Alexey V. Dimov^1,2, Zhe Liu^1,2, Pascal Spincemaille², and Yi Wang^1,2
1Department of Biomedical Engineering, Cornell University, Ithaca, NY, United States, ²Radiology Department, Weill Cornell Medical College, New York, NY, United States

Bone quantitative susceptibility mapping (QSM) using standard IDEAL fat water/signal model often suffers from erroneous labeling of water component. We propose a new field estimation approach incorporating the negligible T2* decay of fat compared to bone water signal, and modeling fat with multiple spectral peaks. This tissue specific R2* multi-peak signal allows robust field mapping from radial ultra-short TE gradient echo data, enabling in vivo bone QSM with consistent high quality.

Markus Matthias Schreiner^1,2, Stefan Zbyn², Benjamin Schmitt³, Stephan Domayer¹, Reinhard Windhager¹, Siegfried Trattnig², and Vladimir Mlynarik^2
1Department of Orthopaedic Surgery, Medical University of Vienna, Vienna, Austria, ²Department of Biomedical Imaging and Imag-Guided Therapy, High Field MR Centre, Medical University of Vienna, Vienna, Austria, ³Siemens Healthcare Pty Ltd, Macquarie Park, Australia

Early onset osteoarthritis is associated with ultrastructural and compositional changes of cartilage, in particular with a loss of glycosaminoglycans (GAGs) and disorganization of the collagen matrix. Both changes remain elusive to morphological MRI. GagCEST is a promising tool for the evaluation of glycosaminoglycan content in articular cartilage. However, it is affected by many variables, thus rendering its application challenging. The implementation of a novel saturation scheme combined with optimized fixation seems to improve the robustness of the technique as indicated by increased reproducibility. Our optimized protocol seems to be sensitive to regional differences in the GAG content.

Andreas Boss¹, Linda Heskamp¹, Mark Jacobus van Uden¹, Lauren Jean Bains^2,3, Vincent Breukels¹, and Arend Heerschap^1
1Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, Netherlands, ²Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, Netherlands,³Donders Centre for Cognitive Neuroimaging, Radboud University, Nijmegen, Netherlands

Traditional PCr recovery experiments are performed in a non-localized way, while skeletal muscle is not homogeneous. In this study we performed localized ³¹P-MRS using a ladder-shaped ³¹P-phased array receive coil optimized for the tibialis anterior and found a pronounced variation in the rate of PCr recovery after isometric exercise along the length of this muscle in healthy volunteers. In addition, we observed similar regional differences in the time-to-peak signal intensity of muscle functional MRI obtained after exercise in the same volunteers. The reasons for this strong functional gradient along the tibialis anterior remain, however, to be elucidated.

Abdul Wahed Kajabi^1,2,3, Victor Casula^2,3, Arttu Peuna^2,3,4, Simo Saarakkala^2,5, Eveliina Lammentausta^3,4, Ali Guermazi⁶, and Miika T. Nieminen^2,3,4
1Department of Biomedical Engineering, University of Oulu, Oulu, Finland, ²Research Unit of Medical Imaging, Physics and Technology, University of Oulu and Oulu University Hospital, Oulu, Finland,³Medical Research Center, University of Oulu and Oulu University Hospital, Oulu, Finland, ⁴Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland, ⁵Department of Medical Technology, Institute of Biomedicine, University of Oulu, Oulu, Finland, ⁶Department of Radiology, Boston University School of Medicine, MA, MA, United States

Evaluation of meniscal degeneration in asymptomatic subjects and patients with early osteoarthritis (KL = 1,2) was performed using adiabatic $$$T_{1\rho}$$$ and $$$T_{2\rho}$$$ ($$$AdT_{1\rho}$$$ and $$$AdT_{2\rho}$$$, respectively) measurements in sagittal plane. Menisci of all subjects were also evaluated using semiquantitative MRI OA Knee Score (MOAKS). The results show that the length of $$$AdT_{1\rho}$$$ and $$$AdT_{2\rho}$$$ is directly related to clinical symptoms and the severity of meniscal degeneration. $$$AdT_{1\rho}$$$ and $$$AdT_{2\rho}$$$ may provide a non-invasive means of detecting and monitoring degenerative changes in the meniscus.

Xiang He¹, Kenneth Wengler², Alex C Sacher³, Marco Antonio Oriundo Verastegui¹, Alyssa Simeone⁴, Mingqian Huang¹, Elaine Gould¹, and Mark Schweitzer^1
1Department of Radiology, Stonybrook University School of Medicine, Stony Brook, NY, United States, ²Department of Biomedical Engineering, Stonybrook University School of Medicine, Stony Brook, NY, United States, ³SUNY Binghamton University, Binghamton, NY, United States, ⁴New York Medical College, Valhalla, NY, United States

Diffusion tensor imaging (DTI) is sensitive to the injury-induced changes on the tendons microstructure. However, conventional spin-echo based DTI techniques often lead to poor tendon MR signal and difficulty on diffusion quantification, mainly due to the short tendon T2/T2* relaxation time constant. In this study, a novel method of combining stimulated-echo based DTI and readout-segmented multi-shot EPI (ste-RESOLVE) has been developed and evaluated. TE value can be as low as 20 ms for b value of 800 s/mm², enabling robust investigation of Achilles tendon microscopic tissue integrity on clinical MR scanners. 

