Rasha M. Elmghirbi^1,2, Stephen L. Brown³, Tavarekere N. Nagaraja⁴, Madhava P. Aryal^2,5, Kelly Ann Keenan⁴, Swayamprav Panda², Hassan Bagher-Ebadian², and James R. Ewing^1,2
1Physics, Oakland University, Rochester, MI, United States, ²Neurology, Henry Ford Health System, Detroit, MI, United States, ³Radiation Oncology, Henry Ford Health System, Detroit, MI, United States, ⁴Anesthesiology, Henry Ford Health System, Detroit, MI, United States, ⁵Radiation Oncology, University of Michigan, Ann Arbor, MI, United States

The acute response in a U251 rat model of embedded cerebral tumor high-dose radiotherapy (HD-RT) is studied by measuring blood flow and vascular parameters in the tumor, and tissue compression in the periphery of the tumor. At 2 and 4 hours post HD-RT a profound decrease in tumor blood flow accompanies a significant decrease in extracellular space in both the tumor and its periphery. Decoupling of tissue compression and blood flow occurs about 8 hours after HD-RT.

Xiaowei Zou¹, Wei Bian², Jonathan I. Tamir³, Suchandrima Banerjee⁴, Susan M. Chang⁵, Michael Lustig³, Sarah J. Nelson¹, and Janine M. Lupo^1
1University of California San Francisco, San Francisco, California, United States, ²Radiology, Stanford University, Stanford, California, United States,³Electrical Engineering and Computer Science, University of California Berkeley, Berkeley, CA, United States, ⁴Global Applied Science Laboratory, GE Healthcare, Menlo Park, CA, United States, ⁵Neurological Surgery, University of California San Francisco, San Francisco, CA, United States

Radiation therapy is a widely utilized treatment for gliomas. However, it can result in collateral injury to normal-appearing brain tissue, such as the formation of cerebral microbleeds (CMBs). The ability to assess characteristics of CMBs in conjunction with the surrounding arterioles and venules would help to identify underlying vascular injury. In this study, a seven-echo sequence was implemented and optimized for multi-echo multi-contrast high-resolution vascular imaging at 3T within a clinically feasible scan time. The fitted R2* maps can differentiate small-size CMBs and cystic changes, demonstrating the potential benefit of this sequence in routine clinical evaluation of CMBs.

Moran Artzi^1,2, Gilad Liberman^1,3, Guy Nadav^1,4, Deborah T Blumenthal⁵, Felix Bokstein⁵, Orna Aizenstein¹, and Dafna Ben Bashat^1,6
1Functional Brain Center, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel, ²Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel,³Department of Chemical Physics, Weizmann Institute, Rehovot, Israel, ⁴Faculty of Engineering, Tel Aviv University, Tel Aviv, Israel, ⁵Neuro-Oncology Service, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel, ⁶Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel

Differentiation between progressive-disease (PD) and treatment-necrosis (TN) in patients with Glioblastoma remains a major clinical challenge. In this study the enhanced tumor area was automatically identified from the raw DCE data using ICA. Voxel-based classification was performed using SVM based on the DCE pharmacokinetic parameters in eighteen patients scanned longitudinally (total of 60 MRI scans). Significant differences were obtained between transfer-constants, plasma-volume and bolus-arrival-time in the different tissue classes (PD and TN), and compared to NAWM. High sensitivity (89.3%) and specificity (89.4%) were obtained using two-fold cross-validation design. Classification results were validated by a senior neuro-radiologist and supported by MRS.

Iska Moxon-Emre^1,2, Eric Bouffet¹, Michael D Taylor^1,2, Normand Laperriere^2,3, Michael Sharpe^2,3, Suzanne Laughlin¹, Nadia Scantlebury¹, Nicole Law^1,2, David Malkin^1,2, Jovanka Skocic¹, Logan Richard^1,2, and Donald Mabbott^1,2
1Hospital for Sick Children, Toronto, Ontario, Canada, ²University of Toronto, Toronto, Ontario, Canada, ³University Health Network, Toronto, Ontario, Canada

This study examined white matter (WM) in children treated for medulloblastoma with different clinically relevant radiation dose and boost volumes, using diffusion tensor imaging (DTI). We found that relative to controls, patients treated with higher doses and/or larger boost volumes show more compromised WM than patients treated with the least intensive therapy (i.e. reduced dose CSR and a boost limited to the tumor bed). This was particularly evident in the temporal lobes, a brain region encompassed by a lateral beam boost to the posterior fossa (PF). Our findings suggest the PF boost should be avoided whenever possible.

Peter MK de Blank¹, Michael J Fisher², Timothy PL Roberts², and Jeffrey I Berman^2
1UH Case Medical Center, Cleveland, OH, United States, ²The Children's Hospital of Philadelphia, PA, United States

Although chemotherapy has been associated with cognitive deficits and changes in white matter integrity, the effect of low-intensity chemotherapy (separate from surgery and radiation) has not been examined. We examined diffusion tensor imaging (DTI) in 12 age-matched pairs of children with neurofibromatosis type 1 and optic pathway glioma with or without exposure to low-intensity chemotherapy, and without exposure to surgery or radiation. Subjects exposed to low-intensity chemotherapy had decreased FA in tracts previously associated with cognitive deficits. Two subjects with DTI scans before and after exposure to chemotherapy showed decrease in FA over 1 year.

