Journal of magnetic resonance imaging : JMRI
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The suppression of signal from fat constitutes a basic requirement in many applications of magnetic resonance imaging. To date, this is predominantly achieved during data acquisition, using fat saturation, inversion recovery, or water excitation methods. Postponing the separation of signal from water and fat until image reconstruction holds the promise of resolving some of the problems associated with these methods, such as failure in the presence of field inhomogeneities or contrast agents. ⋯ The basic principle underlying these so-called Dixon methods is introduced, and some fundamental implementations of the required chemical shift encoding in the acquisition and the subsequent water-fat separation in the reconstruction are described. Practical issues, such as the selection of key parameters and the appearance of typical artifacts, are illustrated, and a broad range of applications is demonstrated, including abdominal, cardiovascular, and musculoskeletal imaging. Finally, advantages and disadvantages of these Dixon methods are summarized, and emerging opportunities arising from the availability of information on the amount and distribution of fat are discussed.
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J Magn Reson Imaging · Aug 2014
Cerebrovascular reactivity mapping in patients with low grade gliomas undergoing presurgical sensorimotor mapping with BOLD fMRI.
(i) to validate blood oxygenation level dependent (BOLD) breathhold cerebrovascular reactivity (BH CVR) mapping as an effective technique for potential detection of neurovascular uncoupling (NVU) in a cohort of patients with perirolandic low grade gliomas undergoing presurgical functional MRI (fMRI) for sensorimotor mapping, and (ii) to determine whether NVU potential, as assessed by BH CVR mapping, is prevalent in this tumor group. ⋯ Presurgical sensorimotor fMRI mapping can be affected by NVU-related false negative activation in low grade gliomas (76% of analyzed tasks).
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J Magn Reson Imaging · Aug 2014
Comparative StudyDiagnostic accuracy of dynamic gadoxetic-acid-enhanced MRI and PET/CT compared in patients with liver metastases from neuroendocrine neoplasms.
To evaluate the diagnostic accuracy of dynamic-contrast-enhanced (DCE) MRI in comparison to both (18)F-FDG- and (68)Ga-DOTATATE-PET/CT in patients with liver metastases of neuroendocrine neoplasms (NEN). ⋯ Both PET/CT parameters and DCE-MRI perfusion parameters show a high diagnostic accuracy in the distinction between liver metastases and liver tissue. Our data suggest that both modalities provide complementary information.
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J Magn Reson Imaging · Aug 2014
Decline of fiber tract integrity over the adult age range: a diffusion spectrum imaging study.
We applied a novel diffusion spectrum imaging (DSI) acquisition to determine associations between aging and subcortical fiber tract integrity. ⋯ Our data suggest that normal aging leads to a regionally specific decline in fiber tract integrity. DSI may become a useful biomarker in healthy and pathological aging.
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J Magn Reson Imaging · Aug 2014
Liver lesion conspicuity during real-time MR-guided radiofrequency applicator placement using spoiled gradient echo and balanced steady-state free precession imaging.
To retrospectively evaluate the conspicuity of liver lesions in a fluoroscopic spoiled gradient echo (GRE) and a balanced steady-state free precession (SSFP) magnetic resonance imaging (MRI) sequence. ⋯ MR fluoroscopy using GRE and SSFP contrast enabled real-time detectability of 80% of the liver lesions.