Scrotal Nuclear Medicine Scan
Scrotal nuclear medicine scan is a study of the blood circulation in the scrotum using radioactive contrast agent to highlight obstruction.
This test is used almost exclusively to differentiate infection in the testis (testicle) from twisting and infarction. Infection is called epididymitis because it mostly involves a collection of tubules on top of the testicle called the epididymis. Twisting of the testis shuts off its blood supply and is called testicular torsion. Both conditions cause a very painful, swollen testis on one side. Both occur most often in young men, although infection usually occurs at a slightly greater age. The infection increases the blood supply, and the torsion cuts off the blood supply. This is an ideal situation for a blood flow study.
The distinction is critically important, because testicular torsion must be untwisted immediately or the testis will die. On the other hand, epididymitis responds to antibiotics, and surgery might further injure it.
A radioisotope, technetium-99, combined in a chemical (pertechnate) is injected intravenously while the patient is under a special machine that detects radiation. This radiation detector, called a gamma camera, scans the scrotum at one minute intervals for about five minutes, then less often for another 10 or 15 minutes. It then creates pictures (either x ray or polaroid) that reveal where the isotope went in the scrotum. Since both sides are scanned, even greater accuracy is obtained by comparison.
This procedure is usually done as an emergency to determine the need for immediate surgery.
The amount of radiation is so slight that even the sensitive testicular tissue is at minimum risk.
Blood flow appears unobstructed.
Three possible possible images appear. They are:
- increased blood flow indicating infection
- no blood flow indicating testicular torsion
- blood flow illuminated in a "donut" shaped pattern that indicates torsion that has resolved itself within the last few days
Rajfer, Jacob. "Congenital Anomalies of the Testes and Scrotum." In Campbell's Urology, ed. Patrick C. Walsh, et al. Philadelphia: W. B. Saunders Co., 1998.
Rozauski, Thomas, et al. "Surgery of the Scrotum and Testis in Children." In Campbell's Urology, ed. Patrick C. Walsh, et al. Philadelphia: W. B. Saunders Co., 1998.
J. Ricker Polsdorfer, MD
Radioisotope—An unstable form of an element that gives off radiation to become stable.
Scrotum—The bag of skin below the penis that contains the testes.