Novel use of radiolabelled red blood cell SPECT-CT in diagnosing occult renal hemorrhage.

1949 Learning Objectives To educate regarding a novel use of radiolabelled red blood cell SPECT-CT in diagnosing occult renal hemorrhage. Background: Radiolabelled red blood cell (tagged RBC) evaluation of bleeding has been largely confined to localizing sites within the gastrointestinal tract. Tagged RBC use for localization of renal sites of bleeding could normally be obscured by physiologic excretion of free technetium into the urinary tract. We present a case in which suspected renal hemorrhage was confirmed with tagged RBCs SPECT-CT. Case History: 67 year-old male with end stage renal disease, renal cysts, and recent renal transplant presented with 4 days of severe hematuria and left flank pain while anticoagulated for protein C deficiency. Renal transplant doppler showed normal blood flow in the transplant vessels. Cystoscopy was unable to localize bleeding. Abdominal CT identified a rounded density in the native left kidney suspicious for hemorrhage. Image procedure: Following injection of radiolabeled autologous erythrocytes (In vitro method) initial flow and sequential dynamic planar scintillation images were obtained of the abdomen for a duration of 45 minutes followed immediately by hybrid tomographic (SPECT/CT) images of the abdomen and pelvis. Findings: Planar images of the abdomen appeared unremarkable. The SPECT/CT images demonstrated multiple foci of subtle radiotracer accumulation within the left renal parenchyma adjacent to the left renal density seen on CT, which was identified as the bleeding site. Pathology post heminephrectomy proved the accuracy of the findings.