What is required for radionuclide cystography performed by the direct method?

Radionuclide cystography using the direct method requires catheterization of the patient. This technique involves the introduction of a radiopharmaceutical into the bladder through a urinary catheter, allowing for direct visualization of bladder function and potential abnormalities. By using catheterization, clinicians can instill a precise amount of the radioactive tracer directly into the bladder, which is crucial for accurate imaging and assessment of bladder dynamics during the test.

This method differs from other forms of cystography where the tracer might be administered systemically or indirectly, which would not provide the same level of detail for bladder studies. Catheterization ensures that the tracer is localized specifically to the bladder, enabling focused evaluation of conditions such as vesicoureteral reflux, bladder wall integrity, and residual volume after urination.