Shortened PET protocol allows accurate assessment of cancer patients

A shortened PET data acquisition protocol provides quantitative assessment of tissue viability and offers greater comfort for cancer patients, according to a report in the December Journal of Nuclear Medicine.

Dynamic data acquisition allows for more accurate assessment of tissue viability, the authors explain, but it demands more time for data acquisition and more sophisticated software for data analysis. “According to our experience,” Dr. Ludwig G. Strauss from the German Cancer Research Center, Heidelberg, Germany told Reuters Health, “the use of quantitative data is especially helpful in two situations: a) early follow up of patients receiving chemotherapeutic treatment in order to predict therapy outcome and b) optimizing tumor staging.” Dr. Strauss and colleagues used 151 dynamic datasets obtained from 60 cancer patients to determine whether meaningful information about vascular fraction (VB) and the rate constant k1 could add to the information obtained with static measurements of 18F-FDG metabolism by PET. The short acquisition protocol consisted of a dynamic acquisition of ten 1-minute frames and a late static image 56 to 60 minutes after tracer injection. Input data using this protocol provided correlation coefficients of 0.9028 for 18F-FDG influx, 0.9195 for VB, and 0.9305 for k1, the authors report, which represents a high degree of accuracy for these measurements of 18F-FDG kinetics. Using the simplest data acquisition protocol (one 10-minute frame immediately after tracer injection and a second 5-minute frame at 56 to 60 minutes) reduced the correlation coefficients only slightly, the report indicates. “A shortened acquisition protocol improves the information which can be obtained from a PET FDG examination without a major increase of scanning time,” Dr. Strauss concluded. “The information about the FDG kinetics helps to get more sensitive parameters for the evaluation of a disease than just looking a the images or using the SUV [standard uptake value] alone.” Dr. Strauss added, “Based on our PET experience (we are working with PET tracers for more than 20 years now), one should try to gain as much data from a radioisotope study as possible. The patient receives a radiation dose by the PET examination, so it is an obligation for the physician to retrieve the maximum of information that can be obtained from a PET tracer study. Both staging as well as therapy management can be improved in this way.”(Source: J Nucl Med 2003;44:1933-1939: Reuters Health: Will Boggs, MD: January 8, 2004: Oncolink)