Volume and landmark analysis: comparison of MRI measurements obtained with an endorectal coil and with a phased-array coil

• Measurements of prostate geometry are compared on MRI with two coil arrangements.
• Prostate volume did not differ significantly between the two coil arrangements.
• Distances differed significantly between the two coil arrangements.

AimTo compare prostate volumes and distances between anatomical landmarks on MRI images obtained with a phased-array coil (PAC) only and with a PAC and an endorectal coil (ERC).Materials and methodsInformed consent was waived for this Health Insurance Portability and Accountability Act-compliant study. Fifty-nine men underwent PAC-MRI and ERC-MRI at 1.5 (n = 3) or 3 T (n = 56). On MRI images, two radiologists independently measured prostate volume and distances between the anterior rectal wall (ARW) and symphysis pubis at the level of the verumontanum; ARW and symphysis pubis at the level of the mid-symphysis pubis; and bladder neck and mid-symphysis pubis. Differences between measurements from PAC-MRI and ERC-MRI were assessed with the Wilcoxon RANK SUM test. Inter-reader agreement was assessed using the concordance correlation coefficient (CCC).ResultsDifferences in prostate volume between PAC-MRI and ERC-MRI [median: −0.75 mm3 (p = 0.10) and median: −0.84 mm3 (p = 0.06) for readers 1 and 2, respectively] were not significant. For readers 1 and 2, median differences between distances were as follows: −10.20 and −12.75 mm, respectively, ARW to symphysis pubis at the level of the verumontanum; −6.60 and −6.08 mm, respectively, ARW to symphysis pubis at the level of the mid-symphysis pubis; −3 and −3 mm respectively, bladder neck to mid-symphysis pubis. All differences in distance were significant for both readers (p ≤ 0.0005). Distances were larger on PAC-MRI (p ≤ 0.0005). Inter-reader agreement regarding prostate volume was almost perfect on PAC-MRI (CCC: 0.99; 95% CI: 0.98–1.00) and ERC-MRI (CCC: 0.99; 95% CI: 0.99–1.00); inter-reader agreement for distance measurements varied (CCCs: 0.54–0.86).ConclusionMeasurements of distances between anatomical landmarks differed significantly between ERC-MRI and PAC-MRI, although prostate volume measurements did not.