Recent Publications


Improving PET Quantitation with Denoising, Motion Compensation, and Deblurring

09/15/2017


This article was published in the Nuclear & Plasma Sciences Society newsletter of September 2017

Positron emission tomography (PET) enables 3D visualization of vital physiological information, e.g., metabolism, blood flow, and neuroreceptor concentration by using targeted radioisotope-labeled tracers. Quantitative interpretation of PET images is crucial both in diagnostic and therapeutic contexts. As a result of its unique functional capabilities, PET imaging plays a pivotal role in diagnostics and in therapeutic assessment in many areas of medicine, including oncology, neurology, and cardiology. Accurate quantitation requires correction of PET raw data and/or images for a number of physical effects. These include attenuation correction, randoms and scatter correction, subject motion correction, and partial volume correction. We have developed a range of techniques that address the PET denoising, motion compensation, deblurring problems. Several of these methods greatly enhance the quantitative capabilities of PET particularly by incorporating information from an anatomical imaging modality such as magnetic resonance imaging (MRI).

IMAGE DENOISING
Faced with a fundamental tradeoff between radiation dose and image noise, PET data is inherently noisy. The high levels of noise in PET images pose a challenge to accurate quantitation. This issue is particularly well pronounced at the early time frames of dynamic PET images, which are usually short to capture rapid changes in tracer uptake patterns. In order to improve image quality and quantitative accuracy, statistical image reconstruction algorithms model the Poisson characteristics of PET data and employ numerical optimization algorithms to solve the corresponding optimization problem [1, 2]. Common reconstruction procedures, such as ordered subsets expectation maximization, are therefore routinely followed by a post-filtering step for denoising the reconstructed image. A range of strategies have been proposed for post-reconstruction denoising of both static and dynamic PET images [3, 4]. In recent years, image denoising based on non-local means (NLM) has become popular [5]. Unlike conventional neighborhood filters, which use local similarities, in this technique, the search for voxels similar to a given voxel is no longer restricted to its immediate vicinity.

Full article in PDF

Heat-induced-radiolabeling and click chemistry

02/24/2017


Yuan H, Wilks MQ, El Fakhri G, Normandin MD, Kaittanis C, Josephson L (2017) Heat-induced-radiolabeling and click chemistry: A powerful combination for generating multifunctional nanomaterials. PLoS ONE 12(2): e0172722. doi:10.1371/journal.pone.0172722

Abstract

A key advantage of nanomaterials for biomedical applications is their ability to feature multiple small reporter groups (multimodality), or combinations of reporter groups and therapeutic agents (multifunctionality), while being targeted to cell surface receptors. Here a facile combination of techniques for the syntheses of multimodal, targeted nanoparticles (NPs) is presented, whereby heat-induced-radiolabeling (HIR) labels NPs with radiometals and socalled click chemistry is used to attach bioactive groups to the NP surface. Click-reactive alkyne or azide groups were first attached to the nonradioactive clinical Feraheme (FH) NPs. Resulting ªAlkyne-FHº and ªAzide-FHº intermediates, like the parent NP, tolerated 89Zr labeling by the HIR method previously described. Subsequently, biomolecules were quickly conjugated to the radioactive NPs by either copper-catalyzed or copper-free click reactions with high efficiency. Synthesis of the Alkyne-FH or Azide-FH intermediates, followed by HIR and then by click reactions for biomolecule attachment, provides a simple and potentially general path for the synthesis of multimodal, multifunctional, and targeted NPs for biomedical applications. Download Full Article in PDF

Outline of heat induced radiolabeling (HIR) and click chemistry surface functionalization used to obtain multimodal, targeted NPs.

Neuroplastic Changes in Blind Individuals

12/20/2016


 

This article was initially published by the RSNA Daily Bulletin on November 30, 2016.

Dr. Laura Ortiz-Terán is a clinical radiologist and neuroimaging research scientist at the MGH Gordon Center. She works with Dr. Jorge Sepulcre to investigate the neuroplastic changes occurring in blind individuals, adults and children, using graph theory based resting-state functional connectivity analysis.

