Diffuse optical tomographic reconstruction using multifrequency data.

We investigated the use of multifrequency diffuse optical tomography (MF-DOT) data for the reconstruction of the optical parameters. The experiments were performed in a 63 mm diameter cylindrical phantom containing a 15 mm diameter cylindrical object. Modulation frequencies ranging from 110 MHz to 280 MHz were used in the phantom experiments changing the contrast in absorption of the object with respect to the phantom while keeping the scattering value the same.

Mild cognitive impairment: apparent diffusion coefficient in regional gray matter and white matter structures.

Purpose: To prospectively evaluate regional alterations in the apparent diffusion coefficient (ADC) of cortical gray and white matter and subcortical structures that are known to be involved in mild cognitive impairment (MCI).

Materials And Methods: Magnetic resonance (MR) imaging was performed in 13 patients with MCI (nine men, four women; mean age, 74 years +/- 6 [standard deviation]) and 13 healthy elderly control subjects (seven men, six women; mean age, 75 years +/- 4). This study was approved by the institutional review board and was HIPAA compliant.

Contrast and spatial resolution in MREIT using low amplitude current.

Magnetic resonance-electrical impedance tomography employs low amplitude currents injected or induced inside an object. The additional magnetic field due to these currents results in a phase in the MR images. In this study, a modified fast spin-echo sequence was used to measure this magnetic field, which is obtained by scaling the MR phase image.

Regional quantification of white matter hyperintensity in normal aging, mild cognitive impairment, and Alzheimer's disease.

Background/aims: A quantitative method was applied to measure the volume of white matter hyperintensity (WMH) in different brain regions of subjects with Alzheimer's disease (AD), mild cognitive impairment (MCI) and normal healthy age-matched controls, and the relationship between regional WMH and age and cognitive function was investigated.

Methods: Fifty-six subjects were included in this study, 27 AD, 15 MCI and 14 normal age-matched controls. A user-friendly software was developed for WMH quantification in frontal, temporal, and parieto-occipital lobes.

Vascular volume and blood-brain barrier permeability measured by dynamic contrast enhanced MRI in hippocampus and cerebellum of patients with MCI and normal controls.

Purpose: To measure the cerebrovascular volume and blood-brain barrier (BBB) permeability indices in hippocampus and cerebellum of patients with mild cognitive impairment (MCI) using dynamic contrast-enhanced MRI (DCE-MRI), and compare to that of normal controls.

Materials And Methods: A total of 11 MCI subjects and 11 healthy elderly controls participated in this prospective study. DCE-MRI was performed to measure the contrast enhancement kinetics.

Combined diffuse optical tomography (DOT) and MRI system for cancer imaging in small animals.

Recently, there has been a great amount of interest in developing multi-modality imaging techniques for oncologic research and clinical studies with the aim of obtaining complementary information and, thus, improving the detection and characterization of tumors. In this present work, the details of a combined MR-diffuse optical imaging system for dual-modality imaging of small animals are given. As a part of this effort, a multi-spectral frequency domain diffuse optical tomography system is integrated with an MRI system.

Resolution improvement in positron emission tomography using anatomical Magnetic Resonance Imaging.

An ideal imaging system should provide information with high-sensitivity, high spatial, and temporal resolution. Unfortunately, it is not possible to satisfy all of these desired features in a single modality. In this paper, we discuss methods to improve the spatial resolution in positron emission imaging (PET) using a priori information from Magnetic Resonance Imaging (MRI).

Design and implementation of a multifrequency near-infrared diffuse optical tomography system.

The design and implementation of a multifrequency and multispectral diffuse optical tomography system is described. Four wavelengths are utilized: 665, 785, 808, and 830 nm. The system is based on a network analyzer, which provides rf modulation signals for the laser diodes, as well as measures the amplitude and the phase of the detected signals.