Browsing by Subject "magnetic resonance imaging (MRI)"

Now showing 1 - 4 of 4
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    Anatomic, functional and molecular imaging in lung cancer precision radiation therapy: treatment response assessment and radiation therapy personalization
    (2017-12) MacManus, Michael; Everitt, Sarah; Schimek-Jasch, Tanja; Li, X. Allen; Nestle, Ursula; Kong, Feng-Ming (Spring); Medicine, School of Medicine
    This article reviews key imaging modalities for lung cancer patients treated with radiation therapy (RT) and considers their actual or potential contributions to critical decision-making. An international group of researchers with expertise in imaging in lung cancer patients treated with RT considered the relevant literature on modalities, including computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). These perspectives were coordinated to summarize the current status of imaging in lung cancer and flag developments with future implications. Although there are no useful randomized trials of different imaging modalities in lung cancer, multiple prospective studies indicate that management decisions are frequently impacted by the use of complementary imaging modalities, leading both to more appropriate treatments and better outcomes. This is especially true of 18F-fluoro-deoxyglucose (FDG)-PET/CT which is widely accepted to be the standard imaging modality for staging of lung cancer patients, for selection for potentially curative RT and for treatment planning. PET is also more accurate than CT for predicting survival after RT. PET imaging during RT is also correlated with survival and makes response-adapted therapies possible. PET tracers other than FDG have potential for imaging important biological process in tumors, including hypoxia and proliferation. MRI has superior accuracy in soft tissue imaging and the MRI Linac is a rapidly developing technology with great potential for online monitoring and modification of treatment. The role of imaging in RT-treated lung cancer patients is evolving rapidly and will allow increasing personalization of therapy according to the biology of both the tumor and dose limiting normal tissues.
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    MRI Measures of Neurodegeneration as Biomarkers of Alzheimer's Disease
    (2012-03-19) Risacher, Shannon Leigh; Shen, Li; Farlow, Martin R.; Gao, Sujuan; McDonald, Brenna C.; Saykin, Andrew J.; Yoder, Karmen K.
    Alzheimer’s disease (AD) is the most common age-related neurodegenerative disease. Many researchers believe that an effective AD treatment will prevent the development of disease rather than treat the disease after a diagnosis. Therefore, the development of tools to detect AD-related pathology in early stages is an important goal. In this report, MRI-based markers of neurodegeneration are explored as biomarkers of AD. In the first chapter, the sensitivity of cross-sectional MRI biomarkers to neurodegenerative changes is evaluated in AD patients and in patients with a diagnosis of mild cognitive impairment (MCI), a prodromal stage of AD. The results in Chapter 1 suggest that cross-sectional MRI biomarkers effectively measure neurodegeneration in AD and MCI patients and are sensitive to atrophic changes in patients who convert from MCI to AD up to 1 year before clinical conversion. Chapter 2 investigates longitudinal MRI-based measures of neurodegeneration as biomarkers of AD. In Chapter 2a, measures of brain atrophy rate in a cohort of AD and MCI patients are evaluated; whereas in Chapter 2b, these measures are assessed in a pre-MCI stage, namely older adults with cognitive complaints (CC) but no significant deficits. The results from Chapter 2 suggest that dynamic MRI-based measures of neurodegeneration are sensitive biomarkers for measuring progressive atrophy associated with the development of AD. In the final chapter, a novel biomarker for AD, visual contrast sensitivity, was evaluated. The results demonstrated contrast sensitivity impairments in AD and MCI patients, as well as slightly in CC participants. Impaired contrast sensitivity was also shown to be significantly associated with known markers of AD, including cognitive impairments and temporal lobe atrophy on MRI-based measures. The results of Chapter 3 support contrast sensitivity as a potential novel biomarker for AD and suggest that future studies are warranted. Overall, the results of this report support MRI-based measures of neurodegeneration as effective biomarkers for AD, even in early clinical and preclinical disease stages. Future therapeutic trials may consider utilizing these measures to evaluate potential treatment efficacy and mechanism of action, as well as for sample enrichment with patients most likely to rapidly progress towards AD.