Melissa A Prah¹, Mona M Al-Gizawiy¹, Wade M Mueller², Raymond G Hoffmann³, Mahua Dasgupta³, and Kathleen M Schmainda^1,4
1Radiology, Medical College of Wisconsin, Milwaukee, WI, United States, ²Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, United States,³Pediatrics, Medical College of Wisconsin, Milwaukee, WI, United States, ⁴Biophysics, Medical College of Wisconsin, Milwaukee, WI, United States

In brain tumor patients, pseudoprogression, which results from an inflammatory response associated with necrotic and radiation induced changes, has been shown to mimic early tumor progression on standard imaging. The goal of this study was to compare the ability of diffusion and perfusion parameters in differentiating radiation effect/necrosis (RE/Necrosis) from glioblastoma (GBM). Using tissue samples spatially-correlated to pre-surgical imaging, this work demonstrates that relative cerebral blood volume (rCBV) better distinguishes RE/Necrosis from GBM than relative cerebral blood flow or the apparent diffusion coefficient. Spatially visualizing differentiated regions of RE/Necrosis and GBM with rCBV may ultimately impact treatment management decisions.

Anagha Deshmane¹, Chaitra Badve², Matthew Rogers³, Alice Yu³, Dan Ma¹, Jeffrey Sunshine², Vikas Gulani², and Mark Griswold^2
1Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States, ²Radiology, University Hospitals, Cleveland, OH, United States, ³School of Medicine, Case Western Reserve University, Cleveland, OH, United States

Magnetic resonance fingerprinting (MRF) can be used to simultaneously map T1, T2 and off-resonance. It was previously demonstrated that modeling single voxel MRF signals as a weighted sum of evolutions from known tissue types can be used to quantify subvoxel tissue fractions in the brain and perform tissue segmentation. Here MRF is used to estimate fractions of free fluid, intra/extracellular water, and myelin water in brain tumor patients with glioblastoma multiforme and metastases. A significant difference in free fluid and intra/extracellular water fraction was found in perilesional white matter between the two patient groups.

Mary A McLean¹, Stephen J Price², Ferdia A Gallagher³, and John R Griffiths^1
1Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom, ²Dept of Neurosurgery, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom, ³Dept of Radiology, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom

We investigated relationships between MR measures of perfusion, diffusion, T2-hyperintensity, and metabolite content in 7 newly-diagnosed gliomas at 3T. Parameterized subtraction maps of high-resolution T1-weighted images obtained ~5 and ~50 min after gadolinium injection showed a non-enhanced tumour core, correlating positively with lactate and negatively with creatine and choline, as distinct from a late-enhancing area which had a metabolic profile more similar to active tumour. ADC and T2-hyperintensity correlated with each other but not with either MRS or perfusion. Maps of delayed enhancement may provide a useful high-resolution surrogate for metabolic information, but further validation is needed.

Ingrid Digernes¹, Frédéric Courivaud¹, Cathrine Saxhaug², Marco C. Pinho³, Oliver M. Geier¹, Einar Vik-Mo⁴, Knut Haakon Hole⁵, Grete Lovland¹, Svein Are Vatnehol¹, Torstein R. Meling⁴, Otto Rapalino⁶, Atle Bjornerud^1,7, and Kyrre E. Emblem^1
1The Intervention Centre, Oslo University Hospital, Oslo, Oslo, Norway, ²Department of Radiology, Oslo University Hospital, Oslo, Norway, ³Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX 75235, United States, ⁴Department of Neurosurgery, Oslo University Hospital, Oslo, Norway, ⁵Departement of Radiology, Oslo University Hospital, Oslo, Norway, ⁶Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, United States, ⁷Department of Physics, University of Oslo, Oslo, Norway

We have used Vessel Architectural Imaging to reveal mechanisms of vascular remodelling in tumor and regions of peritumoral edema by comparing results from gliobastomas(GBMs) and metastatic brain tumors(METs). We found that the relative oxygen saturation level in tumor and edema regions were significantly higher in GBMs compared to METs and that vessel calibres of GBMs were larger than those of METs in tumor. This suggests that there are marked differences in tumoral and peritumoral vascular microenvironments in primary and metastatic brain tumors and that advanced MRI techniques may give valuable insights into the mechanisms of angiogenesis and growth in brain tumor patients.

Pia Eriksson¹, Myriam M Chaumeil¹, Joydeep Mukherjee^2,3, Russell O Pieper^2,3, and Sabrina M Ronen^1,3
1Radiology & Biomedical Imaging, University of California San Francisco, San Francisco, CA, United States, ²Neurological Surgery, University of California San Francisco, San Francisco, CA, United States, ³Brain Tumor Research Center, University of California San Francisco, CA, United States