The assessment of spinal cord (SC) hemodynamics, and especially SC blood flow (SCBF), plays a key role in the pathophysiological description and understanding of many SC diseases such as ischemia, or spinal cord injury. SCBF has been previously measured in animals with invasive techniques such as autoradiography or labeled microspheres; no MR technique, however, has been proposed so far. The possibility of quantitatively measuring SCBF in mice using MRI was investigated using a presaturated FAIR (flow-sensitive alternating inversion recovery) arterial spin labeling (ASL) technique. SCBF measurements were performed at the cervical level of the mouse as well as on the brain so as to use cerebral blood flow ( The assessment of spinal cord (SC) hemodynamics and especially perfusion plays a key role in the pathophysiologic description and understanding of many SC diseases, such as ischemia (1), spinal cord tumor, and spinal cord injury (SCI). SC injury as the most common cord disorder is, for example, generally accompanied by vascular alterations (2) that lead to a perfusion deficit. Because of the large territory supplied by the spinal arteries, the hypoperfusion may extend beyond the initial location of the lesion. An accurate, quantitative, reproducible, noninvasive, and robust technique measuring spinal cord perfusion would therefore considerably benefit the diagnosis and characterization of the temporal evolution of such SC disorders.Such a method would also improve the understanding of SC pathophysiology. For brain studies, both perfusion MRI techniques, dynamic susceptibility contrast (DSC) MRI and arterial spin labeling (ASL) (3,4), have been intensively developed and successfully applied to human and small animal cerebral blood flow (CBF) studies. In contrast, methods for studying SC hemodynamics are very scarce. Recently, the spinal cord blood volume (SCBV) in humans was measured using a vascular-space-occupancy technique (5). Spinal cord blood flow (SCBF), however, has so far only been assessed with invasive techniques such as autoradiography (6 -8), labeled microspheres (9), or hydrogen clearance in animals (10,11). In particular, no MRI measurements of SCBF have been reported. The classical DSC-MRI technique, for which absolute blood flow quantification remains difficult, is also technically challenged by the small size of the cord and the need for adequate spatial and temporal resolution. Susceptibility artifacts arising from the particular bone structure complicates the application of single-shot echo-planar imaging (EPI), which would otherwise be well suited to meet the requirements of DSC MRI in animals, where capillary and arterial blood flow are high. ASL as the alternative method for absolute quantitative perfusion measurement might suffer from too low sensitivity for human SCBF quantification. However, in the case of small animals, the high magnetic fields generally used as well as the high bloodflow values are advantageous for a better sensitivity of ASL. The fact that ASL permits repeated measu...
