E3442. Value of Functional Nuclear Medicine Studies in Postoperative Biliary and Genitourinary Diagnostic Dilemmas
  1. Arleen Li; Montefiore Medical Center
  2. Deepak Kalbi; Montefiore Medical Center
  3. Jason Matakas; Montefiore Medical Center
  4. Kwang Chun; Montefiore Medical Center
The purpose of this series is to demonstrate the utility of functional nuclear medicine (NM) studies in diagnosing certain postoperative conditions. Imaging is crucial in diagnosing many pathologies, particularly after surgery when it can be difficult to differentiate between postoperative seroma and fluid collection due to leakage. This series presents several cases where NM studies were used to confirm diagnoses during diagnostic dilemmas.

Educational Goals / Teaching Points
The goal is to highlight the value of functional NM studies, such as hepatobiliary scintigraphy and renal scans, in resolving diagnostic dilemmas. These scans are particularly useful when there is clinical concern for biliary or urinary leak after surgery and a collection is present on cross-sectional imaging, such as CT or MR. We present three cases where NM scans were used to diagnose a biliary leak, a bile duct of Luschka, and a gallbladder remnant. NM scans can also help diagnose complications from genitourinary surgery, such as renal transplant, in cases of suspected urinary leak.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Several postoperative biliary scintigraphy and renal scans are included. In the first case, a patient presented with severe abdominal pain and distention after cholecystectomy, who then underwent biliary scintigraphy, which showed abnormal passage of radiolabeled bile in the right upper quadrant with subsequent movement of activity to the right peritoneal space, compatible with bile leak. Another patient presented with persistent abdominal pain 1 week after cholecystectomy, with CT showing right upper quadrant fluid tracking to the right paracolic gutter. Fluid sampling yielded elevated bilirubin levels. Biliary scintigraphy scan with single photon emission computed tomography/computed tomography (SPECT/CT) showed a small focus of radiotracer activity in the right lower hepatic lobe region, thought to represent a damaged bile duct of Luschka. In a third case, MR and ultrasound after cholecystectomy showed a cystic structure anterior to the common bile duct, with differential diagnosis including a postoperative collection versus dilated cystic duct remnant or gallbladder remnant. Endoscopic intervention was attempted but terminated due to inflammation. Biliary scintigraphy with SPECT/CT showed a gallbladder remnant with good contractility with cholecystokinin intervention. We also present a case of ureterocolic fistula after ureteric stent placement, confirmed on <sup>99m</sup>Tc-mercaptoacetyltriglycine (<sup>99m</sup>Tc-MAG3) renal scan, which showed presence of radiotracer activity in the colon on delayed SPECT/CT images. Another case of post renal transplant urinary leak was diagnosed using <sup>99m</sup>Tc-diethylene-triamine-pentaacetate (<sup>99m</sup>mTc-DTPA) due to <sup>99m</sup>Tc-MAG3 unavailability.

Functional nuclear medicine imaging can be very helpful in diagnostically challenging postbiliary and genitourinary complications. This series presents several cases that demonstrate the utility of NM studies in resolving diagnostic challenges, ultimately leading to more accurate diagnoses and improved patient outcomes.