Magnetic resonance imaging
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Comparative Study
Quantitative multi-modal functional MRI with blood oxygenation level dependent exponential decays adjusted for flow attenuated inversion recovery (BOLDED AFFAIR).
A magnetic resonance imaging (MRI) method is described that allows interleaved measurements of transverse (R(2)(*) and R(2)) and longitudinal (R(1)) relaxation rates of tissue water in conjunction with spin labeling. The image-contrasts are intrinsically blood oxygenation level dependent (BOLD) and cerebral blood flow (CBF) weighted, but each contrast is made quantitative by two echo time (TE) and inversion recovery time (TIR) acquisitions with gradient echo (GE) and spin echo (SE) weighted echo-planar imaging (EPI). The EPI data were acquired at 7 Tesla with nominal spatial resolution of 430 x 430 x 1000 microm(3) in rat brain in vivo. ⋯ The method is validated by comparison of multi-modal maps obtained by BOLDED AFFAIR (i.e., two TE and TIR values with GE and SE sequences) and conventional approach (i.e., multiple TE and TIR values with GE and SE sequences) during varied levels of whole brain activity. Preliminary functional data from a rat forepaw stimulation model demonstrate the feasibility of this method for functional MRI (fMRI) studies. It is expected that with appropriate precautions this method in conjunction with contrast agent-based MRI has great potential for quantitative fMRI studies of mammalian cortex.
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Comparative Study Clinical Trial
Ultrafast magnetic resonance imaging of the brain.
The purpose of this study was to compare the diagnostic efficacy of single shot fast spin echo sequence (SSh-FSE), and single shot GRASE-sequence (SSh-GRASE) to the conventional T(2)-weighted fast spin echo-sequence (T(2)-FSE) in the imaging of brain disorders. Thirty three patients with high signal intensity lesions on T(2)-weighted images (n = 28), or intracerebral hemorrhage (n = 5), were examined on a 1.0 T MR scanner, with 23 mT/m gradient strength. The scan time for the conventional T(2)-FSE-sequence was 2 min 57 s, the scan time for the single shot-FSE-, and single shot-GRASE-sequences was 11 sec, and 17 sec, respectively. ⋯ Physiologic ferritin as well as pathologic hemosiderin depositions were slightly darker and therefore better visible on SSh-GRASE than on SSh-FSE. Conventional T(2)-FSE showed significantly more artifacts. In conclusion, SSh-FSE and SSh-GRASE imaging can be used for rapid imaging of the brain in those patients who are claustrophobic or in patients with involuntary movements due to extrapyramidal disorders, as well as in children in whom anesthesia is contraindicated or sedation is not possible.
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Clinical Trial
Evaluation of Crohn's disease using half-fourier RARE and gadolinium-enhanced SGE sequences: initial results.
To assess the bowel changes in Crohn's disease, 11 consecutive patients underwent magnetic resonance imaging (MRI) study using T(2)-weighted half-Fourier rapid acquisition with relaxation enhancement (RARE) and gadolinium-enhanced standard and fat suppressed spoiled gradient echo (SGE) sequences. Comparison was made between MR findings of disease extent, severity, and complications and clinical data, endoscopic findings and/or surgical specimens in all patients. ⋯ Complications such as intraperitoneal (i. p.) abscess (2 patients), gastric outlet obstruction (1 patient), bowel obstruction (2 patients), and fistula formation (3 patient), were accurately shown. We conclude that T(2)-weighted half-Fourier RARE and gadolinium-enhanced fat suppressed SGE sequences are complementary techniques that possess different imaging features that are of value for assessing bowel changes in Crohn's disease.