The aims of this study were to elucidate signal pattern of cerebral aneurysm clip in brain magnetic resonance angiography (MRA) using non-contrast enhanced ultra-short echo time (UTE) sequence and to explore effective utilization of this novel technique for patients, who underwent cerebral aneurysm clipping. The clip was embedded in homemade phantom and scanned using UTE sequence. We investigated characteristic features of the artifacts derived from the clip. Besides, we compared the volume of signal loss between conventional time-of-flight (TOF) and UTE-MRA in 50 patients with the cerebral aneurysm clip. In phantom study, the clip was delineated as signal void area fully surrounded by high signal on original images. On reconstructed short-axial views for the clip, fourleaf clover pattern of artifact was observed when clip was arranged orthogonal to the static magnetic field. On the other hand, this artifact disappeared when the clip was arranged in parallel with the static magnetic field. The volume of signal loss in clinical cases was significantly reduced in UTE-MRA (P < 0.05): 1.30, 0.52-2.77 cm 3 for TOF; 0.84, 0.28-1.74 cm 3 for UTE (median, range). The scan time for UTE-MRA was 2 minutes and 52 seconds. To understand the characteristic feature of the artifacts from the clip could contribute to define vascular structure in image interpretation. Adding UTE-MRA to routine protocol is useful approach for follow-up imaging after cerebral aneurysm clipping with clinically acceptable prolongation of the scan time.

In stereotactic radiosurgery for intracranial lesions, optimization of the dose to the at-risk organs is important to avoid neurological complications. We aimed to quantify the dose to the pyramidal tract (PT) and improve treatment planning for gamma knife radiosurgery by combining tractography. Pyramidal tractography images were depicted in 23 patients with lesions adjacent to the PT and fused with stereotactic magnetic resonance images. We regarded the PT as an at-risk organ and performed dose planning. To assess the efficacy of this process, we compared clinical parameters between plans with and without tractography. In the plans with tractography, the maximum PT dose was significantly reduced, although the irradiation time was prolonged by 3.5 min. There was no significant difference in the dose covering 95% of the lesion volume (D95). This result suggests that the PT dose can be reduced while maintaining the D95 with clinically acceptable prolongation of the irradiation time.

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Purpose: Coronary plaque progression despite very low levels of LDL-C has been reported in the patients with coronary artery disease (CAD) who received intensive statin therapy (IST). Coronary CT Angiography (CCTA) has been applied to evaluate vulnerable coronary plaques having low attenuation of CT value. The major function of PCSK9 is the binding to hepatic LDL receptors, leading to their degradation. PCSK9 is produced also in vascular smooth muscle cells constituting the atherosclerotic lesion in addition to hepatocytes. PCSK9 promotes foam cell formation by suppressing the excretion of cholesterol from macrophages. Statin is demonstrated to promote PCSK9 production. PCSK9 has been proposed to play a crucial role in the pathogenesis of IST resistance. The present study was performed to establish a novel therapeutic approach to IST resistant vulnerable plaque of coronary artery in diabetic patients. Methods: The present study included 142 T2DM patients with non-FHC asymptomatic CAD who developed vulnerable coronary plaques despite IST over 2 years. CCTA by use of 320-slice CT was applied to evaluate vulnerable coronary plaques. During the administration of anti-PCSK9 antibody, changes in serum lipids and CT value of vulnerable coronary plaques were determined. Results: During 1 year administration of anti-PCSK9 antibody, 74% decrease in serum LDL-C was observed. Also, improvement of vulnerable coronary plaque, e.g., rise in the CT value of plaque (from 43.2 ±12.0 HU to 128.5 ± 52.3 HU, p&lt;0.0001) was observed. Of the 142 patients, 95 patients finished the administration of the drug. Conclusion: One year administration of anti-PCSK9 antibody produced a significant stabilization of vulnerable coronary plaques in the patients with asymptomatic CAD who are resistant to IST. An analysis of the plaque quality by CCTA is useful method for the evaluation of the effect of the drug on vulnerable coronary plaques. Disclosure A. Hirai: None. K. Fujimura: None. K. Hirai: None. S. Kondo: None. A. Shirakami: None. T. Sakai: None. K. Murata: None. H. Taniai: None. K. Okuzaki: None. T. Kageyama: None.

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