Dushyant Kumar¹, Ravi Prakash Reddy Nanga¹, Deepa Thakuri¹, Neil Wilson², Hari Hariharan¹, and Ravinder Reddy^1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, ²Siemens Medical Solutions USA Inc, Malvern, PA, United States

Synopsis: As a noninvasive imaging biomarker, phosphorous magnetic resonance spectroscopy (31PMRS) has traditionally been used to measure the metabolic response of exercised skeletal muscle in humans and has contributed immensely to the vital understanding of muscle energetics. However, due to lack of spatial resolution in 31PMRS, it is difficult to resolve the intermuscular variabilities of creatine kinase kinetics. In this study we demonstrate that with proper placement of surface coil in a mild exercise study, the recovery constant for PCr determined from 31PMRS matches well with recovery constant measured from CrCEST using a volume coil for the same muscle group.

Ek T Tan¹, Julia Sternberg¹, Bin Lin¹, Hollis G Potter¹, and Darryl B Sneag^1
1Radiology and Imaging, Hospital for Special Surgery, New York, NY, United States

High resolution, T2-weighted two-point Dixon is an effective technique for MR neurography (MRN) and can potentially also provide quantitative assessment of muscle ‘edema’ and fatty infiltration, which occur in acute and chronic muscle denervation, respectively. However, low SNR and residual off-resonance can introduce severe bias that impedes accurate interpretation. This study demonstrated that principal component analysis (PCA) denoising and off-resonance correction methods significantly improved proton density fat fraction (PDFF) measurements in 28 patient datasets and in signal simulations. Reduced bias allowed for further application of a proposed water-weighted processing enhances nerve conspicuity by suppressing perineural fat signal.

Rachelle Crescenzi¹, Paula M.C. Donahue^2,3, Kalen J Petersen¹, Maria Garza¹, Kelsey Guerreso¹, Yu Luo¹, Joshua A. Beckman⁴, and Manus J. Donahue^1,5,6
1Radiology, Vanderbilt University Medical Center, Nashville, TN, United States, ²Dayani Center for Health and Wellness, Vanderbilt University Medical Center, Nashville, TN, United States, ³Physical Medicine and Rehabilitation, Vanderbilt University Medical Center, Nashville, TN, United States, ⁴Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN, United States, ⁵Neurology, Vanderbilt University Medical Center, Nashville, TN, United States, ⁶Psychiatry, Vanderbilt University Medical Center, Nashville, TN, United States

The lymphatic system comprises a central component of the circulatory system, yet imaging approaches to visualize lymphatics remain underdeveloped. We utilized MR lymphangiography and sodium MRI to confirm lymphatic impairment in patients with lymphedema of known causes, and in patients with the adipose disorder lipedema of unknown etiology. We report distinct profiles on MR lymphangiography that correlate with tissue sodium and fat deposition. Results provide evidence of lymphatic involvement in lipedema that informs disease mechanisms related to swelling, and more broadly relates to lymphatic clearance dysfunction in a range of diseases where sodium and fat are implicated.

Mei Wu^1,2, Yanping Xue¹, Yajun Ma¹, Claire Tang¹, Meghan Shen¹, Saeed Jerban¹, Eric Y Chang^1,3, and Jiang Du^1
1Department of Radiology, University of California, San Diego, San Diego, CA, United States, ²Department of Radiology, Guangzhou First People’s Hospital, School of Medicine, South China University of Technology, Guangzhou, China, ³Radiology Service, VA San Diego Healthcare System, San Diego, CA, United States

The study protocol included three-dimensional Ultrashort Echo Time Cones actual flip angle imaging (3D UTE-Cones-AFI) for T1 measurement and UTE-Cones with adiabatic T1ρ (AdiabT1ρ) preparation for AdiabT1ρ measurement. We applied the 3D UTE-Cones AdiabT1ρ sequence to healthy volunteers and patients with different degrees of OA for a systematic evaluation of its clinical performance. Results showed that the 3D UTE-Cones AdiabT1ρ sequence could be used for high resolution imaging and quantitative assessment of the knee cartilage, and that the AdiabT1ρ biomarker showed a significant positive relationship with WORMS.

Radhika Tibrewala¹, Valentina Pedoia¹, Matthew Bucknor¹, and Sharmila Majumdar^1
1Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States

Osteoarthritis (OA) is a joint disorder, consisting of cartilage degeneration and metabolic bone changes, which have previously been correlated by using [¹⁸F]-NaF PET/MRI in the knee. However, these correlations were derived using averaging methods in areas of [¹⁸F] uptake in the bone and surrounding cartilage T_1ρ/T₂ mean values, which could miss potential multifaceted mechanisms that are not spatially correlated in the joint. The goal of this study is to find complex patterns in OA by building a cartilage-bone interface and using principal component analysis to find cartilage-bone interactions and find associations with known manifestations of OA.

