Liam S. P. Lawrence^1,2, Rachel W. Chan¹, James Stewart³, Mark Ruschin³, Aimee Theriault³, Sten Myrehaug³, Jay Detsky³, Pejman J. Maralani⁴, Chia-Lin Tseng³, Greg J. Stanisz^1,2,5, Arjun Sahgal³, and Angus Z. Lau^1,2
1Physical Sciences Platform, Sunnybrook Research Institute, Toronto, ON, Canada, ²Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada, ³Department of Radiation Oncology, Sunnybrook Health Sciences Centre, Toronto, ON, Canada, ⁴Department of Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, ON, Canada, ⁵Department of Neurosurgery and Paediatric Neurosurgery, Medical University, Lublin, Poland

For radiotherapy of high-grade glioma, dose escalation to hypercellular tumour could improve local control, but changes during treatment might necessitate target volume adaptation. Since hypercellular tumour causes low apparent diffusion coefficient (ADC) values, volumetric changes in low-ADC regions were quantified using near-daily MR-Linac imaging to evaluate adaptation necessity. Low-ADC regions increased in volume (median extremal change: 12.2%) and changed rapidly for certain patients (maximum growth/shrinkage rate: 7.1/9.1% per day). Low-ADC regions changed more in magnitude and grew more rapidly for resected tumours than intact ones. These findings imply that adaptation may be required for dose escalation to hypercellular glioma regions.

Lok Hin LAW¹, Jianpan Huang¹, Yang Liu¹, Peng Xiao¹, Ho Chi Joseph Lai¹, Zilin Chen¹, and Kannie W.Y. CHAN^1,2,3,4
1Department of Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong, ²Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, United States, ³City University of Hong Kong Shenzhen Research Institute, Shenzhen, China, ⁴Hong Kong Centre for Cerebro-Cardiovascular Health Engineering (COCHE), Hong Kong, Hong Kong

Nose-to-brain-drug-delivery is an effective route to administer drug to the brain bypassing the blood-brain-barrier(BBB). No non-invasive way to assess the delivery-efficiency available yet, especially with brain distribution. Here we investigated the imaging of nanomedicine-delivery via intranasal-administration using CEST-detectable(Iohexol loaded)mucus-penetrating-liposome(with10%PEG). The mucus-retention and penetration-efficiency was examined by in-vitro cell study and in-vivo CEST MRI after injecting the Iohexol-loaded-mucus-penetrating-liposome(Ioh-Lipo). 10%PEG-Ioh-Lipo showed a 20%higher mucus-retention than 1%PEG-Ioh-Lipo. This was also observed in-vivo with significant CEST-contrast difference in the OB between 3groups of mice at 4.3 and 3.5ppm. Moreover, liposomes were mainly found in the ONL, EPL, and MCL of the OB in histology. 

Xiang Shan¹, Matthew C Murphy¹, Yi Sui¹, Keni Zheng¹, Armando Manduca², Richard L Ehman¹, John Huston III¹, and Ziying Yin^1
1Radiology, Mayo Clinic, Rochester, MN, United States, ²Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States

Repetitive head impact (RHI) increases the risk of concussion, probably due to alterations of the brain-skull mechanical coupling. It would be of clinical value to have a reliable biomarker capable of assessing the status of the brain-skull coupling condition. MRE-based normalized octahedral shear strain (NOSS) has been proposed as a method for such brain membrane system evaluation. To verify the test-retest reliability of NOSS, datasets from 14 healthy volunteers were acquired with different vibration directions and within- and between-day scanning. This study demonstrated the excellent repeatability of the proposed method, showing the NOSS distributions were robust to loading variations.

Teddy Salan¹, Sameer Vyas², Deepika Aggarwal², Paramjeet Singh², and Varan Govind^1
1Radiology, University of Miami, Miami, FL, United States, ²Post Graduate Institute of Medical Education & Research, Chandigarh, India

HIV clade-C, found in 50% of HIV cases worldwide, has been reported to have lower neurovirulence than clade-B, more common in the global north. Numerous DTI-based studies have investigated HIV-associated microstructural damage in the brain, yet few looked at clade-C in particular. Moreover, some have reported inconsistent DTI results with respect to HIV. In this study, we use DTI and DKI to determine the extent of microstructural brain damage due to HIV clade-C infection. Our results show that a combined use of DTI and DKI can provide a better description of brain tissue damage among HIV clade-C infected individuals.
 

Jake Valsamis¹, Nicholas Luciw¹, Walter Swardfager^2,3, Andrew Lim^2,4, Joel Ramirez², Sandra Black^2,4, and Bradley J MacIntosh^1,5
1Physical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada, ²Evaluative Clinical Sciences, Sunnybrook Research Institute, Toronto, ON, Canada, ³Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada, ⁴Department of Medicine, University of Toronto, Toronto, ON, Canada, ⁵Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada

Measuring intracranial vascular compliance (VC) may help characterize a patient’s resilience to Alzheimer’s disease and dementia. In this study, we estimate VC from a BOLD MRI cerebrovascular reactivity (CVR) protocol by measuring cardiac-related BOLD pulsatility and end-tidal CO₂ during periods of hypercapnia and normocapnia. We measured high VC in regions proximal to major cerebral arteries like the thalamus and insula, and low VC in the parietal lobe. This study demonstrates the feasibility of extracting additional information from BOLD-CVR experiments and suggests regional differences in VC. Future work will include a second cohort to estimate VC in different patient populations.

Dinesh K Deelchand¹, Pierre-Gilles Henry¹, James M Joers¹, Edward Auerbach ¹, Young Woo Park¹, Firat Kara², Eva Ratai³, Kejal Kantarci², and Gülin Öz^1
1University of Minnesota, Minneapolis, MN, United States, ²Mayo Clinic, Rochester, MN, United States, ³Massachusetts General Hospital, Charlestown, MA, United States

We developed an automated advanced-single-voxel MRS acquisition protocol at 3T to facilitate acquisition of high-quality spectroscopic data without local MRS expertise. Voxel-based B0 and B1 calibrations were incorporated into the consensus-recommended semi-LASER sequence and combined with automated voxel prescription. Automated B0 and B1 calibrations saved ~4.5min per voxel vs. manual calibrations. All spectra acquired with the automated protocol by rotating MR technologists were usable, while only 83% of those collected with the manual protocol were usable and spectral quality was more variable. The protocol allows automated acquisition of high-quality MRS data with high success rate on a clinical 3T platform.

Yosef Chodakiewitz¹, David Arnold Purger¹, Alan Rehn Wang¹, Daniel Barbosa¹, Lior Lev Tov¹, Anjali Datta¹, Rachelle Bitton¹, Jennifer McNab¹, Vivek Buch¹, and Pejman Ghanouni^1
1Stanford University, Stanford, CA, United States

While Focused-Ultrasound thalamotomy has proven effective at reducing tremor, traditional targeting methods can be suboptimal at balancing primary tremor-reduction outcomes against undesired side-effects. The traditional “canonical” technique involves an indirect method which applies a non-individualized stereotactic coordinate atlas towards identifying the presumed approximate location of VIM thalamus, the ablation target; the canonical lesion is empirically grown in size based-on dynamic intraoperative feedback from an awake patient, until the surgeon judges that an appropriate balance of tremor-reduction and side-effect risk has been achieved. We propose optimized methods to define and monitor the ideal anatomical ablation for optimized tremor-reduction/Quality-of-Life balancing.