Choong Wook Lee MD, Presenter: Nothing to Disclose

Joon Beom Seo MD, PhD, Abstract Co-Author: Speaker, Siemens AG

Eun Jin Chae MD, PhD, Abstract Co-Author: Nothing to Disclose

Hyun Joo Lee, Abstract Co-Author: Nothing to Disclose

Hye Jun Hwang MD, Abstract Co-Author: Nothing to Disclose

To investigate the interval changes of pulmonary perfusion defects (PPD) in patients with acute pulmonary embolism (PE) on follow-up dual-energy CT pulmonary angiography (DECTPA).

Of 1400 patients who underwent DECTPA in suspicion of PE for past 3 years, 91 patients underwent follow-up DECTPA with various intervals (mean 6.7 months). Among them, 26 patients (M:F=10:16, mean age 62 yrs) were included with following inclusion criteria; patients 1) without pulmonary disease that might cause perfusion alteration, 2) without history of repeated PE. DECTPAs were performed with dual source CT scanner (SOMATOM Definition, Siemens). To assess the extent of PPD and vascular occlusion, each lung was regarded as having 10 segments. In each segment, PPD score was graded on 3-point scale system: 0, normal perfusion; 1, moderately reduced perfusion; 2, profoundly reduced or absent perfusion. The CT angiographic obstruction (CTAO) score was based on the Qanadli method. Each segment was classified into 4 groups according to the PPD and CTAO; normal, matched defect, mismatched PPD, mismatched CTAO. Interval changes of the segments with matched defect were assessed on follow-up DECTPA. The correlation between PPD and CTAO scores in patient level on initial and follow-up CT.

Of the total 520 segments, the number of segments with normal, matched defect, mismatched PPD and mismatched CTAO on initial CT were 212, 107, 162 and 39 segments, respectively. On follow-up CT 84.1% (90/107) of matched defect changed into normal segment with complete resolution and 1 segment showed sustained matched defect. Persistent or residual PPD without residual CTAO was seen in 10.3% (11/107) segments while residual CTAO without PPD was seen in 5 segments. Both PPD and CTAO scores decreased significantly during follow up (PPD score from 8.8 to 1.7; CTAO score from 15.3 to 0.5). Significant correlation between PPD and CTAO scores on initial CT (r = 0.70, p < 0.001) disappeared on follow-up CT (r = -0.05 p = 0.83).

Follow-up DECTPA showed resolution of PE with improvement of perfusion in most segments. However, some of mismatched residual lesions were observed which may represent the residual microcirculation disturbance or partial resolution of gross clots.

DECTPA may be useful in monitoring changes of macroscopic emboli and perfusion defects in patients with acute pulmonary embolism.

Lee, C, Seo, J, Chae, E, Lee, H, Hwang, H, The Changes in Regional Perfusion in Patients with Acute Pulmonary Embolism during Follow-up: Evaluation with Dual-Energy CT Pulmonary Angiography.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9010382.html