Dynamic contrast-enhanced MRI of the prostate: An intraindividual assessment of the effect of temporal resolution on qualitative detection and quantitative analysis of histopathologically proven prostate cancer.

ABSTRACT

PURPOSE: To assess the effects of temporal resolution (RT ) in dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) on qualitative tumor detection and quantitative pharmacokinetic parameters in prostate cancer. MATERIALS AND METHODS: This retrospective Institutional Review Board (IRB)-approved study included 58 men (64 ± 7 years). They underwent 3T prostate MRI showing dominant peripheral zone (PZ) tumors (24 with Gleason ≥ 4 + 3), prior to prostatectomy. Continuously acquired DCE utilizing GRASP (Golden-angle RAdial Sparse Parallel) was retrospectively reconstructed at RT of 1.4 sec, 3.7 sec, 6.0 sec, 9.7 sec, and 14.9 sec. A reader placed volumes-of-interest on dominant tumors and benign PZ, generating quantitative pharmacokinetic parameters (ktrans , ve ) at each RT . Two blinded readers assessed each RT for lesion presence, location, conspicuity, and reader confidence on a 5-point scale. Data were assessed by mixed-model analysis of variance (ANOVA), generalized estimating equation (GEE), and receiver operating characteristic (ROC) analysis. RESULTS: RT did not affect sensitivity (R1all 69.0%-72.4%, all Padj = 1.000; R1GS≥4 + 3 83.3-91.7%, all Padj = 1.000; R2all 60.3-69.0%, all Padj = 1.000; R2GS≥4 + 3 58.3%-79.2%, all Padj = 1.000). R1 reported greater conspicuity of GS ≥ 4 + 3 tumors at RT of 1.4 sec vs. 14.9 sec (4.29 ± 1.23 vs. 3.46 ± 1.44; Padj = 0.029). No other tumor conspicuity pairwise comparison reached significance (R1all 2.98-3.43, all Padj ≥ 0.205; R2all 2.57-3.19, all Padj ≥ 0.059; R1GS≥4 + 3 3.46-4.29, all other Padj ≥ 0.156; R2GS≥4 + 3 2.92-3.71, all Padj ≥ 0.439). There was no effect of RT on reader confidence (R1all 3.17-3.34, all Padj = 1.000; R2all 2.83-3.19, all Padj ≥ 0.801; R1GS≥4 + 3 3.79-4.21, all Padj = 1.000; R2GS≥4 + 3 3.13-3.79, all Padj = 1.000). ktrans and ve of tumor and benign tissue did not differ across RT (all adjusted P values [Padj ] = 1.000). RT did not significantly affect area under the curve (AUC) of Ktrans or ve for differentiating tumor from benign (all Padj = 1.000). CONCLUSION: Current PI-RADS recommendations for RT of 10 seconds may be sufficient, with further reduction to the stated PI-RADS preference of RT ≤ 7 seconds offering no benefit in tumor detection or quantitative analysis. LEVEL OF EVIDENCE 3 J. MAGN. RESON. IMAGING 2017;451464-1475.