T1-hyperintense renal lesions: can high signal predict lack of enhancement?

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. Materials and 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