Transrectal ultrasonography (TRUS) has been used as diagnostic tool for prostate cancer. However, its clinical usefulness is questionable because it is a subjective method that results in interobserver variation. We studied the usefulness of time intensity curve (TIC) and color-commune image (CCI) created by ultrasound contrast agent, Perfulbutane-enhanced TRUS (PEU), for objective diagnosis of prostate cancer.
Of the patients who were histologically diagnosed with prostate cancer by the 14-region systematic biopsy and had PEU performed before biopsy, we selected 37 cases who had 4 or more cancer positive regions in one side (C side, CS) and 0 or 1 in the other side (NC side, NCS) in this study. For PEU the SSA-790A unit, fitted with an endorectal endfire probe (PVT-661VT), was used. The software used for TIC was TIC®, and for CCI was the Parametric imaging®. All instruments and software used for PEU were from Toshiba Medical Systems, Tokyo. The Perfulbutane was from Daiichi-Sankyo Co., Tokyo. We recorded ultrasound images for 60 seconds after injection of Perfulbutane. For TIC, we placed one region of interest (ROI) on one each of the CS and NCS. The time from Perfulbutane injection to the contrast enhancement peak (Tp), the intensity change from the baseline to peak (Ip) and Ip/Tp of the CS and NCS were measured from TIC and compared statistically using the Mann–Whitney U-test. For CCI the Parametric imaging® software was used to create color image of the time-course change of vascular enhancement by Perfulbutane inside and outside the prostate by changing the color every 2 seconds for initial 12 seconds, and thereafter is one color.
The CS had significantly shorter Tp (13.6 and 15.3 seconds, p = 0.0428), and higher Ip (29.2 and 17.4 dB, p < 0.0001) and Ip/TpS (2.4 and 1.3, p < 0.0001) compared to the NCS. The CCI successfully depicted the time-course change of vascular enhancement by Perfulbutane inside and outside the prostate, and that was well-correlated with the TIC findings.
TIC and CCI created by PEU could be useful objective diagnostic tools for prostate cancer.
Clinical trial identification
G. Kimura: Astellas, Takeda, Pfizer, Bayer, Novartis, GlaxoSmithKline, Ono Pharmaceutical. All other authors have declared no conflicts of interest.