Original Article
Diffusion weighted imaging of nasopharyngeal adenoid hypertrophy
Acta Radiologica 2015, Vol. 56(5) 587–591 ! The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0284185114534107 acr.sagepub.com
Alexey Surov1, Ina Ryl1, Sylvia Bartel-Friedrich2, Andreas Wienke3 and Sabrina Ko¨sling1
Abstract Background: Diffusion-weighted imaging (DWI) could be helpful for the differentiation of malignant and benign entities. Nasopharyngeal adenoid hypertrophy (NAH) is a typical benign lesion. DWI appearances of this lesion have not been reported previously. Purpose: To identify and to analyse DWI findings of NAH. Material and Methods: We analyzed 688 MR investigations of the head performed at our institution. Magnetic resonance imaging (MRI) was obtained at a 1.5 T MRI device. Beside normal standard sequences DWI was obtained using a multislice single-shot echo-planar sequence. DWI was performed with b values of 0, 500, and 1000 s/mm2. Results: The mean whole lesion ADC value was 0.83 0.12 10–3 mm2s–1 (median, 0.82 10–3 mm2 s–1; range, 0.58–1.45 10–3 mm2 s–1). The mean ADC value of solid areas of NAH was 0.59 0.11 10–3 mm2 s–1 (range, 0.36–0.84 10–3 mm2 s–1). Conclusion: Although NAH is a benign lesion, it shows low ADC values both in childhood and in adults. This finding should be kept in mind to avoid possible misinterpretations as a malignant lesion.
Keywords Nasopharynx, adenoid hypertrophy, MRI, DWI Date received: 11 March 2014; accepted: 13 April 2014
Introduction Nasopharyngeal adenoid hypertrophy (NAH) is a typical benign lesion in childhood (1–3). It can also persist in adults (2,3). Typically, NAH manifests as a symmetrical lesion with stripes and retention cysts (1,4,5). However, NAH can also present with asymmetrical mucosal thickening and may be misdiagnosed as malignancy (1–5). As reported previously, diffusion-weighted imaging (DWI) could be helpful for the differentiation of malignant and benign entities (6). According to the literature; malignant lesions show lower values of the apparent diffusion coefficient (ADC) in comparison to benign solid or cystic lesions (6–8). Although NAH occurs frequently, DWI appearances of this lesion have not been reported previously to our best knowledge. Therefore, our aim was to analyze DWI findings of NAH in a large patient sample.
Material and Methods Patients In the time period from 2007 to 2011 MR investigations with DWI of the head were performed at our institution in 982 patients; 294 patients were excluded from the study, namely patients with known history of head or neck malignancies and patients with malignant 1 Department of Radiology, Martin-Luther-University Halle-Wittenberg, Germany 2 Department of Otorhinolaryngology, Martin-Luther-University Halle-Wittenberg, Germany 3 Department of Epidemiology, Biometry and Informatics, Martin-Luther-University Halle-Wittenberg, Germany
Corresponding author: Alexey Surov, Department of Radiology, Martin-Luther-University Halle-Wittenberg, Ernst-Grube Str. 40, 06097 Halle, Germany. Email: [email protected]
Downloaded from acr.sagepub.com at Mount Royal University on April 30, 2015
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Acta Radiologica 56(5)
lymphoma or leukemia. In addition, patients with NAHs below 5 mm in diameter or lesions with artifacts on DWI/ADC map were also excluded from the analysis. Therefore, 688 patients were included into the study. There were 360 women and 328 men with a median age of 18 years (mean age, 21.5 17.1 years; range, 0–82 years).
Magnetic resonance imaging Magnetic resonance imaging (MRI) was obtained at a 1.5 T device (Magnetom Vision Sonata Upgrade, Siemens, Erlangen, Germany). The imaging protocol included axial T2-weighted (T2W) fat-suppressed (FS) short tau inversion recovery (STIR) images, and axial T1-weighted spin echo (T1W SE) images. For DWI a multi-slice single-shot echo-planar imaging sequence was used in each case with the following parameters: TR/TE, 5900/96 ms; field of view (FOV), 250 250 mm; slice thickness, 3–5 mm; acquisition matrix, 128 128. DWI was performed with b values of 0, 500, and 1000 s/mm2. ADC maps were generated by the implemented software.
