Radiation Medicine Centre, Bhabha Atomic Research Centre, Tata Memorial Centre Annexe, Jerbai Wadia Road, Parel, Mumbai, India.
Clin Nucl Med. 2010 Mar;35(3):160-4. doi: 10.1097/RLU.0b013e3181cc63a1.
During myocardial perfusion imaging with Tc-99m sestamibi, intestinal and hepatic radiotracer activity commonly interfere with visualization of the inferior wall of the myocardium leading to difficulties in interpretation. This study was undertaken to assess if carbonated lime drink ingestion prior to imaging prevents the said interference and improves the quality of images.
The study group comprised 33 consecutive patients including 26 males (age range: 30-80 years) and 7 females (42-62 years) who were referred for myocardial perfusion imaging. Of 33 patients, 21 (18 males, 3 females) were imaged at rest, 5 patients (3 males, 2 females) underwent physical stress, and 7 patients (5 males, 2 females) had pharmacological stress with adenosine. Five to 10 minutes after intravenous injection of 296 to 444 MBq (8-12 mCi) Tc-99m MIBI, anterior, and left anterior oblique (LAO) 45 degree planar views were acquired with a gamma camera using LEHR collimator. Each view was acquired for 100 seconds in a 256 x 256 matrix in all patients. Thereafter each patient was administered about 250 mL of a carbonated lime drink and repeat views were acquired within 5 minutes with the same parameters. Quantitative assessment of counts in the inferior wall of myocardium (M) to those in adjacent abdomen (A) was performed on both pre- and postintervention studies by drawing an ROI of about 50 +/- 5 pixels. M/A ratios were recorded for each patient in both the groups. The student t test was performed to evaluate the significance of difference between pre- and postintervention images. P < 0.05 was considered significant. All patients underwent myocardial perfusion single photon emission computed tomography.
It was found that the inferior wall of the myocardium was better visualized, and there was no interference from gut or hepatic tracer activity in postintervention planar and single photon emission computed tomography reconstructed views as compared with preintervention images in all patients. The M/A ratio expressed as mean +/- SD was significantly higher in the postintervention group, viz. 2.19 +/- 0.71 in the anterior and 2.07 +/- 0.70 in the LAO45 views as compared with those of preintervention values of 1.50 +/- 0.59 in the anterior and 1.41 +/- 0.49 in the LAO 45 views, respectively (P < 0.001).
We conclude that intake of carbonated lime drink is a simple and an effective technique to improve the image quality of the inferior wall of the myocardium on myocardial perfusion imaging with Tc-99m MIBI. This technique may also help in reducing the time interval between injection of radiotracer and imaging, which is otherwise delayed in routine practice.
在使用 Tc-99m sestamibi 进行心肌灌注成像时，肠道和肝脏示踪剂的放射性通常会干扰下壁心肌的可视化，导致解读困难。本研究旨在评估在成像前饮用碳酸石灰水是否可以防止这种干扰并改善图像质量。
研究组包括 33 名连续患者，其中包括 26 名男性（年龄范围：30-80 岁）和 7 名女性（42-62 岁），他们被转介进行心肌灌注成像。在 33 名患者中，21 名（18 名男性，3 名女性）在休息时进行成像，5 名（3 名男性，2 名女性）进行体力应激，7 名（5 名男性，2 名女性）接受腺苷药理学应激。在静脉注射 296 至 444MBq（8-12mCi）Tc-99m MIBI 后 5-10 分钟，使用 LEHR 准直器的伽马相机获取前位和左前斜位（LAO）45 度平面视图。在所有患者中，每个视图以 256x256 矩阵采集 100 秒。此后，每位患者饮用约 250 毫升碳酸石灰水，并在相同参数下在 5 分钟内获取重复视图。通过绘制约 50±5 像素的 ROI，在预干预和干预后研究中分别对下壁心肌（M）中的计数和相邻腹部（A）中的计数进行定量评估。记录每个患者在两组中的 M/A 比值。使用学生 t 检验评估干预前后图像之间差异的显著性。P<0.05 被认为具有统计学意义。所有患者均接受心肌灌注单光子发射计算机断层扫描。
发现与干预前图像相比，在所有患者中，干预后的平面和单光子发射计算机断层扫描重建视图中，下壁心肌的可视化更好，肠道或肝脏示踪剂活性没有干扰。干预后组的 M/A 比值表示为平均值±SD，在前位和 LAO45 视图中分别为 2.19±0.71 和 2.07±0.70，而在前位和 LAO 45 视图中分别为 1.50±0.59 和 1.41±0.49（P<0.001）。
我们得出结论，饮用碳酸石灰水是一种简单有效的技术，可以改善 Tc-99m MIBI 心肌灌注成像中下壁心肌的图像质量。该技术还可以帮助减少放射性示踪剂注射和成像之间的时间间隔，这在常规实践中会延迟。
