title: PET-based delineation of tumour volumes in lung cancer: comparison with pathological findings.
abstract: OBJECTIVE
  The objective of the study was to validate an adaptive, contrast-oriented thresholding algorithm (COA) for tumour delineation in (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for non-small cell lung cancer (NSCLC) in comparison with pathological findings. The impact of tumour localization, tumour size and uptake heterogeneity on PET delineation results was also investigated.
  
  
  METHODS
  PET tumour delineation by COA was compared with both CT delineation and pathological findings in 15 patients to investigate its validity. Correlations between anatomical volume, metabolic volume and the pathology reference as well as between the corresponding maximal diameters were determined. Differences between PET delineations and pathological results were investigated with respect to tumour localization and uptake heterogeneity.
  
  
  RESULTS
  The delineated volumes and maximal diameters measured on PET and CT images significantly correlated with the pathology reference (both r > 0.95, p < 0.0001). Both PET and CT contours resulted in overestimation of the pathological volume (PET 32.5 ± 26.5%, CT 46.6 ± 27.4%). CT volumes were larger than those delineated on PET images (CT 60.6 ± 86.3 ml, PET 48.3 ± 61.7 ml). Maximal tumour diameters were similar for PET and CT (51.4 ± 19.8 mm for CT versus 53.4 ± 19.1 mm for PET), slightly overestimating the pathological reference (mean difference CT 4.3 ± 3.2 mm, PET 6.2 ± 5.1 mm). PET volumes of lung tumours located in the lower lobe were significantly different from those determined from pathology (p = 0.037), whereas no significant differences were observed for tumours located in the upper lobe (p = 0.066). Only minor correlation was found between pathological tumour size and PET heterogeneity (r = -0.24).
  
  
  CONCLUSIONS
  PET tumour delineation by COA showed a good correlation with pathological findings. Tumour localization had an influence on PET delineation results. The impact of tracer uptake heterogeneity on PET delineation should be considered carefully and individually in each patient. Altogether, PET tumour delineation by COA for NSCLC patients is feasible and reliable with the potential for routine clinical application.
authors: Department of Nuclear Medicine, Saarland University Medical Center, 66421 Homburg, Germany. andrea.schaefer@uks.eu
authors: Andrea
authors: A
authors: Schaefer
authors: Yoo Jin
authors: YJ
authors: Kim
authors: Stephanie
authors: S
authors: Kremp
authors: Sebastian
authors: S
authors: Mai
authors: Jochen
authors: J
authors: Fleckenstein
authors: Hendrik
authors: H
authors: Bohnenberger
authors: Hans-Joachim
authors: HJ
authors: Schäfers
authors: Jan-Martin
authors: JM
authors: Kuhnigk
authors: Rainer M
authors: RM
authors: Bohle
authors: Christian
authors: C
authors: Rübe
authors: Carl-Martin
authors: CM
authors: Kirsch
authors: Aleksandar
authors: A
authors: Grgic
mesh_terms: D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D047368:Tumor Burden
chemical_list: D019788:Fluorodeoxyglucose F18
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