DWI analysis The slice with the largest diameter of NAH was selected for ADC calculation. In this image a polygonal region of interest (ROI) as large as possible was drawn around the margin of the lesion (whole lesion measurement) without risking partial volume effects. Next, a round ROI was placed within the solid part of NAH avoiding the cystic parts (ADC values of solid areas). The ADC value was measured on ADC maps as well as was calculated after the formula: ADC (mm2 s–1 10–3) ¼ [ln(S0/S1000)]/1000 by measuring on b ¼ 0 and b ¼ 1000 images. The estimated ADC values (10–3 mm2 s–1) were categorized as follows: very low, 0.70 0.90 1.20 mm2 s–1.
Statistical analysis For statistical analysis the SPSS statistical software package was used (SPSS 17.0, SPSS Inc., Chicago IL, USA). Collected data were evaluated by means of descriptive statistics (absolute and relative frequencies). Categorical variables were expressed as percentages. Analyses of lesion specific outcomes (size, signal intensity, enhancement characteristics and ADC values) were performed by means of generalized linear mixed models. P < 0.05 was taken to indicate statistical significance in all instances. P values were adjusted for multiple testing by using the Bonferroni correction.
Results The mean size of the analyzed NAH was 22.8 4.5 mm in cranio-caudal, 30.9 5.3 mm in left-right, and 14.2 4.0 mm in anterior-posterior direction. The mean NAH ADC value of whole lesions’ measurements was 0.83 0.12 10–3 mm2 s–1 (median, 0.82 10–3 mm2 s–1; range, 0.58–1.45 10–3 mm2 s–1) (Figs. 1–4). Most of the identified lesions showed low or very low ADC values (Table 1). ADC values of solid NAH areas showed lower values in comparison to the measurements of the whole lesion (Table 2), ranging from 0.36 to 0.84 10–3 mm2 s–1 (mean value, 0.59 0.11 10–3 mm2 s–1). The distribution of ADC values dependent on age is shown in Table 3. Lowest ADC values were identified in the age groups aged 10–29 years. The ADC values were significantly higher in the group aged 60–69 years in comparison to the age groups from 0 to 59 years (Table 3). In addition, the ADC values of the groups aged 10–29 years were significantly lower in comparison to the groups aged 40–59 years and in comparison to the group aged over 70 years. Most ADC values of solid NAH areas were very low, in the range of 0.36– 0.7 10–3 mm2 s–1. The ADC values were significantly higher in the group aged 60–69 years in comparison to the age groups from 0 to 59 years (Table 3).
Discussion Some author stress the importance of DWI in the radiological characterization of a lesion’s dignity in the head and neck region (6–8). DWI should be helpful to differentiate malignant from benign lesions (8,9). In the investigations of Wang et al. malignant tumors showed lower ADC values than benign disorders (6). Other authors have confirmed these data (10–12). According to the literature, mean ADC values varied in benign lesions from 0.89 10–3 mm2 s–1 in scleromas to 1.75 10–3 mm2 s–1 in venous malformations, whereas the mean ADC values of malignant tumors differed from 0.78 10–3 mm2 s–1 in rhabdomyosarcoma to 1.20 10–3 mm2 s–1 in mucoepidermoid carcinoma (8). Wang et al. found a mean ADC value of 0.66 10–3 mm2 s–1 in malignant lymphomas, while squamous and adenoid carcinomas had 1.13 10–3 mm2 s–1 (6). In their study, benign solid lesions presented with a mean ADC value of 1.56 10–3 mm2 s–1 (6). In addition, the authors proposed a diagnostic scale of ADC values to predict malignancy. ADC values 0.65 10–3 mm2 s–1 showed a positive predictive value of malignancy of 100% and ADC values 1.01 10–3 mm2 s–1 had a positive predictive value of malignancy of 90% (6). However, these ADC categorizations cannot be applied to all lesions. Some classic benign lesions show low ADC values. For example, Ikeda et al. studied DWI findings
Downloaded from acr.sagepub.com at Mount Royal University on April 30, 2015
Surov et al.
