Update on lung disease in AIDS

Computed tomography for the diagnosis of infectious diseases of the chest

BACKGROUND

Pulmonary infection is a common reason for imaging of the lung in immunocompetent and immunosuppressed patients. Findings on chest radiography are nonspecific and encompass poor sensitivity. The role of computed tomography (CT) has been evolving in the diagnosis of lung infections.

OBJECTIVE

This paper reviews recent developments in the efficacy and utility of CT in the diagnosis of suspected pulmonary infections in a variety of patient populations.

METHODS

Recent published literature was reviewed to prepare this treatise on the role of CT.

CONCLUSION

Knowledge and skills at pattern recognition are crucial for the CT interpretation in lung infections. Computed tomography scan is increasingly used to increase the sensitivity of the radiologic diagnosis of thoracic infections. The greatest value of CT is when the radiograph is normal, findings are equivocal, and to differentiate infection from non-infectious disorders.

Radiographic features of paediatric pneumocystis pneumonia -- a historical perspective

AIM

To determine differences between the plain radiographic features of paediatric pneumocystis pneumonia (PCP) recorded before the emergence of human immunodeficiency virus (HIV) in 1982 and those documented in the HIV era. To establish differences in the radiographic features of PCP documented in HIV-infected children in developed and developing countries.

METHOD

A Medline search of articles was conducted from 1950 to 2006, using the terms "pneumocystis pneumonia in children" and "chest radiographic features" or "bilateral opacification" or "lobar consolidation" or "asymmetrical opacification" or "pneumatocoeles" or "cavities" or "pneumothorax" or "pneumomediastinum" or "pleural effusion" or "mediastinal adenopathy" or "nodules" or "normal chest radiography". Appropriate articles were retrieved, radiological data extracted, reference lists examined and hand searches of referenced articles conducted.

RESULTS

Diffuse bilateral "ground-glass" or alveolar pulmonary opacification, which may show some asymmetry, has been consistently documented as the commonest radiographic finding in childhood PCP throughout the period under review. The less common radiological features of PCP in children are similar to those in adults. In developed countries, PCP-related pulmonary air cysts have been reported at an earlier age in HIV-infected children, compared with uninfected children. PCP-related air cysts, pneumothorax, and pneumomediastinum have been reported in children in developed but not in developing countries.

CONCLUSION

The radiological features of paediatric PCP documented before the HIV epidemic are similar to those recorded in the HIV era. Further study of the determinants of the uncommon radiographic features in children is warranted.

Alterações radiográficas em pacientes com a co-infecção vírus da imunodeficiência humana/tuberculose: relação com a contagem de células TCD4+

OBJETIVO: Correlacionar os padrões radiológicos com a contagem de células TCD4+ em pacientes co-infectados por tuberculose e vírus da imunodeficiência humana. MÉTODO: Foram avaliados os pacientes admitidos no Hospital Nereu Ramos, Florianópolis (SC), co-infectados por tuberculose e vírus da imunodeficiência humana, no período de janeiro de 2000 a dezembro de 2003. RESULTADOS: Foram incluídos no estudo 87 pacientes, com média de idade de 34 ± 8 anos, sendo 6,8% não caucasianos. A média de linfócitos TCD4+ foi de 220,2 células/mm³ e a mediana foi de 144 células/mm³, sendo que 56,4% dos pacientes possuíam menos de 200 células/mm³. Os padrões radiográficos isolados foram relacionados com a contagem de células TCD4+. O padrão de consolidação alveolar estava presente em 50,6% dos casos (56,8% TCD4+ < 200); o intersticial em 32,2% (53,6% TCD4+ < 200); derrame pleural em 24,1% (47,6% TCD4+ < 200); cavitação em 24,1% (57,1% TCD4+ < 200); linfonodomegalia mediastinal e/ou hilar em 11,5% (90% TCD4+ < 200); e sem alterações radiológicas em 11,5% deles (60% TCD4+ < 200). A média dos linfócitos para cada padrão radiológico foi de 235,2/mm³ (consolidação alveolar); 208,8/mm³ (intersticial); 243,3/mm³ (derrame pleural); 265/mm³ (cavitação); 115,1/mm³ (linfonodomegalia mediastinal e/ou hilar) (p < 0,05); e 205,5/mm³ (sem alteração radiológica). A linfonodomegalia mediastinal e/ou hilar foi o único padrão que se correlacionou de forma estatisticamente significativa com o grau de imunidade celular. CONCLUSÃO: Com exceção da linfonodomegalia mediastinal e/ou hilar, as alterações radiológicas distribuíram-se aleatoriamente em relação à contagem de células TCD4+.

Diagnosis of IPA in HIV: the role of the chest X-ray and radiologist

The role of clinical information and chest film for the discrimination between invasive pulmonary aspergillosis (IPA) and its differential diagnoses in human immunodeficiency virus (HIV) infection was studied. The diagnostic performance of clinical information and chest film alone and in combination was studied for eight internists and eight radiologists with regular exposure to IPA patients. The multicenter case sample consisted of 25 patients with proven IPA and 25 with other pulmonary diseases typical for HIV. The cases were presented on a CD-ROM. Receiver operating characteristics (ROC) methodology was employed. With clinical information alone, internists achieved the highest diagnostic performance (area under curve/AUC=0.84). Viewing the chest films did not contribute to their performance (AUC=0.80, P=0.26). The radiologist's performance on the basis of viewing the chest film (AUC=0.75) increased significantly ( P=0.012) when clinical information (AUC=0.83) was supplied. IPA cases with characteristic radiological appearance were correctly identified in 90% with chest film. For radiologists with regular exposure to HIV patients, chest films hold relevant information and contribute to the determination in cases with characteristic radiological appearance. Overall and especially in cases with less characteristic radiological appearance, they have significant profit from full access to the clinical data. For internists with regular exposure to HIV patients, chest films do not provide information essential for the verification or differentiation of potential IPA.

Imaging features of bacterial respiratory infections in AIDS

PURPOSE OF REVIEW

Although an emphasis has historically been placed on nonbacterial, opportunistic respiratory infections in HIV-infected individuals, it is increasingly important for clinicians to be familiar with the spectrum of bacterial respiratory infections that may occur in this population.

RECENT FINDINGS

Bacterial pneumonia and acute bronchitis are currently the most common causes of respiratory disease in HIV-infected individuals in developed countries. Moreover, these infections are frequently the first clinical manifestation of HIV infection. Among patients with sustained CD4 cell count >200 cells/microL, the discontinuation of Pneumocystis carinii pneumonia prophylaxis is not associated with an increased risk of bacterial pneumonia. The most common radiographic pattern of bacterial pneumonia is focal consolidation, which typically presents in either a segmental or lobar distribution. In cases in which the chest radiograph is inconclusive, high-resolution chest CT has a very high accuracy for detecting pyogenic small airways disease and for distinguishing between P. carinii pneumonia and other lung infections including bacterial infection.

SUMMARY

Knowledge of the characteristic imaging and clinical features of bacterial respiratory infections can enhance their timely diagnosis and treatment.