Daily Bulletin 2015

Next Generation PET/CT Technology Paves Way to Better Patient Care

Monday, Nov. 30, 2015

The next generation of PET/CT scanners using solid-state technology and all-digital data are a substantial improvement in image quality over current technology, said study author Michael Knopp, M.D., during a Sunday session.

Michael Knopp, M.D.

Michael Knopp, M.D.

In addition to improving visual and quantitative quality, accuracy and measurement reproducibility for clinical oncologic PET imaging, the research by Dr. Knopp and colleagues indicates that the advanced technology dramatically reduces tracer dose in clinical PET imaging.

"The system and the technology have performed remarkably well," said Dr. Knopp, director of the Wright Center for Innovation and Biomedical Imaging at Ohio State University. "It allows us to visualize with a higher definition and higher reconstruction maintenance, which can translate into better lesion detectability and quantitative accuracy."

Dr. Knopp presented the study in which blinded readers compared images from current photomultiplier tubes to images scanned on the Vereos 64 TF scanners by Philips Healthcare, which replace the tubes with a solid-state digital photon counting chip. Comparing the two types of scanners in this Phase 1 study, the blinded readers reported higher confidence in lesion detectability and better delineation of lesions on scans of the same 30 patients with various malignant tumors.

"This is not your father's PET," said Martin Pomper, M.D., whose talk at the session focused on next-generation tracers.

Also, confidence of lesion detectability was rated significantly higher on the digital PET when evaluating lesions of less than 15 mm, Dr. Knopp said.

"This research demonstrates that the new generation of PET scanners can be used as a better clinical tool or biomarker, especially for today's targeted therapeutics," Dr. Knopp said. "The images look crisper and more precise and provide a truer metabolic coefficient ratio."

Increased Precision, Lower Dose

The latest scanners have a number of advancements over multiplier tubes, Dr. Knopp said. First, the scanner has a direct 1-to-1 ratio with the crystal, which is a 50-fold increase over photomultiplier technology. Second, the temporal resolution of the new scanner has improved from 500 picoseconds down to 325 picoseconds. Finally, the imaging is digital from beginning to end, dramatically improving image reconstruction.

"We can get very high resolution reconstruction without any compromise in quality," Dr. Knopp said, adding that slice thickness can go to as thin as 1-2 mm vs. the current 3-4 mm slice thickness.

The study also suggested that the new scanners can produce high-quality images using half the dose of current technology. Tracer dose simulations indicate that no impact on quality and detectability was found while reducing the count equivalency from 13 millicurie (mCi) fluoro-2-deoxy-d-glucose (FDG) to 6 mCi, Dr. Knopp said.

The increased precision of the new technology will lead to clinical improvements in detecting metabolic activity. "We are surprised that we can now see smaller metabolic activity at a level of clarity and precision that we have not seen before, without a loss of specificity," Dr. Knopp said.

Radiologists testing the new technology as part of the study could detect lesions smaller than 1cm with clarity, which was impressive, Dr. Knopp said. For the study's purposes, however, the researchers selected 1.5 cm as a standard.

Dr. Knopp said the new scanners could have non-oncological uses such as in sports medicine and neuroscience.

"This technology can redefine our clinical work, especially with some of the exciting new tracer doses on the horizon," Knopp said.

Question of the Day:

We just purchased a new CT scanner from a different vendor and it's like trying to learn a new language to understand their parameters. How do I learn the new nomenclature?

Tip of the day:

Even if it is your personal lead apron, if it is stored on-site at the clinic, it must be checked annually as part of a quality assurance program.

The RSNA 2015 Daily Bulletin is owned and published by the Radiological Society of North America, Inc., 820 Jorie Blvd., Oak Brook, IL 60523.