Jenny Chen¹, Benjamin Ades-aron¹, Hong-Hsi Lee², Durga Kullakanda¹, Saurabh Maithani¹, Dmitry S. Novikov¹, Jelle Veraart¹, and Els Fieremans^1
1Department of Radiology, NYU School of Medicine, New York, NY, United States, ²Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States

Diffusion MRI (dMRI) is affected by noise and by artifacts such as Gibbs ringing and distortions. Using software phantoms as ground-truth, this study compares diffusion tensor imaging (DTI) and diffusional kurtosis imaging (DKI) parameter estimates to assess accuracy of various denoising and Gibbs removal methods, two key components of dMRI pipelines. An optimized Diffusion parameter EStImation with Gibbs and NoisE Removal (DESIGNER) pipeline is proposed, with non-local patch MP-PCA denoising and Removal of Partial-fourier induced Gibbs Ringing (RPG), that yields more accurate metrics, fewer outlier voxels in phantoms and more robust DTI/DKI maps in patient data.

Florian Gierse¹, Juela Cufe¹, Bastian Maus², Katharina Kronenberg³, Michael Claesener⁴, Paulina Dorten¹, Klaus Schäfers¹, Sven Hermann¹, Uwe Karst³, Cornelius Faber², Michael Schäfers⁴, Florian Büther⁴, and Philipp Backhaus^4
1European Institute for Molecular Imaging, University of Münster, Münster, Germany, ²Translational Research Imaging Center, University of Münster, Münster, Germany, ³Institute of Inorganic and Analytical Chemistry, University of Münster, Münster, Germany, ⁴Department of Nuclear Medicine, University Hospital Münster, Münster, Germany

Quantitative precise measurements of the dynamic arterial blood concentration (AIF) are challenging in perfusion MRI. As solution an extracorporeal circulation approach for the AIF determination with two different vascular access ways is presented and cross validated with injection of radioactive contrast agent derivatives. Independent of the vascular access way, extracorporeal derived AIFs point towards a high quantitative precision, although dispersion must be considered. However, deconvolution methods based on single gamma variate functions end up in plausible AIFs. The use of novel rapid imaging techniques in connection with extracorporeal AIFs indicates high potential for precise quantitative dual PET/MRI Pharmacokinetic-Modeling in mice.

L. Tyler Williams¹, Katrina A. Milbocker², Seth R. Sullivan¹, Ian F. Smith², Eric Brengel², Gillian LeBlanc², Anna Y. Klintsova², Matthew D. J. McGarry³, and Curtis L. Johnson^1
1Biomedical Engineering, University of Delaware, Newark, DE, United States, ²Psychological & Brain Sciences, University of Delaware, Newark, DE, United States, ³Thayer School of Engineering, Dartmouth College, Hanover, NH, United States

Developing preclinical MRE techniques that are comparable to human MRE is important for translational studies. This pilot study investigates the efficacy of the nonlinear inversion algorithm on rat brain MRE data. Whole-brain MRE scans were performed on female, Long-Evans rats using a custom MRE-EPI sequence and piezoelectric actuator with a resolution of 0.25 mm isotropic and with 600 Hz vibration. NLI parameters were adjusted for brain size and frequency. The resulting shear stiffness and damping ratio maps exhibited strong contrast between different anatomical regions. These results validate the use of NLI in preclinical MRE settings.       

Mikael Montelius¹, Lukas Lundholm¹, Oscar Jalnefjord^1,2, Eva Forssell-Aronsson^1,2, and Maria Ljungberg^1,2
1Medical radiation sciences, Institute of Clinical Sciences, University of Gothenburg, Gothenburg, Sweden, ²Medical Physics and biomedical engineering, Sahlgrenska University Hospital, Gothenburg, Sweden

The biological meaning of MRI-based biomarkers of cancer can be studied using spatially matched histologically stained tumor sections. However, correlations are often weak or contradictory, possibly due to confounding necrosis that models fail to describe. In this work, we demonstrate the potential of using VERDICT MRI model parameters to separate necrosis from viable tumor tissue non-invasively. Radiation treated tumors demonstrating large necrotic and viable regions are imaged, excised and stained using immunohistochemical methods. Correlations between spatially matched VERDICT and immunohistochemical maps reveal that VERDICT clearly separates necrosis from viable tumor.