State of the art imaging of typical and atypical adrenal adenomas.

Transcription

1 State of the art imaging of typical and atypical adrenal adenomas. Poster No.: C-0896 Congress: ECR 2012 Type: Educational Exhibit Authors: N. LAUNAY, S. Silvera, F. Tissier, L. Groussin, A. Oudjit, A Schull, M.-C. VACHER-LAVENU, X. Bertagna, P. Legmann ; 1 2 Paris/FR, Paris cedex 14/FR Keywords: Metastases, Endocrine disorders, Comparative studies, MRDiffusion/Perfusion, MR, CT-High Resolution, Adrenals DOI: /ecr2012/C-0896 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 46

2 Learning objectives To learn the diagnostic strategy of adrenal incidentalomas, most of which are benign adrenocortical adenomas. To study the imaging, clinical and pathological features of atypical adrenocortical adenomas (A.A.A.) and to compare their imaging features with those of adrenal metastases and adrenocortical carcinomas. To learn state-of-the-art techniques, which are under evaluation, to distinguish A.A.A. from adrenal malignant tumors : spectroscopy MRI, diffusion MRI and dynamic contrast enhanced MRI. Background The majority of adrenal incidentalomas (detected on about 5-8% of all abdominal imaging) are adrenocortical adenomas. The diagnostic strategy is well codified for adrenocortical adenomas (1, 2, 3, 4, 5, 6) and relies on the detection of intracellular lipid (using noncontrast CT or chemical shift MRI) and on the measurement of contrast washout kinetics on multiphasic CT. However, a sub-group of adrenocortical adenomas does not respond to described criteria of benignity (7,8): these atypical adenomas are considered as malignant tumors and are surgically removed. Being able to accurately identify an atypical adrenocortical adenomas (A.A.A.) would avoid many unnecessary surgeries. We retrospectively reviewed A.A.A. explored in our department. Imaging findings with key points were described and compared to those of adrenal metastasis and adrenocortical carcinomas. The role of state-of-the-art imaging techniques in the diagnosis of adrenocortical adenomas is highlighted. Imaging findings OR Procedure details Diagnostic strategy of adrenal incidentalomas.(1, 3) 3 important questions: Did the patient undergo any prior cross-sectional imaging? If the lesion is stable for 6 months, it is almost certainly benign. Page 2 of 46

3 If the images show significant growth of the lesion, it is almost certainly malignant. Are hormone tests results available? Hormonal testing helps excluding hyperfunctioning diseases and is the method most commonly used to diagnose pheochromocytomas. Are there any malignant extra adrenal lesion? If there is no extra adrenal lesion, in the majority of cases the adrenal lesion would be benign. If such lesions exist, in at least 30% of the cases, the adrenal lesion would be malignant. Eliminate simple diagnosis: Myelolipomas (Fig. 1) are benign tumors, composed of mature adipose tissue. Most myelolipomas show macroscopic fat on unenhanced CT. Their spontaneous density is less than -30 HU. They usually are hyperintense in T1 and T2 sequences. They show a loss of signal in fat sat sequences. Page 3 of 46

4 Fig. 1: Myelolipoma Spontaneous density of -94 UH References: Legmann P. J Radiol 2009;90; Fig. 1 Hematomas (Fig. 2) are of traumatic origin in 1 to 2% of the cases. Spontaneous density depends on the age of the hematoma. The spontaneous density for a recent hematoma ranges from 50 HU to 60 HU. They usually show no enhancement. If an hematoma shows enhancement, an underlying lesion must be suspected. Page 4 of 46

5 Fig. 2: Hematoma Spontaneous density of 56 UH. References: Legmann P. J Radiol 2009;90; Fig. 2 Adrenal cysts (Fig 3 and 4) are rare and usually asymptomatic. Their spontaneous density ranges from 0 to 20 HU with wall thickness of less than 3 mm. They usually show no enhancement. On MR images, adrenal cysts are hypointense in T1 sequences and hyperintense in T2 sequences. Page 5 of 46

