Effect of Balloon Pulmonary Angioplasty on Homogenization of Lung Perfusion Blood Volume by Dual-Energy Computed Tomography in Patients with Chronic Thromboembolic Pulmonary Hypertension

OBJECTIVE

Balloon pulmonary angioplasty (BPA) is used to treat patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH); the goal is to improve pulmonary perfusion. We aimed to evaluate lung perfusion blood volume (PBV) with haemodynamic and exercise-capacity parameters to assess the efficacy of BPA in the treatment of CTEPH.

METHODS

We retrospectively studied 33 patients over a 6-year period. DECT pulmonary angiography was performed before and after BPA. DECT provided iodine distribution maps; whole-lung and regional PBV images and quantification were generated using post-processing software. A mosaic pattern suggesting perfusion inhomogeneity is typical in CTEPH. Hypothetically, BPA treatment would promote homogenization that would be reflected in the calculated standard deviation.

RESULTS

Lung perfusion images showed decreased heterogeneity after BPA. There was a significant difference before and after BPA in the whole-lung PBV and in the regional standard deviation for pulmonary arterial pressure (R = 0.37, p = 0.032 and R = 0.57, p = 0.006), pulmonary vascular resistance (R = 0.51, p = 0.023 and R = 0.60, p = 0.002), transtricuspid pressure gradient (R = 0.50, p = 0.0028 and R = 0.61, p = 0.0001), brain natriuretic peptide (R = 0.54, p = 0.0012 and R = 0.46, p = 0.0078), and 6-min walking distance (R = 0.59, p = 0.003 and R = 0.26, p = 0.14). The effects were especially pronounced after the first BPA procedure.

CONCLUSION

Decreased lung heterogeneity may suggest BPA efficacy in treating CTEPH. After BPA treatment, improved lung PBV and improved regional standard deviation showed a strong positive correlation with haemodynamic parameters and exercise capacity, which also suggests that BPA is effective in treating CTEPH.

Detection of pulmonary fat embolism with dual-energy CT: an experimental study in rabbits

OBJECTIVES

To evaluate the use of dual-energy CT imaging of the lung perfused blood volume (PBV) for the detection of pulmonary fat embolism (PFE).

METHODS

Dual-energy CT was performed in 24 rabbits before and 1 hour, 1 day, 4 days and 7 days after artificial induction of PFE via the right ear vein. CT pulmonary angiography (CTPA) and lung PBV images were evaluated by two radiologists, who recorded the presence, number, and location of PFE on a per-lobe basis. Sensitivity, specificity, and accuracy of CTPA and lung PBV for detecting PFE were calculated using histopathological evaluation as the reference standard.

RESULTS

A total of 144 lung lobes in 24 rabbits were evaluated and 70 fat emboli were detected on histopathological analysis. The overall sensitivity, specificity and accuracy were 25.4 %, 98.6 %, and 62.5 % for CTPA, and 82.6 %, 76.0 %, and 79.2 % for lung PBV. Higher sensitivity (p < 0.001) and accuracy (p < 0.01), but lower specificity (p < 0.001), were found for lung PBV compared with CTPA. Dual-energy CT can detect PFE earlier than CTPA (all p < 0.01).

CONCLUSION

Dual-energy CT provided higher sensitivity and accuracy in the detection of PFE as well as earlier detection compared with conventional CTPA in this animal model study.

KEY POINTS

• Fat embolism occurs commonly in patients with traumatic bone injury. • Dual-energy CT improves diagnostic performance for pulmonary fat embolism detection. • Dual-energy CT can detect pulmonary fat embolism earlier than CTPA.