From the Guidelines
Radiologic findings in aspergillosis are characterized by the presence of nodules, cavities, and infiltrates on imaging studies, with a characteristic "fungus ball" or aspergilloma appearing as a round mass within a pre-existing lung cavity, often with a crescent-shaped air space called the "air crescent sign". In pulmonary aspergillosis, chest X-rays and CT scans may show these characteristic findings, which are essential for diagnosis and management 1. The imaging features of chronic pulmonary aspergillosis (CPA) result from a combination of underlying lung disorders and changes secondary to Aspergillus infection, reflecting the chronic inflammatory and immune response to Aspergillus spp.
Some key radiologic findings in aspergillosis include:
- Nodules and cavities, which are common in pulmonary aspergillosis
- Fungus ball or aspergilloma, which appears as a round mass within a pre-existing lung cavity
- Air crescent sign, which is a crescent-shaped air space surrounding the fungus ball
- Pleural thickening and marked parenchymal destruction and/or fibrosis, which are characteristic of CPA
- Enlargement of bronchial or non-bronchial systemic arteries and pseudo-aneurysms, which may lead to fatal haemoptysis
According to the European Respiratory Journal study 1, the distinctive hallmarks of CPA are new and/or expanding cavities of variable wall thickness in the setting of chronic lung disease with or without intracavitary fungal ball formation, often with pleural thickening and marked parenchymal destruction and/or fibrosis. The 2018 Clinical Microbiology and Infection study 1 also recommends chest computed tomography and bronchoscopy with bronchoalveolar lavage (BAL) in patients with suspicion of pulmonary invasive aspergillosis (IA).
The diagnosis and management of aspergillosis should be guided by these radiologic findings, as well as other diagnostic tests such as direct microscopy, histopathology, and culture, and antifungal therapy with agents like voriconazole or amphotericin B should be initiated promptly. The choice of antifungal agent and treatment duration should be based on clinical improvement, degree of immunosuppression, and response on imaging, as recommended by the 2018 Clinical Microbiology and Infection study 1.
From the Research
Radiologic Findings in Aspergillosis
- The radiologic findings in aspergillosis can vary depending on the type of aspergillosis and the underlying condition of the patient 2, 3, 4.
- In saprophytic aspergillosis (aspergilloma), computed tomography (CT) typically shows a mass with soft-tissue attenuation within a lung cavity, often associated with thickening of the wall and adjacent pleura, and an "air crescent" sign 2.
- Allergic bronchopulmonary aspergillosis (ABPA) is characterized by mucoid impaction and bronchiectasis involving predominantly the segmental and subsegmental bronchi of the upper lobes on CT 2, 5.
- Invasive aspergillosis can manifest as nodules surrounded by a halo of ground-glass attenuation ("halo sign") or pleura-based, wedge-shaped areas of consolidation on CT 2, 3.
- CT findings in obstructing bronchopulmonary aspergillosis include bilateral bronchial and bronchiolar dilatation, large mucoid impactions, and diffuse lower lobe consolidation caused by postobstructive atelectasis 2.
- Bronchiolitis due to aspergillosis can appear as centrilobular nodules and branching linear or nodular areas of increased attenuation ("tree-in-bud" pattern) on CT 2.
CT Findings
- CT is currently the best imaging modality for the assessment of pulmonary parenchymal disease in aspergillosis 4.
- CT had a higher sensitivity for multiplicity of lesions and cavitation compared with the plain chest film in invasive pulmonary aspergillosis (IPA) 3.
- The CT findings in aspergillosis can be nonspecific, but in the appropriate clinical setting, familiarity with the CT findings may suggest or even help establish the diagnosis 2, 4.