ABSTRACT
Objective To investigate the application of semi-quantitative analysis of dual energy lung perfusion imaging(DEPI)in patients with acute pulmonary embolism(PE)before and after treatment.Methods 25 patients with acute PE diagnosed by dual source CT were recruited consecutively.All of them underwent CT pulmonary angiography(CTPA)and DEPI before and after treatment. Radiologists visually evaluated the PE numbers,its distribution(central or peripheral)and its nature(occlusive or non-occlusive)on CTPA.DEPI visual analysis and semi-quantitative analysis before and after treatment in different types of PE evaluated by CTPA were analyzed statistically.Results Four types of PE(central occlusive PE,central non-occlusive PE,peripheral occlusive PE and peripheral non-occlusive PE)were classified according to embolic sites and the extent of embolization.Comparing to CTPA as a standard reference,the positive rates of DEPI visual analysis were 100.00%,70.54%,87.23%,76.19% before treatment,100.00%, 76.67%,86.67%,77.78% after treatment,respectively.Significant differences were found in central occlusive PE,central non-occlusive PE and peripheral occlusive PE with mean difference of CT values before and after treatment[(70.7 ± 10.1)HU vs(29.8 ± 6.0)HU,P<0.01;(50.1 ± 9.6)HU vs(29.3 ± 7.8)HU,P< 0.01;(53.4 ± 11.4)HU vs(27.4 ± 8.9)HU,P<0.01,respectively].Although(24.5 ± 8.2)HU (after treatment)were lower than(28.5 ± 9.0)HU(before treatment),no significant difference was found in the type of peripheral non-occlusive PE(P> 0.05).Conclusion The combination of CTPA and DEPI can offer more comprehensive information of the acute PE therapeutic evaluation before and after treatment.
ABSTRACT
Objective To analyze the causes and manifestations of non-pulmonary embolism induced perfusion defects (PDs) on dual-energy perfusion imaging (DEPI) using dual source CT.Methods Consecutive 208 patients without pulmonary embolism who underwent DEPI were reviewed retrospectively.The causes of PDs were analyzed by two radiologists, the pulmonary segment numbers, the proportion and the perfusion patterns of each case were recorded and analyzed respectively.Results 1 118 of 3 716 pulmonary segments showed the PDs.Among them, 752(67.26%), 36(3.22%), 308(27.55%) and 22(1.97%) pulmonary segments had PDs due to intra-pulmonary lesions, vascular diseases, artifacts and unidentifiable causes, respectively.In PDs resulted from intra-pulmonary lesions, vascular diseases and unidentifiable causes, three patterns (wedge-shaped, heterogeneous and regionally homogeneous) were identified,and most of those PDs were heterogeneous and regionally homogeneous, which were largely in accordance with the lesions showed on non-contrast enhanced scans.Artifacts included the beam hardening artifacts and artifacts caused by heart beat or diaphragmatic movement.The PDs caused by artifacts usually had particular locations and shapes.Conclusion Understanding of the manifestations and causes of PDs in patients without pulmonary embolism can improve the diagnosis accuracy of pulmonary embolism on DEPI.