[Various spiral CT protocols and their significance in the diagnosis of aortic dissections: results of a prospective study].

PURPOSE: Development of an optimized Spiral CT protocol type for the diagnosis of aortic dissections.

MATERIAL AND

METHODS

121 consecutive CT examinations applying 5 different protocol types were blindly read by two experienced radiologists and then compared with: (a) 45 biplane transesophageal echocardiographies (TEE), (b) 52 transthoracic echocardiographies (TTE), (c) 52 operative findings and, furthermore, related to the clinical course over at least six months in 79 patients.

RESULTS

The sensitivity of the spiral computed tomography for detection of dissection was 97% (biplane TEE: 88%), the specificity 100% (biplane TEE: 91%). In 15% dissections with atypical origin and entries (mid-portion of the aortic arch, distal thoracic aorta, etc.) were found. The optimal CT-protocol was the one with a combination of two separate but adjacent spiral scans achieving high spatial resolution for the aortic arch and enough spatial resection for the residual aorta (1. helical scan 3 mm collimation, pitch 2. 2. helical scan 5 mm collimation and pitch 2, 130 ml contrast medium at 5 ml/s) with a classification accuracy of 100%, visualization of entries of 100%, reentries of 100% (40% direct, 60% indirect). The identification of the ostia of the aortic branches were: supraaortic 93%, visceral 100%, left renal artery 100%, right renal artery 93%, iliac 64%. The CT angiography, designed as aortic arch angiography, showed a good contrast in the aortic arch vessels (79-86%) and the visceral vessels too (91%).

CONCLUSION

Thoracic CT angiography can be used as gold standard in the primary evaluation of aortic dissections.