University of Wisconsin–Madison

PET

The Brain Imaging Core houses a complete PET research facility.

Radionuclide Production: Since most of the commonly used PET tracers have a short radioactive half-life, on-site production of the radioactive isotopes is required.  Radionuclide production is carried out with the following particle accelerators: 1)  a GE PETtrace 16 MeV proton / 8 MeV deuteron cyclotron purchased with an NIH Instrumentation grant (1S10 RR023033) housed in the UW Medical Physics facility and 2) a National Electrostatics Corporation 9SDH-2 electrostatic tandem accelerator, capable of accelerating >100uA of protons or deuterons to 7 MeV located in the Waisman Center PET Radiochemistry Lab.  Both accelerators are equipped with high yield targetry systems for the production of 15O, 13N, 11C, and 18F and scores of other positron emitting radionuclides.  The accelerator vaults at both locations allow for flexible target configurations, increased reliability and ease of maintenance.  While most accelerators irradiate gas, liquid, and solid targets, the vault spaces allow for beam lines for slanted-target irradiations of solid or molten material, further supporting the production of non-conventional medical isotopes.  The two accelerator labs are located in separate buildings located approximately 300 meters apart.  Bi-direction transport of radionuclides between labs is routinely conducted via an underground conduit containing multiple gas and liquid transfer lines.

Radiopharmaceutical Synthesis:​ The PET Radiochemistry Lab is equipped with dual fume hoods and a class 10,000 clean room with class 100 laminar flow ​hood are available for radiopharmaceutical preparation. The lab is well equipped for continuous (in-line) production and delivery of short-lived tracers. The radiochemistry lab is also a well-suited for organic chemistry syntheses with access to modern analytical instruments, suitable for precursor synthesis and tracer development. Equipment in this lab include: Waters isocratic HPLC systems (5) with UV-Vis detectors and flow-through radioactivity detectors, computerized programmable chemistry units (2) used routinely for performing nucleophilic reactions with 18F and methylation reactions for 11C radiotracers, SRI Gas Chromotography Unit with TCD and FID detectors, LSC beta detectors (5) and  ​single channel analyzers (SCA) with CsI detectors (2) with the appropriate data collection and analysis hardware and software. Other equipment include a Endosafe Bacterial Endotoxin Testing system, refrigerators ​(2), freezer (1), 18-Megaohms water purification system, glassware drying oven, microbalance, automatic ​liquid scintillation counter, refrigerated ultracentrifuge, vacuum line system, rotary evaporators and dose calibrators. The facility includes separate animal handling and transport accommodations, including appropriate air handling considerations. Other support resources include: a fully equipped machine shop; developmental and  ​diagnostic electronics apparatus; a clean stainless steel transfer line network for specialty gases and liquids, ​​including radioactive and corrosive materials; and ample bench space for cutting edge instrumentation development and repair.

Human scanning: The scanning facilities consist of a Siemens ECAT EXACT HR+ PET scanner and its adjacent control room, subject prep room, and blood metabolite analysis lab.  The PET scanner room is also equipped with a positional computer monitor for performing computer tasks during the acquisition of the scans.  Investigators also have access to a newly sited GE Signa PET/MRI system in the WIMR facility.  This system permits simultaneous acquisition from a 3T MRI scanner and LYSO PET scanner with time-of-flight technology.

The ECAT EXACT HR+ PET scanner consists of 4 detector rings of 72 BGO blocks per ring.  Each block contains an 8 x 8 array of discrete detector elements with dimensions of 4.39 x 4.05 x 30 mm3, providing 63 contiguous 2-D image planes through an axial field of view (FOV) of 15.5 cm and a patient port diameter of 56.2cm. The rings are separated by extendable tungsten septa for acquisition in both 2D and 3D modes. The transaxial intrinsic resolution of this scanner is 4.3 mm FWHM, and axial intrinsic resolution is 4.7 mm FWHM in the center of the field of view. Reconstructed spatial resolution for a head-shaped object is in a nearly isotropic resolution of 6mm FWHM throughout the entire region of the brain.