[The Optimal Start Timing of Helical Scan for Coronary CT Angiography and CT Myocardial Perfusion Scan Using 64-MDCT].

PURPOSE: Ichihara et al. (Fujita Med J 2015; 1(1): 9-14) developed a method to simultaneously obtain both coronary computed tomography (CT) angiography and CT myocardial perfusion (CTP) using 64-multi detector CT (MDCT). An input-function (time enhancement curve, TEC) of the ascending aorta (Ao) and myocardial CT density are necessary to calculate absolute myocardial blood flow (ml/g/min) using a two-compartment model. Helical scan starting timing is important to capture the peak (P) of Ao time enhancement curve (TEC). The purpose is to search the optimal timing of starting helical scan to capture the P. METHODS: We performed 14 CTPs using Definition AS+ (SIEMENS). A dynamic scan at the Ao level was started at 7 s after contrast injection and helical scan was started at various trigger on bolus tracking. Definition AS+ needs 2 s (other scanner may need 4 s) for changing from a dynamic to helical scan mode. We created TECs of pulmonary artery (PA) and Ao using the fifth function fitting. We measured the time from trigger point to the P (t200, t250, t300 and tCP). RESULTS: Mean t200, t250, t300 and tCP were 9.1±1.9, 7.9±2.0, 6.6±1.9 and 3.9±1.2 s, respectively. In additional other 16 CTP studies using the cross point method, we can capture the P in all (100%) examinations. CONCLUSION: Scan starting at the cross point is best for Definition AS+, and the Ao=300 HU may be best for other scanner that needs 4 s for changing scan mode to obtain a fine input function for calculating absolute myocardial blood flow.

Effect of benzylic oxygen on the antioxidant activity of phenolic lignans.

It has been clarified in the present investigation that a high degree of oxidation at the benzylic position of phenolic lignans bearing a 4-hydroxy-3-methoxybenzyl group reduces their antioxidant activity and that the antioxidant activity of the bis(4-hydroxy-3-methoxybenzyl)tetrahydrofuran lignan 2 is higher than that of the corresponding gamma-butyrolactone lignan 1. This was demonstrated by comparing the antioxidant activities of compounds 1 and 2 with those of the (benzyl)(hydroxybenzyl)tetrahydrofurans 3 and 4, the bis(hydroxybenzyl)tetrahydrofurans 7 and 8, the (benzoyl)(benzyl)tetrahydrofuran 6, and the dibenzoyltetrahydrofuran 9. The activity level of compound 2 was approximately the same potency as that of the tetrahydronaphthalene-tetrahydrofuran 5. These compounds possess either a 4-hydroxy-3-methoxybenzyl group or a 4-hydroxy-3-methoxybenzoyl group as the benzyl or benzoyl group. An examination of radical scavenging activity showed differences of activity between diastereomers. To make this comparison possible, compounds 1-9 were synthesized using new synthetic routes for several of these lignans. In this investigation, stereoisomers of the (benzyl)(hydroxybenzyl)tetrahydrofurans 3 and 4 and liovils 7 and 8 were synthesized for the first time.