PET INSERT - simPET
High-resolution Standalone PET or PET/MR Insert
Applications
Webinars
Features
System Overview
The SimPET is a compact and reliable SiPM-based small animal PET system for hybrid imaging and standalone use. The SimPET series is an advanced silicon photomultiplier (SiPM) based PET insert for truly simultaneous
PET/MR imaging with a compact design and low power consumption, and excellent PET detector stability.
Features & Specifications
There are several key benefits of the SimPETTM system:
High Image Quality
Low Maintenance Cost
Exceptional PET Performance
Complete System Installation in Few Days
Simultaneous or Standalone Operation
Low Power Consumption
| Parameter | SimPET-S | SimPET-X | SimPET-L | SimPET-XL |
|---|---|---|---|---|
|
Insert Inner Diameter (cm) |
6.0 |
6.0 |
7.6 |
7.6 |
|
Insert Outer Diameter (cm) |
9.9 |
9.9 |
11.2 |
11.2 |
|
Axial FOV (cm) |
5.5 |
11 |
5.5 |
11 |
|
Sensitivity (%) |
4.7 |
8.1 |
4.0 |
7.4 |
- Crystal Dimension (mm3)
All Models
- 1.2×1.2×10
- Crystal Material
All Models
- LSO
- Spatial Resolution (mm)
All Models
- <1
- Energy Resolution
All Models
- 10
Applications
Oncology is one of the most common applications of PET/MRI in preclinical imaging. Used clinically to detect small metastatic lesions throughout the body, preclinical applications of PET imaging are diverse. PET tracers have been developed to study:
- Cell proliferation
- Apoptosis
- Angiogenesis
- Metastasis
- Gene expression of specific molecular targets
PET imaging may be used on any type of tumor model, as the radiotracers are typically injected intravenously for distribution to all areas of the body. Specifically, PET imaging may be used on orthotopic and transgenic/spontaneous tumors, as well as xenografts or metastatic lesions.
The simultaneously acquired MR image may provide additional insights about the tumors themselves, or surrounding anatomical
- Receptor-ligand interactions
- Substrate transportation
- Nutrient metabolism
The simultaneously acquired MR image may provide additional insights about the tumors themselves, or surrounding anatomical
The image above shows the effect of tumor associated macrophages on tumor hypoxia and aerobic glycolysis, displayed in values of standard uptake values. A T2-weighted fast spin echo (FSE) image was acquired on the M7, compact, permanent magnet MRI system from Aspect Imaging; PET images were acquired simultaneously with the SimPET-S model.
Neurological applications of PET/MRI are commonplace both clinically and preclinically. Preclinical PET tracers have been developed to study:
- Biodistribution of a specific target
- Cerebral blood flow
- Cerebral metabolic rate
- Availability of specific receptors in the brain
- Dopamine transmission
- Plasma membrane transporters
- Receptor binding sites
PET imaging has been used to study the pathological processes, response to therapeutics, and resolution of many disease models, including Parkinson’s Disease, Alzheimer’s Disease, Huntington’s Disease, Stroke, Epilepsy, Traumatic Brain Injury, and Neuropsychiatric disorders.
The co-registration of the PET and MR images provides even greater information to the research with regards to the location of the PET tracer within the various structures of the brain, as well as additional anatomical information which may only be available on the MR image. Multi-modal contrast agents may also help elucidate further the various questions being investigated with these powerful imaging modalities.
Cardiology applications of PET are commonplace both clinically and preclinically. Preclinical PET tracers have been developed to study:
- Myocardial perfusion to examine the extent of stenosis and severity of obstruction
- Myocardial metabolism
- Myocardial viability
- Infarct assessment
- Calcium scoring in coronary artery disease
- Inflammation and plaque development for risk stratification
Many different cardiovascular diseases may be investigated using PET imaging, including coronary artery disease, myocardia infarction, or heart failure.
Co-registration of the PET and MR images provides additional information about the heart and surrounding vasculature, to further elucidate the answers to the questions being asked during these imaging studies.
The recent COVID-19 pandemic has brought to the forefront the importance of PET imaging in immunological and infectious disease research. A survey of the literature shows that preclinical PET imaging has been shown to be invaluable in studying the following:
- Understanding disease progression and pathogenesis
- Diagnosis of disease, by targeting the specific pathogenic agent
- Studying therapeutic efficacy of target compounds
- Optimizing treatment regimes and studying the resolution of infections
- Understanding the host’s immune response to infection
- Studying the efficacy of vaccines
Infectious diseases and immunology are not limited to the study of viruses, but rather go well beyond these specific agents to look at models of bacterial, viral, parasite, and prion infections. The only limitation to this type of work is in the PET tracers available to investigate both the infectious agent as well as the host’s response.
The anatomical information provided by the simultaneously acquired MR image, in these specific studies, may help researchers to better understand the exact location of the infectious agent being studied, or further elucidate the hosts response to the infection or response to the therapy being studied.