589
Fig. 1. NAH (arrows) in a 6-year-old child. (a) T2W image (STIR) showing a nasopharyngeal mass slightly hyperintense in comparison to the pterygoid muscles. Small cysts are seen within the lesion. (b) On ADC map the lesion shows a low signal intensity. (c) The calculated ADC value of the whole lesion is 0.89 10–3 mm2 s–1. (d) The calculated ADC value of a solid area of the lesion is 0.65 10–3 mm2 s–1.
Fig. 2. NAH (arrows) in a 16-year-old patient. (a) On T2W fat-saturated image the mass is hyperintense in comparison to the pterygoid muscles. (b) NAH has a low signal intensity on ADC map. The calculated ADC value of the whole lesion is 0.80 10–3 mm2 s–1. (c) The calculated ADC value of a solid area of the lesion is 0.47 10–3 mm2 s–1.
of Warthin tumors of the parotid gland (13). The mean ADC of this benign entity was significantly lower than that of malignant parotid tumors (13). From other benign lesions such as cholesteatomas, also low ADC values are known (14,15). Although NAH is a frequent lesion, we could not find reports about DWI characteristics of this entity.
In our study, ADC values of NAH were lower as those previously reported in different carcinomas of the head and neck region. This finding may be related to the fact that NAH may be of high cellularity. Our analysis showed also that ADC values tend to increase with age, but they remain relatively low. In addition, all NAH contained solid areas with very
Downloaded from acr.sagepub.com at Mount Royal University on April 30, 2015
590
Acta Radiologica 56(5)
Fig. 3. NAH (arrows) in a 43-year-old patient. (a) On T2W fat-saturated image the mass is hyperintense in comparison to the pterygoid muscles. (b) NAH has a low signal intensity on ADC map. The calculated ADC value of the whole lesion is 0.89 10–3 mm2 s–1. (c) The calculated ADC value of a solid area of the lesion is 0.58 10–3 mm2 s–1.
Fig. 4. NAH (arrows) in a 58-year-old patient. (a) On T2W fat saturated image the mass is hyperintense in comparison to the pterygoid muscles. (b) NAH has a low signal intensity on ADC map. The calculated ADC value of the whole lesion is 0.77 10–3 mm2 s–1. (c) The calculated ADC value of a solid area of the lesion is 0.59 10–3 mm2 s–1.
Table 1. Distribution of ADC values of NAH (whole lesion measurment).
ADC grade
Cases (n)
Frequency (%)
ADC (M SD) ( 10–3 mm2 s–1)
Very low Low Moderate High
78 480 107 23
11.3 69.8 15.6 3.3
0.67 0.03 0.81 0.05 0.96 0.05 1.23 0.11
low ADC values. Because of this behavior, NAH can be misinterpreted as carcinoma or malignant lymphoma, especially in patients aged more than 40 years. To the best of our knowledge this observation has not been documented until now.
Table 2. Distribution of the ADC of NAH (solid parts measurement). ADC grade
Cases (n)
Frequency (%)
ADC (M SD) (10–3 mm2 s–1)
Very low Low
630 58
91.6 8.4
0.57 0.07 0.75 0.04
Our analysis has several limitations. First, it is retrospective. Second, the identified lesions were not investigated histopathologically. In conclusion, although NAH is a benign lesion, it shows low ADC values both in childhood and in adults. This finding should be kept in mind to avoid possible misinterpretations as a malignant lesion.
Downloaded from acr.sagepub.com at Mount Royal University on April 30, 2015
0.67 0.10
0.98 0.25 P ¼ 0.023 vs. 10–19 years; P ¼ 0.018 vs. 20–29 years
591
>70
Surov et al. Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
0.73 0.24
1.04 0.19 0.88 0.14 P ¼ 0.001 vs. 60–69 years 0.86 0.15 P ¼ 0.001 vs. 60–69 years 0.83 0.11 P ¼ 0.001 vs. 60–69 years
0.80 0.08 P ¼ 0.001 vs. 60–69 years; P ¼ 0.017 vs. 40–49 years; P ¼ 0.01 vs. 50–59 years 0.59 0.09 P ¼ 0.001 vs. 60–69 years 0.81 0.09 P ¼ 0.001 vs. 60–69 years; P ¼ 0.028 vs. 40–49 years; P ¼ 0.015 vs. 50–59 years 0.58 0.09 P ¼ 0.001 vs. 60–69 years 0.83 0.12 P ¼ 0.001 vs. 60–69 years Whole lesion measurement (M SD)
0.60 0.09 P ¼ 0.001 vs. 60–69 years
0.58 0.11 P ¼ 0.001 vs. 60–69 years
0.58 0.10 P ¼ 0.001 vs. 60–69 years
0.62 0.14 P ¼ 0.017 vs. 60–69 years
60–69 50–59 40–49 30–39 20–29 10–19 0–9
Solid areas measurement (M SD)
Age groups (years)
ADC (10 mm /s)
2 –3
Table 3. Estimated ADC values of NAH in dependence on age groups.
