Objective: The aim of this study was to assess the effect of temporal resolution on semiquantitative and pharmacokinetic parameters from dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and their diagnostic accuracy regarding the detection of potentially malignant prostate lesions.
Materials and methods: Sixty consecutive male patients (age, 64.5 ± 7.0 years) with clinically suspected prostate cancer were included. All patients underwent multiparametric MRI of the prostate (T2-weighted, diffusion-weighted imaging, and DCE-MRI) on a 3 T MRI scanner. Patients were divided into 2 groups depending on Prostate Imaging Reporting and Data System (PI-RADS) score of the detected lesions (group A: PI-RADS score ≤3, n = 30; group B: PI-RADS score >3, n = 30). In all patients, DCE-MRI was performed using a CAIPIRINHA-Dixon-TWIST Volume-Interpolated Breath-Hold Examination sequence (spatial resolution, 3 × 1.2 × 1.2 mm; temporal resolution, 5 seconds; total sampling duration, 4:10 minutes [250 seconds]) with body weight-adapted administration of contrast agent (gadobutrol, Gadovist; Bayer Healthcare, Berlin, Germany). Six DCE-MRI series with different temporal resolutions ranging from 5 to 30 seconds per time point were retrospectively generated from the original data sets. Semiquantitative parameters (ie, wash-in, wash-out, and time-to-peak [TTP]) as well as pharmacokinetic parameters (ie, Ktrans, Kep, and ve) were calculated for the different temporal resolutions. Both lesion groups and all 6 DCE-MRI series were compared regarding semiquantitative and pharmacokinetic parameters. Diagnostic accuracy for the detection of potentially malignant lesions was calculated for all 6 series using ROC analysis.
Results: A significant effect of temporal resolution was found on wash-in (P < 0.001). Series with temporal resolution lower than 10 s/time point showed significantly lower wash-in values with more pronounced effects in group B compared with group A. For 30-second series, the differences between both groups diminished reaching insignificant levels (P = 0.052), resulting in a significant decrease of the diagnostic accuracy of wash-in (area under the curve, 0.609; 95% confidence interval, 0.451-0.766; P < 0.015). No significant effects were detected on wash-out. For TTP, a significant effect of temporal resolution was detected (P < 0.001) with significantly increasing TTP levels for all down-sampled series compared with the original 5-second series. These effects did not impact the diagnostic accuracy of TTP. No significant effects of temporal resolution were detected on pharmacokinetic parameters (P < 0.112).
Conclusions: In DCE-MRI of the prostate, temporal resolution affects the diagnostic performance of semiquantitative parameters. For a sufficient detection of malignant prostate lesions on DCE-MRI, a temporal resolution of at least 10 s/time point or higher is recommended.