Live out loud with Siemens Vibe.
The first hearing instrument that fits you, inside and out.

www.siemens.com/hearing

Why hide your vibe?
Youve never been afraid to stand out. So why choose a hearing instrument thats all about blending in? Siemens Vibe fits your personality and your ear in a radical new way. One that lets you connect with your Wild side. Or inner Superhero. Its about as far from ordinary as it gets. And thats the whole point.
It goes where no hearing instrument has gone before.
Bluetooth? MP3? Wireless headset? Guess again. Vibes design is so unique, it doesnt even look like a hearing instrument. Its the first one that fits securely into the crest of the ear. Your ear canal is left open, for greater comfort. And theres nothing behind your ear. So Vibe wont interfere with your eyeglasses or other devices. In fact, Vibes fit is so natural, youll forget its there. Until you hear what youve been missing.
It stays put because you dont.
With its totally new fit concept, Vibe is as simple as it is revolutionary. Wear it anywhere it will never slow you down. It stays secure, even when youre on the move. And with a simple push button control, its a snap to adjust. The fitting process is quick and easy too. Walk in and walk out with your Vibe. One visit is all it takes. Just tuck it in and go.
It fits who you are. At any given moment.
Like you, Vibe has nothing to hide. With an expanding selection of interchangeable, snap-on covers, you can show the world your true colors and change them just as fast as your mood. Whether you want to unmask your inner Flirt, rev up your Dynamo, or youre simply feeling Lucky, Vibe lets you express yourself any way you choose. So show your confidence. Spice up an outfit. Shake up the status quo. But never blend in.

Change is a good thing.

Vibe is all about keeping it fresh. With 19 totally hip colors and patterns to choose from, you can show your Vibe a different way every day. And well keep new designs coming. Because a little self-expression is a beautiful thing.

BABYDOLL

DYNAMO

PATTERNS

SOLIDS

SERIOUS

CHEEKY

GRANOLA

TRANSLUCENTS

INTENSE

FEARLESS

METALLICS

SUPERHERO
Its revolutionary from the inside out.
At Siemens, weve made a significant commitment to audiological research and development, enabling our hearing instruments to become the most advanced in the world. While each new technology represents another step forward, we also recognize that hearing instrument usability is just as important as the technology itself. Which is why Vibe not only comes equipped with cutting-edge technology, its also extremely simple to operate. In fact, Vibe is about as user-friendly as it gets.
Exclusive SoundSmoothing technology reduces annoying noises like rustling paper and clanging dishes, while preserving the sound of voices. The most effective transient noise reduction technology in the industry, SoundSmoothing ensures a much more comfortable listening experience. 8 channel digital signal processing for robust performance and flexibility to meet your unique needs. Vibes microphone is uniquely positioned to take advantage of the natural contours of your outer ear and the way it collects and funnels sound into the ear canal. FeedbackBlocker technology automatically reduces or eliminates annoying feedback (whistling) without affecting sound quality. Uses smallest 10A battery to minimize weight and size.

Whats your vibe?

No matter how you choose to face the world, you need to stay in touch. Vibe helps you do it with style. Siemens Vibe. Its time to live out loud.
The information in this document contains general descriptions of the technical options available, which do not always have to be present in individual cases and are subject to change without prior notice. The required features should therefore be specified in each individual case at the time of conclusion of the respective contract. 02.2008 Siemens AG Order No. A91SAT-00427-99C2-7600 Printed in Germany 104300/10055 02085. Siemens Audiologische Technik GmbH Gebbertstrasse Erlangen Germany Phone +308-0

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Please print clearly!

The Editorial Team
We appreciate your comments. Please contact us at magnetomworld.med@siemens.com
Antje Hellwich Associate Editor
Okan Ekinci, M.D. Center of Clinical Competence Cardiology, Erlangen, Germany
Peter Kreisler, Ph.D. Collaborations & Applications, Erlangen, Germany
Heike Weh, Clinical Data Manager, Erlangen, Germany
Bernhard Baden, Clinical Data Manager, Erlangen, Germany
Ignacio Vallines, Ph.D., Applications Manager, Erlangen, Germany
Wellesley Were MR Business Development Manager Australia and New Zealand
Milind Dhamankar, M.D. Sr. Director, MR Product Marketing, Malvern, USA
Michelle Kessler, US Installed Base Manager, Malvern, PA, USA
Gary R. McNeal, MS (BME) Advanced Application Specialist, Cardiovascular MR Imaging Hoffman Estates, USA
Dr. Sunil Kumar S.L. Senior Manager Applications, Canada
MAGNETOM Flash 3/2010 www.siemens.com/magnetom-world 3

