ECR: CT can help detect under-diagnosed pulmonary infections
Nontuberculous mycobacterial (NTM) pulmonary infections, the rising number of immunocompromised patients likely to develop an infection and changes in AIDS-related thoracic complications are now challenging the medical system, according to a series of presentations at the 2009 meeting of the European College of Radiology (ECR) in Vienna, Austria, this week. By learning how to recognize early signs using CT, radiology can help make the most appropriate diagnosis.
NTM pulmonary infections are a group of under-diagnosed, yet very common conditions, which have very subtle clinical manifestations, such as a light chronic cough. Women over 50 who have a bronchial disease in the middle lobe and lingula are particularly at risk. Typically, NTM pulmonary infections present on high-resolution CT (HRCT) scans with small areas of cavitation in the lungs or tree-in-buds in a patient with a bronchial disease, according to researchers. Nodular opacities or cavitations in the upper lobes in patients with a chronic obstructive pulmonary disease (COPD) or bronchitis are also quite representative.
It is crucial to be aware of these infections, which are greatly under-diagnosed, partly because of the lack of information on their incidence, according to Professor Tomás Franquet, MD, from Barcelona, who chaired the session. Unlike tuberculosis, hospitals and practices do not need to declare a case of NTM pulmonary infection to sanitary authorities, and the radiologist is often the first to suspect this possibility.
"Radiologists should bear this entity in mind even more so," Franquet said. "The incidence is hard to know, but one thing is for certain: NTM pulmonary infections occur much more often than we clinicians diagnose them."
Immunocompromised patients more likely to develop an infection, the researchers reported. Their number has been on the rise for the past ten years; the AIDS epidemics and the increase in transplant patients, as well as people receiving chronic treatment with steroids or anti-neoplastic drugs have significantly augmented the population at risk.
Immunocompromised patients can be divided into two groups: the moderately or mildly immunocompromised, comprising smokers, diabetics and those with chronic pulmonary diseases, bronchitis or COPD; and the totally immunocompromised, such as AIDS or transplant patients. These groups are particularly at risk of contracting community-acquired pneumonia (CAP), the most common infection process globally. In addition, people suffering from a kind of immunosuppression, such as asthma, or under a long term steroid treatment, are also more likely than others to develop CAP.
As most HIV patients are now treated with the highly active anti-viral retroactive therapy, AIDS-related thoracic complications have also changed, according to reserachers. Instead of the fungal infection pneumocystis pneumonia, now CAP, a pneumococcal pneumonia, has become the most frequent cause of pulmonary infection in AIDS patients.
Currently, the imaging patterns of pulmonary infection have also changed in immunocompetent individuals. "A pneumococcal infection may present with cavitation, pleural effusion or as multiple pulmonary nodules. These imaging patterns are different to lobar consolidation, a classical form of presentation ten years ago," Franquet said.
The researchers concluded that many of these infections can be diagnosed with CT exams. If chest x-ray is the first radiological step to take for a patient with a suspected pulmonary infection, CT may show subtle parenchymal abnormalities that are not detectable with plain film.
"CT is highly recommended in imaging immunocompromised patients because the infection is much more aggressive in this group. Several reports have even shown that CT may demonstrate abnormal findings one week earlier than the same on plain film in neutropenic patients; a sizeable gain in time," according to the researchers.
NTM pulmonary infections are a group of under-diagnosed, yet very common conditions, which have very subtle clinical manifestations, such as a light chronic cough. Women over 50 who have a bronchial disease in the middle lobe and lingula are particularly at risk. Typically, NTM pulmonary infections present on high-resolution CT (HRCT) scans with small areas of cavitation in the lungs or tree-in-buds in a patient with a bronchial disease, according to researchers. Nodular opacities or cavitations in the upper lobes in patients with a chronic obstructive pulmonary disease (COPD) or bronchitis are also quite representative.
It is crucial to be aware of these infections, which are greatly under-diagnosed, partly because of the lack of information on their incidence, according to Professor Tomás Franquet, MD, from Barcelona, who chaired the session. Unlike tuberculosis, hospitals and practices do not need to declare a case of NTM pulmonary infection to sanitary authorities, and the radiologist is often the first to suspect this possibility.
"Radiologists should bear this entity in mind even more so," Franquet said. "The incidence is hard to know, but one thing is for certain: NTM pulmonary infections occur much more often than we clinicians diagnose them."
Immunocompromised patients more likely to develop an infection, the researchers reported. Their number has been on the rise for the past ten years; the AIDS epidemics and the increase in transplant patients, as well as people receiving chronic treatment with steroids or anti-neoplastic drugs have significantly augmented the population at risk.
Immunocompromised patients can be divided into two groups: the moderately or mildly immunocompromised, comprising smokers, diabetics and those with chronic pulmonary diseases, bronchitis or COPD; and the totally immunocompromised, such as AIDS or transplant patients. These groups are particularly at risk of contracting community-acquired pneumonia (CAP), the most common infection process globally. In addition, people suffering from a kind of immunosuppression, such as asthma, or under a long term steroid treatment, are also more likely than others to develop CAP.
As most HIV patients are now treated with the highly active anti-viral retroactive therapy, AIDS-related thoracic complications have also changed, according to reserachers. Instead of the fungal infection pneumocystis pneumonia, now CAP, a pneumococcal pneumonia, has become the most frequent cause of pulmonary infection in AIDS patients.
Currently, the imaging patterns of pulmonary infection have also changed in immunocompetent individuals. "A pneumococcal infection may present with cavitation, pleural effusion or as multiple pulmonary nodules. These imaging patterns are different to lobar consolidation, a classical form of presentation ten years ago," Franquet said.
The researchers concluded that many of these infections can be diagnosed with CT exams. If chest x-ray is the first radiological step to take for a patient with a suspected pulmonary infection, CT may show subtle parenchymal abnormalities that are not detectable with plain film.
"CT is highly recommended in imaging immunocompromised patients because the infection is much more aggressive in this group. Several reports have even shown that CT may demonstrate abnormal findings one week earlier than the same on plain film in neutropenic patients; a sizeable gain in time," according to the researchers.