6 Fig. 3: Enhanced CT, the density of the lesion is 18 UH : cystic mass with thin parois with no enhancement. References: Legmann P. J Radiol 2009;90; Fig. 3 Page 6 of 46

7 Fig. 4: TI sequence with injection : lesion in hyposignal with no enhancement. References: Legmann P. J Radiol 2009;90; Fig. 4 Imaging algorithm for adrenal lesions characterisation.(fig 11): Step 1: Lesion size estimation. For all lesions larger than or equal to 6 cm in diameter, surgical removal is recommended. For lesions smaller than 6 cm, further investigations by unenhanced CT are necessary. Step 2: Spontaneous density (SD) measurement. Page 7 of 46

8 A spontaneous density of less than or equal to 10 HU is diagnostic of a lipid-rich adrenocortical adenoma. (Sensibility: 71%, Specificity: 98%) (Fig 5). If the spontaneous density is more than 10 HU, then further investigations by contrast-enhanced CT at 1 minute and 10 minutes are required. Fig. 5: Left adrenal adenoma (Spontaneous density : 0 UH) References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 5 Step 3: Evaluation of absolute wash out (AWO) and relative wash out (RWO). (Fig 6) Page 8 of 46

9 Fig. 6: Evaluation of absolute and relative wash out References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 6 An absolute wash out of more than or equal to 60% or a relative wash out of more than or equal to 40% is diagnostic of an adrenocortical adenoma. (Sensibility: 98%, Specificity: 92%).(Fig 7) If the absolute wash out is of less than 60% or the relative wash out is less than 40%, further investigations by MR imaging (including in phase and out of phase sequences) are needed. Fig. 7: Right adrenal adenoma. Spontaneous density : 41 UH Enhanced density at 1 min : 90 UH Delayed density at 10 min : 55 UH Absolute Wash Out : 71.4% (>60%) References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 7 Step 4: quantitative analysis of signal intensity loss. (Fig 8) Page 9 of 46

10 Fig. 8: Evaluation of loss of signal in chemical shift sequences References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 8 Signal loss of more than or equal to 20% on out of phase images, is characteristic of an adrenocortical adenoma (Sensibility: 80-96%, Specificity: %).(Fig 9, Fig 10) If the signal loss is less than 20%, the lesion still remains indeterminate: further investigations by PET-CT may be realised or percutaneous biopsy/ surgical removal of the lesion followed by a histologic analysis. Fig. 9: Left adrenal adenoma, with signal loss between in phase and out of phase sequences of more than 20%. References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 9 Page 10 of 46

11 Fig. 10: Well limited mass with characteristic orange color : adrenal adenoma References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 10 Page 11 of 46

12 Fig. 11: Diagnostic strategy of adrenal incidentalomas References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 11 Atypical adrenal adenomas (A.A.A.): clinical and imaging features A sub-group of adrenal adenomas does not respond to described criteria of benignity: these atypical adenomas are considered as malignant tumors and are surgically removed. A.A.A. were defined as adrenal masses with a histological diagnosis of adrenocortical adenoma with a spontaneous density > 10 HU, an absolute wash out < 60 % and a signal loss in chemical shift sequences < 20% or of large size and heterogeneous. We retrospectively reviewed A.A.A. explored in our department and compared their imaging features with those of adrenal metastasis and adrenocortical carcinomas. Imaging findings with key points were described. Finally 16 atypical adrenocortical adenomas, 27 metastases and 37 adrenal cortical carcinomas were reviewed. Page 12 of 46

