Diagnostic value of nonenhanced multidetector computed tomography for ruling out acute aortic dissection in patients presenting with chest or back pain.

BACKGROUND: Multidetector computed tomography (MDCT) is widely used for diagnosing acute aortic dissection (AAD). However, the diagnostic value of nonenhanced MDCT for AAD remains unknown. We evaluated the usefulness of nonenhanced 64-slice MDCT for ruling out AAD in patients presenting with chest or back pain.

METHODS: Of 107 patients with clinical suspicion of AAD who underwent MDCT, AAD was confirmed in 47 and ruled out in 60. Nonenhanced MDCT data of all patients were retrospectively assessed by 2 independent observers unaware of clinical information and contrast-enhanced MDCT data. The diagnostic performance of nonenhanced MDCT parameters to detect AAD was calculated.

RESULTS AND CONCLUSION: Among the parameters, positive intimal flap, defined as the clear presence of a high-density membrane-like structure in the aorta on serial axial images, had a sensitivity of 87%, a specificity of 100%, a positive predictive value (PPV) of 100%, and a negative predictive value (NPV) of 91%, respectively. The addition of equivocal intimal flap, defined as the ambiguous presence of a high-density membrane-like structure in the aorta on at least one axial image, increased both the sensitivity and NPV to 96%. Furthermore, the combination of intimal flap (positive+equivocal or positive alone) and high-density area in the aorta showed the highest sensitivity (98%) and NPV (98%). Combination of the nonenhanced MDCT parameters intimal flap and high-density area in the aorta provides excellent sensitivity and NPV, suggesting that nonenhanced MDCT is an effective modality for ruling out AAD in patients with chest or back pain.