Signo de la diana en COVID-19, significado radiológico y aportación diagnóstica de la tomosíntesis digital torácica

Introduction

Our objectives are to describe the imaging features, clinical characteristics, laboratory values and prognosis related to the target sign (TS) in COVID-19, as well as to determine whether digital tomosynthesis (DTS) of the chest has diagnostic advantages over radiography in this context.

Material and methods

Retrospective, descriptive, single-centre, case series study, accepted by our ethical committee. Radiological, clinical, analytical and follow-up characteristics of patients with COVID-19 and TS on radiography and DTS between November 2020 and January 2021 were analysed.

Results

Eleven TS were collected in seven patients, with a median age of 35 years, 57% male. All TS presented with a central nodule and a peripheral ring, and in at least 82%, the lung in between was of normal density. All TS were located in peripheral, basal regions and 91% in posterior regions. TS were multiple in 43%. The peripheral rings in contiguous TS were joined. Other pneumonia-related findings were identified in 86% of patients. Detection of the TS 82% higher in DTS than radiography. Only one patient underwent a CT pulmonary angiography, which was positive for acute pulmonary embolism. Seventy-one per cent presented with pleuritic pain. Laboratory values revealed no significant findings and the TS did not indicate a worse prognosis.

Conclusions

TS in COVID-19 predominates in peripheral and basal regions and can be multiple. Pulmonary embolism was detected in one case. It occurs in young people, frequently with pleuritic pain and does not lead to a worse prognosis. DTS detects TS in over 80% more cases than radiography.