Novel imaging approach using dual-layer CT to assess anticoagulant therapy efficacy in acute pulmonary embolism

BackgroundTo study the effects of direct oral anticoagulant (DOAC) treatment in patients with acute pulmonary embolism (PE), it is important to analyze iodine density perfusion maps by dual-layer spectral detector computed tomography (DLCT).PurposeTo investigate whether the total lung iodine value (TLIV) obtained from CT pulmonary angiography (CTPA) using DLCT provides valuable insights for assessing treatment response in acute PE.Material and MethodsWe conducted a retrospective study enrolling individuals receiving DOAC therapy for acute PE. Using DLCT, lung CT imaging before contrast was performed, followed by two contrast phases (when the region of interest in the pulmonary artery exceeded 150 HU [pulmonary arterial phase (PAP)] and 60 s after the start of contrast administration). Changes in TLIV and TLIV/LV were assessed from pre-treatment to post-DOAC treatment in both greater clot resolution group (group 1) and lesser clot resolution group (group 2). In addition, a comparison of the iodine level ratio between PAP and 60 s (60s/PAP ratio) for TLIV and TLIV/LV before and after treatment was performed between the two groups.ResultsIn total, 24 patients with acute PE were analyzed using DLCT before and after DOAC therapy. The TLIV (60s/PAP ratio; median 1.34, interquartile range [IQR]=1.18-1.72) of group 1 (n = 16) was significantly higher (P = 0.002) than the TLIV (60s/PAP ratio; median = 0.91, IQR = 0.79-0.99) of group 2 (n = 8).ConclusionMeasuring the iodine maps of all lungs showed promise as the level of lung perfusion after DOAC treatment appeared to reflect the treatment effect in acute PE.