To evaluate the effect of low frequency ultrasound on the volume of the radiofrequency ablation lesion in canine hyperplasia prostate tissue.

A total of 9 experimental dogs were divided into three groups (3 in each group). Radiofrequency ablation was performed on the canine prostates. Low-frequency ultrasound was performed before the ablation of the experimental group. Radiofrequency ablation or low-frequency ultrasound was performed only in the control groups. Then all experiment animals underwent routine rectal examination, contrast-enhanced ultrasonography and MRI. The volume of prostate ablation lesions in enhanced magnetic resonance imaging was compared between the low-frequency ultrasound irradiation plus radiofrequency ablation group and the control group with radiofrequency ablation only. Statistical analysis was performed using the t-test to compare the differences between groups.

Contrast enhanced ultrasonography (CEUS) performed immediately after low-frequency ultrasound irradiation showed that the time to peak of intra-prostatic contrast agent shortened, the maximum intensity decreased compared with those before irradiation [(28.55±10.88) s vs (14.81±5.15) s, t=2.796, P=0.0189], and the contrast agent duration increased [(2046.56±424.66) dB s vs (1454.82±458.12) dB s], the difference was statistically significant (t=2.32, P=0.0427). CEUS and MRI can accurately evaluate the size of the prostate radiofrequency ablation. The ablation volume of the experimental group after ablation was (1.27 ± 0.21) cm³ in the experimental group, while the volume of the ablation group in the control group was (0.73±0.18) cm³, and the difference was statistically significant (t=3.382, P=0.0277); however, the other group which were only exposed to low-frequency ultrasound did not show lesions.

Low frequency ultrasound irradiation can effectively block the blood flow in proliferative prostatic tissue, and combined with radiofrequency ablation can effectively increase the volume of ablation.