Imaging Infection

Abstract

Thoracic imaging is widely used to detect lower respiratory tract infections, identify their complications, and aid in differentiating infectious from noninfectious thoracic disease. Less commonly, the combination of imaging findings and a clinical setting can favor infection with a specific organism. This confluence can occur in cases of bronchiectatic nontuberculous mycobacterial infections in immune-competent hosts, invasive fungal disease among neutropenic patients, Pneumocystis jiroveci pneumonia in patients with AIDS, and in cytomegalovirus infections in patients with recent hematopoietic cell transplantation. These specific diagnoses often depend on computed tomography scanning rather than chest radiography alone.

Imaging Pulmonary Infection: Classic Signs and Patterns

“…In a patient with pneumonia, the CT detection of inhomogeneous enhancement and cavitation suggests the presence of necrotizing infection [25,26]. Pulmonary necrosis may become evident as hypoenhancing geographic areas of low lung attenuation that may be difficult to differentiate from adjacent pleural fluid [25] (Fig. 7).…”

Severe infections in critically ill solid organ transplant recipients

“…If not treated promptly, they progress to acute respiratory failure. Chest X-ray can be sufficient to diagnose community-acquired pneumonia, but it is less useful for hospital-acquired or ventilator-associated pneumonia because of the common presence of underlying atelectasis, oedema, or effusions [17,33,34]. Computer tomography (CT) is more useful in these settings, although differentiating hospital-acquired or ventilator-associated pneumonia from other noninfectious causes may be difficult.…”

“…CT scans are useful to detect early changes consistent with mediastinitis or pleural disease after heart or lung transplantation [25,35,36]. CT scan has high sensitivity for detecting infiltrates, multilobar involvement or cavitary lesions [37], lymphadenopathy, lung abscesses, necrosis or empyema [34]. Findings suggestive of invasive fungal infections (Aspergillus, Cryptococcus), Mycobacteria and Nocardia can be appreciated with CT scans [37,38]; the halo sign (invasive aspergillosis or mucormycosis) is more commonly seen after haematopoietic stem-cell transplantation than after SOT [39].…”

“…Findings suggestive of invasive fungal infections (Aspergillus, Cryptococcus), Mycobacteria and Nocardia can be appreciated with CT scans [37,38]; the halo sign (invasive aspergillosis or mucormycosis) is more commonly seen after haematopoietic stem-cell transplantation than after SOT [39]. CMV pneumonia may present with bilateral infiltrates, ground-glass opacities, consolidations or nodular lesions [34]. PJP may present with bilateral ground-glass opacities, more upper lobes involvement and septal thickening [40].…”

Multiple nodular lesions following Pneumocystis pneumonia in a non‐HIV immunocompromised patient

“…Although ground glass opacity is observed on CT in both diseases, variously sized multiple nodules are observed more frequently in CMV than in PCP . Aspergillus , Cryptococcus , and Nocardia infection are included in the differential diagnosis of pulmonary nodules in a non‐HIV immunocompromised patient; however, the nodules in CMV pneumonia are smaller (<1 cm) on CT . CMV pneumonia should be considered in cases showing not only simultaneous infection with PCP but also deterioration after initiating PCP treatment; small multiple nodular lesions are useful findings for confirming the diagnosis.…”