Intravoxel incoherent motion (IVIM) detects femoral head ischemia in a piglet model of Legg‐Calvé‐Perthes disease

Abstract

ABSTRACT:There is a clinical need for alternatives to gadolinium contrast‐enhanced magnetic resonance imaging (MRI) to facilitate early detection and assessment of femoral head ischemia in pediatric patients with Legg‐Calvé‐Perthes disease (LCPD), a juvenile form of idiopathic osteonecrosis of the femoral head. The purpose of this study was to determine if intravoxel incoherent motion (IVIM), a non‐contrast‐enhanced MRI method to simultaneously measure tissue perfusion and diffusion, can detect femoral head ischemia using a piglet model of LCPD. Twelve six‐week‐old piglets underwent unilateral hip surgery to induce complete femoral head ischemia. The unoperated, contralateral femoral head served as a perfused control. The bilateral hips of the piglets were imaged in vivo at 3T MRI using IVIM and contrast‐enhanced MRI one week after surgery. Median apparent diffusion coefficient (ADC) and IVIM parameters (diffusion coefficient: Ds; perfusion coefficient: Df; perfusion fraction: f; and perfusion flux: f*Df) were compared between regions of interest comprising the epiphyseal bone marrow of the ischemic and control femoral heads. Contrast‐enhanced MRI confirmed complete femoral head ischemia in 11/12 piglets. IVIM perfusion fraction (f) and flux (f*Df) were significantly decreased in the ischemic vs. control femoral heads: on average, f decreased 47±27% (Δf=‐0.055±0.034; p=0.0003) and f*Df decreased 50±27% (Δf*Df=‐0.59±0.49×10‐3 mm2/s; p=0.0026). In contrast, IVIM diffusion coefficient (Ds) and ADC were significantly increased in the ischemic vs. control femoral heads: on average, Ds increased 78±21% (ΔDs=0.60±0.14×10‐3 mm2/s; p<0.0001) and ADC increased 60±36% (ΔADC=0.50±0.23×10‐3 mm2/s; p<0.0001). In conclusion, IVIM is sensitive in detecting bone marrow ischemia in a piglet model of LCPD.This article is protected by copyright. All rights reserved.