Thoracic aortic injury: how predictive is mechanism and is chest computed tomography a reliable screening tool? A prospective study of 1,561 patients.

BACKGROUND: Thoracic aortic injury (TAI) is a devastating condition in which prompt recognition can obviate morbidity and mortality. It is a long-held belief that TAI is more likely when there is a "major mechanism of injury." The purposes of this prospective study were to determine mechanism characteristics that are predictive of TAI and to evaluate chest computed tomography (CT) as a screening tool for TAI. METHODS: Over a 5 1/2 year period, blunt chest trauma patients at two Level I trauma centers were evaluated for potential TAI. Patients were assigned mechanism and radiograph scores from 1 (low suspicion for TAI) to 5 (very high suspicion for TAI). Immediate aortography was obtained when suspicion for TAI was very high. The remaining patients were evaluated with contrast-enhanced chest CT. Confirmatory aortography was obtained on all positive chest CT scans and on all patients with mechanism scores of 4 or 5 even if the CT was negative. Mechanism and radiographic data were correlated with the results of aortic imaging. RESULTS: Of the 1,561 patients evaluated for TAI, 30 aortic injuries were found. The assessment of mechanism was imperfect with a reliance on often incomplete and subjective data. The subjective mechanism score proved to be the most useful predictor of TAI. Radiographic scores were useful but insensitive for intimal injuries. Computed tomography was found to have 100% and 100% NPV for TAI. CONCLUSION: Considering the inherent difficulties in identifying patients at risk for TAI and the effectiveness of chest CT as a screening tool for aortic injury, we recommend liberal use of chest CT in blunt chest trauma. Guidelines for determining the need for aortic imaging are outlined.

Can chest CT be used to exclude aortic injury?

PURPOSE: To determine whether chest computed tomography (CT) can be used to exclude aortic injury. MATERIALS AND METHODS: Patients in whom there was very high suspicion of traumatic aortic injury were examined with aortography only. Other patients were examined with contrast material-enhanced CT. Follow-up aortography was performed in all patients with moderate to high suspicion of traumatic aortic injury and in all patients with CT scans that were positive for traumatic aortic injury. CT scans were regarded as positive when they showed mediastinal hematoma or direct findings of aortic injury. During a 4 1/2-year period, 1,009 patients (263 female, 746 male; age range, 3-90 years) were evaluated for possible traumatic aortic injury. RESULTS: Of the 207 patients who underwent aortography directly without CT, 10 had traumatic aortic injury. Of the 802 patients who were examined with CT, 382 underwent follow-up aortography. In this group, there were 10 true-positive and no false-negative CT scans. CT had 100% sensitivity and a 100% negative predictive value for the detection of traumatic aortic injury.

Posterior fossa venous angiomas with drainage through the brain stem.

PURPOSE: To describe 11 cases of posterior fossa venous angiomas with drainage through the brain stem. METHODS: Eleven cases of posterior fossa venous angioma with drainage through the brain stem were evaluated using MR. Correlation with known routes of venous drainage for the cerebellum and brain stem is made. RESULTS: Six of the 11 venous angiomas were found in the cerebellum, four in the brain stem; one involved both the cerebellum and brain stem. The cerebellar venous angiomas drained to subependymal veins about the fourth ventricle and dorsal pons. These then connected with an enlarged transmesencephalic or transpontine vein, to drain anteriorly to the anterior pontine veins. The brain stem angiomas had variable drainage depending on location. Evidence of hemorrhage was seen in five cases. CONCLUSION: Cerebellar and brain stem venous angiomas have several potential routes of drainage, including an enlarged vein traversing the pons, midbrain, or medulla. A knowledge of the normal venous anatomy of this region helps to understand the occurrence of these uncommon routes of venous drainage.

Polyamine metabolism in liver of young rats.

Rat liver undergoes a phase of rapid growth during weaning. We followed the changes in polyamine metabolism occurring during this period of natural growth, and compared them with changes in DNA and RNA accumulation. There was a 2.5-fold increase in the number of cells per liver between suckling (18--19 days old) and weaning (30--32 days old) rats. Ornithine decarboxylase activity increased from the low value in 18-day-old rat pups and remained significantly higher (approx. 5--10-fold) than that in adult rats from day 21 to day 34. Putrescine-dependent S-adenosylmethionine decarboxylase activity was slightly but significantly increased during most of this period. Spermidine and RNA concentrations fluctuated in concert, whereas spermine content per cell doubled during the period from day 23 to day 30.

Analysis of spermidine and spermine in rat liver. Effect of hypophysectomy on polyamine concentrations.

A simple, rapid, reproducible assay for tissue polyamines using a standard unmodified amino-acid analyzer is described. This technique will allow accurate measurement of the polyamines from as little as 10 mg of liver in less than 1 h. We have used this method to establish the optimum conditions for the extraction of polyamines from liver and to study the effects of hypophysectomy on polyamine content of rat liver. Hypophysectomy caused a fall in RNA, protein, putresine, and spermidine content prevented the normal increase in spermine in rat liver seen with increasing age.