Isotopic Scintigraphy Coupled With Computed Tomography for the Investigation of Intrathecal Baclofen Device Malfunction

Objective: To assess the potential use of indium-111 diethylenetriamine pentaacetic acid ((111)In-DTPA) scintigraphy coupled with computed tomography (CT) for the investigation of intrathecal baclofen (ITB) device malfunction.

Design: Retrospective study of a case series of patients.

Setting: Neurosurgical and physical and rehabilitation medicine departments.

Participants: Patients (N=7) with reduced ITB effectiveness in whom prior conventional radiographs were inconclusive.

Intervention: Nine (111)In-DTPA scintigraphic studies and 8 CT scans. Planar acquisitions were followed by tomoscintigraphy combined with CT.

Main outcome measure: Progression of the radiotracer in the pump, catheters, and in the subarachnoid space.

Results: In 7 cases, scintigraphy coupled with CT showed leakage behind the pump, lack of activity outside the pump reservoir, abrupt interruption of activity in the catheter, or abnormal distribution of the radiotracer, thus demonstrating that the drug did not reach its target. Surgical revision confirmed these findings in 5 cases. In 1 case, combined imagery ruled out device dysfunction. In the remaining case, only planar acquisitions were performed, showing correct diffusion of the radiotracer.

Conclusions: The combination of scintigraphy and CT provides simultaneous functional and anatomic imagery of the device. The slow infusion of the radioisotope mimics the diffusion of baclofen, and this could be a useful method to explore intrathecal device malfunction. Further studies are required to compare scintigraphy coupled with CT, to radiopaque injection followed by fluoroscopy or CT.