Background: Chronic thromboembolic pulmonary hypertension (CTEPH) is pulmonary obstructive vascular disease. But there were few methods to quantify lung blood perfusion. In dual-energy CT (DECT), two image datasets are acquired in the same anatomic location using two different tube potentials. DECT can produce a more sensitive iodine distribution map image than conventional CT, which enable us to quantify blood perfusion in lung fields. There were few reports showing the clinical significance of DECT in CTEPH.
Methods: We enrolled 59 consecutive CTEPH patients who underwent DECT from Jan. 2015 to Feb. 2017. We evaluated the relations between DECT parameter as lung pulmonary blood volume (PBV) and clinical parameters from 6-min walk distance (6MWD), respiratory function test, cardiopulmonary exercise test (CPX), and right heart catheterization (RHC).
Results: In 59 patients (female 41, mean age 60.0±13.6 years old), two patients were WHO functional class (WHO-Fc) IV, 28 were WHO-Fc III, 23 were WHO-Fc II, six were WHO-Fc I. 28 patients were evaluated at pre-treatment, nine at post pulmonary endarterectomy (PEA), 18 at post balloon pulmonary angioplasty (BPA), and four at post hybrid therapy (PEA and BPA). The average of PBV were 25.4±7.4 Hounsfield Unit. Mean pulmonary arterial pressure (mPAP) were 29.5±12.9 mmHg, pulmonary vascular resistance (PVR) were 553±404 dyne*sec/cm5, cardiac index were 2.3±0.7 l/min/m2. The value of PBV was well reflected with WHO-Fc classification. (I/II/III/IV=31.8±6.4/27.1±7.4/22.8±6.2/23.5±13.4; ANOVA p=0.019), and was significantly correlated with mPAP (r = -0.57, p < 0.01), PVR (r = -0.60, p < 0.01), VE/VCO2 slope (r =- 0.47, p < 0.01), BNP level (r = -0.60, p < 0.01).
Conclusion: PBV was positively correlated with symptom, hemodynamics, exercise capacity, and BNP level in the patients of CTEPH, suggesting that PBV by DCET can work as a new management index from a perspective of pulmonary blood perfusion.