Factors influencing the degree of enhancement of prostate cancer on contrast-enhanced transrectal ultrasonography: correlation with biopsy and radical prostatectomy specimens

Abstract

Objectives: This study was designed to identify factors that influenced the degree of enhancement of prostate cancer on contrast-enhanced transrectal ultrasonography (CETRUS).

Methods: 139 patients suspected of prostate cancer were evaluated with CETRUS followed by systematic and targeted transrectal ultrasound-guided biopsies. The degree of enhancement of the lesions was objectively measured using peak intensity with time-intensity curve analysis software. Ultrasound findings were correlated with clinical characteristics as well as biopsy and radical prostatectomy findings.

Results: Prostate cancers were detected in 230 biopsy sites from 91 patients. The mean peak intensity value of prostate cancer was significantly higher than that of the benign lesions (9.82 ± 3.73 vs 7.51 ± 2.97; p<0.001), and the peak intensity value of the cancer foci varied across the prostate. The mixed model analysis revealed that the location and Gleason score of tumour foci were the influencing factors of the peak intensity value, and the former had a stronger influence upon peak intensity than the latter (p=0.000 and 0.040, respectively). However, age, prostate volume or serum prostate-specific antigen of the patient had no significant influence on the peak intensity value (p>0.05). Furthermore, the peak intensity value of tumours larger than 5 mm diameter was significantly higher than tumours of 5 mm or smaller diameter (9.28 ± 2.46 vs 6.69 ± 2.65; p<0.001).

Conclusions: The prostate cancer lesions with a higher Gleason score and larger tumour size which were located in the lateral peripheral zone (PZ) were more likely to show a marked enhancement. Lesions with lower peak intensity that are located in the medial PZ should also be treated as suspicious.

Figure 1

Biopsy map of the prostate used for marking the biopsy site. PZ, peripheral zone; TZ, transition zone.

Figure 2

Peak intensity values of benign prostate hyperplasia (BPH) and prostate cancer (PCa) lesions located in medial peripheral zone (PZ), lateral PZ and transition zone (TZ).

Figure 3

Ultrasound images in a 60-year-old male with Gleason 7 cancer at the right lateral peripheral zone of the prostate. (a) Conventional greyscale image demonstrated a focal hypoechoic lesion (arrows). (b) Contrast-enhanced image demonstrated a clearly defined area of focal enhancement, corresponding to the cancer (arrows). (c) On analysis with Axius^TM ACQ software (TomTec, Fulda, Germany), the peak intensity of enhancement in this lesion was 11.09 dB (white circle).

Figure 4

Ultrasound images in a 73-year-old male with Gleason 8 cancer, extending along the left peripheral zone from the medial part to the lateral part of the gland. (a) Conventional greyscale image demonstrated no definite lesion. (b) Contrast-enhanced image demonstrated focal enhancement in the left lateral gland (arrows). Although the tumour extended through the medial gland, no marked enhancement is seen in the medial peripheral zone. (c) On analysis with Axius^TM ACQ software (TomTec, Fulda, Germany), the peak intensity values of cancer foci within the para-midline, the middle and the lateral biopsy site were 5.70 (white circle), 10.18 (blue circle), 12.90 (red circle), respectively.