ISMRM 24th Annual Meeting & Exhibition • 07-13 May 2016 • Singapore

Scientific Session: Whole Body/PET/MRI

Thursday Thursday, May 12, 2016
Summit 2
10:30 - 12:30
Moderators: Peder Larson, Alan McMillan

Improvement in Alignment & Signal Uniformity via Realtime B0 Correction and Image Registration in Multi-station PET/MR Whole body Diffusion Imaging - Video Not Available
Maggie Mei Kei Fung1, Abhishek Sharma2, Justin Lahrman3, Lloyd Estkowski4, and Ersin Bayram5
1MR Apps & Workflow, GE Healthcare, New York, NY, United States, 2MR Engineering, GE Healthcare, Bangalore, India, 3MR Apps & Workflow, GE Healthcare, Waukesha, WI, United States, 4MR Apps & Workflow, GE Healthcare, Menlo Park, CA, United States, 5MR Apps & Workflow, GE Healthcare, Houston, TX, United States
In a PET/MR imaging, anatomical alignment between PET & MR images and good visualization of spine & lymph node are critical in the clinical interpretation of diseases. In whole body multi-station diffusion weighted imaging (DWI), it is common to observe signal drop off and spatial misalignment due to B0 inhomogeneity. In this study, we proposed a two-prong approach in improving the signal uniformity & spatial alignment by combining a real-time slice-by-slice B0 correction technique and an image registration technique. We have validated the approach in 18 volunteers with various physical attributes. 

Diagnostic ability of Whole-Body Diffusion-Weighted Imaging in malignant tumors compared with PET-CT
Xiaoyi Wang1, Ning Wu1, Yanfeng Zhao1, Han Ouyang1, Lizhi Xie2, Jin Zhang1, Li Liu1, Wenjie Zhang1, Rong Zheng1, Ying Liang1, and Ying Liu1
1Department of Diagnostic Imaging, PET-CT Center, Cancer Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing,China, Beijing, China, People's Republic of, 2GE Healthcare China, Beijing, China, Beijing, China, People's Republic of
Because of its convenience in whole body examination, whole body MRI is growing popular, especially in the tumor diagnosis. In the present work, the diagnostic ability of whole-body diffusion-weighted imaging  in malignant lesions is compared with that obtained with 18F-FDG PET-CT. We found that WBDWI was an effective method for screening bone metastasis, especially suitable for radiation-vonuerable population, and it is better than PET-CT in detecting low grade malignant tumor.  In summary, WBDWI can be used as a potential alternative to PET/CT in addition to conventional MR examination.

PET/MR attenuation correction using Zero Echo Time imaging in 15O-water study - Permission Withheld
Mohammad Mehdi Khalighi1, Gaspar Delso2, Praveen K. Gulaka3, Audrey Peiwen Fan3, Bin Shen4, Aileen Hoehne4, Prachi Singh3, Jun-Hyung Park4, Dawn Holley3, Frederick T. Chin3,4, and Greg Zaharchuk3,4
1Applied Science Lab, GE Healthcare, Menlo Park, CA, United States, 2Applied Science Lab, GE Healthcare, Zurich, Switzerland, 3Radiology Department, Stanford University, Stanford, CA, United States, 4Molecular Imaging Program, Stanford University, Stanford, CA, United States
Accurate identification of bone tissue is important to generate attenuation correction maps on a PET/MR scanner for quantification of tracer activity in PET images. Head atlas-based attenuation correction and a new zero echo time technique (ZTE) for attenuation correction are compared in an 15O-water brain study. The comparison shows that ZTE-based attenuation correction provides more accurate identification of bone tissue and thus of the tracer activity. Any mismatch in bone identification will affect the tracer activity, especially in voxels close to the bone.

