Two elderly patients with dural arteriovenous fistulas (AVF), the abnormal vessels of which were not presented on magnetic resonance imaging (MRI) are reported. Although spinal AVF was suspected from hyperintensity in the spinal cord, dilated vessels were not detected on MRI. Computed tomography (CT) angiography was performed with a 64-detector row multidetector row CT (MDCT) system in both cases. The draining dilated vein was observed in both cases and they were interpreted as perimedullary AVF. In case 1, axial scan and the dorsal section of the coronal view demonstrated continuity of the radiculomedullary artery and intercostal artery through the spinal branch at the left Th12 level. After intravascular embolization in case 1 and surgical treatment in case 2, neurological improvement was obtained in both cases. MRI findings suggestive of dural AVF have described that intradural perimedullary tortuous low signal intensities posterior to the spinal cord, known as flow void, on T(2)-weighted images is the most consistent. Recently, MDCT angiography confirmed the presence of a fistula previously suspected after MRI. There are no previous reports that describe cases of dural AVF diagnosed by MDCT angiography of which abnormal vessels were undetected by MRI images. MDCT can detect abnormal vessels which were not depicted on MRI. When dural AVF are suspected on MRI, MDCT angiography should be performed before selective angiography to diagnose.