First thoracic vertebral body as reference for endotracheal tube placement.

After intubation in newborn infants, the placement of the endotracheal tube in the trachea must be checked by a chest radiograph. The most commonly used reference point for placement is the medial ends of the clavicles. The position of the clavicles may be variable. The present study was carried out to determine whether the body of the first thoracic vertebra should be used instead of the clavicles because its position on chest radiographs is more constant. Seventy eight radiographs obtained from 35 neonates were examined prospectively. The carina was situated between T3 and T5, most commonly at T3-4 or T4 (85%). The position of the clavicles varied markedly from patient to patient and within the same patient on different days, and this variation was significantly higher than that of the carina. On 65 (83%) examinations the clavicles lay above the first thoracic vertebra. It is recommended that, for accurate placement within the trachea, the tip of the endotracheal tube should be placed at the level of the body of the first thoracic vertebra; this could be used as the sole reference point on chest radiographs obtained in the neonatal period.

Comparison of magnetic resonance angiography and contrast arteriography in peripheral arterial stenosis.

Magnetic resonance angiography (MRA) has recently been shown to be more sensitive than contrast arteriography in the detection of patent distal runoff vessels. This study compares MRA and contrast arteriography in evaluating the severity of stenotic lesions in peripheral arteries, which has not been previously investigated. Forty-eight arterial stenoses (19 patients) were identified, from the distal aorta through the crural vessels. Contrast arteriograms (anterioposterior projection) and MRA axial images were used to measure stenoses. Interobserver agreement of arteriogram readings was excellent (average weighted k = 0.87). Measurements of degree of stenosis as evaluated by MRA and contrast arteriography were analyzed by linear regression and Spearman rank correlation, which showed a high degree of correlation between the two diagnostic modalities (r = 0.83, p < 0.001; rs = 0.84, p < 0.001). These observations suggest that MRA is accurate in the evaluation of peripheral arterial stenosis when compared with the "gold standard" contrast arteriogram. In addition, MRA cross-sectional images provide information beyond that of conventional arteriography, showing details of plaque eccentricity and vessel wall characteristics. In the future, MRA may supplant diagnostic contrast arteriography for many patients.