What is the sensitivity and specificity of widened mediastinum based on chest X-ray for diagnosing aortic dissection?

The Bottom Line: In this study, the maximal mediastinal width and maximal left mediastinal width were measured by two independent radiologists and the mediastinal width ratio was calculated. Statistical analysis was then performed with independent sample t test. Postanterior projection was significantly more accurate than anteroposterior projection, achieving higher sensitivity and specificity. Left mediastinal width and mediastinal width were the most powerful parameters on postanterior and anteroposterior chest radiographs, respectively. The optimal cutoff levels were LMW 04.95 cm (sensitivity, 90%; specificity, 90%) and MW 07.45 cm (sensitivity, 90%; specificity, 88.3%) for PA projection and LMW 05.45 cm (sensitivity, 76%; specificity, 65%) and MW08.65 cm (sensitivity, 72%; specificity, 80%) for AP projection.

Lai, Vincent. Diagnostic accuracy of mediastinal width measurement on posteroanterior and anteroposterior chest radiographs in the depiction of acute nontraumatic thoracic aortic dissection. Emergency radiology 2012 vol:19 iss:4 pg:309 -315

Aortic dissection is not infrequent with reported incidence of 5–10 out of 1,000,000/year. However, patients often present with nonspecific clinical symptoms raising diagnostic difficulty.

Table 1 Comparison of optimal cutoff values of MW and LMW for best diagnostic power between PA and AP chest radiographs Page 313

Table 2 Comparison of cutoff values of MW and LMW to achieve 100% sensitivity between PA and AP chest radiographs Page 313

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