Dopplerography of the vessels of the penis

The penis consists of two cavernous bodies and a spongy body that surrounds the urethra and forms the bulb proximally and the head distally. The smooth muscles of the cavernous bodies form cavities lined with endothelium (sinusoids) that communicate with the arterial vascular system of the penis. Both cavernous bodies are lined with a tight fascial interlayer, called tunica albuginea (the gall bladder).

The penis is supplied from two arteries of the same name, which are the terminal branches of the internal genital arteries. At the root of the bulb of the penis, the artery of the penis on each side is divided into the artery of the urethra, the superficial dorsal artery and the deep artery of the cavernous body. Inside, its deep artery is divided into many spiral arteries opening into cavernous sinusoids. The cavernous bodies are drained by the adrenal venules, which open into the deep dorsal vein of the penis.

Erection Physiology

In peace, the smooth muscles of the cavernous bodies of the penis are in a state of complete contraction. Peripheral resistance is high, and as a result, moderate arterial blood flow is noted. At the beginning of an erection, the smooth muscles of the cavernous bodies relax due to the neurotransmitter response, the resistance of the cavernous bodies decreases, the feeding arteries expand. This leads to an increase in the arterial blood flow and an increase in the volume of the penis (swelling phase). Since the dense envelope of the skin is slightly tight, the increase in blood volume compresses the venules between the filled sinusoids and the envelope. Venous outflow stops, the penis becomes hard.

[1], [2], [3], [4], [5]

The procedure of the study and the normal ultrasound-anatomy of the penis vessels

The examination is performed in the patient's position lying on the back using a high-frequency linear sensor. Deep arteries of the penis are examined in longitudinal and cross sections from the ventral side of the base of the penis with the record of their Doppler spectra. The measurements are standardized for the basal part of the penis, as the calibra changes distally, and the peak systolic velocity decreases.

Examination of the vessels of the penis in the preinjection phase (prior to intra-cavernous administration of drugs that cause an erection) is not necessary, since the same pattern of arterial blood flow is observed both in healthy individuals and in patients with erectile dysfunction.

The peak systolic blood flow velocity in the arteries of the penis at rest is only 5-20 cm / s, combined with high resistance. Antegrade diastolic blood flow is not detected (terminal diastolic velocity = 0 cm / s). Resistance index = 1. To obtain high-quality color images and an adequate spectrum, a minimum pulse repetition frequency and a near-wall filter are required.

The elastic turnstile is applied to the base of the penis, then a vasoactive drug is introduced, which causes relaxation of the smooth muscles in order to expand the sinusoids and arteries. The needle is inserted from the dorsal side of the penis, the drug is injected into the cavernous body on one side, since the presence of anastomoses will allow it to spread into all directions. Prostaglandin E1 (10-20 mg) is preferred in comparison with papaverine or a mixture of papaverine and phentolamine, because it reduces the risk of prolonged erection. After administration of the drug and removal of the turnstile, both deep arteries of the penis are scanned with the determination of peak systolic velocity (PSV), terminal diastolic velocity (EDV), and resistance index (RJ). Post-injection expansion of the arteries and sinusoid leads to an increase in peak systolic velocity to 40 cm / s. Due to a sharp decrease in peripheral resistance, the diastolic blood flow velocity rises to more than 10 cm / s, while the resistance index decreases to 0.7.

As the sinusoid becomes filled, the resistance to the blood flow in the penis increases again. As a result, the peak systolic velocity decreases, and the blood flow level remains much higher than in the relaxed state. The diastolic wave approaches the isoline and finally descends below it during diastole, as a symptom of bi-directional blood flow in the deep arteries of the penis. The resistance index rises to 1.0. The peak systolic velocity, the final diastolic velocity and the resistance index should be measured anew. The study time is about 30 minutes, because the dynamics of changes in blood flow in different individuals can vary significantly.

Dorsal arteries of the penis are less important in maintaining the erectile function, so it is not necessary to scan them. After recording all the spectra, ultrasound dopplerography of the penis is performed to identify abnormalities of the arterial vascular bed. At the end of the examination, the patient should be informed that in the case of a pharmacologically-induced prolonged erection for 4 hours, the urologist should be contacted to avoid irreversible loss of erectile function.

Arterial disorders of erectile function

Since congenital anomalies of the vascular bed of the penis can be accurately diagnosed by the image in color mode, the diagnosis of erectile dysfunction is often based on the results of Doppler spectral analysis of the deep arteries of the penis. In patients with small pelvic artery stenosis, scanning after prostaglandin injection reveals a peak systolic velocity in the swelling phase below normal. Peak systolic velocity less than 25 cm / s in the deep arteries of the penis is peak Values of 25-35 cm / s are considered borderline. The systolic rise is significantly flattened, an expanded spectral wave appears. Unlike peak systolic velocity, the degree of expansion of the arteries after pharmacological stimulation is an unsuitable parameter for assessing erectile dysfunction and is not part of the standard ultrasound.

Due to subjective unpleasant sensations of post-injection examination, subtotal pharmacological erections often occur. Before the diagnosis of erectile dysfunction, the patient is encouraged to self-stimulate for 2-3 minutes while the doctor leaves the room. After that, a second scan of the vessels of the penis and evaluation of the Doppler spectra are performed.

[6], [7], [8], [9], [10]

Venous disorders of erectile function

The signs of venous disorders of erectile function are indirectly revealed in the analysis of Doppler spectra recorded from the deep arteries of the penis. Normal compression of the draining veins with increasing blood volume is manifested by a decrease in direct diastolic blood flow or reverse circulation in the deep artery of the penis. The index of resistance reaches a level above 1.0.

In the presence of venous insufficiency, the increase in intraepithelial pressure is significantly reduced and resistance decreases due to the permanent venous outflow from the cavernous bodies. There is a persistence of antegrade diastolic blood flow, and the resistance index does not increase more than 1.0.

Detection of venous blood flow in the penis does not always indicate a venous insufficiency, because some venous outflow is present even with a full erection. It is difficult to determine the normal values of the final diastolic velocity and resistance index, since both parameters vary depending on individual characteristics. Recent studies have shown that even retention of antegrade terminal diastolic velocity in the deep arteries of the penis can be combined with a normal venous function. Despite this, the limitation of ultrasound dopplerography gives important information about venous insufficiency, followed by cavernosography and cavernosometry.