Dynamic PET imaging is often used to study the kinetics of a newly developed PET tracer, or to investigate target concentrations, or biodistribution. Time-activity curves are often prepared along with assessments of radiotracer accumulation and biodistribution kinetic modeling.
Simultaneously acquired MR images help to provide the anatomical context necessary to fully understand the dynamic PET images in these types of studies.
The above set of images shows a dynamic scan acquired with the SimPET-X insert, having an axial field of view of 11cm. A mouse was injected, via the tail vein, with 331µCi [18F]-fluorodeoxygluocose (FDG).
A variety of bone diseases may be studied using PET imaging, these include but are not limited to osteoporosis, osteomalacia, rickets, or rheumatoid arthritis.
A wide variety of other diseases, including metabolic disorders, can also be studied using PET imaging.
There is truly no limit on the application of PET in preclinical imaging, it is merely dependent on the development of specific and relevant PET tracers.
The anatomical information provided by the MR images provide the context for the PET signal, and may help further elucidate the answers to the biological questions being asked in these types of studies.
A wide variety of other diseases, including metabolic disorders, can also be studied using PET imaging.
There is truly no limit on the application of PET in preclinical imaging, it is merely dependent on the development of specific and relevant PET tracers.
The above image shows increased metabolic activity in the rear paws in the mouse model of arthritis. These images were acquired using the SimPET-S insert along with the M7, compact, permanent magnet from Aspect Imaging, following an i.v. injection of 300µCi of [18F]- fluorodeoxygluocose (FDG). The K/BxN model is a commonly used mouse model to study arthritic disease. The gradient echo (GRE) MR image, acquired on the M7 system, provides the anatomical context for the PET images.
Performance Evaluation
A recent publication in Molecular Imaging and Biology provides the full details of the system performance, a summary of some key outcomes is provided here.
This authors followed the NEMA NU 4-2008 standard to assess the performance of the SimPET-S insert, along with it’s performance within the M7, compact, permanent magnet MRI system from Aspect Imaging.
The spatial resolution, at the center of the field of view, based on the 3D OSEM reconstruction was found to be 0.7mm without a warm background and 1.45mm with a warm background.
In the hot rod phantom image, seen below, the 0.75mm diameter rods were resolved with incorporation of the point spread function.
The spatial resolution, at the center of the field of view, based on the 3D OSEM reconstruction was found to be 0.7mm without a warm background and 1.45mm with a warm background.
In the hot rod phantom image, seen below, the 0.75mm diameter rods were resolved with incorporation of the point spread function.
The sensitivity of the SimPET-S was found to be 4.21% (energy window = 250-750 keV) in this study. Additional studies have found the sensitivity of the SimPET-X model, within the same energy window, to be greatly improved, measured at 8.14%. The SimPET-X model is designed for use in some of the most commonly used high-field (>3T) superconducting magnets designed for pre-clinical imaging.
Above, is the NEMA sensitivity plots, measured at the transaxial center, for both the SimPET-S (gold) and SimPET-X (blue) inserts; measured with an energy window of 250-750 keV.
The NEC rate of the SimPET-S was found to be 151 kcps at 38.4 MBq, using the same energy window as the sensitivity testing (250-750 keV); while the NEC rate of the SimPET-X was found to be 348 kcps at 26.2 MBq, measured in additional studies. The SimPET-X model is designed for use in some of the most commonly used high-field (>3T) superconducting magnets designed for pre-clinical imaging.
The above is the NEMA Count Rate Performance measurements made for the SimPET-S model insert
The above is the NEMA Count Rate Performance measurements made for the SimPET-X model insert
There were no remarkable differences in signal to noise ratio (SNR) and uniformity of the MR images and PET count rates when using different PET conditions and MRI pulse sequences.
The image demonstrates the compatibility of the SimPET insert with the M7 system from Aspect Imaging. Various MRI pulse sequences including T2-weigheted Fast Spin Echo (T2WFSE), T1-weighted Spin Echo (T1WSE), and a 3D Gradient Echo (3DGRE).
When used with the M7, the compact permanent magnet from Aspect Imaging, the SimPET-S insert is placed within the bore of the magnet from one side, while the animal handling system with the RF coil is inserted from the other side of the magnet fitting within the PET insert.
The image shows the SimPET-S insert positioned to enter into the M7 MRI system from Aspect Imaging. The animal handling system with RF coil enters the M7 from the opposite side.
The diagram shows the configuration of the SimPET-S insert positioned within the bore of the M7 MRI system from Aspect imaging.
Past Webinars - SimPET
Publications & Articles
Tumor-Associated Macrophages Enhance Tumor Hypoxia and Aerobic Glycolysis
System Used:M-Series MRI Tumor hypoxia and aerobic glycolysis are well-known resistance factors for
SimPET: A Preclinical PET Insert for Simultaneous PET/MR Imaging
System Used:SimPET Simultaneous Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) provides