Original Article
Diagnostic performance of indirect MR arthrography for the diagnosis of rotator cuff tears at 3.0 T
Acta Radiologica 2015, Vol. 56(6) 720–726 ! The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0284185114537817 acr.sagepub.com
Ji Hyun Lee, Young Cheol Yoon and Sukkyung Jee
Abstract Background: Indirect magnetic resonance (MR) arthrography is a non-invasive method for shoulder imaging. However, there are no studies that have examined the diagnostic performance of indirect MR arthrography for the diagnosis of rotator cuff tears in a large patient population. Purpose: To assess the diagnostic performance of indirect fast spin-echo (FSE) MR arthrography for the diagnosis of rotator cuff tears at 3.0 T. Material and Methods: A total of 149 patients who had undergone indirect shoulder MR arthrography followed by arthroscopic surgery were enrolled in this retrospective study. Two musculoskeletal radiologists evaluated images from each patient for the presence of supraspinatus-infraspinatus (SSP-ISP) or subscapularis (SSC) tendon tears. Using the arthroscopic findings as the reference standard, the overall diagnostic performance and detection rates for SSP-ISP and SSC tendon tears were calculated. Results: The sensitivity, specificity, and accuracy of readers I and II for the diagnosis of SSP-ISP tendon tears were 94% and 95%, 89% and 85%, and 93% and 93%, respectively. The sensitivity of imaging for detection of SSP-ISP tendon tears by readers I and II were 100% and 100% for full-thickness tears and 84% and 86% for partial-thickness tears, respectively. The sensitivity, specificity, and accuracy of readers I and II for the diagnosis of SSC tendon tears were 80% and 76%, 89% and 93%, and 85% and 85%, respectively. Conclusion: Indirect MR arthrography is useful for the detection of SSP-ISP and SSC tendon tears.
Keywords Magnetic resonance imaging (MRI), 3.0 T, indirect arthrography, shoulder, rotator cuff Date received: 21 January 2014; accepted: 8 May 2014
Introduction Direct magnetic resonance (MR) arthrography has been widely used for the diagnosis of glenoid, labrum, and rotator cuff lesions (1–5). However, this procedure is invasive and usually requires imaging guidance (6–8). The use of paramagnetic contrast media in indirect MR arthrography, on the other hand, provides arthrogramlike images by enhancing the highly vascular synovial membrane within the joint cavity without radiation exposure, invasive procedures, or coordination of additional scheduling (9–13). Due to these advantages, this technique was proposed as an alternative to direct MR arthrography (14). Several studies have reported improved diagnostic performance of indirect MR arthrography compared with conventional non-
contrast MR imaging (10,13). In addition, a recent study based on a relatively small number of patients showed no significant difference in the diagnostic accuracy of indirect and direct MR arthrography regarding rotator cuff, labral, and long head of the biceps tendon tears (15). However, to our knowledge, there are no studies that have examined the diagnostic performance Department of Radiology, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, Republic of Korea Corresponding author: Young Cheol Yoon, Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50, Ilwon-Dong, KangnamKu, Seoul, 135-710, Republic of Korea. Email: [email protected]
Lee et al. of indirect MR arthrography for rotator cuff tears in a large patient population. The purpose of this study was to assess the diagnostic performance of indirect fast spin-echo (FSE) MR arthrography for the diagnosis of rotator cuff tears at 3.0 T.
Material and Methods Patients Our institutional review board approved this retrospective study protocol. From March 2011 to March 2012, 149 patients who had undergone indirect shoulder MR arthrography followed by arthroscopic surgery within 1 week were enrolled in this study. Two patients had bilateral rotator cuff tears, one of whom underwent arthroscopic surgery for each shoulder with a 5-month interval between the two operations. In the case of the second patient, only one shoulder was included in this study because indirect MR arthrography was not performed for the other shoulder. As a result, our study includes data from a total of 150 shoulders in 149 patients (age range, 17–78 years; mean age, 55.9 years). None of the patients had undergone previous surgery on the symptomatic shoulder. The study population consisted of 64 men (age range, 17–75 years; mean age, 48.5 years) and 86 women (age range, 35–78 years; mean age, 61.4 years). The most common symptoms were pain with or without limitation of movement, shoulder dislocation, or weakness.
MR imaging protocol Based on the clinical standard protocol for indirect MR arthrography, 0.1 mmol/kg of gadopentetate dimeglumine (Gd-DTPA, Magnevist, Bayer Schering Pharma AG, Berlin, Germany) was injected into the antecubital vein. Immediately after the injection of contrast media, patients were instructed to exercise their shoulders for 15 min. MR imaging (MRI) was then performed with a 3.0 T scanner (Gyroscan Intera Achieva, Philips Medical Systems, Best, The Netherlands) with a dedicated receive-only shoulder coil. Patients were positioned with the humerus in a neutral position and the thumb pointing upward. Several MR sequences were performed including fatsuppressed T1-weighted (T1W) FSE sequences in the axial plain (TR/TE, 340–610/8–10 ms; section thickness, 3 mm; field of view [FOV], 16 cm; matrix size, 320 256; echo train length, 5; number of averages, 2), the coronal oblique plane parallel to the long axis of the supraspinatus tendon (TR/TE, 560–754/8–10 ms; section thickness, 3 mm; FOV, 16 cm; matrix size, 320 256; echo train length, 5; number of averages,
721 2), and in the sagittal oblique plane perpendicular to the long axis of the supraspinatus tendon (TR/TE, 560– 754/8–10 ms; section thickness, 3 mm; FOV, 16 cm; matrix size, 320 256; echo train length, 5; number of averages, 2). T2-weighted (T2W) FSE sequences were obtained in the axial plane (TR/TE, 3272–3544/80 ms; section thickness, 3 mm; FOV, 16 cm; matrix size, 320 256; echo train length, 16; number of averages, 2), the coronal oblique plane (TR/TE, 3272–4090/57– 80 ms; section thickness, 3 mm; FOV, 16 cm; matrix size 320 256; echo train length, 16; number of averages, 2), and in the sagittal oblique plane (TR/TE, 3272– 4747/54–80 ms; section thickness, 3 mm; FOV, 16 cm; matrix size, 320 256; echo train length, 16; number of averages, 2). The total imaging time was 23 min and 46 s.
