RESUMEN
Background: High-altitude pulmonary hypertension (HAPH), as the group 3 pulmonary hypertension, has been less studied so far. The limited medical conditions in the high-altitude plateau are responsible for the delay of the clinical management of HAPH. Objectives: This study aims to identify the imaging characteristics of HAPH and explore noninvasive assessment of mean pulmonary arterial pressure (mPAP) based on computed tomography angiography (CTA). Methods: Twenty-five patients with suspected HAPH were enrolled. Right heart catheterization (RHC) and pulmonary angiography were performed. Echocardiography and CTA image data were collected for analysis. A multivariable linear regression model was fit to estimate mPAP (mPAPpredicted). A Bland-Altman plot and pathological analysis were performed to assess the diagnostic accuracy of this model. Results: Patients with HAPH showed slow blood flow and coral signs in lower lobe pulmonary artery in pulmonary arteriography, and presented trend for dilated pulmonary vessels, enlarged right atrium, and compressed left atrium in CTA (P for trend <0.05). The left lower pulmonary artery-bronchus ratio (odds ratio: 1.13) and the ratio of right to left atrial diameter (odds ratio: 1.09) were significantly associated with HAPH, and showed strong correlation with mPAPRHC, respectively (r = 0.821 and r = 0.649, respectively; all P < 0.0001). The mPAPpredicted model using left lower artery-bronchus ratio and ratio of right to left atrial diameter as covariates showed high correlation with mPAPRHC (r = 0.907; P < 0.0001). Patients with predicted HAPH also had the typical pathological changes of pulmonary hypertension. Conclusions: Noninvasive mPAP estimation model based on CTA image data can accurately fit mPAPRHC and is beneficial for the early diagnosis of HAPH.
RESUMEN
A noncontact, noninvasive, electrical permittivity imaging technique is proposed for monitoring loosening of osseointegrated prostheses and bone fracture. The proposed method utilizes electrical capacitance tomography (ECT), which employs a set of noncontact electrodes, arranged in a circular fashion around the imaging area, for electrical excitations and measurements. An inverse reconstruction algorithm was developed and implemented to reconstruct the electrical permittivity distribution of the interrogated region from boundary capacitance measurements. In this study, osseointegrated prosthesis phantoms were prepared using plastic rods and Sawbone femur specimens, which were subjected to prosthesis loosening and fracture monitoring tests. The results demonstrated that the spatial location and extent of prosthesis loosening and bone fracture could be estimated from the ECT reconstructed permittivity maps. The resolution of the reconstructed images was further enhanced by a limited region tomography algorithm, and its accuracy in terms of identifying the severity, location, and shape of bone fracture was also investigated and compared with conventional full region tomography.