CTSC:CHBresources:SAIL
Small Animal Imaging Laboratory (SAIL)/Kresge Laboratory
The SAIL has been conceived as a pre-clinical imaging core resource whose primary mission is to support research using small animal models as surrogates for testing and exploring human diseases, diagnoses, treatments, and physiology.
Instrumentations
- microPET Siemens Focus 120 . High-resolution, small-animal PET scanner that combines high spatial resolution (<1.3 mm) and high sensitivity (>7%) with a bore size (12 cm diameter and 7.6 axial length) that is optimized for imaging mice and rats. For radioactive agents, we are routinely imaging 18F 2-fluoro-2-deoxy-D-glucose (FDG) and 18F sodium fluoride (NaF). We have imaged 18F fluorothymidine (FLT) and are in the process of developing the capability to image 18F FHBG as well as an 18F labeled αVβ3 imaging agent.
- Imaging and Diagnostic Benefits: PET systems allow imaging of metabolic processes relative to anatomical images. SPECT and PET produce a variety of functional images. This has made PET and SPECT invaluable tools for the study of animal models of human disease; transgenic animals; pharmacological agents in drug development; novel drug delivery and gene therapy approaches; new molecular imaging assays; and new radiotracers for use in diagnostic imaging. PET and SPECT have been invaluable in understanding, diagnosing or staging of cancers and neurological diseases such as epilepsy.
- microCAT II Siemens High-resolution (27 microns in standard mode and 15 microns in high-resolution mode) CT scanner designed specifically for imaging small animals such as mice and rats, as well as specimens. The radiation detector is configurable such that, for mice, the transaxial field of view is 5.4 cm and the axial field of view is 8 cm, whereas for rats, the transaxial field of view is 8 cm and the axial field of view is 5.4 cm. We have utilized microCT for tumor imaging, for anatomical correlation for our microPET studies as well as for ex vivo imaging (e.g. structural analysis of porcine cardiac valves). The host computer for the MicroCAT II is a dual 3.2 GHz processor workstation with 2 GB of RAM and a 600 GB RAID storage system and a high resolution 20.0 inch flat-panel display. A separate processing system is used for real-time reconstruction. This system uses two processors to generate 512 x 512 x 768 voxel image volumes in real time during a scan.
- Imaging and Diagnostic Benefits: CT has been used extensively to assess trauma and detect and stage certain tumor types and their response to therapy. One of the most powerful applications of CT has been in multimodal imaging involving registration with PET or SPECT data to provide high resolution anatomical and functional information. The Siemens MicroCAT II has proven an essential complementary imaging device in the setting of registration with Siemens Focus 120 microPET images, effectively increasing the quality and accuracy of the imaging data that is generated.
- Ultrasound VisualSonics Vevo 2100 . The Vevo 2100 expands functionality, flexibility and image quality while operating at frequencies never before achieved with solid-state array transducers. The new MicroScan transducers provide increased frame rates, superb contrast and unrivaled detail resolution, a wider field of view and comprehensive analytics. The Vevo 2100 also offers improved imaging capabilities including— superb B-mode (2D) imaging with frame rates up to 1000 fps with multiple focal zones for enhanced image uniformity; m-mode assesses motion in cardiovascular applications; pulsed-wave Doppler (PW) for blood flow quantification; color Doppler shows flow direction, mean velocities & identifies small vessels not seen in B-mode; power Doppler for relative quantification of blood flow; simultaneous modes and steering for easier and faster studies; MicroMarker™ Contrast Imaging – for relative perfusion and targeted molecular data; and 3D Imaging, rendering, reconstruction and volume analysis.
- Imaging and Diagnostic Benefits: The Vevo 2100 micro Ultrasound is easy to use, non-invasive and fast, providing extremely high throughput when needed. This system is the best digital imaging platform available that also has built-in expansion for future capabilities.
- MRI BioSpec Bruker 7T. (Slated for installation by June 2011). The Bruker 7 Tesla MRI Scanner is a high-field, horizontal-bore small animal scanner with a useable bore diameter large enough to accommodate imaging small rabbits, rats, mice, and tissue samples/specimens. The instrument operates at a field-strength of 7.05 T and has a 21 cm clear horizontal bore. The standard gradient insert with this system leaves a useable bore size of approximately 11.4 cm, a typical dimension for small animal imaging.
