CT of the azygoesophageal recess in infants and children

Normal mediastinal and hilar lymph nodes in children on multi-detector row chest computed tomography

Objective

To study normal mediastinal and hilar lymph nodes on multi-detector chest computed tomography (CT).

Methods

A cohort of 120 children aged 1–17 years underwent emergency CT, including the chest, after high-energy trauma. Axial 5-mm reconstructions were evaluated for lymph nodes at hilar and various mediastinal levels and the short-axis diameters were measured.

Results

At least one lymph node was found in 115 (96%) children, with subcarinal (69%), lower paratracheal (64%) and hilar (60%) nodes being most common. Up to 10 years of age most lymph nodes were smaller than or equal to 7 mm. In older children lymph nodes measuring up to 10-mm-short-axis diameter were found. Lymph nodes were rare along the mammary vessels, at lower oesophageal and at prevascular and posterior mediastinal levels in children.

Conclusion

Mediastinal and hilar lymph nodes are more common than previously thought, probably because of increased detection by modern multi-detector CT. Lymph node location and age have to be taken into account when evaluating lymph nodes in the paediatric chest.

Key Points

• The size and location of normal lymph nodes is of great diagnostic importance

• There is little relevant published information related to pediatric chest computed tomography

• We provide normative data concerning mediastinal and hilar lymph nodes in children

• These normal values can help identify abnormal lymph nodes in children

Diagnostic accuracy of chest radiography in detecting mediastinal lymphadenopathy in suspected pulmonary tuberculosis

OBJECTIVE

To estimate the diagnostic accuracy of chest radiography in the detection of chest lymphadenopathy in children with clinically suspected pulmonary tuberculosis.

DESIGN

Prospective cross sectional study.

SETTING

A short stay ward in a children's hospital in South Africa.

PATIENTS

Consecutive children under 14 years of age admitted with suspected pulmonary tuberculosis.

DIAGNOSTIC TEST

Antero-posterior and/or lateral chest x rays interpreted independently and blind to the reference standard by three primary care clinicians and three paediatricians, all with a special interest in tuberculosis. Reference standard: Spiral chest computed tomography (CT) with contrast injection.

RESULTS

One hundred children (median age 21.5 months) were enrolled. Lymphadenopathy was present in 46 of 100 reference CT scans and judged to be present in 47.1% of x ray assessments. Overall sensitivity was 67% and specificity 59%. Primary care clinicians were more sensitive (71.5% v 63.3%, p = 0.047) and less specific (49.8% v 68.9%, p<0.001) than paediatricians. Overall accuracy was higher for the paediatricians (diagnostic odds ratio 3.83 v 2.49, p = 0.008). The addition of a lateral to an antero-posterior view did not significantly increase accuracy (diagnostic odds ratio 3.09 v 3.73, p = 0.16). Chance adjusted inter-observer agreement (kappa) varied widely between viewer pairs, but was around 30%.

CONCLUSIONS

Detection of mediastinal lymphadenopathy on chest x ray to diagnose pulmonary tuberculosis in children must be interpreted with caution. Diagnostic accuracy might be improved by refining radiological criteria for lymphadenopathy.