Accuracy of prostate measurements on MRI with and without an endorectal coil

PurposeTo assess accuracy of prostate measurements with and without endorectal coil (ERC).Materials and methodsAnteroposterior (AP), transverse (TX) and craniocaudal (CC) measurements were recorded from 49 prostate magnetic resonance images (MRIs) done both with and without ERC. Prostate weight was calculated as follows: AP*TX*CC*π/6. Prostate dimensions and weight were obtained from radical prostatectomy pathology report.ResultsAfter ERC placement, AP decreased by 0.71 cm [95% confidence interval (CI) 0.80–0.61], TX and CC increased by 0.26 cm (95% CI 0.18–0.33) and 0.25 cm (95% CI 0.16–0.35), respectively. Agreement between weight on pathology and MR was excellent: intraclass correlation coefficient (ICC) without ERC=0.96, ICC with ERC=0.90.ConclusionAlthough ERC distorts measurements and despite a tendency to underestimate the prostate weight, absolute agreement between prostate weight on pathology and MRI is excellent, both with and without ERC.