Alongside the two conventional unenhanced magnetic resonance (MR) angiographic techniques, namely time-of-flight and phase-contrast MR angiography, several novel techniques have since been developed, including electrocardiograph (ECG)-gated fast spin echo (FSE), steady-state free precession (SSFP), and arterial spin labeling. These techniques are increasingly being used to avoid severe complications caused by contrast materials, such as iodinated contrast material-induced nephropathy and gadolinium-induced nephrogenic systemic fibrosis. However, image acquisition and interpretation with these techniques are more complicated than with contrast-enhanced MR angiography because of numerous types of artifacts. Appropriate use of these techniques can allow diagnosis of vascular diseases in patients with chronic kidney disease without using contrast materials. For example, time-of-flight angiography is the main technique for evaluating intracranial arteries. Phase-contrast imaging is increasingly being used for physiologic evaluation rather than morphologic evaluation. Meanwhile, ECG-gated FSE MR angiography can show peripheral arteries in more detail. SSFP MR angiography with or without arterial spin labeling can provide high-resolution images of blood vessels including renal arteries, the aorta, and coronary arteries. Black-blood imaging is also used to evaluate vessel walls and intravascular abnormalities including plaque, dissection, and thrombi. The authors review the principles of the currently available unenhanced MR angiographic techniques, along with their advantages and limitations, and describe their clinical applications. This article should help readers select the most appropriate unenhanced MR angiographic technique to assess vascular diseases in patients with chronic kidney disease. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.312105075/-/DC1.
Purpose:To confirm the superiority of the navigator-triggered prospective acquisition correction (PACE) technique over the conventional respiratory-triggered (RESP) technique, something that has been perceived experimentally but without definite evidence, for free-breathing three-dimensional (3D) magnetic resonance cholangiopancreatography (MRCP) using healthy volunteers.
Materials and Methods:Free-breathing 3D turbo spinecho MRCP using both PACE and RESP techniques were prospectively performed on 25 healthy volunteers. Quantitative analyses of acquisition time, signal-to-noise ratio, contrast-to-noise ratio, and contour sharpness index of each segment of the pancreaticobiliary tree were compared using the paired t-test. Qualitative analyses on a five-point scale (1, excellent; 5, poor) scored by two independent radiologists were compared using the Wilcoxon signed-rank test.
Results:The subjective image quality and contour sharpness index of each segment of the PACE technique were found to be significantly better than those for RESP (P Ͻ 0.05). No significant difference was observed with regard to signal-to-noise and contrast-to-noise ratios except for the pancreatic duct. No significant difference in acquisition times between PACE and RESP techniques was observed.
Conclusion:We confirmed the superiority of the image quality of the PACE technique compared to conventional RESP technique for free-breathing 3D MRCP in healthy volunteers.
A 33-year-old man had systemic lupus erythematosus (SLE) with anticardiolipin antibody. At the age of 40 years, he experienced bilateral hearing deterioration. The three-dimensional fluid-attenuated inversion recovery of magnetic resonance imaging showed high signals bilaterally in the cochlea and vestibule. He was diagnosed with bilateral inner ear hemorrhage on the basis of the presence of anticardiolipin antibody. This is the first published case of inner ear hemorrhage in a patient with SLE. Our findings suggest that inner ear hemorrhage is associated with hearing deterioration in some patients with SLE.
Three-dimensional, fluid-attenuated inversion recovery (3D-FLAIR) of magnetic resonance imaging (MRI) has recently been developed to detect hemorrhage or high concentrations of protein. We present a patient with Ramsay Hunt syndrome, in whom high signals in the cochlear and vestibular apparatus were identified with 3D-FLAIR. The high signal areas in 3D-FLAIR were not detected by T1- and T2-weighted MRI in this case. This is the first report of high concentrations of protein in the inner ear in Ramsay Hunt syndrome using 3D-FLAIR, and suggests that high concentrations of protein in the inner ear are associated with hearing deterioration in some patients with Ramsay Hunt syndrome. 3D-FLAIR could be a useful diagnostic tool in the early stages of Ramsay Hunt syndrome.
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