Imaging

Antegrade vasography and seminal vesiculography were first described in 1913 (33). When used for the evaluation of the infertile man, seminal vesicle abnormalities may

FIGURE 2 ■ T2-weighted magnetic resonance imaging reveals semi-FIGURE1 ■ Pathological specimen shows seminal vesicle with nal vesicle stone (arrow) as discrete, signal void, nodular structures.

calculus (arrow). Source: From Ref. 22. Source: From Ref. 22.

FIGURE 2 ■ T2-weighted magnetic resonance imaging reveals semi-FIGURE1 ■ Pathological specimen shows seminal vesicle with nal vesicle stone (arrow) as discrete, signal void, nodular structures.

calculus (arrow). Source: From Ref. 22. Source: From Ref. 22.

Seminal vesicle cysts should be distinguished from mullerian duct cysts, which are found in the midline flanked on each side by a normal seminal vesicle. Since most seminal vesicle cysts are asymptomatic, no treatment is required.

To date there have been no reports of laparoscopic excision of the seminal vesicle for a primary malignancy.

Proteinaceous seminal vesicle stones are seen as discrete, signal void structures on T2-weighted images making magnetic resonance imaging superior to computed tomography for imaging the seminal vesicles (Fig. 2).

The surgeon performing excision of a congenital seminal vesicle cyst should also be prepared to remove ureteral and renal remnants when necessary.

be identified. Owing to its invasive nature and risk of vasal fibrosis or scarring, its use for seminal vesicle surgery has largely been supplanted by ultrasound, computed tomography, and magnetic resonance imaging.

Imaging of the seminal vesicles with intravenous urography has been replaced by other modalities. Rarely, intravenous urography diagnoses a radio-opaque stone, an ectopic ureter draining directly into the seminal vesicle, or a mass effect from a cyst or neoplasm.

As prostate cancer screening has become more routine, the number of transrectal ultrasound procedures has increased. Along with obtaining prostate biopsies, the urologist is afforded a view of the seminal vesicles. In addition to quantifying seminal vesicle size, stones appear as highly echogenic structures and cysts as hypoechoic fluid-filled cavities. Solid masses can be appreciated disfiguring the normal contour of the seminal vesicle and are typically hyperechoic.

Computed tomography can often provide useful information regarding the seminal vesicle and any associated renal or ureteral abnormalities. Since the seminal vesicle enhances following contrast administration, inflammatory lesions, cysts, and masses can be identified and distinguished from the surrounding structures. Simple cystic lesions display Hounsfield units of 0-10. When filled with stones, debris, blood, or pus the Hounsfield units are higher. Even with modern computed tomography capabilities, masses of the seminal vesicle can sometimes be difficult to differentiate from the adjacent bladder, prostate, or rectum. Furthermore seminal vesicle stones may be composed of protein without any calcification making visualization on noncontrast computed tomography very difficult or impossible (22).

Magnetic resonance imaging has proven to be an accurate and useful imaging tool for the seminal vesicles. Since the seminal vesicles are of intermediate signal intensity on Tl-weighted images they can reliably be distinguished from the adjacent fat, bladder, and rectum. On T2-weighted images, the seminal vesicles are of varying intensity, depending on the age and androgen status of the man (34). As the levels of circulating androgens increase, the intensity of the seminal vesicles does also. Therefore, the seminal vesicles of postpubertal men with normal androgen levels have high signal intensity whereas those of prepubertal boys, many elderly men, and men undergoing androgen ablation have low signal intensity. The use of endorectal coils, the advent of higher Tesla magnets, and fast spin-echo techniques have all enhanced, and will continue to improve MR imaging of the seminal vesicles. Seminal vesicle cysts typically show high T2 and low T1 signal intensity but can vary based on composition (proteina-ceous, hemorrhagic, etc.) and concentration of the fluid. The signal intensity of an inflammatory lesion of the seminal vesicle depends on the chronicity of the disease and whether bleeding is present. Chronic seminal vesiculitis typically appears as low intensity signals on both Tl and T2-weighted images (35).

Proteinaceous seminal vesicle stones are seen as discrete, signal void structures on T2-weighted images making magnetic resonance imaging superior to computed tomography for imaging the seminal vesicles (Fig. 2) (22).

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