Objective: The purpose of this study was to reiterate the predominance of CT in evaluating ventriculoperitoneal shunt malfunction in terms of cost-effectiveness, reduction of radiation exposure, and turnaround time as the measurement parameters.
Materials and methods: This retrospective study included patients 18 years and older with a history of ventriculoperitoneal shunt insertion who presented to the emergency department with symptoms of shunt malfunction and underwent shunt series radiography and head CT within 12 hours. Shunt revision occurring contemporaneously with imaging was defined as revision within 48 hours of the original imaging report. The effective radiation dose was calculated by multiplying dose-length product from the scanner with the standard conversion coefficient k (k = 0.0021 mSv/mGy × cm). The turnaround time for patients who underwent both head CT and shunt series radiography was calculated from time of the first study to the time of completion of the last study.
Results: There were 16 shunt revisions in 239 patients. The sensitivity of CT was 87.5%; specificity, 91.4%; positive predictive value, 42.4%; and negative predictive value, 99%. The sensitivity of shunt series radiography was 18.7%; specificity, 90.9%; positive predictive value, 13%; and negative predictive value, 93.9%. There were 223 observations of CT radiation dose per patient (mean, 1.87 ± 0.45). There also were 223 observations of shunt radiography radiation dose per patient (mean, 1.57 ± 0.60). The median turnaround time among patients undergoing CT and shunt radiography was 109 ± 84 minutes.
Conclusion: Shunt series radiography is a low-yield diagnostic imaging modality for identifying shunt malfunction and prolongs turnaround time, increases medical cost, and exposes patients to unnecessary radiation.