Method of unwrapping phase images in MRI used in radiology, involves calculating final difference image between calculated difference images of phase images, and calculating phase correction map using final difference image >>> Novelty The method involves acquiring three phase images at three different echo times following a single excitation with unequal echo time spacing. The difference images are calculated between two of the phase images. A final difference image between the calculated difference images is calculated. A phase correction map is generated from the final difference image. The phase correction map is added to one of the acquired phase images. >>> Use Method of unwrapping phase images in MRI used in radiology to visualize details of structures in patient's body, and to align magnetic spin of protons in water molecules body tissue. >>> Advantage The phase images with high contrast can be unwrapped quickly. The loss of information and deterioration of signal-to-noise ratio can be reduced.

1. UMPIRE - Unwrapping Multi- Tech Transfer
Echo Phase Images with Irregu- IP Consulting
IP Handling
lar Echo Spacings
Challenge
Most Magnetic Resonance Imaging (MRI) methods use the magnitude of the signal that is ac-
quired, and ignore complementary phase information. The phase of the MR signal is in fact very
sensitive to the local magnetic field, which reflects such clinically interesting properties as local
iron content. As a result, phase images allow veins and iron deposits in the brain to be imaged.
O F F E R
Phase effects are strongest at high magnetic fields and methods that use the phase of the MRI
signal have consequently grown in use in recent years along with the introduction of very high
magnetic field scanners (e.g. 7 Tesla). Phase images suffer from a unique ‘wrap’ artefact, how-
ever, which needs to be removed before the useful
contrast in the images can be clearly visualised. Cur-
rent ‘spatial’ unwrapping methods to do this are slow
and fragile while ‘temporal’ methods are restricted in
the range of phase wraps that can be removed.
Technology
The present technology is a temporal unwrapping
method capable of unwrapping heavily wrapped phase
images. It uses a number of images (from a ‘multi-
echo’ scan) with uneven spaces between the echoes.
For an example with 3 phase images (P1, P2, P3) ac-
T E C H N O L O G Y
quired at times TE1, TE2 and TE3 (see Figure). If the
time between P1 and P2 is ΔTE (=TE2-TE1), then the
time between P2 and P3 is chosen to be ΔTE+δTE,
where δTE denotes a small additional delay. The dif-
ference is calculated between the phase which evolves
between the first pair of echoes (PD1_2) and that be-
tween the second pair of echoes (PD2_3), then that
image (DPD in the Figure) is free of phase wraps if the
time δTE is chosen to be sufficiently short. The wrap-
free DPD image is used to identify wraps in phase dif- Figure: Steps in the method between the acquisi-
ference (PD) images and subsequently the original tion of wrapped images at three echo times (TE1,
phase images P1, P2 and P3. TE2 and TE3) and the calculation of unwrapped
images.
Technological Benefit
 Very fast compared to spatial methods
 More robust than spatial methods (does not need thresholds or seed voxels to be defined)
 Unwraps a much wider range of phase changes than other temporal methods
 Works where phase changes are rapid.
Development Status
 Applicability and functionality demonstrated
 prototype ready to be developed
Patent Status
WO2012/129585 A1 filed on January 5, 2012 (priority date: March 25, 2011)
Contact
Mathias Weiss
BDC – The Business Development Company GmbH
Pelikanweg 2 Phone: +41 61 270 88 04
CH-4054 Basel Mobile: +41 79 487 47 31
Switzerland Fax: +41 61 270 88 10
http://www.bdc-basel.com mathias.weiss@bdc-basel.com