Purpose: The most important cause of Erectile dysfunction (ED) after radiotherapy is believed to be radiation damage to the neurovascular bundle (NVB), most commonly arteriogenic. However, technique and data on the measurements of the NVB function are lacking. We developed a Doppler ultrasound imaging and multiparametric waveform data analysis method to evaluate the blood flow of NVB.
Methods: Eight patients undergoing high-dose-rate brachytherapy for prostate cancer were enrolled in an IRB approved prospective pilot study. Each patient received two transrectal ultrasound scans prior to radiotherapy. 3D B-mode images of the prostate and Doppler signal of the right and left NVBs were acquired using a Hitachi Avius ultrasound machine with a 7.5MHz bi-plane probe. B-mode images of the prostate provided anatomical information. Ten vectorized morphological features were extracted from the Doppler pulse wave (PW) data. Data from two measures are compared to evaluate the reliability of PW waveform features.
Results: Among the 8 patients, the mean (relative standard deviation) of PSV was 10.11 cm/s (44%), EDV was 1.39 cm/s (69%), Trv was 1.35 cm/s (70%), mean velocity was 4.09 cm/s (36%), total time was 0.88 seconds (15%), resistance index was 0.85 (11%) and pulsatile index was 2.16 (36%), RT1 was 0.17 (39%), RT2 was 0.82 (7%), RT3 was 0.21 (49%), RT4 was 0.67 (19%). For most patients, major differences existed between left and right NVB (e.g. PSV is 34%, EDV is 87%). Comparison between the scans further identified 4 PW parameters with mean variation less than 20% (total time 17%, resistance 16%, RT2 8%, and RT4 19%).
Conclusion: We have developed a method combining Doppler ultrasound imaging, image processing, vectorized PW morphological features analysis to characterize blood flow of NVB. Our preliminary data have demonstrated its feasibility and identified reliable PW features.
Funding Support, Disclosures, and Conflict of Interest: DOD W81XWH-17-1-0438, W81XWH-17-1-0439, W81XWH-13-1-0269 RO1CA215718