Radionuclide shunt studies have been used for decades to evaluate intracranial shunt patency (SP); however, the methodology is neither standardized nor well validated.

The radionuclide SP study is valuable for evaluation of VA SP. Results can be interpreted using a single variable (T½). T½ of 3.9 to 8 minutes indicates a patent shunt; T½ less than 3.9 minutes is consistent with overdrainage. T½ of >8 requires further evaluation to differentiate between obstruction and overdrainage/underdrainage ¹⁾.