EXPERT’S CORNER

Duplex Doppler Penile Ultrasound Adrian Momesso, MD, and Edgardo Becher, MD, PhD

Corresponding author Edgardo Becher, MD, PhD Ave Cordoba 2424, Ciudad de Buenos Aires C1120AAT, Argentina. E-mail: [email protected] Current Sexual Health Reports 2006, 3:107–109 Current Science Inc. ISSN 1548-3854 Copyright © 2006 by Current Science Inc.

Duplex Doppler penile ultrasound (DDPU) is a useful, minimally invasive method for evaluating penile hemodynamics in patients with erectile dysfunction. The measurement of peak flow velocity, end-diastolic flow, and resistance index is helpful in assessment of the penile vascular status, especially in patients who do not respond to oral therapy, patients with priapism, and patients with penile pathology. Since the advent of oral therapy, the routine use of DDPU is limited to certain cases.

Introduction Duplex Doppler penile ultrasound (DDPU) is a minimally invasive diagnostic tool that provides knowledge of the patient’s penile hemodynamic status. DDPU is carried out dynamically with the injection of vasoactive agents in the corpus cavernosum to replicate the cavernosal smooth muscle relaxation that occurs during sexual stimulation. Lue et al. [1] popularized DDPU in 1985, and it has proved very useful in diagnosing and choosing treatment, especially when vascular surgery is a possibility. With the prevalence of goal-directed approaches and the advent of phosphodiesterase type 5 inhibitors, the routine use of DPPU is currently limited, and DPPU is performed mainly on patients who do not respond to oral therapy, patients who are younger and are candidates for vascular surgery, patients with priapism, patients with Peyronie’s disease, and patients who need to know the cause of their sexual dysfunction.

Technique We perform DDPU in a warm and private examination room to reduce the patient’s anxiety [2,3]. The appearance of colleagues and technicians must be kept to a minimum. The examination begins with the patient in a supine position. We initiate the procedure by scanning the corporal bodies with an 8-MHz “small-parts” linear transducer in both transverse and longitudinal planes from base to tip to

rule out cavernous pathology (eg, fibrosis, Peyronie’s disease, anatomic abnormalities). Normal cavernous echotexture should be homogeneous, compared with fibrosis, which appears hyperechoic, and Peyronie’s plaques, which appear denser than normal tunica albuginea with or without calcification. Peyronie’s plaques without calcification appear more hyperechoic with a posterior shadow. After the initial penile ultrasound and preparation of the skin with alcohol, the vasoactive agents are injected into the cavernous tissue using a 1-mL syringe with a 27-gauge needle. For patients who are younger or for whom psychological factors are suspected, we start with 5 μg of alprostadil; otherwise, a 10 μg dose is used. The patient is then left alone in the room, and he is encouraged to perform manual self-stimulation in the standing position. At 5 and 20 minutes after the injection, the transducer is sagittally placed as near as possible to the infrapubic region. The duplex or color triplex function is engaged in the ultrasound unit, and the Doppler angle is adjusted to match the correct axis of flow at 60 degrees (Fig. 1). Once an appropriate Doppler curve is obtained with the maximum amplitude possible, we measure peak flow velocity (PSV) and end-diastolic flow (EDV), which is the flow velocity measured during diastole immediately before the systolic wave takes off in order to remove the systolic waveform. Then we calculate the resistance index (RI), which is (PSV – EDV) / PSV. Most machines perform this calculation automatically. If the erectile response obtained does not reach that of one that occurs during regular sexual stimulation for the patient, the vasoactive agents are administered again, increasing in steps of 10 μg of alprostadil. If a prolonged erection persists 2 hours after the injection, we drain the cavernous bodies to decrease the intracorporeal pressure by inserting a 21-gauge butterfly needle. If the erection still persists, we inject a 2-mL dilution of 5 mg of phenilephrine in a 20-mL saline solution. We continue with this procedure until full detumescence occurs, while the patient’s blood pressure is monitored. DDPU has also been performed with oral sildenafil. Arslan et al. [4] compared the effect of 50 mg of sildenafil with intracavernous papaverine and concluded that sildenafil increased PSV, with no prolonged erections. Maximal systolic flow velocity was achieved at 60 to 75 minutes of sildenafil intake, and the dose of sildenafil should be combined with visual and genital stimulation. The values at this point were comparable with those administered at

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Expert’s Corner

DDPU and Veno-occlusive Dysfunction We suspect venous leakage or veno-occlusive dysfunction when the patient has an adequate arterial response to vasoactive drugs (PSV > 30 cm/s) with an elevated EDV (EDV > 3–5 cm/s), provided that the patient achieved a reliable erectile response from the vasoactive agents after self stimulation. RI is the best parameter for evaluating veno-occlusive dysfunction, because the value adjusts to a level depending on intracavernous pressure. As soon as intracavernous pressure matches or exceeds systemic blood pressure, diastolic blood flow velocity is zero, and the value for RI is one.

DDPU Nowadays

Figure 1. A, The ultrasound transducer is applied sagittally in the proximal dorsal aspect of the penis. B, Duplex Doppler penile ultrasound tracing on the proximal cavernosal artery showing a normal peak flow velocity (54.5 cm/s), a slightly elevated end-diastolic flow (5.9 cm/s), and normal resistance index (0.89).

5 and 10 minutes after papaverine injection, with 90% sensitivity and 100% specificity. However, today’s standard of care still includes intracavernosal injections.

