title: In-phase signal intensity loss in solid renal masses on dual-echo gradient-echo MRI: association with malignancy and pathologic classification.
abstract: OBJECTIVE
  The purposes of this study were to determine the prevalence of in-phase signal intensity loss on dual-echo gradient-echo MRI in solid renal masses using visual and quantitative techniques and to test for any association between in-phase signal intensity loss and pathologic classification.
  
  
  METHODS
  The renal MRI studies of 177 patients (192 solid masses consisting of 166 renal cell carcinomas [RCCs], four malignant non-RCCs, and 22 benign tumors) were qualitatively reviewed by two blinded readers for visual evidence of relative in-phase signal intensity loss. For lesions without visual evidence, whole-lesion ROIs were used to attempt quantification of subtle signal intensity loss between opposed- and in-phase images (signal intensity loss index).
  
  
  RESULTS
  Visual in-phase signal intensity loss was noted in 18% of clear cell RCC, 42% of papillary RCC, and no benign lesions. There was significant correlation between malignancy and visual signal intensity loss (Fisher exact test, p = 0.0092). Visual signal intensity loss was predictive of papillary RCC over clear cell RCC (odds ratio, 5.79; p = 0.0002) in logistic regression analysis of all RCCs, controlling for size. Quantitative assessment of remaining lesions provided no additional diagnostic benefit.
  
  
  CONCLUSIONS
  Visible in-phase signal intensity loss is relatively common within solid renal masses and was associated with RCC and particularly papillary RCC (among all RCCs) in our population. Quantitative analysis in lesions without visible signal intensity loss was not predictive of RCC. Further work should be performed to validate the usefulness of this additional imaging parameter to help characterize renal masses and to determine the impact of this finding on imaging techniques potentially sensitive to susceptibility effects.
authors.affiliation: 1 Department of Radiology, Wake Forest University School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157.
authors.forename: David D
authors.initials: DD
authors.lastname: Childs
authors.forename: M Jennings
authors.initials: MJ
authors.lastname: Clingan
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Zagoria
authors.forename: Joseph
authors.initials: J
authors.lastname: Sirintrapun
authors.forename: Kaan
authors.initials: K
authors.lastname: Tangtiang
authors.forename: Andrea
authors.initials: A
authors.lastname: Anderson
authors.forename: John R
authors.initials: JR
authors.lastname: Leyendecker
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D016477:Artifacts; D002292:Carcinoma, Renal Cell / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007680:Kidney Neoplasms / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio; D016037:Single-Blind Method; D055815:Young Adult
keywords: dual-echo gradient-echo MRI; hemosiderin; renal MRI; renal mass