title: Proton-density fat fraction measurement: A viable quantitative biomarker for differentiating adrenal adenomas from nonadenomas.
abstract: OBJECTIVE
  This study aims to compare the accuracy of proton-density fat fraction (PDFF) measurements with chemical shift magnetic resonance imaging (CSI) for quantifying the fat content of adrenal nodules and for differentiating adenomas from nonadenomas.
  
  
  METHODS
  Oil-saline phantom measurements was performed to compare the correlation between PDFF and CSI in detecting and quantifying fat content. 43 consecutive patients who had known adrenal nodules were imaged on a 3.0-T MR scanner. PDFF was measured, and the signal intensity (SI) index (SII), SI adrenal-to-liver ratio (ALR) and SI adrenal-to-spleen ratio (ASR) of the adrenal nodules were calculated.
  
  
  RESULTS
  In the phantom study, PDFF ranged from 12.6% to 99.1% and the SII was between 0.72 and 1.23. There was good correlation between these two methods (R square=0.972, p<0.0001). The PDFF of adrenal adenoma was significantly increased compared with that of nonadenoma (p<0.001). PDFF was an effective tool for distinguishing adenoma from nonadenoma, with an area under the curve (AUC) of 0.98. In comparing SII, ALR and ASR the AUC was 0.94, 0.95 and 0.93, respectively. No significant difference was noted between these two methods (p>0.05).
  
  
  CONCLUSIONS
  PDFF measurements provide an accurate estimation of fat content in discriminating adenomas from nonadenomas compared with CSI, avoiding complicated data calculations and offering a simpler technique using 3T.
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Meng
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Yaqi
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Hu
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Tang
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Daoyu
authors.initials: D
authors.lastname: Hu
authors.affiliation: Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China. Electronic address: zhenli@hust.edu.cn.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Li
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, the Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors.forename: Ihab R
authors.initials: IR
authors.lastname: Kamel
mesh_terms: D000236:Adenoma / Q000473:pathology*; D000273:Adipose Tissue / Q000473:pathology; D000306:Adrenal Cortex Neoplasms / Q000473:pathology; D000310:Adrenal Gland Neoplasms / Q000473:pathology*; D018246:Adrenocortical Adenoma / Q000473:pathology; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D014408:Biomarkers, Tumor / Q000378:metabolism; D005260:Female; D006801:Humans; D008107:Liver Diseases / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D011522:Protons
chemical_list: D014408:Biomarkers, Tumor; D011522:Protons
keywords: Adenoma; Chemical shift imaging; Magnetic resonance imaging; Metastasis; Pheochromocytoma