Content

Tumor Staging

syngo SWI Case Reports

MSK Imaging at 3T
xxxxxSAR in pTx Spine Imaging Full
Further clinical information
Visit the MAGNETOM World Internet pages at www.siemens.com/ magnetom-world for further clinical information and talks by international experts.
Clinical Pediatric Imaging
6 MR Tumor Staging for Treatment Decision in case of Wilms Tumor G. Schneider, P. Fries 12 Cerebral Arterio-Venous Malformation detected by syngo TWIST MRA Ali Yusuf Oner, et al.

Patient history

A 4-year-old girl presented with a large palpable mass in the left upper quadrant and unspecific abdominal pain. Ultrasound had already revealed a large tumor of the left hemiabdomen with mass effect towards the liver. The patient was referred to our MRI department because of suspicion of Wilms tumor.

MRI protocol

MRI was conducted using a 1.5 Tesla MAGNETOM Aera with the combination of the 18-channel body coil and the integrated spine coil. For the MRI procedure the patient received an intravenous sedation using propofol. The imaging protocol included diffusion-weighted imaging (DWI, syngo REVEAL), acquired during free breathing, and transversal T2w TSE and HASTE sequences with navigator triggering. A single-shot echo planar diffusion imaging with Stejskal-Tanner diffusion encoding scheme was applied. For fat saturation, an inversion recovery technique was used. The sequence parameters were:
1 Transversal high-resolution T2w images showing the Wilms tumor (*) and multiple lung metastases (arrows). Due to the space occupying aspect of the large tumor, the residual kidney is swollen (+) and also slight edema of the liver hilum can be seen (arrowheads).

Continued on page 10

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2 Rotating MIP based on high b-value images.

5C 3A 3B 3C 3D

3 (A) Coronal DWI MIP. Original b-value images at 0 and 800 s/mm2 (B, C and E, F) as well as calculated b-value at b 1400 s/mm2 (D, G) are shown. (Arrows pointing to lung metastases.)
5 Based on ADC maps and high b-value images (b 1400 s/mm2 is shown), a clear differentiation between residual but swollen kidney tissue (arrows) and the Wilms tumor (arrowhead) is possible. Both types of tissue differ in their cellular density, however, on T2w images no clear differentiation is possible in this case (compare Fig. 1). Nevertheless, not all areas of the tumor are characterized by high signal on the very high b-value images, demonstrating well the tumor heterogeneity. (A, B) ADC maps. (C, D, E) b 1400 s/mm2 images. (F) Coronal thick-slice MPR based on b 1400 s/mm2 images (* spleen).

Note the three separate FOV boxes. The upper FOV is yellow, indicating that it is currently active. By utilising coupled graphics you can grab and drag all of the three and move them as one. This makes setting up your coverage very easy. Each FOV is also numbered and you can select them by clicking on the little numbers.
By having a sagittal localizer in this box you can keep an eye on your FOV.

T-Spine

Once you are happy with the C-Spine slice group location you can move on to the T-Spine. Again to set this up follow the same systematic approach. Load a sagittal and coronal T-Spine localizer image into the square windows.
Keep the Full Spine coronal image in the rectangular window. To select the thoracic spine subgroup click on the small number 2 displayed next to the second subgroup. You will know you have the group selected as it will turn yellow.
With coupled graphics off you can now proceed to angle the slice group to follow the thoracic spine. You will note that there is some overlap between groups 1 and 2 this is needed for the composing process later on.
Using the coronal localizer in these boxes lets you locate your slice group and angle appropriately. With coupled graphics off, the changes you make only affect this individual slice group.
Easy FOV set up to cover the whole spine.
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L-Spine

Performing your axial scanning
Once you are happy with the T-Spine slice group location you can move on to the L-Spine. Again to set this up follow the same systematic approach. Load a sagittal and coronal L-Spine localizer image into the square windows.
Keep the full spine coronal image in the rectangular window. To select the lumbar spine subgroup click on the small number 3 displayed next to the third subgroup. You will know you have the group selected as it will turn yellow.
With coupled graphics off you can now proceed to angle the slice group to follow the lumbar spine. You will note that there is some overlap between groups 2 and 3 this is needed for the composing process later on.