References 1. Bhatia KSS, King AD, Vlantis AC, et al. Nasopharyngeal mucosa and adenoids: appearance at MR imaging. Radiology 2012;263:437–443. 2. Ko¨sling S, Knipping S, Hofmockel T. Imaging of nasopharyngeal diseases. Radiologe 2009;49:17–26. 3. Vogler RC, Wippold FJ, Pilgram TK. Age-specific size of the normal adenoid pad on magnetic resonance imaging. Clin Otolaryngol 2000;25:392–395. 4. Fujiyoshi T, Watanabe T, Ichimiya I, et al. Functional architecture of the nasopharyngeal tonsil. Am J Otolaryngol 1989;10:124–131. 5. King AD, Vlantis AC, Tsang RK, et al. Magnetic resonance imaging for the detection of nasopharyngeal carcinoma. Am J Neuroradiol 2006;27:1288–1291. 6. Wang J, Takashima S, Takayama F, et al. Head and neck lesions: characterization with diffusion-weigted echoplanar MR imaging. Radiology 2001;220:621–630. 7. Thoeny HC, Ross BD. Predicting and monitoring cancer treatment response with diffusion-weighted MRI. J Magn Reson Imaging 2010;32:2–16. 8. Abdel Razek AAK, Gaballa G, et al. Characterization of pediatric head and neck masses with diffusion-weighted MR imaging. Eur Radiol 2009;19:201–208. 9. Sasaki M, Eida S, Sumi M, et al. Apparent diffusion coefficient for sinonasal diseases: differentiation of benign and malignant lesions. Am J Neuroradiol 2011; 32:1256–1262. 10. Fong D, Bhatia KSS, Yeung D, et al. Diagnostic accuracy of diffusion-weighted MR imaging for nasopharyngeal carcinoma, head and neck lymphoma and squamous cell carcinoma at the primary site. Oral Oncol 2010;46: 603–606. 11. Srinivasan A, Dvorak R, Perni K, et al. Differentiation of benign and malignant pathology in the head and neck using 3T apparent diffusion coefficient values: early experience. Am J Neuroradiol 2008;29:40–44. 12. Eida S, Sumi M, Sakihama N. Apparent diffusion coefficient mapping of salivary gland tumors: prediction of the benignancy and malignancy. Am J Neuroradiol 2011; 28:116–121. 13. Ikeda M, Motoori K, Hanazawa T, et al. Warthin tumor of the parotid gland: diagnostic value of MR imaging with histopathologic correlation. Am J Neuroradiol 2004;25:1256–1262. 14. Thiriat S, Riehm S, Kremer S, et al. Apparent diffusion coefficient values of middle ear cholesteatoma differ from abscess and cholesteatoma and mixed infection. Am J Neuroradiol 2009;30:1123–1126. 15. Lingam RK, Khatri P, Hughes J, et al. Apparent diffusion coefficients for detection of postoperative middle ear cholesteatoma on non-echo-planar diffusion-weighted images. Radiology 2013;269:504–510.
