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.