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    Posterior Reversible Encephalopathy Syndrome: The Riley Experience
    (Office of the Vice Chancellor for Research, 2016-04-08) Meyer, Ashley
    Abstract: Background: Posterior reversible encephalopathy syndrome (PRES) is a severe neurologic complication associated with many disease processes that can be difficult to diagnose. PRES is a clinicoradiological disease entity represented by characteristic magnetic resonance imaging (MRI) findings, and one of the following clinical features: seizures, headaches, altered levels of mental status, and cortical blindness. Despite growing recognition, debate about the true cause and risk factors remain. To date, this is the largest retrospective chart review of pediatric patients with PRES and evaluates patients across a wide variety of diagnoses. Methods: Pediatric patients presenting to Riley Hospital for Children between January 1, 2003 and December 31, 2014 for PRES were identified retrospectively. Chart review identified true cases of PRES, and underlying diagnosis and risk factors. Of the 129 patients identified, 86 were confirmed cases of PRES. Results: The underlying diagnosis in patients presenting with PRES mainly included nephrogenic diseases, oncologic disease, and pregnancy. Due to the broad range of underlying etiologies, no class of medications was identified as a cause. However, hypertension was strongly associated with development of PRES. Of the 86 confirmed cases, 82 had complete data for analysis revealing 80 patients with hypertension at the onset of symptoms (97.6%). Underscoring the severity of the disease, 63 of the 86 confirmed cases of PRES required pediatric intensive care (73%). Despite the severity of the syndrome, recognition and appropriate therapy allowed for improvement in the majority of patients. Four patients died from their underlying disease process and one patient developed a seizure disorder. Conclusion: PRES is severe complication that can impact patients across a variety of diseases. Close attention must be paid to diseases associated with hypertension. Although previously thought to be a result of direct cytotoxic effects of medication, this study shows hypertension is more strongly associated with development of PRES than medications. While generally reversible, symptoms are often severe enough to require treatment in an intensive care unit. Early diagnosis and correction of blood pressure is important for optimum patient care.
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    Use of multimodality imaging, histology, and treatment feasibility to characterize a transgenic Rag2-null rat model of glioblastoma
    (Frontiers, 2022-11-22) Jackson, Luke R.; Masi, Megan R.; Selman, Bryce M.; Sandusky, George E.; Zarrinmayeh, Hamideh; Das, Sudip K.; Maharjan, Surendra; Wang, Nian; Zheng, Qi-Huang; Pollok, Karen E.; Snyder, Scott E.; Sun, Phillip Zhe; Hutchins, Gary D.; Butch, Elizabeth R.; Veronesi, Michael C.; Pediatrics, School of Medicine
    Many drugs that show potential in animal models of glioblastoma (GBM) fail to translate to the clinic, contributing to a paucity of new therapeutic options. In addition, animal model development often includes histologic assessment, but multiparametric/multimodality imaging is rarely included despite increasing utilization in patient cancer management. This study developed an intracranial recurrent, drug-resistant, human-derived glioblastoma tumor in Sprague–Dawley Rag2-Rag2 tm1Hera knockout rat and was characterized both histologically and using multiparametric/multimodality neuroimaging. Hybrid 18F-fluoroethyltyrosine positron emission tomography and magnetic resonance imaging, including chemical exchange saturation transfer (18F-FET PET/CEST MRI), was performed for full tumor viability determination and characterization. Histological analysis demonstrated human-like GBM features of the intracranially implanted tumor, with rapid tumor cell proliferation (Ki67 positivity: 30.5 ± 7.8%) and neovascular heterogeneity (von Willebrand factor VIII:1.8 to 5.0% positivity). Early serial MRI followed by simultaneous 18F-FET PET/CEST MRI demonstrated consistent, predictable tumor growth, with exponential tumor growth most evident between days 35 and 49 post-implantation. In a second, larger cohort of rats, 18F-FET PET/CEST MRI was performed in mature tumors (day 49 post-implantation) for biomarker determination, followed by evaluation of single and combination therapy as part of the model development and validation. The mean percentage of the injected dose per mL of 18F-FET PET correlated with the mean %CEST (r = 0.67, P < 0.05), but there was also a qualitative difference in hot spot location within the tumor, indicating complementary information regarding the tumor cell demand for amino acids and tumor intracellular mobile phase protein levels. Finally, the use of this glioblastoma animal model for therapy assessment was validated by its increased overall survival after treatment with combination therapy (temozolomide and idasanutlin) (P < 0.001). Our findings hold promise for a more accurate tumor viability determination and novel therapy assessment in vivo in a recently developed, reproducible, intracranial, PDX GBM.