Jonathan Hero Chung MD, Presenter: Research Grant, Siemens AG Royalties, Amirsys, Inc

Demitry Kazlouski, Abstract Co-Author: Nothing to Disclose

Hope McGee, Abstract Co-Author: Nothing to Disclose

Ramya Rajaram, Abstract Co-Author: Employee, Siemens AG

David Augustine Lynch MBBCh, Abstract Co-Author: Research support, Siemens AG Scientific Advisor, PAREXEL International Corporation Consultant, Boehringer Ingelheim GmbH Consultant, InterMune, Inc Consultant, Gilead Sciences, Inc Consultant, F. Hoffmann-La Roche Ltd Consultant, Veracyte, Inc Research support, Johnson & Johnson Research support, AstraZeneca PLC

Previous studies have shown mixed results in the setting of dual time-point 18FDG PET in characterizing indeterminate pulmonary nodules as benign or malignant. The purpose of this study was to determine if respiratory gating would increase the accuracy of the dual time-point PET technique in characterizing indeterminate pulmonary nodules.

Subjects with pulmonary nodules ranging in size from 6-20 mm, being evaluated with 18FDG PET/CT were prospectively recruited for our study. Subjects were imaged with 18FDG PET/CT one and two hours after injection of approximately 15 mCi 18FDG using static and phase-based respiratory-gated techniques. The maximum SUVs of pulmonary nodules were measured on static PET images as well as for every gate of respiratory-gated PET images. Malignancy or benignity was determined by tissue biopsy or follow-up imaging.

There were 29 malignant and 78 benign nodules. The maximum SUV of malignant nodules was statistically higher than that of benign nodules at the first (8.35+/- 7.29 vs. 2.34 +/-2.13) and second (10.39 +/- 8.91 vs. 2.55 +/-2.42) hour time points (p-values <0.0001). The percentage change in the maximum SUV values for respiratory-gated data (19.3% +/- 30.2% vs 7.5% +/- 20.1%, p-value 0.0210) and static data (23.3% +/- 60.0% vs 3.8% +/- 23.0%, p-value 0.0161) from 1st to 2nd time points was significantly higher in malignant than benign nodules. This relationship persisted even when considering nodules with a maximum SUV of greater than 3.0 (with gating: 29.0% +/-23.7% vs 9.9% +/- 29.0%, p-value 0.0107; without gating: 32.3% +/-53.3% vs 2.0% +/- 26.9%, p-value 0.0217).

There is a statistical difference in percentage change of maximum SUV values from 1st to 2nd time points between malignant and benign pulmonary nodules for both respiratory-gated and static PET images. This relationship persists even when considering pulmonary nodules with substantial 18FDG uptake (maximum SUV greater than 3.0). There was less dispersion of percentage change of maximum SUV across time points with than without respiratory gating (standard deviation of 30% compared to 60%).

A dual-time point technique may be helpful in characterizing indeterminate pulmonary nodules as malignant or benign even in nodules with substantial 18FDG uptake.

Chung, J, Kazlouski, D, McGee, H, Rajaram, R, Lynch, D, Dual Time-point and Respiratory-gated 18FDG PET/CT in the Characterization of Indeterminate Pulmonary Nodules.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14018972.html