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Ingenia 1.5T helps to advance MR angiography at Utrecht

Best Practice
Leiner, Tim, M.D., Ph.D. UMC Utrecht • Netherlands

University Medical Center (UMC) Utrecht was the first in the world to install a Philips Ingenia 1.5T scanner. Now, one year on, the radiology department has built up considerable expertise in working with the system. According to Tim Leiner, MD, PhD, cardiovascular radiologist and Associate Professor of Radiology at UMC, Ingenia provides high SNR and a large, homogenous field of view which benefit quality and speed of MRA exams.

 Tim Leiner, MD, PhD
Tim Leiner, MD, PhD

“Some key features of Ingenia really benefit MRA,” says Dr. Leiner. “The high SNR provided by dStream, the large coverage, and the high SENSE factors can be used to improve spatial resolution and speed up scanning. In addition, patient positioning is really easy with the integrated Posterior coil combined with, for instance, the lightweight Anterior coils for peripheral MRA or with the dS HeadSpine coil for carotid MRA with coverage including the aortic arch and isotropic resolution of 1.0 x 1.0 x 1.0 mm3. MRA of the upper extremities can be challenging, but Ingenia 1.5T offers gorgeous image quality without signal drop-off at the edge of the FOV.”

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Easier patient positioning and scan planning

“Ingenia 1.5T has allowed us to greatly increase the coverage in peripheral MRA exams,” he says. “For instance, we often had to scan the peripheral arteries with rather limited anteroposterior coverage, which made it somewhat difficult to include all the relevant anatomy. Now with Ingenia, it’s possible to scan thick volumes in every station with a wide coverage in both anterior-posterior and the left-to-right direction, including all the relevant anatomy. This makes it much easier for the technologist to position the scanning volumes, which means both patient setup and planning can now be done really quickly.”


The department’s acquisition protocol for peripheral MRA with the Ingenia 1.5T shows substantial increases in coverage of about 35% in the aortoiliac station, 70% in the upper legs and more than 40% in the lower legs. Still, scan time is kept short with SENSE factors of 4 to 5 in every station which, according to Dr. Leiner, is a great advance on what was available previously.



  







Easier trade-off and reduced contrast dose

“Contrast-enhanced peripheral MRA requires a trade-off between the high spatial resolution needed for visualizing small stenoses, and the scan time,” says Dr. Leiner. “Longer imaging provides higher resolution but more of the contrast bolus will have reached the venous system, which may lead to sub-optimal images. However, this trade-off between best possible spatial resolution and short imaging times is much less stringent with the technology advances that Ingenia offers.”


With its digital architecture, Ingenia 1.5T provides larger coverage and up to 40%increase in SNR. “We are performing tests to see if the increased SNR can be used to reduce contrast dose without compromising image quality. This will not only benefit the patient but also save on costs,” he explains. “In our initial results we see beautiful enhancement throughout the full coverage.”


According to Dr. Leiner, the Ingenia 1.5T system has lived up to expectations in all areas, especially in one of his own areas of interest – peripheral MRA. “Large coverage and high SNR provided by the Ingenia assure high image quality with minimal trade-off between resolution and speed.”


Click on the images to enlarge them for better appreciation of the high resolution.



SIDEBAR

mDIXON* halves exam times

According to Dr. Leiner, another important development that has a tremendous impact on peripheral MRA is the Philips multipoint Dixon method.


In a normal contrast-enhanced MRA procedure, a non-contrast-mask scan is initially acquired, then the contrast is administered and exactly the same scan with contrast is acquired. Image subtraction will then eliminate the signal of non-arterial tissues such as muscle and subcutaneous fat. But this comes at the price of increased scan time and reduced SNR.


With mDIXON however, it is possible to obtain water-selective images. “With Ingenia 1.5T we can immediately administer contrast and perform fast mDIXON imaging to obtain a water-selective image which has intrinsic background suppression, eliminating the need for subtraction,” Dr. Leiner explains. “So using mDIXON helps to reduce scan time by about 50%. In addition, it eliminates disadvantages of having to perform a subtraction such as motion artifacts and SNR loss.”

Peripheral MRA using subtractionless mDIXON

 MIP no subtraction MIP subtraction MIP mDIXON, no subtraction
MIP no subtraction
MIP subtraction
MIP mDIXON, no subtraction

Click on the images to enlarge them for better appreciation of the high resolution.


65-year-old male with bilateral intermittent claudication. Left image shows MIP of non-subtracted first pass MRA. Center image shows the improvements after subtracting the pre-contrast mask scans from the contrast-enhanced data. The relatively poor vessel-to-background contrast below the knee is due to the low contrast dose. The mDIXON image, obtained without subtraction, shows excellent background suppression and allows accurate assessment of aortoiliac stenoses on the right, as well as bilateral upper leg occlusions and small collaterals. Also note the superior depiction of lower leg arteries with mDIXON.
Ingenia 1.5T is used with the Anterior and the integrated Posterior coils (28 elements in each station). The actual spatial resolution ranges from 1.3 x 1.3 x 2.8 mm 3 in the aortoiliac station to  1.0 x 1.0 x 1.5 mm 3 in the lower leg station. dS SENSE parallel imaging was used to achieve an  8- to 10-fold acceleration, leading to scan times between 16 sec. for the first station and 25 sec. for the third station.

 

*mDIXON for vascular imaging is not yet commercially available




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Best Practice
Ingenia 1.5T
Release 4
Anterior coil, dS HeadSpine coil, dStream, mDIXON, mra, Musculoskeletal, Peripheral MRA, Posterior coil, SENSE, Vascular
 

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