of 445 cases. Am J Surg 2008; 196: 207 – 212 04 Nominato NS, Prates LFVS, Lauar I et al. Caesarean section greatly increases risk of scar endometriosis. Eur J Obstet Gynecol 2010; 152: 83 – 85 05 Francica G. Sonographic features of abdominal wall endometrioma. Am J Roentgenol Am J Roentgenol 2006; 187: W127; author reply W128 06 Savelli L, Manuzzi L, Di Donato N et al. Endometriosis of the abdominal wall: ultrasonographic and Doppler characteristics. Ultrasound Obstet Gynecol 2012; 39: 336 – 340 07 Francica G, Giardiello C, Angelone G et al. Abdominal wall endometriomas near cesarean delivery scars: sonographic and color doppler findings in a series of 12 patients. J Ultrasound Med 2003; 22: 1041 – 1047 08 Bamber J, Cosgrove D, Dietrich CF et al. EFSUMB guidelines and recommendations on the clinical use of ultrasound elastography. part 1: Basic principles and technology. Ultraschall in Med 2013; 34: 169 – 184
09 Cosgrove D, Piscaglia F, Bamber J et al. EFSUMB guidelines and recommendations on the clinical use of ultrasound elastography.part 2: Clinical applications. Ultraschall in Med 2013; 34: 238 – 253 10 Wojcinski S, Farrokh A, Weber S et al. Multicenter study of ultrasound real-time tissue elastography in 779 cases for the assessment of breast lesions: Improved diagnostic performance by combining the BI-RADS (R)-US classification system with sonoelastography. Ultraschall in Med 2010; 31: 484 – 491 11 Kumm T, Szabunio M. Elastography for the characterization of breast lesions: initial clinical experience. Cancer Control 2010; 17: 156 – 161 12 Rago T, Santini F, Scutari M et al. Elastography: new developments in ultrasound for predicting malignancy in thyroid nodules. J Clin Endocrinol Metab 2007; 92: 2917 – 2922 13 Aigner F, Mitterberger M, Rehder P et al. Status of transrectal ultrasound imaging of the prostate. J Endourol 2010; 24: 685 – 691 14 Kato K, Sugimoto H, Kanazumi N et al. Intra-operative application of real-time tissue elastography for the diagnosis of liver tumors. Liver Int 2008; 28: 1264 – 1271 15 Bhatia K, Rasalkar D, Lee Y et al. Evaluation of real-time qualitative sonoelastography of focal lesions in the parotid and submandibular glands: applications and limitations. Eur Radiol 2010; 20: 1958 – 1964 16 Preis K, Swiatkowska-Freund M, Pankrac Z. Elastography in the examination of the uterine cervix before labor induction. Ginekol Pol 2010; 81: 757 – 761 17 Swiatkowska-Freund M, Preis K. Elastography of the uterine cervix: implications for success of induction of labor. Ultrasound Obstet Gynecol 2011; 38: 52 – 56 18 Preis K, Zielinska K, Swiatkowska-Freund M et al. The role of elastography in the differential diagnosis of endometrial pathologies – preliminary report. Ginekol Pol 2011; 82: 494 – 497 19 Bektaş H, Bilsel Y, Sari YS et al. Abdominal wall endometrioma; a 10year experience and brief review of the literature. J Surg Res 2010; 164: e77 – e81 20 Drakonaki EE, Allen GM, Wilson DJ. Ultrasound elastography for musculoskeletal applications. Br J Radiol 2012; 85: 1435 – 1445 21 Ozel L, Sagiroglu J, Unal A et al. Abdominal wall endometriosis in the cesarean section surgical scar: a potential diagnostic pitfall. J Obstet Gynaecol Res 2012; 38: 526 – 530 22 Amato M, Levitt R. Abdominal wall endometrioma: CT findings. J Comput Assist Tomogr 1984; 8: 1213 – 1214 23 Wolf GC, Kopecky KK. MR imaging of endometriosis arising in cesarean section scar. J Comput Assist Tomogr 1989; 13: 150 – 152 24 Nirula R, Greaney GC. Incisional endometriosis: an underappreciated diagnosis in general surgery. J Am Coll Surg 2000; 190: 404 – 407
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Original Article
Elastography Improves the Accuracy of Ultrasound in the Preoperative Assessment of abdominal wall endometriosis
Authors
S. Wozniak, P. Czuczwar, P. Szkodziak, E. Wozniakowska, P. Milart, M. Paszkowski, T. Paszkowski
Affiliation
3rd Chair and Deartment of Gynecology, Medical University of Lublin, Poland
Key words
Abstract
Zusammenfassung
"
!
