Purpose:To develop and test a saturation-recovery True-FISP (SR-TrueFISP) pulse sequence for first-pass myocardial perfusion imaging. Materials and Methods:First-pass magnetic resonance imaging (MRI) of Gd-DTPA (2 mL) kinetics in the heart was performed using an SR-TrueFISP pulse sequence (TR/TE/ ␣ ϭ 2.6 msec/1.4 msec/55°) with saturation preparation TD ϭ 30 msec before the TrueFISP readout. Measurements were also performed with a conventional saturation-recovery TurboFLASH (SRTF) pulse sequence for comparison.Results: SR-TrueFISP images were of excellent quality and demonstrated contrast agent wash-in more clearly than SRTF images. The signal increase in myocardium was higher in SR-TrueFISP than in SRTF data. Precontrast SNR and peak CNR were not significantly different between both sequences despite 57% improved spatial resolution for SRTrueFISP. A SUFFICIENT BLOOD SUPPLY IS essential for tissue function. Contrast enhanced myocardial perfusion imaging (MPI) with magnetic resonance imaging (MRI) has been shown to have the potential to provide insights into myocardial microcirculation qualitatively (1), semiquantitatively (2-6), and quantitatively (6 -12). ConclusionFast magnetization-prepared (e.g., saturation recovery) spoiled gradient echo pulse sequences have been used previously for MPI (2,8 -11). However, for semiquantitative (i.e., slope) and quantitative (i.e., determination of myocardial blood flow (MBF)) evaluation of first-pass MPI, a linear relation between the signal intensity and the contrast medium (CM) concentration is of advantage, because the conversion of signal intensities to CM concentrations can then be accomplished easily (6,9,10). The linearity can be achieved by using a very short delay time (TD) between the saturation pulse and the gradient echo imaging part of the sequence, and a low CM dosage. Moreover, to keep the imaging time short, very short sequence repetition times (TR) have to be used. Consequently, the MR images and the signal-time curves (STCs) derived thereof demonstrate poor signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR).With regard to SNR and CNR, conventional spoiled gradient echo pulse sequences such as the snapshotfast low-angle single-shot (TurboFLASH) (13) sequence are inefficient in that all transverse magnetization is destroyed before the next phase encoding step. In steady-state free precession pulse sequences (SSFP) (14) such as TrueFISP (15), however, the transverse magnetization is refocused after data acquisition, resulting in an addition of the refocused transverse magnetization with the newly excited transverse magnetization of the next phase encoding step. Moreover, spin echos from previous excitations are refocused. At very short TRs, TrueFISP offers higher SNRs than spoiled gradient echo pulse sequences, in particular for tissues with large T2/T1 values (T1, longitudinal relaxation time; T2, transverse relaxation time) (16). Moreover, Zur et al (16) showed that the SSFP sequence is more efficient in terms of SNR per unit time than the conve...

Left ventricular volumes assessed by the newest-generation MDCT scanners are significantly higher compared with MRI, whereas ejection fraction and cardiac output are significantly lower in MDCT. This appears to be a result of the frequent application of beta-blockers prior to MDCT examinations.

Scrotal lesions can be reliably detected, precisely localized, and characterized with MRI in everyday practice. The differential diagnosis was narrowed by use of MRI. This finding is of great clinical importance because more precise treatment strategies can be determined and surgical exploration or orchiectomy avoided by more patients.

This pilot study shows that MRI is a new noninvasive method to detect patent foramen ovale and atrial septal aneurysm. A grading is possible but warrants further investigation regarding its predictive value and impact on treatment strategies.