Linking CT and SPECT based analysis for quantitative follow-up of vascular perfusion defects in COVID-19

COVID-19 still affects a large population worldwide with possible post-traumatic sequelae requiring long-term patient follow-up for the most severe cases. The lung is the primary target of severe acute respiratory syndrome coronavirus 2 (SARS- CoV-2) infection. In particular, the virus affects the entire pulmonary vascular tree from large vessels to capillaries probably leading to an abnormal vascular remodeling. In this study we investigated two modalities for assessing this remodeling, SPECT perfusion scintigraphy and computed tomography, the latter enabling the computation of vascular remodeling patterns. We analyzed on a cohort of 30 patients the relationship between vascular remodeling and perfusion defects in the peripheral lung area, which is a predominant focus of the COVID-19 infectious patterns. We found that such relationship exists, demonstrated by moderate significant correlations between SPECT and CT measures. In addition, a vascular remodeling index derived from the z-score normalized peripheral CT images showed a moderate significant correlation with the diffusing capacity of the lung for carbon monoxide (DLCO) measures. Altogether these results point CT scan as a good tool for a standardized, quantitative, and easy-to-use routine characterization and follow-up of COVID-19-induced vascular remodeling. An extensive validation of these results will be carried out in the near future on a larger cohort. © 2023 SPIE.

Characterization of respiratory sequelae following SARSCoV-2 infection, a monocenter study

Introduction: During the acute phase of SARS-CoV-2 infection, alveolar and microvascular damages are observed in some patients. These lesions are promoted by hyper inflammation and immunothrombosis, respectively. While dyspnea is a very prevalent symptom following SARS-CoV-2 infection, the consequences on the lung are currently poorly documented. Aims and objectives: We hypothesized that patients retained parenchymal and also vascular sequelae after the infection. This single-center ambispective study aimed to characterize these sequelae after the infection. Method(s): All patients hospitalized at the University Hospital of Caen for a PCR-proven SARS-CoV-2 infection were offered a follow-up including a clinical evaluation and the realization of complete LFT, non-injected CT scan, ventilation/perfusion single-photon emission computed tomography (SPECT), and a cardiopulmonary exercise testing (CET). This assessment was performed within 6 to 9 months after the infection. Result(s): 105 patients were included. At 6-9 months after infection, 71% of our patients retained radiological abnormalities, mainly ground glass and/or reticulations. LFT revealed that 21.3% of patients had abnormal FVC (<80%) and 51.2% of patients had abnormal DLCO (<80%). SPECT showed mismatched defects for 15% of patients. Finally, CET showed that 28.6% of the patients had an exercise limitation and 25% showed an abnormality of the vascular parameters. Conclusion(s): These preliminary data suggest the persistence of vascular and parenchymal abnormalities in a significant proportion of patients at 6-9 months after SARS-CoV-2 infection.

Modelisation du remodelage vasculaire post-COVID-19 a partir de l'analyse bio-informatique de scanner thoracique et de scanner thoracique non injecte

Declaration de liens d'interets: Les auteurs declarent ne pas avoir de liens d'interets. Copyright © 2022

Multiparameter analysis of vascular remodeling in post-Acute sequelae of COVID-19

The COVID-19 infection, a current worldwide health concern, manifests as an alveolar-interstitial pneumonia with unknown long-Term evolution. It is also associated with vascular dysfunction and shows a vascular remodeling with a changed balance between small-and large-caliber vessels. In this study, we question the existence of residual vascular alteration in post-Acute sequelae of COVID-19 (PASC) by investigating possible associations between vascular remodeling biomarkers extracted from CT and functional, radiological and morphological parameters. The used vascular biomarkers concern the blood volume ratio of vessels with cross-section area inferior to 5 mm2 versus vessels of crosssection area inferior to 50 mm2 (BV5/BV50), an index of local peripheral vascular density and a peripheral composite vascular remodeling index, both measured in the antero-postero-lateral lung periphery (excluding mediastinal region). As a functional parameter, diffusing capacity of the lung for carbon monoxide (DLCO) is a measure depending on the vascular perfusion and the amount of interstitial thickening, a decreased DLCO value suggesting altered vascular perfusion. Imaging biomarkers can be extracted from the analysis of perfusion lung scintigraphy or CT scan. Some of them are included in our study. Radiological features include CT attenuation as a measure of persistence of ground glass opacity and development of changes suggestive to look for fibrosis, such as reticulations. As additional morphological parameter, lung deformation observed between inspiration/expiration maneuvers may be suggestive of the presence of reticulations inducing lung stiffness and breathing deficiency. The investigation of associations between vascular remodeling biomarkers obtained from CT and the above functional, radiological and morphological parameters revealed moderate to strong correlations highlighting the ability to capture the persistence of vascular alterations in PASC in relation with the development of fibrotic patterns, which is a promising direction for future research. © 2022 SPIE.

Séquelles fonctionnelles, vasculaires et parenchymateuses à 6–9 mois d’une infection au SarsCov2

Introduction Alors que la dyspnée est un symptôme très prévalent au décours de l’infection au SARS-Cov2, les conséquences sur la fonction respiratoire de cette infection sont aujourd’hui mal connues. Cette étude prospective monocentrique vise à caractériser les séquelles fonctionnelles, vasculaires et parenchymateuses à 6–9 mois d’une infection au SARS Cov2. Méthodes Tous les patients pris en charge en charge au CHU de Caen pour une infection liée au SARS-CoV-2, se sont vus proposer un suivi comportant une évaluation clinique et la réalisation d’épreuves fonctionnelles respiratoires complètes, d’une tomodensitométrie sans injection en coupes fines d’une scintigraphie de perfusion ventilation et une épreuve d’effort. Ce bilan était réalisé dans les 6 à 9 mois au décours de l’infection. Les patients avec une suspicion d’infection non documentée par PCR ou perdus de vue lors du suivi étaient exclus de l’étude. Résultats Au total, 105 patients ont été inclus dans notre étude. À l’exception de l’épreuve d’effort, les données du bilan ont pu être collectées pour la majorité des patients. Lors de l’épisode infectieux, 62,9 % des patients ont été pris en charge en soins continus ou réanimation. L’ensemble des patients a bénéficié d’un traitement par dexamethasone. La majorité des patients étaient des hommes (67,6 %), avec un âge moyen de 63,7 ans. Les comorbidités les plus fréquentes étaient l’obésité (45,7 %), l’hypertension artérielle (41,9 %) et le diabète de type 2 (39 %). À 6–9 mois de l’infection, 71 % des patients présentaient des anomalies radiologiques, principalement a type de verre dépoli résiduel et/ou de réticulations. Sur le plan fonctionnel, 18,6 % des patients présentaient une CVF anormale (<80 %) et 51,2 % des patients présentaient une DLCO anormale (<80 %). Sur le plan vasculaire, la scintigraphie de ventilation/perfusion a retrouvé a mis en évidence chez 15 % d’entre eux un défect perfusionnel non concordant. 56 patients ont réalisé une épreuve d’effort. 28,6 % des patients ont présenté une limitation de leur capacité d’effort. Une limitation ventilatoire a été retrouvée chez 10,7 % des patients, un déconditionnement musculaire chez 17,9 % des patients, une anomalie vasculaire chez 25,0 %. Un syndrome d’hyperventilation a été identifié chez 23,2 % des patients. Conclusion Ces données préliminaires suggèrent la persistance d’anomalies vasculaires, parenchymateuses associées pour une proportion importante de patients à 6–9 mois d’une infection au SARS-Cov2 dans notre cohorte.