The accuracy of target delineation in laryngeal and hypopharyngeal cancer

Abstract

background and purpose. To determine the spatial correspondence between the gross tumor volume (GTV) delineated on computer tomography (CT) and the actual tumor on histopathology. Material and methods. Sixteen patients with T3 or T4 laryngeal or hypopharyngeal cancer underwent a CT scan before total laryngectomy. The GTV was delineated on CT by three independent observers and by consensus between the three observers. After surgery, whole-mount hematoxylin-eosin stained (H&E) sections were obtained. One pathologist delineated the tumor in the H&E sections (tumor H&E ). The reconstructed specimen was registered to the CT scan in order to compare the GTV to the tumor H&E in three dimensions. The overlap between the GTV and the tumor H&E was calculated and the distance between the volumes was determined. results. Tumor tissue was delineated in 203 of 516 H&E sections. For 14 patients a detailed analysis could be performed. The GTV volume was on average 1.7 times larger than the volume of the tumor H&E . The mean coverage of the tumor H&E by the consensus GTV was 88%. Tumor H&E tissue was found at 1.6 mm to 12.9 mm distance outside the GTV depending on observer and patient. conclusions. GTVs delineated on CT for laryngeal and hypopharyngeal cancer were 1.7 times larger than the tumor. Complete coverage of the tumor by the GTV was, however, not obtained.

CT-based volumetric tumor growth velocity: A novel imaging prognostic indicator in oropharyngeal cancer patients receiving radiotherapy

“…2,7,21,22 Recently, Caldas-Magalhaes et al demonstrated that GTVs delineated on CT for laryngeal and hypopharyngeal cancer were 1.7 times larger than the tumor measured on the Hematoxylin-eosin stained pathological sections of the same tumor after surgical resection and registration the respective CT delineations. 23 Also, the first scan utilized could be acquired at an outside hospital with different scanner and different slice thickness than the second scan, which was always done at MD Anderson. This difference may result in error in estimation of comparative tumor volumes.…”

Validated guidelines for tumor delineation on magnetic resonance imaging for laryngeal and hypopharyngeal cancer

“…Target delineation, however, is one of the largest sources of uncertainty in head-and-neck cancer radiotherapy [1]. Even with the introduction of new imaging techniques the interobserver variability remains relatively large [2][3][4][5]. For an accurate definition of the target volume, validation of gross tumor volume (GTV) delineation is fundamental.…”

“…For this validation, histopathology is the gold standard. However, this validation is a complex procedure and few studies have been performed for head-and-neck cancer [5][6][7]. For radiotherapy purposes, a detailed comparison of histopathology and imaging is required to validate the actual size, shape and location of the tumor.…”

“…Magnetic resonance imaging (MRI) is gaining ground in radiation oncology as availability and image quality have been improved dramatically [7,8]. Several studies [2,3,5,[9][10][11] have been performed, using various imaging modalities, to determine the agreement among observers when delineating the GTV in head-and-neck cancer. Studies in which CT was compared to MRI demonstrated contradictory results concerning the added value of MRI based on the inter-observer variation [3,4,11].…”

Technical Note: Diffusion‐weighted MRI with minimal distortion in head‐and‐neck radiotherapy using a turbo spin echo acquisition method

“…Target volumes determined on CT and MRI are largely overestimated as shown in pathological validation studies. 1,2 Diffusion-weighted (DW) MRI is a functional imaging technique that provides information on the local mobility of water in tissue. Dense tissues with an increased cellularity, such as glandular and nodal structures or tumors, will restrict the motion of water and show high contrast with surrounding tissue.…”