Factors affecting the lung perfused blood volume in patients with intrapulmonary clots after anti-coagulation therapy.

Objectives Factors affecting the improvement in the lung perfused blood volume (LPBV) were evaluated based on the presence of intrapulmonary clots (IPCs) after anti-coagulation therapy using 64-slice dual-energy CT. Materials and methods 96 patients exhibiting venous thromboembolism underwent initial and repeated LPBV examinations between December 2008 and July 2014. Fifteen patients were excluded due to pulmonary comorbidities, and a total of 81 patients were included in this study. Acute pulmonary embolism (PE) was diagnosed in 46 of the patients (56.7%). LPBV images were three-dimensionally reconstructed with two threshold ranges: 1–120 HU (V 120 ) and 1–5 HU (V 5 ), and the relative value of V 5 per V 120 expressed as %V 5 . These values were subsequently compared with indicators of the severity of PE, such as the D-dimer level, heart rate and CT measurements. This study was approved by the local ethics committee. Results In patients with IPCs, the D-dimer, V 5 and %V 5 values were significantly larger ( p ≤ 0.01) in the initial LPBV, although these differences disappeared in subsequent LPBV after treatment. The right ventricular (RV) diameter, RV/left ventricular (RV/LV) diameter ratio and %V 5 values were also significantly reduced, whereas the V 5 value did not significantly decrease ( p = 0.07), but V 120 value significantly increased ( p < 0.001) after treatment. However, in patients with IPCs the change rate in %V 5 [(subsequent-initial)/initial %V 5 ] showed a better correlation with that in V 5 ( r = 0.94, p < 0.001) rate than that in V 120 ( r = 0.19, p = 0.19) after treatment. Conclusions Increased whole lung perfusion (V 120 ) and a decreased low perfusion volume (V 5 ) affect the improvement in the %V 5 values after treatment. [ABSTRACT FROM AUTHOR]