354 Feasibility and Clinical Imaging of Pain States Based on Multi-Delay Arterial Spin Labeling in Chronic Low Back Pain Patients Implanted With Thoracic Spinal Cord Stimulation

Abstract

INTRODUCTION: Multi-delay, pseudo-continuous arterial spin labelling (PCASL) is a novel technique capable of perfusion imaging without contrast. It overcomes the limitation of a low signal-to-noise ratio of pulsed-ASL, and multiple post-label delays allow it to account for and measure arterial transit time (ATT). This makes it a suitable tool for the perfusion assessment. To date, there have been no studies to assess changes in ASL-measured perfusion in chronic low-back pain (cLBP) patients treated with thoracic spinal cord stimulation (tSCS). METHODS: PCASL data was acquired in five patients post-tSCS and five healthy subjects. ATT was estimated using weighted delays from multiple delay times, and it was used to calculate cerebral blood flow (CBF) and cerebral blood volume (CBV). Maps were normalized into MNI space and smoothed. Averaged values of ATT, CBF and CBV from pain ROI atlas were extracted and compared between cLBP and healthy control groups. Statistics comparing perfusion changes between patients and healthy subjects were conducted after Box-Cox transformation of data using Wilcoxon rank sum. RESULTS: Our results demonstrated the feasibility of MRI scanning with ASL sequence in patients with SCS. Specific absorption rates ranged from 0.031–0.042W/kg. Wilcoxon test indicated that ATT was significantly greater in cLBP patients within the supplementary motor area, posterior short gyrus, and the orbitofrontal cortex. There were no significant differences in patients and controls in CBF or CBV. CONCLUSIONS: Rate of perfusion as indexed by PCASL-derived ATT is reduced in cLBP treated with SCS patients in regions associated with pain processing, cognition, and motor planning. Insignificant results in CBF and CBV measures are likely due to low sample size of patients.