Robert J. Ogg

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For the last century, there has been great physiological interest in brain iron and its role in brain function and disease. It is well known that iron accumulates in the brain for people with Huntington's disease, Parkinson's disease, Alzheimer's disease, multiple sclerosis, chronic hemorrhage, cerebral infarction, anemia, thalassemia, hemochromatosis,(More)
Medulloblastoma encompasses a collection of clinically and molecularly diverse tumour subtypes that together comprise the most common malignant childhood brain tumour. These tumours are thought to arise within the cerebellum, with approximately 25% originating from granule neuron precursor cells (GNPCs) after aberrant activation of the Sonic Hedgehog(More)
The purpose of this study was to investigate the relationship between the magnetic susceptibility of brain tissue and iron concentration. Phase shifts in gradient-echo images (TE = 60 ms) were measured in 21 human subjects, (age 0.7-45 years) and compared with published values of regional brain iron concentration. Phase was correlated with brain iron(More)
Posterior fossa syndrome is characterized by cerebellar dysfunction, oromotor/oculomotor apraxia, emotional lability and mutism in patients after infratentorial injury. The underlying neuroanatomical substrates of posterior fossa syndrome are unknown, but dentatothalamocortical tracts have been implicated. We used pre- and postoperative neuroimaging to(More)
Conventional MRI (cMRI) has shown that brain abnormalities without clinical stroke can manifest in patients with sickle cell disease (SCD). We used quantitative MRI (qMRI) and psychometric testing to determine whether brain abnormalities can also be present in patients with SCD who appear normal on cMRI. Patients 4 years of age and older with no clinical(More)
Suppression of the water signal during 1H magnetic resonance spectroscopy by repeated sequences of a frequency-selective radiofrequency pulse and a gradient dephasing pulse requires nulling of the longitudinal component of the water magnetization and is therefore affected by T1 relaxation, RF-pulse flip angles (which depend on B1), and sequence timing. In(More)
We introduce a fast and robust spatial-spectral encoding method, which enables acquisition of high resolution short echo time (13 ms) proton spectroscopic images from human brain with acquisition times as short as 64 s when using surface coils. The encoding scheme, which was implemented on a clinical 1.5 Tesla whole body scanner, is a modification of an(More)
Age-related changes in brain T1 from 115 healthy subjects (range, 4.5-71.9 yr) were analyzed in relation to published regional brain iron concentration in cortex, caudate, putamen, and frontal white matter. The relaxation rate in these structures was linear with respect to iron concentration (P < 0.001). The iron relaxivity, k1 (s(-1)/mg iron/g wet weight),(More)
Functional magnetic resonance imaging (fMRI) was performed in 30 healthy adults to identify the location, magnitude, and extent of activation in brain regions that are engaged during the performance of Conners' Continuous Performance Test (CPT). Performance on the task during fMRI was highly correlated with performance on the standard Conners' CPT in the(More)
Children treated with cranial irradiation for brain tumors have reduced white matter volume and deficits in reading ability. This study prospectively examined the relationship between reading and white matter integrity within this patient group. Patients (n = 54) were treated with post-surgical radiation followed by 4 cycles of high-dose chemotherapy with(More)