Prostate Volume Measurement by TRUS Using Heights Obtained by Transaxial and Midsagittal Scanning: Comparison with Specimen Volume Following Radical Prostatectomy

OBJECTIVE The purpose of this study was to determine, when measuring prostate volume by TRUS, whether height is more accurately determined by transaxial or midsagittal scanning. MATERIALS AND METHODS Sixteen patients who between March 1995 and March 1998 underwent both preoperative TRUS and radical prostatectomy for prostate cancer were included in this study. Using prolate ellipse volume calculation (height x length x width x pi/6), TRUS prostate volume was determined, and was compared with the measured volume of the specimen. RESULTS Prostate volume measured by TRUS, regardless of whether height was determined transaxially or midsagittally, correlated closely with real specimen volume. When height was measured in one of these planes, a paired t test revealed no significant difference between TRUS prostate volume and real specimen volume (p =.411 and p =.740, respectively), nor were there significant differences between the findings of transaxial and midsagittal scanning (p =.570). A paired sample test, however, indicated that TRUS prostate volumes determined transaxially showed a higher correlation coefficient (0.833) and a lower standard deviation (9.04) than those determined midsagittally (0.714 and 11.48, respectively). CONCLUSION Prostate volume measured by TRUS closely correlates with real prostate volume. Furthermore, we suggest that when measuring prostate volume in this way, height is more accurately determined by transaxial than by midsagittal scanning.