Poster - Thur Eve - 20: Serial FDG 4DPET imaging during radiotherapy in advanced lung cancer patients

N Becker; K Clarke; V Pekar; J St-Hilaire; C Leavens; J Higgins; A Bezjak; A Sun; J-P Bissonnette

doi:10.1118/1.4740128

Poster - Thur Eve - 20: Serial FDG 4DPET imaging during radiotherapy in advanced lung cancer patients

Med Phys. 2012 Jul;39(7Part3):4628. doi: 10.1118/1.4740128.

Authors

N Becker^{1

2}, K Clarke^{1

2}, V Pekar^{1

2}, J St-Hilaire^{1

2}, C Leavens^{1

2}, J Higgins^{1

2}, A Bezjak^{1

2}, A Sun^{1

2}, J-P Bissonnette^{1

2}

Affiliations

¹ Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Toronto, Canada.
² Dept. of Radiation Oncology, University of Toronto, Toronto, Canada.

PMID: 28516698
DOI: 10.1118/1.4740128

Abstract

The availability of respiratory synchronized PET (4DPET) imaging has enabled more accurate analysis of metabolic response since motion blur is minimized. We present our preliminary analysis of serial FDG 4DPET images acquired at weeks 0, 2, 4, and 7 during radiotherapy of seven stage II-III NSCLC patients. The tumor and nodal PTV of the week 0 images restrained a 4DPET image thresholding algorithm to automatically contour SUV levels ranging from 20 to 80% of the maximum SUV, creating an intensity volume histogram (IVH) for each week. These contours allowed analysis of PET volumes and standard PET metrics such as SUV_max and SUV_mean . We found a trend for decreasing SUV_max and SUV_mean over a treatment course in both the tumor and nodal regions. On average, the SUV_max within the tumor decreased by 17±13% (1 SD) after 2 weeks, 30±13% after 4 weeks, and 39±19% after 7 weeks of radiotherapy. Decreasing volume trends were also observed in the 20 to 80% max SUV autocontours, ranging from 26±29% to 50±40% respectively, over 7 weeks of treatment. Only one patient demonstrated an increase in FDG uptake within the tumor volume between week 0 and week 2 of treatment, and was also the only patient to recur locally at 3 months following treatment. Changes in tumor metabolism over the course of advanced NSCLC radiotherapy are quantifiable with serial FDG 4DPET imaging. Preliminary analysis suggests that variations in these trends could be useful in identifying non-responding patients that may require an alternative radiotherapeutic approach.

Keywords: Cancer; Image analysis; Image motion analysis; Lungs; Medical imaging; Radiation therapy.