Detection of pulmonary embolism with gadolinium-enhanced dual energy CT: an experimental study / 中华放射学杂志

ABSTRACT

ObjectiveTo evaluate the feasibility of gadolinium-enhanced dual energy CT pulmonary angiography (CTPA) in detecting pulmonary embolism (PE).MethodsIn vitro dual energy CT of phantoms of gadolinium and iodinated contrast agents with different diluted ratio was performed,and CT values were measured at different tube voltages.Ten rabbits which were grouped into 3 ml/kg and 5 ml/kg groups underwent dual energy CT scan.CT values of pulmonary artery trunk and the first branch of pulmonary artery were measured.Sponge gelatin were injected into the femoral vein of 6 rabbits to make PE model next day,then lungs were re-imaged with dual energy CT 2 h after embolization.Creatinine was repeatedly measured before and one day after injection of gadolinium via ear marginal vein or femoral vein sampling.One-way ANOVA test and independent student t test were used to analyze the difference of pulmonary artery enhancement between different groups.Results ( 1 ) Compared with iodinated contrast agent,CT value of gadolinium-based contrast agent at 80 kV was higher than those at 140 kV and averageweighted 120 kV.(2) At 140,80,and average weighted 120 kV,CT values of pulmonary artery trunk [CT values were (463.1 ± 118.0),(664.2 ± 188.0),(522.9 ± 137.7) HU] and of the first branch of pulmonary artery [ CT values were (445.1 ± 82.3 ),(606.7 ± 207.2),(493.4 ± 117.3 ) HU ] were higher than those at 3 ml/kg [ CT value of pulmonary artery trunk was ( 258.1 ± 55.1 ),( 384.0 ± 92.3 ),(295.4 ± 73.6) HU,CT value of the first branch of pulmonary artery (245.0 ± 73.2 ),( 309.1 ± 94.2),(263.8 ±78.5) HU;all P ＜0.05].CT values of pulmonary artery trunk and the first branch of pulmonary artery at 80 kV were higher than those at 140 kV and average-weighted 120 kV ( pulmonary artery trunkF =6.004,P =0.005 ; the first branch of pulmonary artery F =4.374,P =0.018).In 6 rabbits,CTPA showed the enhancement cut-off of bilateral pulmonary arteries,gadolinium mapping showed decreased perfusion in the corresponding lung lobes,manifested as blue on color-coded map,while normal lung was color coded as red or yellow.Creatinine was higher by 6.7％ and 20.6％ for group 3 ml/kg and 5 ml/kg.ConclusionsWith similar X-ray attenuation characteristics as iodine,gadolinium-based contrast agent can be used to pulmonary contrast-enhanced dual energy CT imaging,simultaneously providing both CTPA and gadolinium maps to detect PE.