Analysis of MR images T1W and T2W imaging sequences were retrospectively and independently reviewed by two musculoskeletal radiologists with 8 and 2 years of experience in musculoskeletal radiology who were blinded to the arthroscopic results. Using a three-point grading scale, the radiologists scored each SSP-ISP tendon lesion as grade 2, 1, or 0 for a full-thickness tear, partial-thickness tear, or no tear, respectively. Intrasubstance tears were disregarded, as they could not be confirmed on arthroscopic findings. The readers also recorded whether an SSC tendon tear was present. Images were presented in random order at each reading session and evaluated using a picture archiving and communication system (PACS) (Centricity Radiology RA 1000; GE Healthcare, Chicago, IL, USA). The criterion used for the diagnosis of a fullthickness tear was high signal intensity on both T1W and T2W images involving the entire thickness extending from the articular surface of the rotator cuff to the subacromial/subdeltoid bursa, as well as tendinous discontinuity with or without retraction of the musculotendinous junction (16). The criterion used for the diagnosis of a partial-thickness tear was high signal intensity on both T1W and T2W images extending across a portion of the tendon involving either the bursal or the articular surface with surface abnormalities, though not through the entire thickness of the tendon (16). If intratendinous high signal intensity not extending to the articular or bursal surface was noted, which is suspicious for intrasubstance tear, it was not scored as a tear. The criterion used for the diagnosis of a subscapularis tendon tear was high signal traversing the tendon gap, retraction of the tendon away from its normal attachment site on the lesser tuberosity, or malposition of the long head of the biceps tendon (16).
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Arthroscopic surgery The arthroscopic findings for each patient were used as the reference standard. Surgery were performed by an orthopedic surgeon with eight years of experience performing shoulder surgery, not blinded to the MR arthrographic findings. The surgeon recorded the presence of SSP-ISP and/or SSC tendon tears. The tears were categorized as full-thickness or partial-thickness for SSP-ISP tendon tears or as complete or partial for SSC tendon tears.
Statistical analysis The sensitivity, specificity, and accuracy for both readers were calculated for the detection of overall SSPISP tendon tears (full- and partial-thickness tears together without considering the grades of the tears). The sensitivity for the detection of full- and partialthickness tears was assessed separately. The sensitivity, specificity, and accuracy were also evaluated for the detection of SSC tendon tears. Intraclass correlation coefficient (ICC) scores with a confidence interval of 95% were used to evaluate the agreement of scores for SSP-ISP tendon tears between MR images and arthroscopic findings for each reader. Inter-observer agreement for detecting rotator cuff tears between the two readers was categorized using kappa statistics, whereas that for grading SSP-ISP tendon tears was also calculated using ICC values. Inter-observer agreement using kappa statistics was rated as ‘‘poor’’ for a k value of less than 0, ‘‘slight’’ for a k value of 0– 0.20, ‘‘fair’’ for a k value of 0.21–0.40, ‘‘moderate’’ for a k value of 0.41–0.60, ‘‘substantial’’ for a k value of 0.61–0.80, and ‘‘excellent’’ for a k value of 0.81–1.0. An ICC value greater than 0.75, was considered to represent good agreement. All statistical analyses were performed using statistical softwares (SPSS Statistics Standard, version 18.0.0, IBM,
Chicago, IL, USA; MedCalc 12.5.0.0, Mariakierke, Belgium).
Software,
version
Results A total of 123 SSP-ISP tendon tears (80 full-thickness tears, 43 partial-thickness tears) and 75 SSC tendon tears (1 complete tear, 74 partial-tears) were identified during arthroscopic surgery. Among the 43 partialthickness tears, the numbers of articular- and bursalsided tears were 11 and 32, respectively. The number of intrasubstance tears detected at MR by both readers was 10, but they could not be confirmed by arthroscopy. Rotator cuff tears were not observed in 24 patients, nine of whom were identified as having shoulder dislocation, four as having paralabral cysts, four as having labral tears, four as having adhesive capsulitis, two as having calcific tendinitis, and one as having a biceps pulley lesion. The overall diagnostic performance for SSP-ISP and SSC tendon tears in both readers were summarized in Table 1. The sensitivity, specificity, and accuracy for the diagnosis of overall SSP-ISP tendon tears were 94%, 89%, and 93% for reader I, and 95%, 85%, and 93% for reader II, respectively. All full-thickness tears of SSP-ISP tendons were detected by both readers on imaging (Fig. 1). The sensitivity for detection of partial-thickness tears was 84% and 86% for readers I and II, respectively (Figs. 2 and 3). The sensitivity, specificity, and accuracy for the diagnosis of SSC tendon tears were 80%, 89%, and 85% for reader I, and 76%, 93%, and 85% for reader II, respectively (Fig. 4). Interpretations of indirect MR arthrography for both readers were compared with arthroscopic findings and summarized in Table 2. The ICC values and 95% confidence intervals for the grading of SSP-ISP tendon tears for readers I and II were 0.934 (95% CI, 0.908–0.952) and 0.906 (95% CI,
Table 1. Diagnostic performance in the evaluation of SSP-ISP and SSC tendon tears. Reader I
SSP-ISP Any tear* FTT PTTy SSCz
Reader II
Sensitivity
Specificity
Accuracy
Sensitivity
Specificity
Accuracy
94 100 84 80
89 (24/27) – – 89 (67/75)
93 (140/150) – – 85 (127/150)
95 100 86 76
85 (23/27) – – 93 (70/75)
93 (140/150) – – 85 (127/150)
(116/123) (80/80) (36/43) (60/75)
(117/123) (80/80) (37/43) (57/75)
*Data include all kinds of SSP-ISP tendon tears, including full- and partial-thickness tears. y Data include partial-thickness tears of the SSP-ISP tendon, including articular-and bursal-sided tears. z Data include all kinds of SSC tendon tears, including full- and partial-thickness tears. FTT, full-thickness tear; PTT, partial-thickness tear.
