Previous studies conducted in high-risk populations have reported high predictive values and accuracies for diagnostic imaging techniques for aortic dissection. To see how these techniques perform in low-risk populations, we used Bayes' theorem to calculate predictive values and accuracies for angiography, CT, MRI, and TEE. In high-risk populations (disease prevalence = 50%), positive predictive values were all greater than 85%. In intermediate risk populations (disease prevalence = 10%), positive predictive values were greater than or equal to 90% for CT, MRI, and TEE, but were 65% for angiography. In low-risk populations (disease prevalence = 1%), positive predictive values were 100% for MRI and less than or equal to 50% for angiography, CT, and TEE. In all three populations, negative predictive values and accuracies were greater than or equal to 85%. From these results we conclude that diagnostic imaging techniques for aortic dissection do not perform as well in low-risk populations as they do in high-risk populations.