!
Purpose: To assess the role of elastography in preoperative ultrasound assessment of abdominal wall endometriosis (AWE) location. Materials and Methods: 33 patients qualified for surgical excision of AWE were included in the study. Preoperative assessment of AWE was performed transabdominally on a Samsung Medison V20 Prestige with a transvaginal probe and Elastoscan® option. The following B-mode settings were used: focus set to the lower end of the lesion, gain adjusted to obtain best image quality, tissue harmonic imaging activated. For elastographic examinations the color map from red (soft) to purple (hard) and the alpha blend option (a blend of B-mode and elastographic image) were used. AWE location was first assessed by Bmode ultrasound as: superficial (located in SCT only; SCT visible between the fascia and the lesion; intact fascia), intermediate (located in SCT or in RAM; no subcutaneous or muscle tissue between the lesion and the fascia; fascia infiltrated); or deep (located in RAM; muscle tissue visible between the lesion and the fascia; fascia intact). Then the AWE location was assessed by alphablend elastography as: superficial (hard lesion in soft SCT; soft SCT between the fascia and the lesion; no hard areas on the fascia); intermediate (hard lesion in soft SCT or soft RAM; no soft subcutaneous or muscle tissue between the lesion and the fascia; hard areas on the fascia); or deep (hard lesion located in RAM; soft muscle tissue between the fascia and the lesion; no hard areas on the fascia). These findings were verified during surgery. The surgeons were blinded to the results of elastography. The influence of obesity on the accuracy of ultrasound and elastography in assessing the location of AWE was evaluated. Results: During surgery superficial AWE was found in 6, intermediate in 19 and deep in 8 patients. Preoperative ultrasound assessment was
Ziel: Bewertung der Rolle der Elastografie bei der präoperativen sonografischen Beurteilung der Lokalisation der AWE. Material und Methoden: 33 Patienten eigneten sich für eine chirurgische Entfernung der AWE und wurden in die Studie eingeschlossen. Die präoperative Beurteilung der AWE erfolgte transabdominal auf einem Samsung Medison V20 Prestige, mit transvaginaler Sonde und Elastoscan®-Option. Folgende B-Mode-Einstellungen wurden verwendet: Der Fokus wurde auf das untere Ende der Läsion gesetzt, der Gain wurde angepasst, um die beste Bildqualität zu erzeugen und das Tissue-Harmonic-Imaging wurde aktiviert. Für die elastografischen Untersuchungen wurde die Farbkarte von rot (weich) zu violett (hart) und die Alpha-Blending-Option (Mischung von B-Mode und elastografischem Bild) verwendet. Die Lokalisation der AWE wurde zuerst mittels B-Mode-Sonografie bewertet als: Oberflächlich (Lokalisation nur im SCT, SCT zwischen Faszie und Herd sichtbar, intakte Faszie), intermediär (Lokalisation im SCT oder RAM, Fehlen von SCT oder Muskelgewebe zwischen Herd und Faszie, infiltrierte Faszie) oder tief (Lokalisation im RAM, sichtbares Muskelgewebe zwischen Herd und Faszie sichtbar, intakte Faszie). Anschließende Beurteilung des AWE-Herd durch Alpha-Blend-Elastografie als: Oberflächlich (harter Herd im weichen SCT, weiches SCT zwischen Faszie und Herd; keine harten Bereiche auf der Faszie), intermediär (harter Herd im weichen SCT oder weichen RAM; Fehlen von weichem SCT oder Muskelgewebe zwischen Herd und Faszie; harte Bereiche auf der Faszie) oder tief (harter Herd mit Lokalisation im RAM; weiches Muskelgewebe zwischen Faszie und Herd; keine harten Bereiche auf der Faszie). Diese Befunde wurden bei der Operation verifiziert, die Chirurgen wurden verblindet in Bezug auf die Elastografie-Er-
● ultrasound ● endometriosis ● elastography " "
received accepted
27.1.2014 4.12.2014
Bibliography DOI http://dx.doi.org/ 10.1055/s-0034-1398834 Published online: 2015 Ultraschall in Med © Georg Thieme Verlag KG Stuttgart · New York · ISSN 0172-4614 Correspondence Dr. Slawomir Wozniak 3rd Chair and Deartment of Gynecology, Medical University of Lublin Jaczewskiego 8 20–954 Lublin Poland Tel.: ++ 48/5 02 07 38 33 Fax: ++ 48/81/7 24 48 48 [email protected]
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Die Elastografie verbessert die Genauigkeit des Ultraschalls bei der präoperativen Beurteilung der Endometriose der Bauchwand