You can see how each subgroup for the T2 sagittals has its own number: 2.1, 2.2, 2.3 etc. Thus if you need to rerun a region simply hold shift and click the one you need to repeat. Drag and drop that region back into the queue. A cross will run through the compose indicator, showing that it is only going to run that one region again.
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Initially your composed images will look like those opposite. We run a normalize filter across the images which helps to smooth out the signal and stitching points.
Once the images have been normalized you need to save the entire series, thus select Save all As as shown. Give the sequence a name such as T2 SAG Compose, etc. Ensure you save them as a new series. Repeat the process for the other sagittal contrast weightings.
The saved series will appear in the browser and you can then send it to viewing and film it. The initial compose images are highlighted in blue (long red arrow) with our saved series appearing at the bottom of the list (short red arrow). Your composed series can be sent to PACS from here also.
Contact James Hancock Benson Radiology Adelaide South Australia James.Hancock@bensonradiology.com.au
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Knee Imaging with 4-Channel Flex Coils. The Inuence of Patient Positioning and Coil Selection on Image Quality
Birgit Hasselberg; Marion Hellinger Siemens Healthcare, Erlangen, Germany
Done right, the patient is again positioned supine on the table in feet first orientation. However, in this case the left knee is raised by a cushion in order to avoid the aliasing effect. The knee which is not examined is positioned higher than the examined knee. The resulting transversal image shows no aliasing effects.
Correct patient positioning and the selection of the right coil have a huge influence on image quality as the following examples clearly show. The patient is positioned supine on the table in feet-first orientation. In the first case, the patient lies straight on the table; both knees are positioned in one plane. The resulting transversal clinical image shows aliasing effects from the left knee (which is not being examined) in the left-right phase-encoding direction.
4 Patient correctly positioned for knee exam. The knee not being examined is positioned on a cushion.
Patient positioned for an examination of the right knee. Both knees are positioned in one plane.

4-Channel Flex coil large and small
Finally, remember to position the patient in the isocenter of the magnet. The flexibility of the large and small 4-channel flex coils gives perfect support in optimal left-right positioning. As shown above, the 4-channel flex coils come in 2 sizes and are part of the standard system configuration. They provide superior signal-to-noise-ratio (SNR) and can be used for the examination of various body parts. The wrap
around coil is made of soft and flexible material. Due to its 4-channel design it is iPAT-compatible. The coil can easily be combined with other coils such as Spine 32 and Body 18. In summary, we can state that in knee examinations correct patient positioning and the selection of the right coil have a huge influence on the resulting clinical images.
Contact Marion Hellinger Siemens Healthcare H IM MR PLM AW T Workflow Allee am Roethelheimpark 2 D-91052 Erlangen Germany marion.hellinger@siemens.com
In daily patient-care imaging of joints in childhood is often still a domain of x-ray and ultrasound. However, the application of MRI in pediatric imaging is of growing importance not only because of the excellent soft tissue contrast and the superior capacity of this technique to visualize and evaluate the extension of involvement of soft tissues but also because of its capability to early and precisely detect bone destruction. In addition to its high sensitivity, MRI is

k Get free-of-charge

application training at www.siemens.com/ magnetom-world In this 8 min online training on fat saturation you will learn how to identify the fat and water peaks to calculate fat and water separation to perform the optimal fat saturation process www.usa.siemens.com/ fatsat-video
1 Conventional x-ray of the left knee (same examination date as MRI) with subchondral erosion of both femor condyles and thinning of the lateral joint space.

