Scrotal Nuclear Medicine Scan

Definition

Scrotal nuclear medicine scan is a study of the tissues in the scrotum, using a radioactive contrast agent to identify masses, blood flow, and areas of infection.

Purpose

The scrotal nuclear medicine scan is used to assess blood flow within the testicles and damage caused by injury. It is also used to ascertain the cause of swollen testes (testicles) which may be due to infection or the twisting of the entire tissues of the testicle. This is done in an emergency setting if the testicle swells suddenly and painfully.

This scan can be used to diagnose tumors and cysts (pockets of fluid), but testicular ultrasound has become the diagnostic tool of choice for these growths.

Precautions

There are no precautions with a scrotal nuclear medicine scan, except that the patient must remain still during the procedure.

Description

A radioisotope, technetium-99, combined with a chemical (pertechnate) is injected intravenously while the patient is under a gamma camera that detects radiation. This special 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 is in the scrotum. Because both sides of the scrotum are scanned, even greater accuracy is obtained by comparison.

Some areas accumulate the tracer in greater than normal amounts. These are called "hot" spots and may indicate tumors or other masses. Areas that have less than normal amounts of the tracer or none at all are called "cold" spots and may indicated cysts or infection.

It is important to differentiate infection from twisting torsion and infection. A common infection called epididymitis involves a collection of tubules on top of the testicle called the epididymis that carry sperm. Twisting of the spermatic cord inside the scrotum, outside the testicle often shuts off the testes' blood supply and is called testicular torsion. Both conditions cause a very painful, swollen testicle on one side of the scrotum. Epididymitis and testicular torsion occur most often in young men, although infection usually occurs at a slightly older age. Infection increases the blood supply, showing up as a "hot" spot on the scan, whereas testicular torsion cuts off the blood supply, appearing as a "cold" spot. The distinction is critically important, because testicular torsion must be untwisted immediately by surgery or the testicle will die. On the other hand, epididymitis responds to antibiotics, and surgery might further injure it.

After the patient has changed into gown, he will lie on a scanning table. The penis will be taped to the abdomen to prevent it from shadowing the scan. A towel may be used to support the testicles during the test. The tracer will be injected into a vein on the inside of the elbow, and the camera will begin taking pictures of the testicles. It is important that the patient remain still during the scans.

Two complete passes are made about 15 minutes apart. The total scrotal scan takes about 45 minutes.

Preparation

There is no preparation prior to a scrotal nuclear medicine scan. The day of the test, the patient will need to remove any jewelry, watches, and metal (belts, hairpins, etc.) and change into a gown.

Aftercare

The patient should be able to go about normal activities after the scan. However, if surgery is performed immediately after the scan, normal post-surgical precautions should be undertaken.

Complications

The risk of complications is minimal due to the small amount of radiation to which the body is exposed. Even sensitive testicular tissue is at minimum risk. The tracer is eliminated from the body within 24 hours, and allergic reactions to the tracer are rare.

Results

Results are usually available in two days. In an emergency, results are made available in one hour. Normal results show unobstructed blood flow with no "hot" or "cold" spots. Abnormal results are shown in the scan images as:

• "Hot" spots, where the tracer accumulates in greater amounts than normal, can indicate epididymitis or a tumor.
• "Cold" spots have no accumulation of the tracer or very little. These may point to cysts, abscesses, or blood clots.
• Blood flow is uneven throughout the testicles. This indicates a narrowing or blockage of the blood vessels, including from torsion, or possibly direct damage from injury. Sometimes the blood flow pattern appears in a "doughnut" shape, which suggests that testicular torsion has occurred but that it has resolved itself within the last few days.

Abnormal results may require further investigation through other tests, such as testicular biopsy or ultrasound.

Health care team roles

The nuclear medicine technologist will need to educate the patient about the procedure (for example, how the scan is done, what happens during it, what kinds of information the scan can produce for the doctor, etc.). This is very necessary to keep the patient informed and to ensure cooperation during the procedure. It is crucial that the patient remain still during the scan.

The nuclear medicine technologist who performs the scrotal scan will need to reassure the patient before and during the scan in order to keep the patient relaxed and still during the scan.

KEY TERMS

Epididymitis— A common infection involving a collection of tubules on top of the testicle called the epididymis that carry sperm.

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.

Testicular torsion— A condition involving the twisting of the spermatic cord inside the testicle that shuts off its blood supply and can seriously damage the testicle.

Resources

BOOKS

Rajfer, Jacob. "Congenital Anomalies of the Testes and Scrotum." In Campbell's Urology, edited by Patrick C. Walsh, et al. Philadelphia: W. B. Saunders, 1998, pp. 2184-2186.

Rozauski, Thomas, et al. "Surgery of the Scrotum and Testis in Children." In Campbell's Urology, edited by Patrick C. Walsh, et al. Philadelphia: W. B. Saunders, 1998, pp. 2200-2202.

OTHER

Nissl, Jan. "Testicular Scan." Health Library. Altru Health Systems. April 18, 2005 (April 18, 2006). 〈http://www.altru.org/library/healthguide/en-us/Medicaltests/topic.asp?hwid=hw234999&〉.