ABSTRACT
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ABSTRACT
This study was conducted to investigate the metabolic changes in the motor and motor association cortices following axonal injury in the internal capsule that was caused by deep intracerebral hematoma. Using proton magnetic resonance spectroscopy (1H MRS), the authors studied the primary motor cortices (M-1) and sup-plementary motor areas (SMA) of 9 hemiparetic patients with documentable hemi-paresis of varying severity, and we studied 10 normal volunteers as controls. To measure the M-1 and SMA biochemical changes, 4 separate single volumes of inter-est(VOIs) were located bilaterally in the affected and unaffected hemisphere (AH and UH).1H MRS provided a neuronal and axonal viability index by measuring levels of N-acetylaspartate (NAA) and creatine/phosphocreatine (Cr). The M-1/SMA NAA/Cr ratios of the AH and UH in patients, and the AH and normal volunteers were com-pared. The NAA/Cr ratios of the M-1 and SMA in AH, and the SMA in UH were sig-nificantly lower than those of normal volunteers. These 1H MRS findings indicate that axonal injury in the descending motor pathway at the level of internal capsule could induce metabolic changes in the higher centers of the motor pathway.
Subject(s)
Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Aspartic Acid/analogs & derivatives , Basal Ganglia Hemorrhage/metabolism , Creatine/metabolism , Magnetic Resonance Spectroscopy , Motor Cortex/metabolism , Paresis/metabolism , Phosphocreatine/metabolism , Protons , Pyramidal Tracts/metabolismABSTRACT
OBJECTIVE: To determine, using proton magnetic resonance spectroscopy (1H MRS) whether thalamotomy in patients with Parkinson's disease gives rise to significant changes in regional brain metabolism. MATERIALS AND METHODS: Fifteen patients each underwent stereotactic thalamotomy for the control of medically refractory parkinsonian tremor. Single-voxel 1H MRS was performed on a 1.5T unit using a STEAM sequence (TR/TM/TE, 2000/14/20 msec), and spectra were obtained from substantia nigra, thalamus and putamen areas, with volumes of interest of 7-8ml, before and after thalamotomy. NAA/Cho, NAA/Cr and Cho/Cr metabolite ratios were calculated from relative peak area measurements, and any changes were recorded and assessed. RESULTS: In the substantia nigra and thalamus, NAA/Cho ratios were generally low. In the substantia nigra of 80% of patients (12/15) who showed clinical improvement, decreased NAA/Cho ratios were observed in selected voxels after thalamic surgery (p < 0.05). In the thalamus of 67% of such patients (10/15), significant decreases were also noted (p < 0.05). CONCLUSION: Our results suggest that the NAA/Cho ratio may be a valuable criterion for the evaluation of Parkinson's disease patients who show clinical improvement following surgery. By highlighting variations in this ratio, 1H MRS may help lead to a better understanding of the pathophysiologic processes occurring in those with Parkinson's disease.
Subject(s)
Adult , Aged , Female , Humans , Male , Aspartic Acid/analogs & derivatives , Brain/metabolism , Choline/metabolism , Magnetic Resonance Imaging , Magnetic Resonance Spectroscopy , Middle Aged , Parkinson Disease/metabolism , Protons , Putamen/metabolism , Substantia Nigra/metabolism , Thalamus/metabolismABSTRACT
PURPOSE: Within a clinically acceptable time frame, we obtained the high resolution MR images of the human brain, knee, foot and wrist from 3T whole-body MRI system which was equipped with the world first 3T active shield magnet. MATERIALS AND METHODS: Spin echo (SE) and Fast Spin Echo (FSE) images were obtained from the human brain, knee, foot and wrist of normal subjects using a homemade birdcage and transverse electromagnetic (TEM) resonators operating in quadrature and tuned to 128 MHz. For acquisition of MR images of knee, foot and wrist, we employed a homemade saddle shaped RF coil. Typical common acquisition parameters were as follows: matrix= 512x512, field of view (FOV) = 20 cm, slice thickness = 3 mm, number of excitations (NEX) = 1. For T1-weighted MR images, we used TR= 500 ms, TE = 10 or 17.4 ms. For T2-weighted MR images, we used TR=4000 ms, TE = 108 ms. RESULTS: Signal to noise ratio (SNR) of 3T system was measured 2.7 times greater than that of prevalent 1.5T system. MR images obtained from 3T system revealed numerous small venous structures throughout the image plane and provided reasonable delineation between gray and white matter. CONCLUSION: The present results demonstrate that the MR images from 3T system could provide better diagnostic quality of resolution and sensitivity than those of 1.5T system. The elevated SNR observed in the 3T high field magnetic resonance imaging can be utilized to acquire images with a level of resolution approaching the microscopic structural level under in vivo conditions. These images represent a significant advance in our ability to examine small anatomical features with noninvasive imaging methods.