Detection of dural defect localization using four-dimensional dynamic computed tomography myelography for patients with superficial siderosis

Background There are cases of superficial siderosis (SS) with spinal ventral fluid-filled collection in the spinal canal (VFCC). In our previous study, the balanced steady-state free precession sequence magnetic resonance imaging is useful in identifying the location of dural defects. However, because of its narrow scan area and long scan time, it cannot easily detect the defect location in some patients with small dural defect. In this study, we applied four-dimensional dynamic computed tomography (4DCT) imaging, including time-axis imaging, to myelography using the latest CT imaging equipment, which can perform short-time continuous imaging, to identify the dural defect site. Methods Twenty SS patients with VFCC (9 males, 11 females; mean age 61.6 years) underwent 4DCT myelography (4D-CTM). A 192-row helical CT (SOMATOM Force, SIEMENS) with high-speed scanning capability was used to obtain 9–11 scans per minute at low dose while flowing contrast medium into the subarachnoid space. Then, contrast leakage sites were identified. Results The contrast leakage sites could be identified in all 20 cases: C7/Th1, 2 cases; Th1/2, 5 cases; Th2/3, 9 cases; Th3/4, 1 case; Th5/6, 1 case; Th7/8, 1 case; and Th8/9, 1 case. Eighteen cases underwent surgical operation, and actual dural defects were confirmed at the contrast leakage sites. The mean ± standard deviation of leakage time from contrast agent injection was 19.0±9.2 s. Conclusions 4D-CTM can be used to reliably identify the location of spinal fluid leakage. In SS cases, dural defects could be visualized in an average of 19 seconds.