In another study in patients with pulmonary tuberculosis, 11% of HIV-positive patients had normal chest radiographs [7]. Similarly, up to one-third of patients infected with Pneumocystis jirovecii may have normal chest radiographs [8]. In addition, because of its superior spatial resolution and cross-sectional display of findings, CT provides enhanced characterization of pulmonary parenchymal abnormalities, which is often helpful in formulating a differential diagnosis. MRI Chest CT is preferable to MRI in immunocompromised patients with ARI who have normal, equivocal, or nonspecific chest radiographs. CT remains superior to MRI in the detection and characterization of pulmonary parenchymal infection [9,10]. However, MRI can be considered as an alternative imaging modality, albeit less sensitive. 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 normal, equivocal, or nonspecific chest radiographs. Therefore, FDG-PET/CT should be rarely utilized in this clinical scenario. Furthermore, many pulmonary infections typically have high FDG uptake and, thus, may be mistaken for malignancy [13]. Variant 3: Acute respiratory illness in immunocompromised patients. Abnormal chest radiograph, multiple, diffuse, or confluent opacities. Next imaging study. CT Chest Further investigation with CT is warranted in immunocompromised patients with ARI who have chest radiographs showing multiple, diffuse, or confluent opacities. In this patient population, multiple or diffuse opacities or nodules have a higher probability of representing an atypical opportunistic infection rather than community-acquired bacterial pneumonia [4,14].
Acute Respiratory Illness in Immunocompromised Patients. In another study in patients with pulmonary tuberculosis, 11% of HIV-positive patients had normal chest radiographs [7]. Similarly, up to one-third of patients infected with Pneumocystis jirovecii may have normal chest radiographs [8]. In addition, because of its superior spatial resolution and cross-sectional display of findings, CT provides enhanced characterization of pulmonary parenchymal abnormalities, which is often helpful in formulating a differential diagnosis. MRI Chest CT is preferable to MRI in immunocompromised patients with ARI who have normal, equivocal, or nonspecific chest radiographs. CT remains superior to MRI in the detection and characterization of pulmonary parenchymal infection [9,10]. However, MRI can be considered as an alternative imaging modality, albeit less sensitive. 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 normal, equivocal, or nonspecific chest radiographs. Therefore, FDG-PET/CT should be rarely utilized in this clinical scenario. Furthermore, many pulmonary infections typically have high FDG uptake and, thus, may be mistaken for malignancy [13]. Variant 3: Acute respiratory illness in immunocompromised patients. Abnormal chest radiograph, multiple, diffuse, or confluent opacities. Next imaging study. CT Chest Further investigation with CT is warranted in immunocompromised patients with ARI who have chest radiographs showing multiple, diffuse, or confluent opacities. In this patient population, multiple or diffuse opacities or nodules have a higher probability of representing an atypical opportunistic infection rather than community-acquired bacterial pneumonia [4,14].