Journal of magnetic resonance imaging : JMRI
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J Magn Reson Imaging · Oct 2004
ReviewFunctional MRI of the lung using hyperpolarized 3-helium gas.
Lung imaging has traditionally relied on x-ray methods, since proton MRI is limited to some extent by low proton density in the lung parenchyma and static field inhomogeneities in the chest. The relatively recent introduction of MRI of hyperpolarized noble gases has led to a rapidly evolving field of pulmonary MRI, revealing functional information of the lungs, which were hitherto unattainable. This review article briefly describes the physical background of the technology, and subsequently focuses on its clinical applications. Four different techniques that have been used in various human investigations are discussed: ventilation distribution, ventilation dynamics, and small airway evaluation using diffusion imaging and oxygen uptake assessment.
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J Magn Reson Imaging · Oct 2004
Interleaved echo-planar imaging for fast multiplanar magnetic resonance temperature imaging of ultrasound thermal ablation therapy.
To develop a multiplanar magnetic resonance temperature imaging (MRTI) technique based on interleaved gradient-echo echo-planar imaging (EPI), verify in phantom, develop software tools to process and display data on a clinical scanner in near real-time, and demonstrate feasibility to monitor ultrasound thermal ablation therapy in vivo. ⋯ Multi-planar MRTI allowed progression of thermal damage to be monitored and treatment parameters adjusted in near real-time (less than five second delay). EPI MRTI is an effective multi-planar monitoring method during ultrasound thermal ablation procedures.
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J Magn Reson Imaging · Oct 2004
An accurate and robust method for unsupervised assessment of abdominal fat by MRI.
To describe and evaluate an automatic and unsupervised method for assessing the quantity and distribution of abdominal adipose tissue by MRI. ⋯ The results obtained demonstrate that the proposed method can provide the volume of subcutaneous adipose tissue, visceral adipose tissue, global adipose tissue, and the ratio between subcutaneous and visceral fat in an unsupervised and effective manner.
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J Magn Reson Imaging · Oct 2004
Diffusion tensor eigenvector directional color imaging patterns in the evaluation of cerebral white matter tracts altered by tumor.
To categorize the varied appearances of tumor-altered white matter (WM) tracts on diffusion tensor eigenvector directional color maps. ⋯ Tumor alteration of WM tracts tends to produce one of four patterns on FA and directional color maps. Clinical application of these patterns must await further study.
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J Magn Reson Imaging · Oct 2004
On flow effects in balanced steady-state free precession imaging: pictorial description, parameter dependence, and clinical implications.
To present a pictorial description of the origin of flow effects in balanced steady-state free precession (SSFP) imaging that can result in considerable frequency offset-dependent signal changes originating from outflow of spins that can still contribute to the total SSFP signal (out-of-slice contributions), to analyze the parameter dependence and slice broadening associated with outflow effects, and to illustrate clinical implications such as frequency offset-dependent flow artifacts and spatial misencoding. ⋯ Flow-related signal changes in SSFP imaging exhibit highly complex parameter dependence, which predominantly has to be associated with frequency offset-dependent outflow effects and a resulting broadening of the slice thickness.