title: Quantitative Versus Qualitative Methods in Evaluation of T2 Signal Intensity to Improve Accuracy in Diagnosis of Pheochromocytoma.
abstract: OBJECTIVE
  The purpose of this study was to assess T2 signal intensity (SI) of adrenal pheochromocytoma at 1.5 T using the rapid acquisitions with relaxation enhancement (RARE) sequence. We also sought to determine whether quantitative parameters can distinguish pheochromocytoma from other adrenal lesions with better accuracy than conventional qualitative methods.
  
  
  METHODS
  MRI examinations of 74 patients (26 with pheochromocytoma, 25 with lipid-poor adenomas, 18 with malignant adrenal lesions, and five with adrenal cysts) were retrospectively reviewed. MRI sequences included single-shot fast spin-echo (n = 38) and fast-recovery fast spin-echo (n = 36) acquisitions. T2 SI of lesions was qualitatively compared with CSF. Quantitative evaluation included applying ROI measurements and calculating SI ratio of each mass to liver, spleen, paraspinal muscle, and CSF. Twoway ANOVA compared SI ratios between different adrenal lesions and between two pulse sequences. ROC analysis determined the optimal threshold SI ratio for distinguishing pheochromocytomas from other adrenal lesions.
  
  
  RESULTS
  Sixty-nine percent of pheochromocytomas displayed isointensity to CSF (p < 0.005), resulting in 81% specificity and 69% sensitivity for differentiation of pheochromocytomas from lipid-poor adenomas and malignant lesions. Adrenal-to-muscle SI ratio was the strongest discriminator for differentiation of pheochromocytomas from other lesions. A threshold of at least 3.95 yielded 88% specificity and 81% sensitivity for distinguishing pheochromocytomas from lipid-poor adenomas and malignant adrenal lesions.
  
  
  CONCLUSIONS
  Quantitative normalization of T2 SI with reference to muscle improves the sensitivity and specificity profile for differentiation of pheochromocytoma compared with qualitative assessment alone. At 1.5 T field strength, an adrenal-to-muscle SI ratio of at least 3.95 is recommended.
authors.affiliation: 1 Department of Radiology, Division of Abdominal Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA.
authors.forename: Amir A
authors.initials: AA
authors.lastname: Borhani
authors.affiliation: 2 Department of Radiology, Division of Abdominal Imaging, Wake Forest University School of Medicine, One Medical Center Blvd, Winston-Salem, NC 27157.
authors.forename: Keyanoosh
authors.initials: K
authors.lastname: Hosseinzadeh
mesh_terms: D000293:Adolescent; D000310:Adrenal Gland Neoplasms / Q000175:diagnosis* / Q000473:pathology; D000328:Adult; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010673:Pheochromocytoma / Q000175:diagnosis* / Q000473:pathology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
keywords: adrenal MRI; adrenal lesion; pheochromocytoma