k Visit us at

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factor of 2, bandwidth 280 Hz/px, no averaging, TA 3:41 min). Transversal PDw TSE with spectral fat saturation (TR 3420 ms, TE 77 ms, FOV (197 x 220) mm2, matrix (804 x 896, interpolated) px2, slice thickness 4 mm, parallel imaging factor of 2, bandwidth 162 Hz/px, no averaging, TA 2:38 min). Coronal native T1w SE without fat saturation (TR 872 ms, TE 11 ms, FOV (165 x 220) mm2, matrix (384 x 512) px2, slice thickness 3 mm, no parallel imaging, bandwidth 150 Hz/px, no averaging, TA 3:19 min). Transversal enhanced T1w TSE without fat saturation (TR 458 ms, TE 12 ms, FOV (194 x 220) mm2, matrix (396 x 448) px2, slice thickness 4 mm, parallel imaging factor of 2, bandwidth 180 Hz/px, two averages, TA 5:30 min). Coronal enhanced T1w TSE with spectral fat saturation (TR 1210 ms. TE 13 ms, FOV (165 x 220) mm2, matrix (326 x 512) px2, slice thickness 3 mm, parallel imaging factor of 3, bandwidth 181 Hz/px, no averaging, TA 2:50 min). Total imaging time was approximately 25 minutes.

1 Patient with contractions of the lower extremities. MR-compatible wheelchair for easy patient transport.

Case 1

As a center dealing with a high number of patients with hemi-/ paraplegia, cerebral palsy as well as scoliosis, the 70 cm open-bore system has the advantage of a very flexible patient positioning. As demonstrated in figure 1B, especially severe contractions of the extremities often seen in these patients do require sufficient space in the anterior-posterior direction. In figure 1A our MR-compatible wheelchair is shown, which enables an easy and relative fast patient transport into the scanner.
Flexible patient positioning in the 70 cm open-bore system.
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Clinical Cardiovascular

Orthopedic Imgaging Clinical
2 A) T1w TSE sagittal B) T2w TSE sagittal

Case 3

In case of malignancies or inflammation, however, we have to expand our clinical routine protocol. This case shows selected images of a 63-year-old male patient with known spinal astrocytoma WHO grade III. This patient underwent chemo- and radiotherapy and presented at our institution with clinically stable paraplegia at the level of Th5. A swollen myelon can be seen in this follow-up exam at the height of the irradiated tumor at the height of thoracic vertebra 68. On post-contrast T1w MRI, an inhomogeneous medullar enhancement can be seen (arrow). Note that the patient also underwent laminectomy and that a residual seroma can be detected. Enhancement within the vertebra was stable over a long period of time and based also on CT imaging, this finding has to be classified as a hemangioma of the 9th thoracic vertebra.
C) T1w TSE axial (oblique) D) T2w TSE axial (oblique)
3 A) T1w TSE sagittal B) T2w TSE sagittal C) ce T1w sagittal with fat-saturation D) ce T1w axial (oblique)

Case 2

This case demonstrates our standard imaging strategy in case of lower back pain. We apply mainly turbo spin-echo (TSE) sequences for this purpose. Sequence parameters for the shown images are: T1w TSE sagittal: resolution (0.7 x 0.7 x 3.0) mm3, TR 684 ms, TE 12 ms, TA 2:48 min (fig. 2A). T2w TSE sagittal: resolution (0.7 x 0.7 x 3.0) mm3, TR 3650 ms, TE 113 ms, TA 3:00 min (fig. 2B). T1w TSE axial (oblique): resolution (0.7 x 0.7 x 3.0) mm3, TR 969 ms, TE 12 ms, TA 3:09 min (fig. 2C). T2w TSE axial (oblique): resolution (0.7 x 0.7 x 4.0) mm3, TR 5060, TE 115 ms, TA 2:59 min (fig. 2D). With a total scan time of less than 15 minutes, this protocol focuses on a fast assessment of the lumbar spine. However, because of the higher signal-tonoise contribution of the 3 Tesla system in combination with the integrated multi-channel spine coil, also a relatively high sub-millimeter in-plane resolution at slice thicknesses of 3 mm for sagittal and transversal planes is achieved. In this particular case, a medio-lateral large hernia of the intervertebral disc of L5/S1 with compression of the left nerve root is seen (arrows).