DDPU and Penile Inflow Penile inflow is a function of both velocity and vessel diameter. An adequate response in the cavernous arteries should produce an arterial diameter greater than 0.7 mm and a PSV greater than 25 to 30 cm/s after injection. A smaller PSV response is consistent with arterial insufficiency. However, a low PSV in young patients without trauma should be interpreted with caution, because the low PSV may be influenced by sympathetic overtone [5]. If cavernous inflows are asymmetric or absent at the perineum, we suspect pudendal or large-vessel disease. Speel et al. [6] proposed the measurement of acceleration time as the most powerful parameter to diagnose small vessel disease.

Oral therapy for erectile dysfunction has a success rate greater than 70%. For patients who do not respond to oral therapy, we suggest that the physician perform a DDPU to rule out end-organ pathology, such as penile fibrosis, venoocclusive dysfunction, and Peyronie’s disease. Patients with normal DDPU results may continue with intracavernosal therapy or consider other therapeutic options. The test is sometimes the patient’s first experience with intracavernosal injections and helps him to decide on a treatment. Arterial high-flow priapism is a nonischemic form of priapism, which is very different from the more common veno-occlusive or ischemic form. After a perineal or arterial trauma is caused during penile injection, the cavernous artery is lacerated, producing an arterial lacunar fistula. Clinically, high-flow priapism is different from the veno-occlusive form; arterial high-flow priapism includes delayed onset of a constant, painless, and nontender erection. The rigidity is incomplete when compared with the sexually stimulated erection, and potential for full rigidity with sexual stimulation exists. The erection will continue unless the arterial lacunar fistula is closed. DDPU is the first diagnostic option for patients with high-flow priapism, with 100% sensitivity and 73% specificity rates compared with those of internal pudendal angiography [7]. The typical image is that of an arteriousvenous fistula with a continuous Doppler flow (Fig. 2). DDPU is useful for the patient’s follow-up if a watchful waiting approach has been chosen or if selective internal pudendal artery embolization has been performed. DDPU is useful for evaluation of patients with Peyronie’s disease who present with loss of rigidity, loss of length, and penile curvature and do not respond to oral or intracavernosal therapy. Levine and Coogan [8] found an incidence of erectile dysfunction in 32% of 99 patients. Eight percent of those patients with erectile dysfunction presented with corporeal veno-occlusive dysfunction, and 43% had a history of vascular risk that may have contributed to erectile dysfunction. The authors concluded that arterial insufficiency is a major contributor to erectile dysfunction associated with Peyronie’s disease. Also, the identification of communicating arteries from the dorsal to

Duplex Doppler Penile Ultrasound 4. 5. 6.

7. 8. 9.

Figure 2. Duplex Doppler ultrasound on a patient with high-flow priapism showing a continuous flow and a lacunar A-V fistula.

the cavernosal system is important for patients requiring a surgical approach. The presence of these communicating vessels indicates that this vascular supplementation is needed and should be preserved in case of surgery. DDPU helps physicians to choose the most suitable surgical procedure to correct penile curvature or loss of length (corporoplasty or plaque incision plus surgical graft) and to rule out arterial insufficiency that might lead to erectile dysfunction after surgical correction [9].

Conclusions Ultrasound penile blood flow studies are minimally invasive procedures that provide information on the penile arterial and venous systems. Variables, such as change in cavernous artery diameter and PSV, are indicators of arterial inflow, whereas EDV and the RI measure venous leak. However, DDPU lacks specificity for venous insufficiency when arterial insufficiency is present. Overall, color duplex Doppler ultrasound is an excellent noninvasive test for estimating the arterial and venous components of ED.

References and Recommended Reading

Papers of particular interest, published recently, have been highlighted as: • Of importance •• Of major importance 1.

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Lue TF, Hricak H, Marich KW, Tanagho EA: Vasculogenic impotence evaluated by high-resolution ultrasonography and pulsed Doppler spectrum analysis. Radiology 1985, 155:777–781. Sanchez-Ortiz RF, Broderick GA: Vascular evaluation of erectile dysfunction. In Male Sexual Function: A Guide to Clinical Management. Edited by Mulcahy JJ. Totowa: Humana Press; 2001:167–201. Meuleman EJ, Diemont WL: Investigation of erectile dysfunction. Diagnostic testing for vascular factors in erectile dysfunction. Urol Clin North Am 1995, 4:803–819.

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Arslan D, Esen AA, Secil M, et al.: A new method for the evaluation of erectile dysfunction: sildenafil plus Doppler ultrasonography. J Urol 2001, 166:181–184. Shamloul R: Peak systolic velocities may be falsely low in young patients with erectile dysfunction. J Sex Med 2006, 3:138–143. Speel TG, van Langen H, Wijkstra H, Meuleman EJ: Penile duplex pharmaco-ultrasonography revisited: revalidation of the parameters of the cavernous arterial response. J Urol 2003, 169:216–220. Hakim LS, Kulaksizoglu H, Mulligam R, et al.: Evolving concepts in the diagnosis and treatment of arterial high flow priapism. J Urol 1996, 155:541–548. Levine LA, Coogan CL: Penile vascular assessment using color duplex sonography in men with Peyronie’s disease. J Urol 1996, 155:1270–1273, Usta MF, Bivalacqua TJ, Jabren GW, et al.: Relationship between the severity of penile curvature and the presence of comorbidities in men with Peyronie’s disease. J Urol 2004, 171:775–779.