Utility of Photon-Counting Detector CT Myelography for the Detection of CSF-Venous Fistulas

A 65-year-old woman with several years of orthostatic headaches and brain MR imaging demonstrating diffuse pachymeningeal enhancement and brain sag (not shown). Representative image from a right lateral decubitus DSM (A) shows multiple meningeal diverticula that remained stable during dynamic imaging (A, dashed arrows), with no evidence of a CVF. Axial images from a right lateral decubitus PCD CTM at the same time point (B–D) reconstructed at a T3D (B), 55 keV (C), and 40 keV (D) demonstrate a right T3 CVF (B–D, arrows), which is most apparent at 40 keV. The CVF is not apparent during imaging 30 seconds later, even at 40 keV (E, arrow). Additional images at adjacent slices, both from the earlier time point at 40 keV (F and G), show that this venous enhancement, though discontinuous, does, in fact, arise from a prominent meningeal diverticulum (F and G, arrows). In this case, the high degree of temporal resolution and spectral imaging conferred by PCD CT were necessary to confidently make the diagnosis. The patient underwent successful transvenous Onyx embolization of the right T3 CVF.

A 36-year-old woman with several years of orthostatic headaches, tinnitus, and MR imaging demonstrating brain sag without pachymeningeal enhancement (not shown). A representative image from a right lateral decubitus DSM (A) shows no evidence of a CVF. Axial images from a right lateral decubitus PCD CTM at the same time point (B–D) reconstructed at a T3D (B), 55 keV (C), and 40 keV (D) demonstrate a subtle right T11 CVF (B–D, arrows), most apparent at 40-keV. An axial 40-keV image obtained 20 seconds later (E) no longer shows this subtle venous opacification (E, arrow). The patient underwent Onyx embolization of this right T11 fistula.

An 80-year-old man with several years of orthostatic headaches but normal brain MR imaging findings (not shown). Representative image from a left lateral decubitus DSM centered at T10 (A) shows a small meningeal diverticulum (A, dashed arrow) but no evidence of a CVF. Axial 40-keV images at 2 adjacent slices from a left lateral decubitus PCD CTM (B and D) demonstrate opacification of a paraspinal vein (B, arrow) and the azygous and hemiazygous vein (D, arrow), consistent with a CVF. Axial 40-keV images at the same slices obtained 30 seconds later (C and E) no longer show contrast within these veins (C and E, arrows). The patient underwent transvenous Onyx embolization of the left T10 CVF.

A 55-year-old woman with SIH according to the ICHD-3 criteria, including dural enhancement and venous distention on brain MR imaging (not shown). Coronal and axial images from a right lateral decubitus dynamic CTM (A and B) on an EID scanner reconstructed at 0.6 mm show no clear CVF. Subsequent PCD CTM with the patient in the right lateral decubitus position, including 0.2-mm coronal and axial reconstructions (C and D), shows a clear right T11 CVF (C and D, arrows).