Ultrashort Time-To-Echo MRI of Human Intervertebral Disc Endplate: Association with Disc Degeneration
Won C. Bae¹, Tomoaki Yoshikawa², Richard Znamirowski¹, Aseem R. Hemmad², Bruno C. Vande Berg³, Christine B. Chung¹, Koichi Masuda², Graeme M. Bydder^1
1Radiology, University of California, San Diego, San Diego, CA, United States; ²Orthopaedic Surgery, University of California, San Diego, San Diego, CA, United States; ³Radiology, Cliniques Universitaires St Luc, Université Catholique de Louvain, Brussels, Belgium

UTE MR image of human lumbar spine reveals distinct linear signal near disc endplates, unlike signal voids seen in conventional MR images. Normal and abnormal (loss and diminution) patterns of UTE signal were evaluated in 29 lumbar spines at different levels. In addition, disc degeneration was evaluated in T2-weighted spin echo images using Pfirrmann grading system. UTE signal abnormality did not depend on the level, but was increasingly found in levels with advanced disc degeneration. The present results demonstrated unique ability of UTE MRI to directly evaluate region near endplate, and association between endplate MR changes with disc degeneration.

Quantitative Comparison of T1ρ with T2 in Intervertebral Disc in Vivo at 3T - not available
Queenie Chan^1,2, Mina Kim², Marina-Portia Anthony², Kenneth MC Cheung³, Aaron Chan², Tao Chan², Pek-Lan Khong^2
1Philips Healthcare, Hong Kong, China; ²Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong, China; ³Division of Spine Surgery, Department of Orthopaedics and Traumatology, Faculty of Medicine, The University of Hong Kong, Hong Kong, China

Diagnostic techniques based on conventional T2-weighted images are commonly used for disc degeneration but are subjective and not sensitive to subtle changes in the intervertebral discs (IVDs). Therefore, quantitative assessment would play an important role in greatly improving the evaluation of disc degeneration. In this study, we performed quantitative T1ρ and T2 measurements in human lumbar IVDs. Our results suggest that different degenerative-related changes taking place in between the central nucleus pulposus and the outer annulus fibrosus can be quantitatively assessed using T1ρ and T2 mapping which may provide complementary information to better understand pathophysiological mechanisms in disc degeneration.

T1ρ MRI and Discography Opening Pressure Are Quantitative Biomarkers of Disc Degeneration in Vivo
Matthew Fenty¹, Chenyang Wang¹, Walter RT Witschey¹, Rachelle Berger¹, Philip Maurer², Dawn M. Elliott³, Ravinder Reddy¹, Ari Borthakur^1
1CMROI, Department of Radiology, University of Pennsylvania School of Medicine, Philadelphia, PA, United States; ²3B Orthopaedics, Philadelphia, PA, United States; ³Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia, PA, United States

The objective of this study is to evaluate T1ρ MRI as quantitative biomarker of disc degeneration in patients being treated for Lower Back Pain (LBP) by comparing it to invasive discography opening pressure.  A significant and strong correlation exists between non-invasive MRI T1ρ values and in vivo opening pressure measurements. T1ρ is a quantitative measure of degeneration that is consistent across both control subjects and LBP patients.

Short Time T2 Variability of the Lumbar Intervertebral Disc – in Vivo MRI Study at 3 Tesla
David Stelzeneder¹, Sabine Goed¹, Götz Hannes Welsch^1,2, Clemens Hirschfeld¹, Tatjana Paternostro-Sluga³, Karin Pieber³, Klaus Friedrich¹, Michael Reisegger¹, Tallal Charles Mamisch⁴, Siegfried Trattnig^1
1Department of Radiology, MR Centre, Medical University of Vienna, Vienna, Austria; ²Department of Trauma Surgery, University of Erlangen, Erlangen, Germany; ³Department of Physical Medicine and Rehabilitation, Medical University of Vienna, Vienna, Austria; ⁴Department of Orthopedic Surgery, University of Bern, Inselspital, Bern, Switzerland

The purpose of our study was to evaluate the short-time variability of T2 relaxation time values in the supine position in different compartments of the lumbar intervertebral disc. We performed a segmental analysis of two serial T2 mapping sequences obtained with a delay of 40 minutes. There was a significant T2 decrease in the anterior nucleus and an increase in the posterior annulus region. The data can be interpreted as a water shift from the anterior to the posterior compartments of the intervertebral disc, what can be a result of supine position with slight hip flexion.

Quantitative Evaluation of Diffusion Tensor Imaging at 3T in Human Lumbar Intervertebral Disc Degeneration - not available
Queenie Chan^1,2, Marina-Portia Anthony², Zhongping Zhang², Kenneth MC Cheung³, Mina Kim^2
1Philips Healthcare, Hong Kong, China; ²Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong, China; ³Division of Spine Surgery, Department of Orthopaedics and Traumatology, Faculty of Medicine, The University of Hong Kong, Hong Kong, China

Detecting early stages of disc degeneration is a major challenge in degenerative disc disease (DDD) as current diagnostic techniques are not sensitive or completely objective. Therefore, a quantitative assessment of disc degeneration would significantly improve the evaluation of DDD. In this study, we examined diffusion tensor imaging (DTI) in human lumbar intervertebral discs (IVDs) to investigate changes in tissue microstructure. Our results show that fractional anisotropy can quantitatively assess 1) structural difference between a nucleus pulposus and an annulus fibrosus and 2) degenerative changes in IVDs, suggesting DTI may be a potential biomarker for DDD.

