Tumorsize dependent detection rate of endorectal MRI of prostate cancer—A histopathologic correlation with whole-mount sections in 70 patients with prostate cancer

PurposeTo evaluate the value of T2w endorectal MRI (eMRI) for correct detection of tumor foci within the prostate regarding tumor size.Materials and Methods70 patients with histologically proven prostate cancer were examined with T2w eMRI before radical prostatectomy at a 1.5 T scanner. For evaluation of eMRI, two radiologists evaluated each tumor focus within the gland. After radical prostatectomy, the prostates were prepared as whole-mount sections, according to transversal T2w eMRI. For each slice, tumor surroundings were marked and compared with eMRI. Based on whole-mount section, 315 slices were evaluated and 533 tumor lesions were documented.ResultsBased on the T2w eMRI, 213 tumor lesions were described. In 137/213, histology could prove these lesions. EMRI was able to visualize 0/56 lesions with a maximum size of <0.3 cm (detection rate 0%), between 0.3 and 0.5 cm 4/116 (3%), between 1 and 0.5 cm 22/169 (13%), between 2 and 1 cm 61/136 (45%) and for >2 cm 50/56 (89%). False positive eMRI findings were: <0.3 cm n = 0, 0.5–0.3 cm n = 12, 0.5–1 cm n = 34, 1–2 cm n = 28 and >2 cm n = 2.ConclusionT2w eMRI cannot exclude prostate cancer with lesions smaller 10 mm and 0.4 cm3 respectively. The detection rate for lesions more than 20 mm (1.6 cm3) is to be considered as high.