Original research

EJNMMI Research

, 2:56

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

Assessment of tumour size in PET/CT lung cancer studies: PET- and CT-based methods compared to pathology

  • Patsuree CheebsumonAffiliated withDepartment of Radiology & Nuclear Medicine, VU University Medical Center
  • , Ronald BoellaardAffiliated withDepartment of Radiology & Nuclear Medicine, VU University Medical Center
  • , Dirk de RuysscherAffiliated withDepartment of Radiation Oncology (Maastro Clinic), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center
  • , Wouter van ElmptAffiliated withDepartment of Radiation Oncology (Maastro Clinic), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center
  • , Angela van BaardwijkAffiliated withDepartment of Radiation Oncology (Maastro Clinic), GROW School for Oncology and Developmental Biology, Maastricht University Medical Center
  • , Maqsood YaqubAffiliated withDepartment of Radiology & Nuclear Medicine, VU University Medical Center
  • , Otto S HoekstraAffiliated withDepartment of Radiology & Nuclear Medicine, VU University Medical Center
  • , Emile FI ComansAffiliated withDepartment of Radiology & Nuclear Medicine, VU University Medical Center
  • , Adriaan A LammertsmaAffiliated withDepartment of Radiology & Nuclear Medicine, VU University Medical Center
    • , Floris HP van VeldenAffiliated withDepartment of Radiology & Nuclear Medicine, VU University Medical Center Email author 

Abstract

Background

Positron emission tomography (PET) may be useful for defining the gross tumour volume for radiation treatment planning and for response monitoring of non-small cell lung cancer (NSCLC) patients. The purpose of this study was to compare tumour sizes obtained from CT- and various more commonly available PET-based tumour delineation methods to pathology findings.

Methods

Retrospective non-respiratory gated whole body [18F]-fluoro-2-deoxy-D-glucose PET/CT studies from 19 NSCLC patients were used. Several (semi-)automatic PET-based tumour delineation methods and manual CT-based delineation were used to assess the maximum tumour diameter.

Results

50%, adaptive 41% threshold-based and contrast-oriented delineation methods showed good agreement with pathology after removing two outliers (R2=0.82). An absolute SUV threshold of 2.5 also showed a good agreement with pathology after the removal of 5 outliers (R2: 0.79), but showed a significant overestimation in the maximum diameter (19.8 mm, p<0.05). Adaptive 50%, relative threshold level and gradient-based methods did not show any outliers, provided only small, non-significant differences in maximum tumour diameter (<4.7 mm, p>0.10), and showed fair correlation (R2>0.62) with pathology. Although adaptive 70% threshold-based methods showed underestimation compared to pathology (36%), it provided the best precision (SD: 14%) together with good correlation (R2=0.81). Good correlation between CT delineation and pathology was observed (R2=0.77). However, CT delineation showed a significant overestimation compared with pathology (3.8 mm, p<0.05).

Conclusions

PET-based tumour delineation methods provided tumour sizes in agreement with pathology and may therefore be useful to define the (metabolically most) active part of the tumour for radiotherapy and response monitoring purposes.

Keywords

Tumour delineation Tumour diameter FDG PET Non-small cell lung cancer