Use of maximum slope images generated from dynamic contrast-enhanced MRI to detect locally recurrent prostate carcinoma after prostatectomy: A practical approach

OBJECTIVE. The purpose of this article is to present the value of high-temporal-resolution and high-spatial-resolution dynamic contrast-enhanced MRI (DCE-MRI) combined with the postprocessed slope images generated from the fastest rate of enhancement of each voxel for detecting local recurrence of prostate carcinoma after radical prostatectomy. Met hods and Materi als. Of 125 patients, 47 patients with and without local recurrence confirmed by biopsy or clinical follow-up were identified. All patients underwent DCE-MRI with a spatial resolution of 3 mm and mean temporal resolution of 11.3 seconds (range, 8.4-14.0 seconds). RESULTS. In patients with local recurrence, the mean (± SD) prostate-specific antigen level and tumor size were 1.9 ± 1.8 mg/dL and 10.8 ± 5.7 mm, respectively, at the time of MRI. Thirty-six of 37 patients (97%) with biopsy or clinically confirmed local recurrence had positive MRI findings. Eight of 10 patients (80%) with negative recurrence had negative MRI findings. Of the 36 patients, 16 (44%) had time-intensity curves of rapid increase-rapid washout and 18 (50%) had rapid increase-plateau or slow washout. The recurrent tumor reached the peak enhancement within one phase following the peak enhancement of the common femoral artery. In patients with a negative MRI result, the mean PSA level was 0.2 ± 0.1 mg/dL. Conclusio n. DCE-MRI using high temporal and spatial resolution is highly accurate in detecting subcentimeter local recurrences within the postprostatectomy bed. Combined with visual inspection of original source images (using the common femoral artery as a reference), the slope image is a simple and practical way of identifying locally recurrent prostate carcinoma.