Maggie Mei Kei Fung¹, Abhishek Sharma², Justin Lahrman³, Lloyd Estkowski⁴, and Ersin Bayram^5
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. 

Xiaoyi Wang¹, Ning Wu¹, Yanfeng Zhao¹, Han Ouyang¹, Lizhi Xie², Jin Zhang¹, Li Liu¹, Wenjie Zhang¹, Rong Zheng¹, Ying Liang¹, and Ying Liu^1
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.

Mohammad Mehdi Khalighi¹, Gaspar Delso², Praveen K. Gulaka³, Audrey Peiwen Fan³, Bin Shen⁴, Aileen Hoehne⁴, Prachi Singh³, Jun-Hyung Park⁴, Dawn Holley³, Frederick T. Chin^3,4, and Greg Zaharchuk^3,4
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.

Christoph Kolbitsch^1,2, Radhouene Neji³, Matthias Fenchel⁴, and Tobias Schaeffter^1,2
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).

Yoann Petibon¹, Behzad Ebrahimi¹, Timothy G Reese^1,2, Nicolas Guehl¹, Marc D Normandin¹, Nathaniel M Alpert¹, Georges El Fakhri¹, and Jinsong Ouyang^1
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.

Christian Würslin¹, Dominik Fleischmann², and Roland Bammer^1
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.

Liliana Lourenco Caldeira¹, Theodoros Kaltsas¹, Jürgen Scheins¹, Elena Rota Kops¹, Lutz Tellmann¹, Uwe Pietrzyk¹, Christoph Lerche¹, and N. Jon Shah^1,2
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. 

Daehyun Yoon¹, Deepak Behera¹, Dawn Holley¹, Pamela Gallant¹, Ma Agnes Martinez Ith², Ian Carroll³, Matthew Smuck², Brian Hargreaves¹, and Sandip Biswal^1
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.

Claudia Calcagno^1,2, Carlos Perez-Medina^1,2, Tina Binderup³, Mark E Lobatto⁴, Seigo Ishino^1,2, Mootaz Eldib^1,2, Philip Robson^1,2, Sarayu Ramachandran^1,2, Thomas Reiner⁵, Edward Fisher⁶, Zahi A Fayad^1,2, and Willem JM Mulder^1,2
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.  

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 Shih^1
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.