Tumor Tissue Detection using Blood-Oxygen-Level-Dependent Functional MRI based on Independent Component Analysis

Accurate delineation of gliomas from the surrounding normal brain areas helps maximize tumor resection and improves outcome. Blood-oxygen-level-dependent (BOLD) functional MRI (fMRI) has been routinely adopted for presurgical mapping of the surrounding functional areas. For completely utilizing such imaging data, here we show the feasibility of using presurgical fMRI for tumor delineation. In particular, we introduce a novel method dedicated to tumor detection based on independent component analysis (ICA) of resting-state fMRI (rs-fMRI) with automatic tumor component identification. Multi-center rs-fMRI data of 32 glioma patients from three centers, plus the additional proof-of-concept data of 28 patients from the fourth center with non-brain musculoskeletal tumors, are fed into individual ICA with different total number of components (TNCs). The best-fitted tumor-related components derived from the optimized TNCs setting are automatically determined based on a new template-matching algorithm. The success rates are 100%, 100% and 93.75% for glioma tissue detection for the three centers, respectively, and 85.19% for musculoskeletal tumor detection. We propose that the high success rate could come from the previously overlooked ability of BOLD rs-fMRI in characterizing the abnormal vascularization, vasomotion and perfusion caused by tumors. Our findings suggest an additional usage of the rs-fMRI for comprehensive presurgical assessment

Die vergessene Hemisphäre: rechtshemisphärische Beiträge zu modalitäts-unabhängigen phonologischen Aspekten der Sprachverarbeitung im gesunden menschlichen Gehirn

This thesis investigates the representation of phonological language aspects in the healthy human brain, especially the contribution of the right hemisphere. Using functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS), it is demonstrated that the left and right supramarginal gyri are essential for phonological processing. It is also shown that the left as well as the right posterior inferior frontal gyri contribute to efficient phonological decisions. Finally, an fMRI study reveals a frontal network for phonological aspects of language production. These results demonstrate a contribution of both hemispheres to efficient phonological aspects of language comprehension as well as production. Together, these results question the notion of a left-dominant network of brain regions for language processing.In dieser Arbeit wurde die Repräsentation phonologischer Sprachaspekte im gesunden Gehirn untersucht. Von besonderem Interesse war der Beitrag der rechten Hemisphäre. Dabei wurde mit funktioneller Magnetresonanztomographie (fMRT) und transkranieller Magnetstimulation die Relevanz des linken und rechten Gyrus supramarginalis für phonologische Sprachaspekte nachgewiesen. Weiterhin wurde gezeigt, dass der linke und rechte posteriore Gyrus frontalis inferior ebenfalls essentiell für die phonologische Verarbeitung sind. Abschließend wurde mittels fMRT ein frontales Netzwerk identifiziert, das an phonologischen Aspekten der Sprachproduktion beteiligt ist. Insgesamt zeigen die vorliegenden Ergebnisse, dass Areale beider Hemisphären gleichermaßen relevant für effiziente phonologische Entscheidungen im gesunden Gehirn sind. Dies stellt die bisher in der Literatur vorherrschende Dominanz der linken Hemisphäre für die Verarbeitung von Sprache in Frage