For laryngohypopharyngeal tumors, 45-52% target volume reduction compared with CTV is achievable when modality-specific CTV margins are used. PET-based CTVs were significantly smaller compared to CT- and MRI-based CTVs.

Background: Validation of magnetic resonance imaging (MRI) and development of guidelines for the delineation of the gross tumor volume (GTV) is of utmost importance to benefit from the visibility of anatomical details on MR images and to achieve an accurate GTV delineation. In the ideal situation, the GTV delineation corresponds to the histopathologically determined 'true tumor volume'. Consequently, we developed guidelines for GTV delineation of laryngeal and hypopharyngeal tumors on MRI and determined the accuracy of the resulting delineation of the tumor outline on histopathology as gold standard. Material and methods: Twenty-seven patients with T3 or T4 laryngeal/hypopharyngeal cancer underwent a MRI scan before laryngectomy. Hematoxylin and eosin sections were obtained from surgical specimens and tumor was delineated by one pathologist. GTV was delineated on MR images by three independent observers in two sessions. The first session (del1) was performed according to clinical practice. In the second session (del2) guidelines were used. The reconstructed specimen was registered to the MR images for comparison of the delineated GTVs to the tumor on histopathology. Volumes and overlap parameters were analyzed. A target margin needed to assure tumor coverage was determined. Results: The median GTVs (del1: 19.4 cm 3 , del2: 15.8 cm 3 ) were larger than the tumor volume on pathology (10.5 cm 3 ). Comparable target margins were needed for both delineation sessions to assure tumor coverage. By adding these margins to the GTVs, the target volumes for del1 (median: 81.3 cm 3 ) were significantly larger than for del2 (median: 64.2 cm 3 ) (p 0.0001) with similar tumor coverage. Conclusions: In clinical radiotherapy practice, the delineated GTV on MRI is twice as large as the tumor volume. Validated delineation guidelines lead to a significant decrease in the overestimation of the tumor volume.

BackgroundGTV delineation is the first crucial step in radiotherapy and requires high accuracy, especially with the growing use of highly conformal and adaptive radiotherapy techniques. If GTV delineations of observers concord, they are considered to be of high accuracy.The aim of the study is to determine the interobserver agreement for GTV delineations of supraglottic laryngeal carcinoma on CT and on CT combined with MR-images and to determine the effect of adding MR images to CT-based delineation on the delineated volume and the interobserver agreement.MethodsTwenty patients with biopsy proven T1-T4 supraglottic laryngeal cancer, treated with curative intent were included. For all patients a contrast enhanced planning CT and a 1.5-T MRI with gadolinium were acquired in the same head-and-shoulder mask for fixation as used during treatment. For MRI, a two element surface coil was used as a receiver coil. Three dedicated observers independently delineated the GTV on CT. After an interval of 2 weeks, a set of co-registered CT and MR-images was provided to delineate the GTV on CT. Common volumes (C) and encompassing volumes (E) were calculated and C/E ratios were determined for each pair of observers. The conformity index general (CIgen) was used to quantify the interobserver agreement. Results: In general, a large variation in interobserver agreement was found for CT (range: 0.29-0.77) as well as for CT-MR delineations (range: 0.17-0.80). The mean CIgen for CT (0.61) was larger compared to CT-MR (0.57) (p = 0.032). Mean GTV volume delineated on CT-MR (6.6 cm3) was larger compared to CT (5.6 cm3) (p = 0.002).ConclusionDelineation on CT with co-registered MR-images resulted in a larger mean GTV volume and in a decrease in interobserver agreement compared to CT only delineation for supraglottic laryngeal carcinoma.Electronic supplementary materialThe online version of this article (doi:10.1186/s13014-014-0321-4) contains supplementary material, which is available to authorized users.

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.

ObjectiveStaging of laryngeal cancer largely depends on cartilage invasion. Presence of cartilage invasion affects treatment choice and prognosis. On MRI and contrast‐enhanced CT (CECT) it may be challenging to differentiate cartilage invasion from inflammation. The purpose of this study is to compare the diagnostic properties of dynamic contrast‐enhanced CT (DCECT) and CECT for visual detection of cartilage invasion in laryngeal cancer.Study DesignProspective cohort study.MethodsPatients with T3 or T4 laryngeal squamous cell carcinoma treated with total laryngectomy were evaluated using 0.625 mm slice CT. DCECT derived permeability and blood volume maps and CECT images were visually evaluated for the presence of invasion of the cartilaginous T‐stage subsites of laryngeal cancer, by detecting continuity with the tumor‐bulk of increased permeability, increased blood volume, and enhancement. Histological evaluation of the surgical total laryngectomy specimen served as the gold standard. Sensitivity, specificity, negative predictive value, and positive predictive value were calculated and compared using the McNemar and Chi‐squared test.ResultsFrom 14 included patients, a total of 462 subsites were available for T‐stage analysis, of which 84 were cartilage. The median time between CT imaging and total laryngectomy was 1 day (range 1–34 days). There was no significant difference in the detection of cartilage invasion between DCECT and CECT. The sensitivity of CECT was better for all subsites combined (0.85 vs. 0.75; p < 0.01).ConclusionDCECT does not improve visual detection of cartilage invasion in T3 and T4 laryngeal cancer compared to CECT.Level of Evidence2b, individual cohort study.