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Case 4

43-year-old male patient, who underwent a dorsal stabilization after traumatic fracture of vertebra Th10 and had complete paraplegia below this segment. On conventional x-ray, the spine fusion from Th9 to Th11 is shown (fig. 4A). Figure 4B shows an MRI which was performed at our institution with our old 1 Tesla scanner. While artifacts caused by metallic implants on the 1T exam with the chosen sequences are less prominent compared to imaging at 3T (compare Fig. 4C), SNR and therefore in-plane resolution was low in the 1T exam and a further evaluation of the tethering of the myelon was not possible. The high SNR of the 3T scan allowed for a high in-plane resolution (Fig. 4C, D) and also for T2w 3D imaging (syngo SPACE, Fig. 4E).The capability of evaluating the whole area of interest with the SPACE sequence at highest resolution and contrast in any orientation allowed further evaluation of the reason for the dorsal dislocation of the myelon starting at the height of Th6. Based on this MRI exam, the suspicion of an arachnoidal cyst was supported leading to a dorsal dislocation and compression of the myelon. Even the slight arachnoidal web could be detected on the SPACE sequence (red arrow in Fig. 4D). Slice thickness for sagittal T2w images were 3 mm for both examinations at 1 and 3 Tesla, respectively. Resolution of the syngo SPACE exam was (0.7 x 0.7 x 0.7) mm3.

Case 5

66-year-old female patient with molecular pathology confirmed Ewing sarcoma of the right humerus. After initial tumor excision in 2009 and osteosynthesis, the patient presented with an extensive recurrence of the tumor within four months. Figure 5A demonstrates the large tumor with infiltration also of the bone marrow. In addition, diffuse oedema is shown (arrowhead in 5A). Figure 5B also shows a large lymph node metastasis (arrow). Therefore, before again operating on the humerus, the orthopaedic tumor surgeon wants to know whether more lesions are present. Thus, a whole-body scan was added (Fig. 5C), demonstrating also multiple osseous filiae (arrows in 5C) of the pelvis and spine. No evidence of high risk or presence of a pathologic fracture was found. By selecting appropriate imaging techniques, imaging at 3T even with metal implants present and off-center positioning can result in excellent image quality. The achievable superior resolution clearly increases confidence about extension of a tumor and impairment of anatomical structures. In addition, the capability of scanning large areas of interest up to whole-body without compromise in image quality and within a clinical acceptable setting (time and patient-comfort wise) is a prerequisite for any sufficient oncologic decision making and is highly esteemed by our tumor surgeons, especially to detect skip lesions that would distinctly influence the therapeutic concept. The superior capability of evaluating changes within the bone marrow including diffuse tumor infiltration is a particularly big advantage in our patient cohort.

5 A) Coronal ce T1w with fat saturation.
B) Axial ce T1w with fat saturation.
C) Coronal T2w whole-body with fat saturation.
4 A) Conventional x-ray B) T2w sagittal at 1T C) T2w sagittal at 3T D) T2w syngo SPACE at 3T
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6 A) Conven-

tional x-ray B) T2w sagittal at 1T
C) T2w sagittal at 3T D) T2w syngo SPACE at 3T
7 A) T2w sagittal at 3T B) T1w sagittal at 3T C) T2w sagittal at 1T

Case 6

Complex congenital malformation of the central nervous system, as well as the spine, requires also evaluation of the whole systemic aspect of disease. In this case, we show images from a 15-year-old boy with Arnold Chiari II malformation and lumbal meningomyelocele (closed by surgery after birth). Because of severe and progedient complex scoliosis, this patient also underwent a dorsal spine fusion of Th9 downwards to the pelvis with VEPTR instruments and underwent multiple extensions (conventional x-ray Fig. 6A). Figures 6B and C do show the image quality difference between 1 and 3T exam (both 3 mm slice thickness). Again, the superior SNR and in-plane resolution allows for a more detailed assessment of the meningomyelocele (arrows). Especially T2w 3D imaging allows for a detailed assessment of all aspects of the impairment of the central nervous system including the myelon and nerve roots. Figure 6D shows the results of a syngo SPACE exam of the whole spine. The meningomyelocele is resolved in detail (arrow) as well as the displacement of the cerebellum as part of the Arnold Chiari malformation. Also tethering of the myelon, which is important for the orthopaedic surgeons to know about because it must be resolved before any operation to the spine, is well depicted. Note also the displacement of inner organs in this case (asterisk marks one of the kidneys).

