Industry experts offer insight into PET/CT

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CHICAGO, Nov. 26—A trio of experts in PET and PET/CT imaging led the diagnostic radiology refresher course “Clinical PET and PET/CT Imaging – PET Basics” at the 93rd annual meeting of the Radiological Society of North America (RSNA), providing the near-capacity crowd with insight into using the modalities.
Making up the trio was David W. Townsend, PhD, professor of medicine and radiology, director of cancer imaging and Tracer Development Program, University of Tennessee Medical Center; Richard L. Wahl, MD, director of nuclear medicine/PET, Johns Hopkins University; and Harry Agress, MD, director, division of nuclear medicine & PET Center, senior attending radiologist, Hackensack University Medical Center.

Townsend presented “Physics and Instrumentation for PET” during which he reviewed PET physics and its influences on the design and performance of the instrumentation. He provided a look at the advances in CT, including the increased number of axial slices, faster rotation, improved dose, faster scan times and dual Straton x-ray tubes. He also outlined PET improvements, especially in combination with CT. New scintillators now provide five times more light; improving signal-to-noise; and better special resolution with new 13x13 blocks (versus 8x8). Additionally, advances in reconstruction techniques are a great aid in moving forward, he said.

In comparing the five PET/CT scanners on the market: Siemens Medical Solutions, GE Healthcare, Philips Medical Systems, Hitachi Medical Systems America and Toshiba America Medical Systems, Townsend highlighted Philips as the first vendor with time-of-flight and Siemens’ increased planar sensitivity with extended axial field-of-view. He noted the trend is to move toward 3D with the systems.

As to where the market has been and is going, Townsend said that while PET sales have declined in recent years, PET/CT sales have remained fairly consistent over the past five years.

In his presentation “Biological Targets and Radiotracers for PET,” Wahl explained the rationale for use of FDG, the most common tracer, in tumor imaging for common cancers. He outlined the necessary preparation for FDG PET and described how PET is used for individualized treatment plans.

Outside of imaging for cancer, FDG PET is used to diagnosis Alzheimer’s disease has a 90 percent accuracy, Wahl said. The impact of PET/CT on cardiac disease also is notable. FDG also is effective for infection imaging and inflammation.

To present “PET Imaging Protocols and Normal Anatomy/Variants,” Agress made it a point to show as well as tell. He had the house lights turned down and told the audience to look at the images rather than take notes. Through a series of images PET and PET/CT, Agress provided examples of patients with various conditions, stages of diagnosis, treatment or recovery, false-positives and factors that affect scans and diagnosis. The images told the story with Agress providing the story behind the story.