Incidence and morphological characteristics of the reversed halo sign in patients with acute pulmonary embolism and pulmonary infarction undergoing computed tomography angiography of the pulmonary arteries / Incidência e características morfológicas do sinal do halo invertido em pacientes com tromboembolismo pulmonar agudo e infarto pulmonar submetidos a angiotomografia de artérias pulmonares

ABSTRACT Objective: To determine the incidence of the reversed halo sign (RHS) in patients with pulmonary infarction (PI) due to acute pulmonary embolism (PE), detected by computed tomography angiography (CTA) of the pulmonary arteries, and to describe the main morphological features of the RHS. Methods: We evaluated 993 CTA scans, stratified by the risk of PE, performed between January of 2010 and December of 2014. Although PE was detected in 164 scans (16.5%), three of those scans were excluded because of respiratory motion artifacts. Of the remaining 161 scans, 75 (46.6%) showed lesions consistent with PI, totaling 86 lesions. Among those lesions, the RHS was seen in 33 (38.4%, in 29 patients). Results: Among the 29 patients with scans showing lesions characteristic of PI with the RHS, 25 (86.2%) had a single lesion and 4 (13.8%) had two, totaling 33 lesions. In all cases, the RHS was in a subpleural location. To standardize the analysis, all images were interpreted in the axial plane. Among those 33 lesions, the RHS was in the right lower lobe in 17 (51.5%), in the left lower lobe in 10 (30.3%), in the lingula in 5 (15.2%), and in the right upper lobe in 1 (3.0%). Among those same 33 lesions, areas of low attenuation were seen in 29 (87.9%). The RHS was oval in 24 (72.7%) of the cases and round in 9 (27.3%). Pleural effusion was seen in 21 (72.4%) of the 29 patients with PI and the RHS. Conclusions: A diagnosis of PE should be considered when there are findings such as those described here, even in patients with nonspecific clinical symptoms.

RESUMO Objetivo: Verificar a incidência do sinal do halo invertido (SHI) associado a infartos pulmonares (IP) relacionados ao tromboembolismo pulmonar (TEP) agudo, identificado por angiotomografia (angio-TC) de artérias pulmonares, e demonstrar as principais características morfológicas do SHI. Métodos: Foram avaliadas 993 angio-TCs, após estratificação de risco clínico para TEP entre janeiro de 2010 e dezembro de 2014. TEP foi encontrado em 164 pacientes (16,5%), sendo que três exames foram descartados devido a artefatos de movimentação respiratória. Dos 161 exames restantes, em 75 (46,6%) foram identificadas imagens compatíveis com IP, totalizando 86 lesões; o SHI foi observado em 33 (38,4% dos pacientes) dessas lesões. Resultados: Dos 29 pacientes com lesões características de IP com o SHI, 25 pacientes (86,2%) apresentavam lesão única e 4 (13,8%), lesão dupla. Todas as imagens compatíveis com SHI eram de localização subpleural. Para padronizar a análise, todas as imagens foram interpretadas no plano axial. Em relação à distribuição lobar das 33 lesões, o SHI estava localizado no lobo inferior direito, em 17 (51,5%); no lobo inferior esquerdo, em 10 (30,3%); na língula, em 5 (15,2%) e no lobo superior direito, em 1 (3,0%). Áreas de baixa atenuação no interior dos IPs com o SHI foram observadas em 29 das 33 lesões (87,9%). O SHI apresentava formato ovalado em 24 (72,7%) dos casos e formato arredondado, em 9 (27,3%). Derrame pleural foi encontrado associado aos IP com o SHI em 21 pacientes (72,4%). Conclusões: O achado de imagens com essas características, mesmo em pacientes com sintomatologia inespecífica, deve alertar para a possibilidade do diagnóstico de TEP.

A Case Report: Cavitary Infarction Caused by Pulmonary Tumor Thrombotic Microangiopathy in a Patient with Pancreatic Intraductal Papillary Mucinous Neoplasm

Pulmonary tumor embolism is commonly discovered at autopsy, but is rarely suspected ante-mortem. Microangiopathy is an uncommon and distinct form of simple tumor pulmonary embolism. Here, we present a 52-year-old male with tumor thrombotic microangiopathy and pulmonary infarction, which might have originated from intraductal papillary mucinous tumor of the pancreas. Multiple wedge-shaped consolidations were found initially and aggravated with cavitation. These CT features of pulmonary infarction were pathologically confirmed to result from pulmonary tumor thrombotic microangiopathy.

Lung Infarction due to Pulmonary Vein Stenosis after Ablation Therapy for Atrial Fibrillation Misdiagnosed as Organizing Pneumonia: Sequential Changes on CT in Two Cases

Pulmonary vein (PV) stenosis is a complication of ablation therapy for arrhythmias. We report two cases with chronic lung parenchymal abnormalities showing no improvement and waxing and waning features, which were initially diagnosed as nonspecific pneumonias, and finally confirmed as PV stenosis. When a patient presents for nonspecific respiratory symptoms without evidence of infection after ablation therapy and image findings show chronic and repetitive parenchymal abnormalities confined in localized portion, the possibility of PV stenosis should be considered.