Korean J Radiol.  2009 Jun;10(3):244-251. 10.3348/kjr.2009.10.3.244.

Classification of Focal Prostatic Lesions on Transrectal Ultrasound (TRUS) and the Accuracy of TRUS to Diagnose Prostate Cancer

• Lee HY
• Lee HJ
• Byun SS
• Lee SE
• Hong SK
• Kim SH

• KMID: 1779451
• DOI: http://doi.org/10.3348/kjr.2009.10.3.244

Abstract

OBJECTIVE
To improve the diagnostic efficacy of transrectal ultrasound (TRUS)-guided targeted prostatic biopsies, we have suggested the use of a new scoring system for the prediction of malignancies regarding the characteristics of focal suspicious lesions as depicted on TRUS. MATERIALS AND METHODS: A total of 350 consecutive patients with or without prostate cancer who underwent targeted biopsies for 358 lesions were included in the study. The data obtained from participants were randomized into two groups; the training set (n = 240) and the test set (n = 118). The characteristics of focal suspicious lesions were evaluated for the training set and the correlation between TRUS findings and the presence of a malignancy was analyzed. Multiple logistic regression analysis was used to identify variables capable of predicting prostatic cancer. A scoring system that used a 5-point scale for better malignancy prediction was determined from the training set. Positive predictive values for malignancy prediction and the diagnostic accuracy of the scored components with the use of receiver operating characteristic curve analysis were evaluated by test set analyses. RESULTS: Subsequent multiple logistic regression analysis determined that shape, margin irregularity, and vascularity were factors significantly and independently associated with the presence of a malignancy. Based on the use of the scoring system for malignancy prediction derived from the significant TRUS findings and the interactions of characteristics, a positive predictive value of 80% was achieved for a score of 4 when applied to the test set. The area under the receiver operating characteristic curve (AUC) for the overall lesion score was 0.81. CONCLUSION: We have demonstrated that a scoring system for malignancy prediction developed for the characteristics of focal suspicious lesions as depicted on TRUS can help predict the outcome of TRUS-guided biopsies.

Keyword

Prostate biopsy; Transrectal ultrasound; Prostate cancer diagnosis

MeSH Terms

Aged
Aged, 80 and over
Area Under Curve
Biopsy/methods
Humans
Male
Middle Aged
Predictive Value of Tests
Prostate/ultrasonography
Prostatic Neoplasms/classification/*diagnosis/*ultrasonography
Reproducibility of Results
Retrospective Studies
Sensitivity and Specificity
Ultrasound, High-Intensity Focused, Transrectal/*methods

Figure

• 

  Fig. 1 Scoring system for focal suspicious lesions. A, B. Findings for 45-year-old male are presented. Transrectal US image shows band-like low echoic lesion (arrows) with regular outline at outer peripheral zone. Color Doppler US shows prominent hypervascularity (arrows) within lesion, indicating likelihood of malignancy. However, based on use of algorithm for scoring, lesion was given score 2, and positive predictive value for benignity was higher than that for malignancy (64.7% versus 35.3%). Pathology revealed no evidence of malignancy in prostate biopsy samples. C, D. Findings for 70-year-old male are presented. Transrectal US image shows cluster-like hypoechogenic lesion (arrows) at right outer peripheral zone. Color Doppler US image shows no definite vascularity (arrows) within lesion, indicating that lesion is probably benign. However, devised algorithm classified lesion with score 3, which has considerable positive predictive value for malignancy (48.6%). Pathology confirmed lesion as prostatic cancer. E, F. Findings for 75-year-old male are presented. Transrectal US image shows nodular low echogenic lesion (arrows) in left prostate. Portion of this lesion was located in transition zone, although most of lesion was located at inner peripheral zone. Color Doppler US image shows focal prominent vascularity (arrows) within lesion. This lesion corresponded to score 2, and pathology revealed lesion as due to prostatic cancer.

