Molecular Imaging Overview
In the field of Molecular Imaging, in vivo Preclinical Imaging has become increasingly important to academic researchers...and especially to those involved in the Drug Development Process
Recent improvements in the Molecular Imaging technologies employed to image small animals…are helping to generate better data, and at a more prodigious rate than ever!
In the past, Mouse & Rat models of Human Disease are usually studied using invasive techniques, which sacrifice the animal.
And although these techniques are well established…there are several major disadvantages to this approach:
- A large number of animals is necessary in order for a study to achieve statistical significance.
- Follow-up or longitudinal studies are generally not possible on the same animal.
- Metabolism studies, for efficacy, are difficult to obtain.
- A large amount of economic and labor resources is required.
However, over the past few years, in vivo Imaging Systems for small animals have become increasingly popular…including:
- X-ray micro CT (computed tomography)
- MRI (magnetic resonance imaging)
- Microscopy
- Ultrasound
- Micro-PET (positron emission tomography)
- Micro-SPECT (single photon emission computed tomography)
- Optical (luminescence & fluorescence)
Of these technologies, only the Nuclear Imaging Modalities (PET & SPECT) can provide the sensitivities required to obtain the same physiological imaging acuity in small animals…as can be obtained from humans.
Such modalities greatly facilitate the translation of preclinical studies to applications in the clinic!
Although Micro-PET and Micro-SPECT devices can be used for imaging small animals, they each suffer from critical shortcomings…
Micro-PET: For mouse imaging, the positron range of PET tracers blurs the images so much, that micro-PET systems are not capable of measuring tracer distributions and kinetics within organs…and are limited to only imaging large regions of interest.
Micro-SPECT: On the other hand, conventional single-pinhole micro-SPECT devices suffer from low detection sensitivity, due to the use of the required imaging pinhole collimators to achieve good resolution. Although detection sensitivity can be improved by enlarging the pinhole, it comes at the detriment of lower image resolutions.
But there are also distinct Advantages to using SPECT…rather than PET tracers…
The fact is that SPECT tracers are widely available from a mature isotope distribution network, are easily labeled, and don’t require an expensive on-site cyclotron/ radiochemistry production facility. Therefore, in comparison, the use of SPECT tracers is relatively inexpensive…and its longer half-lives make SPECT well suited (if not required), when biologically-active radiopharmaceuticals have slow kinetics.
Conquering this Sensitivity vs. Resolution trade-off has proved tantalizingly elusive to preclinical researchers for years. …Until now!
With the recent introduction of its dual-modality NanoSPECT/CT system…Bioscan has succeeded at dramatically increasing detection sensitivity, while improving image resolution to the sub-mm or nL level!
Using patented Multiplexed Multi-Pinhole SPECT (MMP-SPECT) technology, NanoSPECT/CT obtains images from up to 40 pinholes—simultaneously--thus creating tomographic images much faster…and with less injected tracer activity.
The results obtained so far from leading researchers around the world…prove that we’re taking preclinical molecular imaging to a new level of performance! (visit www.spect-ct.com)
