Newer pulse sequences on 3T scanners may further enhance the diagnostic performance of MRI [11,34,35]. Therefore, as technology continues to improve, MRI represents a promising imaging modality for the workup of immunocompromised patients with abnormal chest radiographs. Moreover, once a diagnosis of infection has been established, MRI can be used as a reasonable alternative to CT for follow-up of parenchymal disease [10-12]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature regarding the use of FDG-PET/CT in the evaluation of immunocompromised patients with ARI who have chest radiographs showing multiple, diffuse, or confluent opacities. Therefore, FDG- PET/CT should be rarely utilized in this clinical scenario. Furthermore, many pulmonary infections typically cause high FDG uptake and, thus, may be mistaken for malignancy [13]. Image-Guided Transthoracic Needle Biopsy Image-guided transthoracic needle biopsy may play a role in the identification of the specific organism(s) producing pulmonary parenchymal abnormalities in certain clinical scenarios of immunocompromised patients with ARI. Though the diagnostic yield of transthoracic biopsy in detecting infections is significantly less than in detecting malignancies, the underlying pathogen is identified a significant minority of the time, which allows for prompt and appropriate treatment of the infection in these vulnerable patients [36,37]. Transthoracic biopsy demonstrates the greatest value in the diagnosis of fungal infections, even in the presence of normal sputum and blood cultures [36,38,39]. Even if chest radiography reveals the parenchymal opacities, CT should typically still be performed prior to contemplating transthoracic needle biopsy, as certain lesions may be more amenable to bronchoscopic biopsy if they are in close proximity to the airways.
Acute Respiratory Illness in Immunocompromised Patients. Newer pulse sequences on 3T scanners may further enhance the diagnostic performance of MRI [11,34,35]. Therefore, as technology continues to improve, MRI represents a promising imaging modality for the workup of immunocompromised patients with abnormal chest radiographs. Moreover, once a diagnosis of infection has been established, MRI can be used as a reasonable alternative to CT for follow-up of parenchymal disease [10-12]. FDG-PET/CT Skull Base to Mid-Thigh There is no relevant literature regarding the use of FDG-PET/CT in the evaluation of immunocompromised patients with ARI who have chest radiographs showing multiple, diffuse, or confluent opacities. Therefore, FDG- PET/CT should be rarely utilized in this clinical scenario. Furthermore, many pulmonary infections typically cause high FDG uptake and, thus, may be mistaken for malignancy [13]. Image-Guided Transthoracic Needle Biopsy Image-guided transthoracic needle biopsy may play a role in the identification of the specific organism(s) producing pulmonary parenchymal abnormalities in certain clinical scenarios of immunocompromised patients with ARI. Though the diagnostic yield of transthoracic biopsy in detecting infections is significantly less than in detecting malignancies, the underlying pathogen is identified a significant minority of the time, which allows for prompt and appropriate treatment of the infection in these vulnerable patients [36,37]. Transthoracic biopsy demonstrates the greatest value in the diagnosis of fungal infections, even in the presence of normal sputum and blood cultures [36,38,39]. Even if chest radiography reveals the parenchymal opacities, CT should typically still be performed prior to contemplating transthoracic needle biopsy, as certain lesions may be more amenable to bronchoscopic biopsy if they are in close proximity to the airways.