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Purpose To evaluate and to compare Parallel Imaging and Compressed Sensing acquisition and reconstruction frameworks based on simultaneous multislice excitation for high resolution contrast-enhanced myocardial first-pass perfusion imaging with extended anatomic coverage. Materials and Methods The simultaneous multislice imaging technique MS-CAIPIRINHA facilitates imaging with significantly extended anatomic coverage. For additional resolution improvement, equidistant or random undersampling schemes, associated with corresponding reconstruction frameworks, namely Parallel Imaging and Compressed Sensing can be used. By means of simulations and in vivo measurements, the two approaches were compared in terms of reconstruction accuracy. Comprehensive quality metrics were used, identifying statistical and systematic reconstruction errors. Results The quality measures applied allow for an objective comparison of the frameworks. Both approaches provide good reconstruction accuracy. While low to moderate noise enhancement is observed for the Parallel Imaging approach, the Compressed Sensing framework is subject to systematic errors and reconstruction induced spatiotemporal blurring. Conclusion Both techniques allow for perfusion measurements with a resolution of 2.0 × 2.0 mm and coverage of six slices every heartbeat. Being not affected by systematic deviations, the Parallel Imaging approach is considered to be superior for clinical studies.

Purpose To optimize the spatial response function (SRF) while maintaining optimal signal to noise ratio (SNR) in T weighted turbo spin echo (TSE) imaging by prospective density weighting. Materials and Methods Density weighting optimizes the SRF by sampling the k-space with variable density without the need of retrospective filtering, which would typically result in nonoptimal SNR. For TSE, the T decay needs to be considered when calculating an optimized sampling pattern. Simulations were carried out and T weighted in vivo TSE measurements were performed on a 3 Tesla MRI system. To evaluate the SNR, reversed centric density weighted and retrospectively filtered Cartesian acquisitions with identical measurement parameters and SRFs were compared with TE = 90 ms and a density weighted k-space sampling optimized to yield a Kaiser function for SRF side lobe suppression for white matter. Results Density weighting of a reversed centric reordering scheme resulted in an SNR increase of (43 ± 13)% compared with the Cartesian acquisition with retrospective filtering while maintaining comparable contrast behavior. Conclusion Density weighting is applicable to TSE imaging and results in significantly increased SNR. The gain can be used to shorten the measurement time, which suggests applying density weighting in both time and SNR constrained MRI.

Purpose To determine whether the recently applied technique of acquisition-weighted 31P-MR spectroscopy (AW-MRS) allows for the detection of depressed energy metabolism in patients with inferior wall myocardial infarctions. Materials and Methods Eight patients with subacute myocardial infarction and wall motion abnormalities restricted to the inferior wall were examined with a 1.5-T MR scanner. Global and regional left ventricular (LV) function was assessed by cine MRI, and the size and extent of myocardial infarction was assessed by late enhancement (LE). MRS was performed with an AW three-dimensional chemical shift imaging sequence. Phosphocreatine/ATP ratios were determined with the postprocessing model AMARES for four voxels positioned in the anterior, lateral, inferior, and septal parts of the LV. Results The LV ejection fraction (EF) was reduced to 37.5% ± 9.0%. Seven of eight patients had transmural LE in the inferior wall, and one patient showed subendocardial enhancement in the inferior-lateral parts. Phosphocreatine/ATP ratios of the inferior wall were significantly reduced (P < 0.05) compared to all other parts of the LV (1.03 ± 0.39 (inferior), 1.67 ± 0.81 (lateral), 1.73 ± 0.29 (anterior), and 1.49 ± 0.31 (septal)). The ratios in five of seven patients with transmural enhancement were

Purpose To show the application of auto-sensitivity encoding (SENSE)—a self-calibrating parallel imaging technique—to first pass perfusion imaging of the whole human heart. Materials and Methods The self-calibrating parallel imaging method auto-SENSE was implemented for a saturation recovery turbo-fast low-angle shot (FLASH) sequence on a 1.5-T scanner using a standard four-element body phased array coil. By reducing the acquisition time per slice by a factor of two compared to conventional turbo FLASH imaging, the number of imaged slices could be doubled to six to ten with an unchanged temporal resolution of one image per heartbeat. This technique has been tested in eight healthy volunteers for contrast-enhanced heart perfusion imaging. Results Auto-SENSE heart perfusion imaging with improved coverage of the human heart could be performed successfully in all volunteers. A first quantitative comparison of perfusion values between the auto-SENSE and the non-SENSE techniques shows good agreement. Conclusion Auto-SENSE allows perfusion imaging of the whole human heart without gaps. J. Magn. Reson. Imaging 2003;18:702–708. © 2003 Wiley-Liss, Inc.

