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Reversed halo sign: high-resolution CT scan findings in 79 patients
Edson Marchiori1, Gláucia Zanetti1, Dante Luiz Escuissato2
1Federal University of Rio de Janeiro, Rio de Janeiro.
Insights
High-resolution CT (HRCT) scans reveal reversed halo sign (RHS) features. Nodular walls or nodules within the RHS halo strongly suggest granulomatous diseases, aiding differential diagnosis in chest imaging.
Area of Science:
- Radiology
- Pulmonology
- Medical Imaging
Background:
- The reversed halo sign (RHS) is an imaging finding on high-resolution CT (HRCT) scans.
- Identifying distinguishing features of RHS is crucial for diagnosing underlying conditions.
Purpose of the Study:
- To evaluate high-resolution CT (HRCT) scan findings in patients presenting with the reversed halo sign (RHS).
- To identify distinguishing imaging features that differentiate the various causes of RHS.
Main Methods:
- Retrospective review of HRCT scans from 79 patients with RHS by two experienced chest radiologists.
- Consensus determination of CT findings, including morphologic characteristics, lesion number, and associated features of RHS.
Main Results:
- Of 79 patients, 41 had infectious diseases and 38 had noninfectious diseases causing RHS.
- Smooth RHS walls were observed in 73.4% of patients, while nodular walls were seen in 26.6%.
- Multiple lesions were present in 50.6% of patients, and single lesions in 49.4%.
Conclusions:
- The presence of nodular walls or nodules within the halo of the RHS is highly suggestive of granulomatous diseases.
- HRCT findings can aid in differentiating infectious from noninfectious causes of RHS.
Background:
The purpose of this study was to evaluate the high-resolution CT (HRCT) scan findings of patients with the reversed halo sign (RHS) and to identify distinguishing features among the various causes.
Methods:
Two chest radiologists reviewed the HRCT scans of 79 patients with RHS and determined the CT scan findings by consensus. We studied the morphologic characteristics, number of lesions, and presence of features associated with RHS.
Results:
Forty-one patients presented with infectious diseases (paracoccidioidomycosis, TB, zygomycosis, invasive pulmonary aspergillosis, Pneumocystis jiroveci pneumonia, histoplasmosis, cryptococcosis), and 38 presented with noninfectious diseases (cryptogenic organizing pneumonia, pulmonary embolism, sarcoidosis, edema, lepidic predominant adenocarcinoma [formerly bronchiolo-alveolar carcinoma], granulomatosis with polyangiitis [Wegener]). The RHS walls were smooth in 58 patients (73.4%) and nodular in 21 patients (26.6%). Lesions were multiple in 40 patients (50.6%) and single in 39 patients (49.4%).
Conclusion:
The presence of nodular walls or nodules inside the halo of the RHS is highly suggestive of granulomatous diseases.
