Investigative radiology
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Investigative radiology · May 2014
Ultrahigh-resolution imaging of the human brain with phase-cycled balanced steady-state free precession at 7 T.
The objectives of this study were to acquire ultra-high resolution images of the brain using balanced steady-state free precession (bSSFP) at 7 T and to identify the potential utility of this sequence. ⋯ Balanced steady-state free precession can facilitate ultrahigh-resolution imaging of the brain. Although total imaging times are long, the individually short phase cycles can be acquired separately, improving examination tolerability. These images may be beneficial for studies of the hippocampus, iron-containing structures such as the subthalamic nucleus and line of Gennari, and the basal cisterns and their contents.
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Investigative radiology · May 2014
Seven-tesla time-of-flight angiography using a 16-channel parallel transmit system with power-constrained 3-dimensional spoke radiofrequency pulse design.
Ultrahigh magnetic fields of 7 T or higher have proven to significantly enhance the contrast in time-of-flight (TOF) imaging, one of the most commonly used non-contrast-enhanced magnetic resonance angiography techniques. Compared with lower field strength, however, the required radiofrequency (RF) power is increased at 7 T and the contrast obtained with a conventional head transmit RF coil is typically spatially heterogeneous.In this work, we addressed the contrast heterogeneity in multislab TOF acquisitions by optimizing the excitation flip angle homogeneity while constraining the RF power using 3-dimensional tailored RF pulses ("spokes") with a 16-channel parallel transmission system and a 16-channel transceiver head coil. ⋯ Significant improvement in excitation fidelity leading to improved TOF contrast, particularly in the brain periphery, as well as smooth slab transitions can be achieved with 2-spoke excitation while maintaining the same excitation energy as that in CP mode. These results suggest that expanding parallel transmit methods, including the use of multidimensional spatially selective excitation, will also be very beneficial for other techniques, such as perfusion imaging.
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Investigative radiology · May 2014
Initial evaluation of non-contrast-enhanced magnetic resonance angiography in patients with peripheral arterial occlusive disease at 7 T.
The aim of this study was to achieve initial experience with non-contrast-enhanced (ne) magnetic resonance angiography (MRA) of the lower leg arteries in patients with peripheral arterial occlusive disease (PAOD) at 7 T. ⋯ Non-contrast-enhanced MRA by means of T1-weighted Turbo-fast low angle shot imaging at 7 T in patients with PAOD is feasible and allowed for good visualization of stenosis and occlusions in all analyzed artery segments in this small patient group. However, this study also shows the challenges of ultrahigh-field body imaging, and more experience is required to determine the impact of 7-T ne-MRA in clinical practice.
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Investigative radiology · Apr 2014
Randomized Controlled Trial Comparative StudyT1 contrast in the myocardium and blood pool: a quantitative assessment of gadopentetate dimeglumine and gadofosveset trisodium at 1.5 and 3 T.
The objective of this study was to assess the evolution of T1 contrast (T1c) between cardiovascular tissues, contrast agents, and magnetic field strengths. ⋯ Our study demonstrates the independent effects of timing, contrast agent type, and magnetic field strength on postcontrast T1c under general physiological conditions. The behaviors of T1c can be used to tailor quantitative MR imaging protocols for various clinical purposes.
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Investigative radiology · Apr 2014
Randomized Controlled Trial Comparative StudyIntraindividual comparison of diagnostic performance in patients with hepatic metastasis of full-dose standard and half-dose iterative reconstructions with dual-source abdominal computed tomography.
The objectives of the study were to evaluate the image quality and diagnostic performance of sinogram-affirmed iterative reconstruction (SAFIRE) for detecting hepatic metastasis and to estimate the potential radiation dose reduction at abdominal computed tomography (CT). ⋯ By applying SAFIRE2, the radiation dose could be reduced by up to 50% compared with the standard-of-care abdominal CT protocol without increasing image noise and without deteriorating diagnostic performance for the detection of hepatic metastasis.