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Fig. 1. A full-thickness tear involving the supraspinatus-infraspinatus tendon in a 62-year-old woman which was correctly diagnosed by both readers. Fat-suppressed T1W oblique coronal image (a) reveals a tendinous discontinuity with retraction of the musculotendinous junction (arrow). Arthroscopy showed a medium-sized full-thickness tear of the supraspinatus and infraspinatus tendon (b).
Fig. 2. An articular-sided partial-thickness tear involving the supraspinatus tendon in a 57-year-old woman. Fat-suppressed T1W oblique coronal (a) and oblique sagittal (b) images show focal accumulation of contrast material at the articular side of the supraspinatus tendon (arrows). Both readers interpreted the lesion as a partial-thickness tear in the supraspinatus tendon. Arthroscopy confirmed the presence of articular-sided partial-thickness tear of the supraspinatus tendon (not shown).
0.870–0.932), respectively, indicating excellent agreement between MR images and arthroscopic findings for both readers. Inter-observer agreement using k values for the detection of SSP-ISP tendon tears was 0.958 (95% CI, 0.877–1.000), whereas that for detecting SSC tendon tears was 0.783 (95% CI, 0.672–0.880), which were considered to be excellent and substantial, respectively. The ICC value for the grading of SSP-ISP tendon tears was 0.949 (95% CI, 0.929–0.963), which was considered to be excellent.
Discussion Since intra-articular contrast enhancement of the joint after intravenous injection of paramagnetic contrast
media has been reported by several authors (17–20), this non-invasive, ‘‘indirect’’ technique was proposed as an alternative method to direct MR arthrography. Compared with conventional MRI, several studies reported added diagnostic value of indirect MR arthrography. Yagci et al. compared the efficacy of indirect MR arthrography with conventional MRI for the diagnosis of rotator cuff tears, and reported that agreement between indirect MR arthrography and surgery was excellent, whereas that between conventional MRI and surgery was moderate (13). As intravenously injected contrast material diffuses into the joint space, provides reliable outlining of the surface of rotator cuff and leaks into partial tears, indirect MR arthrography detected tears more accurately than conventional MRI. In addition, the use of a fat suppression technique
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Fig. 3. A bursal-sided partial-thickness tear of the supraspinatus tendon in a 52-year-old man. Fat-suppressed T1W oblique coronal image (a) demonstrates discontinuity of the bursal fibers and intact articular fibers at the anterior portion of the supraspinatus tendon (arrow), which was interpreted as a partial-thickness tear by both readers. A thickened joint capsule in axillary recess is also noted, suggesting adhesive capsulitis (arrowhead). Arthroscopy revealed a bursal-sided partial-thickness tear of the supraspinatus tendon (b).
Fig. 4. An articular-sided partial tear at the cranial portion of subscapularis tendon in a 61-year-old woman which was correctly diagnosed by both readers. Fat-suppressed T1W axial (a) and oblique sagittal (b) images show a small hyperintense area at the articular side of the subscapularis tendon (arrows). The patient also had a large-sized full-thickness tear in the supraspinatus-infraspinatus tendon (arrowhead). Arthroscopy confirmed the presence of partial tear of the subscapularis tendon (not shown).
rescaled for smaller variations within the joint result in enhanced image contrast. Also, active exercise of the glenohumeral joint after injection of paramagnetic contrast media effectively increased the rate and degree of enhancement. Dinauer et al. reported higher sensitivity of indirect MR arthrography compared with non-contrast MRI for the diagnosis of superior glenoid labral lesions (10). This method, however, may result in interpretative error due to enhancement of extra-articular structures (9,14). As all vascularized structures and synovial structures such as bursae and tendon sheaths are enhanced regardless if it is normal or abnormal, enhanced rotator cuff due to an inflammation or granulation tissue may cause false-positive interpretations (13). On the other hand, hyperemia related to the
pathologic process will cause intense enhancement, thus help detecting inflamed tissue such as adhesive capsulitis (21). Longer examination times, discomfort when moving the symptomatic shoulder, and the lack of adequate capsular distension are also potential drawbacks of indirect MR arthrography (9,22). In previous studies of SSP-ISP tendon tears, indirect MR arthrography demonstrated high accuracy for the diagnosis of overall tears (sensitivity 67–100%, specificity 75–89%) and full-thickness tears (sensitivity 80– 100%, specificity 88–100%) (13,15,23–25). However, the exact demarcation of degenerative changes and partial-thickness tears are often difficult to identify, making the correct diagnosis difficult regardless of whether non-contrast MRI or MR arthrography is
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Table 2. Comparisons of MR arthrography and arthroscopic findings for both readers. Arthroscopy
Reader I
Reader II
Total
FTT PTT No tear FTT PTT No tear
FTT
PTT
No tear
Total
72 8 0 68 12 0 80
5 31 7 9 28 6 43
0 3 24 0 4 23 27
77 42 31 77 44 29 150
FTT, full-thickness tear; PTT, partial-thickness tear.
