Feasibility of human spinal cord perfusion mapping using dynamic susceptibility contrast imaging at 7T: Preliminary results and identified guidelines
Résumé
Purpose
To explore the feasibility of dynamic susceptibility contrast MRI at 7 Tesla for human spinal cord perfusion mapping and fill the gap between brain and spinal cord perfusion mapping techniques.
Methods
Acquisition protocols for high‐resolution single shot EPI in the spinal cord were optimized for both spin‐echo and gradient‐echo preparations, including cardiac gating, acquisition times and breathing cycle recording. Breathing‐induced MRI signal fluctuations were investigated in healthy volunteers. A specific image‐ and signal‐processing pipeline was implemented to address them. Dynamic susceptibility contrast was then evaluated in 3 healthy volunteers and 5 patients. Bolus depiction on slice‐wise signal within cord was investigated, and maps of relative perfusion indices were computed.
Results
Signal fluctuations were increased by 1.9 and 2.3 in free‐breathing compared to apnea with spin‐echo and gradient‐echo, respectively. The ratio between signal fluctuations and bolus peak in healthy volunteers was 5.0% for spin‐echo and 3.8% for gradient‐echo, allowing clear depiction of the bolus on every slice and yielding relative blood flow and volume maps exhibiting the expected higher perfusion of gray matter. However, signal fluctuations in patients were increased by 4 in average (using spin‐echo), compromising the depiction of the bolus in slice‐wise signal. Moreover, 3 of 18 slices had to be discarded because of fat‐aliasing artifacts.
Conclusion
Dynamic susceptibility contrast MRI at 7 Tesla showed great potential for spinal cord perfusion mapping with a reliability never achieved thus far for single subject and single slice measurements. Signal stability needs to be improved in acquisition conditions associated with patients; guidelines to achieve that have been identified and shared.
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