13 A.A.A. - Key points: The mean age of the patients with A.A.A. was 64 years ± 8.3 (Standard deviation). 43.8% of the atypical adenomas were non-secreting adenomas, 43.8% were pre-toxic adenomas and 12.5% were Cushing's adenomas. Their mean diameter was 4.8 cm (range, cm). Their limits were regular and well-defined (100%). Most of them were heterogeneous (94%), presenting: calcifications (81%) (Fig. 13, 18, 19) macroscopic fat (62.5%) «cystic» areas (31.3%) (Fig. 14) hemorrhagic areas (12.5%). (Fig. 15, 16, 17) None of them presented solid tissue nodules and walls were rare (18.8%). 9 adrenocortical adenomas were examined by PET-CT: one adenoma with a Weiss score of 2, showed a high uptake value of 10.3, while the other 8 adenomas did not show significant uptake. On MR images, A.A.A presented various signal intensities in T1 and T2 sequences (8 cases), as well as in diffusion sequences (3 cases). 2 2 They presented high ADC's values (2 cases: 1379 mm /s and 2305 mm /s). At pathologic examinations, 81.2% of the atypical adrenocortical adenomas presented a Weiss score of 0, 12.5% presented a Weiss score of 1 and 6.2% presented a Weiss score of 2. Adrenal tumors with a Weiss score between 0 and 2 are considered to be benign, while adrenal tumors with a Weiss score of more than 3 are considered to be malignant (9). Histologically, none of them contained areas of necrosis. Page 13 of 46

14 Fig. 13: 42-year-old woman with a Cushing syndrome. Unenhanced CT image shows a left heterogeneous adrenal mass containing calcifications, macroscopic fat and hemorrhage. Anatomopathology: adrenal cortical adenoma with hemorrhagic areas. References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 13 Page 14 of 46

15 Fig. 14: 42-year-old woman with a Cushing syndrome. Axial T1 weighted image shows a left heterogeneous adrenal mass with normal signal intensity. Axial T2 weighted fat sat image shows a cystic component (area with low T1 signal intensity and high T2 signal intensity). Anatomopathology: adrenal cortical adenoma with hemorrhage. References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 14 Page 15 of 46

16 Fig. 15: Adrenal cortical adenoma with large fibrino-hemorrhagic areas. Unenhanced CT image shows a left adrenal lesion with a hemorrhagic area. References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 15 Fig. 16: Adrenal cortical adenoma with large fibrino-hemorrhagic areas. Macroscopy: lobulated yellow intra-adrenal tumor containing dark red focal areas. References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 16 Page 16 of 46

17 Fig. 17: Adrenal cortical adenoma with large fibrino-hemorrhagic areas. Histology: proliferation of adrenal cortical cells in well vascularized interstitial tissue. No sign of malignancy. References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 17 Page 17 of 46

18 Fig. 18: Unenhanced CT: left heterogeneous adrenal mass containing calcifications. References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 18 Page 18 of 46

19 Fig. 19: Macroscopy : orange-yellow mass with maroon areas. Histology : adrenal cortical adenoma with large areas of hemorrhage. References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 19 Atypical adrenocortical adenomas versus adrenal metastases Men were significantly more affected by metastases than women The mean age of the patients with metastases was 61 years ± 8.2. Margins were significantly better defined for adenomas than for metastases. 62.5% of adrenal adenomas presented macroscopic fat, while none of the metastases contained macroscopic fat. Calcifications were frequent in adrenal adenomas, while none of the metastases contained calcifications. ADC values were higher for atypical adenomas (spectroscopy MRI available for 2 adenomas) than for adrenal metastases (spectroscopy MRI available for 3 metastasis), but not significantly. Page 19 of 46

20 Maximum standardized uptake values (SUVmax) were lower for adenomas than for metastases. Fig. 20: 62-year-old man with known hepatocellular carcinoma. Enhanced phase CT image shows heterogeneous enhancement. Anatomopathology: adrenal metastases of a hepatocellular carcinoma. References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 20 Page 20 of 46

21 Fig. 21: 56-year-old man with known chest carcinoma. Enhanced phase CT image shows bilateral adrenal masses, with poorly defined margins and homogeneous enhancement. Anatomopathology: adrenal metastases of a chest carcinoma. References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 21 Atypical adrenocortical adenomas versus adrenocortical carcinomas Age was significantly higher for adrenocortical adenomas (64 years ± 8,3) than for adrenal cortical carcinomas (49,6 years ± 17,6) (p<0,05). Page 21 of 46

