Over the past 10 years, the utility of MRI for detecting PNA has been studied more extensively in pediatric and immunocompromised patient populations; these studies demonstrated a similar favorable sensitivity of MRI for detecting PNA [15-20]. PET/CT Our literature search failed to identify any articles published within the past 10 years that justify the use of PET/CT in the initial workup of ARI in the immunocompetent patient. The usefulness of this imaging modality is not discussed in any of the clinical variants because of lack of evidence. CT Chest Our literature search failed to identify any data that suggest that CT serves any significant role in the initial imaging of immunocompetent patients with a low pretest probability of PNA. US Chest Many of the studies evaluating the potential of US to diagnose PNA in the ED are aimed at assessing the diagnostic accuracy of US for PNA using either CT or discharge diagnosis as the gold standard [8-11]. Many of these patients were sick enough to warrant CT or admission, representing a subset of patients with a relatively high pretest probability of PNA. The current literature does not suggest a routine role for initial imaging with US in a clinical variant with a low pretest probability of PNA. MRI Chest Our literature search failed to identify any data that suggest that MRI serves any significant role in the initial imaging of immunocompetent patients with a low pretest probability of PNA. Variant 2: Acute respiratory illnesses in immunocompetent patients with positive physical examination, abnormal vital signs, organic brain disease, or other risk factors. Initial imaging. Radiography Chest In a series of 300 patients with acute cough illness, Aagaard et al [29] found that a chest radiograph was not always obtained for patients with a high pretest probability of PNA; they infer that when the clinical probability of PNA exceeds a certain level, a negative radiograph would not alter treatment decisions.
Acute Respiratory Illness in Immunocompetent Patients. Over the past 10 years, the utility of MRI for detecting PNA has been studied more extensively in pediatric and immunocompromised patient populations; these studies demonstrated a similar favorable sensitivity of MRI for detecting PNA [15-20]. PET/CT Our literature search failed to identify any articles published within the past 10 years that justify the use of PET/CT in the initial workup of ARI in the immunocompetent patient. The usefulness of this imaging modality is not discussed in any of the clinical variants because of lack of evidence. CT Chest Our literature search failed to identify any data that suggest that CT serves any significant role in the initial imaging of immunocompetent patients with a low pretest probability of PNA. US Chest Many of the studies evaluating the potential of US to diagnose PNA in the ED are aimed at assessing the diagnostic accuracy of US for PNA using either CT or discharge diagnosis as the gold standard [8-11]. Many of these patients were sick enough to warrant CT or admission, representing a subset of patients with a relatively high pretest probability of PNA. The current literature does not suggest a routine role for initial imaging with US in a clinical variant with a low pretest probability of PNA. MRI Chest Our literature search failed to identify any data that suggest that MRI serves any significant role in the initial imaging of immunocompetent patients with a low pretest probability of PNA. Variant 2: Acute respiratory illnesses in immunocompetent patients with positive physical examination, abnormal vital signs, organic brain disease, or other risk factors. Initial imaging. Radiography Chest In a series of 300 patients with acute cough illness, Aagaard et al [29] found that a chest radiograph was not always obtained for patients with a high pretest probability of PNA; they infer that when the clinical probability of PNA exceeds a certain level, a negative radiograph would not alter treatment decisions.