Respiratory Resolved Attenuation Correction Maps for Motion Compensated PET-MR using Dixon-GRPE
Christoph Kolbitsch1,2, Radhouene Neji3, Matthias Fenchel4, and Tobias Schaeffter1,2
1Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom, 2Physikalisch-Technische Bundesanstalt (PTB), Braunschweig and Berlin, Germany, 3MR Research Collaborations, Siemens Healthcare, Frimley, United Kingdom, 4MR Oncology Application Development, Siemens Healthcare, Erlangen, Germany
Quantitative PET requires accurate attenuation correction (AC) information. For simultaneous PET-MR acquisitions in the thorax or abdomen these MRAC images are obtained in a single breathhold which can lead to misregistration errors between breathhold MRAC and free-breathing PET data. Here we present a method which obtains accurate AC information (Dice coefficient higher than 0.85) during free-breathing and yields additional respiratory motion fields which can be utilised in motion-compensated MR and PET reconstructions. The proposed Dixon-GRPE method led to improvements of up to 50% in sharpness (FWHM) and a 33% improvement in the quantification of the specific uptake value (SUV).

Impact of MR-based PET motion correction on the quantification of myocardial blood flow: an in-vivo simultaneous MR/PET study
Yoann Petibon1, Behzad Ebrahimi1, Timothy G Reese1,2, Nicolas Guehl1, Marc D Normandin1, Nathaniel M Alpert1, Georges El Fakhri1, and Jinsong Ouyang1
1Center for Advanced Medical Imaging Sciences, Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States, 2Athinoula A. Martinos Center, Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
Dynamic PET imaging enables absolute quantification of myocardial blood flow (MBF). However, motion of the heart during imaging deteriorates the accuracy of PET MBF measurements. Simultaneous MR/PET makes it possible to compensate PET images for motion by incorporating MR-based motion information inside the PET reconstruction process. In this study, we propose and assess the impact of a tagged-MRI based PET motion-correction technique for improved PET MBF quantification using an in-vivo simultaneous MR/PET study.

Efficient 5D imaging of thorax and abdomen for MR-guided PET motion correction
Christian Würslin1, Dominik Fleischmann2, and Roland Bammer1
1Radiological Sciences Laboratory, Stanford University, Stanford, CA, United States, 2Cardiovascular Imaging Section, Department of Radiology, Stanford University, Stanford, CA, United States
Cardiac imaging under free breathing is a desirable tool for clinical routine, which can provide improved patient comfort and shorter examination times. Furthermore, it can be used in the context of MR-guided PET motion correction in simultaneous PET-MRI. Here, we propose a radial acquisition and reconstruction framework for the acquisition of these images. A piecewise rigid respiration motion model enables a highly efficient use of the acquired data to either achieve higher image quality or shorter examination times than standard, dual-gated techniques.

MR-PET simultaneous acquisitions with attenuation correction using LSO background radiation.
Liliana Lourenco Caldeira1, Theodoros Kaltsas1, Jürgen Scheins1, Elena Rota Kops1, Lutz Tellmann1, Uwe Pietrzyk1, Christoph Lerche1, and N. Jon Shah1,2
1Institute of Neuroscience and Medicine, Forschungszentrum Jülich, Jülich, Germany, 2Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany
In this work, the goal is to perform attenuation correction (AC) for MR-PET scanners using the background activity from LSO (Cerium-doped Lutetium Oxyorthosilicate) scintillator used in PET scanners. This approach has the advantage of obtaining a geometrically aligned AC map with the PET emission scans, which can be useful for coil AC maps. We demonstrate our approach for the Siemens 3T MR-BrainPET with a Tx/Rx 8-channel head coil and a 3-rod phantom. 