Case 7

Exam of a 59-year-old male patient with complete tetraplagia at the level of C5 and secondary syringobulbia starting at the vermis down to the 6th thoracic vertebra as a consequence of a bathing accident in 1968. The patient received arachnolysis and dural plastic as specific therapy, as well as a wound examination because of a liquor pad. The syngo SPACE exam (Fig. 7A) shows multiple horizontal septae, which divide the syrinx and might hinder CSF exchange and thus might cause extension of the syrinx. The 3 Tesla T2-weighted image (Fig. 7A) better delineates the septae than the 1 Tesla T2-weighted image (Fig. 7C). In this case, a complete suppression of the liquor was seen on FLAIR images (not shown), suggesting communication of the multiple cystic lesions and the subarachnoid space.

robust procedure in the clinical workflow. In addition, several consulting radiologists requested that this functionality should be available as an inline tool; the implementation of a liver registration based on dedicated postprocessing software would have limited its wide clinical usage. Independent from this request, however, retrospective non-rigid registration of dynamic data is required for multiple purposes and already implemented for advanced image reading software. The non-rigid registration of a fourphase liver DCE MRI exam (syngo dynaVIBE) is already available for all MR scanners equipped with the software versions syngo MR B 15 and 17. As described in Non Rigid 3D-Registration for Accurate Subtraction of Dynamic Liver Images for Improved Visualization of Liver Lesions with syngo dynaVIBE on page 71 of this issue, these implementations of syngo dynaVIBE require that the liver DCE MRI is set up as one single sequence with four measurements (covering the four liver phases: native, arterial, (portal-)venous and late (or equilibrium) phase). While this approach assures perfect match and correct assignment of the different phases for the correction algorithm, in clinical routine a more flexible handling may be required e.g. one could apply a single-shot HASTE MRCP between the (portal-) venous and late phase.
References 1 Van den Bos IC, Hussain SM, Dwarkasing RS, Hop WC, Zondervan PE, de Man RA, IJzermans JN, Walker CW, Krestin GP. MR imaging of hepatocellular carcinoma: relationship between lesion size and imaging findings, including signal intensity and dynamic enhancement patterns. J Magn Reson Imaging. 2007 Dec;26(6):1548-55. 2 Van den Bos IC, Hussain SM, Terkivatan T, Zondervan PE, de Man RA. Stepwise carcinogenesis of hepatocellular carcinoma in the cirrhotic liver: demonstration on serial MR imaging. J Magn Reson Imaging. 2006 Nov;24(5):1071-80. 3 Terkivatan T, van den Bos IC, Hussain SM, Wielopolski PA, de Man RA, IJzermans JN. Focal nodular hyperplasia: lesion characteristics on state-of-the-art MRI including dynamic gadolinium-enhanced and superparamagnetic iron-oxide-uptake sequences in a prospective study. J Magn Reson Imaging. 2006 Oct;24(4):864-72. 4 Yu JS, Chung JJ, Kim JH, Kim KW. Hypervascular focus in the nonhypervascular nodule (nodulein-nodule) on dynamic computed tomography: imaging evidence of aggressive progression in hepatocellular carcinoma. J Comput Assist Tomogr. 2009 Jan-Feb;33(1):131-5. 5 Yu JS, Kim YH, Rofsky NM. Dynamic subtraction magnetic resonance imaging of cirrhotic liver: assessment of high signal intensity lesions on nonenhanced T1-weighted images. J Comput Assist Tomogr. 2005 Jan-Feb;29(1):51-8. 6 Hecht EM, Holland AE, Israel GM, Hahn WY, Kim DC, West AB, Babb JS, Taouli B, Lee VS, Krinsky GA. Hepatocellular carcinoma in the cirrhotic liver: gadolinium-enhanced 3D T1-weighted MR imaging as a stand-alone sequence for diagnosis. Radiology. 2006 May;239(2):438-47. 7 Holland AE, Hecht EM, Hahn WY, Kim DC, Babb JS, Lee VS, West AB, Krinsky GA. Importance of small (< or = 20-mm) enhancing lesions seen only during the hepatic arterial phase at MR imaging of the cirrhotic liver: evaluation and comparison with whole explanted liver. Radiology. 2005 Dec;237(3):938-44. 8 Chefdhotel C, Hermosillo G, Faugeras O Flow of Diffeomorphisms for Multimodal Image Registration Proc IEEE Int S Bio Im, 2002.