correct in 33.3 % of cases, while adding the elastography option improved the accuracy of AWE location assessment to 87.9 % (p < 0.05). The diagnostic accuracy of ultrasound alone, but not with the elastography option, was significantly decreased in the preoperative assessment of AWE location in overweight and obese patients. 4 patients required implantation of a mesh. In all cases the pathological examination confirmed the diagnosis of AWE. Conclusion: Elastography significantly improved the accuracy of ultrasound in evaluating the depth of infiltration of AWE, is not affected by increased BMI, and should be considered in patients qualified for surgical treatment of AWE.
gebnisse. Auch der Einfluss von Adipositas auf die Genauigkeit des Ultraschalls und der Elastografie bei der Beurteilung der Lokalisation der AWE wurde untersucht. Ergebnisse: Bei der Operation wurde die AWE bei 6 als oberflächlich, bei 19 als intermediär und bei 8 Patienten als tief diagnostiziert. Die präoperative Ultraschallbeurteilung war in 33,3 % der Fälle richtig, wobei die Elastografie-Option die Genauigkeit der Lokalisation der AWE auf 87,9 % (p < 0.05). Die diagnostische Genauigkeit des Ultraschalls alleine, ohne Elastografie-Option führte zu einem statistisch signifikanten Rückgang der Genauigkeit der Lokalisation der AWE bei übergewichtigen und adipösen Patienten. Bei 4 Patienten war die Implantation eines Netzes erforderlich. In allen Fällen wurde die AWE-Diagnose durch die pathologische Untersuchung bestätigt. Schlussfolgerung: Die Elastografie verbesserte die Genauigkeit der Sonografie signifikant in Bezug auf die Beurteilung der Infiltrationstiefe der AWE. Sie wird nicht von einem erhöhten BMI beeinflusst und kann bei Patienten, die für eine chirurgische Behandlung der AWE vorgesehen sind, zum Einsatz kommen.
Endometriosis is defined as the presence of endometrial glands and stroma outside the uterine cavity [1]. Typically, endometrial implants are located in the minor pelvis (ovaries, pelvic peritoneum, rectovaginal septum, etc.), but can also be found in other locations such as the brain, lungs and abdominal wall (subcutaneous tissue and abdominal wall muscles). Abdominal wall endometriosis (AWE) usually develops in the region of a previous cesarean section scar, but has also been described after hysterectomies and laparoscopies or even without previous surgery [2, 3]. The risk of AWE after a cesarean section is estimated at 0.03 – 1 % [4]. Typical symptoms of AWE include a palpable mass near a surgical scar and cyclic pain associated with menses. In most cases a thorough history and physical examination are sufficient to make a correct diagnosis [5]. The treatment of choice of AWE is surgical excision, and the diagnosis is confirmed by a pathological examination. AWE is frequently located in the subcutaneous tissue, but can also infiltrate the abdominal rectus muscle and/or its fascia, making the surgery more difficult and sometimes requiring implantation of a mesh [6]. Therefore, precise preoperative assessment is important when planning surgical treatment of AWE. Considering the fact that during ultrasound examination AWE lesions appear to have ill-defined, blurred, often spiculated margins [6, 7], it may be difficult to evaluate AWE infiltration by conventional B-mode ultrasound alone. There are no reports evaluating the usefulness of other imaging techniques (CEUS, MRI) in the preoperative assessment of AWE location. Elastography is a novel ultrasound-based imaging modality that assesses the elasticity of visualized tissues [8, 9]. One of the many elastography methods is strain elastography, based on the phenomenon that after applying pressure with the probe the strain of hard tissues is lower than that of soft tissues. Gradient values of strain are visualized on a color map, representing the stiffness of the examined area. The use of elastography in the imaging of hard masses in softer tissues for describing their location and size and selecting biopsy regions has been described in breast, prostate, thyroid and other tumors [10 – 15]. The application of elastography in obstetrics and gynecology has also been reported, for instance in predicting the success of the induction of labor [16, 17] and for the differential diagnosis of endometrial pathologies [18].
