Radiopharmaceutical Transit Timing in Pediatric and Young Adult Nuclear Medicine CSF Shunt Imaging: A 5-Year Retrospective Review

Rationale and Objectives To retrospectively characterize the movement of radiopharmaceutical through cerebrospinal fluid (CSF) shunt catheters on nuclear medicine (NM) examinations with an aim of optimizing duration of image acquisition for children and young adults. Materials and Methods An institutional reivew board approved retrospective review was conducted of all NM CSF shunt imaging examinations performed at our hospital between June 2020 and June 2025. Variables collected included: shunt type (ventriculoperitoneal (VP), ventriculoatrial (VA), ventriculopleural (VPL), lumboperitoneal (LP)); radiopharmaceutical dose; and time of first visualization of radiopharmaceutical activity in the shunt catheter and drainage compartment. Visualization of activity in the drainage compartment was considered indicative of patency of the distal shunt limb. Continuous data were summarized using medians and ranges. Categorial variables were summarized using counts and percentages. Results Among 197 CSF shunts, VP shunts were the most common ( n = 174; 88.3%), followed by VPL shunts ( n = 15; 7.6%), VA shunts ( n = 7; 3.6%) and LP shunt ( n = 1; 0.5%). Forty-six (23%) shunts never showed drainage compartment activity. Among the 151 shunts that demonstrated drainage compartment activity, VP shunts displayed peritoneal activity at a median of 17 min (range:1- 81) with peritoneal activity visible only after 60 min for 6 shunts. VPL shunts displayed pleural activity at a median of 5 min (range: 1- 33) and VA shunts displayed systemic activity at a median of 7.5 min (range: 5- 33). The single LP shunt showed radiopharmaceutical activity in the peritoneum at 30 min. Conclusion In this sample of children and young adults with CSF shunts, drainage compartment activity was demonstrated within 60 min in the majority of NM CSF shunt exams. Imaging beyond this interval, infrequently provides additional information for clinical-decision making.