22 There was no difference in sex-ratio. In our series, no adrenocortical adenomas secreted androgen or estrogen. 41% of the adrenocortical carcinomas with biologically available data (27 cases) were non-secreting. 18.5% secreted both androgen and steroid hormones, 15% were "pre-toxic", 15% caused Cushing syndrome, 7.4% secreted only androgen, 3.7% secreted estrogen. (Fig. 22). Mean diameter of adrenal cortical carcinomas was 8 cm ± 3.7. Their maximum diameters were significantly larger for adrenal cortical carcinomas than for adrenal adenomas. All adenomas had well defined margins, while only 41.2% of adrenal cortical carcinomas did. 62.5% of the adrenal adenomas presented macroscopic fat, while none of the adrenal cortical carcinomas did. Histologically, 73% of these masses contained areas of necrosis. SUV max were significantly lower for adenomas than for adrenal cortical carcinomas. ADC values were significantly higher for atypical adenomas than for adrenal cortical carcinomas (spectroscopy MRI available for 6 adrenocortical carcinomas). Page 22 of 46

23 Fig. 22: 53-year-old woman with Cushing syndrome. Dynamic enhanced phase CT image shows a left adrenal mass with irregular and poorly defined margins with homogeneous, and little contrast enhancement. Anatomopathology: left adrenal cortical carcinoma. References: N. LAUNAY; PARIS, Paris, FRANCE Fig. 22 Page 23 of 46

24 Imaging features of adrenal cortical carcinomas were similar to those described in previous studies (10). Atypical adrenocortical adenomas versus malignant masses All atypical adrenocortical adenomas were well-defined. 62.5% of adrenocortical adenomas presented macroscopic fat, while none of the malignant masses did. Calcifications, hemorrhagic areas, heterogeneity and the presence of walls had no diagnostic value for or against malignancy. Apparent diffusion coefficient (ADC) values were significantly higher in the adenomas than in the malignant tumors. Maximum standardized uptake values (SUVmax) were significantly lower in the adrenocortical adenomas than in malignant tumors, however one benign atypical adrenocortical adenoma showed a high SUV max value. State of the art imaging techniques to characterize of adrenal tumors. In vivo proton magnetic resonance spectroscopy. MR spectroscopy is a noninvasive technique that can be used to measure the biochemical nature of living tissues. MRS has been evaluated especially for brain tumors, it has also been used to characterize prostate, breast, salivary glands, colorectal and soft tissue tumors. A recent study (11) focused on the value of spectroscopy MRI for the distinction between adrenocortical adenomas, pheochromocytomas, metastases and adrenal cortical carcinomas. Thirty-eight patients with adenomas, ten patients with pheochromocytomas, #ve patients with carcinomas, and seven patients with metastases were examined at 1.5 T. Cutoff values (for the choline/creatine ratio, the choline/lipid ratio, the lipid/créatine ratio and the ppm/créatine ratio) were found to enable adenomas and pheochromocytomas to be distinguished from carcinomas and metastases. These results were promising. However, most of the 38 adenomas included were typical, except one which could not be characterized by CT. Page 24 of 46

25 Fig. 23: MR spectroscopy performed in a 48-year-old man with right adrenal lipid-rich adenoma. References: Faria JF et al. (2007) Adrenal masses: characterization with in vivo proton MR spectroscopy--initial experience. Radiology. 245(3): Fig. 23 Diffusion-weighted MRI. Several studies have evaluated the role of diffusion weighted MRI to characterize adrenal lesions. According to a recent study (12) which included 48 patient with 49 adrenal lesions (12 malignant lesions and 37 benign lesions), In general, ADC values are not useful in differentiating adrenal lesions. However, when ADC values are applied to lesions that are indeterminate on signal intensity index, they may help in differentiating a subset of benign and malignant lesions. According to another study (13), which included 52 patients with 67 renal lesions and 28 patients with 33 adrenal lesions, ADC measurement has a potential ability to differentiate Page 25 of 46

