Coordenação de Ensino E Pesquisa, Instituto Nacional de Cardiologia, Rua das Laranjeiras 374, Rio de Janeiro, RJ, Brazil.
Laboratório de Biologia Celular E Tecidual, Centro de Biociências E Biotecnologia, Universidade Estadual Do Norte Fluminense Darcy Ribeiro, Rio de Janeiro, RJ, Brazil.
BMC Cardiovasc Disord. 2022 Sep 3;22(1):394. doi: 10.1186/s12872-022-02839-8.
As patient exposure to ionizing radiation raises concern about malignancy risks, this study evaluated the effect of ionizing radiation on patients undergoing myocardial perfusion imaging (MPI) using the comet assay, a method for detection of DNA damage.
Patients without cancer, acute or autoimmune diseases, recent surgery or trauma, were studied. Gated single-photon myocardial perfusion imaging was performed with Tc-99m sestamibi. Peripheral blood was collected before radiotracer injection at rest and 60-90 min after injection. Single-cell gel electrophoresis (comet assay) was performed with blood lymphocytes to detect strand breaks, which determine a "comet tail" of variable size, visually scored by 3 observers in a fluorescence microscope after staining (0: no damage, no tail; 1: small damage; 2: large damage; 3: full damage). A damage index was calculated as a weighted average of the cell scores.
Among the 29 individuals included in the analysis, age was 65.3 ± 9.9 years and 18 (62.1%) were male. The injected radiotracer dose was 880.6 ± 229.4 MBq. Most cells (approximately 70%) remained without DNA fragmentation (class 0) after tracer injection. There were nonsignificant increases of classes 1 and 2 of damage. Class 3 was the least frequent both before and after radiotracer injection, but displayed a significant, 44% increase after injection.
While lymphocytes mostly remained in class 0, an increase in class 3 DNA damage was detected. This may suggest that, despite a probable lack of biologically relevant DNA damage, there is still a need for tracer dose reductions in MPI.
由于患者接触电离辐射会引起恶性肿瘤风险的担忧，本研究采用彗星试验（一种检测 DNA 损伤的方法）评估了电离辐射对接受心肌灌注成像（MPI）的患者的影响。
研究对象为无癌症、急性或自身免疫性疾病、近期手术或外伤的患者。采用 Tc-99m sestamibi 进行门控单光子 MPI。在放射性示踪剂注射前休息时和注射后 60-90 分钟采集外周血。使用血液淋巴细胞进行单细胞凝胶电泳（彗星试验）以检测链断裂，这决定了大小可变的“彗星尾巴”，经染色后 3 位观察者在荧光显微镜下进行视觉评分（0：无损伤，无尾巴；1：小损伤；2：大损伤；3：完全损伤）。通过细胞评分的加权平均值计算损伤指数。
在分析的 29 名个体中，年龄为 65.3±9.9 岁，18 名（62.1%）为男性。注射的放射性示踪剂剂量为 880.6±229.4MBq。大多数细胞（约 70%）在示踪剂注射后仍未发生 DNA 断裂（0 级）。损伤 1 级和 2 级的增加没有统计学意义。0 级和 1 级的细胞比例最高，分别为 69.7%和 24.3%；3 级的细胞比例最低，为 6.0%。注射后，3 级细胞的比例显著增加了 44%。
虽然大多数淋巴细胞仍处于 0 级，但检测到 3 级 DNA 损伤增加。这可能表明，尽管可能缺乏生物学相关的 DNA 损伤，但 MPI 仍需要减少示踪剂剂量。