utilized (13,26). As a result, the diagnostic accuracy for detection of partial-thickness tears using indirect MR arthrography varied widely in previous reports, with a sensitivity of 38–80% and specificity of 62–88% (23– 25). The sensitivity and specificity in the diagnosis of SSC tendon tears using indirect MR arthrography were reported to be 64% and 75–88% by Jung et al. (15), and 67% and 85% by Oh et al. (25), respectively. We calculated the sensitivity and specificity for overall diagnostic performance including full- and partialthickness tears together for the diagnosis of SSP-ISP tendon tears. The specificity for each type of SSP-ISP tendon tear such as full- or partial-thickness tears were not calculated separately. Instead of specificity, we calculated sensitivity in terms of ‘‘detection rate’’ for each type of SSP-ISP tendon tear. As a result, if an arthroscopically-proven full-thickness tear was interpreted as a partial-thickness tear, it was regarded as a correct detection, and vice versa. As small or partial-thickness tears have increasingly become a source of surgically treatable shoulder pain (27), misinterpretation of tear grading or location may not significantly alter the treatment plan or determination of surgery in the clinical setting. To our knowledge, no data previously existed regarding the detection rate of SSP-ISP tendon tears using indirect MR arthrography. In our study, the diagnostic performance of indirect MR arthrography for overall SSP-ISP tendon tears (either full- or partial-thickness) was comparable to the currently published data, with 94–95% sensitivity and 85–89% specificity. Regarding the grading of SSPISP tendon tears, 90% and 85% of full-thickness tears were correctly graded by readers I and II, whereas 72% and 65% of partial-thickness tears were correctly graded by readers I and II, respectively. Discrepancy between sensitivity in terms of detection rates for partial-thickness tears in SSP-ISP tendons and accuracy for grading partial-thickness tears can be explained by the presence of cases of partial-thickness tears which
were interpreted as full-thickness tears. Among the 43 partial-thickness tears of the SSP-ISP tendon, five (12%) and nine (21%) cases were interpreted as fullthickness tears by readers I and II, respectively. On the other hand, among the 42 and 44 cases which were interpreted as partial-thickness tears by readers I and II, eight (19%) and 12 (27%) cases were proven to be full-thickness tears on arthroscopy, respectively. As a result, the sensitivity and specificity in terms of grading partial-thickness SSP-ISP tendon tears were 72% and 74% for reader I, and 65% and 64% for reader II, respectively, which were comparable to those of previous studies (23–25). The most probable explanation for these misgradings is that high signal intensity after contrast media injection can result from either degenerative changes or partial-thickness tears, making it difficult to correctly interpret the hyperintense area (12,13). However, the sensitivity is increased to 86% in terms of the detection rate, which contradicts previous studies which have regarded the diagnosis of partial-thickness tears using indirect MR arthrography as faulty (24,26). Thus, our results demonstrate the usefulness of indirect MR arthrography for the detection of partial-thickness SSP-ISP tendon tears and for guiding treatment plans. The sensitivity and specificity for detection of SSC tendon tears using indirect MR arthrography were 76–80% and 89–93%, which were higher than those of previous reports (15,25). This study had several limitations. First, we analyzed MR images retrospectively, and the two musculoskeletal radiologists who evaluated the images were aware that the patients had undergone arthroscopic shoulder surgery. This may have introduced a reader bias resulting in the overestimation of rotator cuff tear diagnoses and thus an increase in the sensitivity. Additionally, there may have been a patient selection bias since only patients who had undergone arthroscopic surgery were included in this study. Third, we did not include a control group of patients who underwent conventional MR prior to surgery. In the absence of control group, the value of indirect MR arthrography couldn’t be evaluated in comparison with conventional MR arthrography. Since arthroscopy is an operator-dependent modality, its interpretation is subjective, especially since precise evaluation of the SSC tendon can be difficult and may be missed on both imaging and arthroscopy (28). Notably, all the MR examinations were performed using a 3.0 T scanner only. Although 3.0 T magnets allow high image quality and may improve diagnostic performance, these systems are not widely used in some countries. Finally, assessments for findings with prognostic implications such as size of tear, degree of tendon retraction, and quality of tendon margin were not considered, as well as the side of partial-thickness tears.
726 In conclusion, indirect MR arthrography is a noninvasive, useful method of detecting of SSP-ISP and SSC tendon tears. In contrast to previous reports, indirect MR arthrography also showed excellent sensitivity in terms of detection rates for partial-thickness tears of the SSP-ISP tendon at 3.0 T. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
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Acta Radiologica 56(6) 14. Vahlensieck M, Peterfy CG, Wischer T, et al. Indirect MR arthrography: optimization and clinical applications. Radiology 1996;200:249–254. 15. Jung JY, Yoon YC, Yi SK, et al. Comparison study of indirect MR arthrography and direct MR arthrography of the shoulder. Skeletal Radiol 2009;38:659–667. 16. Opsha O, Malik A, Baltazar R, et al. MRI of the rotator cuff and internal derangement. Eur J Radiol 2008;68: 36–56. 17. Kursunoglu-Brahme S, Riccio T, Weisman MH, et al. Rheumatoid knee: role of gadopentetate-enhanced MR imaging. Radiology 1990;176:831–835. 18. Drape JL, Thelen P, Gay-Depassier P, et al. Intraarticular diffusion of Gd-DOTA after intravenous injection in the knee: MR imaging evaluation. Radiology 1993;188: 227–234. 19. Yamato M, Tamai K, Yamaguchi T, et al. MRI of the knee in rheumatoid arthritis: Gd-DTPA perfusion dynamics. J Comput Assist Tomogr 1993;17:781–785. 20. Winalski C, Weissman B, Aliabadi P, et al. Intravenous Gd-DTPA enhancement of joint fluid: a less invasive alternative for MR arthrography. Radiology 1991;181: 304. 21. Song KD, Kwon JW, Yoon YC, et al. Indirect MR arthrographic findings of adhesive capsulitis. Am J Roentgenol 2011;197:W1105–W1109. 22. Allmann K-H, Scha¨fer O, Hauer M, et al. Indirect MR Arthrography of the Unexercised Glenohumeral Joint in Patients with Rotator Cuff Tears. Invest Radiol 1999;34: 435. 23. Herold T, Bachthaler M, Hamer OW, et al. Indirect MR arthrography of the shoulder: use of abduction and external rotation to detect full- and partial-thickness tears of the supraspinatus tendon. Radiology 2006;240:152–160. 24. Van Dyck P, Gielen JL, Veryser J, et al. Tears of the supraspinatus tendon: assessment with indirect magnetic resonance arthrography in 67 patients with arthroscopic correlation. Acta Radiol 2009;50:1057–1063. 25. Oh DK, Yoon YC, Kwon JW, et al. Comparison of indirect isotropic MR arthrography and conventional MR arthrography of labral lesions and rotator cuff tears: a prospective study. Am J Roentgenol 2009;192:473–479. 26. Rudolph J, Lorenz M, Schroder R, et al. Indirect MR arthrography in the diagnosis of rotator cuff lesions. Rofo 2000;172:686–691. 27. Waldt S, Bruegel M, Mueller D, et al. Rotator cuff tears: assessment with MR arthrography in 275 patients with arthroscopic correlation. Eur Radiol 2007;17:491–498. 28. Pfirrmann CW, Zanetti M, Weishaupt D, et al. Subscapularis tendon tears: detection and grading at MR arthrography. Radiology 1999;213:709–714.
