Objectives: To determine the accuracy of contrast-enhanced transrectal ultrasonography for tumor size measurements of hypoechoic prostate cancer foci located in the peripheral zone.
Methods: A total of 55 men scheduled for radical prostatectomy, with biopsy-proven cancer in hypoechoic foci located in the peripheral zone, were consecutively enrolled in the present prospective study. Each patient underwent grayscale ultrasound and contrast-enhanced transrectal ultrasonography of the prostate according to a standardized protocol. The maximum tumor diameter on grayscale imaging and contrast-enhanced transrectal ultrasonography was compared with that determined using histopathology.
Results: A mean underestimation was documented to be approximately 3.9 mm and 0.6 mm for grayscale and contrast-enhanced transrectal ultrasonography imaging, respectively. Grayscale and contrast-enhanced transrectal ultrasonography imaging underestimated measurements by 76.67% (46 of 60) and 48.33% (29 of 60), whereas overestimated measurements were 20% (12 of 60) and 26.67% (16 of 60), respectively. A strong correlation was observed between contrast-enhanced transrectal ultrasonography and histopathological measurements (r = 0.91, P < 0.0001). A weak linear correlation was found between grayscale and histopathological measurements (r = 0.59, P < 0.0001). Bland-Altman analysis results were in complete accordance with correlation analysis results. For cases with maximum histopathological tumor diameters ≤10 mm and >10 mm, 40% (6 of 15) and 86.67% (39 of 45) were index tumors, respectively (P < 0.0001).
Conclusions: Contrast-enhanced transrectal ultrasonography is significantly more accurate than conventional grayscale imaging for measuring prostate tumor size, especially for tumors with a diameter >10 mm, and it might have a role in preoperative assessment of prostatic index tumor sizes.
Keywords: contrast-enhanced ultrasonography; grayscale; prostate cancer; radical prostatectomy.
© 2013 The Japanese Urological Association.