A technique for assessing pulmonary perfusion in patients with previously treated COVID-19 pneumonia: clinical controlled non-randomized study

Abstract

INTRODUCTION: Evaluating pulmonary lung perfusion in patients with previously treated COVID-19 infection may lead to a better understanding of long-term consequences of the disease, as well as may identify the changes determined by their symptoms. Further research is required for optimization of lung perfusion’s design parameters’ methods in order to implement those in clinical practice.OBJECTIVE: To determine the possibilities of an alternative method for evaluation of relative lung perfusion using three-dimensional ultrafast contrast-enhanced MRI on patients with previously treated COVID-19 pneumonia.MATERIALS AND METHODS: We examined 100 patients (28 male and 72 female, aged 22 to 70) who had laboratory-confirmed COVID-19 infection. The research was conducted using the three-dimensional ultrafast dynamic contrast-enhanced MRI based on 3D T1-weighted images. During the postprocessing, we received the values of rPBF (relative pulmonary blood flow), rPBV (relative pulmonary blood volume), and rMTT (relative mean transit time).Statistics. For non-linear dependence modelling we used natural spline transformation for time and interaction effect with a group. Intergroup comparison on integral measures was based on Kruskall-Wallis test (χ2), pair comparisons were based on Conover’s test (Δ). For multiple hypothesis testing correction, we used the false discovery rate (FDR). Comparisons were determined as statistically significant when p<0.05.RESULTS: The differences in obtained values of lung perfusion among patient groups were confirmed both quantitatively (by rMTT, rPBV, rPBF) and qualitatively (by building the curves of contrast agent accumulation). Patients with previously treated COVID-19 demonstrate slower contrast agent transit and increased relative lung blood volume. Their accumulation curves have qualitative differences as well.DISCUSSION: We suggest a new method of evaluation of lung perfusion indicators in patients with previously treated COVID-19. We conducted an intergroup analysis based on the degree of lung damage during the acute phase of COVID-19 (with no infiltrativechanges, with minor lung damage, and major lung damage). The intergroup differences found are more significant for patients with lung damage (both minor and major) than for patients with no infiltrative lung changes during the acute phase of COVID-19.CONCLUSION: This method of evaluation of pulmonary perfusion is able to adequately characterize the functional lung conditions in patients with previously treated COVID-19 pneumonia. The chosen model is the most optimal.