The objective of this prospective observational study was to assess the potential role of elastography in the preoperative ultrasound assessment of AWE location.
Wozniak S et al. Elastography Improves the … Ultraschall in Med
Materials and Methods !
Patients with suspected AWE (based on medical history, signs and symptoms: palpable mass in the region of C-section scar; cyclic or continuous pain) in the previous C-section scar were qualified for initial B-mode ultrasound scan. Only patients with AWE visible on B-mode ultrasound were asked to participate in the study and qualified for surgical excision of AWE. Data on patient’s age, BMI and obstetrical history was collected. During preoperative assessment each patient underwent a two-stage ultrasound evaluation of AWE size (maximal diameter) and location: first only by B-mode ultrasound and then in the alpha-blend elastography (combined Bmode and elastography color map). During surgery the location of " Fig. 1). AWE was verified and the lesions were measured again (● All lesions were sent for histopathological examination to confirm the diagnosis. All patients presented for a control examination in our department one month after surgery to receive their histopathological results and to assess the postoperative course. All ultrasound examinations were performed transabdominally by one experienced sonographer (SW; 20 years of experience in obstetrics and gynecology ultrasound, 5 years of elastography experience) on a Samsung Medison V20 Prestige equipped with a transvaginal (4 – 9 MHz) convex probe and Elastoscan® option. Considering the greater availability of the transvaginal probe in gynecological departments, we have decided to use only the transvaginal probe instead of the linear transabdominal probe. In all cases the following B-mode settings were used: focus set on the lower end of the lesion, gain adjusted to obtain best image quality, tissue harmonic imaging activated. Additionally, the vascularization (number of blood vessels) of AWE lesions was assessed using the power Doppler option with a pulse repetition frequency of 600 Hz. After visualizing the AWE lesion in B-mode ultrasound, the probe was positioned centrally over the lesion and the Elastoscan option was activated. The probe was held still without any additional pressure for about 15 seconds. The elastographic image was generated by the patient’s breathing movements and arterial
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Original Article
pulsation. The elasticity of tissues was visualized using a color map from red (soft) to purple (hard). Alpha-blend elastography was used where the B-mode image was blended with the elastographic color map, which depicted both the hyperechogenic fascia and the " Fig. 2). After freezing the image, the hard (purple) AWE nodule (●
Fig. 1 Flowchart of the study design Abb. 1 Flussdiagramm des Studiendesigns.
