From the Guidelines
The initial diagnostic imaging study of choice for suspected aortic dissection is a CT scan, due to its wide availability, accuracy, and speed, as well as the extent of anatomic detail it provides. According to the 2022 ACC/AHA guideline for the diagnosis and management of aortic disease 1, CT is recommended for initial diagnostic imaging in patients with suspected aortic dissection. The guideline assigns a Class of Recommendation (COR) of 1 and a Level of Evidence (LOE) of C-LD to this recommendation, indicating that CT is the preferred initial imaging modality.
The advantages of CT include:
- Wide availability
- High accuracy
- Rapid acquisition time
- Extent of anatomic detail provided As noted in the guideline, CT, TEE, and MRI are all highly accurate for the diagnosis of aortic dissection, but CT is preferred due to its widespread availability and speed 1.
Alternative imaging options, such as TEE and MRI, are reasonable alternatives for initial diagnostic imaging, as assigned a COR of 2a and a LOE of C-LD by the guideline 1. However, these modalities may have limitations, such as reduced availability in emergency situations or longer acquisition times.
In patients with suspected aortic dissection, it is essential to prioritize rapid and accurate diagnosis to guide treatment and improve outcomes. The choice of imaging study should be guided by the patient's clinical presentation, hemodynamic stability, and availability of imaging modalities.
From the Research
Diagnostic Options for Suspected Aortic Dissection
The following diagnostic options are available for suspected aortic dissection:
- Transesophageal echocardiography (TEE)
- Helical computed tomography (CT)
- Magnetic resonance imaging (MRI)
- Computed tomographic angiography (CTA)
- Magnetic resonance angiography (MRA)
- Transthoracic echocardiogram (TTE)
Study Recommendations
Based on the available evidence, the following studies can be recommended:
- For patients with suspected thoracic aortic dissection, TEE, helical CT, and MRI yield clinically equally reliable diagnostic values for confirming or ruling out thoracic aortic dissection 2.
- Spiral CT and multiplanar TEE are as valuable as MR imaging in the detection of thoracic aortic dissection, while spiral CT is superior in the assessment of the supraaortic branches 3.
- MRA can guide ED management of suspected acute aortic dissection, especially in patients with contraindicions to CTA 4.
- TTE/TEE can be used to rule in or rule out the diagnosis of aortic dissection when the clinical suspicion is high and CTA is not conclusive 5.
Key Findings
- The pooled sensitivity and specificity of TEE, helical CT, and MRI are comparable, with sensitivity ranging from 98-100% and specificity ranging from 95-98% 2.
- The detection rate of the intimal flap was 100% in all segments of the aorta using intravascular ultrasound (IVUS) 6.
- MRA has a clear role in the evaluation for acute thoracic aortic dissection in the ED in patients with contraindications to CTA 4.