ABSTRACT
Objective To evaluate the lung V/Q imaging in the diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH).Methods Seventy-six patients (46 males,30 females,age 27-84 y) with clinically suspected CTEPH who had undergone lung V/Q imaging,CT pulmonary angiography (CTPA),pulmonary angiography (PA) and right heart cardiac catheterization were studied.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of lung V/Q imaging in detecting CTEPH were calculated and compared with those of CTPA.The x2 test was used for statistical analysis with SPSS 11.5.The distribution of involvement of segments in 47 patients with CTEPH was analyzed.Results Forty-seven patients had a final diagnosis of CTEPH and 29 had non-CTEPH etiology.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of lung V/Q imaging were 97.9％ (46/47),86.2％ (25/29),93.4％ (71/76),92.0％ (46/50) and 96.2％ (25/26),while those of CTPA were 78.7％ (37/47),93.1％ (27/29),84.2％ (64/76),94.9％ (37/39) and 73.0％ (27/37),respectively.The sensitivity (x2 =5.818,P=0.012) and negative predictive value (x2 =5.693,P =0.017) for lung V/Q imaging were significantly higher than those of CTPA.V/Q imaging could identify patients with CTEPH from those with idiopathic PAH and familial PAH based on the almost normal ventilation imaging.The lung perfusion SPECT imaging detected 585 (62.2％) of involved segments among 940 segments in 47 patients with CTEPH,with an average of 12.4 involved segments in each patient.The number of involved segments in the right lung was significantly higher than that in the left lung (36.2％ (340/940) vs 26.1％ (245/940) ; x2 =40.85,P＜0.01).Conclusions Lung V/Q imaging plays an important role in diagnosis of CTEPH and in identification of CTEPH from other types of PAH.A normal V/Q imaging can effectively exclude CTEPH.In addition,V/Q imaging can provide more diagnostic information in patients with a clinical suspicion of CTEPH who had negative results by CTPA and PA.