Florian Wiesinger¹, Sandeep Kaushik², Anne Menini¹, Sangtae Ahn³, Lishui Cheng³, Cristina Cozzini¹, Thomas Hope⁴, Jaewon Yang⁴, Peder Larson⁴, and Dattesh Shanbhag^2
1GE Global Research, Munich, Germany, ²GE Global Research, Bangalore, India, ³GE Global Research, Schenectady, NY, United States, ⁴University of California San Francisco, San Francisco, CA, United States

Recently we presented a method for zero TE MR bone imaging in the head.  In this abstract, we describe the extension of this work towards whole body skeletal imaging as required for applications like PET/MR Attenuation Correction, or MR-based Radiation Therapy Planning.

Mary Kate Manhard¹, Kevin D Harkins², Daniel F Gochberg², Jeffry S Nyman³, and Mark D Does^1
1Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, ²Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States, ³Department of Orthopaedics & Rehabilitation, Vanderbilt University, Nashville, TN, United States

Imaging bound and pore water concentrations in cortical bone using UTE MRI has shown potential for evaluating fracture risk, but 3D methods require a relatively long scan time (~30 minutes total). 2D UTE with optimized half-pulses was implemented to acquire both bound and pore water maps in ~30 seconds and results were compared to 3D UTE, both ex vivo and in vivo. Mean differences in bound/pore water concentration were less than 10%. Applying these fast sequences in 2D has the potential to greatly increase the utility of these methods in clinical settings for evaluating fracture risk in patient populations.

Maximilian Nikolaus Diefenbach¹, Anh T. Van², Jakob Meineke³, Hendrik Kooijman⁴, Axel Haase², Ernst J. Rummeny⁵, Jan S. Kirschke⁶, Thomas Baum¹, and Dimitrios C. Karampinos^5
1Department of Diagnostic and Interventional Radiology, Technische Univeristät München, Munich, Germany, ²Zentralinstitut fu¨r Medizintechnik, Technische Universita¨t Mu¨nchen, Munich, Germany, ³Philips Research Laboratory, Hamburg, Germany, ⁴Philips Healthcare, Hamburg, Germany, ⁵Department of Diagnostic and Interventional Radiology, Technische Universität München, Munich, Germany, ⁶Section of Neuroradiology, Technische Universität München, Munich, Germany

Trabecular bone imaging has a high clinical significance for predicting fracture risk in patients with osteoporosis. Quantitative susceptibility mapping (QSM) has been recently emerging for mapping diamagnetic and paramagnetic substances.  Recent reports attempted to use QSM combined with ultra-short echo time imaging for mapping the susceptibility of cortical bone. However, it remains unknown whether QSM is feasible for measuring bone volume density in trabecular bone, where the bone density is much lower than cortical bone. The purpose of the present work is to study the feasibility of QSM for trabecular bone density mapping, using numerical simulations, specimen measurements and preliminary in vivo measurements.

Roland Krug¹, Andrew Lai¹, Lorenzo Nardo¹, Luca Facchetti¹, Misung Han¹, Galateia Kazakia¹, and Julio Carballido-Gamio^1
1University of California, UCSF, San Francisco, CA, United States

MRI is currently the only modality to assess trabecular bone structure with high-resolution in the proximal femur in-vivo. We have optimized image acquisition and image analysis techniques to assess microstructural bone parameters in HIV-infected individuals compared to healthy controls. We have found significant differences in the femoral head, neck and trochanteric regions between patients and controls. We conclude that MRI can be an important tool to assess bone structure in the central skeleton at important fracture sites such as the proximal femur with very high resolution. 

Mathilde Granke¹, Kuniko Hunter², Sasidhar Uppuganti¹, Jeffry S Nyman^1,3, and Mark D Does^1
1Vanderbilt University, Nashville, TN, United States, ²Rensselaer Polytechnic Institute, Troy, NY, United States, ³VA Tennessee Valley Healthcare System, Nashville, TN, United States

¹H NMR- derived bound water measurements in cadaveric human trabecular bone are sensitive to age-related changes in the quality of bone tissue, and therefore could be predictive of fracture risk in trabecular sites prone to fracture.  

