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Influence of PDE5 inhibitor on MRI measurement of clitoral volume response in women with FSAD: a feasibility study of a potential technique for evaluating drug response


The purpose of this study was to determine if magnetic resonance imaging (MRI) could quantify a difference in clitoral response following administration of a vasoactive medication, in 12 women with female sexual arousal disorder (FSAD). Subjects were entered into a double-blind, randomized two-way crossover study of sildenafil 50 mg vs placebo administered 1 h prior to genital MRI. Each subject underwent two MR studies, performed while subjects viewed alternating segments of nonerotic and erotic video. MR images were analyzed for change in clitoral volume during each session. The mean change in clitoral volume for the entire group was higher in the sildenafil MRI session (1282 mm3) compared with placebo (849 mm3) but did not reach statistical significance (P=0.064). Comparison using analysis of variance between the two sessions for each individual subject revealed a significant increase in clitoral volume following sildenafil compared with placebo in 6 of 12 subjects, no significant change in either imaging session in three subjects and in three subjects, there was a robust clitoral response in both MR sessions. In conclusion, MR measurements of clitoral volume can provide an objective measure of engorgement change following a vasoactive medication in women with FSAD.

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Research support for this study was provided by Pfizer Inc.

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Correspondence to K R Maravilla.

Appendix 1. Subjective self-assessment questionnaire of sexual arousal

Appendix 1. Subjective self-assessment questionnaire of sexual arousal

Instructions: Please use the following to evaluate how you felt before or after the tape/film. Please answer honestly and carefully. On the scale, circle any of the numbers from 1 (not at all) to 7 (intensely).Table A1

Table 1 Table a1

(Values from the three questions were averaged to a single arousal score for analysis).

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Yang, C., Cao, Y., Guan, Q. et al. Influence of PDE5 inhibitor on MRI measurement of clitoral volume response in women with FSAD: a feasibility study of a potential technique for evaluating drug response. Int J Impot Res 20, 105–110 (2008).

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