Feasibility of MRI based oxygenation imaging for the assessment of acute limb ischemia

Bihui Zhang; Chengyan Wang; Haochen Wang; Hanjing Kong; Fei Gao; Min Yang; Jue Zhang

doi:10.21037/atm.2020.02.139

Feasibility of MRI based oxygenation imaging for the assessment of acute limb ischemia

Ann Transl Med. 2020 Mar;8(6):315. doi: 10.21037/atm.2020.02.139.

Authors

Bihui Zhang¹, Chengyan Wang^{2

3}, Haochen Wang¹, Hanjing Kong³, Fei Gao⁴, Min Yang¹, Jue Zhang^{3

4}

Affiliations

¹ Department of Interventional Radiology and Vascular Surgery, Peking University First Hospital, Beijing 100034, China.
² Human Phenome Institute, Fudan University, Shanghai 201203, China.
³ Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
⁴ College of Engineering, Peking University, Beijing 100871, China.

Abstract

Background: Acute limb ischemia (ALI) can lead to death and amputation. Evaluating the severity of ischemia is important but difficult, through current methods of examination. The purpose of this research was to demonstrate the feasibility of magnetic resonance imaging (MRI) susceptibility-based imaging techniques for use in assessing muscle oxygenation alterations in ALI.

Methods: ALI animal models were established in 11 rabbits. Their left iliac arteries were embolized by microspheres. MRI scans were conducted 24 hours before (Pre) and 1 hour (Post 1) and 3 hours (Post 2) after the procedure. A susceptibility model was used to calculate skeletal muscle oxygenation extraction fraction (SMOEF) and relaxation rate (R2'). T2 weighted (T2w) imaging and diffusion-weighted (DW) imaging were performed.

Results: The average calf muscle SMOEF in the embolized hindlimbs increased from 0.43±0.02 (Pre) to 0.48±0.02 (Post 1) and 0.50±0.02 (Post 2), both P<0.05. The R2' value increased from 13.01±2.31 s^-1 (Pre) to 16.78±2.28 s^-1 (Post 1) and 17.90±3.29 s^-1 (Post 2), both P<0.05. No significant changes of SMOEF and R2' were found after embolization in the contralateral hindlimbs. Apparent diffusion coefficient (ADC) values derived from DW imaging remained unchanged at different stages compared to before the procedures (all P>0.05). No abnormal signals were observed in the anatomical T2w images at Post 1 and Post 2.

Conclusions: This study demonstrates the feasibility of using SMOEF for the assessment of oxygenation alterations in ALI models. SMOEF is more sensitive than T2w and DW imaging in detecting acute muscle ischemia at an early stage.

Keywords: Ischemia; magnetic resonance imaging (MRI); peripheral vascular diseases.