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Consider septic pulmonary embolism in patients with IV substance use disorder presenting with reversed halo sign
Dr KK Aggarwal,  04 November 2019
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Septic pulmonary embolism (PE) should be considered in the differential diagnosis of patients with IV substance use disorder presenting with reversed halo sign, suggests a new study published online October 31 in the  American Journal of Roentgenology.

The study retrospectively analysed chest CT scans obtained between 2007 and 2017 that had findings of septic PE associated with IV substance use disorder. Patients with history of IV substance use disorder, findings of septic PE on chest CT scans, and confirmation of infection were included in the study.

The reversed halo sign was reliably and frequently observed on the chest CT scans of patients with IV substance use disorder-related septic PE.

  • Around 60% of patients included in the study had reversed halo signs.
  • The mean number of unique reversed halo signs per patient was 2.1 ± 1.7 (46.7% of patients had more than one reversed halo sign).
  • Of 78 unique reversed halo signs, 73 (93.6%) were peripherally located and 40 (51.3%) were located at the lower lobe, 41 (52.6%) were pyramidal and 37 (47.4%) were round shaped, 70 (89.7%) had central low-attenuation areas and 27 (34.6%) had internal reticulations.

The study also identified characteristics of reversed halo sign presentation as potential features to differentiate septic PE from other causes of pulmonary infarct manifesting with reversed halo sign.

  • Twenty-nine (37.2%) of reversed halo signs cavitation, which was also observed more often in pyramid-shaped ones (70.8%), whereas consolidation occurred in 24 (30.8%) and more often in round-shaped ones (58.6%).

The authors concluded that septic PE should be included in the differential diagnosis of patients with IV substance use disorder presenting with reversed halo sign.

The reversed halo sign is characterised by a central ground-glass opacity surrounded by a more or less complete ring of consolidation on high-resolution CT (HRCT). It has also been described as the “atoll sign” because of its resemblance to a coral atoll. It was first described on HRCT as being specific for cryptogenic organising pneumonia (Br J Radiol. 2012 Sep;85(1017):1226-35).

(Source: AJR Am J Roentgenol. 2019 Oct 31:1-9)

 Dr KK Aggarwal

Padma Shri Awardee

President Confederation of Medical Associations in Asia and Oceania (CMAAO)

Group Editor-in-Chief IJCP Publications

President Heart Care Foundation of India

Past National President IMA

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