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Diagnostic performance of indirect MR arthrography for the diagnosis of rotator cuff tears at 3.0 T
Acta Radiologica 2015, Vol. 56(6) 720–726 ! The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0284185114537817 acr.sagepub.com
Ji Hyun Lee, Young Cheol Yoon and Sukkyung Jee
Abstract Background: Indirect magnetic resonance (MR) arthrography is a non-invasive method for shoulder imaging. However, there are no studies that have examined the diagnostic performance of indirect MR arthrography for the diagnosis of rotator cuff tears in a large patient population. Purpose: To assess the diagnostic performance of indirect fast spin-echo (FSE) MR arthrography for the diagnosis of rotator cuff tears at 3.0 T. Material and Methods: A total of 149 patients who had undergone indirect shoulder MR arthrography followed by arthroscopic surgery were enrolled in this retrospective study. Two musculoskeletal radiologists evaluated images from each patient for the presence of supraspinatus-infraspinatus (SSP-ISP) or subscapularis (SSC) tendon tears. Using the arthroscopic findings as the reference standard, the overall diagnostic performance and detection rates for SSP-ISP and SSC tendon tears were calculated. Results: The sensitivity, specificity, and accuracy of readers I and II for the diagnosis of SSP-ISP tendon tears were 94% and 95%, 89% and 85%, and 93% and 93%, respectively. The sensitivity of imaging for detection of SSP-ISP tendon tears by readers I and II were 100% and 100% for full-thickness tears and 84% and 86% for partial-thickness tears, respectively. The sensitivity, specificity, and accuracy of readers I and II for the diagnosis of SSC tendon tears were 80% and 76%, 89% and 93%, and 85% and 85%, respectively. Conclusion: Indirect MR arthrography is useful for the detection of SSP-ISP and SSC tendon tears.
Keywords Magnetic resonance imaging (MRI), 3.0 T, indirect arthrography, shoulder, rotator cuff Date received: 21 January 2014; accepted: 8 May 2014
Introduction Direct magnetic resonance (MR) arthrography has been widely used for the diagnosis of glenoid, labrum, and rotator cuff lesions (1–5). However, this procedure is invasive and usually requires imaging guidance (6–8). The use of paramagnetic contrast media in indirect MR arthrography, on the other hand, provides arthrogramlike images by enhancing the highly vascular synovial membrane within the joint cavity without radiation exposure, invasive procedures, or coordination of additional scheduling (9–13). Due to these advantages, this technique was proposed as an alternative to direct MR arthrography (14). Several studies have reported improved diagnostic performance of indirect MR arthrography compared with conventional non-
contrast MR imaging (10,13). In addition, a recent study based on a relatively small number of patients showed no significant difference in the diagnostic accuracy of indirect and direct MR arthrography regarding rotator cuff, labral, and long head of the biceps tendon tears (15). However, to our knowledge, there are no studies that have examined the diagnostic performance Department of Radiology, Samsung Medical Center, Sungkyunkwan University, School of Medicine, Seoul, Republic of Korea Corresponding author: Young Cheol Yoon, Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50, Ilwon-Dong, KangnamKu, Seoul, 135-710, Republic of Korea. Email: [email protected]
Lee et al. of indirect MR arthrography for rotator cuff tears in a large patient population. The purpose of this study was to assess the diagnostic performance of indirect fast spin-echo (FSE) MR arthrography for the diagnosis of rotator cuff tears at 3.0 T.
Material and Methods Patients Our institutional review board approved this retrospective study protocol. From March 2011 to March 2012, 149 patients who had undergone indirect shoulder MR arthrography followed by arthroscopic surgery within 1 week were enrolled in this study. Two patients had bilateral rotator cuff tears, one of whom underwent arthroscopic surgery for each shoulder with a 5-month interval between the two operations. In the case of the second patient, only one shoulder was included in this study because indirect MR arthrography was not performed for the other shoulder. As a result, our study includes data from a total of 150 shoulders in 149 patients (age range, 17–78 years; mean age, 55.9 years). None of the patients had undergone previous surgery on the symptomatic shoulder. The study population consisted of 64 men (age range, 17–75 years; mean age, 48.5 years) and 86 women (age range, 35–78 years; mean age, 61.4 years). The most common symptoms were pain with or without limitation of movement, shoulder dislocation, or weakness.
