Diagnostic accuracy of perfusion-weighted phase-resolved functional lung magnetic resonance imaging in patients with chronic pulmonary embolism

PurposeThis study aimed to evaluate the diagnostic performance of perfusion-weighted phase-resolved functional lung (PW-PREFUL) magnetic resonance imaging (MRI) in patients with chronic pulmonary embolism (CPE).Materials and methodsThis study included 86 patients with suspected chronic thromboembolic pulmonary hypertension (CTEPH), who underwent PREFUL MRI and ventilation/perfusion (V/Q) single-photon emission computed tomography/computed tomography (SPECT/CT). PREFUL MRI was performed at 1.5 T using a balanced steady-state free precession sequence during free breathing. Color-coded PW images and quantitative parameters were obtained by postprocessing. Meanwhile, V/Q SPECT/CT imaging was performed as a reference standard. Hypoperfused areas in the lungs were scored for each lobe and segment using V/Q SPECT/CT images and PW-PREFUL MR images, respectively. Normalized perfusion (QN) and perfusion defect percentage (QDP) were calculated for all slices. For intra- and interobserver variability, the MRI images were analyzed 2 months after the first analysis by the same radiologist and another radiologist (11 years of lung MRI experience) blinded to the results of the first reader.ResultsOf the 86 enrolled patients, 77 met the inclusion criteria (36 diagnosed with CPE using V/Q SPECT/CT and 41 diagnosed with non-CPE etiology). For the PW-PREFUL MRI, the sensitivity, specificity, accuracy, and positive and negative predictive values for the diagnosis of CPE were 97, 95, 96, 95, and 98% at the patient level; 91, 94, 93, 91, and 94% at the lobe level, and 85, 94, 92, 88, and 94% at the segment level, respectively. The detection of segmental and subsegmental hypoperfusion using PW-PREFUL MRI revealed a moderate agreement with V/Q SPECT/CT (κ = 0.65; 95% confidence interval: 0.61–0.68). The quantitative results indicated that the QN was lower in the CPE group than in the non-CPE group [median score (interquartile range, IQR) 6.3 (2.8–9.2) vs. 13.0 (8.8–16.7), p < 0.001], and the QDP was higher [median score (IQR) 33.8 (15.7–51.7) vs. 2.2 (1.4–2.9), p < 0.001].ConclusionPREFUL MRI could be an alternative test to detect CPE without requiring breath-hold, contrast agents, or ionizing radiation

Endothelial Microparticles in Mild Chronic Obstructive Pulmonary Disease and Emphysema. The Multi-Ethnic Study of Atherosclerosis Chronic Obstructive Pulmonary Disease Study

Rationale: Basic research implicates alveolar endothelial cell apoptosis in the pathogenesis of chronic obstructive pulmonary disease (COPD) and emphysema. However, information on endothelial microparticles (EMPs) in mild COPD and emphysema is lacking. Objectives: We hypothesized that levels of CD31+ EMPs phenotypic for endothelial cell apoptosis would be elevated in COPD and associated with percent emphysema on computed tomography (CT). Associations with pulmonary microvascular blood flow (PMBF), diffusing capacity, and hyperinflation were also examined. Methods: The Multi-Ethnic Study of Atherosclerosis COPD Study recruited participants with COPD and control subjects age 50–79 years with greater than or equal to 10 pack-years without clinical cardiovascular disease. CD31+ EMPs were measured using flow cytometry in 180 participants who also underwent CTs and spirometry. CD62E+ EMPs phenotypic for endothelial cell activation were also measured. COPD was defined by standard criteria. Percent emphysema was defined as regions less than −950 Hounsfield units on full-lung scans. PMBF was assessed on gadolinium-enhanced magnetic resonance imaging. Hyperinflation was defined as residual volume/total lung capacity. Linear regression was used to adjust for potential confounding factors. Measurements and Main Results: CD31+ EMPs were elevated in COPD compared with control subjects (P = 0.03) and were notably increased in mild COPD (P = 0.03). CD31+ EMPs were positively related to percent emphysema (P = 0.045) and were inversely associated with PMBF (P = 0.047) and diffusing capacity (P = 0.01). In contrast, CD62E+ EMPs were elevated in severe COPD (P = 0.003) and hyperinflation (P = 0.001). Conclusions: CD31+ EMPs, suggestive of endothelial cell apoptosis, were elevated in mild COPD and emphysema. In contrast, CD62E+ EMPs indicative of endothelial activation were elevated in severe COPD and hyperinflation

Chronic Obstructive Pulmonary Disease (COPD) is associated with pulmonary artery stiffness - the MESA COPD study

This study seeks to evaluate indices of pulmonary artery (PA) stiffness in patients with COPD and compare with normal controls. We hypothesize that patients with COPD would have increased pulmonary artery stiffness. To test this we determine the pulmonary artery area change (distensibility in %) by cardiac MRI and relate the distensibility to a wide range of severity of COPD. The MESA COPD Study recruited 290 patients (135 patients of various COPD severity and 155 controls) from four field centers in the US, age 50-79 years with ≥10 pack-years of smoking, all free of clinical cardiovascular disease. COPD was defined on post-bronchodilator spirometry by GOLD criteria (FEV1/FVC 80% = mild, 50-80%=moderate, <50%=severe). All participants underwent full-lung CTs. Percent emphysema was defined as the percentage of total voxels within the lung field that fell below -910 Hounsfield units. MRI studies were performed using 1.5T scanners. To measure ventricular function, the entire heart was imaged in short-axis orientation using a retrospectively gated steady-state free precession sequence. Phase-contrast images of the pulmonary arteries were obtained using a segmented fast gradient echo sequence with free breathing and analyzed quantitatively using dedicated software (FLOW, Medis). Distensibility of the pulmonary vessels (in %) are measured by the following formula, 100×(maximum PA area-minimum PA area)/minimum PA area. The base model (model 1) was adjusted for age, gender, height, weight, race/ethnicity and cohort of selection, given relationships of COPD severity to the pulmonary distensibility. We then additionally adjusted for smoking status, pack-years, diabetes mellitus, hypertension, oxygen saturation, LDL, HDL and statin use (model 2). Table 1 summarizes the clinical characteristics of 290 participants stratified by COPD severity. Distensibility of the main, right and left PA was reduced in COPD compared to controls in both models (Table 2). Main and right pulmonary distensibilities were inversely related to percent emphysema after minimal adjustment (model 1, P=0.21 and 0.07, respectively) and similar trends with statistical significance in the full model (model 2, P=0.049 and 0.01, respectively). Pulmonary distensibilities was positively associated with the percent predicted FEV1 but only left PA attain statistical significance after base adjustment (model 1, P=0.047). We conclude that in COPD patients without overt cardiovascular disease, pulmonary artery distensibility is reduced. Higher pulmonary arterial stiffness also correlated with the percent emphysema on CT scan and FEV1