Asymmetry in neurovascular bundle blood flow in prostate cancer patients: A pre-treatment doppler ultrasound study.

BACKGROUND

Neurovascular-sparing treatment is believed to help preserve erectile function for localized prostate cancer, given the key role of the arterial supply of neurovascular bundles (NVBs) in potency recovery post-treatment. While NVB-sparing radiotherapy (RT) is emerging, imaging methods to assess NVB function are lacking.

PURPOSE: This study aims to evaluate the functional status of bilateral NVBs using pulsed wave Doppler ultrasound in patients undergoing prostate RT.

METHODS

Fifty-seven patients (mean age: 66.2 ± 7.1 years) were enrolled in this single-institute prospective study. Each patient underwent a transrectal ultrasound scan in the lithotomy position. Bilateral blood flow in the NVBs was measured using pulsed wave Doppler ultrasound. A custom program was developed to automatically detect and analyze the Doppler spectral waveform. Five Doppler parameters were extracted: peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (Vm), resistive index (RI), and pulsatile index (PI). Discrepancies in Doppler parameters between the left and right sides were calculated. Patient-reported sexual outcomes were assessed using the Expanded Prostate Cancer Index Composite for Clinical Practice (EPIC-CP).

RESULTS

The Doppler pulsed waveform parameters for the 57 patients were: PSV = 11.0 ± 4.0 cm/s, EDV = 1.3 ± 1.9 cm/s, Vm = 4.0 ± 2.4 cm/s, RI = 0.89 ± 0.14, and PI = 3.46 ± 1.80. Analysis of PSV revealed differing blood flow between the left and right NVBs: 40 patients had <50% difference, 10 patients had a 50%-100% difference, and seven patients had >100% difference. Among patients aged 65 years or younger (n = 11) with EPIC-CP scores, blood flow was negatively correlated to erectile dysfunction (Spearman correlation coefficient of -0.71, p = 0.01).

CONCLUSIONS

Substantial differences in blood flow between bilateral NVBs were observed. The functional information obtained from NVB Doppler ultrasound may be valuable in guiding individualized NVB-sparing treatment planning.