Quantitative Methods in Musculoskeletal Tissues

Tuesday 13 May 2014

Jari Rautiainen^1,2, Elli-Noora Salo³, Virpi Tiitu⁴, Mikko A.J. Finnilä⁵, Olli-Matti Aho⁶, Simo Saarakkala^3,5, Petri Lehenkari⁶, Jutta Ellermann⁷, Mikko J. Nissi^7,8, and Miika T. Nieminen^2,3
1Department of Applied Physics, University of Eastern Finland, Kuopio, Eastern Finland, Finland, ²Department of Diagnostic Radiology, University of Oulu, Oulu, Northern Finland, Finland, ³Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Northern Finland, Finland, ⁴Institute of Biomedicine, Anatomy, University of Eastern Finland, Kuopio, Eastern Finland, Finland, ⁵Department of Medical Technology, University of Oulu, Oulu, Northern Finland, Finland, ⁶Department of Anatomy and Cell Biology, University of Oulu, Oulu, Northern Finland, Finland, ⁷Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, MN, United States, ⁸Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN, United States

The purpose of this study was to evaluate sensitivity of quantitative MRI techniques for assessment of human tibial articular cartilage with varying degrees of degeneration. For reference, biomechanical measurements, quantitative histology and OARSI grading were performed. The MRI techniques were able to differentiate early osteoarthritis and advanced osteoarthritis specimens and the measures were highly correlated with the biomechanical parameters as well as OARSI grade. Rotating frame MRI techniques (adiabatic T1ρ, adiabatic T2ρ, CW-T1ρ and RAFF) were the most sensitive methods to detect cartilage degeneration.

Richard G. Spencer¹, Vanessa A. Lukas¹, Benjamin D. Cortese², David A. Reiter¹, Kenneth W. Fishbein¹, Nancy Pleshko³, and Bimal Sinha^4
1Magnetic Resonance Imaging and Spectroscopy Section, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States,²Department of Mathematics, Syracuse University, Syracuse, New York, United States, ³Tissue Imaging and Spectroscopy Laboratory, Bioengineering Department, Temple University, Philadelphia, Pennsylvania, United States, ⁴Department of Mathematics and Statistics, University of Maryland, Baltimore County, Baltimore, Maryland, United States

Little work has been done to translate cartilage-sensitive MR outcome measures to clinical decision rules. The goal of this investigation is to develop and apply clinical classification rules based on group differences between cartilage-matrix sensitive MR measurements. We develop two distinct methods, one based on the Euclidean distance metric and one based on the likelihood ratio approach. We derive closed-form expressions for the sensitivity and specificity these decision rules, and present analyses of both a cartilage degradation dataset and literature results. We find that even highly statistically significant group differences may not lead to high-quality clinical decision rules.

Stephen J. Matzat¹, Emily J. McWalter¹, Feliks Kogan¹, Weitian Chen², and Garry E. Gold^1,3
1Radiology, Stanford University, Stanford, CA, United States, ²MR Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States,³Bioengineering, Stanford University, Stanford, CA, United States

New MR pulse sequences provide faster methods for T₂ mapping of articular cartilage, yet each method may introduce a bias in T₂ quantitation. The present study analyzes quantitative outcomes from six MR sequences for in vivo T₂ mapping of patellar, femoral, and tibial cartilage, using single echo spin echo as a reference standard. Some sequences exhibited a consistent bias in T₂ measurements while others demonstrated varied bias along the range of T₂ values. Overall variation between sequences was appreciable and highlights the importance of further study of these differences.

Fang Liu¹, Alexey Samsonov¹, Pouria Mossahebi², Rajeev Chaudhary², Wally Block^1,2, and Richard Kijowski^3
1Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, United States, ²Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States, ³Department of Radiology, University of Wisconsin-Madison, Wisconsin, United States

A new technique named multi-component Relaxation Imaging using Steady-state signal Evolution (mcRISE) was proposed in this study to resolve unbiased and magnetization transfer (MT) corrected multi-component T2 measures. Our technique introduces a macromolecular proton pool in exchange with regular two component water pools and uses a combined model aimed for providing more robust and unbiased multi-component T2 values along with additional quantitative MT parameters, which may provide a new set of biomarkers for assessing the cartilage extracellular matrix in-vivo.

