Purpose：Conventional pre-saturation pulse for suppressing venous signals cannot be applied to time-of-flight magnetic resonance angiography(TOF-MRA) at 7 Tesla MRI due to specific absorption rate(SAR) limitation. The SAR could be attenuated with using low saturation flip angle, but a few repetitions are needed to reach signals below the steady-state signal of the brain tissues. The purpose of this study was to suppress venous system with clinically acceptable acquisition time by using 90 degree flip angle. Methods：The standard slab-selective radio-frequency and gradient waveform were modified to new-shaped models by minimum-time variable-rate selective excitation(Min-VERSE) algorithm. Excitation slice profile was measured and evaluated by a phantom scan. In volunteer measurement, the vessel-tissue contrast ratio of the sinuses(VTCR_S) and middle cerebral artery(VTCR_MCA) were assessed in correlation to surrounding tissue and compared to the values measured by the conventional TOF(cTOF) pulse sequence. Results：The experimentally-measured profiles showed that there was good agreement between conventional and modified pulse. The total scan time was 5 min 55 sec(Min-VERSE 90 FA, TR 28 ms) and 8 min 50 sec(90 FA, TR 42 ms). The quantitative results of ROI analysis were nearly similar, except the venous signal and VTCR_S at Min-VERSE 90 FA. Conclusions：We have presented that the use of Min-VERSE with high flip angle was useful. The total acquisition time was faster about 3 minutes and the signal analysis was hardly different to the values acquired by the values of 90 FA at cTOF. Since 7T MRI has been suitable for ultra-high resolution imaging, our protocol would be used by default for diagnosing various intracranial vascular pathologies.

In the present study, we have investigated morphology and evolution of small-scale Ha dynamic features on the quiet sun by analyzing video magnetograms and high resolution Ha images simultaneously taken for 5 hours at Big Bear Solar Observatory on April 18, 1997. From comparisons between time sequential longitudinal magnetograms and Hα images covering 150" × 150", several small-scale Hα dynamic features have been observed at a site of magnetic flux cancellation. A close relationship between such features and cancelling magnetic fluxes has been revealed temporarily and spatially. Our results support that material injection by chromospheric magnetic reconnect ion may be essential in supporting numerous small-scale Hα dynamical absorption features, being in line with recent observational studies showing that material injection by chromospheric magnetic reconnect ion is essential for the formation of solar filaments.