Evaluation of Tc-99 MAA dose reduction in patients with pulmonary hypertension

Objectives SNM Procedure Guidelines states that a pulmonary perfusion scan is performed using 1-4mCi (200-500k particles) of Tc-99 MAA which block less than 1 in 1,000 pulmonary arterioles. Reduction of Tc-MAA dose to 100–200k particles should be considered in patients with pulmonary hypertension (PAH) to reduce risks of adverse reactions. This study was done to determine the standard practice of how hospitals screen patients for PAH and whether dose modification is practiced.

Methods A survey was administered to various hospitals across the United States to determine the standard practice used when performing pulmonary perfusion imaging. Responses were collected and recorded.

Results Twenty-six hospitals responded. Forty-six percent of the hospitals do not reduce the dose of Tc-MAA in patients with PAH. Data collected from hospitals that do modify the dose for patients with PAH varied by the following: dilution of dose, reduction in number of particles, or separate kit preparation. Patient records and discussion with physician was used to determine history of pulmonary hypertension.

Conclusions Hospitals where dose modification is practiced screen the patient for pulmonary hypertension by review of patient’s records or physician consultation. More than half of the hospitals surveyed modify MAA doses for patients with pulmonary hypertension. If dose modification is performed, the procedure varied per hospital. The difference in protocols warrants a review as to what the standard protocols should be.