stored cine loop was reviewed slowly to select the most reproducible frame. The location of AWE was described similarly to Savelli et al. as superficial (S; in subcutaneous tissue only, above fascia), intermediate (I; infiltrating the abdominal rectus muscle fascia) and deep (D; in the abdominal rectus muscle, below fascia) [6] " Fig. 3). The criteria for B-mode ultrasound assessment of AWE (● location were: superficial (located in the subcutaneous tissue only; subcutaneous tissue visible between the fascia and the lesion; intact fascia), intermediate (located in the subcutaneous tissue or in the rectus abdominis muscle; no subcutaneous or muscle tissue between the lesion and the fascia; fascia infiltrated); or deep (located in the rectus abdominis muscle; muscle tissue visible between the lesion and the fascia; fascia intact). The criteria for the alpha-blend elastography assessment of AWE location were: superficial (hard lesion located in soft subcutaneous tissue; soft subcutaneous tissue between the fascia and the lesion; no hard areas on the fascia); intermediate (hard lesion in the soft subcutaneous tissue or soft rectus abdominis muscle; no soft subcutaneous or muscle tissue between the lesion and the fascia; hard areas on the fascia); or deep (hard lesion located in the soft rectus abdominis muscle; soft muscle tissue between the fascia and the lesion; no hard areas on the fascia). All surgical interventions and intraoperative assessment of AWE size and location were performed by PC, PM and PS, who were blinded to the results of imaging examinations. The measurements were performed using a sterile ruler after dissecting the lesion and finding the largest macroscopic diameter (including the spiculated margins). To evaluate the possible influence of obesity on the accuracy of ultrasound and elastography in assessing the location of AWE, patients were stratified on the basis of BMI to overweight/obese (BMI > 25) and with normal BMI (BMI ≤ 25). The study protocol was accepted by a local Bioethics committee. All patients signed an informed consent to participate in the study. Statistical analysis was performed using Statistica software (version 10, Statsoft, USA). Maximal AWE diameters assessed by all methods were first compared by Friedman ANOVA and then by
Fig. 2 A B-mode ultrasound image of AWE. The lesion appears to have regular margins, and the fascia (arrow) appears intact. B Elastographic image of the same AWE lesion. The lesion seems larger, its margins appear irregular, spiculated and infiltrating the fascia (arrow). C Resected surgical specimen shows irregular, spiculated margins (arrows). D A fascial defect after resection of AWE is shown (arrow). Sometimes a non-resorbable mesh may be required to fix the defect. Abb. 2 A B-Mode-US einer AWE. Der Herd scheint gleichmäßige Ränder zu haben, die Faszie (Pfeil) erscheint intakt. B Elastografisches Bild desselben AWE-Herdes. Der Herd erscheint größer, dessen Ränder erscheinen irregulär, nadelartig und infiltrieren die Faszie (Pfeil). C Die entnommene chirurgische Probe zeigt irreguläre, nadelartige Ränder (Pfeile). D Eine Schädigung der Faszie nach Resektion der AWE wird gezeigt (Pfeil). Manchmal kann ein nicht-resorbierbares Netz nötig sein, um den Schaden zu beheben.
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Original Article
Original Article
Characteristics of the studied population.
age (years; median, range)
30
20 – 42
time from C/S (months; median, range)
23
14 – 50
BMI (median, range) no. of previous C/S (n, %)
symptoms suggestive of deep endometriosis (n, %)
Fig. 3 The location of AWE: superficial (S; in subcutaneous tissue only, above fascia), intermediate (I; infiltrating the abdominal rectus muscle fascia) and deep (D; in the abdominal rectus muscle, below fascia). Abb. 3 Die Lokalisierung der AWE: Oberflächlich (S; nur im subkutanen Gewebe, oberhalb der Faszie), intermediär (I; Infiltration der Faszie des M. rectus abdominis) und tief (D; im M. rectus abdominis, unterhalb der Faszie).
Wilcoxon signed rank test. The accuracy of B-mode ultrasound and alpha-blend elastography AWE location assessment was compared using the McNemar’s test. The accuracy of B-mode ultrasound and alpha-blend elastography in patients with normal and abnormal BMI was compared using the χ2 test. P-values < 0.05 were considered significant.
Results
22,9
17.9 – 34.1
1
22
66.7 %
2
10
30.3 %
3
1
3%
dysmenorrhea
20
60.6 %
dyspareunia
12
36.4 %
" Fig. 4). The values obtained during alpha-blend elasp < 0.001) (● tography and surgical assessment were not significantly different " Fig. 4). (p = 0.54) (● Influence of BMI on the performance of B-mode ultrasound and alpha-blend elastography in the preoperative assessment of AWE " Table 3, 4. The accuracy of B-mode ultrasound in evalis shown● uating AWE location was significantly worse in overweight and obese patients in comparison to patients with normal BMI (7.7 % " Table 3). The accuracy of alpha-blend elasvs 50 %; p = 0.012) (● tography in evaluating AWE location did not differ between normal BMI and overweight/obese patients (90 % vs. 84.6 %; p = 0.64) " Table 4). (● In 21 (63.6 %) AWE lesions, no blood flow was observed, 1 blood vessel was visible in 5 (15.2 %) cases, 2 blood vessels in 4 (12.1 %) cases and 3 or more blood vessels in 3 (9.1 %) cases. In 4 patients (12.1 %) the fascial defect required implanting a mesh. No complications occurred during the surgeries. In all cases the postoperative course was not complicated. During the data collection period, none of the patients had recurrence of AWE symptoms (follow-up 6 – 24 months). In all cases the pathological examination confirmed the diagnosis and complete removal of AWE.
