Advanced Orthopaedic Imaging at the Medical College of Wisconsin

NIH: Enabling Diffusion-Weighted MRI Near Metallic Implants
(Project Lead: Kevin Koch, PhD)
In this project, we pursued an aggressive technical development project focused on enabling clinically viable diffusion-weighted magnetic resonance imaging (MRI) in the near vicinity of metallic hardware. Based on promising preliminary investigations of diffusion-weighted multi-spectral MRI, a selection of technical extensions and alternatives were proposed for exploration and comparative testing. The results of these development efforts have opened diffusion-weighted MRI to clinicians seeking assessments of conditions such as cancer, infection, necrosis, spinal cord damage, and nerve impingement near metal implants.

Department of Defense: Quantitative MRI of the Post-Injury Instrumented Spinal Cord
(Project Lead, Kevin Koch, PhD)
In this study, we propose to solve the metal artifact problem in quantitative MRI of the spinal cord by tailoring the aforementioned advanced MRI metal artifact reduction strategies to enable quantitative analysis of the spinal cord. A multidisciplinary team of surgeons, spinal cord scientists, and physicists will then deploy these methods to injured, degenerated, and control cohorts. In particular, we hypothesize that morphological and diffusion-weighted MRI will provide useful quantitative imaging biomarkers for assessment of treatment effectiveness and recovery progress.

NIH: Enabling Kinematic Joint Profiling Using MRI
(Project Lead, Kevin Koch, PhD)
We seek to develop and demonstrate fundamental methods in quantitative kinematic profiling using clinical diagnostic imaging equipment. This technical development project is constructed under the hypothesis that such profiling of moving joints can highlight dysfunction, treatment progress, and point towards favorable (or unfavorable) surgical interventions. Using currently available advanced magnetic resonance imaging technology, data collected from a controlled subject cohort will be used to develop and test the proposed kinematic profiling technology on the moving wrist.

NIH: Th Ability of MRI to Detect Adverse Local Tissue Reaction And Implant Integration As A Function Of Hip Implant Modularity
(Project Lead, Matthew Koff, PhD and Hollis Potter, MD, Hospital for Special Surgery, NYC, NY)
This project seeks to continue previous investigations whereby total joint replacement specialists at the Hospital for Special Surgery are evaluating causes of total hip replacement failure. Dr. Koch’s team at MCW is assisting in this project by providing advanced quantitative MRI technology for assessments near total hip replacements. In the past several years, Dr. Koch’s lab has developed quantitative tissue metallosis measurement tools and a mechanism for T2 relaxometry mapping near total hip replacements. Currently, these tools are being utilized by the HSS team in their quantitative analysis of hip replacements.

Industry collaborations: Our research group is currently funded for orthopaedic technical development projects by GE Healthcare and Siemens Healthcare. These projects are focused on exploring new mechanisms to improve orthopaedic MRI image acquisition and interpretation.

Clinical evaluation of lumbar foraminal stenosis typically includes qualitative assessments of perineural epidural fat content around the spinal nerve root and evaluation of nerve root impingement. The present study investigates the use of several morphological MRI-derived metrics as quantitative predictors of foraminal stenosis grade. Read Dr. Gunasekaran's article "Quantitative correlation of lumbar foraminal stenosis with local morphological metrics."

Diffusion-weighted imaging has undergone substantial investigation as a potential tool for advanced assessment of spinal cord health. Unfortunately, commonly encountered surgically implanted spinal hardware has historically disrupted these studies. This preliminary investigation applies the recently developed multispectral diffusion-weighted PROPELLER technique to quantitative assessment of the spinal cord immediately adjacent to metallic spinal fusion instrumentation. Read Dr. Koch’s article "Multispectral diffusion-weighted MRI of the instrumented cervical spinal cord: a preliminary study of 5 cases."

The failure of total hip arthroplasty (THA) is commonly associated with the necrosis of the periprosthetic tissue. To date, there is no established method to noninvasively quantify the progression of such necrosis. Magnetic resonance imaging (MRI) of soft tissues near implants has undergone a recent renaissance due to the development of multispectral metal-artifact reduction techniques. Advanced analysis of multispectral MRI has been shown capable of detecting small magnetism effects of metallic debris in periprosthetic tissue. The purpose of this study is to demonstrate the diagnostic utility of these MRI-based tissue-magnetism signatures.

Read more of Dr. Koch’s article "Multivariate use of MRI biomarkers to classify histologically confirmed necrosis in symptomatic total hip arthroplasty."

Due to host-mediated adverse reaction to metallic debris, there is an increasing need for noninvasive assessment of the soft tissue surrounding large joint arthroplasties. Quantitative T₂ mapping can be beneficial for tissue characterization and early diagnosis of tissue pathology but current T₂ mapping techniques lack the capability to image near metal hardware. A novel multi-spectral T₂ mapping technique is proposed to address this unmet need. Read more of Dr. Koch’s article "3D-multi-spectral T ₂ mapping near metal implants."

The presence of metallic debris near total hip arthroplasty can have a significant impact on longitudinal patient management. Methods for magnetic resonance imaging-based quantification of metallic debris near painful total hip replacements are described and applied to cohorts of symptomatic and control subject cases. Read more of Dr. Koch’s article "Off-resonance based assessment of metallic wear debris near total hip arthroplasty."

The need for diffusion‐weighted‐imaging (DWI) near metallic implants is becoming increasingly relevant for a variety of clinical diagnostic applications. Conventional DWI methods are significantly hindered by metal‐induced image artifacts. A novel approach relying on multispectral susceptibility artifact reduction techniques is presented to address this unmet need. Read more of Dr. Koch’s article "Multispectral diffusion‐weighted imaging near metal implants."