Purpose: To evaluate the feasibility and reproducibility of a noninvasive, rapid and quantitative pulmonary perfusion mapping method using a two-compartment tissue model in combination with a 1H spin labeling technique. Materials and Methods: Ten healthy volunteers and three patients with cystic fibrosis (CF) were examined on a 1.5-T whole-body scanner. Global and selective lung T1 maps based on an inversion recovery Snapshot FLASH technique were acquired from each subject with breath-holds at end-expiration. For comparison, corresponding Gd-DTPA-enhanced 1H MR perfusion images were also obtained from each CF patient. Results: Quantitative perfusion maps were calculated from the global and selective T1 maps. The measured perfusion rates of the upper right lung in volunteers ranged from 400 to 600 mL/100 g/minute. The method showed a high intra-study reproducibility and low relative errors. In CF-patients, perfusion defects detected using Gd-DTPA-enhanced MR imaging were also detected using the spin labeling method. The perfusion rates of diseased lung tissues were less than 200 mL/100 g/minute. Conclusion: Noninvasive, robust and quantitative 1H MR mapping of pulmonary perfusion was successfully performed using a rapid lung T1 mapping in combination with spin labeling within the imaging slice. The proposed method has the potential to provide both important qualitative functional information and quantitative pulmonary perfusion rates in various lung diseases at various stages without the need of contrast agents. J. Magn. Reson. Imaging 2003;18:260–265. © 2003 Wiley-Liss, Inc.

Phosphorus magnetic resonance spectroscopy (31P-MRS) has revealed a lot about the biochemistry of physiological and pathological processes in the heart. Nevertheless, until today, cardiac 31P-MRS has not had any clinical impact, albeit some pioneering studies demonstrated that 31P-MRS can indeed provide diagnostic information. In this paper, the development of techniques for human cardiac 31P-MRS over the past decade is reviewed, and the requirements for a reliable clinical measurement protocol are discussed. Spatial localization with optimal pointspread function (SLOOP) is a new method to achieve spatial localization and absolute quantitation. Its properties are detailed, and preliminary findings in patients with dilated cardiomyopathy or myocardial infarction are presented.

We demonstrate the feasibility of a new versatile hybrid imaging concept, the combined acquisition technique (CAT), for cardiac imaging. The cardiac CAT approach, which combines new methodology with existing technology, essentially integrates fast low-angle shot (FLASH) and echoplanar imaging (EPI) modules in a sequential fashion, whereby each acquisition module is employed with independently optimized imaging parameters. One important CAT sequence optimization feature is the ability to use different bandwidths for different acquisition modules. Twelve healthy subjects were imaged using three cardiac CAT acquisition strategies: a) CAT was used to reduce breath-hold duration times while maintaining constant spatial resolution; b) CAT was used to increase spatial resolution in a given breath-hold time; and c) single-heart beat CAT imaging was performed. The results obtained demonstrate the feasibility of cardiac imaging using the CAT approach and the potential of this technique to accelerate the imaging process with almost conserved image quality.

We describe a case of progressive deep venous thrombosis and chest pain studied by contrast-enhanced magnetic resonance (MR) angiography with the new intravascular contrast medium CLARISCAN (NC100150 Injection). Combined MR venography and angiography demonstrated pelvic vein thrombosis and consecutive pulmonary embolism caused by a large abdominal tumor, diagnosed as an ovarian cancer after surgery. The potential role of an intravascular contrast medium for studying the vascular system in multiple regions of the body within a single examination without the need for bolus timing is discussed. J. Magn. Reson. Imaging 2000;12:497-500.