MR imaging protocol Based on the clinical standard protocol for indirect MR arthrography, 0.1 mmol/kg of gadopentetate dimeglumine (Gd-DTPA, Magnevist, Bayer Schering Pharma AG, Berlin, Germany) was injected into the antecubital vein. Immediately after the injection of contrast media, patients were instructed to exercise their shoulders for 15 min. MR imaging (MRI) was then performed with a 3.0 T scanner (Gyroscan Intera Achieva, Philips Medical Systems, Best, The Netherlands) with a dedicated receive-only shoulder coil. Patients were positioned with the humerus in a neutral position and the thumb pointing upward. Several MR sequences were performed including fatsuppressed T1-weighted (T1W) FSE sequences in the axial plain (TR/TE, 340–610/8–10 ms; section thickness, 3 mm; field of view [FOV], 16 cm; matrix size, 320 256; echo train length, 5; number of averages, 2), the coronal oblique plane parallel to the long axis of the supraspinatus tendon (TR/TE, 560–754/8–10 ms; section thickness, 3 mm; FOV, 16 cm; matrix size, 320 256; echo train length, 5; number of averages,
721 2), and in the sagittal oblique plane perpendicular to the long axis of the supraspinatus tendon (TR/TE, 560– 754/8–10 ms; section thickness, 3 mm; FOV, 16 cm; matrix size, 320 256; echo train length, 5; number of averages, 2). T2-weighted (T2W) FSE sequences were obtained in the axial plane (TR/TE, 3272–3544/80 ms; section thickness, 3 mm; FOV, 16 cm; matrix size, 320 256; echo train length, 16; number of averages, 2), the coronal oblique plane (TR/TE, 3272–4090/57– 80 ms; section thickness, 3 mm; FOV, 16 cm; matrix size 320 256; echo train length, 16; number of averages, 2), and in the sagittal oblique plane (TR/TE, 3272– 4747/54–80 ms; section thickness, 3 mm; FOV, 16 cm; matrix size, 320 256; echo train length, 16; number of averages, 2). The total imaging time was 23 min and 46 s.
Analysis of MR images T1W and T2W imaging sequences were retrospectively and independently reviewed by two musculoskeletal radiologists with 8 and 2 years of experience in musculoskeletal radiology who were blinded to the arthroscopic results. Using a three-point grading scale, the radiologists scored each SSP-ISP tendon lesion as grade 2, 1, or 0 for a full-thickness tear, partial-thickness tear, or no tear, respectively. Intrasubstance tears were disregarded, as they could not be confirmed on arthroscopic findings. The readers also recorded whether an SSC tendon tear was present. Images were presented in random order at each reading session and evaluated using a picture archiving and communication system (PACS) (Centricity Radiology RA 1000; GE Healthcare, Chicago, IL, USA). The criterion used for the diagnosis of a fullthickness tear was high signal intensity on both T1W and T2W images involving the entire thickness extending from the articular surface of the rotator cuff to the subacromial/subdeltoid bursa, as well as tendinous discontinuity with or without retraction of the musculotendinous junction (16). The criterion used for the diagnosis of a partial-thickness tear was high signal intensity on both T1W and T2W images extending across a portion of the tendon involving either the bursal or the articular surface with surface abnormalities, though not through the entire thickness of the tendon (16). If intratendinous high signal intensity not extending to the articular or bursal surface was noted, which is suspicious for intrasubstance tear, it was not scored as a tear. The criterion used for the diagnosis of a subscapularis tendon tear was high signal traversing the tendon gap, retraction of the tendon away from its normal attachment site on the lesser tuberosity, or malposition of the long head of the biceps tendon (16).
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Arthroscopic surgery The arthroscopic findings for each patient were used as the reference standard. Surgery were performed by an orthopedic surgeon with eight years of experience performing shoulder surgery, not blinded to the MR arthrographic findings. The surgeon recorded the presence of SSP-ISP and/or SSC tendon tears. The tears were categorized as full-thickness or partial-thickness for SSP-ISP tendon tears or as complete or partial for SSC tendon tears.
Statistical analysis The sensitivity, specificity, and accuracy for both readers were calculated for the detection of overall SSPISP tendon tears (full- and partial-thickness tears together without considering the grades of the tears). The sensitivity for the detection of full- and partialthickness tears was assessed separately. The sensitivity, specificity, and accuracy were also evaluated for the detection of SSC tendon tears. Intraclass correlation coefficient (ICC) scores with a confidence interval of 95% were used to evaluate the agreement of scores for SSP-ISP tendon tears between MR images and arthroscopic findings for each reader. Inter-observer agreement for detecting rotator cuff tears between the two readers was categorized using kappa statistics, whereas that for grading SSP-ISP tendon tears was also calculated using ICC values. Inter-observer agreement using kappa statistics was rated as ‘‘poor’’ for a k value of less than 0, ‘‘slight’’ for a k value of 0– 0.20, ‘‘fair’’ for a k value of 0.21–0.40, ‘‘moderate’’ for a k value of 0.41–0.60, ‘‘substantial’’ for a k value of 0.61–0.80, and ‘‘excellent’’ for a k value of 0.81–1.0. An ICC value greater than 0.75, was considered to represent good agreement. All statistical analyses were performed using statistical softwares (SPSS Statistics Standard, version 18.0.0, IBM,
Chicago, IL, USA; MedCalc 12.5.0.0, Mariakierke, Belgium).
