A Prospective Study Comparing Functional Imaging (18F-FDG PET) Versus Anatomical Imaging (Contrast Enhanced CT) in Dosimetric Planning for Non-small Cell Lung Cancer.

Document Type: Original Article

Authors

1 Department of Radiation Oncology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India

2 Department of Nuclear Medicine, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India

3 Department of Radio Diagnosis, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India

4 Department of Pathology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India

Abstract

 Objective(s): 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET-CT) is a well-used and established technique for lung cancer staging. Radiation therapy requires accurate target volume delineation, which is difficult in most cases due to coexisting atelectasis. The present study was performed to compare the 18F-FDG PET-CT with contrast enhanced computed tomography (CECT) in target volume delineation and investigate their impacts on radiotherapy planning.
Methods: Eighteen patients were subjected to 18F- FDG PET-CT and CECT in the same position. Subsequently, the target volumes were separately delineated on both image sets. In addition, the normal organ doses were compared and evaluated.
Results: The comparison of the primary gross tumour volume (GTV) between the 18F-FDG PET-CT and CECT imaging revealed that 88.9% (16/18) of the patients had a quantitative change on the 18F-FDG PET-CT. Out of these patients, 77% (14/18) of the cases had a decrease in volume, while 11% (2/18) of them had an increase in volume on the 18F-FDG PET-CT. Additionally, 44.4% (8/18) of the patients showed a decrease by > 50 cm3 on the 18F-FDG PET-CT. The comparison of the GTV lymph node between the 18F-FDG PET-CT and CECT revealed that the volume changed in 89% (16/18) of the patients: it decreased and increased in 50% (9/18) and 39% (7/18) on the 18F-FDG PET-CT. New nodes were identified in 27% (5/18) of the patients on the 18F-FDG PET-CT. The decrease in the GTV lymph node on the 18F-FDG PET-CT was statistically significant. The decreased target volumes made radiotherapy planning easier with improved sparing of normal tissues.
Conclusion: GTV may either increase or decrease with the 18F-FDG PET-CT, compared to the CECT. However, the 18F-FDG PET-CT-based contouring facilitates the accurate delineation of tumour volumes, especially at margins, and detection of new lymph node volumes. The non-FDG avid nodes can be omitted to avoid elective nodal irradiation, which can spare the organs at risk and improve accurate staging and treatment.

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1. Population based cancer registries. National Centre for Disease Informatics and Research. Available at: URL: http://pbcrindia.org; Accessed on April 2014.

2. Hospital based cancer registries. Indian Council of Medical Research. Available at: URL: http://icmr.nic. in; Accessed on April 2014.

3. Edge SB, Byrd DR. The lung. In: Edge SB, Byrd DR, Compton CC, Pritz AG, Greene FL, Trotti A, editors. American joint committee on cancer (AJCC) cancer staging manual. 7th ed. Chicago: Springer; 2010. P. 253-70.

4. Chang JY, Bradley JD, Govindan R, Komaki R. The Lung. In: Halperin EC, Brady LW, Wazer DE, Perez CA, editors. Perez and Brady’s principles and practice of radiation oncology. 5th ed. New York: Lippincott Williams and Wilkins; 2008. P. 1076-108.

5. Bradley J, Bae K, Choi N, Forster K, Siegel BS, Brunetti J, et al. A phase II comparative study of gross tumor volume definition with or without 18F FDG PET CT fusion in dosimetric planning for non-small cell lung cancer (NSCLC): Primary analysis of Radiation Therapy Oncology Group (RTOG) 0515. Int J Radiat Oncol Biol Phys. 2012;82(1):435–41.

6. Abramyuk A, Tokalov S, Zophel K, Koch A, Lazanyi KS, Gill-ham C, et al. Is pre-therapeutical FDG- 18F FDG PET CT capable to detect high risk tumor subvolumes responsible for local failure in non-small cell lung cancer? Radiother Oncol. 2009;91(3):399–404.

7. Toloza EM, Harpole L, McCrory DC. Noninvasive staging of non-small cell lung cancer: a review of the current evidence. Chest. 2003;123(1 Suppl):137S–46.

8. MacManus MP, Hicks RJ, Matthews JP, Hogg A, McKenzie AF, Wirth A, et al. High rate of detection of unsuspected distant metastases by PET in apparent stage III non-small-cell lung cancer: implications for radical radiation therapy. Int J Radiat Oncol Biol Phys. 2001;50(2):287–93.

9. Vanuystel LJ, Vansteenkiste JF, Sroobants SG, De Leyn PR, De Wever W, Verbeken EK, et al. The impact of 18 F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) lymph node staging on the radiation treatment volumes in patients with non-small cell lung cancer. Radiother Oncol. 2000;55(3):317–24.

10. Deniaud-Alexandre E, Touboul E, Lerouge D, Grahek D, Foulquier JN, Petegnief Y, et al. Impact of computed tomography and 18F-deoxyglucose coincidence detection emission tomography image fusion for optimization of conformal radiotherapy in non-small-cell lung cancer. Int J Radiat Oncol Biol Phys. 2005;63(5):1432–41.

11. Hicks RJ, Kalff V, MacManus MP, Ware RE, Hogg A, McKenzie AF, et al. 18F-FDG PET provides high-impact and powerful prognostic stratification in staging newly diagnosed non–small cell lung cancer. J Nucl Med. 2001;42(11):1596–604.

12. Nestle U, Walter K, Schmidt S, Licht N, Nieder C, Motaref B, et al. 18F-deoxyglucose positron emission tomograpy (FDG-PET) for the planning of radiotherapy in lung cancer: high impact in patients with atelectasis. Int J Radiat Oncol Biol Phys.1999;44(3):593–7.

13. Kiffer JD, Berlangieri SU, Scott AM, Quong G, Feigen M, Schumer W, et al. The contribution of 18F-fluoro- 2-deoxy-glucose positron emission tomography imaging to radiotherapy planning in lung cancer. Lung Cancer. 1998;19(3):167-77.

14. Van Der Wel A, Nijsten S, Hochstenbag M, Lamers R, Boersma L, Wanders R, et al. Increased therapeutic ratio by 18FDG-PET-CTplanning in patients with clinical CTstageN2/N3M0 non-small cell lung cancer: a modelling study. Int J Radiat Oncol Biol Phys. 2005;61(3):648–55.

15. Yin LJ, Yu XB, Ren YG, Gu GH, Ding TG, Lu Z. Utilization of PET-CT in target volume delineation for three-dimensional conformal radiotherapy in patients with non-small cell lung cancer and atelectasis. Multidiscip Respir Med. 2013;8(1):21.