Date of Award

2010

Degree Type

Dissertation

Department

Chemical and Biomedical Engineering

First Advisor

Yue, Guang H.

Subject Headings

Magnetic resonance imaging, Brain -- Magnetic resonance imaging, Amyotrophic lateral sclerosis, Motor neurons, Pyramidal tract, MRI, UMN, LMN, DTI, CST

Abstract

Amyotrophic lateral sclerosis (ALS) is the commonest adult motor neuron disease (MND) which causes progressive muscle paralysis and death usually within 5 years of symptom onset. As a result, only ̃30,000 individuals in the United States are afflicted at any one time even though 5,000 or more individuals are diagnosed yearly. The diagnosis of ALS requires evidence of degeneration in upper motor neurons (UMNs) in the brain and in lower motor neurons (LMNs) that exit the brainstem and spinal cord to innervate skeletal muscles. Diagnosis can be incorrect or delayed when disease is early or atypical because non-invasive objective tests of UMN involvement do not exist, unlike electromyography to assess the LMN. Although magnetic resonance imaging (MRI) of brain and spinal cord is used primarily to identify conditions which mimic ALS, novel MRI sequences and post-processing techniques can identify macroscopic and even sub-macroscopic changes in ALS brain related to neuronoaxonal degeneration (e.g., in corticospinal motor tracts). MRI-based techniques like diffusion tensor imaging (DTI) and proton magnetic resonance spectroscopy (1H-MRS), as well as nuclear medicine modalities like positron emission tomography (PET) and single photon emission tomography (SPECT) are being used to study brains of patients with ALS. Many previous MRI studies of ALS brain are limited either in methodology or information obtained being primarily qualitative, i.e. changes visible to the naked eye (macroscopic). This study employed both routine and novel MRI sequences to objectively assess gray and white matter pathology of the brain in ALS patients, including T2 relaxometry, DTI, and voxel based morphometry (VBM) of 3D high resolution T1-weighted images. DTI metrics showed significant (p< 0.05) changes in rostral extent of corticospinal tract (CST) in ALS patients with predominantly UMN symptoms and signs, and the ALS-dementia patients, whereas more caudal involvement was observed in ALS patients with classic findings of UMN and LMN d

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