Software,
version
Results A total of 123 SSP-ISP tendon tears (80 full-thickness tears, 43 partial-thickness tears) and 75 SSC tendon tears (1 complete tear, 74 partial-tears) were identified during arthroscopic surgery. Among the 43 partialthickness tears, the numbers of articular- and bursalsided tears were 11 and 32, respectively. The number of intrasubstance tears detected at MR by both readers was 10, but they could not be confirmed by arthroscopy. Rotator cuff tears were not observed in 24 patients, nine of whom were identified as having shoulder dislocation, four as having paralabral cysts, four as having labral tears, four as having adhesive capsulitis, two as having calcific tendinitis, and one as having a biceps pulley lesion. The overall diagnostic performance for SSP-ISP and SSC tendon tears in both readers were summarized in Table 1. The sensitivity, specificity, and accuracy for the diagnosis of overall SSP-ISP tendon tears were 94%, 89%, and 93% for reader I, and 95%, 85%, and 93% for reader II, respectively. All full-thickness tears of SSP-ISP tendons were detected by both readers on imaging (Fig. 1). The sensitivity for detection of partial-thickness tears was 84% and 86% for readers I and II, respectively (Figs. 2 and 3). The sensitivity, specificity, and accuracy for the diagnosis of SSC tendon tears were 80%, 89%, and 85% for reader I, and 76%, 93%, and 85% for reader II, respectively (Fig. 4). Interpretations of indirect MR arthrography for both readers were compared with arthroscopic findings and summarized in Table 2. The ICC values and 95% confidence intervals for the grading of SSP-ISP tendon tears for readers I and II were 0.934 (95% CI, 0.908–0.952) and 0.906 (95% CI,
Table 1. Diagnostic performance in the evaluation of SSP-ISP and SSC tendon tears. Reader I
SSP-ISP Any tear* FTT PTTy SSCz
Reader II
Sensitivity
Specificity
Accuracy
Sensitivity
Specificity
Accuracy
94 100 84 80
89 (24/27) – – 89 (67/75)
93 (140/150) – – 85 (127/150)
95 100 86 76
85 (23/27) – – 93 (70/75)
93 (140/150) – – 85 (127/150)
(116/123) (80/80) (36/43) (60/75)
(117/123) (80/80) (37/43) (57/75)
*Data include all kinds of SSP-ISP tendon tears, including full- and partial-thickness tears. y Data include partial-thickness tears of the SSP-ISP tendon, including articular-and bursal-sided tears. z Data include all kinds of SSC tendon tears, including full- and partial-thickness tears. FTT, full-thickness tear; PTT, partial-thickness tear.
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Fig. 1. A full-thickness tear involving the supraspinatus-infraspinatus tendon in a 62-year-old woman which was correctly diagnosed by both readers. Fat-suppressed T1W oblique coronal image (a) reveals a tendinous discontinuity with retraction of the musculotendinous junction (arrow). Arthroscopy showed a medium-sized full-thickness tear of the supraspinatus and infraspinatus tendon (b).
Fig. 2. An articular-sided partial-thickness tear involving the supraspinatus tendon in a 57-year-old woman. Fat-suppressed T1W oblique coronal (a) and oblique sagittal (b) images show focal accumulation of contrast material at the articular side of the supraspinatus tendon (arrows). Both readers interpreted the lesion as a partial-thickness tear in the supraspinatus tendon. Arthroscopy confirmed the presence of articular-sided partial-thickness tear of the supraspinatus tendon (not shown).
0.870–0.932), respectively, indicating excellent agreement between MR images and arthroscopic findings for both readers. Inter-observer agreement using k values for the detection of SSP-ISP tendon tears was 0.958 (95% CI, 0.877–1.000), whereas that for detecting SSC tendon tears was 0.783 (95% CI, 0.672–0.880), which were considered to be excellent and substantial, respectively. The ICC value for the grading of SSP-ISP tendon tears was 0.949 (95% CI, 0.929–0.963), which was considered to be excellent.
Discussion Since intra-articular contrast enhancement of the joint after intravenous injection of paramagnetic contrast
media has been reported by several authors (17–20), this non-invasive, ‘‘indirect’’ technique was proposed as an alternative method to direct MR arthrography. Compared with conventional MRI, several studies reported added diagnostic value of indirect MR arthrography. Yagci et al. compared the efficacy of indirect MR arthrography with conventional MRI for the diagnosis of rotator cuff tears, and reported that agreement between indirect MR arthrography and surgery was excellent, whereas that between conventional MRI and surgery was moderate (13). As intravenously injected contrast material diffuses into the joint space, provides reliable outlining of the surface of rotator cuff and leaks into partial tears, indirect MR arthrography detected tears more accurately than conventional MRI. In addition, the use of a fat suppression technique
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Fig. 3. A bursal-sided partial-thickness tear of the supraspinatus tendon in a 52-year-old man. Fat-suppressed T1W oblique coronal image (a) demonstrates discontinuity of the bursal fibers and intact articular fibers at the anterior portion of the supraspinatus tendon (arrow), which was interpreted as a partial-thickness tear by both readers. A thickened joint capsule in axillary recess is also noted, suggesting adhesive capsulitis (arrowhead). Arthroscopy revealed a bursal-sided partial-thickness tear of the supraspinatus tendon (b).
Fig. 4. An articular-sided partial tear at the cranial portion of subscapularis tendon in a 61-year-old woman which was correctly diagnosed by both readers. Fat-suppressed T1W axial (a) and oblique sagittal (b) images show a small hyperintense area at the articular side of the subscapularis tendon (arrows). The patient also had a large-sized full-thickness tear in the supraspinatus-infraspinatus tendon (arrowhead). Arthroscopy confirmed the presence of partial tear of the subscapularis tendon (not shown).
