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AJNR - American Journal of Neuroradiology

The dynamic MRA (D, E) depicts both the arterial feeders and the drainage vein. The nidus itself is poorly depicted and superposed by the early filled enlarged cortical vein. A region-of-interest analysis of the time signal intensity course (C, F) was performed within the internal carotid artery (region 1), the drainage vein (region 2), the parietal superior sagittal sinus (region 3), which was fed by the drainage vein, and the frontal superior sagittal sinus (region 4), showing anterograde flow and no blood supply from the iAVM as established by conventional DSA. The time course of the signal intensity within the region of interest is given in arbitrary units. The difference of contrast arrival time between the internal carotid artery (region 1) and the dominant drainage vein (region 2) was 2 seconds. The difference of time to peak was 1 second, whereas the difference of contrast arrival time between the internal carotid artery and the normally fed frontal superior sagittal sinus was 4 seconds, and the difference of time to peak was 3 seconds. This reflects the flow pattern of the high-flow AVM, where the venous drainage system is already filled in the early arterial perfusion phase. The regular time of the venous perfusion phase is shown by the time course of the frontal sagittal superior sinus, and is in the normal range (4–7 seconds) as given by Noguchi et al (7).

Dynamic 3D MRA (D, E) depicted the residual dAVF arising from the ophthalmic artery and a filling of the frontal superior sagittal sinus during the very early arterial phase. The direct point of the fistula can only be suspected, whereas the supplying arteries and their hemodynamics can be observed. A region-of-interest analysis of the signal intensity time course (C, F) was performed within the internal carotid artery (region 1), the ophthalmic artery (region 2), the superior sagittal sinus (region 3), which was fed by the drainage vein, and the sinus rectus (region 4), which was not supplied by blood from the dAVF. The time course of the SI within the region of interest is given in arbitrary units. The differences of the dynamics of contrast enhancement between the internal carotid artery, the ophthalmic artery and the superior sagittal sinus were below the temporal resolution of our sequence. This reflects the very fast hemodynamics of the high-flow dAVF, where the venous drainage system is nearly simultaneously filled with the early arterial perfusion phase. This finding was confirmed by conventional angiography, where arterial and venous contrast appearance was also simultaneous.

Dynamic MRA revealed a facial eAVM consisting of a nidus within the soft tissue below the right mandible. Two feeding arteries, the infraorbital artery and the facial artery were clearly assessed, and the nidus of the eAVM could be clearly depicted in the dynamic 3D MRA (D, E). These findings were consistent with the selective, conventional DSA (A, B). A region-of-interest analysis of the signal intensity time course (C, F) was performed within the external carotid artery (region 1), the nidus (region 2), and the transverse sinus (region 3). The time course of the SI within the region of interest is given in arbitrary units. The difference of contrast arrival time between the external carotid artery and the nidus was 1.5 seconds; the difference of time to peak was 2 seconds. The difference of contrast arrival time between the external carotid artery and the transverse sinus was 4.5 seconds; the difference of time to peak was 7 seconds. The time course of signal intensity showed an intermediate behavior with characteristics of arterial and venous flow. Thus, this example nicely reflects a case of a typical eAVM.