title: Validation of imaging with pathology in laryngeal cancer: accuracy of the registration methodology.
abstract: OBJECTIVE
  To investigate the feasibility and accuracy of an automated method to validate gross tumor volume (GTV) delineations with pathology in laryngeal and hypopharyngeal cancer.
  
  
  METHODS
  High-resolution computed tomography (CT(HR)), magnetic resonance imaging (MRI), and positron emission tomography (PET) scans were obtained from 10 patients before total laryngectomy. The GTV was delineated separately in each imaging modality. The laryngectomy specimen was sliced transversely in 3-mm-thick slices, and whole-mount hematoxylin-eosin stained (H&E) sections were obtained. A pathologist delineated tumor tissue in the H&E sections (GTV(PATH)). An automatic three-dimensional (3D) reconstruction of the specimen was performed, and the CT(HR), MRI, and PET were semiautomatically and rigidly registered to the 3D specimen. The accuracy of the pathology-imaging registration and the specimen deformation and shrinkage were assessed. The tumor delineation inaccuracies were compared with the registration errors.
  
  
  RESULTS
  Good agreement was observed between anatomical landmarks in the 3D specimen and in the in vivo images. Limited deformations and shrinkage (3% ± 1%) were found inside the cartilage skeleton. The root mean squared error of the registration between the 3D specimen and the CT, MRI, and PET was on average 1.5, 3.0, and 3.3 mm, respectively, in the cartilage skeleton. The GTV(PATH) volume was 7.2 mL, on average. The GTVs based on CT, MRI, and PET generated a mean volume of 14.9, 18.3, and 9.8 mL and covered the GTV(PATH) by 85%, 88%, and 77%, respectively. The tumor delineation inaccuracies exceeded the registration error in all the imaging modalities.
  
  
  CONCLUSIONS
  Validation of GTV delineations with pathology is feasible with an average overall accuracy below 3.5 mm inside the laryngeal skeleton. The tumor delineation inaccuracies were larger than the registration error. Therefore, an accurate histological validation of anatomical and functional imaging techniques for GTV delineation is possible in laryngeal cancer patients.
authors: Department of Radiotherapy, University Medical Center Utrecht, The Netherlands. J.CaldasMagalhaes@umcutrecht.nl
authors: Joana
authors: J
authors: Caldas-Magalhaes
authors: Nicolien
authors: N
authors: Kasperts
authors: Nina
authors: N
authors: Kooij
authors: Cornelis A T
authors: CA
authors: van den Berg
authors: Chris H J
authors: CH
authors: Terhaard
authors: Cornelis P J
authors: CP
authors: Raaijmakers
authors: Marielle E P
authors: ME
authors: Philippens
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D059925:Anatomic Landmarks / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D005240:Feasibility Studies; D005260:Female; D016591:Histocytological Preparation Techniques / Q000379:methods; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007822:Laryngeal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D007825:Laryngectomy / Q000379:methods; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods; D047368:Tumor Burden