Non Rigid 3D-Registration for Accurate Subtraction of Dynamic Liver Images for Improved Visualization of Liver Lesions with syngo dynaVIBE
Matthias P. Lichy, M.D.; Wilhelm Horger; Berthold Kiefer, Ph.D. Siemens Healthcare, Magnetic Resonance, Erlangen, Germany
The arterial phase derived from T1w contrast-enhanced liver dynamics (liver DCE) is perhaps one of the most important diagnostic tools for the assessment of liver disease. However, true enhancement of liver lesions is hard to judge in several conditions such as liver fibroses or tumor necroses. In addition, even under optimal conditions, the patient might hold his breath in slightly different respiratory phases during the multiple breathholds of a multi-phase DCE liver exam (native, arterial, portalvenous and equilibrium phase) which can result in a clear offset of the anatomical position over the different phases. This has disadvantages for the reading of liver DCE data: firstly, the position has to be aligned manually (in the worst case three out of the four data sets) and secondly, the subtraction of different phases will generate severe artifacts and may falsely hint to an enhancement. But for a precise anatomical alignment it is also insufficient to adjust just the mismatch over time for the liver in the craniocaudal direction; under certain conditions e.g. severe ascites or liver resection, movement within the plane including deformation of the tissue can also be observed. With syngo dynaVIBE, however, it is easy to set up liver DCE scans with retrospective non-rigid registration of the different liver phases (Figure 1) and also to generate subtracted images which can be used for improved demonstration of contrast-enhancement of the different phases without the need of
*See also Eric Hatfield et al. Revisiting liver imaging with VIBE in MAGNETOM Flash #39, 2/2008 available online at www.siemens.com/magnetom-world Further reading: Diego R. Martin et al. Challenges and clinical value of automated and patient-specific dynamically timed contrast-enhanced liver MRI examination in MAGNETOM Flash #42, 3/2009 available online at www.siemens.com/magnetom-world
Contact Ulrich Kramer, M.D. Diagnostic and Interventional Radiology University Hospital Tbingen Hoppe-Seyler-Str. Tbingen Germany Ulrich.Kramer@med.uni-tuebingen.de

1 Scheme of the functionality of a non-rigid liver registration. In general, a dynamic liver scan consists of four phases (native (row I), arterial (row II), venous (row III) and equilibrium, row IV)). Colum A displays the original results from such a MR exam. However, an anatomical mismatch between the different phases can be observed (reference scan is shown in light grey). The dynaVIBE algorithm analyses the deformation of the tissue in all three dimensions and performs an elastic correction of the voxel shift (columns B and C). Resulting (column D) is an exact match of the anatomical structures over space and time allowing a voxelbased analysis of the liver.
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2 Easy set up of syngo dynaVIBE.
3 Example of an insufficient match between two phases (A and B) of a dynamic liver scan at identical z-axis position. In this example, no contrast-media was applied. A subtraction of two completely identical data sets would therefore result in a black screen. 3C shows how a simple subtraction of these two data sets results in severe artifacts, either artificial enhancement (arrows) or signal void (asterisk). After applying the liver registration algorithm, a nearly perfect subtraction is achieved. However, this does not compensate for signal intensity changes introduced e.g. by pulsation / movement within one acquisition (arrows) or non contrast-media related signal changes as present in this example within the aorta (asterisk).
further post-processing steps. This technology is available for all MAGNETOM systems running on syngo MR B15, 17 and for the syngo MR D software versions.
How to set up a syngo dynaVIBE liver DCE
A syngo dynaVIBE liver DCE examination requires four phases: a) Native b) Arterial c) (Portal-) Venous d) Equilibrium phase. As MR sequence, a T1w 3D VIBE with fat
saturation is used. It is important for the Inline calculation of the non-rigid liver registration and for the subtraction of the different phases that the scanner can clearly identify the coherent measurements which define the liver DCE. It is also a prerequisite for the algorithm that the number of slices within the slab, FOV and matrix are not changed for the separate phases of a liver DCE exam. Therefore all the above four measurements must be linked. This can easily be achieved by selecting multiple measurements in the Inline menu when adjusting the 3D VIBE sequence
parameters. This parameter has to be set to 4. By activating the Liver registration feature (simply check the box, cf. figure 2), the non-rigid liver registration will be performed after the completion of the liver DCE. By default, the second phase (which should represent the arterial phase) will be used as reference for the liver registration and the other three measurements will be adjusted accordingly to the position and shape of the liver as present in the reference phase. Based on this registration one can easily generate subtracted images by simply

