CABI

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Image of the Week

SPECT/PET

Introduction

Dual Isotope

Nuclear imaging via emission tomography is highly sensitive and enables studies of a wide range of physiological and pathological processes in vivo. Nuclear imaging is based on the detection of gamma rays that are emitted by radionuclides injected into the organism. Images depict the spatial distribution of the radionuclides in the body according to their pharmacokinetic behaviour. Two nuclear imaging techniques exist, and can be distinguished due to the use of different types of radionuclides; single photon emission computed tomography (SPECT), and positron emission tomography (PET).

With the advance of preclinical imaging technology it is now possible to image the distribution of picomolar amounts of radiopharmaceuticals with a high spatial resolution of <1mm within minutes to tens of minutes. Moreover, combining SPECT and PET with anatomical imaging, such as X-ray CT or MRI, enables the precise localisation of these radiopharmaceuticals. This sensitive technology enables further understanding of the mechanisms of disease and the development of novel therapeutic strategies.

Central to emission tomography are the radiopharmaceuticals (also known as imaging probes or tracers) which are designed to localize in specific organs/tissues or enter into physiological function and highlight metabolic information. Radiopharmaceuticals generally consist of a radionuclide attached to a chemical moiety or pharmaceutical specific for a biological target, such as an endogenous receptor.

Such radiopharmaceuticals are used clinically for diagnosis and therapy of a wide range of conditions and diseases. Some commonly used radiopharmaceuticals are: 18F-FDG, a radiolabeled glucose analogue used in PET imaging to study glucose metabolism; 99mTc-HMPAO (exametazime) used in SPECT imaging for the detection of regional cerebral blood flow; 99mTc-Sestamibi used in cardiac imaging to study blood perfusion; and 131I-tositumomab used in radioimmunotherapy to treat follicular lymphoma.

Facility resources:

  • Imaging systems: The preclinical nuclear imaging facility at CABI houses a state-of-the-art dual modality NanoSPECT/CT system with a sub millimetre SPECT spatial resolution and up to 35µm X-ray CT resolution.
  • Radionuclide’s and radiopharmaceuticals: Together with the newly established radiochemistry department, lead by Dr. Erik Arstad , the facility benefits from some of the most advanced chemical and analytical equipment as well as access to a wide range of PET and SPECT isotopes and radiopharmaceuticals both established and experimental.
  • Analytical resources: to complement in vivo imaging studies, the facility offers extensive equipment and resources enabling automated gamma counting for radiotracer/pharmaceutical biodistribution evaluation, cryostat sectioning of isolated organs, fluorescent phosphorimaging, and radio-HPLC/TLC to examine blood and serum metabolites.
  • Multidisciplinary, multimodality: amidst a team of multidisciplinary scientists, nuclear imaging studies are enriched by information obtained from parallel imaging modalities. Each imaging modality has inherent strengths and weaknesses, and this is why at CABI we are developing multimodal methods whereby animals can be imaged sequentially on multiple platforms (Optical, MR, ultrasound, photoacoustic) so that maximum information can be gathered to answer a biological question.
  • Cell culture: Supporting our cell tracking projects are the newly refurbished cell culture laboratories at the Cancer Institute, designated and compatible for radioactive work

Role within UCL

The preclinical nuclear imaging facility is at the crossroad of translational medicine at UCL and UCL Partners, bridging the gap between benchtop research to bedside clinical applications. In close collaboration with the Department of Chemistry, and the Division of Medicine the development of novel imaging tracers and therapeutic radiopharmaceuticals can be evaluated in vivo in a variety of disease models.The facility is perfectly suited to support drug discovery programmes as well as study disease processes and response to new therapies.

The focus at CABI is predominantly preclinical imaging, and together with the Department of Medical Physics and Bioengineering, the Centre for Medical Image Computing (CMIC), and industrial partnerships, we strive to advance preclinical instrumentation and methodology. One goal is to improve the sensitivity, and spatial and temporal resolutions.

On the computational front, our aim is to develop algorithms and methods to achieve fast reconstruction and image processing, based on prior physiological information obtained by complementary imaging techniques, and to provide superior image quality and quantitative accuracy.

External collaborations

We are always interested in expanding our imaging to new applications and finding collaborations that provide opportunities to employ and develop our techniques. Availability and priority will be given to collaborative projects, although the facilities can be made available purely as a resource.

Contacts:

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Adam Badar Lead postdoctoral researcher

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Mark Lythgoe Director of CABI

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Erik Arstad

Page last modified on 12 sep 11 14:56