Medical Physics Cover Article

07/07/2015


DuttaCoverImage

In the featured article of the latest volume of Medical Physics, researchers of the Gordon Center have presented a complete data acquisition and processing framework for respiratory motion compensated image reconstruction (MCIR) using simultaneous whole body PET/magnetic resonance (MR) and validated it through simulation and clinical patient studies.

By developing and validating a PET/MR pulmonary imaging framework, the authors show that simultaneous PET/MR, unique in its capability of combining structural information from MR with functional information from PET, shows promise in pulmonary imaging.

Joyita Dutta, Chuan Huang, Quanzheng Li and Georges El Fakhri. Pulmonary imaging using respiratory motion compensated simultaneous PET/MR. Med Phys 42, 4227 (2015);

[Link to article]

New Book

01/08/2015


StatComp

A book Statistical Computing in Nuclear Imaging authored by a member of the center Dr. Arkadiusz Sitek was recently published by the CRC Press.

Statistical Computing in Nuclear Imaging introduces aspects of Bayesian computing in nuclear imaging. The book provides an introduction to Bayesian statistics and concepts and is highly focused on the computational aspects of Bayesian data analysis of photon-limited data acquired in tomographic measurements.

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Recent Publications

04/15/2014


Recent publications are listed below.

For a full list of publications, please see the Publications page.


  • W. Zhu, Q. Li, B Bai, PS Conti, RM Leahy. Patlak image estimation from dual time-point list-mode PET data. IEEE Trans. Medical Imaging, in press, 2014
  • Y. Petibon, C. Huang, J. Ouyang, T. G Reese, Q. Li, S. Syrkina, Y-L Chen and G. El Fakhri. Relative role of motion and PSF compensation in whole-body oncologic PET-MR imaging. Medical Physics, in press, 2014
  • Bai B, Lin Y, Zhu W, Ren R, Li Q, Dahlbom M, Difilippo F, Leahy RM. MAP reconstruction for Fourier rebinned TOF-PET data. Phys Med Biol. 2014 Feb 21; 59(4):925-49.
    View in: PubMed
  • Y. Lin, J. P. Haldar, Q. Li and R. M. Leahy. Sparse Constrained Mixture Modeling for the Estimation of Kinetic Parameters in Dynamic PET. IEEE Transactions on Medical Imaging. 2014; 33(1):173-185.
  • Guo J, Guo N, Lang L, Kiesewetter DO, Xie Q, Li Q, Eden HS, Niu G, Chen X. 18F-Alfatide II and 18F-FDG Dual-Tracer Dynamic PET for Parametric, Early Prediction of Tumor Response to Therapy. J Nucl Med. 2014 Jan; 55(1):154-60.
    View in: PubMed
Read more...

Nature Publication

03/04/2014


Publication in Nature
Charalambos Kaittanis, Travis M. Shaffer, Anuja Ogirala, Santimukul Santra, J. Manuel Perez, Gabriela Chiosis, Yueming Li, Lee Josephson & Jan Grimm. Environment-responsive nanopores for therapy and treatment monitoring via molecular MRI quenching.
Nature Commun. 5, March 2014

[PubMed link] [Nature link]
natureNanoprobes2014

Reprinted by permission from Macmillan Publishers Ltd: Nature Communications, copyright 2014

Respiratory motion correction

08/30/2012


Researchers of the Gordon Center (previously CAMIS) have recently presented an approach to respiratory motion correction using simultaneous PET/MR that yields unprecedented improvements in image quality by taking advantage of MR motion information during the PET scan. The approach was tested and validated in rabbits and non-human primates and is now being evaluated in the clinical setting. [2012 JNM Cover]

Chun SY, Reese TG, Ouyang J, Guerin B, Catana C, Zhu X, Alpert NM, El Fakhri G. MRI-Based Nonrigid Motion Correction in Simultaneous PET/MRI. J Nucl Med. 2012 Aug; 53(8):1284-91.
View in: PubMed

JNM_Cover