Jun Chen¹, Michael Carl², Hongda Shao¹, Eric Chang¹, Graeme Bydder¹, and Jiang Du^1
1Radiology, University of California, San Diego, San Diego, CA, United States, ²GE Healthcare, San Diego, CA, United States

Bone water exists in the form of free water in the Haversian canals or lacunar-canalicular system, as well as bound water either loosely bound to collagen or more tightly bound to mineral. Ultrashort echo time (UTE) sequences with TEs as short as 8 µs can potentially detect signal from pore water and loosely bound water. In this study, we introduce an approach for fast volumetric mapping of bound and pore water content in vivo using a clinical 3T MR scanner.

Chuan Huang^1,2, Anuradha Janardhanan^1,3, and Mark Schweitzer^1
1Radiology, Stony Brook Medicine, Stony Brook, NY, United States, ²Psychiatry, Stony Brook Medicine, Stony Brook, NY, United States, ³Diagnostic Imaging, Kuala Lumpur Hospital, Kuala Lumpur, Malaysia

Understanding the distribution of red marrow is important for various hematopoetic diseases and especially osseous metastases as areas of red marrow are the primary sites for hematogenous seeding of tumor cells, accounting for approximately 90% of skeletal metastases. Using a simultaneous PET-MR we sought to evaluate voxel of red marrow in the femora and pelvis using fat/water sequences correlated with FDG PET uptake. This quantitative assessment of red and yellow marrow was done in specific anatomic subregions.  The bone marrow composition and metabolism were found to be symmetric in each individual. Good correlation between SUV and %red were found for each ROI among all subjects. The metabolism (FDG uptake) was found to be different for the ROIs with the same amount of red marrow. Further research will study whether this leads to higher chance of tumor seeding.

Inbar Hillel¹, Yifat Sarda¹, Elad Bergman¹, Itzhak Binderman², and Uri Nevo^1
1Department of Biomedical Engineering, Tel-Aviv University, Tel Aviv, Israel, ²School of Dental Medicine, Tel-Aviv University, Tel Aviv, Israel

Osteoporosis is a disease characterized by loss of bone mineral density, caused by loss of the equilibrium between osteogenesis and adipogenesis. In this work T2, T1 and ADC were measured using a low-field NMR scanner, for the detection of bone marrow changes related to osteoporosis. Results showed that this method is capable of significantly classifying between bones of rats that were ovariectomized, ovariectomized and treated with parathyroid hormone, and sham-operated rats.

Uchechukwuka Monu¹, Feliks Kogan², Emily McWalter², Brian Hargreaves², and Garry Gold^2
1Electrical Engineering, Stanford University, Stanford, CA, United States, ²Radiology, Stanford University, Stanford, CA, United States

New PET/MR systems have made the simultaneous acquisition and quantitative assessment of bone and cartilage possible. Using projection maps and cluster analysis, the comprehensive visualization and quantification of PET ¹⁸F-NaF uptake within an injured and contralateral knee are determined and compared with corresponding T2 and T1rho relaxation times within the cartilage. Significant increase in PET uptake is observed in the injured knee compared to the contralateral knee and some areas of high PET uptake correspond with elevated T2 and T1rho relaxation times. This developed tool shows promise in assessing bone metabolic activity and its relationship with quantitative MR parameters.

Chamith S. Rajapakse¹, Benjamin T. Newman¹, Wenli Sun¹, Michael Ispiryan¹, Michelle Slinger², Elizabeth A. Kobe², Kelly Borges¹, Karyll Davis², Keren De Jesus², Jeremy Magland¹, and Felix W. Wehrli^1
1Laboratory for Structural NMR Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States, ²University of Pennsylvania School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, United States

High-resolution MRI-derived finite element analysis allows for the in vivo estimation of bone strength. This information is useful for planning treatments and interventions in individuals suffering from conditions that affect bone mineral homeostasis. However these methods have not been previously validated. This study subjected distal tibia specimens to both MRI-based finite element analysis and mechanical testing ex vivo. Estimated bone stiffness was strongly correlated to the experimental values (R2=0.84) supporting usefulness of MRI-based bone strength assessment in human subjects.