Bulk liquid water is a strong absorber in the terahertz (THz) frequency range, due to which liquid water has historically been sworn off as a source for THz radiation. Here, we experimentally demonstrate the generation of broadband THz waves from liquid water excited by femtosecond laser pulses. Our measurements reveal the critical dependence of the THz field upon the relative position between the water film and the focal point of the laser beam. The THz radiation from liquid water shows distinct characteristics when compared with the THz radiation from air plasmas with single color optical excitation. First, the THz field is maximized with the laser beam of longer pulse durations. In addition, the p-polarized component of the emitted THz waves will be influenced by the polarization of the optical excitation beam. It is also shown that the energy of the THz radiation is linearly dependent on the excitation pulse energy.

3.0-T magnetic resonance (MR) angiography and MR imaging were compared with conventional angiography for the evaluation of moyamoya disease in 13 preoperative patients (26 hemispheres) with moyamoya disease (4 males and 9 females aged 21-54 years). The correlation between MR angiography scores determined by modified Houkin's grading system (MRA score) and conventional angiography stages determined by Suzuki's grading system (CA stage) was analyzed. Other MR findings such as moyamoya vessel scores,``ivy sign'' scores, and the presence of small, medium, and large cerebrovascular attack (CVA) lesions were compared with CA stages. MRA scores were significantly correlated with CA stages (p º 0.01). Moyamoya vessel scores correlated well with CA stages (p º 0.01). There was no significant correlation between``ivy sign'' scores and CA stages, and no significant differences in CA stages with the presence and absence of CVA lesions of any size. 3.0-T MR angiography can be used as a vascular assessment in moyamoya disease with its priority of noninvasive nature and visual clarity compared with conventional angiography. The findings of 3.0-T MR angiography may reflect the stenoocclusive changes in moyamoya disease.