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The halo sign: HRCT findings in 85 patients
Giordano Rafael Tronco Alves1, Edson Marchiori1, Klaus Irion2
1. Programa de Pós-Graduação em Medicina (Radiologia), Universidade Federal do Rio de Janeiro, Rio de Janeiro (RJ) Brasil.
Insights
The halo sign on chest CT scans differs between immunocompetent and immunosuppressed patients. Immunosuppressed patients more frequently show multiple, randomly distributed lesions with thicker halos, often indicating aspergillosis.
Area of Science:
- Radiology
- Pulmonary Medicine
- Infectious Diseases
Background:
- The halo sign, characterized by ground-glass opacity around pulmonary lesions on CT scans, has distinct features.
- Understanding these differences is crucial for accurate diagnosis in diverse patient populations.
Purpose of the Study:
- To compare halo sign features in immunocompetent versus immunosuppressed patients.
- To identify specific features of the halo sign with the highest diagnostic value.
Main Methods:
- Retrospective analysis of 85 patients' chest CT scans (2011-2015).
- Patients classified by immune status (immunocompetent vs. immunosuppressed).
- Radiologists assessed lesion number, distribution, size, contour, and halo thickness.
Main Results:
- Immunosuppressed patients (n=32) more often had aspergillosis (78%), while immunocompetent patients (n=53) predominantly had primary neoplasms (64%).
- Multiple, randomly distributed lesions were more common in immunosuppressed individuals (p < 0.001).
- Thicker halos were observed in immunosuppressed patients (p < 0.05).
Conclusions:
- Etiologies of the halo sign vary significantly between immunocompetent and immunosuppressed groups.
- While thicker halos suggest infectious diseases, lesion number and distribution are also key diagnostic indicators.
- Integrating these features aids in evaluating patients with the halo sign.
Objective::
The halo sign consists of an area of ground-glass opacity surrounding pulmonary lesions on chest CT scans. We compared immunocompetent and immunosuppressed patients in terms of halo sign features and sought to identify those of greatest diagnostic value.
Methods::
This was a retrospective study of CT scans performed at any of seven centers between January of 2011 and May of 2015. Patients were classified according to their immune status. Two thoracic radiologists reviewed the scans in order to determine the number of lesions, as well as their distribution, size, and contour, together with halo thickness and any other associated findings.
Results::
Of the 85 patients evaluated, 53 were immunocompetent and 32 were immunosuppressed. Of the 53 immunocompetent patients, 34 (64%) were diagnosed with primary neoplasm. Of the 32 immunosuppressed patients, 25 (78%) were diagnosed with aspergillosis. Multiple and randomly distributed lesions were more common in the immunosuppressed patients than in the immunocompetent patients (p < 0.001 for both). Halo thickness was found to be greater in the immunosuppressed patients (p < 0.05).
Conclusions::
Etiologies of the halo sign differ markedly between immunocompetent and immunosuppressed patients. Although thicker halos are more likely to occur in patients with infectious diseases, the number and distribution of lesions should also be taken into account when evaluating patients presenting with the halo sign.
Objetivo::
O sinal do halo consiste em uma área de opacidade em vidro fosco ao redor de lesões pulmonares em imagens de TC de tórax. Pacientes imunocompetentes e imunodeprimidos foram comparados quanto a características do sinal do halo a fim de identificar as de maior valor diagnóstico.
MéTodos::
Estudo retrospectivo de tomografias realizadas em sete centros entre janeiro de 2011 e maio de 2015. Os pacientes foram classificados de acordo com seu estado imunológico. Dois radiologistas torácicos analisaram os exames a fim de determinar o número de lesões e sua distribuição, tamanho e contorno, bem como a espessura do halo e quaisquer outros achados associados.
Resultados::
Dos 85 pacientes avaliados, 53 eram imunocompetentes e 32 eram imunodeprimidos. Dos 53 pacientes imunocompetentes, 34 (64%) receberam diagnóstico de neoplasia primária. Dos 32 pacientes imunodeprimidos, 25 (78%) receberam diagnóstico de aspergilose. Lesões múltiplas e distribuídas aleatoriamente foram mais comuns nos imunodeprimidos do que nos imunocompetentes (p < 0,001 para ambas). A espessura do halo foi maior nos imunodeprimidos (p < 0,05).
ConclusõEs::
As etiologias do sinal do halo em pacientes imunocompetentes são bastante diferentes das observadas em pacientes imunodeprimidos. Embora halos mais espessos ocorram mais provavelmente em pacientes com doenças infecciosas, o número e a distribuição das lesões também devem ser levados em conta na avaliação de pacientes que apresentem o sinal do halo.