rescaled for smaller variations within the joint result in enhanced image contrast. Also, active exercise of the glenohumeral joint after injection of paramagnetic contrast media effectively increased the rate and degree of enhancement. Dinauer et al. reported higher sensitivity of indirect MR arthrography compared with non-contrast MRI for the diagnosis of superior glenoid labral lesions (10). This method, however, may result in interpretative error due to enhancement of extra-articular structures (9,14). As all vascularized structures and synovial structures such as bursae and tendon sheaths are enhanced regardless if it is normal or abnormal, enhanced rotator cuff due to an inflammation or granulation tissue may cause false-positive interpretations (13). On the other hand, hyperemia related to the
pathologic process will cause intense enhancement, thus help detecting inflamed tissue such as adhesive capsulitis (21). Longer examination times, discomfort when moving the symptomatic shoulder, and the lack of adequate capsular distension are also potential drawbacks of indirect MR arthrography (9,22). In previous studies of SSP-ISP tendon tears, indirect MR arthrography demonstrated high accuracy for the diagnosis of overall tears (sensitivity 67–100%, specificity 75–89%) and full-thickness tears (sensitivity 80– 100%, specificity 88–100%) (13,15,23–25). However, the exact demarcation of degenerative changes and partial-thickness tears are often difficult to identify, making the correct diagnosis difficult regardless of whether non-contrast MRI or MR arthrography is
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Table 2. Comparisons of MR arthrography and arthroscopic findings for both readers. Arthroscopy
Reader I
Reader II
Total
FTT PTT No tear FTT PTT No tear
FTT
PTT
No tear
Total
72 8 0 68 12 0 80
5 31 7 9 28 6 43
0 3 24 0 4 23 27
77 42 31 77 44 29 150
FTT, full-thickness tear; PTT, partial-thickness tear.
utilized (13,26). As a result, the diagnostic accuracy for detection of partial-thickness tears using indirect MR arthrography varied widely in previous reports, with a sensitivity of 38–80% and specificity of 62–88% (23– 25). The sensitivity and specificity in the diagnosis of SSC tendon tears using indirect MR arthrography were reported to be 64% and 75–88% by Jung et al. (15), and 67% and 85% by Oh et al. (25), respectively. We calculated the sensitivity and specificity for overall diagnostic performance including full- and partialthickness tears together for the diagnosis of SSP-ISP tendon tears. The specificity for each type of SSP-ISP tendon tear such as full- or partial-thickness tears were not calculated separately. Instead of specificity, we calculated sensitivity in terms of ‘‘detection rate’’ for each type of SSP-ISP tendon tear. As a result, if an arthroscopically-proven full-thickness tear was interpreted as a partial-thickness tear, it was regarded as a correct detection, and vice versa. As small or partial-thickness tears have increasingly become a source of surgically treatable shoulder pain (27), misinterpretation of tear grading or location may not significantly alter the treatment plan or determination of surgery in the clinical setting. To our knowledge, no data previously existed regarding the detection rate of SSP-ISP tendon tears using indirect MR arthrography. In our study, the diagnostic performance of indirect MR arthrography for overall SSP-ISP tendon tears (either full- or partial-thickness) was comparable to the currently published data, with 94–95% sensitivity and 85–89% specificity. Regarding the grading of SSPISP tendon tears, 90% and 85% of full-thickness tears were correctly graded by readers I and II, whereas 72% and 65% of partial-thickness tears were correctly graded by readers I and II, respectively. Discrepancy between sensitivity in terms of detection rates for partial-thickness tears in SSP-ISP tendons and accuracy for grading partial-thickness tears can be explained by the presence of cases of partial-thickness tears which
were interpreted as full-thickness tears. Among the 43 partial-thickness tears of the SSP-ISP tendon, five (12%) and nine (21%) cases were interpreted as fullthickness tears by readers I and II, respectively. On the other hand, among the 42 and 44 cases which were interpreted as partial-thickness tears by readers I and II, eight (19%) and 12 (27%) cases were proven to be full-thickness tears on arthroscopy, respectively. As a result, the sensitivity and specificity in terms of grading partial-thickness SSP-ISP tendon tears were 72% and 74% for reader I, and 65% and 64% for reader II, respectively, which were comparable to those of previous studies (23–25). The most probable explanation for these misgradings is that high signal intensity after contrast media injection can result from either degenerative changes or partial-thickness tears, making it difficult to correctly interpret the hyperintense area (12,13). However, the sensitivity is increased to 86% in terms of the detection rate, which contradicts previous studies which have regarded the diagnosis of partial-thickness tears using indirect MR arthrography as faulty (24,26). Thus, our results demonstrate the usefulness of indirect MR arthrography for the detection of partial-thickness SSP-ISP tendon tears and for guiding treatment plans. The sensitivity and specificity for detection of SSC tendon tears using indirect MR arthrography were 76–80% and 89–93%, which were higher than those of previous reports (15,25). This study had several limitations. First, we analyzed MR images retrospectively, and the two musculoskeletal radiologists who evaluated the images were aware that the patients had undergone arthroscopic shoulder surgery. This may have introduced a reader bias resulting in the overestimation of rotator cuff tear diagnoses and thus an increase in the sensitivity. Additionally, there may have been a patient selection bias since only patients who had undergone arthroscopic surgery were included in this study. Third, we did not include a control group of patients who underwent conventional MR prior to surgery. In the absence of control group, the value of indirect MR arthrography couldn’t be evaluated in comparison with conventional MR arthrography. Since arthroscopy is an operator-dependent modality, its interpretation is subjective, especially since precise evaluation of the SSC tendon can be difficult and may be missed on both imaging and arthroscopy (28). Notably, all the MR examinations were performed using a 3.0 T scanner only. Although 3.0 T magnets allow high image quality and may improve diagnostic performance, these systems are not widely used in some countries. Finally, assessments for findings with prognostic implications such as size of tear, degree of tendon retraction, and quality of tendon margin were not considered, as well as the side of partial-thickness tears.
726 In conclusion, indirect MR arthrography is a noninvasive, useful method of detecting of SSP-ISP and SSC tendon tears. In contrast to previous reports, indirect MR arthrography also showed excellent sensitivity in terms of detection rates for partial-thickness tears of the SSP-ISP tendon at 3.0 T. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
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