摘要

目的建立双同位素标记试餐SPECT胃排空检测技术，研究健康志愿者固体、液体食物胃排空及胃内分布情况，探讨近端胃和远端胃在食物胃内分布和排空过程中的作用.

方法^99mTc-植酸钠活体标记的鸡肝为固体试餐，含糖80g/L饮料230mL中加入^113mIn-DTPA为液体试餐. 17例健康志愿者(男9例，女8例，年龄45.8岁±14.3岁)进食试餐后，平卧于带高能准直器的SPECT探头下，同步记录胃内两种同位素的活性变化，应用计算机程序划出全胃感兴趣区(ROI)、近端胃ROI和远端胃ROI，提取同位素计数，拟合出液体和固体食物胃排空曲线，获得：①固体食物排空前的迟滞相(lag time,T_L)；②固体和液体食物的近端胃半排空时间(pT₅₀)；③固体和液体食物的全胃半排空时间(T₅₀)；④远端胃内同位素最大活性(MAF)及达到MAF的时间(Tmaf).

结果试餐标记物的稳定性良好. 摄入试餐后液体成分很快开始排空，不存在T_L，排空曲线呈指数曲线，T₅₀为42min±10min，pT₅₀为39min±11min，T₅₀与pT₅₀高度正相关(P＜0.05)，与远端胃内活性变化无显著相关型(P＞0.05). 固体食物排空前有T_L(平均9min)，排空曲线为幂指数函数曲线，T₅₀为70min±16min，pT₅₀为57min±27min. 固体食物的T₅₀分别与pT₅₀，Tmaf呈正相关关系(P＜0.01)，而与MAF呈负相关(P＜0.05).

结论液体食物的胃排空曲线呈指数曲线，与近端胃的运动密切相关；固体食物的排空有赖于近端-远端胃的协调运动，它的排空曲线为双向相性的幂指数函数曲线，即先缓慢后快速排空，排空开始前存在迟滞相. 双同位素标记试餐SPECT技术是检测胃排空功能的理想手段.

中国图书馆分类号R573.2

Effect of proximal and distal stomach on the intragastric distribution and gastric emptying

WANG Cheng-Dang¹, MO Jian-Zhong² and XIAO Shu-Dong²

¹Department of Gastroenterology, The First Affiliated Hospital of Fujian Medical University, Fuzhou 350005, Fujian Province, China

²Shanghai Institute of Digestive Disease, Shanghai 200001, China

Subject headingsgastric emptying; gastrointestinal motility; isotope labeling

Abstract

AIMTo establish the technique to test gastric emptying with dual isotope labeled test meals and SPECT, and evaluate intragastric distribution and gastric emptying of solid and liquid meals in healthy volunteers.

METHODS^99mTc-PHY living labeled chicken liver served as solid food and 80g/L glucose mixed with ^113mIn-DTPA as liquid food. Seventeen healthy volunteers(9 male^113mIn- and 8 female with mean age of 45.8±14.3 yearsold) were studied.After digestion of the meals, activities of the two isotopes in different parts of gastric area(proximal and distal stomach)were read respectively with SPECT technique. The emptying curves could be derived and the emptying parameters were obtained: ① lag time(T_L)before solid emptied, ② half emptying time for solid emptied from proximal part (pT₅₀), ③ half emptying time (T₅₀)of solid or liquid emptied from the stomach, and ④ maximal activities fraction in distal stomach (MAF) and the time to reach MAF(Tmaf).

RESULTSJust after food intake, the liquid meal was quickly distributed from proximal to distal stomach and emptied with an exponential curve. T₅₀ was 42min±10min and pT₅₀39min±11min. There was a good positive relationship between them (P＜0.05). However, T_L did not exist. In contrast, solid emptying showed a power exponential curve with a lag time in the initial phase. T₅₀ was 70min±16min and pT₅₀ 57min±27min. There existed a positive relationship between T₅₀ and either pT₅₀ or Tmaf (P＜0.01，respectively), and a negative relationship between T₅₀ and MAF(P＜0.05).

