Technetium (99mTc) Sulfur Colloid

Uses

Technetium (99mTc) Sulfur Colloid is a radiopharmaceutical diagnostic agent used for the localization of lymph nodes, evaluation of peritoneovenous (LeVeen) shunt patency, imaging areas of functioning reticuloendothelial cells, and gastrointestinal imaging.

Technetium 99m sulfur colloid is indicated as a diagnostic agent in adults for the following tests: localization of lymph nodes draining a primary tumor in patients with breast cancer or malignant melanoma; and evaluation of peritoneo-venous (LeVeen) shunt patency. It is indicated in both adult and pediatric patients for: imaging areas of functioning reticuloendothelial cells in the liver, spleen and bone marrow; and studies of esophageal transit and gastroesophageal reflux, and detection of pulmonary aspiration of gastric contents.

Technetium (99mTc) Sulfur Colloid is also used to associated treatment for these conditions: Breast Cancer, Melanoma, Malignant

How Technetium (99mTc) Sulfur Colloid works

Following injection or oral administration, single photon emission computer tomography (SPECT) imaging is performed using a gamma camera to detect technetium-99m decay. This is possible as Technetium-99m decays by isomeric transition to technetium-99 through the release of a gamma ray.

Toxicity

The most frequently reported adverse reactions, across all categories of use and routes of administration, include rash, allergic reaction, urticaria, anaphylaxis/anaphylactic shock, and hypotension. Less frequently reported adverse reactions are fatal cardiopulmonary arrest, seizures, dyspnea, bronchospasm, abdominal pain, flushing, nausea, vomiting, itching, fever, chills, perspiration, numbness, and dizziness. Local injection site reactions, including burning, blanching, erythema, sclerosis, swelling, eschar, and scarring, have also been reported. Anaphylactic reactions including rare fatalities have occurred following intravenously administered Technetium Tc 99m Sulfur Colloid. Radiation-emitting products, including Technetium Tc 99m Sulfur Colloid Injection, may increase the risk for cancer, especially in pediatric patients. Use the smallest dose necessary for imaging and ensure safe handling to protect the patient and health care worker.

Food Interaction

• Take with food. For pediatric patients, orally administered Technetium (99mTc) Sulfur Colloid should be given with milk, or if administered by nasogastric tube, it should be given with milk or dextrose.

Volume of Distribution

Following oral ingestion, Technetium Tc 99m Sulfur Colloid is distributed primarily through the gastrointestinal tract.

Elimination Route

When administered subcutaneously, Technetium Tc 99m Sulfur Colloid enters the lymphatic capillaries and is transported with lymph to lymph nodes where it can be used to detect drainage of primary tumours. When administered by intraperitoneal injection, Technetium Tc 99m Sulfur Colloid mixes with the peritoneal fluid where the rate of clearance from the cavity allows assessment of shunt patency. When administered by intravenous injection, Technetium Tc 99m Sulfur Colloid is taken up by the reticuloendothelial system (RES), allowing RES rich structures to be imaged. Uptake of the radioactive colloid by organs of the RES is dependent upon both their relative blood flow rates and the functional capacity of the phagocytic cells. When administered orally, Technetium Tc 99m sulfur colloid can be used in esophageal transit studies, gastroesophageal reflux scintigraphy, and for the detection of pulmonary aspiration of gastric contents. This is possible as the active substance is not absorbed from the GI tract.

Half Life

Technetium Tc 99m decays by isomeric transition with a physical half-life of 6.02 hours. Following intravenous administration, Technetium Tc 99m Sulfur Colloid Injection is rapidly cleared from the blood by the reticuloendothelial system with a nominal half-life of approximately 2 1/2 minutes.

Elimination Route

Following oral ingestion, elimination is primarily through the feces.

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