26 benign and malignant focal renal and adrenal lesions with the guidance of conventional sequences. Dynamic contrast-enhanced MRI. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a noninvasive method of choice for the assessment of tumor microcirculation in vivo. DEC-MRI has many clinical applications especially in oncology (cerebral tumors, breast tumors, cervical carcinomas, prostate tumors, musculoskeletal tumors and liver tumors). One recent study (14) evaluated the value of DCE-MRI in the differential diagnosis of adrenal adenomas and malignant tumors, especially in cases with atypical adenomas. Sixty-four masses (48 adenomas, 16 malignant tumors) were included in the prospective study. Five dynamic series of T1-weighted spoiled gradient echo (FFE) images were obtained. At the 25th second the wash-in rates of the adenomas were signi#cantly higher than those of the malignant masses. Time-to-peak enhancement of the malignant masses was signi#cantly longer than that of the adenomas. DCE-MRI. These results were interesting especially for adrenal adenomas, which could not be characterized with chemical shift mri. Images for this section: Page 26 of 46

27 Fig. 1: Myelolipoma Spontaneous density of -94 UH Page 27 of 46

28 Fig. 2: Hematoma Spontaneous density of 56 UH. Page 28 of 46

29 Fig. 3: Enhanced CT, the density of the lesion is 18 UH : cystic mass with thin parois with no enhancement. Page 29 of 46

30 Fig. 4: TI sequence with injection : lesion in hyposignal with no enhancement. Page 30 of 46

31 Fig. 5: Left adrenal adenoma (Spontaneous density : 0 UH) Fig. 6: Evaluation of absolute and relative wash out Page 31 of 46

32 Fig. 7: Right adrenal adenoma. Spontaneous density : 41 UH Enhanced density at 1 min : 90 UH Delayed density at 10 min : 55 UH Absolute Wash Out : 71.4% (>60%) Fig. 8: Evaluation of loss of signal in chemical shift sequences Fig. 9: Left adrenal adenoma, with signal loss between in phase and out of phase sequences of more than 20%. Page 32 of 46

33 Fig. 10: Well limited mass with characteristic orange color : adrenal adenoma Page 33 of 46

34 Fig. 11: Diagnostic strategy of adrenal incidentalomas Fig. 12 Page 34 of 46

35 Fig. 13: 42-year-old woman with a Cushing syndrome. Unenhanced CT image shows a left heterogeneous adrenal mass containing calcifications, macroscopic fat and hemorrhage. Anatomopathology: adrenal cortical adenoma with hemorrhagic areas. Page 35 of 46

36 Fig. 14: 42-year-old woman with a Cushing syndrome. Axial T1 weighted image shows a left heterogeneous adrenal mass with normal signal intensity. Axial T2 weighted fat sat image shows a cystic component (area with low T1 signal intensity and high T2 signal intensity). Anatomopathology: adrenal cortical adenoma with hemorrhage. Page 36 of 46

37 Fig. 15: Adrenal cortical adenoma with large fibrino-hemorrhagic areas. Unenhanced CT image shows a left adrenal lesion with a hemorrhagic area. Fig. 16: Adrenal cortical adenoma with large fibrino-hemorrhagic areas. Macroscopy: lobulated yellow intra-adrenal tumor containing dark red focal areas. Page 37 of 46

38 Fig. 17: Adrenal cortical adenoma with large fibrino-hemorrhagic areas. Histology: proliferation of adrenal cortical cells in well vascularized interstitial tissue. No sign of malignancy. Page 38 of 46

39 Fig. 22: 53-year-old woman with Cushing syndrome. Dynamic enhanced phase CT image shows a left adrenal mass with irregular and poorly defined margins with homogeneous, and little contrast enhancement. Anatomopathology: left adrenal cortical carcinoma. Page 39 of 46

40 Fig. 20: 62-year-old man with known hepatocellular carcinoma. Enhanced phase CT image shows heterogeneous enhancement. Anatomopathology: adrenal metastases of a hepatocellular carcinoma. Page 40 of 46

41 Fig. 21: 56-year-old man with known chest carcinoma. Enhanced phase CT image shows bilateral adrenal masses, with poorly defined margins and homogeneous enhancement. Anatomopathology: adrenal metastases of a chest carcinoma. Page 41 of 46

