RC 104 - Pneumonia
1. To review the role of imaging in infectious lung diseases.
2. To become confident in recognising typical patterns.
Pneumonia is a major health care and economic problem because of high morbidity and mortality rate, and due to direct and indirect costs of its management. The most common cause is community-acquired pneumonia, caused by common bacteria like S. Pneumonia as well as different viral agents. Tuberculosis is one of the most important respiratory infections in developing countries and in immune-compromised patients with AIDS everywhere. Tuberculosis pneumonia can easily mimic bacterial CAP and other pulmonary infections. Viral and mycotic infections represent a common course of febrile neutropenia in immune-compromised patients under aggressive therapy. In most of all these patients, a diagnosis is made on the basis of a combination of clinical, radiographic, and laboratory findings. High-resolution CT is usually performed in patients with nonspecific clinical and radiologic findings and in patients with progression of disease despite therapy. A large number of acute and chronic infectious and noninfectious diseases may also result in parenchymal lung disease in both immune-competent and immune-compromised patients. Thin section CT is also performed in patients with noninfectious causes of acute parenchymal lung disease such as organizing pneumonia, acute interstitial pneumonia, hypersensitivity pneumonitis, acute eosinophilic pneumonia, pulmonary oedema and haemorrhage. These diseases often have clinical and functional features similar to one another but obviously requiring different treatment. Therefore, the differential diagnosis of these entities is important in daily clinical practice.
1. To appreciate the role of imaging in the management of community-acquired pneumonia.
2. To consolidate knowledge of how to discriminate from noninfectious diseases.
Community-acquired pneumonia (CAP) refers to pneumonia acquired outside of hospitals or extended-care facilities and is one of the most common infectious diseases. CAP is an important cause of mortality and morbidity worldwide. According to the IDSA/ATS/AAFP guidelines, a chest radiograph is required for the routine evaluation of patients with suspected CAP to exclude conditions that mimic CAP (e.g., acute bronchitis) and to confirm the presence of an infiltrate compatible with the presentation of CAP. Although chest radiography findings usually do not allow identifying the causative organism, they may be helpful in narrowing down the differential diagnosis, prognosis, and detection of associated conditions. Serial chest radiography can be performed to observe the progression of CAP. CT scanning is increasingly used in clinical practice. Performing CT should be considered if any of the abnormalities at presentation or at follow-up are not consistent with the diagnosis of pneumonia, if concomitant disease is suspected such as an underlying bronchogenic carcinoma, for the confirmation of pleural effusion, and for the detection of pulmonary complications. The aim of the presentation is to provide an overview of the imaging findings of the most common aetiologic organisms in patients with CAP. In addition, imaging findings that may help in the differentiation between pneumonia and other common non-infectious causes of abnormal chest radiographs in patients with suspected CAP will be discussed.
1. To appreciate typical and atypical tuberculosis manifestations on imaging.
2. To differentiate between acute and chronic tuberculosis infection.
Pulmonary tuberculosis (TB) remains a common worldwide infection that produces high mortality and morbidity, especially in developing countries. In 2013, an estimated 9.0 million (360 000 of whom were HIV-positive) people developed TB and 1.5 million died from the disease. Chest radiographs play a major role in the screening, diagnosis and response to treatment of patients with TB. However, the radiographs may be normal or show only mild or nonspecific findings in patients with active disease. We will review the chest radiograph findings of TB, which vary widely in function of several host factors, age, prior exposure to TB, and underlying immune status. CT is useful, in detecting TB incidentally, in resolving cases with inconclusive findings on chest radiographs and in assessing disease activity. Cavities, centrilobular nodules and tree-in-bud appearance are the most common CT findings of active pulmonary tuberculosis. We will discuss the classic, and some not-so-classic, signs that should suggest the diagnosis of TB.
1. To learn the patterns of fungal lung infection depending on the type of immune depression.
2. To become familiar with CT signs suggesting angioinvasive fungal infection.
The radiological characterisation of infiltrates gives a first and rapid hint to differentiate between different types of infectious (e.g. typical bacterial, atypical bacterial, fungal) and non-infectious aetiologies. Follow-up investigations need careful interpretation according to disease, recovery, concomitant treatment and eventually vessel erosion requiring contrast-enhanced angio-CT. Due to a high incidence of fungal infiltrates in immunocompromised hosts, interpretation of the follow-up of an infiltrate must use further parameters besides the lesion size.