!
The initial B-mode ultrasound scan was performed in 36 patients with suspected AWE. In 33 patients AWE was visualized and " Fig. 2). these patients were included in the study (● The clinical characteristics of the studied 33 patients are shown in ●" Table 1. A detailed description of the patients’ BMI, AWE symptoms and results of B-mode ultrasound, alpha-blend elastogra" Taphy, and surgical evaluation of AWE lesions is presented in ● ble 2. In the studied group 39.4 % of patients were overweight/ obese, a palpable mass was present in 87.9 % cases, 66.7 % of patients reported cyclic pain, 21.2 % reported continuous pain and 12.1 % had no pain at all. During surgery the location of AWE was assessed as superficial in 6 patients (18.2 %), intermediate (infiltrating fascia) in 19 patients " Table 2). Preoperative (57.6 %) and deep in 8 patients (24.2 %) (● B-mode ultrasound assessment was correct (concordant with surgical evaluation) in 33.3 % of cases, while alpha-blend elastography allowed a more accurate evaluation of AWE location " Table 2). The McNemar’s test showed (87.9 % of correct cases) (● that the accuracy of alpha-blend elastography in assessing AWE location was significantly better in comparison to B-mode ultrasound (p < 0.001). Friedman ANOVA showed a significant difference between Bmode ultrasound, alpha-blend elastography and surgical measurements (p < 0.001). Median maximum diameter of the AWE lesions estimated by B-mode ultrasound was 27 mm (range 5 – 36 mm) and was significantly lower than the median maximum diameters assessed by alpha-blend elastography (30 mm; range 8 – 42; p < 0.001) and during surgery (30 mm; range 8 – 41; Wozniak S et al. Elastography Improves the … Ultraschall in Med
Discussion !
The median maximum AWE diameter observed in our study is consistent with the literature. Horton et al. in a review of 445 cases of AWE calculated the mean largest dimension to be 27 mm (95 % CI, 21 – 32 mm), with no statistical differences between included studies [3]. Interestingly, in our study the diameters obtained by B-mode ultrasound were significantly lower than those obtained by alpha-blend elastography or during surgery. It may point to the fact that alpha-blend elastography improves the accuracy of Bmode ultrasound in measuring AWE, probably due to better visualization of infiltrating margins of AWE lesions. However, it has to be stated that while surgical assessment may be considered a “gold standard” in evaluating AWE location, its accuracy in measuring AWE size may be questionable. The infiltrating, irregular, spiculated margins of AWE lesions are difficult to measure during " Fig. 1). macroscopic assessment (● The majority of examined AWE lesions showed no blood flow or only 1 – 2 vessels. These results are similar to those obtained by Savelli et al. 2012, who found ≤ 3 blood vessels in all 21 AWE lesions examined [6]. Therefore, it is unlikely that the classic Doppler examination may play a role in preoperative assessment of AWE location. Correct preoperative assessment of AWE location undoubtedly is important. Small AWE lesions located in the subcutaneous tissue only are usually easy to remove. Infiltration of the rectus muscle fascia or the muscle layer itself makes the surgery much more difficult, and may require a wider laparotomy
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Table 1
Original Article
BMI
symptoms of AWE palpable
pain
mass
preoperative AWE location assessment B-mode ultra-
alpha blend elasto-
sound
graphy
AWE location – surgical findings
1
N
YES
CYC
C
C
S
2
O
YES
CON
IC
C
I
3
N
YES
NO
IC
C
D
4
O
NO
CYC
IC
C
D
5
N
YES
CYC
C
C
I
6
N
YES
CON
C
C
S
7
N
YES
CON
IC
C
I
8
N
YES
CYC
C
C
D
9
N
YES
CYC
IC
IC
I
10
N
YES
CYC
C
C
D
11
N
YES
NO
IC
C
I
12
O
NO
CYC
IC
C
I
13
N
YES
CON
IC
IC
I
14
O
YES
CYC
IC
C
I
15
O
YES
NO
IC
C
I
16
O
NO
CYC
IC
C
I
17
O
YES
CYC
IC
C
I
18
N
YES
CYC
C
C
S
19
O
YES
CYC
IC
IC
I
20
N
YES
NO
C
C
S
21
O
YES
CON
IC
C
I
22
N
YES
CYC
IC
C
D
23
N
YES
CYC
IC
C
I
24
N
YES
CON
C
C
I
25
O
YES
CYC
IC
C
I
26
O
YES
CYC
IC
C
I
27
N
YES
CYC
C
C
S
28
N
YES
CYC
C
C
I
29
O
YES
CYC
C
C
S
30
O
NO
CON
IC
IC
D
31
N
YES
CYC
IC
C
D
32
N
YES
CYC
IC
C
I
33
N
YES
CYC
IC
C
D
Table 2 Relationship of BMI, signs, symptoms, B-mode ultrasound and alpha-blend elastography findings and surgical diagnosis.