• 

  Fig. 2 Receiver operating characteristic curves of scoring system.

Reference

1. Rifkin MM, Choi H. Implications of small, peripheral hypoechoic lesions in endorectal US of the prostate. Radiology. 1988. 166:619–622.

2. Plawker MW, Fleisher JM, Vapnek EM, Macchia RJ. Current trends in prostate cancer diagnosis and staging among United States urologists. J Urol. 1997. 158:1853–1858.

3. Elabbady AA, Khedr MM. Extended 12-core prostate biopsy increases both the detection of prostate cancer and the accuracy of Gleason score. Eur Urol. 2006. 49:49–53.

4. Lee F, Siders DB, Torp-Pedersen ST, Kirscht JL, McHugh TA, Mitchell AE. Prostate cancer: transrectal ultrasound and pathology comparison. A preliminary study of outer gland (peripheral and central zones) and inner gland (transition zone) cancer. Cancer. 1991. 67:1132–1142.

5. Littrup PJ, Lee F, Mettlin C. Prostate cancer screening: current trends and future implications. CA Cancer J Clin. 1992. 42:198–211.

6. Kuligowska E, Barish MA, Fenlon HM, Blake M. Predictors of prostate carcinoma: accuracy of gray-scale and color Doppler US and serum markers. Radiology. 2001. 220:757–764.

7. Newman JS, Bree RL, Rubin JM. Prostate cancer: diagnosis with color Doppler sonography with histologic correlation of each biopsy site. Radiology. 1995. 195:86–90.

8. Lavoipierre AM, Snow RM, Frydenberg M, Gunter D, Reisner G, Royce PL, et al. Prostatic cancer: role of color Doppler imaging in transrectal sonography. AJR Am J Roentgenol. 1998. 171:205–210.

9. Cornud F, Belin X, Piron D, Chrétien Y, Flam T, Casanova JM, et al. Color Doppler-guided prostate biopsies in 591 patients with an elevated serum PSA level: impact on Gleason score for nonpalpable lesions. Urology. 1997. 49:709–715.

10. Djavan B, Margreiter M. Biopsy standards for detection of prostate cancer. World J Urol. 2007. 25:11–17.

11. Shim HB, Lee SE, Park HK, Ku JH. Significance of suspicious lesions at transrectal ultrasonography in men with serum prostate-specific antigen levels of < 20 ng/ml. Tumori. 2007. 93:178–181.

12. Hamper UM, Sheth S, Walsh PC, Holtz PM, Epstein JI. Stage B adenocarcinoma of the prostate: transrectal US and pathologic correlation of nonmalignant hypoechoic peripheral zone lesions. Radiology. 1991. 180:101–104.

13. Toi A, Neill MG, Lockwood GA, Sweet JM, Tammsalu LA, Fleshner NE. The continuing importance of transrectal ultrasound identification of prostatic lesions. J Urol. 2007. 177:516–520.

14. Lee HJ, Kim KG, Lee SE, Byun SS, Hwang SI, Jung SI, et al. Role of transrectal ultrasonography in the prediction of prostate cancer: artificial neural network analysis. J Ultrasound Med. 2006. 25:815–821.

15. Ozden E, Göğüs C, Karamürsel T, Baltaci S, Küpeli S, Göğüs O. Transrectal sonographic features of prostatic intraepithelial neoplasia: correlation with pathologic findings. J Clin Ultrasound. 2005. 33:5–9.

16. Mitterberger M, Pinggera GM, Horninger W, Bartsch G, Strasser H, Schäfer G, et al. Comparison of contrast enhanced color Doppler targeted biopsy to conventional systematic biopsy: impact on Gleason score. J Urol. 2007. 178:464–468.

17. Halpern EJ, Ramey JR, Strup SE, Frauscher F, McCue P, Gomella LG. Detection of prostate carcinoma with contrast-enhanced sonography using intermittent harmonic imaging. Cancer. 2005. 104:2373–2383.