CONCLUSIONLiquid emptying was related with the motility of proximal stomach, while solid was governed by the coordinated contraction of proximal and distal parts. Both the proximal and distal parts of the stomach play important roles in controlling the intragastric distribution and emptying of solid meal. The SPECT technique was good for testing emptying function.

0引言

胃运动和胃排空功能是胃的重要生理功能之一. 近年来胃动力障碍性疾病越来越受到众多学者的重视，开发了许多评价方法，其中有的需要插管或采血，另一些属非侵入性，各有优缺点，但是由于各个试验室所采用的方法和试餐不同，所获得的结果也难以直接比较. 放射性同位素胃排空试验被认为是胃排空检测的金标准^［1］. 为了准确地评估液体和固体食物的胃排空，并观察胃排空过程中食物在胃内的分布变化. 我们首次将单光子发射断层扫描(SPECT)引入胃排空功能研究的领域中，建立了双同位素标记试餐及SPECT技术检测胃排空功能的方法，并以此法研究健康志愿者的固体、液体食物胃排空及排空过程中食物的胃内分布情况，探讨近端胃和远端胃在食物胃内分布和排空过程中的作用.

1材料和方法

1.1材料健康志愿者17例，其中男9例，女8例，年龄45.8岁±14.3岁. 均无烟酒嗜好，无消化道症状，无系统性疾病及长期服药史. 试餐准备：采用Wright et al^［2］建立的鸡肝活体同位素标记技术，即：活鸡1只，显露其翼下静脉，注射^99mTc-植酸钠(PHY)111MBq，10min后杀鸡取肝，漂洗干净后蒸熟，切碎成0.5cm×0.5cm大小，称重，分成两份，与切成同样大小的方火腿混匀，可供两位受检者食用. 每份重量约150g，为固体试餐. 液体试餐为230mL含糖80g/L的饮料中加入^113mIn-DTPA37MBq混匀即成. 液体和固体试餐的总重量约350g，含蛋白质270g/kg，脂肪70g/kg，碳水化合物660g/kg. 标记物稳定性的体外试验：称取已标记的鸡肝3g，与20g切碎的方火腿混匀(1∶6.5)，加入^113mIn-DTPA标记的饮料30mL，1.0mol/L盐酸4mL，5g/L胃蛋白酶4mL混匀，置37℃水浴中并不断加压搅拌，60min和120min时将上述混合液于3500r/min离心10min，分离上清液，用滤纸吸干沉淀物上的液体，滤纸归入上清液中，分别用γ计数器采集两种成分的同位素活性各200s，按下列公式计算：

1.2方法胃排空检测的受检者隔夜禁食，次晨8h接受检测，女性应在月经期后进行，10min内摄入一份试餐，平卧于带高能准直器的SPECT探头下，摄取60s计数作为初始胃内活性(initial activity, IA),开始后的30min内每5min，尔后每15min同步记录一次胃内两种同位素的活性，每次60s，直至大部分食物离开胃内. 资料储入计算机已备调用. 选择能量峰^99mTc为139Kev，^113mIn为393Kev，窗宽(window)均为20%. 检测期间室内保持恒温恒湿，无干扰，允许受检者在室内自由活动. 应用计算机程序将胃区划分为全胃感兴趣区(ROI)、近端胃ROI和远端胃ROI. 分别从上述3个ROI中提取两种同位素的计数，进行同位素衰变校正，然后以IA为100%，将各时点的计数转换成百分数，拟合出液体和固体食物的胃排空曲线，获得以下参数：①固体食物排空开始前的迟滞相(1ag time, T_L); ②固体和液体食物近端胃半排空时间(pT₅₀)；③固体和液体食物全胃半排空时间(T₅₀)；④远端胃内两种同位素最大活性(MAF)及达到MAF的时间.

统计学处理达到MAF的时间以中位数表示，其他数据以±s表示，采用线性和非线性回归分析及相关性分析. 显著性水平设α=0.05.

2结果

体外试验表明60min及120min时^99mTc的脱落率分别为2.7%±1.1%和5.1%