COVID-19 pneumonia and target sign

A 49-year-old man came to our emergency department with a 2-day history of fever, cough, anosmia, ageusia and odynophagia. His past medical history included hypertension. At the time of this presentation, chest computed tomography revealed peripheral and bilateral ground-glass opacities, with some visible intralobular lines – typical findings of pneumonia caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In addition, some findings revealed the target sign (Figure 1). The patient’s supportive treatment was continued, and reverse-transcriptase polymerase chain reaction (RT-PCR) confirmed the infection by SARS-CoV-2.

Figure 1
Chest computed tomography imaging (A) axial, (B) sagittal oblique, and (C and D) coronal oblique show the target sign characterized by multiple concentric ring-like opacities, with a central nodular peribronchovascular opacity, in a 49-year-old man with COVID-19 pneumonia. Note the reversed halo sign in the left upper lobe

The target sign has been recently described and associated with organizing pneumonia and vascular features related to the viral infection.(¹-³) It is characterized by a nodular opacity in the center of a ring-like opacity, which can have ground-glass or consolidation attenuation, as well multiple concentric ring-like opacities.(⁴) When only with one or two ring-like opacities, this sign is not specific to COVID-19, and the differential diagnosis includes conditions other than organizing pneumonia, such as metastasis and post-radiofrequency ablation zone.(⁵,⁶) However, the manifestation with multiple concentric ring-like opacities (Figure 1) has only been reported so far in patients with COVID-19 pneumonia.(⁴)

We emphasize the importance of familiarizing radiologists with imaging findings of COVID-19 pneumonia to contribute to its diagnostic suspicion. The description of new radiological patterns, so far infrequent or little known, is of great value in the scenario of the SARS-CoV-2 pandemic, since the use of chest computed tomography has increased significantly in patients suspected to have COVID-19 pneumonia. It is noteworthy that further studies are still required to better assess the target sign and its accuracy in SARS-CoV-2 infection.

REFERENCES

• ¹
  Lang M, Som A, Carey D, Reid N, Mendoza DP, Flores EJ, et al. Pulmonary vascular manifestations of COVID-19 pneumonia. Radiol Cardiothorac Imaging. 2020;2(3):e200277.
• ²
  Ackermann M, Verleden SE, Kuehnel M, Haverich A, Welte T, Laenger F, et al. Pulmonary vascular endothelialitis, thrombosis, and angiogenesis in Covid-19. N Engl J Med. 2020;383(2):120-8.
• ³
  Pogatchnik BP, Swenson KE, Sharifi H, Bedi H, Berry GJ, Guo HH. Radiology-pathology correlation demonstrating organizing pneumonia in a Patient Who Recovered from COVID-19. Am J Respir Crit Care Med. 2020;202(4):598-9.
• ⁴
  Farias LP, Souza FH, Teles GB. The target sign and its variant in COVID-19 Pneumonia. Radiol Cardiothorac Imaging. 2020;2(4):e200435.
• ⁵
  Marchiori E, Silva JA, Amorim VB, Zanetti G. Is the CT target sign specific to COVID-19 pneumonia? J Bras Pneumol. 2020;46(6):e20200541.
• ⁶
  Abtin FG, Eradat J, Gutierrez AJ, Lee C, Fishbein MC, Suh RD. Radiofrequency ablation of lung tumors: imaging features of the postablation zone. Radiographics. 2012;32(4):947-69. Review.

Publication Dates

• Publication in this collection
  17 Dec 2021
• Date of issue
  2021

History

• Received
  27 Feb 2021
• Accepted
  24 Apr 2021