[18F]FDG PET/MRI Of Patients With Chronic Pain Alters Management: Early Experience.
Daehyun Yoon1, Deepak Behera1, Dawn Holley1, Pamela Gallant1, Ma Agnes Martinez Ith2, Ian Carroll3, Matthew Smuck2, Brian Hargreaves1, and Sandip Biswal1
1Radiology, Stanford University, Palo Alto, CA, United States, 2Orthopaedic Surgery, Stanford University, Palo Alto, CA, United States, 3Anesthesia, Stanford University, Palo Alto, CA, United States
The chronic pain sufferer is currently faced with a lack of objective tools to identify the source of their pain. Increased inflammation of the nervous system, vessels, muscles, and other tissues in chronic pain sufferers and [18F]fluorodeoxyglucose positron emission tomography/magnetic resonance imaging ([18F]FDG PET/MRI) has emerged as a sensitive clinical tool to identify increased inflammation. We plan to develop clinical [18F]FDG PET/MRI method to more accurately localize sites of hypermetabolic foci as it relates to pain generators.  Early clinical results suggest that [18F]FDG PET/MRI can identify abnormalities in chronic pain patients and can immediately affect their management.

Distribution and metabolism of 89Zr-labeled HDL nanoparticles in atherosclerotic rabbits: in vivo, longitudinal imaging with PET/MRI
Claudia Calcagno1,2, Carlos Perez-Medina1,2, Tina Binderup3, Mark E Lobatto4, Seigo Ishino1,2, Mootaz Eldib1,2, Philip Robson1,2, Sarayu Ramachandran1,2, Thomas Reiner5, Edward Fisher6, Zahi A Fayad1,2, and Willem JM Mulder1,2
1Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States, 2Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States, 3University of Copenaghen, Copenaghen, Denmark, 4Academisch Medisch Centrum, Amsterdam, Netherlands, 5Memorial Sloan Kettering Cancer Center, New York, NY, United States, 6New York University School of Medicine, New York, NY, United States
Abundant, active inflammatory cells are a hallmark of high-risk atherosclerotic plaques. High-density lipoprotein (HDL) is a natural nanoparticle composed of phospholipids, cholesterol and apolipoprotein A-I (APOA1), which has been shown to have atheroprotective properties.  . The recent development of combined PET/MRI scanners and new advances in radio-labeling technology gives the opportunity to investigate theese properties in vivo. Using a unique set-up combining PET/CT and PET/MRI, we non-invasively assess the pharmacokinetics, distribution, metabolism and turnover of 89Zr-HDL’s in a rabbit model of atherosclerosis.  

PET/MRI in Pancreatic and Periampullary Cancer: Correlating Diffusion-weighted Imaging, MR spectroscopy, and Glucose Metabolic Activity With Clinical Stage
Bang-Bin Chen1, Yu-Wen Tien2, Ming-Chu Chang3, Mei-Fang Cheng4, Yu-Ting Chang3, Chih-Horng Wu1, Xin-Jia Chen1, Ting-Chun Kuo2, Shih-Hung Yang5, I-Lun Shih1, Hong-Shiee Lai2, and Tiffany Ting-Fang Shih1
1Medical Imaging and Radiology, National Taiwan University Medical School and Hospital, Taipei, Taiwan, 2Surgery, National Taiwan University Medical School and Hospital, Taipei, Taiwan, 3Internal Medicine, National Taiwan University Medical School and Hospital, Taipei, Taiwan, 4Nuclear Medicine, National Taiwan University Medical School and Hospital, Taipei, Taiwan, 5Oncology, National Taiwan University Medical School and Hospital, Taipei, Taiwan
We demonstrated that PET/MRI provides numerous useful imaging biomarkers for clinical staging and pathological grading in patients with pancreatic cancer or periampullary cancer. ADCmin was lower in tumors with N1 and an advanced TNM stage. Choline levels were higher in T4 and poorly differentiated tumors. Tumors with high glucose metabolic activity, as reflected by MTV and TLG, were at a more advanced T stage, exhibited lymph node and distant metastasis, and were at an advanced TNM stage. Moreover, compared with MTV or ADCmin alone, the MTV/ADCmin ratio demonstrated the highest predictive ability for determining the clinical TNM stage. Thus, integrated PET/MRI could provide complementary information on tumor characteristics, and these combined data could have stronger clinical or pathological implications than MRI or PET alone.

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