Topics in magnetic resonance imaging : TMRI
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Top Magn Reson Imaging · Apr 2007
ReviewWhole-body contrast-enhanced magnetic resonance angiography: new advances at 3.0 T.
During the past decade, technical improvements and numerous advances in scanner hardware and software have significantly improved image quality, speed, and reliability of 3-dimensional (3-D) contrast-enhanced magnetic resonance angiography (CE-MRA). The accuracy of CE-MRA is now comparable with that of computed tomography angiography or even conventional catheter angiography. Peripheral vascular disease (PVD) accounts for 50,000 to 60,000 cases of percutaneous transluminal angioplasty and for about 100,000 cases of amputation annually in the United States. ⋯ The lack of ionizing radiation and the use of contrast agent with relatively small potential nephrotoxicity in population of PVD with high prevalence of renal impairment are the appealing features for broad acceptance of CE-MRA in initial diagnosis and repeated follow-up studies of patients with PVD. The minimum anatomical coverage for evaluation of PVD comprises the aortic bifurcation to the ankles; however, because of the systemic nature of atherosclerosis hypertension, renal or cerebrovascular disease frequently coexist. Thus, many clinicians regard evaluation of the whole-body arterial vasculature as desirable.
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Top Magn Reson Imaging · Apr 2007
ReviewHigh-field-strength magnetic resonance: potential and limits.
To expatiate on the possible advantages and disadvantages of high magnetic field strengths for magnetic resonance imaging and, in particular, for magnetic resonance angiography. ⋯ The drive toward higher field strengths, both for the purpose of fundamental research and for clinical diagnostic imaging, is likely to continue. New applications using the unique properties of high field strength will almost certainly emerge as researchers gain more experience. The ultimate limiting factor is likely to be the physiological effects at high field strengths. However, this limit seems to lie at field strengths higher than 7 T because early experience shows good tolerance of 7 T examinations.
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Top Magn Reson Imaging · Feb 2007
ReviewAdvances in magnetic resonance neuroimaging techniques in the evaluation of neonatal encephalopathy.
Magnetic resonance (MR) imaging has become an essential tool in the evaluation of neonatal encephalopathy. Magnetic resonance-compatible neonatal incubators allow sick neonates to be transported to the MR scanner, and neonatal head coils can improve signal-to-noise ratio, critical for advanced MR imaging techniques. Refinement of conventional imaging techniques include the use of PROPELLER techniques for motion correction. ⋯ Knowledge of normal developmental changes in MR spectroscopy metabolite concentration and diffusion tensor metrics is essential to interpret pathological cases. Perfusion MR and functional MR can provide additional physiological information. Both MR spectroscopy and diffusion tensor imaging can provide additional information in the differential of neonatal encephalopathy, including perinatal white matter injury, hypoxic-ischemic brain injury, metabolic disease, infection, and birth injury.
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Top Magn Reson Imaging · Feb 2007
ReviewMacrocephaly, increased intracranial pressure, and hydrocephalus in the infant and young child.
Macrocephaly, increased intracranial pressure, and hydrocephalus are common related conditions that lead to cross-sectional imaging of the infant and young child. Imaging plays a central role in establishing the diagnosis and guiding disposition and treatment of these patients. In this review, a general overview is provided, and the more common causes of hydrocephalus are presented, including posthemorrhage, postinfection, developmental malformations, and masses. Imaging guidelines are also outlined for initial evaluation and follow-up, along with a discussion of the imaging features of shunt malfunction.
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Top Magn Reson Imaging · Dec 2006
ReviewMagnetic resonance imaging of abdominal pain during pregnancy.
The objective of this review is to demonstrate magnetic resonance imaging as an important adjunct to ultrasound and computed tomography in the evaluation of the pregnant patient with abdominal pain. With the advent of ultrafast T2-weighted pulse sequences, fetal and bowel motion cause minimal artifact on the images. ⋯ T1-weighted gradient echo images with and without fat saturation are useful for identifying blood and fat, especially in the case of adnexal masses. Gadolinium-diethylenetriamine pentaacetic acid is rarely used to diagnose inflammatory or obstructive disease and is reserved for those patients with suspected malignancies.