Efficacy of ultrasound contrast agent in the diagnosis and treatment of prostate diseases

The efficacy of an ultrasound contrast agent (Levovist(TM)) for ultrasonography during prostatic biopsy and transurethral microwave thermotherapy (TUMT) for benign prostatic hyperplasia (BPH) was examined. Between March and September, 1999, 25 patients who were suspected of having prostate cancer according to PSA, MRI or transrectal ultrasonography (TRUS), underwent transrectal prostatic biopsy. The ultrasound contrast agent was administered intravenously at a concentration of 300 mg/ml and at a rate of 1.0 ml/min. Similarly, between January and September, 1999, for 3 patients with symptomatic BPH, changes in blood flow signals in the prostate gland during TUMT were observed using transrectal color Doppler ultrasound using the ultrasound contrast agent. The ultrasound contrast agent was administered intravenously at a concentration of 300 mg/ml and at a rate of 0.5 ml/min. Prostatic cancer was detected in 17 (68.0%) of the 25 patients. Evaluating all the samples obtained, the sensitivity and specificity were 70.6% and 84.3% for TRUS, 64.7% and 86.1% for color Doppler ultrasound, and 64.7% and 87.0% for enhanced color Doppler ultrasound, respectively. Although this is only a preliminary report, we were able to conclude that the use of an ultrasound contrast agent during prostatic biopsy can enable the lesion to be depicted clearly, however there is little impact on the improvement of sensitivity and specificity in the diagnosis of prostate cancer. The signals of blood flow in the prostate gland increased just after the initiation of TUMT in all patients. Avascular areas in the prostate appeared about 10 minutes after TUMT treatment and expanded time dependently in all patients. These avascular areas were correlated with the coagulative necrosis areas detected by MRI 2 weeks after treatment. The real-time observation of avascular areas using an ultrasound contrast agent during TUMT for BPH has become possible, and this will be helpful in establishing the treatment conditions for each patient.