Asymmetric radiotracer activity of enlarged cerebral spinal fluid space on radionuclide cisternography with SPET/CT

Objective: Cerebrospinal fluid (CSF) leak is a well-known complication of skull or sinus surgery. Radionuclide cisternography has high sensitivity for detection of CSF leak, commonly performed in conjunction with radioactivity assay of nasal pledgets. Our objective was to highlight the usefulness of single photon emission tomography/computed tomography (SPET/CT) in radionuclide cisternography by presenting a case of a 41 years old man with right sided rhino rrhea following craniotomies and sinus surgery, who was subjected to radioactivity assay of nasal pledgets and radionuclide cisternography for suspected CSF leak. Although no CSF leak was detected by radioactivity assay of pledgets placed in the nasal cavity, asymmetric radiotracer activity was noted on cisternographic images in the left temporal region, which was found to correspond to an enlarged CSF space in the left middle cranial fossa, not CSF leak, on SPET/CT images. Conclusion: SPET/CT was useful in the differentiation of asymmetric CSF radiotracer activity caused by a normal variant or post surgical changes of anatomic structures from abnormal radiotracer activity secondary toCSF leakageonradionuclidecisternography.