Objective To explore the value of right lateral decubitus position MPI for differentiating myocardial perfusion defect from cardiac anterior wall attenuation artificial defect,caused by breast of woman.Methods Forty-nine patients(average age (61.5±8.4) years) who had low likelihood of coronary artery disease and had perfusion defect in the anterior wall after exercise stress 99Tcm-MIBI MPI were included.All underwent supine and right lateral decubitus position during resting SPECT images.The myocardial perfusion SPECT images at left ventricle were reconstructed and were measured by Bull's-eye,based on the counts.Results from both supine position imaging and right lateral decubitus position imaging were compared.Paired t test was used to statistically analyse the data by SPSS 13.0.Results Compared with supine position,the counts of the anterior,inferior,apex and lateral wall in right lateral decubitus position were significantly higher:(71.30±3.53) ％ vs (66.50±3.85) ％,(70.06±4.45) ％ vs (65.44±4.16) ％,(77.90±3.00)％ vs (75.81±4.08)％,(79.30±2.26)％ vs (72.60±3.87)％ (t=6.731,5.286,3.555,10.885,all P＜0.01).The counts of septal wall were significantly lower ((66.60±3.98)％ vs (70.06±4.51)％,t=-4.625,P＜0.01) in right lateral decubitus position than that in supine position.Among the different regions of anterior wall,the counts of the anterior-middle ((76.40 ± 3.80) ％ vs (68.60 ± 4.76) ％) and anterior-apex region ((77.10±3.24) ％ vs (69.00±3.54) ％) were significantly higher (t =9.916,8.870,both P＜0.01) in right lateral decubitus position than those in supine position,but there was insignificance ((56.94±6.06)％ vs (58.50±4.98) ％,t =-1.493,P＞0.05) at anterior-basal region.The artificial defect of different degrees in anterior wall was observed in all patients in supine position,23 cases (46.9％,23/49) showed artificial defect in the anterior-middle region and 16 cases (32.7％,16/49) in the anterior-apex region.All artificial defect showed radioactive filling in right lateral position imaging,12 cases(24.5％,12/49) filled markedly and 32 cases(65.3％,32/49) filled completely.Conclusions The artificial defects caused by breast of woman mainly present in anterior-middle region and in anterior-apex region of the anterior wall in supine position imaging.The right lateral decubitus position imaging can markedly improve these artificial defects.%目的 探讨采用右侧卧位并改变采集角度显像对成年女性SPECT MPI中左心室前壁衰减伪影的鉴别价值.方法 回顾性分析行99Tcm-MIBI MPI的成年女性49例[年龄(61.5±8.4)岁,属冠心病低发人群].运动负荷显像时患者左心室前壁均出现不同程度的稀疏或缺损,随机(抽签法)对患者先后行常规仰卧位和改变采集角度的右侧卧位静息显像.重建2种显像体位的心肌断层图像,利用靶心图获得左心室各壁段的放射性计数百分比.采用配对t检验比较2种显像体位间的放射性计数百分比差异.观察不同体位显像时左心室前壁放射性稀疏和填充的图像差异.结果 左心室前壁、下后壁、心尖部及侧壁的放射性计数百分比在右侧卧位显像时明显高于仰卧位显像,分别为(71.30±3.53)％和(66.50±3.85)％,(70.06±4.45)％和(65.44±4.16)％,(77.90±3.00)％和(75.81±4.08)％,(79.30±2.26)％和(72.60±3.87)％(t=6.731、5.286、3.555和10.885,均P＜0.01),间壁的放射性计数百分比明显低于仰卧位显像[(66.60±3.98)％和(70.06±4.51)％,t=-4.625,P＜0.01].左心室前壁中段和前壁心尖部放射性计数百分比在右侧卧位显像时明显高于仰卧位显像[中段:(76.40±3.80)％和(68.60±4.76)％,心尖部:(77.10±3.24)％和(69.00±3.54)％;t=9.916和8.870,均P＜0.01],前壁基底部放射性计数百分比在2种显像体位间的差异无统计学意义[(56.94±6.06)％和(58.50±4.98)％,t=-1.493,P＞0.05].目测49例受检者常规仰卧位显像时,左心室前壁均有不同程度的稀疏或缺损,其中出现前壁中段和前壁心尖部局限性稀疏缺损的受检者分别为46.9％ (23/49)和32.7％ (16/49);采用右侧卧位同时改变采集角度显像时,左心室前壁的稀疏缺损区均有不同程度的填充,其中出现明显填充和完全填充的受检者分别为24.5％(12/49)和65.3％ (32/49).结论 仰卧位显像时成年女性左心室前壁的衰减伪影主要表现为前壁中段或前壁心尖部的局限性稀疏或缺损;采用右侧卧位同时改变采集角度显像能有效减少和鉴别成年女性左心室前壁的衰减伪影.
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