High-resolution computed tomography (HRCT) of lung infections in non-AIDS immunocompromised patients

Abstract

Non-AIDS immunocompromised patients are susceptible to infections by a wide range of organisms. In the past several decades, advances in the treatment of cancer, organ transplantation, and immunosuppressive therapy have resulted in large numbers of patients who develop abnormalities in their immune system. Moreover, mildly impaired host immunity as it occurs in chronic debilitating illness, diabetes mellitus, malnutrition, alcoholism, advanced age, prolonged corticosteroid administration, and chronic obstructive lung disease have also been regarded as predisposing factors of pulmonary infections. Imaging plays a crucial role in the detection and management of patients with pulmonary infectious diseases. When pulmonary infection is suspected, knowledge of the varied radiographic manifestations will narrow the differential diagnosis, helping to direct additional diagnostic measures and serving as an ideal tool for follow-up examinations. Combination of pattern recognition with knowledge of the clinical setting is the best approach to pulmonary infection occurring in the immunocompromised patients.

ACR Appropriateness Criteria® Acute Respiratory Illness in Immunocompromised Patients

“…Although not recommended for the initial imaging evaluation of patients with ARI, the use of CT has been described in several scenarios with respect to the immunocompromised host: to evaluate patients who are clinically symptomatic for ARI but who have equivocal or normal chest radiographic findings, to better characterize abnormal but nonspecific chest radiograph findings, and to provide essential information for determining the appropriate method and site of lung biopsy. 6 Because the appearance and distribution of airspace abnormalities are better characterized with the improved resolution provided by CT, certain diseases such as Pneumocystis jirovecii pneumonia (PJP), invasive pulmonary aspergillosis, and cytomegalovirus can be identified on CT with a higher degree of confidence than they can on radiography. [7][8][9][10][11] Recognizing the CT patterns associated with these infections allows for the critical initiation of early empiric therapy, often based on a presumptive radiologic diagnosis, all the while waiting for more definitive microbiological data, which may not be available for days or weeks.…”

“…4 In this setting, chest CT has been shown to offer a distinct advantage in sensitivity for detecting subtle parenchymal abnormalities. 6,13,14 With the improved resolution of CT, even subtle parenchymal abnormalities that would escape detection on the chest radiograph become manifest. The appearance and distribution of lung abnormalities on CT, coupled with information of the patient's clinical presentation, are often quite helpful in formulating a differential diagnosis.…”

“…2,6 The well-recognized patterns of disease that CT is able to detect, taken together with appropriate clinical and laboratory data, go a long way in piecing together the diagnostic puzzle.…”

Performance of magnetic resonance imaging in pulmonary fungal disease compared to high‐resolution computed tomography

“…Lung mycosis is usually self‐limited, but some patients develop chronic infection. The main clinical issue related to this infection is the lack of criteria to define a healed status, which, in some cases, can lead to an unnecessary follow‐up for many years with chest computed tomography (CT), creating a concern related to high radiation exposure . High‐resolution computed tomography (HRCT) is the gold standard for the diagnosis and follow‐up of lung mycosis .…”

Respiratory multiplex polymerase chain reaction: An important diagnostic tool in immunocompromised patients

“…The important causes of immunosuppression are solid organ transplantation, hematopoietic stem cells transplantation, cancer therapy, HIV infection, autoimmune diseases, primary immunodeficiencies, long-term steroid use, diabetes mellitus, and chronic debilitating illness. [12] The immunocompromised patients are more prone to various infections as compared to the immunocompetent ones. The organisms which are of little native virulence in the immunocompetent, can cause life-threatening complications in immunocompromised.…”