Aortic dissection: MRI was the best imaging study

Clinical bottom line (level 1b)

Roughly 55% of patients with a suspected aortic dissection had one.
MRI could diagnose and exclude aortic dissection.
CT, transthoracic and transoesophageal echocardiography made aortic dissection more likely if positive, but could not safely exclude it.

Nienaber et al: New England Journal of Medicine 1993; 328 : 1-9

Expires October 2004

The study

Setting: 2 medical centers in Germany

110 patients (aged 19 to 96; mean 54, 64% male) referred with suspected dissection of the thoracic aorta.

Excluded if

if chronic dissection

Independent blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
Reference standard:

aortography, surgery, and autopsy. Angiography positive if intimal flap or double lumen in aorta seen.

Diagnostic test:

transthoracic echocardiography: positive if 2 vascular lumens separated by an intimal flap
tranoesophageal echocardiography in 70 patients: positive if 2 vascular lumens separated by an intimal flap. If subacute symptoms, patients fasted for one hour.
Third-generation CT scanners in 79 patients. Positive if an abrupt transition to a larger lumen at the origin of a side branch, the visualization of a dissecting membrane, or the presence of a poorly opacified crescent portion of the aorta
whole body MRI in 105 patients; positive if 2 separated lumens.

There were 2 or 3 blinded interpreters for each study.

The evidence

pre-test probability of aortic dissection: 55%, (95% CI: 45% to 64%)

diagnostic test	aortic dissection	no aortic dissection	LR+ (95% CI)	post-test probability	LR- (95% CI)	post-test probability
MRI	58	1	45 (6.5 to 310)	98%	0.017 (0.013 to 0.022)	2%
total	59	46

diagnostic test	aortic dissection	no aortic dissection	LR+ (95% CI)	post-test probability	LR- (95% CI)	post-test probability
TEE	43	6	4.2 (2.1 to 8.6)	84%	0.030 (0.004 to 0.20)	4%
total	44	26

diagnostic test	aortic dissection	no aortic dissection	LR+ (95% CI)	post-test probability	LR- (95% CI)	post-test probability
CT thorax	45	4	7.3 (2.9 to 18)	90%	0.071 (0.023 to 0.22)	8%
total	48	31

diagnostic test	aortic dissection	no aortic dissection	LR+ (95% CI)	post-test probability	LR- (95% CI)	post-test probability
TTE	37	8	3.5 (1.8 to 7.0)	81%	0.49 (0.34 to 0.67)	37%
total	62	48

Comments

MRI is best test, but takes longer than echo (23 +/- 3 min v. 13 +/- 6 min: mean difference 10 min 95% CI: 8% to 12%).
32 patients had a type A dissection - 8 were subacute. 26 had surgery and 6 died.
30 patients had a type B dissection - 19 were subacute. 15 went on to have surgery, and 3 died.

Citation

Nienaber CA, von Kodolitsch Y, Nicolas V, et al: The diagnosis of thoracic aortic dissection by noninvasive imaging procedures. New England Journal of Medicine 1993; 328 : 1-9

Search Terms: aort* near dissect* in Cochrane
Contributor: Chris Ball, Clare Wotton, October 2001
Reviewer:

_{Clinical Question.}

_Patient	_{suspected aortic dissection referred for angiography}
_{Intervention or Exposure}	_{CT thorax, MRI thorax, transoesophageal or transthoracic echocardiogram}
_Outcome	_{aortic dissection}