Downloaded from acr.sagepub.com at Mount Royal University on April 30, 2015
Diffusion weighted imaging of nasopharyngeal adenoid hypertrophy
Acta Radiologica 2015, Vol. 56(5) 587–591 ! The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0284185114534107 acr.sagepub.com
Alexey Surov1, Ina Ryl1, Sylvia Bartel-Friedrich2, Andreas Wienke3 and Sabrina Ko¨sling1
Abstract Background: Diffusion-weighted imaging (DWI) could be helpful for the differentiation of malignant and benign entities. Nasopharyngeal adenoid hypertrophy (NAH) is a typical benign lesion. DWI appearances of this lesion have not been reported previously. Purpose: To identify and to analyse DWI findings of NAH. Material and Methods: We analyzed 688 MR investigations of the head performed at our institution. Magnetic resonance imaging (MRI) was obtained at a 1.5 T MRI device. Beside normal standard sequences DWI was obtained using a multislice single-shot echo-planar sequence. DWI was performed with b values of 0, 500, and 1000 s/mm2. Results: The mean whole lesion ADC value was 0.83 0.12 10–3 mm2s–1 (median, 0.82 10–3 mm2 s–1; range, 0.58–1.45 10–3 mm2 s–1). The mean ADC value of solid areas of NAH was 0.59 0.11 10–3 mm2 s–1 (range, 0.36–0.84 10–3 mm2 s–1). Conclusion: Although NAH is a benign lesion, it shows low ADC values both in childhood and in adults. This finding should be kept in mind to avoid possible misinterpretations as a malignant lesion.
Keywords Nasopharynx, adenoid hypertrophy, MRI, DWI Date received: 11 March 2014; accepted: 13 April 2014
Introduction Nasopharyngeal adenoid hypertrophy (NAH) is a typical benign lesion in childhood (1–3). It can also persist in adults (2,3). Typically, NAH manifests as a symmetrical lesion with stripes and retention cysts (1,4,5). However, NAH can also present with asymmetrical mucosal thickening and may be misdiagnosed as malignancy (1–5). As reported previously, diffusion-weighted imaging (DWI) could be helpful for the differentiation of malignant and benign entities (6). According to the literature; malignant lesions show lower values of the apparent diffusion coefficient (ADC) in comparison to benign solid or cystic lesions (6–8). Although NAH occurs frequently, DWI appearances of this lesion have not been reported previously to our best knowledge. Therefore, our aim was to analyze DWI findings of NAH in a large patient sample.
Material and Methods Patients In the time period from 2007 to 2011 MR investigations with DWI of the head were performed at our institution in 982 patients; 294 patients were excluded from the study, namely patients with known history of head or neck malignancies and patients with malignant 1 Department of Radiology, Martin-Luther-University Halle-Wittenberg, Germany 2 Department of Otorhinolaryngology, Martin-Luther-University Halle-Wittenberg, Germany 3 Department of Epidemiology, Biometry and Informatics, Martin-Luther-University Halle-Wittenberg, Germany
Corresponding author: Alexey Surov, Department of Radiology, Martin-Luther-University Halle-Wittenberg, Ernst-Grube Str. 40, 06097 Halle, Germany. Email: [email protected]
Downloaded from acr.sagepub.com at Mount Royal University on April 30, 2015
588
Acta Radiologica 56(5)
lymphoma or leukemia. In addition, patients with NAHs below 5 mm in diameter or lesions with artifacts on DWI/ADC map were also excluded from the analysis. Therefore, 688 patients were included into the study. There were 360 women and 328 men with a median age of 18 years (mean age, 21.5 17.1 years; range, 0–82 years).
Magnetic resonance imaging Magnetic resonance imaging (MRI) was obtained at a 1.5 T device (Magnetom Vision Sonata Upgrade, Siemens, Erlangen, Germany). The imaging protocol included axial T2-weighted (T2W) fat-suppressed (FS) short tau inversion recovery (STIR) images, and axial T1-weighted spin echo (T1W SE) images. For DWI a multi-slice single-shot echo-planar imaging sequence was used in each case with the following parameters: TR/TE, 5900/96 ms; field of view (FOV), 250 250 mm; slice thickness, 3–5 mm; acquisition matrix, 128 128. DWI was performed with b values of 0, 500, and 1000 s/mm2. ADC maps were generated by the implemented software.
DWI analysis The slice with the largest diameter of NAH was selected for ADC calculation. In this image a polygonal region of interest (ROI) as large as possible was drawn around the margin of the lesion (whole lesion measurement) without risking partial volume effects. Next, a round ROI was placed within the solid part of NAH avoiding the cystic parts (ADC values of solid areas). The ADC value was measured on ADC maps as well as was calculated after the formula: ADC (mm2 s–1 10–3) ¼ [ln(S0/S1000)]/1000 by measuring on b ¼ 0 and b ¼ 1000 images. The estimated ADC values (10–3 mm2 s–1) were categorized as follows: very low, 0.70 0.90 1.20 mm2 s–1.
