title: T1-hyperintense renal lesions: can high signal predict lack of enhancement?
abstract: OBJECTIVE
  To establish highly specific criteria for predicting non-enhancement in T1-hyperintense non-fat-containing (T1-high) renal lesions using unenhanced fat-suppressed T1-weighted (T1-FS) images.
  
  
  METHODS
  This IRB-approved, HIPAA-compliant, retrospective study included T1-high renal lesions found between 7/1/2012 and 7/1/2014. The largest lesion diameter and heterogeneity, mean signal intensity of lesion, and adjacent renal cortex were recorded from T1-FS images. The presence/absence of lesion enhancement was determined from subtraction images. T1 signal ratio (T1-SR) was calculated as (mean SI of lesion)/(mean SI of cortex). Logistic regression with binary outcome of the presence or absence of lesion enhancement was performed. Cut-off T1-SR to maximize specificity was established from receiver operator curve analysis.
  
  
  RESULTS
  There were 101 patients (58 [57.4%] male) with non-enhancing lesions and 80 patients (51 [63.8%] male) with enhancing lesions, mean ages 64.0 ± 13.3 and 62.1 ± 13.8 years, respectively. Median sizes were 11 mm (IQR 8-16) and 20.5 mm (IQR 15-29) for non-enhancing and enhancing lesions, respectively (p < 0.0001). 19/101 (18.8%) of non-enhancing and 56/80 (70.0%) of enhancing lesions were heterogeneous (p < 0.0001). T1-SR was 1.77 ± 0.6 and 1.25 ± 0.42 for non-enhancing and enhancing lesions, respectively (p < 0.0001). For each increase of 0.5 in T1-SR, odds ratio for non-enhancement was 3.3 (95% CI 1.85-5.79), adjusted for lesion size and heterogeneity. T1-SR alone had area under the curve of 0.88 (95% CI 0.78-10.89) for non-enhancement. T1-SR ≥ 2.15 had positive likelihood ratio of 9.5 for non-enhancement.
  
  
  CONCLUSIONS
  Signal ratio of lesion to cortex ≥ 2.15 on unenhanced T1-weighted images is a highly specific predictor for non-enhancement.
authors.affiliation: Department of Radiology, Montefiore Medical Center, 111 E. 210th St., Bronx, NY, 10467, USA. jle@montefiore.org.
authors.forename: Jenna
authors.initials: J
authors.lastname: Le
authors.affiliation: Department of Radiology, Montefiore Medical Center, 111 E. 210th St., Bronx, NY, 10467, USA.
authors.forename: Milana
authors.initials: M
authors.lastname: Flusberg
authors.affiliation: Department of Radiology, Montefiore Medical Center, 111 E. 210th St., Bronx, NY, 10467, USA.
authors.forename: Alla M
authors.initials: AM
authors.lastname: Rozenblit
authors.affiliation: Department of Radiology, Montefiore Medical Center, 111 E. 210th St., Bronx, NY, 10467, USA.
authors.forename: Victoria
authors.initials: V
authors.lastname: Chernyak
mesh_terms: D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D007668:Kidney / Q000473:pathology; D007680:Kidney Neoplasms / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
chemical_list: D003287:Contrast Media
keywords: Incidentalomas; Renal cell carcinoma; Renal cysts; Renal masses