Reconstruction with Projection Onto Convex Sets (POCS)
A new option to enhance image reconstruction is also available in the syngo MR B17 software: Projection Onto Convex Sets or POCS can be selected on the Resolution Filter UI tab card when using partial Fourier in the phase and/or read directions. POCS reconstruction will sharpen the image by reducing the blurring induced by partial Fourier acquisition.
Volume Interpolated Breathhold Examination (VIBE) [1] is a well known technique for imaging of the liver. VIBE offers three-dimensional multi-phase acquisition before and following contrast administration under breathhold conditions. The dynamic behavior of the liver lesions and structures is typically analyzed by scanning pre-contrast,
arterial, portal venous, early equilibrium and 5 minutes delayed equilibrium phases of enhancement. This allows more accurate characterization than static pre or post-contrast analysis. In the syngo MR B17 software, new functionalities have been added to the VIBE sequence to better meet the clinical requirements. The following are
the most critical requirements for VIBE: uniform fat suppression, excellent tissue contrast, image sharpness, few artifacts, and short scan time. The new functionalities include a new k-space reordering scheme, a new fat suppression scheme, and a new reconstruction functionality.

1 The linear

reordering scheme as seen in the user interface (UI).
2 The POCS option as it appears on the resolution tab.
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3 Typical VIBE

images obtained at 3T MAGNETOM Trio, A Tim system (A) Arterial phase.
3 (B) Portal venous phase. (Images courtesy of Washington University in St Louis.)

Examples of protocols

The followings are recommendations to acquire good image quality of VIBE for liver imaging: Q-Fatsat with linear reordering. 320 base resolution to increase image sharpness.
10 degree excitation flip angle at 1.5T system and 9 degree at 3T system for uniform fat suppression. Symmetric echo for image sharpness. Opposed phase TE if using asymmetric echo for uniform fat suppression. Slice partial Fourier = 6/8.
Phase partial Fourier = Off for image sharpness. If further scan time reduction is necessary, select 7/8 phase partial Fourier. Using POCS will reduce blurring. Prescan Normalize filter.
Figure 3 shows the typical image quality of the arterial phase (A) and the portal venous phase (B) acquired at 3T MAGNETOM Trio Tim with the following parameters: Q-Fatsat with linear reordering, BW 446 Hz/pixel, base resolution 320, slice thickness 3 mm, echo
asymmetry Off, phase partial Fourier Off, TE 1.9 ms, TR 4.1 ms, 72 partitions, Prescan normalized, total acquisition time 19.72 seconds. These images show good fat suppression and good contrast enhancement.

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4 A portal venous

phase as seen in a patient with colorectal cancer metastasis obtained at 3T MAGNETOM Trio with Tim system. (Images courtesy of Washington University in St Louis.)

Pre-contrast

Arterial phase

Portal venous phase

Early equilibrium
5 Dynamic contrast-enhanced images of a patient with metastases from a colon cancer obtained at 1.5T open-bore MAGNETOM Espree system. (Images courtesy of Washington University in St Louis.)

Conclusions

Figure 4 shows another example of clinical cases obtained from 3T MAGNETOM Trio, A Tim system. Images shown are the portal venous phase of a patient with metastases from a colon cancer obtained with the same 3T protocol mentioned above. Image sharpness and contrast enhancement are seen in this example. Figure 5 is an example of a multi-phase contrast-enhanced VIBE scan on a 1.5T open-bore MAGNETOM Espree system of a patient with metastases from colon cancer with the following protocol: Q-Fatsat with linear reordering, BW 390 Hz/pixel, Base resolution 320, slice thickness 3 mm, echo asymmetry Off, phase partial Fourier Off, TE 2.2 ms, TR 4.4 ms, 72 partitions, acquisition time 24 seconds. These images show sharpness, good contrast enhancement, uniform fat suppression and reduced artifacts on an open-bore system. New functionality of the VIBE sequence in the syngo MR B17 software allows improvements in fat suppression, tissue contrast, image sharpness, residual artifact, and scan time. The improvements in image quality are shown on both 3T and 1.5T systems.

5 min delay

References 1 Rofsky NM, Lee VS, et al. Abdominal MR Imaging with a Volume Interpolated Breath-hold Examination. Radiology. 1999 Sept; 212(3):876-84.
Contact Agus Priatna Siemens Medical Solutions USA, Inc. MR Research Collaborations 51 Valley Stream Parkway Malvern, PA 19355-1406 USA agus.priatna@siemens.com