Statistical analysis For statistical analysis the SPSS statistical software package was used (SPSS 17.0, SPSS Inc., Chicago IL, USA). Collected data were evaluated by means of descriptive statistics (absolute and relative frequencies). Categorical variables were expressed as percentages. Analyses of lesion specific outcomes (size, signal intensity, enhancement characteristics and ADC values) were performed by means of generalized linear mixed models. P < 0.05 was taken to indicate statistical significance in all instances. P values were adjusted for multiple testing by using the Bonferroni correction.
Results The mean size of the analyzed NAH was 22.8 4.5 mm in cranio-caudal, 30.9 5.3 mm in left-right, and 14.2 4.0 mm in anterior-posterior direction. The mean NAH ADC value of whole lesions’ measurements was 0.83 0.12 10–3 mm2 s–1 (median, 0.82 10–3 mm2 s–1; range, 0.58–1.45 10–3 mm2 s–1) (Figs. 1–4). Most of the identified lesions showed low or very low ADC values (Table 1). ADC values of solid NAH areas showed lower values in comparison to the measurements of the whole lesion (Table 2), ranging from 0.36 to 0.84 10–3 mm2 s–1 (mean value, 0.59 0.11 10–3 mm2 s–1). The distribution of ADC values dependent on age is shown in Table 3. Lowest ADC values were identified in the age groups aged 10–29 years. The ADC values were significantly higher in the group aged 60–69 years in comparison to the age groups from 0 to 59 years (Table 3). In addition, the ADC values of the groups aged 10–29 years were significantly lower in comparison to the groups aged 40–59 years and in comparison to the group aged over 70 years. Most ADC values of solid NAH areas were very low, in the range of 0.36– 0.7 10–3 mm2 s–1. The ADC values were significantly higher in the group aged 60–69 years in comparison to the age groups from 0 to 59 years (Table 3).
Discussion Some author stress the importance of DWI in the radiological characterization of a lesion’s dignity in the head and neck region (6–8). DWI should be helpful to differentiate malignant from benign lesions (8,9). In the investigations of Wang et al. malignant tumors showed lower ADC values than benign disorders (6). Other authors have confirmed these data (10–12). According to the literature, mean ADC values varied in benign lesions from 0.89 10–3 mm2 s–1 in scleromas to 1.75 10–3 mm2 s–1 in venous malformations, whereas the mean ADC values of malignant tumors differed from 0.78 10–3 mm2 s–1 in rhabdomyosarcoma to 1.20 10–3 mm2 s–1 in mucoepidermoid carcinoma (8). Wang et al. found a mean ADC value of 0.66 10–3 mm2 s–1 in malignant lymphomas, while squamous and adenoid carcinomas had 1.13 10–3 mm2 s–1 (6). In their study, benign solid lesions presented with a mean ADC value of 1.56 10–3 mm2 s–1 (6). In addition, the authors proposed a diagnostic scale of ADC values to predict malignancy. ADC values 0.65 10–3 mm2 s–1 showed a positive predictive value of malignancy of 100% and ADC values 1.01 10–3 mm2 s–1 had a positive predictive value of malignancy of 90% (6). However, these ADC categorizations cannot be applied to all lesions. Some classic benign lesions show low ADC values. For example, Ikeda et al. studied DWI findings
Downloaded from acr.sagepub.com at Mount Royal University on April 30, 2015
Surov et al.
589
Fig. 1. NAH (arrows) in a 6-year-old child. (a) T2W image (STIR) showing a nasopharyngeal mass slightly hyperintense in comparison to the pterygoid muscles. Small cysts are seen within the lesion. (b) On ADC map the lesion shows a low signal intensity. (c) The calculated ADC value of the whole lesion is 0.89 10–3 mm2 s–1. (d) The calculated ADC value of a solid area of the lesion is 0.65 10–3 mm2 s–1.
