Utility of Photon Counting Detector CT Angiography for Detecting Spinal Arteriovenous Fistulas

Photon counting detector CT is a relatively nascent technology with numerous developing applications in neuroradiology. Its novel x-ray detection mechanism confers several advantages, including higher spatial resolution, inherent spectral sensitivity, and improved contrast-to-noise ratio. These have been shown to have benefits in vascular imaging. One potential vascular application is spinal photon counting CT angiography for detection and characterization of spinal arteriovenous fistulas, a treatable cause of myelopathy. In this clinical report, we performed a retrospective case series from two institutions, identifying eight patients who underwent a photon counting spinal CT angiogram for the purposes of detecting an arteriovenous fistula. We assessed the diagnostic value of this technique and compared two different reconstructions in our protocol. We found that a site of arteriovenous fistula was successfully localized in all eight patients, and this was confirmed on subsequent surgery or conventional angiography. In all cases, these fistulas were best seen on 0.2 mm low-energy threshold reconstructions.