Concurrent Assessment of Penile Blood Flow and Circumference as Indicators of Male Sexual Arousal.

Introduction: The current study aims to validate a new imaging tool to assess men's sexual psychophysiological responding: laser Doppler imaging (LDI), which directly measures subcutaneous genital blood flow. In this study, we concurrently assessed genital sexual arousal in a sample of men using the LDI and the current gold standard of male sexual psychophysiology, the penile strain gauge (PSG).

Aim: To (i) assess the validity of the LDI as a measure of male sexual arousal, (ii) evaluate the relationship between the LDI and PSG, and (iii) compare sexual concordance produced by the LDI and PSG.

Methods: A total of 25 male participants (M = 24.28 years, SD = 6.10, range 18-37) watched 4 experimental films (ie, anxiety-provoking, humorous, erotic, neutral nature content) while their sexual arousal was assessed. Genital sexual arousal was assessed using the LDI (blood perfusion) and PSG (penile tumescence) concurrently. Subjective sexual arousal was assessed using continuous and discrete self-reported measures.

Main Outcome Measure: Results demonstrate the validity of the LDI as an imaging-based measure of male genital arousal, and one that is comparable to the PSG.

Results: Significant increases in genital blood flow assessed via the LDI were observed for erotic, but not anxiety-provoking, humorous, or neutral films (F[1.65, 39.57] = 18.23, P < .001, η = .43). A moderate, positive correlation between genital arousal measured via the LDI and PSG concurrently was observed (r = .40), despite considerable across-participant variability. In the current sample, the LDI and PSG both produced strong sexual concordance estimates (r = .51 and r = .46, respectively). When all LDI and PSG concordance estimates were correlated, a moderate relationship was revealed (r = .37).

Clinical Implications: As a new imaging tool for male sexual psychophysiological arousal, the LDI holds promise for improving our understanding of issues related to men's sexual health.

Strength & Limitations: Movement artifacts produced by penile engorgement were a limitation to the LDI as an imaging technique. Further, the LDI used in the current study was a discrete measure of arousal, whereas the PSG was continuous; future research would benefit by using continuous measurement capabilities of contemporary LDI systems.

Conclusion: As a valid measure of genital sexual arousal in men, the LDI holds promise as a tool that can be used to explore more nuanced questions about human sexuality, including cross-gender comparisons and real-time exploration of genital arousal patterns. Bossio JA, Singh M, Pukall CF. Concurrent assessment of penile blood flow and circumference as indicators of male sexual arousal. J Sex Med 2018;15:1570-1578.