Institute of Clinical Radiology and Nuclear Medicine, University Medical Centre Mannheim, Medical Faculty Mannheim-Heidelberg University, Mannheim, Germany.
Institute of Radiology and Nuclear Medicine, Clinical Research Unit, Hirslanden Hospital St. Anna, Luzern, Switzerland.
PLoS One. 2019 Jan 17;14(1):e0210473. doi: 10.1371/journal.pone.0210473. eCollection 2019.
To assess the occurrence of transient interruption of contrast (TIC) phenomenon in pulmonary computed tomography angiography (CTPA) exams performed in inspiratory breath-hold after patients were told to inspire gently.
In this retrospective single-centre study, CTPA exams of 225 consecutive patients scanned on a 16-slice CT scanner system were analysed. A-priori to measurements, exams were screened for inadequate pulmonary artery contrast due to incorrect bolus tracking or failure of i.v. contrast administration. Those exams were excluded. Attenuation values in the thoracic aorta and in the pulmonary trunk were assessed in duplicate measurements (M1 and M2) and the aorto-pulmonary density ratio was calculated. An aorto-pulmonary ratio > 1 with still contrast inflow being visible within the superior vena cava was defined as TIC.
3 patients were excluded due to incorrect bolus tracking. Final analysis was performed in 222 patients (mean age 65 ± 19 years, range 18 to 99 years). Mean density in the pulmonary trunk was 275±17 HU, in the aorta 208 ± 15 HU. Mean aorto-pulmonary ratio was 0.81± 0.29. 48 patients (21.6%) had an aorto-pulmonary ratio >1. Correlation of mean aorto-pulmonary ratio and age was: -0.213 (p = 0.001). Age was not significantly different for an aorto-pulmonary ratio >1 vs. ≤1 (p = 0.122). Both in M1 and M2, 33/222 patients presented with absolute HU values of < 200 HU within the pulmonary artery. In M1 measurements, 24 of these 33 patients (72%) fulfilled TIC criteria (M2: 25/33 patients (75%)).
TIC is a common phenomenon in CTPA studies with inspiratory breath-hold commands after patients were told to inspire gently with an incidence of 22% in our retrospective cohort. Occurrence of TIC shows a significant negative correlation with increasing age and disproportionately often occurs in patients with lower absolute contrast density values within their pulmonary arteries.
评估在告知患者轻柔吸气后进行吸气屏气的肺部 CT 血管造影（CTPA）检查中，出现短暂性对比中断（TIC）现象的发生率。
在这项回顾性单中心研究中，分析了 225 例连续患者在 16 层 CT 扫描仪系统上进行的 CTPA 检查。在进行测量之前，检查了由于不正确的团注追踪或静脉内造影剂给药失败而导致肺动脉对比不足的情况。排除了这些检查。在两次测量（M1 和 M2）中评估了胸主动脉和肺动脉主干中的衰减值，并计算了主动脉-肺动脉密度比。定义当仍然可见对比剂流入上腔静脉内时，主动脉-肺动脉比值＞1 为 TIC。
由于不正确的团注追踪，有 3 例患者被排除。最终对 222 例患者（平均年龄 65±19 岁，范围 18 至 99 岁）进行了分析。肺动脉主干的平均密度为 275±17HU，主动脉为 208±15HU。平均主动脉-肺动脉比值为 0.81±0.29。48 例（21.6％）的患者主动脉-肺动脉比值＞1。平均主动脉-肺动脉比值与年龄的相关性为：-0.213（p=0.001）。主动脉-肺动脉比值＞1 与≤1 的患者年龄无显著差异（p=0.122）。在 M1 和 M2 中，222 例患者中有 33 例肺动脉内绝对 HU 值＜200HU。在 M1 测量中，这 33 例患者中的 24 例（72％）符合 TIC 标准（M2：33 例患者中的 25 例（75％））。
在告知患者轻柔吸气后进行吸气屏气的 CTPA 研究中，TIC 是一种常见现象，在我们的回顾性队列中发生率为 22％。TIC 的发生与年龄呈显著负相关，并且不成比例地发生在肺动脉内绝对对比密度值较低的患者中。
