The correlation between the new RigiScan Plus software and the final diagnosis in the evaluation of erectile dysfunction

Purpose: The computer generated recordings for 2 nights in 40 patients studied with the RigiScan dagger device were reevaluated using the new RigiScan Plus software to test its value in improving the discrimination between psychogenic and organic erectile dysfunction. Materials and Methods: Each man was evaluated for erectile dysfunction with a detailed medical and sexual history, physical examination, biothesiometry, plethysmography, 2 nights of ambulatory RigiScan monitoring and a psychological evaluation that usually included a private interview with the sexual partner. At the conclusion of evaluation each patient was broadly classified as having organic or psychogenic erectile dysfunction. The RigiScan reports were initially independently analyzed without the investigator's knowledge of the final diagnosis by determining the single best erectile event, with a minimal cutoff value of 60% erection for 5 minutes as necessary to be considered normal and the sum of measurements from the 2 nights. The original reading and final diagnosis were correlated. At this point the data were processed with the new RigiScan Plus software using 2 new measurements: 1) rigidity activity units and 2) tumescence activity units at the base and tip of the penis, and the results were correlated with the final diagnosis. Results: Evaluation of the single best event again showed that tip rigidity was the best single predictor if the diagnostic criteria were modified to 70% tip rigidity for 5 minutes with an estimate of correct classification of 92.5%. Nearly the same accuracy was obtained by base single event rigidity, tip rigidity and base tumescence activity units (each 90%). The summary analysis of all erectile events during the 2 nights of evaluation that had a low correlation with the final diagnosis using the original software showed that the best overall predictor of final diagnosis was tip tumescence activity units (92.5%), followed by base rigidity and tumescence activity units (each 90%). Conclusions: The RigiScan Plus software introduced 4 new parameters that facilitate interpretation of the RigiScan data. The new software did not improve the correlation with the final diagnosis compared to the subjective single best event analysis but added new objective parameters, measured and displayed by the software, that facilitate use of the data by the physician.