AWE – abdominal wall endometriosis; N – normal BMI; O – overweight/obese; CYC – cyclic pain; CON – continuous pain; C – correct; IC – incorrect; S – superficial; I – intermediate; D – deep
Fig. 4 Maximum diameters of AWE lesions assessed by B-mode ultrasound, alpha-blend elastography and during surgery. AWE – abdominal wall endometriosis; * p < 0.05; NS – not significant Abb. 4 Maximale Durchmesser der AWE-Herde, bestimmt durch B-Bild Sonografie, Alpha-BlendElastografie und bei der Operation. AWE – abdominale Endometriose der Bauchwand; * p < 0,05; NS – nicht signifikant
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patient
Table 3 Accuracy of the B-mode ultrasound assessment of AWE location in overweight/obese and normal BMI patients.
incorrect B-mode
correct B-mode
statistical
ultrasound
ultrasound
analysis
assessment
assessment
normal BMI
10 (50 %)
10 (50 %)
overweight/ obese
12 (92 %)
1 (8 %)
χ2 = 6.35 p = 0.012
Table 4 Accuracy of the alpha-blend elastography assessment of AWE location in overweight/obese and normal BMI patients.
incorrect alpha-
correct alpha-
statistical
blend elastography
blend elasto-
analysis
assessment (n)
graphy assessment (n)
normal BMI
2 (10 %)
18 (90 %)
overweight/ obese
2 (15 %)
11 (85 %)
χ2 = 0.21 p = 0.64
and sometimes implantation of a mesh. Therefore, knowledge of AWE location may be helpful in planning the surgery, choosing the reference hospital and surgical team, predicting the time of surgery and securing additional material, such as a mesh. For example, in the study by Francica et al., repair of the fascia and/or abdominal rectus muscle was necessary in 5 out of 12 patients (41.6 %) [5], while in our group in 81.8 % of patients at least a minor infiltration of the fascia and/or muscle was present. Bektas et al. implanted a mesh in 4 out of 40 patients (10 %) operated on because of AWE [19]. Similarly, in our study 12.1 % of patients required implantation of a mesh. That is why it is important to differentiate various locations of AWE during preoperative assessment. In a recent report AWE location was described as superficial in 57 % of patients, intermediate in 24 % and deep in 19 % [6]. However, these findings were based only on ultrasound and were not verified by surgery. Interestingly, the results of the B-mode ultrasound assessment of AWE location in our study were similar, with the majority of lesions described as superficial (45.5 %) and a smaller percentage as intermediate (18.2 %) and deep (33.3 %). Out of 16 cases in which AWE was described as superficial on the basis of B-mode ultrasound, only 6 were confirmed during surgery, while in 10 cases infiltration of the rectus muscle sheath was observed. After surgical assessment only 18.2 % cases were found to be superficial, 63.5 % were intermediate and 24.3 % were deep. These results suggest that infiltration of the fascia may be much more common than expected after B-mode ultrasound examination. Our results clearly show that preoperative B-mode ultrasound assessment of AWE location is not reliable with an overall accuracy of 33.3 %, which was significantly worse than the accuracy of alpha-blend elastography (87.9 %). All cases of incorrect B-mode ultrasound evaluation occurred in intermediate and deep AWE lesions. As expected, B-mode ultrasound examination of superficial lesions was easier and was correct in all 5 cases of superficial AWE. When using the alpha-blend elastography mode, the fascia appears as a hyperechogenic line. AWE lesions appear as hard (purple) nodules and can be distinguished from softer surrounding tissues, their correspondence to the fascia is also visualized
Wozniak S et al. Elastography Improves the … Ultraschall in Med
