High temporal resolution 3D gadolinium-enhanced dynamic MR imaging of renal tumors with pharmacokinetic modeling: preliminary observations.

Overview

PURPOSE: To assess dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) tracer pharmacokinetic parameters obtained with Generalized Kinetic Model (GKM) and extended Shutter Speed Model (SSM2) in renal tumors stratified by histologic subtypes. MATERIALS AND METHODS: In all, 24 patients with renal tumors were imaged at 1.5 T utilizing DCE-MRI with high temporal resolution (1.2 sec/temporal frame) prior to surgery. Tracer kinetic analysis was performed for the entire tumor using individualized aortic input function. GKM and SSM2 were employed to generate transfer constant (K(trans)), plasma volume, and interstitial volume. These parameters, and ΔK(trans) (K(trans)SSM2 - K(trans)GKM) were compared between tumors stratified by histologic subtype. RESULTS: There were 25 renal tumors: 15 clear cell, 4 papillary, 3 chromophobe, and 3 oncocytoma/oncocytic subtype. K(trans)GKM was significantly higher in chromophobe compared to other subtypes (P < 0.01). Using K(trans)GKM > 1.0 min(-1), chromophobe were diagnosed with 100% sensitivity and 90.9% specificity. K(trans)SSM2 was higher than K(trans)GKM for all renal tumors except for all chromophobe and two clear cell subtype. Using K(trans)GKM > 1.0 min(-1) and Δ K(trans) < 0, chromophobe could be discriminated from other lesions with 100% accuracy. CONCLUSION: K(trans) obtained with GKM and SSM2 analysis can potentially discriminate chromophobe from other renal lesions with high accuracy.