CT三维容积测量技术在评估房间隔缺损大小中的应用研究

Assessment of atrial septal defect size with three-dimensional volumetric measurement of cardiac CT： comparison with size of the postoperative occluder

目的比较两种实用CT三维容积测量技术评估房间隔缺损大小的可行性及准确性。方法回顾性分析50例成功施行房间隔缺损封堵术的患者资料，患者均于术前行冠状动脉CTA检查以除外冠心病，并于术后第2天拍摄正、侧位X线胸片。将患者冠状动脉CTA资料进行三维容积重组，分别用CT横断序列辅助测量技术（CTAS）及CT内镜辅助测量技术（CTVE）测量房间隔缺损的长径与短径，并利用椭圆的等效圆转换公式D=√b4/a2＋a2-b2推算等效圆直径D值，作为两种测量方法所得CT三维容积测量值；在侧位X线胸片上测量封堵术后封堵器的腰部直径（POS），以此作为房间隔缺损直径测量的参照标准。用t检验分析两种CT三维容积测量方法测得的ASD直径测量值，用Pearson检验分析二者与金标准之间的相关性以及与术中使用封堵器大小之间的相关性。结果CTAS测量值与CTVE测量值长径之差为-9．05mm（t=-6．60，P〈0．05），短径之差为-4．86mm（t=-4．39，P〈0．05），等效圆直径之差为-7．65him（t=-6．40，P〈0．05）。CTAS测量值[（22．48±5．59）mm]与POS测量值[（27．07±6．83）mm]之间呈正相关（r=0．94，P〈0．01），其线性回归方程为Y=1．14X＋1．39（R2=0．87，P〈0．05），CTAS测量值与封堵器（ASO）型号之间呈正相关（r=0．88，P〈0．01），其线性回归方程为Y=1．02X＋6．84（R2=0．78，P〈0．05）；CTVE测量值f（30．13±9．27）mm]与POS测量值之间相关性差（r=0．41，P〈0．01），其线性回归方程为Y=0．30X＋17．94（R。=0．17，P〈0．05）。结论CTAS可准确测量房间隔缺损大小，CTVE可直观评估房间隔缺损的位置与形态，二者结合，可全面评估房间隔缺损并指导封堵器的选择。

Objective To evaluate two kinds of practical CT three-dimensional volumetric measurement techniques in assessing atrial septal defects （ASDs） for transcatheter device closure. Methods Retrospective assessment of 50 consecutive patients who underwent ASD closure was conducted. Cardiac CT was performed in them before planned transcatheter ASD closure and postoperative chest radiograph was performed in both posteroanterior and lateral view. Coronary CT angiography was made for the detection of coronary artery disease, and three-dimensional reconstruction of ASD was conducted for determination of the defect size in the GE-workstation. Two kinds of practical CT three-dimensional volumetric measurement techniques, one named CT virtual endoscopy assisted volumetric measurement （ CTVE ） and another called axial sequence assisted volumetric measurement（ CTAS ）, were used to calculate the major axis and the nfinor axis of the ASD respectively. Thus, the dimensions of the Equivalent Circle were derived, with circumference and area equal to the elliptic ASD according to the formulation （D = √b4/a2 ＋ a2 -b2）. The ASDs occluder （ASO） dimension was measured in the lateral chest radiograph, and this postoperative occluder-waist size （POS） value was regarded as the gold standard for the measurement of ASD. The results were compared between CTVE and CTAS, and the correlations were evaluated between them and the gold standard. Results The differences in the major dimensions （ - 9. 05 mm, t = - 6. 60, P 〈 0.05） , minor dimensions （ - 4. 86 mm, t = - 4. 39,P 〈 0. 05 ） and Equivalent circle dimensions （ - 7.65 mm, t = - 6. 40, P 〈 0. 05 ） of ASD between CTAS and CTVE were statistically significant. Though the CTAS cannot provide the en face views of ASDs ,the Equivalent Circle dimensions measured by CTAS（22.48 ＋ 5.59） mm was correlated well with POS （27. 07± 6. 83 ） mm （ Y = 1.14X ＋ 1.39, r = 0. 94, P 〈 0. 01 ）, and a good correlation was found between this Equivalent Circle dimensions and ASO size （Y = 1.02X ＋6. 84, R2 =0.78,r =0. 88,P 〈0. 05）. The correlation between the Equivalent Circle dimensions measured by using CTVE （30. 13 ± 9.27 ） mm and POS was poor （Y =0. 30X ＋ 17.94, r = 0. 41 ,P 〈 0. 01 ） ,though it can provide the en face views of ASDs. Conclusion CTVE and CTAS are two complementary techniques of assessing ASDs for transcatheter device ClOSUre.