" Fig. 1), which may explain the overall performance of alpha(● blend elastography. The major disadvantage of alpha-blend elastography is that due to the presence of many techniques and processing algorithms for producing and displaying elastographic images, the findings may be specific to a particular system [20]. In our study, the software (Elastoscan) did not require the use of compression/decompression cycles, which may decrease the interobserver variability [17]. In our study the accuracy of B-mode ultrasound in assessing AWE location was surprisingly low. Unfortunately, we did not identify any studies comparing the ultrasound assessment of AWE location with surgical findings. However, some authors evaluated the accuracy of ultrasound in differential diagnosis of AWE lesions and acquired disappointing results. In the study by Bektas et al., preoperative ultrasound diagnosis was correct in 47.5 % of cases [19], while in the study by Ozel et al. ultrasound provided conclusive information only in 11.1 % patients [21]. It seemed reasonable to assume that preoperative B-mode ultrasound assessment of AWE lesions may be impaired in overweight and obese patients due to increased thickness of the subcutaneous tissue. To the best of our knowledge, this is the first report addressing this issue. In our group 13 patients were overweight or obese and B-mode ultrasound AWE location assessment was correct in only 1 case (7.7 %). During surgery in overweight/obese patients, the majority of AWE lesions were found to be intermediate or deep (12 cases), while only one was superficial. Interestingly, B-mode ultrasound assessment was correct only in the case of superficial AWE, which shows that B-mode ultrasound evaluation of deeper layers in overweight/obese patients is, as expected, not satisfactory. Moreover, B-mode ultrasound AWE location assessment was significantly better in patients with a nor" Table 3), which mal BMI than in overweight/obese patients (● confirms the hypothesis that increased BMI impairs the performance of B-mode ultrasound in evaluating AWE. On the other hand, since elastography is an imaging modality designed specifically to differentiate soft and hard tissues, it seemed a perfect technique to distinguish soft subcutaneous tissue from hard AWE lesions in overweight/obese patients. We did indeed observe that increased BMI did not affect the performance of al" Tapha-blend elastography in assessing the location of AWE (● ble 4). Therefore, we can state that the accuracy of B-mode ultrasound in assessing AWE location is greatly diminished by increasing BMI, while alpha-blend elastography remains independent of this factor. Even though the use of magnetic resonance imaging (MRI) and computed tomography (CT) in diagnosing AWE has been described by some authors [22, 23], these techniques do not seem to provide additional information to a properly performed ultrasound examination and are unlikely to modify the treatment strategy [7]. In a recent study Ozel et al., reported that CT did not provide conclusive information in any of the 4 cases in which it was performed, while MRI provided conclusive information in only 4 of 8 cases [21]. However, it has to be stressed that MRI and CT were used in these studies for the differential diagnosis of abdominal masses and not for the assessment of AWE location. Moreover, many groups state that the typical history, symptoms and physical examination are sufficient to make a diagnosis of AWE [5, 24] and this approach is used in our department as well. Therefore, performing additional diagnostic procedures, such as MRI and CT, does not seem necessary and may only impair the overall cost-effectiveness. Preoperative alpha-blend elas-
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tography examination may provide reliable assessment of AWE lesion location, which is important in planning surgical treatment.
Conclusion !
1. Alpha-blend elastography improves the performance of Bmode ultrasound in the preoperative assessment of AWE location. 2. The accuracy of alpha-blend elastography in the preoperative assessment of AWE location is not decreased in overweight and obese patients. 3. Alpha-blend elastography provides important information in the preoperative assessment of patients qualified for surgical treatment of AWE.
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