0000000000354414
AUTHOR
Jaroslav Tintera
The effects of linearly increasing flip angles on 3D inflow MR angiography
As recently demonstrated, spin saturation effects in 3D time-of-flight (TOF) MR angiography (MRA) can be reduced by using RF pulses with linearly increasing flip angles (ramp pulses) in the main direction of flow. We developed a model for calculating the signal distribution of proton flow within the excitation volume (slab) for different ramp slopes and compared the results with the measured distribution for the lower-leg arteries. The ramp pulses were generated using the Fourier transformation of the desired excitation profiles. With a bandwidth of 6 kHz and a pulse length of 2.56 ms satisfactory ramps with variable slopes were generated and applied in a standard flow-compensated 3D FISP s…
PROTON MAGNETIC RESONANCE SPECTROSCOPY IN DEMENTIA OF ALZHEIMER TYPE
Reduced N-acetyl aspartate (NAA) and increased myo-inositol (MI) levels have been reported in patients with dementia of Alzheimer type (DAT) in comparison with controls. We wished to assess the validity of these findings and to evaluate possible correlations of metabolite proportions with cognitive dysfunction in DAT. Twelve patients with DAT and 10 healthy age-matched controls were included. The severity of dementia was assessed using different scales including the Mini-Mental State Examination. MRS was performed with a conventional 1.5 Tesla scanner in a single voxel in the centrum semi-ovale (TE = 30 ms or TE = 136 ms; TR = 1500 ms). The evaluation of MRS results was limited by low inter…
Microcirculation after cerebral venous occlusions as assessed by laser Doppler scanning.
✓ Research on cerebral venous circulation disturbances (CVCDs) has been limited partly by the paucity of animal models that produce consistent venous infarction. Occlusion of two adjacent cortical veins in rats by means of a photochemical thrombotic technique provides a minimally invasive, clinically relevant, and reproducible model suited to study the pathophysiology of CVCDs. In this study, the effects of venous occlusion on regional cortical blood flow and the brain damage that ensues were evaluated. Cortical vein occlusion was induced by photoactivation of rose bengal via 100-µm fiberoptic illumination. The cerebral venous flow pattern was examined using fluorescence angiography until 9…