Hepatobiliary Iminodiacetic Acid (HIDA) Scan in the Evaluation of Biliary Atresia: A Retrospective Cohort Study.

Objectives This study aims to evaluate the accuracy of hepatobiliary iminodiacetic acid (HIDA) scan in infants, based on examinations performed in the nuclear medicine department at the Royal Hospital. The scan results will be compared to clinical outcomes following liver biopsy, considering ultrasound findings and liver enzyme results. The findings will be analyzed alongside published data through a literature review. This study is expected to contribute to the standardization of imaging protocols, support a multidisciplinary diagnostic approach, and ultimately enhance affected infants' diagnosis, prognosis, and quality of life. Methods The Royal Hospital Research Committee granted official ethical approval for this research. The HIDA scans done from 2015 to the end of 2023 were retrospectively evaluated. The data was collected by accessing medical records, clinical files, and imaging in picture archiving and communications systems (PACS). Diagnostic accuracy of HIDA scans in detecting problems with the gallbladder was measured using the sensitivity, specificity, positive predictive value, and negative predictive value (NPV). HIDA scan results were compared with the histopathology findings and the clinical follow-ups. A P-value less than 0.05 was considered statistically significant. Results A total of 53 infant patients were included in this cohort retrospective analysis. The most common presentation was conjugated hyperbilirubinemia, observed in 88.7% of cases, with a mean conjugated bilirubin level of 115.3 µmol/L. HIDA scan results were abnormal in 33 patients (62.3%) and normal in 20 patients (37.7%). Based on combined histopathological findings and long-term clinical outcomes, 21 patients were confirmed to have biliary atresia (BA), while 32 were negative. The HIDA scan correctly identified 20 of the 21 actual cases. There were eight false-positive results in which the HIDA scan suggested BA, but patients improved without intervention, most later diagnosed with neonatal hepatitis. Only one case was a false negative. Conclusion The results align with the reported sensitivity and specificity in the literature. This shows that while the HIDA scan is highly sensitive and effective in detecting BA, it has moderate specificity. Therefore, histopathological evaluation remains essential for confirming the diagnosis. The high NPV makes the HIDA scan very helpful in ruling out the diagnosis of BA, hence avoiding further invasive investigations in patients with a negative HIDA result.