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Biomedical subjects

H R Griffith

Publications and source records attributed to H R Griffith.

7 recordsLinked to original sources
PubMed2006

Implementation of talairach atlas based automated brain segmentation for radiation therapy dosimetry.

Radiotherapy for brain cancer inevitably results in irradiation of uninvolved brain. While it has been demonstrated that irradiation of the brain can result in cognitive deficits, dose-volume relationships are not well established. There is little work correlating a particular cognitive deficit with dose received by the region of the brain responsible for the specific cognitive function. One obstacle to such studies is that identification of brain anatomy is both labor intensive and dependent on the individual performing the segmentation. Automatic segmentation has the potential to be both efficient and consistent. Brains2 is a software package developed by the University of Iowa for MRI volumetric studies. It utilizes MR images, the Talairach atlas, and an artificial neural network (ANN) to segment brain images into substructures in a standardized manner. We have developed a software package, Brains2DICOM, that converts the regions of interest identified by Brains2 into a DICOM radiotherapy structure set. The structure set can be imported into a treatment planning system for dosimetry. We demonstrated the utility of Brains2DICOM using a test case, a 34-year-old man with diffuse astrocytoma treated with three-dimensional conformal radiotherapy. Brains2 successfully applied the Talairach atlas to identify the right and left frontal, parietal, temporal, occipital, subcortical, and cerebellum regions. Brains2 was not successful in applying the ANN to identify small structures, such as the hippocampus and caudate. Further work is necessary to revise the ANN or to develop new methods for identification of small structures in the presence of disease and radiation induced changes. The segmented regions-of-interest were transferred to our commercial treatment planning system using DICOM and dose-volume histograms were constructed. This method will facilitate the acquisition of data necessary for the development of normal tissue complication probability (NTCP) models that assess the probability of cognitive complications secondary to radiotherapy for intracranial and head and neck neoplasms.

Adult↗
PubMed2005

Medical decision-making in neurodegenerative disease: mild AD and PD with cognitive impairment.

The authors compared medical decision-making capacity in patients with mild Alzheimer disease (AD), Parkinson disease (PD) with cognitive impairment, and older controls. Relative to controls and patients with PD, patients with AD were impaired on the consent ability of understanding the medical treatment situation and choices. Patients with PD were impaired on the consent ability of electing a treatment choice.

Aged↗
PubMed2003

Impaired financial abilities in mild cognitive impairment: a direct assessment approach.

OBJECTIVES: To assess financial capacity in patients with mild cognitive impairment (MCI) using a standardized psychometric capacity measure. METHODS: Participants were 21 cognitively normal older controls, 21 patients with amnestic MCI, and 22 patients with mild AD. The Financial Capacity Instrument (FCI), a psychometric capacity measure consisting of 18 financial ability tests (tasks), 9 domains (activities), and 2 total scores, was administered to participants along with a battery of neuropsychological tests sensitive to dementia. Group differences were examined on the neuropsychological and financial capacity variables. RESULTS: Relative to controls, the MCI group demonstrated impairments in episodic memory, and also semantic knowledge, executive function, written arithmetic, and spatial attention. MCI participants demonstrated impairments in FCI domains of conceptual knowledge, cash transactions, bank statement management, and bill payment, and in overall financial capacity. The control and MCI groups performed significantly better than patients with AD on most financial capacity and cognitive measures. CONCLUSIONS: On direct assessment, patients with amnestic MCI as a group demonstrate impairments across a range of financial abilities. These impairments are mild and may only apply to a subset of patients with MCI. However, existing diagnostic criteria for MCI should be applied flexibly to include mild impairments in higher order activities of daily life such as financial capacity.

Aged↗
PubMed2000

Preoperative FDG-PET temporal lobe hypometabolism and verbal memory after temporal lobectomy.

OBJECTIVE: To examine the relationship of preoperative fluorodeoxyglucose (FDG)-PET asymmetry in temporal lobe metabolism and memory outcome after anterior temporal lobectomy (ATL). METHODS: In a university-based epilepsy surgery center, 60 ATL patients (27 left, 33 right) were divided into two groups: no/mild (n = 21) or moderate/ severe (n = 39) asymmetry in temporal lobe hypometabolism as determined by FDG-PET. All patients were nonretarded, at least 18 years of age, left-hemisphere speech dominant, without MRI abnormalities other than hippocampal atrophy, and with unilateral temporal lobe origin of intractable complex partial seizures. Neuropsychological measures of intelligence and verbal and visual memory function were assessed preoperatively and 6 months postoperatively. RESULTS: Left ATL patients with no/mild asymmetry in FDG-PET temporal lobe metabolism exhibited significantly greater verbal memory decline compared with left ATL patients with moderate/severe hypometabolism. There was no significant relationship between PET asymmetry and pre- to postsurgical IQ change. No significant relationship was observed between extent of PET hypometabolism and memory outcome for right ATL patients. CONCLUSIONS: FDG-PET asymmetry can be added to the preoperative clinical markers that appear useful in predicting verbal memory decline after left ATL.

Adult↗
PubMed1997

The flexible use of multiple cue relationships in spatial navigation: a comparison of water maze performance following hippocampal, medial septal, prefrontal cortex, or posterior parietal cortex lesions.

Rats prepared with lesions of the prefrontal cortex, posterior parietal cortex, hippocampus, or medial septal area were tested for acquisition of a number of variations of the open-field water maze using a version of place learning assessment described by Eichenbaum, Stewart, and Morris (1991). Specifically, the individual role of the aforementioned cortical and subcortical structures in tasks with differing representational demands on navigation were assessed. The results suggest that the sham-operated control, posterior parietal cortex-lesioned rats, and medial septal area-lesioned rats were able to navigate effectively under changing task conditions. Conversely, the navigational performances of the prefrontal cortex- and hippocampal formation-lesioned rats were impaired when task demands changed. The results are discussed in terms of the flexible use of multiple distal cues to guide navigation and the resulting loss of this flexibility after lesions to either the prefrontal cortex or the hippocampus.

Animals↗