Df. Dubois et al., INTRAOBSERVER AND INTEROBSERVER VARIABILITY OF MR IMAGING-DERIVED ANDCT-DERIVED PROSTATE VOLUMES AFTER TRANSPERINEAL INTERSTITIAL PERMANENT PROSTATE BRACHYTHERAPY, Radiology, 207(3), 1998, pp. 785-789
PURPOSE: To evaluate the relative accuracy and precision of magnetic r
esonance (MR) imaging and computed tomography (CT) in the assessment o
f postimplantation prostate volume by determining intraobserver, inter
observer, and intermodality variations. MATERIALS AND METHODS: CT and
MR images of 41 consecutive patients, after transperineal interstitial
permanent prostate brachytherapy, were evaluated by two physicians to
determine interobserver and intermodality variability in prostate vol
ume measurements. Repeat evaluation in five randomly selected patients
was used to determine intraobserver variability. RESULTS: Observer 1
versus 2 CT-determined mean prostate volume difference was statistical
ly significant (-8.5 cm(3)+/-9.7[standard deviation],P <.001);observer
1 versus 2 MR-determined mean prostate volume difference was not sign
ificant (1.9cm(3)+/-11.7,P = .492). CT intraobserver range of dimensio
nal errors was 3.5 and 11.4 times that of MR imaging. Observer 1 CT an
d MR volumes were significantly different (P = .001);observer 2 CT and
MR volumes were not significantly different (P = .079). CONCLUSIONS:
With both CT and MR imaging, variation is less when evaluations are co
nducted by one observer. Variation in one observer may be further redu
ced by using MR imaging in place of CT.