Radionuclide cystography is performed by the direct method using which radiopharmaceutical?

Radionuclide cystography is a nuclear medicine imaging technique used primarily to assess the urinary bladder, often for the detection of vesicoureteral reflux and other bladder abnormalities. The direct method involves instilling a radiopharmaceutical directly into the bladder, which allows for real-time imaging during urination.

The correct choice, 99mTc-pertechnetate, is commonly utilized for this purpose because it is effective in demonstrating the bladder's anatomy and function. When 99mTc-pertechnetate is introduced into the bladder, it provides good imagery due to its favorable photon emission properties. Its high-energy gamma emissions allow for high-resolution images with the appropriate gamma camera, thus producing clear images that help in evaluating the bladder during cystography.

Other radiopharmaceuticals listed, such as 99mTc sulfur colloid, 99mTc tetrofosmin, and 99mTc mertiatide, are not typically used for this specific application. Sulfur colloid is generally reserved for liver and spleen imaging or bone marrow studies and does not perform suitably for urinary tract imaging as pertechnetate does. Tetrofosmin is primarily a myocardial perfusion agent, while mertiatide is mainly used for kidney function studies