Comparison of Tc99m-DTPA and Indium-111 DTPA Studies of Baclofen Pump Function

An intrathecal drug delivery system is composed of a programmable infusion pump implanted in an abdominal subcutaneous pocket and a connecting catheter, which is inserted in the intrathecal space in the spine, usually in the thoracic or lower cervical region. Intrathecal administration of Baclofen could help reduce limb spasticity, avoiding some of the side effects of oral Baclofen therapy. Radionuclide flow studies could be used to assess catheter patency, pump function, and evaluate for leaks adjacent to the pump reservoir. Indium-111 DTPA allows the assessment of pump function without interruption or a change in the rate of intrathecal drug delivery. However, the slow infusion rate requires that imaging continue for up to 72 hours. We present an example of a Tc-99m DTPA pump function study in which imaging was completed in 1 hour. Image quality with Tc-99m DTPA is superior to In-111 DTPA because of higher counts and lower energy emission. A disadvantage of this technique is that Baclofen must be emptied from the pump reservoir before the study.