title: Feasibility of pathology-correlated lung imaging for accurate target definition of lung tumors.
abstract: OBJECTIVE
  To accurately define the gross tumor volume (GTV) and clinical target volume (GTV plus microscopic disease spread) for radiotherapy, the pretreatment imaging findings should be correlated with the histopathologic findings. In this pilot study, we investigated the feasibility of pathology-correlated imaging for lung tumors, taking into account lung deformations after surgery.
  
  
  METHODS
  High-resolution multislice computed tomography (CT) and positron emission tomography (PET) scans were obtained for 5 patients who had non-small-cell lung cancer (NSCLC) before lobectomy. At the pathologic examination, the involved lung lobes were inflated with formalin, sectioned in parallel slices, and photographed, and microscopic sections were obtained. The GTVs were delineated for CT and autocontoured at the 42% PET level, and both were compared with the histopathologic volumes. The CT data were subsequently reformatted in the direction of the macroscopic sections, and the corresponding fiducial points in both images were compared. Hence, the lung deformations were determined to correct the distances of microscopic spread.
  
  
  RESULTS
  In 4 of 5 patients, the GTV(CT) was, on average, 4 cm(3) ( approximately 53%) too large. In contrast, for 1 patient (with lymphangitis carcinomatosa), the GTV(CT) was 16 cm(3) ( approximately 40%) too small. The GTV(PET) was too small for the same patient. Regarding deformations, the volume of the well-inflated lung lobes on pathologic examination was still, on average, only 50% of the lobe volume on CT. Consequently, the observed average maximal distance of microscopic spread (5 mm) might, in vivo, be as large as 9 mm.
  
  
  CONCLUSIONS
  Our results have shown that pathology-correlated lung imaging is feasible and can be used to improve target definition. Ignoring deformations of the lung might result in underestimation of the microscopic spread.
authors: Department of Radiotherapy, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands. j.stroom@nki.nl
authors: Joep
authors: J
authors: Stroom
authors: Hans
authors: H
authors: Blaauwgeers
authors: Angela
authors: A
authors: van Baardwijk
authors: Liesbeth
authors: L
authors: Boersma
authors: Joos
authors: J
authors: Lebesque
authors: Jacqueline
authors: J
authors: Theuws
authors: Robert-Jan
authors: RJ
authors: van Suylen
authors: Houke
authors: H
authors: Klomp
authors: Koen
authors: K
authors: Liesker
authors: Renée
authors: R
authors: van Pel
authors: Christian
authors: C
authors: Siedschlag
authors: Kenneth
authors: K
authors: Gilhuijs
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000473:pathology; D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000473:pathology; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008168:Lung / Q000601:surgery; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D049268:Positron-Emission Tomography; D036542:Tomography, Spiral Computed; D047368:Tumor Burden