Assessment of Glycosaminoglycan Distribution in Human Lumbar Intervertebral Discs Using Chemical Exchange Saturation Transfer - not available
Mina Kim¹, Queenie Chan², Marina-Portia Anthony¹, Kenneth MC Cheung³, Dino Samartzis³, Tao Chan¹, Pek-Lan Khong^1
1Department of Diagnostic Radiology, The University of Hong Kong, Pokfulam, Hong Kong, China; ²Philips Healthcare, Hong Kong; ³Division of Spine Surgery, Department of Orthopaedics and Traumatology, The University of Hong Kong, Hong Kong

Detecting early disc degeneration is of vital importance in order to identify subjects that are suitable for treatment. However, current diagnostic techniques are not sensitive to the early stages of intervertebral disc (IVD) degeneration, which involves the loss of proteoglycans. Recently, it has been suggested that glycosaminoglycan content can be quantified by chemical exchange saturation transfer (gagCEST). In the present work, we conducted gagCEST imaging for IVDs of human volunteers. Our results show that in vivo gagCEST quantification is feasible at 3 Tesla and may potentially be a useful clinical tool in identifying early degenerative changes in the human IVDs.

Ultra-Short Echo-Time (UTE) Imaging Based Estimation of Cortical Bone Stiffness
Chamith S. Rajapakse¹, Hamidreza Saligheh Rad¹, Shing Chun Benny Lam¹, James Love¹, Jeremy F. Magland¹, Felix W. Wehrli^1
1University of Pennsylvania School of Medicine, Philadelphia, PA, United States

It is well known that intracortical remodeling occurs resulting in increased porosity with advancing age and impaired strength. UTE MRI now offers the potential to estimate true bone tissue fraction as 1-BWF where BWF is bone water fraction. Here, we investigated the feasibility of estimating cortical bone stiffness in healthy volunteers using micro-finite-element analysis on the basis of BWF maps derived from UTE imaging. The preliminary results suggest that the incorporation of BWF to the FE analysis can enhance the assessment of mechanical competence of cortical bone in vivo compared to the mechanical and structural measures derived from conventional imaging.

Correlation of ¹H NMR Characteristics and Mechanical Properties in Human Cortical Bone
R. Adam Horch^1,2, Jeffery S. Nyman^3,4, Dan F. Gochberg^1,5, Mark D. Does^1,2
1Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States; ²Biomedical Engineering, Vanderbilt University, Nashville, TN, United States; ³VA Tennessee Valley Healthcare System, Vanderbilt University, Nashville, TN, United States; ⁴Orthopaedics & Rehabilitation Medicine, Vanderbilt University, Nashville, TN, United States; ⁵Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN, United States

The complex ¹H NMR behavior of human cortical bone can be attributed to distinct microanatomical proton environments in the bone matrix and pore spaces. Herein, the multiexponential ¹H transverse relaxation of human cortical bone was studied in conjunction with numerous mechanical properties relevant to overall bone integrity. Numerous NMR-mechanical correlations were observed, indicating links between cortical bone proton pools and bone health. These correlations allow bone mechanical properties to be predicted from NMR measurements and provide a contrast mechanism that MRI protocols could exploit as a novel bone health diagnostic.

Bone Water Concentration as a New Metric for Cortical Bone Quality
Hamidreza Saligheh Rad¹, James Love¹, Jeremy F. Magland¹, Mary F. Leonard², Felix W. Wehrli^1
1Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania Health System, Philadelphia, PA, United States; ²Nephrology, Children's Hospital of Philadelphia, Philadelphia, PA, United States

Increased porosity is a major cause of impaired strength of cortical bone. Ultra-short TE MRI has been shown to be able to quantify bone water, which is either collagen-bound or residing in the pores of the Haversian and lacuno-canalicular system. In this preliminary work we compare bone water concentration (BWC) in the tibial mid-shaft in a group of subjects with 3D bone mineral density (BMD) at the same location as well as areal BMD at the hip and spine. BWC is found to be inversely related to BMD at all sites and increasing with age.

SWIFT Versus X-Ray in Dental Imaging
Djaudat Idiyatullin¹, Curt Corum¹, Steen Moeller¹, Hari S. Prasad², Michael Garwood¹, Donald R. Nixdorf^3
1CMRR, University of Minnesota, Minneapolis, MN, United States; ²Division of Oral Pathology in the Department of Diagnostic & Biological Sciences, University of Minnesota, Minneapolis, MN, United States; ³Division of TMD & Orofacial Pain and Department of Neurology, University of Minnesota, Minneapolis, MN, United States

A comprehensive comparison of the traditional X-ray imaging modality versus to a novel magnetic resonance imaging (MRI) technique, called SWeep Imaging with Fourier Transform (SWIFT) in dental application (in-vitro) is presented. It is shown that the distinctive feature of SWIFT images is the visualization of the morphology of densely mineralized enamel and dentin simultaneous with dental caries and neurovascular architecture in the pulp. Additionally, fine structures that are normally difficult to detect with radiographs, such as cracks within the tooth and accessory canals can be identified in scanning time relevant for in-vivo applications. All conclusions supported with histology of teeth.