Curtis Brian R, Cox Mougnyan, Poplawski Michael, Lyshchik Andrej
Department of Radiology, Thomas Jefferson University Hospital, 132 South 10th Street, Philadelphia, PA, 19107, USA.
Emerg Radiol. 2017 Oct;24(5):525-530. doi: 10.1007/s10140-017-1503-9. Epub 2017 Apr 12.
Ventilation and perfusion (VQ) imaging is common following suboptimal CT pulmonary angiogram (CTPA) for pulmonary embolism (PE) evaluation; however, the results of this diagnostic pathway are unclear. The purpose of our study is to determine the incidence of PE diagnosed on VQ scans performed in patients with suboptimal CTPAs.
One hundred twenty-two suboptimal CTPAs with subsequent VQ scans within 1 week were retrospectively identified. VQ reports utilizing modified prospective investigation of pulmonary embolism diagnosis (PIOPED) and prospective investigative study of acute pulmonary embolism diagnosis (PISAPED) criteria were evaluated for presence of PE; intermediate probability, high probability, and PE present were considered PE positive. Three hundred consecutive reports of each diagnostic CTPA and diagnostic VQ studies were reviewed to estimate baseline PE positive rates at our institution. These were compared to the positive VQ scan rate after suboptimal CTPA by Fisher's exact test. Reported reason for suboptimal CTPA was noted. When contrast bolus timing was suboptimal, we measured main pulmonary artery (mPA) Hounsfield units (HU). Potential alternative diagnoses in CTPA reports were noted.
97.5% (119/122) of VQ scans following suboptimal CTPA were negative for PE, and 2.5% (3/122) were positive for PE. This was significantly lower than baseline PE positive rate of 10.7% (32/300, p < 0.01) for VQ imaging, and 10.3% (31/300, p < 0.01) for CTPA at our institution. Most (79.5%) CTPAs were suboptimal due to contrast timing. Average mPA density in these cases was 164 ± 61 HU. Most of these studies ruled out central PE. Potential alternative diagnosis was reported in 34/122 (28%) of suboptimal CTPAs, for which pneumonia accounted 59%.
There is very low incidence of PE diagnosed on VQ imaging performed after suboptimal CTPA. This may be attributed to the ability of most suboptimal CTPAs to rule out central PE.
对于肺栓塞（PE）评估，在CT肺动脉造影（CTPA）效果欠佳后进行通气灌注（VQ）成像是常用方法；然而，这一诊断途径的结果尚不清楚。我们研究的目的是确定在CTPA效果欠佳的患者中进行VQ扫描时诊断出PE的发生率。
回顾性确定122例CTPA效果欠佳且在1周内随后进行VQ扫描的病例。根据改良的肺栓塞诊断前瞻性研究（PIOPED）和急性肺栓塞诊断前瞻性研究（PISAPED）标准对VQ报告进行评估，以确定是否存在PE；中度可能性、高度可能性以及存在PE均被视为PE阳性。对300份连续的诊断性CTPA和诊断性VQ研究报告进行审查，以估计我们机构的基线PE阳性率。通过Fisher精确检验将这些结果与CTPA效果欠佳后的VQ扫描阳性率进行比较。记录CTPA效果欠佳的报告原因。当对比剂团注时间欠佳时，我们测量主肺动脉（mPA）的Hounsfield单位（HU）。记录CTPA报告中潜在的其他诊断。
CTPA效果欠佳后进行的VQ扫描中，97.5%（119/122）的结果为PE阴性，2.5%（3/122）为PE阳性。这显著低于我们机构VQ成像的基线PE阳性率10.7%（32/300，p<0.01）以及CTPA的基线PE阳性率10.3%（31/300，p<0.01）。大多数（79.5%）CTPA效果欠佳是由于对比剂注射时间。这些病例中mPA的平均密度为1,64±61HU。这些研究大多排除了中心型PE。在122例CTPA效果欠佳的病例中，有34例（28%）报告了潜在的其他诊断，其中肺炎占59%。
CTPA效果欠佳后进行VQ成像时诊断出PE的发生率非常低。这可能归因于大多数CTPA效果欠佳的病例能够排除中心型PE。
