Determination of normal transverse mediastinal width and mediastinal-width to chest-width (M/C) ratio in control subjects: implications for subjects with aortic or brachiocephalic arterial injury.
We measured transverse mediastinal width and mediastinal-width to chest-width (M/C) ratio on supine films of 100 nontraumatized controls. In 95% the transverse mediastinal width was less than 7.5 cm and the M/C ratio was less than 0.38. Thus a transverse width of 7.5 cm or more or an M/C ratio of 0.38 or more can be defined as abnormal with 95% confidence. Application of these values to determine abnormality in 32 patients with proven aortic or brachiocephalic injury showed that the transverse mediastinal width was within normal limits in 41% and M/C ratio was normal in 69%. Utilizing smaller values that would identify all abnormals resulted in false positive rates in the controls of 74% and 87%, respectively. However, one or more of eight specific signs of mediastinal abnormality related to hemorrhage or pseudoaneurysm formation were present in 94% of abnormals compared to only 11% of controls. Because of extreme overlap of transverse mediastinal width and M/C ratio between normals and abnormals, precise measurement of the mediastinum cannot reliably separate the two groups. The subjective assessment of anatomic mediastinal abnormality remains a superior plain film method in determining the need for aortography.
Woodring
J H
JH
Department of Diagnostic Radiology, University of Kentucky Medical Center, Lexington 40536-0084.
King
J G
JG
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging / Q000293:injuries*; D016122:Brachiocephalic Trunk / Q000000981:diagnostic imaging / Q000293:injuries*; D006801:Humans; D008482:Mediastinum / Q000473:pathology*; D008875:Middle Aged; D011859:Radiography; D013898:Thoracic Injuries / Q000000981:diagnostic imaging* / Q000473:pathology; D013909:Thorax / Q000473:pathology; D014949:Wounds, Nonpenetrating / Q000000981:diagnostic imaging / Q000473:pathology