Multiparametric MRI Examination and Image Analysis
Multiparametric prostate MRI was performed using a 3.0-T MR unit (Verio; Siemens Medical Solutions, Erlagen, Germany) with a 16-channel pelvic phased array coil. Imaging sequences comprised thin-section turbo spin echo T2-weighted (TSE) images (number of slices, 20; slice thickness, 3 mm with no intersection gap; TR/TE, 5800/100 ms; number of signals acquired, 2; and resolution, 0.8x0.8 mm) in the transverse, sagittal and coronal planes. Diffusion-weighted images were obtained using multiple b values (b-factor, 50/500/1000/1500 s/mm2; number of slices, 20; slice thickness, 3 mm; TR/TE, 3900/75; and resolution, 1.4 mmx1.4 mm) in the transverse plane and apparent diffusion coefficient (ADC) maps were constructed from the b50, b100, b1000 and b1500 images by utilizing SyngoVia WorkStation software. Dynamic contrast-enhanced (DCE)-MRI sequences (T1 high-resolution isotropic volume with fat suppression) obtained after the administration of a gadolinium injection (slice thickness, 3 mm; intersection gap, none; TR/TE, 5.08/1.77; resolution, 1.4 mmx1.4 mm, contrast agent injection started 24 seconds after first acquisition; temporal resolution, 8 seconds; total DCE time, 200 seconds; and number of dynamic time points, 25). We stratified the study cohort into two groups using a tumor diameter of 1 cm. Group A consisted of patients with normal MRI findings or a suspicious tumor lesion of <1 cm in diameter, and Group B comprised those with a tumor diameter of > 1 cm (Figure 1).