scholarly journals High isotropic resolution magnetic resonance imaging of the mandibular canal at 1.5 T: a comparison of gradient and spin echo sequences

2017 ◽  
Vol 46 (2) ◽  
pp. 20160268 ◽  
Author(s):  
Jakob Kreutner ◽  
Andreas Hopfgartner ◽  
Daniel Weber ◽  
Julian Boldt ◽  
Kurt Rottner ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Spin Echo ◽  
Mandibular Canal ◽  
Resonance Imaging ◽  
Isotropic Resolution ◽  
Spin Echo Sequences

scholarly journals High-Resolution CMRO2 Mapping in Rat Cortex: A Multiparametric Approach to Calibration of BOLD Image Contrast at 7 Tesla

2000 ◽  
Vol 20 (5) ◽  
pp. 847-860 ◽  
Author(s):  
Ikuhiro Kida ◽  
Richard P. Kennan ◽  
Douglas L. Rothman ◽  
Kevin L. Behar ◽  
Fahmeed Hyder
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Spin Echo ◽  
7 Tesla ◽  
Relaxation Rates ◽  
Resonance Imaging ◽  
Gradient Echo ◽  
Transverse Relaxation ◽  
Physiologic Parameters ◽  
Spin Echo Sequences

The blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) method, which is sensitive to vascular paramagnetic deoxyhemoglobin, is dependent on regional values of cerebral metabolic rate of oxygen utilization (CMRO2), blood flow (CBF), and volume (CBV). Induced changes in deoxyhemoglobin function as an endogenous contrast agent, which in turn affects the transverse relaxation rates of tissue water that can be measured by gradient-echo and spin-echo sequences in BOLD fMRI. The purpose here was to define the quantitative relation between BOLD signal change and underlying physiologic parameters. To this end, magnetic resonance imaging and spectroscopy methods were used to measure CBF, CMRO2, CBV, and relaxation rates (with gradient-echo and spin-echo sequences) at 7 Tesla in rat sensorimotor cortex, where cerebral activity was altered pharmacologically within the autoregulatory range. The changes in tissue transverse relaxation rates were negatively and linearly correlated with changes in CBF, CMRO2, and CBV. The multiparametric measurements revealed that CBF and CMRO2 are the dominant physiologic parameters that modulate the BOLD fMRI signal, where the ratios of (ΔCMRO2/CMRO2)/(ΔCBF/CBF) and (ΔCBV/CBV)/(ΔCBF/CBF) were 0.86 ± 0.02 and 0.03 ± 0.02, respectively. The calibrated BOLD signals (spatial resolution of 48 μL) from gradient-echo and spin-echo sequences were used to predict changes in CMRO2 using measured changes in CBF, CBV, and transverse relaxation rates. The excellent agreement between measured and predicted values for changes in CMRO2 provides experimental support of the current theory of the BOLD phenomenon. In gradient-echo sequences, BOLD contrast is affected by reversible processes such as static inhomogeneities and slow diffusion, whereas in spin-echo sequences these effects are refocused and are mainly altered by extravascular spin diffusion. This study provides steps by which multiparametric MRI measurements can be used to obtain high-spatial resolution CMRO2 maps.

Non-invasive temperature imaging of muscles with magnetic resonance imaging using spin-echo sequences

1998 ◽  
Vol 36 (6) ◽  
pp. 673-678 ◽  
Author(s):  
E. Mietzsch ◽  
M. Koch ◽  
M. Schaldach ◽  
J. Werner ◽  
B. Bellenberg ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Spin Echo ◽  
Resonance Imaging ◽  
Temperature Imaging ◽  
Non Invasive ◽  
Spin Echo Sequences

Nichtinvasive Beurteilung aortokoronarer Venenbrücken mit Kernspintomographie

1989 ◽  
Vol 28 (06) ◽  
pp. 234-242 ◽  
Author(s):  
U. Sechtem ◽  
Sabine Langkamp ◽  
M. Jungehülsing ◽  
H. H. Hilger ◽  
H. Schicha ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Coronary Artery ◽  
Magnetic Resonance ◽  
Coronary Artery Bypass ◽  
Spin Echo ◽  
Artery Bypass ◽  
Graft Patency ◽  
Coronary Artery Bypass Grafts ◽  
Resonance Imaging ◽  
Low Sensitivity

Fortyfour patients with recent cardiac catheterization because of recurrent chest pain after coronary artery bypass surgery were studied by magnetic resonance imaging to evaluate graft patency. To assess the efficacy of this non-invasive method 92 coronary artery bypass grafts were examined by the spin-echo technique. ECG-gated transversal sections were acquired between the diaphragm and the aortic arch. The specificity of magnetic resonance imaging was 83% (48/58) for patent grafts. However, the sensitivity in the detection of occluded bypasses was only 56% (19/34). Despite the good specificity, clinical applications of this method are limited because of its low sensitivity.

Ultra high resolution nonenhanced fast spin echo magnetic resonance imaging: Cost-effective screening for acoustic neuroma in patients with sudden sensorineural hearing loss

1998 ◽  
Vol 119 (4) ◽  
pp. 364-369 ◽  
Author(s):  
Robert L. Daniels ◽  
Clough Shelton ◽  
H. Ric Harnsberger
Keyword(s):  
Magnetic Resonance Imaging ◽  
Hearing Loss ◽  
Magnetic Resonance ◽  
Sensorineural Hearing Loss ◽  
Acoustic Neuroma ◽  
Spin Echo ◽  
Sudden Sensorineural Hearing Loss ◽  
Fast Spin Echo ◽  
Resonance Imaging ◽  
Fast Spin

The financial burden for the evaluation of patients for acoustic neuroma in an otolaryngology practice is substantial. Patients with sudden sensorineural hearing loss represent a portion of that population seen with unilateral, asymmetric auditory symptoms who require investigation for acoustic neuroma. For these patients, gadolinium-enhanced magnetic resonance imaging is the diagnostic gold standard. Auditory brain stem response testing has been used in the past as a screening test for acoustic neuroma, but its apparent sensitivity has fallen as the ability to image smaller acoustic neuromas has improved. Fast spin echo magnetic resonance imaging techniques without gadolinium have been shown to be as effective in the detection of acoustic neuroma as contrast-enhanced magnetic resonance imaging. Limited nonenhanced fast spin echo magnetic resonance imaging now provides an inexpensive alternative for high-resolution imaging of the internal auditory canal and cerebellopontine angle. Fast spin echo magnetic resonance imaging can now be done at a cost approximating auditory brain stem response testing while providing the anatomic information of contrast-enhanced magnetic resonance imaging. Cost analysis was done in the cases of 58 patients with sudden sensorineural hearing loss by comparing the costs for routine workup and screening of acoustic neuroma with the cost of fast spin echo magnetic resonance imaging with the use of screening protocols based on literature review. The potential cost savings of evaluating patients with sudden sensorineural hearing loss with fast spin echo magnetic resonance imaging for acoustic neuroma was substantial, with a 54% reduction in screening costs. In an era of medical economic scrutiny, fast spin echo magnetic resonance imaging has become the most cost-effective method to screen suspected cases of acoustic tumors at our institution by improving existing technology while reducing the cost of providing that technology and eliminating charges for impedance audiometry, auditory brain stem response testing, and contrast-enhanced magnetic resonance imaging.

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