Masami Yoneyama¹, Hajime Tanji², Tomoya Yamaki², Daisuke Takahashi², Makoto Obara¹, Tomoyuki Okuaki³, and Marc Van Cauteren^3
1Philips Electronics Japan, Tokyo, Japan, ²Kita-Fukushima Medical Center, Fukushima, Japan, ³Philips Healthcare Asia Pacific, Tokyo, Japan

Simultaneous acquisition of both MR angiography and MR neurography would be extremely helpful for diagnosing thoracic outlet syndrome. This study proposed a novel sequence, motion-sensitized driven-equilibrium (MSDE) prepared phase-cycling gradient echo (pcMSDE), for achieving simultaneous depiction of both MR angiography and MR neurography. By using this sequence, MR neurography images were obtained by MSDE (with motion sensitized gradient (MSG)) scan. MR angiography images were obtained by subtraction between “b0” scan (without MSG) and MSDE (with MPG) images. Additionally, this sequence could simultaneously offer the anatomical proton-density images and “self-fusion” images (MR NeuroAngiography) by using MR neurography and MR angiography. This sequence has great potential to help the diagnosis for any type of TOS. Further clinical investigation is needed.

Anna M. WANG^1,2 and Ed X. Wu^1,2
1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, China, People's Republic of, ²Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China, People's Republic of

We measured the apparent diffusion coefficients (ADCs), as well as the relative concentrations of both intramyocellular lipid (IMCL) and creatine in the rat muscle ischemia model. Comparing with the metabolite concentration changes, the IMCL and creatine ADCs had largely increased during muscle ischemia and the IMCL ADC increase was more drastic than creatine. The IMCL ADC, measured by diffusion weighted MRS, had shown the potential to probe the alterations in lipid droplet size and lipid metabolism in skeletal muscles.

Suryanarayanan Sivaram Kaushik¹, Ajeet Gaddipati², Brian Hargreaves³, Dawei Gui⁴, Robert Peters², Tugan Muftuler⁵, and Kevin Koch^1
1Radiology, Medical College of Wisconsin, Milwaukee, WI, United States, ²GE Healthcare, Waukesha, WI, United States, ³Radiology, Stanford University, Stanford, CA, United States, ⁴GE Healthcare, Waukesh, WI, United States, ⁵Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States

While FSE-based multi-spectral imaging (MSI) sequences help overcome the artifacts caused by metallic hardware, diffusion-weighted imaging remains a challenge. The non-CPMG artifacts caused by adding diffusion lobes to an FSE train can be mitigated by modulating the phase of the refocusing pulses. Another solution involves splitting the contribution made by the spin and stimulated echoes (DUO acquisition). Here, we combine a 2D version of MSI with a PROPELLER-DUO sequence to obtain clinically-feasible, artifact-minimized, diffusion-weighted images in subjects that have cancerous lesions in close proximity to metallic hardware.  

Michael Wyss¹, Andrei Manoliu², Georg Spinner¹, Magda Marcon², Roger Luechinger¹, Daniel Nanz², Klaas P. Pruessmann¹, and Gustav Andreisek^2
1Institute for Biomedical Engineering, University of Zurich and ETH Zurich, Zurich, Switzerland, ²Institute of Diagnostic and Interventional Radiology, University Hospital Zurich and University of Zurich, Zurich, Switzerland

Reliable fat suppression is challenging but mandatory for clinical 7.0T imaging. Purpose of this study was to evaluate different fat suppression techniques for clinical 7.0T knee MRI. Eight volunteers were imaged at 7.0T (Achieva, Philips) using a dedicated 28-channel TX-knee coil (QED) and axial PDw-TSE sequences without fat suppression, with SPIR, with SPAIR, with SSGR and with the combination of SSGR+SPIR. 

Ashley Anne Williams¹, Matthew R Titchenal¹, and Constance R Chu^1
1Orthopaedic Surgery, Stanford University, Stanford, CA, United States

3-D cones UTE-T2* maps were examined in 22 subjects with reconstructed anterior cruciate ligaments (ACLR) and 16 uninjured controls for evidence of alterations to the subsurface cartilage matrix suggestive of cartilage at risk for early OA 2 years after surgery. Elevated UTE-T2* values in regions of deep tibiofemoral cartilage and in side-to-side UTE-T2* differences were detected. UTE-T2* values correlated to standard T2 values in tibial and posterolateral femoral regions. Together, these findings suggest that UTE-T2* mapping detects “pre-osteoarthritic” subsurface cartilage matrix changes that may occur following ACLR and thus can help to identify subjects at risk of developing OA. 

