市原 隆

Objectives: The purpose of this study was to develop a quantitative method for myocardial blood flow (MBF)measurement using contrast-enhanced multidetector computed tomography (MDCT) images with bolus tracking andhelical scanning.Materials and Methods: Nine canine models of left anterior descending artery stenosis were prepared and underwent MDCT perfusion imaging during adenosine infusion to study a wide range of flow parameters. Neutron-activated microspheres were injected to document MBF during adenosine infusion. Six animals underwent dynamic MDCT perfusion imaging, and K1 and k2 (which represent the first-order transfer constants from left ventricular blood to myocardium and from myocardium to the vascular system, respectively) were measured using a two-compartment model. The results were compared against microsphere MBF measurements, and the extraction fraction (E) of contrast agent and the mean value of k1/k2 were calculated. Six animals then underwent helical CT perfusion imaging, and neutron-activated microspheres were injected to document MBF during adenosine infusion. For each animal, based on E, K1/k2, time-registered helical CT myocardial data, and arterial input function data, tables of myocardial CT values versus MBF were simulated for various MBF values to create look-up tables from the myocardial CT value to MBF. The CT-derived MBF values were compared against the microsphere MBF measurements.Results: A strong linear correlation was observed between the MDCT-derived MBF and the microsphere MBF (y =1.065x – 0.616, R2 = 0.838).Conclusions: Regional MBF can be measured accurately using a combination of bolus tracking and time-registeredhelical CT data from contrast-enhanced MDCT scanning during adenosine stress.

負荷心筋パーフュージョンMRI画像を用いた定量解析の際、最も処理時間を必要とする左室心筋領域設定のための自動化アルゴリズムの開発を行い、得られた左室心筋の輪郭を手動にて設定した輪郭と比較し、両者の左室心筋輪郭より算出した心筋血流値を比較した。虚血性心疾患を疑い、薬剤負荷心筋パーフュージョンMRI検査を施行した17例を対象とした。5例において本法を適応することができなかった。視覚的評価では自動設定された左室心筋領域は左室および右室内腔や肺なとの心筋以外の組織を含むことなく、左室心筋領域内に設定されていた。設定した左室心筋領域の面積は手動よりも有意に大きくなった。開発した左室心筋領域の自動設定アルゴリズムは心筋パーフュージョンMRIの定量解析に要する時間を大幅に短縮し、再現性の高い定量解析を日常臨床に導入できる可能性が示唆された。