Dynamic pulmonary CT of children.

ABSTRACT

OBJECTIVE: Wide-detector CT allows simultaneous imaging of the entire airway and lungs in small children. Images acquired in multiple phases by continuous scanning during respiration are viewed dynamically, allowing more complete airway and pulmonary evaluation than possible with static protocols. The purpose of this study was to evaluate whether low-dose techniques can be applied to dynamic pulmonary CT of small children. MATERIALS AND METHODS: The study included 24 infants and small children with persistent respiratory difficulty who underwent dynamic pulmonary CT (11 with IV contrast administration, 13 without contrast administration). No significant difference in patient age was present in the two groups. Continuous-mode wide-detector scans were obtained at 350-millisecond gantry rotation for a total of 1.4 seconds at 80 kVp. Some contrast-enhanced studies for simultaneous vascular and airway evaluation were performed at slightly greater tube current. The effective dose for each patient was calculated, and the Student t test was performed to compare effective dose measurements. RESULTS: All studies were of diagnostic quality, frequently yielding critical information not available with other diagnostic tests. The mean effective dose for all patients was 1.7 (SD, 1.1) mSv. In the group who received contrast material, the mean effective dose was greater (1.9 [SD, 1.4] mSv) than in the group who did not receive contrast material (1.5 [SD, 0.7] mSv), but the difference was not significant (p = 0.4). CONCLUSION: Wide-detector dynamic CT is ideal for evaluation of the airway and lungs in infants and small children with persistent respiratory distress. Effective doses are low, typically less than 2 mSv.