Guillaume Madelin¹, Ding Xia¹, Gregory Chang¹, Svetlana Krasnokutsky², Steven B Abramson², and Ravinder R Regatte^1
1Department of Radiology, New York University Langone Medical Center, New York, NY, United States, ²Department of Rheumatology, New York University Langone Medical Center, New York, NY, United States

In this longitudinal study, we measured the sodium concentration in knee cartilage in 12 patients with osteoarthritis (OA) with quantitative ²³Na MRI at 7 T. Sodium measurements were performed at baseline and 16 months follow-up (on average), with and without fluid suppression by inversion recovery (IR). We show that only fluid-suppressed measurements show a significant decrease of mean [Na⁺] in different regions of cartilage over 16 months follow-up in OA patients. Quantitative ²³Na IR-MRI could therefore be a useful imaging biomarker to monitor cartilage degradation over time, and help assess the efficiency of potential disease modifying OA drugs.

Valentina Pedoia¹, Colin Russell¹, Allison Randolph V¹, Keiko Amano¹, Xiaojuan Li¹, and Sharmila Majumdar^1
1University of California, San Francisco, San Francisco, CA, United States

MR quantitative T1ρ mapping has been extensively used to probe articular biochemical changes. While several studies are still limited to analyzing average T1ρ values, there is growing interest in the analysis of local patterns of T1ρ maps. A novel algorithm for locally studying knee relaxation times using Voxel-Based Relaxometry (VBR) was recently proposed. In this study we propose to couple VBR and Principal Component Analysis in order to analyze local pattern changes in OA and ACL patients. Specific features, behind the expected average elevation of T1ρ  values, are observed able to distinguish between OA, ACL and Controls subjects. 

Feliks Kogan¹, Audrey Fan¹, Emily McWalter¹, Edwin Oei², Andrew Quon¹, and Garry Gold^1
1Radiology, Stanford University, Stanford, CA, United States, ²Radiology, Erasmus Medical Center, Rotterdam, Netherlands

Osteoarthritis (OA) is a debilitating disease that affects 27 million?Americans, causing pain, stiffness and loss of mobility. Simultaneous PET-MR imaging provides an opportunity to combine metabolic information regarding bone remodeling with high resolution images on MR. This work demonstrates that simultaneous 18F-fluoride PET/MR may provide additional metabolic information regarding bone pathology seen on conventional MR. This will allow for a better understanding of the role of bone degeneration in OA disease processes. Additionally, 18F-fluoride PET/MR may detect knee abnormalities unseen on MRI alone and is a promising tool for detection of early metabolic changes in OA. 

Erin Kristine Englund¹, Zachary Bart Rodgers¹, Michael C Langham², Emile R Mohler³, Thomas F Floyd⁴, and Felix W Wehrli^2
1Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States, ²Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States, ³Department of Medicine, University of Pennsylvania, Philadelphia, PA, United States, ⁴Department of Anesthesiology, Stony Brook University, Stony Brook, NY, United States

A method to simultaneously measure blood flow, perfusion, venous oxygen saturation, and muscle T₂* using a 3-slice interleaved PASL, multi-echo GRE sequence is presented. The method, termed Velocity and Perfusion, Intravascular Venous Oxygen saturation and T₂* (vPIVOT) was assessed in five subjects during a series of ischemia-reperfusion paradigms. Results indicate that vPIVOT faithfully measures all four parameters at 4-second temporal resolution. Dynamic measurement of these parameters was completed following a bout of dynamic plantar flexion contractions. vPIVOT allows for quantification of muscle oxygen consumption and evaluation of macro/microvascular flow dynamics, and may be useful for the development of biophysical models.

Xeni Deligianni^1,2, Michele Pansini³, Meritxell Garcia⁴, Anna Hirschmann⁴, Arno Schmidt-Trucksäss⁵, Oliver Bieri¹, and Francesco Santini^1,2
1Department of Radiology, Division of Radiological Physics, University of Basel Hospital, Basel, Switzerland, ²Department of Biomedical Engineering, University of Basel, Basel, Switzerland, ³Radiology, Kantonsspital Basel-Landschaft, Brudeholz, Switzerland, ⁴Department of Radiology, University of Basel Hospital, Basel, Switzerland, ⁵Department of Sports Medicine, University of Basel, Basel, Switzerland

Magnetic Resonance Imaging can be used to provide structural and functional muscle information either from oxygenation or contraction imaging. Contraction imaging can be based on real-time imaging or on voluntary movements. However, synchronization of the acquisition is challenging. Here, we present a new method for accurate, quantitative measurement of muscle contraction using a commercially available electrical muscle stimulator. This allows the direct assessment of the reaction time of muscle fibers, contraction speed, displacement, and strain providing complementary information to electromyography. MR images of the vastus lateralis muscle of five healthy volunteers were acquired at 3 Tesla field strength during electro-stimulation.