Lauren Watkins¹, James MacKay^2,3, Bryan Haddock⁴, Valentina Mazzoli⁵, Scott Uhlrich⁶, Garry Gold⁵, and Feliks Kogan^5
1Bioengineering, Stanford University, Stanford, CA, United States, ²Radiology, University of East Anglia, Norwich, United Kingdom, ³Radiology, University of Cambridge, Cambridge, United Kingdom, ⁴Department of Clinical Physiology, Nuclear Medicine and PET, Copenhagen University Hospital, København, Denmark, ⁵Radiology, Stanford University, Stanford, CA, United States, ⁶Mechanical Engineering, Stanford University, Stanford, CA, United States

Abnormal bone physiology is a potential mechanism for the progression of knee osteoarthritis. Molecular information derived from PET imaging has shown promise in early detection of bone metabolic abnormalities. Here we investigated kinetic parameters of PET tracer ([¹⁸F]-NaF) uptake in subjects with knee osteoarthritis and evaluated the relationship between kinetic tracer uptake parameters and structural MRI findings. The kinetic parameters for [¹⁸F]-NaF delivery and uptake to regions of bone containing osteophytes, bone marrow lesions, and adjacent to cartilage lesions identified on MRI were significantly different compared to normal-appearing bone, suggesting strong spatial relationships between structural damage and bone metabolic abnormalities.

Brandon Clinton Jones¹, Cheng-Chieh Cheng¹, Xia Zhao¹, Mona Al Mukaddam², Peter J Snyder², Chamith S Rajapakse¹, Hee Kwon Song¹, and Felix W Wehrli^1
1Radiology, University of Pennsylvania, Philadelphia, PA, United States, ²Medicine, University of Pennsylvania, Philadelphia, PA, United States

Seven osteoporotic treatment-naïve and 13 non-osteoporotic postmenopausal women have been examined in an ongoing MRI study to evaluate cortical bone properties. ¹H dual-echo UTE and ¹H IR-prepared rapid-UTE sequences were used for evaluation of pore and bound water concentrations in the tibial cortex, and a ³¹P PETRA-ZTE sequence for quantification of cortical bone mineralization. Elevated total water and pore water were found in the osteoporotic group (p=0.036, p=0.032), whereas ³¹P and bound water concentrations were not significantly different. Since pore water is a known surrogate of bone porosity, our preliminary results suggest it may be useful in evaluating bone health.

Esha Baidya Kayal¹, Nikhil Sharma¹, Sameer Bakhshi², Raju Sharma³, Devasenathipathy Kandasamy³, and Amit Mehndiratta^1,4
1Centre for Biomedical Engineering, Indian Institute of Technology, Delhi, New Delhi, India, ²Department of Medical Oncology, Dr. B.R. Ambedkar Institute-Rotary Cancer Hospital (IRCH), All India Institute of Medical Sciences, New Delhi, New Delhi, India, ³Radio Diagnosis, All India Institute of Medical Sciences, New Delhi, New Delhi, India, ⁴Department of Biomedical engineering, All India Institute of Medical Sciences, New Delhi, New Delhi, India

Histopathological examination is the current gold standard for evaluating tumor response to anti-cancer therapy; though it is possible only after surgery. Non-invasive imaging biomarkers of tumor response to therapy may be useful in optimizing existing treatments improving overall outcome. The spin-lattice relaxation time of water protons (T1) reflects therapeutic changes in tumor and is thus a generic marker of tumor response to therapy. Experimental results showed T1 relaxation time reduces upon successful chemotherapy and thus, a change in tumor T1 may be a non-invasive imaging marker of chemo-sensitivity and chemotherapy response.

Marcus Raudner¹, Markus Schreiner^1,2, Tom Hilbert^3,4,5, Tobias Kober^3,5,6, Anna Szelenyi⁷, Vladimir Juras¹, and Siegfried Trattnig^1
1High Field MR Centre, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria, ²Department of Orthopedics and Trauma Srugery, Medical University of Vienna, Vienna, Austria, ³Advanced Clinical Imaging Technology, Siemens Healthcare, Lausanne, Switzerland, ⁴Department of Radiology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland, ⁵LTS5, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland, ⁶Department of Radiology, University Hospital and University of Lausanne, Lausanne, Switzerland, ⁷Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria

The physiological biochemical state of the intervertebral disc (IVD) allows for passive water-storing capabilities because of a high concentration of glycosaminoglycans (GAG) and an inherent structural integrity. T₂ mapping can quantitatively assess the IVD’s water content and GAG concentration, but a typical 2D multi echo spin echo (MESE) sequence suffers from clinically prohibitive scan times. To resolve this, we compared the MESE sequence against GRAPPATINI, an accelerated sequence combining parallel imaging and a model-based reconstruction for T₂ quantification which uses undersampling to shorten the scan time from 13:18 to 2:27 minutes.