Fig. 2. NAH (arrows) in a 16-year-old patient. (a) On T2W fat-saturated image the mass is hyperintense in comparison to the pterygoid muscles. (b) NAH has a low signal intensity on ADC map. The calculated ADC value of the whole lesion is 0.80 10–3 mm2 s–1. (c) The calculated ADC value of a solid area of the lesion is 0.47 10–3 mm2 s–1.
of Warthin tumors of the parotid gland (13). The mean ADC of this benign entity was significantly lower than that of malignant parotid tumors (13). From other benign lesions such as cholesteatomas, also low ADC values are known (14,15). Although NAH is a frequent lesion, we could not find reports about DWI characteristics of this entity.
In our study, ADC values of NAH were lower as those previously reported in different carcinomas of the head and neck region. This finding may be related to the fact that NAH may be of high cellularity. Our analysis showed also that ADC values tend to increase with age, but they remain relatively low. In addition, all NAH contained solid areas with very
Downloaded from acr.sagepub.com at Mount Royal University on April 30, 2015
590
Acta Radiologica 56(5)
Fig. 3. NAH (arrows) in a 43-year-old patient. (a) On T2W fat-saturated image the mass is hyperintense in comparison to the pterygoid muscles. (b) NAH has a low signal intensity on ADC map. The calculated ADC value of the whole lesion is 0.89 10–3 mm2 s–1. (c) The calculated ADC value of a solid area of the lesion is 0.58 10–3 mm2 s–1.
Fig. 4. NAH (arrows) in a 58-year-old patient. (a) On T2W fat saturated image the mass is hyperintense in comparison to the pterygoid muscles. (b) NAH has a low signal intensity on ADC map. The calculated ADC value of the whole lesion is 0.77 10–3 mm2 s–1. (c) The calculated ADC value of a solid area of the lesion is 0.59 10–3 mm2 s–1.
Table 1. Distribution of ADC values of NAH (whole lesion measurment).
ADC grade
Cases (n)
Frequency (%)
ADC (M SD) ( 10–3 mm2 s–1)
Very low Low Moderate High
78 480 107 23
11.3 69.8 15.6 3.3
0.67 0.03 0.81 0.05 0.96 0.05 1.23 0.11
low ADC values. Because of this behavior, NAH can be misinterpreted as carcinoma or malignant lymphoma, especially in patients aged more than 40 years. To the best of our knowledge this observation has not been documented until now.
Table 2. Distribution of the ADC of NAH (solid parts measurement). ADC grade
Cases (n)
Frequency (%)
ADC (M SD) (10–3 mm2 s–1)
Very low Low
630 58
91.6 8.4
0.57 0.07 0.75 0.04
Our analysis has several limitations. First, it is retrospective. Second, the identified lesions were not investigated histopathologically. In conclusion, although NAH is a benign lesion, it shows low ADC values both in childhood and in adults. This finding should be kept in mind to avoid possible misinterpretations as a malignant lesion.
Downloaded from acr.sagepub.com at Mount Royal University on April 30, 2015
0.67 0.10
0.98 0.25 P ¼ 0.023 vs. 10–19 years; P ¼ 0.018 vs. 20–29 years
591
>70
Surov et al. Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
0.73 0.24
1.04 0.19 0.88 0.14 P ¼ 0.001 vs. 60–69 years 0.86 0.15 P ¼ 0.001 vs. 60–69 years 0.83 0.11 P ¼ 0.001 vs. 60–69 years
0.80 0.08 P ¼ 0.001 vs. 60–69 years; P ¼ 0.017 vs. 40–49 years; P ¼ 0.01 vs. 50–59 years 0.59 0.09 P ¼ 0.001 vs. 60–69 years 0.81 0.09 P ¼ 0.001 vs. 60–69 years; P ¼ 0.028 vs. 40–49 years; P ¼ 0.015 vs. 50–59 years 0.58 0.09 P ¼ 0.001 vs. 60–69 years 0.83 0.12 P ¼ 0.001 vs. 60–69 years Whole lesion measurement (M SD)
0.60 0.09 P ¼ 0.001 vs. 60–69 years
0.58 0.11 P ¼ 0.001 vs. 60–69 years
0.58 0.10 P ¼ 0.001 vs. 60–69 years
0.62 0.14 P ¼ 0.017 vs. 60–69 years
60–69 50–59 40–49 30–39 20–29 10–19 0–9
Solid areas measurement (M SD)
Age groups (years)
ADC (10 mm /s)
2 –3
Table 3. Estimated ADC values of NAH in dependence on age groups.
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