42 Fig. 23: MR spectroscopy performed in a 48-year-old man with right adrenal lipid-rich adenoma. Page 42 of 46

43 Fig. 18: Unenhanced CT: left heterogeneous adrenal mass containing calcifications. Page 43 of 46

44 Fig. 19: Macroscopy : orange-yellow mass with maroon areas. Histology : adrenal cortical adenoma with large areas of hemorrhage. Page 44 of 46

45 Conclusion Macroscopic fat and well-defined margins seem to be important indicators of benignity for adrenal tumors that could not be identified by CT and MR examinations. PET-CT is a useful tool for uncharacterized masses: SUVmax values were significantly lower in atypical adenomas than in malignant tumors. ADC values were significantly higher in atypical adenomas than in malignant tumors. Personal Information Contact Information: Nathalie Launay Radiology Resident Cochin University Hospital midolir@yahoo.fr References 1.Boland GW. Adrenal Imaging : why, when, what and how? AJR Am J Roentgenol Feb;196(2):W Sangwaiya MJ, Boland GW, Cronin CG, Blake MA, Halpern EF, Hahn PF. Incidental adrenal lesions : accuracy of characterization with contrast-enhanced washout multidetector CT-10 minute delayed imaging protocol revisited in a large patient cohort. Radiology 2010 Aug 256 (2) Legmann P Adrenal incidentaloma: management approaches: CT-MRI. J Radiol Mar;90(3 Pt 2): Elsayes KM, Mukundan G, Narra VR, Lewis JS Jr, Shirkhoda A, Farooki A, Brown JJ. Adrenal masses: MR imaging features with pathologic correlation. Radiographics 2004 Oct;24 Suppl 1:S Page 45 of 46

46 5. Mark E. Lockhart, J. Kevin Smith, Philip J. Kenney Imaging of adrenal masses European Journal of Radiology 41 (2002) Caoili EM, Korobkin M, Francis IR, Cohan RH, Dunnick NR. Delayed enhanced CT of lipid - poor adrenal adenomas. AJR Am J Roentgenol 2000 Nov; 175(5): Johnson PT, Horton KM, Fishman EK. Adrenal Mass Imaging with Multidetector CT: Pathologic Conditions, Pearls, and Pitfalls. Radiographics Sep-Oct;29(5): Rockall AG, Babar SA, Sohaib SA, Isidori AM, Diaz-Cano S, Monson JP, Grossman AB, Reznek RH. CT and MR Imaging of the Adrenal Glands in ACTH-independent Cushing Syndrome. Radiographics Mar-Apr;24(2): Weiss LM, Medeiros LJ, Vickery AL Jr. Pathologic features of prognostic significance in adrenocortical carcinoma. Am J Surg Pathol Mar;13(3): Bharwani N, Rockall AG, Sahdev A, Gueorguiev M, Drake W, Grossman AB, Reznek RH. Adrenocortical carcinoma: the range of appearances on CT and MRI. AJR Am J Roentgenol Jun;196(6):W J.F Faria, S.M.Goldman, J.Szejnfeld, H.Meio, C.Kater, P.Kenney, M.P.Huaylias, G.Demarchi, V.V.Francisco, C.Andreoni, M.Srougi, V.Ortiz, N.Abdalla. Adrenal Masses: Characterization with in Vivo Proton MR Spectroscopy-Initial Experience. Radiology 2007 Dec;245(3): Sandrasegaran K, Patel AA, Ramaswamy R, Samuel VP, Northcutt BG, Frank MS, Francis IR. Characterization of adrenal masses with diffusion-weighted imaging. JR Am J Roentgenol. Jul 2011;197(1): Kilickesmez O, Inci E, Atilla S, Tasdelen N, Yetimo#lu B, Yencilek F, Gurmen N. Diffusion-weighted imaging of the renal and adrenal lesions. J Comput Assist Tomogr. Nov-Dec 2009;33(6): Inan N, Arslan A, Akansel G, Anik Y, Balci NC, Demirci A. Dynamic contrast enhanced MRI in the differential diagnosis of adrenal adenomas and malignant adrenal masses EJR 65 (2008) Page 46 of 46