title: Characterization of adrenal lesions using chemical shift MRI: comparison between 1.5 Tesla and two echo time pair selection at 3.0 Tesla MRI.
abstract: OBJECTIVE
  To compare chemical shift MRI obtained at 1.5 Tesla (T) and two pairs of echo time (TE) in-phase and opposed-phase 3.0T MRI to assess their usefulness for the differentiation between adrenal adenomas and non-adenomas.
  
  
  METHODS
  We evaluated 91 adrenal masses (75 adenomas, 16 non-adenomas) in 85 patients. The MR imaging parameters were: T1-dual-gradient-echo(GRE) [echo times (TEs) = 1.1/2.3 ms (first-echo-pair) or 3.5/4.6 ms (second-echo-pair)] at 3.0T, and T1-dual-GRE (TEs = 2.4/4.8 ms) at 1.5T. Scans were quantitatively assessed for the signal intensity (SI) index, calculated as [(SIin-phase-SIopposed-phase)/(SIin-phase)] × 100(%). To test for differences between adenomas and non-adenomas, we performed quantitative analysis and analysis of variance.
  
  
  RESULTS
  For all images, the SI index differed significantly between adenomas and non-adenomas. The sensitivity /specificity of SI index at the first-echo-pair of 3.0T was 100%/ 100%, that of 95.6%/ 100% at the second-echo-pair of 3.0T, and 91.7%/ 88.9% at 1.5T, respectively. At intra-individual comparisons, the SI indices obtained with the second-echo-pair at 3.0T were significantly lower than on the first-echo-pair at 3.0T and 1.5T.
  
  
  CONCLUSIONS
  Chemical shift MRI at 3.0T provides more accurate differentiation between adenomas and non-adenomas than at 1.5T. The SI index of the first-echo-pair at 3.0T is the most reliable evaluation method for differentiating adrenal adenomas from non-adenomas.
authors: Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan.
authors: Shinichi
authors: S
authors: Nakamura
authors: Tomohiro
authors: T
authors: Namimoto
authors: Kosuke
authors: K
authors: Morita
authors: Daisuke
authors: D
authors: Utsunomiya
authors: Seitaro
authors: S
authors: Oda
authors: Takeshi
authors: T
authors: Nakaura
authors: Toshinori
authors: T
authors: Hirai
authors: Yasuyuki
authors: Y
authors: Yamashita
mesh_terms: D000236:Adenoma / Q000175:diagnosis / Q000473:pathology*; D000293:Adolescent; D000310:Adrenal Gland Neoplasms / Q000175:diagnosis / Q000473:pathology*; D000311:Adrenal Glands / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome