Assessing Bilateral Neurovascular Bundles Function with Pulsed Wave Doppler Ultrasound: Implications for Reducing Erectile Dysfunction Following Prostate Radiotherapy.

Erectile dysfunction is a prevalent side effect following prostate radiotherapy, often linked to damage to the bilateral neurovascular bundles (NVBs). This study aims to investigate the blood flow of bilateral NVBs using pulsed wave Doppler ultrasound in prostate cancer patients undergoing prostate RT. Sixty-two patients (mean age: 66.1 ± 7.2 years; Gleason Score: 6: 4, 7: 41, 8: 8, 9: 9; Ethnicity: African American: 34, White: 28; and Treatment: EBRT+brachy: 33, brachy: 29) scheduled for prostate radiotherapy were enrolled. Transrectal ultrasound was performed on each patient in the lithotomy position using a 7.5 MHz bi-plane probe controlled by a mechanical stepper. NVB locations were identified via color flow Doppler imaging, and the blood flow rates of NVBs were measured bilaterally using pulsed wave Doppler. Doppler waveforms were analyzed using custom Python software, and five waveform features were computed: peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (Vm), resistive index (RI), and pulsatile index (PI). Furthermore, we compared Doppler blood flow measurements with patients' self-reported sexual function scores obtained from the Expanded Prostate Cancer Index Composite for Clinical Practice (EPIC-CP) questionnaire, generating erectile scores ranging from 0 to 12. Doppler pulsed waveform parameters exhibited considerable variation among the 62 patients: PSV = 4.81 – 34.94 cm/s, EDV = 0 – 12.15 cm/s, Vm = 0.86 – 17.66 cm/s, RI = 0.27 – 1.0, and PI = 0.39 – 11.69. Blood flow discrepancy analysis of PSV revealed varying degrees of difference between left and right NVBs: among the 62 patients, 43 exhibited less than a 50% difference, 12 displayed a difference ranging between 50 to 100%, and 7 showed a difference exceeding 100%. Table 1 shows the bilateral discrepancy of five NVB pulsed wave Doppler parameters. The percentage discrepancy for EDV was calculated based on 17 patients, excluding those with an EDV value of 0. Among the 31 patients with available erectile scores, a subset analysis of those under 65 years old (n = 13) demonstrated a significant correlation between decreased blood flow (mean value of bilateral PSVs) and sexual dysfunction (Spearman correlation coefficient: -0.81, p < 0.01). Our Doppler study of the blood flow of NVBs in patients receiving prostate radiotherapy highlights substantial differences in Doppler ultrasound waveform features between bilateral NVBs. The proposed ultrasound method may prove valuable as clinicians strive to deliver NVB-sparing RT to preserve sexual function effectively and enhance patient overall well-being. [ABSTRACT FROM AUTHOR]