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CE-MRA of supraaortic arteries over 350 mm FOV

Best Practice
Willinek, Winfried, M.D. Bonn, University of Bonn

 

Despite advances in CE-MRA of the supraaortic arteries, most current methods still struggle to meet the conflicting demands of high spatial resolution, sufficient anatomical coverage and arterial phase imaging. University of Bonn clinicians led by Winfried A.Willinek, M.D., however, have been using Philips' CENTRA and CLEAR techniques to create - in a single exam - highly detailed, arterial phase images encompassing the carotid and vertebral arteries from the aortic arch up to the circle of Willis.

 


Winfried A.Willinek, M.D. University of Bonn
Winfried A.Willinek, M.D.
University of Bonn

CENTRA ideal for high-resolution imaging of supraaortic arteries

An innovative Philips k-space sampling method is proving to be the solution for satisfying the divergent requirements of CE-MRA of the supraaortic vessels. At the University of Bonn, Dr. Willinek has used CENTRA k-space ordering in its CE-MRA examinations of the supraaortic arteries since 2000 and has accumulated over 400 cases.

Small voxels, large coverage, no venous contamination

CENTRA - Contrast-Enhanced Timing- Robust Angiography - is similar to existing elliptic centric view ordering techniques, but with a critical difference.

 

"CENTRA acknowledges that most of the contrast encoding is determined by the center of k-space, whereas outer k-space determines spatial resolution and contributes little to image contrast. By sampling the center of k-space first - during arterial passage of contrast - and then moving outward in k-space while extending data acquisition well beyond the arterial phase, CENTRA enables acquisition of high spatial resolution, high vessel-versus-tissue contrast without venous contamination," Dr. Willinek explains. "In contrast to other methods, however, CENTRA is less prone to timing errors than other methods due to the random segmentation of k-space. While the start of data sampling in other methods must correspond with the bolus peak, CENTRA allows sampling both during the upslope and tail of the contrast-over-time curve. This results in MRAs with homogenous vessel contrast and decreased artifacts due to unstable arterial opacification."

 


48-year-old male patient presenting with amaurosis fugax. Coronal, contrast-enhanced 3D MR angiography using CENTRA covers the brain supplying arteries from the aortic arch up to the circle of Willis without venous overlay.

 

   "CENTRA has become Bonn's

    front-line diagnostic tool for

    cerebrovascular disease."


Radiology paper describes excellent results with CENTRA

In Dr. Willinek's recent publication on CE-MRA using CENTRA1, investigators prospectively studied 16 consecutive patients with suspected cerebrovascular disease. The CENTRA protocol - sufficient to cover the entire region of interest in a single exam - used a 432 x 432 matrix on a 350 mm FOV with 60 slices of 1 mm, yielding an almost isotropic voxel size of 0.81 x 0.81 x 1.0 mm. Philips' BolusTrak was used to time the start of data acquisition. In a subset of six patients, conventional DSAs were available for comparison.

 

"For the total of 240 vascular territories evaluated, observers judged arterial delineation to be excellent in 98 percent of territories. In addition, overall diagnostic quality was judged excellent or more than adequate for diagnosis in 100 percent of the MRAs and venous signal was lower than arterial signal in all cases," Dr. Willinek notes. "When the MRAs were compared with the six DSAs, observers reported a strong correlation between the degree of luminal stenosis depicted on MRAs and that shown on the DSAs."

 


                 Image 1                                   Image 2                                   Image 3

Image 1

CE-MR angiogram of a 65-year-old male with suspected left subclavian steal syndrom.With the extensive anatomic coverage provided by high spatial resolution MRA using CENTRA, diagnosis of a severe stenosis of the left proximal subclavian artery (arrow), detection of an asymptomatic stenosis of the right ICA (arrowhead) and visualization of the circle of Willis are possible within a single examination.

 

Image 2

High spatial resolution CE-MRA using CENTRA in a 68-year-old male. Right ICA occlusion was suspected by duplex ultrasound. However, high grade right ICA stenosis with secondary hypoplasia (arrows) was depicted on the enlarged sagittal view of the MR angiogram (left image).

 

Image 3

67-year-old male presenting with cerebral TIA. An incidental, 5 mm left MCA aneurysm is visualized on high spatial resolution CE-MRA using CENTRA (arrow).

 


Enlarged sagittal views of the right ICA. High grade stenosis and ulceration of atheromatous carotid plaque is displayed on high spatial resolution CE-MRA using CENTRA (left). In this patient, DSA was available for comparison and confirmed the MRA diagnosis (right).

 


 


 

With the success of CENTRA in this small clinical study, Dr. Willinek's group has initiated an intraindividual comparative study in a larger patient group - comparing CE-MRA with DSA prospectively for detection of stenosis and occlusion. "Preliminary results show a strong correlation between CE-MRA using CENTRA and DSA," he says2.

 

 

"Today, Bonn conducts 25-30 CENTRA CE-MRAs per month and the study has become the medical center's front-line diagnostic tool for patients presenting with cerebrovascular disease."

 



References:

 

1.W.A.Willinek et. al.

Randomly Segmented Central k-space Ordering in High-Spatial-Resolution Contrast-enhanced MR Angiography of the Supraaortic Arteries: Initial Experience.

Radiology Nov. 2002,Vol. 225, No. 2, p583-588

 

2.W.A.Willinek et. al.

CE-MRA of the supraaortic arteries at 512 and 1024 matrix: the use of randomly segmented central k-space ordering (CENTRA).

Proc 10th Meeting ISMRM: 2002; 14



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Best Practice
Achieva 1.5T, Intera 1.5T
Carotid, Supra aortric arteries, Vascular
 

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