Ping Wang^1,2 and John C Gore^1,2
1Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, United States, ²Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, United States

T₁rho variations with spin-locking strength (= the T₁rho dispersion) can provide a more complete characterization of tissue composition and the physicochemical changes associated with pathology. In this work, in vivo R₁rho (=1/T₁rho) dispersion of human knee cartilage (articular and epiphyseal) was studied at 3T. Our data show pronounced R₁rho dispersion over practical locking fields; the mean exchange rate was measured at ~992 Hz when fitting the data to the Chopra model. To the best of our knowledge, this is the first R₁rho dispersion measurement in human articular/epiphyseal cartilage, and forms the basis for more quantitative evaluation of cartilage disorders.

Ravi Prakash Reddy Nanga¹, Anup Singh¹, Hari Hariharan¹, and Ravinder Reddy^1
1Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States

Since gag-CEST is promising at 7T for imaging knee cartilage, we have evaluated the pH sensitivity of gagCEST on 5% chondrotin sulfate phantoms with varying pH from 4-8 at both room temperature as well as at 37 °C as there are emerging reports of a pH drop in the knee cartilage of osteoarthritis subjects.

Ashley A Williams¹ and Constance R Chu^1
1Department of Orthopedic Surgery, Stanford University, Stanford, CA, United States

This study examines the range of echo times (TEs) required to detect significant T2* differences in cartilage and meniscus between two clinically distinct cohorts: ACL-injured subjects without arthroscopic evidence of damage to medial femoral cartilage or medial meniscus, and uninjured controls. Reanalysis of MRI data from previously reported studies suggests that while UTE (TE<1ms) was not strictly required to detect differences between these two cohorts, inclusion of UTE (0.6ms) acquisitions augmented the ability of T2* calculation to discriminate between the cohorts, particularly in deep articular cartilage.

Won C Bae¹, Karen Chen^2,3, Graeme M Bydder¹, and Christine B Chung^2,3
1Department of Radiology, University of California, San Diego, San Diego, CA, United States, ²VA San Diego Healthcare System, San Diego, United States, ³University of California, San Diego, San Diego, United States

Cartilaginous endplate (CEP) deficiency has been cited as a cause of vertebral endplate (VEP) lesions. UTE MRI, which enables direct evaluation of CEP morphology, was used to evaluate lumbar spines with and without VEP lesions. CEP overlying normal VEP were generally normal, while CEP overlying VEP lesions were abnormal. Agreement between observers was substantial. UTE MRI of the CEP may be useful for better understanding of CEP pathology, and etiology of VEP lesions.

Matthew F. Koff¹, Sarah Pownder¹, Wei Yang Lim¹, Parina Shah¹, and Hollis G. Potter^1
1Department of Radiology and Imaging - MRI, Hospital for Special Surgery, New York, NY, United States

Tendon visualization using standard MR sequences is difficult due to limited signal intensity. UTE sequences display contrast within a tendon, and allow for T2* calculation. This study determined the effects of a freeze-thaw cycle and cyclic loading on tendon T2* values. No difference of T2* was found between the fresh and frozen samples, and shorter T2* values were found after loading. Reduction of T2* is due to greater tissue organization from the uncrimping of collagen fibrils. The relationship between T2* and applied load has clinical implications for assessment of ligament reconstruction and tendon repair.

Delphine Perie^1,2, Simon-Pierre Coté^1,2, Guillaume Gilbert³, Maxime Raison^1,2, and Guy Grimard^2
1Mechanical Engineering, Ecole Polytechnique de Montréal, Montreal, QC, Canada, ²Research Center, CHU Sainte Justine, Montreal, QC, Canada, ³Philips Health Care, Montreal, QC, Canada

While the diagnosis and treatment of a ruptured ACL have been under heavy study for the last decades, the postoperative evaluation is still performed using qualitative methods. Eight healthy volunteers had their left knee imaged using multi-parametric MRI in two positions: in full extension with the ACL under heavy tension, and at 20 degrees of flexion with the ACL nearly at rest. There were significant differences between knee positions for T1rho and T2*, and between subjects for T1rho only. To our knowledge, this study represents the first attempt to assess directly in vivo the tension state of the ACL. T1rho seems to be a good indicator of the tension state within the ACL.