- Imaging and Diagnostic Benefits: Conventional MRI methods provide exquisite soft tissue contrast, arguably better than any other imaging modality. Owing to the very high spatial resolution of MRI as well as its ability to produce sub-millimeter voxel dimensions, various organs are easily differentiated and pathologies are routinely depicted with great precision. The primary determinants of tissue contrast are proton density (PD) (i.e., the water content in non-fatty tissues) and the tissue relaxation times T1, T2, and T2*. Conventional MRI pulse sequences that have been developed to highlight tissue contrast are based, selectively, upon these parameters. These sequences have innumerable clinical and basic research applications that are specifically aimed at improving diagnostic and disease management capabilities. The addition of the 7 Tesla small animal scanner by June 2011 will substantially enhance the complement of small animal imaging devices to which CHB basic scientists have access within the SAIL.
- ADC/XRE Unicath SP fluoroscope. Large-animal fluoroscopy is available using an ADC/XRE Unicath SP single-plane cardiovascular digital angiography unit with a high-resolution fluoroscopy tube, an advanced image intensifier with full-frame zoom, and an image analysis workstation.
- Faxitron MX-20 Specimen Radiograph System. Provides high-resolution x-ray images of mice and small rats (the system includes a gas anesthesia system) as well the ability to obtain radiographic images of excised tissue samples. The x-ray tube can operate at voltages ranging from 10 to 35 kVp with a maximum tube current of 300 A. The focal spot is 20 um allowing for very high spatial resolution. The system is mounted on a cart and can be moved around the laboratory as necessary.
- Imaging and Diagnostic Benefits: The focal spot of this particular system is 20 microns allowing for very high spatial resolution. The system is mounted on a cart and is highly portable throughout the facility.
- Small solid state gamma camera. For planar Imaging.
Services
- Nuclear Medicine and Molecular Imaging Research Laboratory
The Nuclear Medicine Research Laboratory works towards the development of new radiopharmaceutical agents for potential for use in humans. Among several exciting developments is the synthesis of a new PET agent capable of imaging myocardial perfusion—18F-rhodamine. Owing to the microPET capabilities of SAIL, several rhodamine compounds have been evaluated in vivo to define the agent with the most optimal characteristics. The use of microPET has enabled our group to test these compounds in the intact animal, thus avoiding sacrificing a relatively large number of animals to achieve the goal. Drs. Alan Packard and David Briscoe were recently awarded a Harvard Catalyst Grant to investigate “Biomarkers of Cardiac Allograft Vasculopathy.” Dr. Packard also received a research grant award from the Department of Energy (DOE) to explore “Novel Cyclotron-Based Radiometal Production.”
- Multimodality Imaging and Image Processing
We routinely use both the AMIDE software and the Hermes workstation for fusing microPET and CT and for displaying the images. In addition, Hermes workstations are used for image registration of microSPECT and microPET; and, in the near future, of small-animal MRI. Specifically, the Image J application is used to convert the data from two imaging modalities (e.g., microPET and MRI) to an appropriate image format and the data are transferred to the Hermes system via FTP. One of the data sets is then resampled to match the other, and the results are displayed as an alpha-blended overlay. ROIs drawn on the anatomical data set (e.g., MRI) can then be applied to the functional data set (e.g., PET, SPECT, etc.). Imaging and Diagnostic Benefits: The imaging described above generally provides either functional or anatomical information. PET and SPECT contain very little anatomical information. Functional imaging is commonly registered with anatomical images to localize sites of tracer uptake. Dual mode imaging is already routinely done in clinical PET centers. Dual and triple mode small animal scanners are now commercially available (e.g., PET/CT, SPECT/MRI, PET/SPECT/CT, Optical/CT, etc) and are planned for future implementation within the SAIL.
Contact
S. Ted Treves, MD, Director, Chief of Nuclear Medicine and Molecular Imaging [1]
Frederic Fahey, D.Sc Director of Physics [2]
Frederick Grant, MD [3]
Alan B. Packard, PhD Director of Nuclear Medicine and Molecular Imaging Research[4]
Robert V. Mulkern, PhD [5]
