Assessment of Osteonecrosis in the Presence of Instrumentation for Femoral Neck Fracture Using Contrast-Enhanced MAVRIC Sequence

Abstract

Background: Evaluating postoperative femoral neck facture (FNF) with metal fixation hardware is commonly performed using radiographs. MRI has greater sensitivity and specificity to evaluate osteonecrosis (ON) but is often challenging due to the image distortion caused by metallic hardware. Questions/Purposes: The aim of this study is to compare fast spin-echo (FSE) and multiacquisition variable-resonance image combination (MAVRIC) sequences in assessing ON following metallic fixation of FNF and determining feasibility of semiquantitative perfusion using MAVRIC. Methods: Radiography and MRI were performed at 3 and 12 months postoperatively, using FSE and pre-and post-gadolinium contrast MAVRIC sequences in 21 FNF patients. The presence and volume of ON were recorded. Signal intensity (SI) enhancement was measured on the MAVRIC sequences within the center and rim of ON; with the ilium and femoral diaphysis as controls. The detection rate of ON between MAVRIC and FSE images was evaluated as the difference of percent enhancement across the defined regions of interest. Results: ON was detected in 0% of radiographs, in 67% of FSE, and in 76% of MAVRIC images at 3 months follow-up, with similar results at 12 months. MAVRIC images had larger ON volume than FSE images at both time points. A significant percentage SI enhancement was only detected in the ON rim. Conclusion: Radiographs could not detect ON following metallic fixation of FNF. MAVRIC is more sensitive than FSE for determining the volume of ON. SI measurements using MAVRIC may provide an indirect assessment of perfusion.

Improved Visualization of Juxtaprosthetic Tissue Using Metal Artifact Reduction Magnetic Resonance Imaging

“…21 New specialized MARS techniques include VAT, multiacquisition variable-resonance image combination, and SEMAC. 3,[5][6][7]9,[22][23][24][25][26][27][28][29][30][31][32][33] They allow a more accurate diagnosis with implications on treatment strategies. SEMAC reduces through-plane distortions via pseudo-3D acquisitions.…”

Advances in MRI around metal

“…) . MAVRIC has been shown to be more sensitive than standard TSE sequences for determining the volume of osteonecrosis of the femoral head in patients with instrumentations for femoral neck fractures . But most reports on the utility of MARS imaging are on hip prostheses, since total hip arthroplasty (THA) is the most commonly performed prosthesis implantation .…”

Morphologic and quantitative magnetic resonance imaging of knee articular cartilage for the assessment of post‐traumatic osteoarthritis

“…Newer multi‐spectral imaging (MSI) techniques such as Multi‐Acquisition Variable Image Resonance Combination (MAVRIC) and Slice Encoding for Metal Artifact Correlation (SEMAC), and associated hybrids minimize the distortions . These techniques permit direct visualization of articular surfaces, even when stainless steel fixation hardware, which has extremely high magnetic susceptibility, is located near the articular surface . Even with these limitations, appropriate protocols exist to perform morphologic and quantitative analysis of articular knee cartilage in clinically feasible scan times.…”