PET and CT Imaging
“Siemens Medical Solutions makes small-animal PET, SPECT, and CT imaging scanners,” said Anne M. Smith, Ph.D., director of preclinical collaborations, Siemens Healthcare Molecular Imaging. “For PET, we have the Inveon small bore system with a 12 cm opening and a larger microPET 22 cm bore system that can be used for primates and multirodent studies. The 22 cm bore is the only primate-sized system on the small animal PET imaging market.”
Two challenges that vendors encounter in the PET small animal arena are sensitivity and resolution. “Creating greater sensitivity allows the use of less radioactive dose or the same dose which gives more signal,” explained Dr. Smith. “We’ve increased the sensitivity from less than 4% to greater than 9.5%, and improved the resolution from greater than 2 mm to less than 1.6 mm in approximately a seven-year period.”
Dr. Smith’s group, part of the molecular imaging division at Siemens, also manufactures clinical molecular imaging systems, cyclotrons, and radiochemistry equipment. In addition, the division distributes radioisotopes via PETNET operations. “Our portfolio ranges from radioisotope delivery and biomarker discovery to small-animal imaging and clinical imaging solutions,” said Dr. Smith.
In the CT realm, Siemens’ systems “give users the resolution needed to do ex vivo studies and the field of view required for in vivo studies,” she reported. “Customers demand more multimodality imaging; our Trimodal option provides PET, SPECT, and CT on the same gantry. Users also require more streamlined workflow, which not only includes the acquisition software but also the analysis software.
“We offer the Inveon Research Workplace (IRW) to fill this need. We plan to expand IRW’s multimodality imaging capabilities to include other modalities, such as optical, MRI, and ultrasound.” Dr. Smith noted that chemistry and molecular biology to develop new PET biomarkers as well as biomarkers in other modalities as being key to continued growth in the field.
Sofie Biosciences launched its GENISYS™ PET imaging system at the meeting. Turnkey installation and user-friendly operation means GENISYS is suitable for large and small labs, according to the company. Integration of physiological control with measurement output provides researchers with reproducible, quantitative information without the use of traditional, expensive hardware architectures.
“PET should be less complicated and available to anyone who wants to incorporate it into their research routine,” said Patrick Phelps, president and CEO. “Sofie worked closely with the UCLA Crump Institute to develop a next-generation PET system that provides people with impressive images and the output they desire, all within an imaging device that manages the health of your animal.”
Carestream Molecular Imaging demonstrated its multimodal technology at the conference. “It allows multispectral fluorescence, luminescence, and radioisotope imaging combined with x-ray imaging without ever moving the animal,” said Bill McLaughlin, director of advanced research and development.
“This makes it possible to precisely coregister the anatomical location of molecular signals from optical and nuclear imaging. Others attempt this, but we can do it precisely because all of these different image modalities are taken in the same system and at the same focal plane.”
McLaughlin noted that the nature of Carestream’s product’s design is a key factor in meeting some of the greatest challenges in the field. “One thing we did was calibrate the light source in such a way that the field is flattened to correct for any uneven lighting on the animals. With our system, it doesn’t matter where you put the animal on the surface, you will get consistent, repeatable results.”
Carestream systems also allow imaging from underneath the animal so it can be placed in its natural position—on its belly—for most of the imaging that is done on tumors and other disease states. “Gravity helps us out by spreading the animal more evenly on our imaging surface, which serves as the focal plan for all the different modalities,” added McLaughlin. “One thing that is important from an image and measurement standpoint is positioning the animal in a consistent way.
“Researchers need repeatable, measurable results in a high-throughput setup. We try to take as much variability out of animal imaging as we can so that researchers not only get great images, but also get reliable data.”