Gosselin Marc V, Rassner Ulrich A, Thieszen Sheldon L, Phillips Jinnah, Oki Allison
Department of Radiology, Oregon Health and Science University, Portland, OR 97201, USA.
J Thorac Imaging. 2004 Jan;19(1):1-7. doi: 10.1097/00005382-200401000-00001.
Several artifacts have been observed during contrast-enhanced CT of the pulmonary arteries. We describe a physiological artifact caused by a transient interruption of the contrast column in the pulmonary arteries associated with inspiration immediately prior to imaging. This results from a variable inflow of unopacified blood from the inferior vena cava (IVC).
From 327 consecutive pulmonary CT-angiograms, all performed on a single detector scanner at 3 mm collimation (1.5 mm incremental reconstruction), 50 positive studies, 46 indeterminate studies, and 33 negative studies (129 exams) were retrospectively reviewed by a blinded observer to determine the frequency of the described contrast interruption, its severity (mild, moderate, or severe), and its possible contribution to misinterpretation of studies. The numerical change in Hounsfield units was assigned within the right ventricular chamber for each examination to correlate with the subjective evaluation of severity. Statistical significance was determined with P = 0.05%.
The artifact was present in 48 (37.2%) of the 129 evaluated studies. It was greater in frequency (50.0%) with the negative studies. The presence was 25% with positive studies and 36.7% with indeterminate exams. The interruption was more often mild (<100 HU change) in severity (45.8%). Three (6.6%) definite false positives were detected where the misinterpretation was directly attributed to the artifact. Three (6.6%) other examinations called positive were also directly related to the interrupted contrast column. However, since no further pulmonary vascular evaluation was performed, these examinations can only be considered indeterminate. Two of the latter 3 studies demonstrated a severe (>150 HU change) and the other study demonstrated a moderate (100-150 HU) interruption of contrast opacification.
During inspiration, there is a variable increase in unopacified venous blood from the IVC, briefly diluting the contrast column entering from the SVC. This interruption is common, though usually mild in severity. However, a short severe interruption of vascular opacification can lead to misinterpretation as a pulmonary embolus or contribute to an indeterminate examination.
在肺动脉对比增强CT检查过程中观察到了几种伪影。我们描述了一种生理伪影，它是由成像前即刻吸气相关的肺动脉内造影剂柱短暂中断引起的。这是由于来自下腔静脉（IVC）的未造影血液的可变流入所致。
在一台单探测器扫描仪上以3mm准直（1.5mm增量重建）进行的327例连续肺部CT血管造影中，由一名盲法观察者对50例阳性研究、46例不确定研究和33例阴性研究（共129次检查）进行回顾性分析，以确定所描述的造影剂中断的频率、严重程度（轻度、中度或重度）及其对研究误判的可能影响。对每次检查在右心室内的亨氏单位数值变化进行赋值，以与严重程度的主观评估相关联。以P = 0.05%确定统计学显著性。
在129例评估研究中，48例（37.2%）出现了这种伪影。在阴性研究中其频率更高（50.0%）。在阳性研究中出现率为25%，在不确定检查中为36.7%。中断严重程度多为轻度（亨氏单位变化<100）（45.8%）。检测到3例（6.6%）明确的假阳性，其误判直接归因于伪影。另外3例（6.6%）被判定为阳性的检查也与造影剂柱中断直接相关。然而，由于未进行进一步的肺血管评估，这些检查只能被视为不确定。后3项研究中的2项显示为严重（亨氏单位变化>150）中断，另一项研究显示为中度（100 - 150亨氏单位）造影剂充盈中断。
吸气时，来自下腔静脉的未造影静脉血可变增加，短暂稀释了从 Superior Vena Cava（SVC）进入的造影剂柱。这种中断很常见，尽管严重程度通常较轻。然而，血管造影剂充盈的短暂严重中断可导致误诊为肺栓塞或导致检查结果不确定。 （注：原文中Superior Vena Cava首字母大写，这里翻译为上腔静脉，推测可能是原文输入有误，正常应该是小写形式superior vena cava ）
