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Contrast enhances color Doppler endorectal sonography of prostate: efficiency for detecting peripheral zone tumors and role for biopsy procedure
Roy C, Buy X, Lang H, Saussine C, Jacqmin D
Department of Radiology B, University Hospital of Strasbourg-Hopital Civil, 1 place de l’Hopital, 67091 Strasbourg Cedex, France
J.Urol. 2003; 170: 69-72

  • Purpose: We evaluated the accuracy of contrast enhanced color Doppler endorectal ultrasound to guide biopsy for the detection of prostate cancer.
  • Materials and Methods: A total of 85 patients were evaluated with gray scale and color Doppler before and during intravenous injection of ultrasound contrast agent made of galactose based air micro bubbles. Our biopsy protocol was performed during contrast injection. An additional 18 directed cores were obtained based on contrast-enhanced imaging. Diagnostic efficiency with and without contrast medium injection for detecting prostate cancer was compared based on biopsy results.
  • Results: Cancer was identified in a total of 58 biopsy sites in 54 patients. Gray scale imaging revealed 96 abnormal hypoechoic nodules or irregular zones inside the outer gland, of which 48 were malignant on pathological evaluation. Contrast enhanced color Doppler had higher sensitivity (93%) than unenhanced color Doppler (54%), while specificity increased only 79% to 87% for enhanced imaging. Nine of 10 isoechoic suspicious zones were depicted with enhancement, while unenhanced Doppler detected 7 of them. There was no significant difference between the intensity of enhancement and tumor Gleason scores.
  • Conclusions: Contrast enhanced color Doppler endorectal sonography increases the detection of prostate cancer. Improvement in sensitivity was high, while the difference in specificity was not as pertinent. It is accurate when using a common and routine application ultrasound unit. This technique is easy to perform and not time-consuming. Obtaining additional biopsy cores of suspicious enhancing foci significantly improves the detection rate of cancer.
  • Editorial Comment
    Color Doppler ultrasound (CDUS) has already been proved to be of a great value as a complementary method for the detection of prostate cancer during transrectal guided biopsy. Although it has proven utility, unfortunately, this method is not used routinely in many centers. Some of the reasons may be explained by the fact that CDUS of the prostate requires high resolution modern equipments (with power Doppler), dedicated and experienced sonographer and appropriate control settings. The use of energy Doppler (Doppler angiography, power Doppler) is better than velocity Doppler in order to demonstrate subtle area of abnormal flow (areas with increased neovascularity). This occurs because energy Doppler is not dependent of the angle of the ultrasound beam. The use of microbubbles as an echo-contrast improves the ability of CDUS to better demonstrate the neovascularity associated with cancer. We have found that this phenomenon is particularly useful in large prostate gland (> 60 grams), prostate gland with isoechoic peripheral zone and prostate gland showing 2, 3 or more suspicious areas. Obviously 2 or 3 cores of the area with abnormal flow must be taken additionally to the cores obtained by the systematic biopsy. In our department routinely used CDUS without and with echo-contrast demonstrated respectively, 8% and 15% of cancer not seen on gray-scale US examination (isoechoic cancer) (1). The authors present a high sensitivity and specificity of the contrast enhanced CDUS (93 and 87% respectively). Other studies has been shown that Doppler angio-sonography (power Doppler) with eco-contrast increased the detection of prostate cancer from 38 % to 85% with an 80% specificity (2). There is no doubt that power Doppler ultrasound, preferably with eco-contrast should be used routinely during transrectal biopsy of the prostate. This technique is particularly helpful in normal appearance prostate gland (mainly those larger than 60 grams), prostate with more than one suspicious area and in patients with negative biopsies and rising PSA.

References
1. Prando A: The value of color in detection of prostate cancer. Radiol Brasil. 1998; 30: 233-7. [in Portuguese]
2. Bogers HA, Sedelaar JP,Beelarge HP et al.: Contrast-enhanced 3-D power Doppler of the prostate: correlation with biopsy outcome. Urology 1999; 54: 97-104.

Dr. Adilson Prando
Department of Radiology
Vera Cruz Hospital
Campinas, São Paulo, Brazil