Doppler Evaluation of Erectile Dysfunction - Part 1

D Golijanin; E Singer; R Davis; S Bhatt; A Seftel; V Dogra

Disclosures

Int J Impot Res. 2007;19(1):37-42. 

In This Article

Applied color Doppler ultrasonography technique

Sonographic examination of the penis is performed with the patient in either the supine or lithotomy (frog leg) position with the penis lying on the anterior abdominal wall or supported with towels between the thighs. High-frequency (7.5–14 MHz) linear array transducers are used to obtain high-resolution images of the penis. A sufficient amount of sonographic acoustic gel should be used on the surface of the penis to obtain good-quality images, and excessive compression by the transducer should be avoided, especially in patients with trauma. The examination is performed in transverse and longitudinal planes starting at the level of the glans and moving down to the base of the penis. A transperineal approach may be used if required to assess the base of the penis. The two corpora cavernosa are homogeneous in echo texture and identified as two hypoechoic circular structures. The tunica albuginea is visualized as a linear hyperechoic structure covering the corpora cavernosa. The cavernosal artery is visualized on the medial portion of the corpora cavernosa. The corpus spongiosum is often compressed and difficult to visualize optimally from the ventral aspect. Color Doppler examination of the penis should be performed in both transverse and longitudinal planes. Peak systolic velocities of the cavernosal arteries should also be recorded. Owing to the variation in the PSV of the cavernosal artery at different locations across the shaft of the penis (PSV is higher proximally), PSV should be consistently measured at the junction of the proximal one-third and distal two-third of the penile shaft where the cavernosal artery bends (Figure 2). Cavernosal artery velocities in healthy volunteers measure 10–15 cm/s in the non-erect condition. Cavernous arteries should be identified and their action potential dimension measured. When pharmacological testing is required, prostaglandin E1 injection 10–20 μg, is injected to one of the corpora cavernosa laterally in the distal part of the penis with a 30-gauge needle. Injection should always be made in the distal two-third part of the penis on one side only because of the presence of a septum in between the two corpora cavernosa in the proximal part of the penis, which is deficient distally, thus allowing bilateral perfusion of the injected vasoactive substance. Besides prostaglandin E1, other vasoactive agents used are papaverine 30–60 mg and Trimix (combination of papaverine, phentolamine and prostaglandin E1). Trimix is reserved for those patients who do not respond to prostaglandin. An oral vasoactive agent, sildenafil citrate, plus visual sexual stimulation can be used as an alternative to intracavernosal injection of vasoactive agents for penile Doppler evaluation with similar results.

Figure 2.

Cavernosal artery peak systolic velocity (PSV). Peak systolic velocity of the cavernosal artery decreases from base of the penis to the glans penis. (a) A higher PSV of the cavernosal artery (measured more proximally) as compared to distal measurement in the same patient (b).

The injection of the vasoactive substance results in physiological response of erection in normal people, and thus helps to differentiate patients with neurogenic or psychogenic dysfunction from those with vascular disturbances.

Similarly, PDE5 inhibitors could be used for pharmacological testing with increased time frame in between examinations. Tumescence and rigidity are observed and recorded, as well as the angle-corrected velocities, in both cavernosal arteries at 5, 10, 15, 20, 25 and 30 min after injection. Velocities in deep dorsal vein should also be recorded.

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