A new imaging method for assessment of aortic dissection using four-dimensional phase contrast magnetic resonance imaging

Introduction Medical management of type B aortic dissection can result in progressive dilation of the false lumen and poor long-term outcome. Recent studies using models of aortic dissection have suggested flow characteristics, such as stroke volume, velocity, and helicity, are related to aortic exp...

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Published in:Journal of vascular surgery 2012-04, Vol.55 (4), p.914-923
Main Authors: Clough, Rachel E., MBBS, BSc, MRCS, Waltham, Matthew, MA, PhD, FRCS, Giese, Daniel, Dipl Phys, Taylor, Peter R., MA, MChir, FRCS, Schaeffter, Tobias, PhD
Format: Article
Language:English
Subjects:
Aged
Aged, 80 and over
Aneurysm, Dissecting - diagnosis
Aneurysm, Dissecting - surgery
Aortic Aneurysm, Thoracic - diagnosis
Aortic Aneurysm, Thoracic - surgery
Biological and medical sciences
Blood and lymphatic vessels
Cardiology. Vascular system
Cohort Studies
Contrast Media
Diseases of the aorta
Female
Four-Dimensional Computed Tomography - methods
Humans
Magnetic Resonance Angiography - methods
Magnetic Resonance Imaging - methods
Male
Medical sciences
Middle Aged
Prospective Studies
Radiographic Image Enhancement
Sensitivity and Specificity
Severity of Illness Index
Surgery
Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases
Vascular surgery: aorta, extremities, vena cava. Surgery of the lymphatic vessels
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Summary:Introduction Medical management of type B aortic dissection can result in progressive dilation of the false lumen and poor long-term outcome. Recent studies using models of aortic dissection have suggested flow characteristics, such as stroke volume, velocity, and helicity, are related to aortic expansion. The aim of this study was to assess whether four-dimensional phase-contrast magnetic resonance imaging (4D PC-MRI) can accurately visualize and quantify flow characteristics in patients with aortic dissection and whether these features are related to the rate of aortic expansion. Methods Twelve consecutive patients with medically treated type B thoracic aortic dissection underwent a three-dimensional (3D) MRI anatomy scan using a blood pool contrast agent. Two-dimensional phase contrast MRI data (2D PC-MRI) were acquired in the ascending and descending aorta and 4D PC-MRI data were acquired in the entire thoracic aorta. The 2D PC-MRI measurements were used to assess the quality of the 4D PC-MRI velocity data. Stroke volume, velocity, and the direction of flow were calculated using 4D PC-MRI and related to the rate of aortic expansion measured on contrast-enhanced computed tomography. Results Comparison of 2D PC-MRI and 4D PC-MRI measurements showed good correlation (Pearson R 2 = 0.98; 95% confidence interval [CI], 0.9818-0.9953; P < .0001) and no proportional bias (bias = 1.0 mL; standard deviation, 4.6). The median aortic growth rate was 6.1 mm/y (interquartile range [IQR], 1.1-15.1 mm/y), and this correlated well with the growth rate of the false lumen (Spearman ρ = 0.62; 95% CI, 0.06-0.89; P = .0347). False lumen thrombosis (FLT) was seen in 7 of 12 patients and was not associated with reduced aortic expansion rate (FLT present: 11.4 mm/y; IQR, 3.6-21.4) vs FLT absent: 9.9 mm/y; IQR, 3.4-24.2; Mann-Whitney P = .8763). False lumen stroke volume and velocity were associated with more rapid aortic expansion ( ρ = 0.80 [95% CI, 0.39-0.94; P = .0029] and ρ = 0.59 [95% CI, 0.09-0.87; P = .0480] respectively). The position of the dominant entry tear was associated with rapid expansion, which tended to be higher with distal vs proximal entry tears (distal, 21.4 mm/y [IQR, 11.4-48.9] vs proximal, 5.5 mm/y [IQR, 3.4-16.6]; Mann-Whitney P = .096). Helical flow was seen in the false lumen in 8 of 12 patients and was related to the rate of aortic expansion ( ρ = 0.83, P = .0154). Conclusions 4D PC-MRI can be accurately applied to visualize and quantify flow chara
ISSN:0741-5214
1097-6809
DOI:10.1016/j.jvs.2011.11.005