title: Diagnostic utility of diffusion-weighted MR imaging and apparent diffusion coefficient value for the diagnosis of adrenal tumors.
abstract: OBJECTIVE
  To determine the utility of diffusion-weighted MR imaging (DWI) for the diagnosis of adrenal tumors.
  
  
  METHODS
  Forty-two patients (24 men and 18 women; age, 61.5 +/- 12.7 years old; range, 34-86 years) with 43 adrenal tumors (11 functioning cortical adenomas, 20 nonfunctioning cortical adenomas, 7 metastatic tumors, and 5 pheochromocytomas) were retrospectively investigated. DWIs were obtained by single-shot spin-echo type echo-planar imaging sequence (1.5 Tesla [T]; TR = 8000 ms, TE = 72, b-factor = 0 and 1000 s/mm(2)), and apparent diffusion coefficient (ADC) value was calculated. Chemical shift images were obtained by gradient echo sequence (TR = 161, TE = 2.38 [out-of-phase, OP] and 4.76 [in-phase, IP], FA = 60), and the signal intensity index (SII; [IP-OP]/IP *100%) was calculated.
  
  
  RESULTS
  There was no difference in ADC values between adenomas (1.09 +/- 0.29*10(-3) mm(2)/s; range, 0.52-1.64) and metastatic tumors (0.85 +/- 0.26*10(-3); 0.51-1.23; p = 0.14). Pheochromocytomas showed the higher mean ADC value (1.59 +/- 0.34*10(-3); 1.04-1.96) compared with those of adenomas or metastatic tumors (P < 0.05 and P < 0.005, respectively). The mean SII of adenomas (62.1 +/- 17.9%; 14.5-88.4) was significantly higher than those of pheochromocytomas (4.0 +/- 10.0%; -19.6-3.3; P < 0.005) or metastatic tumors (-1.5 +/- 11.7%; -18.3-8.2; P < 0.01). There was no correlation between ADC values and SII.
  
  
  CONCLUSIONS
  Although pheochromocytomas showed higher ADC values, we did not find that ADC value had diagnostic utility for differentiating adenomas and metastatic tumors.
authors.affiliation: Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Hospital, Gunma, Japan. tyoshito@showa.gunma-u.ac.jp
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Tsushima
authors.forename: Ayako
authors.initials: A
authors.lastname: Takahashi-Taketomi
authors.forename: Keigo
authors.initials: K
authors.lastname: Endo
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity