Interobserver Concordance Rate Research Articles

High interobserver and intraobserver reproducibility among pathologists assessing PD-L1 CPS across multiple indications.

A common concern among pathologists scoring PD-L1 immunohistochemical staining is interobserver and intraobserver variability. We assessed the interobserver and intraobserver reproducibility of PD-L1 scoring among trained pathologists using a combined positive score (CPS; tumour cell and tumour-associated immune cell staining). Data were collected for 2 years (2017-2019) from 456 pathologists worldwide. Digital training encompassed unique, tumour-specific training, and test sets. Samples were stained using PD-L1 IHC 22C3 pharmDx and evaluated at specific CPS cutoffs for gastric cancer (GC), cervical cancer (CC), urothelial cancer (UC), oesophageal cancer (OC), and head and neck squamous cell carcinoma (HNSCC). Pathologists underwent expert-to-peer training and scored 20 blinded samples on day 1 and 25 blinded samples on day 2 (including 15 of the day 1 samples). Interobserver and intraobserver reproducibility were assessed. For GC (120 observers) and CC (32 observers) samples assessed at CPS ≥1, average interobserver agreement was 91.5% and 91.0%, respectively, and average intraobserver agreement was 90.2% and 96.6%, respectively. For UC (139 observers) and OC (52 observers) samples measured at CPS ≥10, average interobserver agreement was 93.4% and 93.7%, respectively, and average intraobserver agreement was 92.0% and 92.5%, respectively. For HNSCC samples (113 observers), average interobserver agreement was 94.1% at CPS ≥1 and 86.5% at CPS ≥20; intraobserver agreement was 94.7% at CPS ≥1 and 90.5% at CPS ≥20. The consistently high interobserver and intraobserver concordance rates support the effectiveness of face-to-face training of many global pathologists for scoring PD-L1 CPS across multiple indications at several specific cutoffs.

Correlation and agreement between physical and ultrasound examination after a training session dedicated to the standardization of synovitis assessment in rheumatoid arthritis patients

ObjectivesAssessing disease activity in rheumatoid arthritis (RA) patients requires comprehensive quantification of tender and swollen joints. We aimed to evaluate the correlation and agreement between rheumatologists after a training session dedicated to the standardization of synovitis assessment and compare its performance with a reference imaging modality such as musculoskeletal ultrasonography (MSUS).MethodsIn this cross-sectional study, a total of 28 and 10 joints in RA patients were evaluated by physical examination and ultrasound (US), respectively. After participating in a training session, individual joint assessment for tenderness and swelling was performed by three rheumatologists. MSUS examination was performed separately by an experimented radiologist in a standardized manner, evaluating findings according to the Outcome Measures in Rheumatology Clinical Trial (OMERACT) guidelines.ResultsA total of 80 RA patients were included, with a mean Disease Activity Score based on 28 joints (DAS28)-ESR of 4.02. The interobserver overall agreement and concordance rate in a total of 2240 joints assessed was 81.7% (k = 0.449, p < 0.0001) for tender joints and 66% (k = 0.227, p < 0.0001) for swollen joints. The overall concordance rate was fair (Fleiss' kappa = 0.21, p = 0.027) with an overall agreement of 67.18% yet, more joints were found to be swollen by the US assessment, compared to the physical examination (43% vs 39%).ConclusionIn our study population, joint tenderness showed better interobserver agreement, correlation, and concordance rate than joint swelling. When comparing the US assessment to the physical examination, a fair overall concordance rate supports the need for the implementation of training sessions dedicated to standardization in rheumatology clinics.

Prognostic significance of nucleolar assessment in invasive breast cancer.

Nucleolar morphometric features have a potential role in the assessment of the aggressiveness of many cancers. However, the role of nucleoli in invasive breast cancer (BC) is still unclear. The aims of this study were to investigate the optimal method for scoring nucleoli in IBC and their prognostic significance, and to refine the grading of breast cancer (BC) by incorporating nucleolar score. Digital images acquired from haematoxylin and eosin-stained sections from a large BC cohort were divided into training (n=400) and validation (n=1200) sets for use in this study. Four different assessment methods were evaluated in the training set to identify the optimal method associated with the best performance and significant prognostic value. These were: (i) a modified Helpap method; (ii) counting prominent nucleoli (size ≥2.5µm) in 10 field views (FVs); (iii) counting prominent nucleoli in five FVs; and (iv) counting prominent nucleoli in one FV. The optimal method was applied to the validation set and to an external validation set, i.e. data from The Cancer Genome Atlas (n=743). Scoring prominent nucleoli in five FVs showed the highest interobserver concordance rate (intraclass correlation coefficient of 0.8) and a significant association with BC-specific survival (P<0.0001). A high nucleolar score was associated with younger age, larger tumour size, and higher grade. Incorporation of nucleolar score in the Nottingham grading system resulted in a higher significant association with survival than the conventional grade. Quantification of nucleolar prominence in five FVs is a cost-efficient and reproducible morphological feature that can predict BC behaviour and can provide an alternative to pleomorphism to improve BC grading performance.

Thymoma diagnosis and categorization in the current scenario: Morphological analysis based on interobserver variability.

BACKGROUND:Thymomas are not so common tumors that are encountered in day-to-day pathology reporting. The WHO system was proposed in 2015. Although, through its detailed reporting, the WHO elaborates all subtypes and morphological clinches to diagnosis, it was important to ascertain its reproducibility in our day-to-day reporting.AIMS:The aims of the study were (1) to study the interobserver agreement, concordance rates, and variability in the classification of a large number of thymomas received in our department as per the WHO 2015, (2) to correlate the WHO subtype with Masaoka–Koga stage, and (3) to study the variations in demography of thymomas in Indian patients as compared to those reported in the literature.SETTING AND DESIGN:This retrospective study was done at a tertiary care teaching hospital with huge surgical oncology patient load, also pertaining to the cardiothoracic surgeries. It is predominantly an interobserver agreement design to study the reproducibility of the WHO 2015 classification on thymic epithelial tumors.METHODS:Four pathologists have independently reviewed histopathology slides of 65 cases of thymomas and classified them into predefined categories. Kappa statistics was applied to the observations.RESULTS:There was a substantial interobserver agreement in overall classification of thymomas with a Cohen's kappa score of 0.66. A better score was achieved for the classification of Group B thymomas. The WHO subtypes correlate well with the Masaoka–Koga staging system, and this finding is statistically significant. This article also presents the clinical details of a large number of thymoma cases.CONCLUSION:The new WHO classification has good reproducibility among pathologists in thymoma reporting.

Pathological Tumor Regression Grade Classifications in Gastrointestinal Cancers: Role on Patients' Prognosis.

Preoperative chemotherapy or combined radiotherapy and chemotherapy (CRT), followed by surgery, represents the standard approach for locally advanced esophageal, gastric, and rectal carcinomas. To adequately evaluate the effects of neoadjuvant CRT in the resection specimens, several histopathologic tumor regression grade (TRG) scoring systems have been introduced into clinical practice. The primary goal of these TRG systems relies on a correct prognostic stratification of patients in the attempt to help clinical decision-making and influence surgical strategies, postoperative adjuvant therapies, and surveillance intensity. However, most TRG systems suffer from poor reproducibility and low interobserver concordance rates. Many efforts have been made in the identification of alternative, robust, simple, and universally accepted TRG scoring systems, which would help in the comparison of different treatment strategies and in the standardization of multimodal therapies. The aim of this review is to analyze the most commonly used TRG systems in gastrointestinal cancers highlighting their pitfalls and usefulness, depending on the tumor type.

Carabelli Trait in Australian Twins: Reliability and Validity of Different Scoring Systems

We assessed the intra- and inter-observer reliability of two methods of scoring or categorizing Carabelli trait in both primary and permanent dentitions (Hanihara, 1961; Dahlberg, 1963). By using dental casts obtained from twins, we also compared the expression of Carabelli trait within and between monozygotic (MZ) co-twins to clarify the ontogenetic processes leading to different forms of trait expression. While intra-observer concordance rates were generally good (70 - 90%), inter-observer concordance rates were poor (35 - 60%). This indicates that considerable caution is needed when comparing data for Carabelli trait derived from different samples by different researchers. By comparing categories or scores for Carabelli trait in both dentitions of MZ co-twins, we found inter-relationships between groove and cuspal forms of the feature. Although the Arizona State University system developed by Turner is commonly used nowadays to score the Carabelli trait, we would encourage researchers interested in clarifying genetic influences and ontogenetic processes in both dentitions to refer to the often over-looked plaque of Hanihara and also Dahlberg’s plaque P12B. This should improve the reliability and validity of data obtained by helping to clarify the inter-relationships between the different phenotypic expressions of Carabelli trait.

The updated grading system of prostate carcinoma: an inter-observer agreement study among general pathologists in an academic practice.

In 2016, the grading criteria for Gleason scoring (GS) have been updated in the WHO classification of tumors of the prostate, and a new set of grade groups (GG) was introduced. As the inter-observer discordance is a well-known concern in Gleason grading before the update and no reproducibility study testing the grade groups exists, we planned to evaluate the inter-observer agreement of the most updated grading system. Four pathologists assessed 126 cores of prostatic carcinoma, and Kappa (k) test was calculated. The agreements for both GS and GG were substantial (k = 0.753 and 0.752; respectively). Discerning GG 2 from 3 also attained reasonable outcome (k = 0.675). Based on our results, the updated grading system seems to be reproducible, with satisfactory inter-observer concordance rate.

Feasibility study in teledermatopathology: An examination of the histopathologic features of mycosis fungoides and spongiotic dermatitis.

Digital pathology offers numerous advantages, allowing remote information sharing using whole slide imaging (WSI) to digitize an entire glass slide (GS) at high resolution, creating a digital slide (DS). In this study, we examine the concordance in diagnoses made on 40 digital slides (DSs) vs traditional GSs in differentiating between spongiotic dermatitis (SD) and patch/plaque-stage mycosis fungoides (MF). Greater interobserver concordance rate in final diagnosis of SD vs MF was observed with the utilization of DS (86.7%) compared with the utilization of GS (80%). Intraobserver concordance rate between the diagnoses rendered by a particular dermatopathologist on GS and DS was 86.7%. For all histopathological criteria, a correlation in the magnitudes of interobserver vs intraobserver discordances suggests that discordance between glass vs digital evaluation of these criteria may be largely expected subjective read variation independent of the media. Discordance in identification of histopathological features did not have a statistically significant link to discordance in diagnosis for 7 out of the 8 features. The similarity between interobserver and intraobserver discordances suggests that WSI does not introduce additional barriers or variability to accurately identify histopathologic feature and to discriminate between MF and SD beyond interobserver variability.

Prospective comparison of gadoxetic acid-enhanced liver MRI and contrast-enhanced CT with histopathological correlation for preoperative detection of colorectal liver metastases following chemotherapy and potential impact on surgical plan

ObjectiveTo prospectively compare the diagnostic performance of gadoxetic acid-enhanced MRI (EOB-MRI) and contrast-enhanced CT (CECT) for preoperative detection of colorectal liver metastases (CRLM) following chemotherapy and to evaluate the potential change in the hepatic resection plan. Methods51 patients with CRLM treated with preoperative chemotherapy underwent liver imaging by EOB-MRI and CECT prospectively. Two independent blinded readers characterized hepatic lesions on each imaging modality using a 5-point scoring system. 41 patients underwent hepatic resection and histopathological evaluation. Results151 CRLM were confirmed by histology. EOB-MRI, compared to CECT, had significantly higher sensitivity in detection of CRLM ≤1.0 cm (86% vs. 45.5%; p < 0.001), significantly lower indeterminate lesions diagnosis (7% vs. 33%; p < 0.001) and significantly higher interobserver concordance rate in characterizing the lesions ≤1.0 cm (72% vs. 51%; p = 0.041). The higher yield of EOB-MRI could have changed the surgical plan in 45% of patients. ConclusionFollowing preoperative chemotherapy, EOB-MRI is superior to CECT in detection of small CRLM (≤1 cm) with significantly higher sensitivity and diagnostic confidence and interobserver concordance in lesion characterization. This improved diagnostic performance can alter the surgical plan in almost half of patients scheduled for liver resection.

Pathologists’ diagnosis of invasive melanoma and melanocytic proliferations: observer accuracy and reproducibility study

Objective To quantify the accuracy and reproducibility of pathologists’ diagnoses of melanocytic skin lesions.Design Observer accuracy and reproducibility study.Setting 10 US states.Participants Skin biopsy cases (n=240), grouped into sets of...

Counting invasive breast cancer cells in the HER2 silver in-situ hybridization test: how many cells are enough?

To evaluate the intraobserver and interobserver reproducibility of the HER2 in-situ hybridization (ISH) test in breast cancer by measuring the impact of counting different numbers of invasive cancer cells. A cohort of 101 primary invasive breast cancer cases were evaluated for HER2 gene amplification by silver ISH, and the concordance among four observers with different levels of experience, counting different numbers of invasive cancer cells, was determined. The evaluation of the samples included scoring 20 nuclei, in three different areas. The cases were scored twice, with a washout interval of at least 2 weeks. We observed an increase in the intraobserver concordance rate between the first and second evaluations with an increase in cell count. A count of 60 invasive cells was needed to obtain a concordance rate near 95% and an agreement rate greater than 0.80 by all observers. The interobserver concordance rate of the HER2 test also increased with the increase in cell count, reaching at least a 90% concordance rate with a count of 60 invasive cells. The median variability of both the HER2/CEP17 ratio and the average HER2 copy number between different evaluations decreased with the increase in cell count, being statistically higher in HER2-positive cases. The minimal cell number recommended in current guidelines should be raised to at least 40, and preferably 60, invasive cells. Moreover, cases with amplification levels close to the threshold should be subjected to a dual count from an experienced observer.

Can We Determine Sasang Constitutional Body Type Merely by Facial Inspection?

This study aimed to assess the inter-observer concordance rate of anthroscopic examination on facial features among experts in Sasang constitutional medicine (SCM) in order to evaluate the presence of statistical differences in facial structural characteristics among different body types of Sasang constitution (SC), and to develop an objective method for facial analysis for diagnosing SC types to prevent SCM experts from misdiagnosis by their perceptional errors about faces. This was a double-blinded cross-sectional study conducted on 174 people's faces. Ten SCM experts participated in this study. Frontal and lateral photographs of subjects were standardized and displayed to 10 SCM experts for diagnosing the SC type by anthroscopic examination alone (experiment 1). The subjects' faces were analyzed by photogrammetric method to investigate the presence of any typical structural characteristics of the faces to differentiate SC type (experiment 2). Comparing subjects' SC type with anthroscopic diagnosis by 10 SCM experts, the inter-observer concordance rates were measured (experiment 1). Using photogrammetric facial analysis, a multinomial logistic model was made for analyzing the correlation of SC type and subjects' facial structural configuration (experiment 2). The inter-observer concordance rate of anthroscopic examination was 2.9% in experiment 1. Using a multinomial logistic fitting model, the predicted probability for determining SC type was 52.8-57.6% in experiment 2 (p < 0.05). Prototype composite faces were also created from photographs of subjects who received the same SC type from the SCM experts. As SC type cannot be precisely diagnosed using anthroscopic examination alone, SCM needs a definitive objective and scientific diagnosing method to be a scientifically verified alternative medicine and be globalized in future.

Intra and interobserver concordance between the different classifications used in Legg–Calvé–Perthes disease

ObjectiveThe aim of this study was to determine the intra and interobserver concordance rates of the Waldenström, Catterall and Herring classifications for Legg–Calvé–Perthes disease. MethodsOne hundred radiographs of the pelvis in anteroposterior and Lauenstein views, from patients with this disease, were selected. The radiographs were classified by four physicians with different levels of experience who had previously been given guidance regarding the classifications used, in order to minimize any bias of interpretation. The radiographs were examined by the same observers at two different times in order to evaluate the intra and interobserver concordance. Reproducibility was assessed using the kappa index. ResultsThe concordance analysis was stratified into levels (poor, slight, fair, moderate, good and excellent). The intraobserver analysis showed, for the Waldenström classification, moderate concordance for three examiners and fair for one; for Herring, excellent for one examiner and good for three; and for Catterall, good for all the examiners. The interobserver analysis showed: for the three classification systems, no situations of excellent concordance; for Waldenström, four situations of fair concordance, one moderate and one slight; for Herring, four situations of moderate concordance, one good and one fair; and for Catterall, four situations of moderate concordance and two fair. ConclusionThe classifications studied are the ones most used for guiding the treatment for Legg–Calvé–Perthes disease, but the degree of intra and interobserver concordance is far from ideal. Complementary staging systems need to be taken into consideration, so that there can be greater certainty regarding the treatment.

Concordância intra e interobservadores das diferentes classificações usadas na doença de Legg‐Calvé‐Perthes

ObjectiveThe aim of this study was to determine the intra and interobserver concordance rates of the Waldenström, Catterall and Herring classifications for Legg‐Calvé‐Perthes disease. MethodsOne hundred radiographs of the pelvis in anteroposterior and Lauenstein views, from patients with this disease, were selected. The radiographs were classified by four physicians with different levels of experience who had previously been given guidance regarding the classifications used, in order to minimize any bias of interpretation. The radiographs were examined by the same observers at two different times in order to evaluate the intra and interobserver concordance. Reproducibility was assessed using the kappa index. ResultsThe concordance analysis was stratified into levels (poor, slight, fair, moderate, good and excellent). The intraobserver analysis showed, for the Waldenström classification, moderate concordance for three examiners and fair for one; for Herring, excellent for one examiner and good for three; and for Catterall, good for all the examiners. The interobserver analysis showed: for the three classification systems, no situations of excellent concordance; for Waldenström, four situations of fair concordance, one moderate and one slight; for Herring, four situations of moderate concordance, one good and one fair; and for Catterall, four situations of moderate concordance and two fair. ConclusionThe classifications studied are the ones most used for guiding the treatment for Legg‐Calvé‐Perthes disease, but the degree of intra and interobserver concordance is far from ideal. Complementary staging systems need to be taken into consideration, so that there can be greater certainty regarding the treatment.

Development of an easy method to test for HER2 in breast cancer using dual-color in situ hybridization.

Although human epidermal growth factor receptor 2 (HER2) is a significant clinical biomarker for breast cancer, the HER2 testing involves a complicated evaluation process. We devised an easy method for HER2 gene testing and investigated its utility. HER2 testing was performed by immunohistochemistry (IHC) and dual-color in situ hybridization (DISH) on surgical specimens from 50 patients with invasive breast cancer. DISH was evaluated by two methods. One was the DISH count method in which the HER2 and CEP17 signals were counted and the HER2/CEP17 signal ratio was calculated. The other was the DISH-easy method in which pathologists only observed slices without counting the signals. The DISH-easy method was performed by two pathologists. We analyzed the correlations between the DISH-easy method and the DISH count method by each pathologist and calculated the inter-observer concordance rate of the DISH-easy method. The results from two pathologists using the DISH-easy method corresponded to the IHC results (P < 0.01) and the DISH count method results (P < 0.01). All cases determined to be negative using the DISH-easy method were also negative via the DISH count method with a corresponding rate of 100 % for both pathologist A (34/34) and B (32/32). Most of the results for the positive cases also corresponded; the correspondence rate of pathologist A was 100 % (8/8) and 89 % for B (8/9). The inter-observer concordance rate was 81 % (κ = 0.65). The DISH-easy method is simple and useful for HER2 testing regardless of proficiency of the evaluators.

Prevalence and patterning of maxillary premolar accessory ridges (MxPARs) in several human populations

We present new data on the prevalence and patterning of the maxillary premolar accessory ridge (MxPAR), a common but understudied morphological dental trait that is expressed as a linear elevation extending from the buccal cusp ridge to the medial sulcus of maxillary premolar teeth. A total of 579 sets of dental casts, representing six ethnic groups, were scored using the five-grade system proposed by Burnett et al. (2010). The frequency and distribution of the MxPAR were determined by tooth type, sex, side, locus and ethnicity, and the applicability of the scoring system was assessed. The MxPAR was found in approximately two-thirds of premolar teeth, more often on second than first premolars, and more often on the distal aspect of the occlusal surface than the mesial. There was some evidence that more pronounced forms of the feature occurred more often in males than females, and that there may be some directionality in its expression between sides. Variation was also noted in the frequency of occurrence and degree of expression of the MxPAR between ethnic groups. Intra- and inter-observer concordance rates for scoring the MxPAR were low, confirming that it was difficult to score the trait identically on two different occasions. Our findings have clarified the distribution of the MxPAR within the dentition and between ethnic groups, and highlighted the need for researchers to carry out thorough replicability studies and to decide on an appropriate breakpoint for determining presence or absence of this feature before embarking on genetic studies or bio-distance analyses.

Double reading for gross tumor volume assessment in radiotherapy planning

Background/Objective: The precise definition of the gross tumor volume (GTV) that takes into account intra- and interobserver variability is necessary for high-precision radiotherapy (RT) techniques. The purpose of this study was to demonstrate the practical GTV assessment by a “double reading” approach. Methods: Pretreatment magnetic resonance (MR) imaging, including the post-contrast 3D magnetization-prepared rapid-gradient echo (MP-RAGE) sequence (section thickness 1.0 mm) was performed on a 3T superconducting imager in 50 patients with glioblastoma. MR images were transferred to a RT planning system (RTPS) that provides many opportunities for GTV contouring, e.g., at diagnosis, surgical navigation, and RT deliberations. Independent 2 observers preliminarily contoured the GTV on MR images. After planning-CT scanning, CT images with a 1.0 mm slice interval were transferred to the RTPS, registered with the diagnostic images, and then the preliminarily-contoured strictures were copied onto the CT images and used for GTV assessment. The practical GTV on the planning CT was determined by integrating the interpretations and adding information on postoperative changes. The interobserver variability in GTV contouring was assessed by Bland-Altman analysis and the concordance index. Results: There was substantial interobserver variability in GTV contouring (95% limits of agreement: -29.4%, 16.8%). The mean interobserver concordance rate for the GTV was 82.1% (range 56.5-91.2%). The practical GTVs were significantly larger than the preliminarily-contoured GTVs by both observers ( p < 0.01). Conclusions: Considering interobserver variability, “double reading” is necessary for practical GTV assessment. This approach for volume assessment may facilitate the standardization of treatments, not only of RT but also of surgery and chemotherapy.

Peritubular capillary basement membrane changes in chronic renal allograft rejection

Marked peritubular capillary basement membrane (PTCBM) multilayering, the ultrastructural feature of chronic antibody-mediated rejection (ABMR) of kidney allografts, was found to correspond histologically to PTCs with thickened BMs; such PTCs have been suggested as a novel histological marker of chronic rejection. We investigated whether scoring of PTCBM thickening can substitute the ultrastructural search for PTCBM multilayering. The thickening was graded in PAS- and Jones-stained sections in 110 biopsies from recipients with a late dysfunction, all examined ultrastructurally for transplant capillaropathy (≥3PTCs with ≥5BM layers). Grade 0 indicated no thickening. Grade 1 and grade 2 were assigned when the PTCBMs were as thick as or thicker than those of the non-atrophic tubules, and duplication/chain-like lamination of the PTCBM was noted in ≤3 or ≥4 high-power fields, respectively. The series was enrolled in subgroups of those with and those without histopathological lesions of chronic rejection. Fifty-six biopsies displayed lesions of chronic ABMR. Transplant capillaropathy was demonstrated in 40 biopsies. Grade 2 thickening furnished a substantial interobserver concordance rate (κ = 0.803) and correlated with the transplant capillaropathy. Jones staining performed somewhat better in scoring than PAS staining. Grade 2 thickening was verified in 35 biopsies involving chronic ABMR, and in one control biopsy (sensitivity 61.4%, specificity 0.98). Grade 1 thickening was not suggestive of chronic ABMR at all. In conclusion, grade 2 thickening can be regarded as the histopathological lesion of chronic ABMR; however, electron microscopy remains the gold standard in the assessment of PTCBM changes.

Validation of the National Institutes of Health Stroke Scale, Modified Rankin Scale and Barthel Index in Brazil: The Role of Cultural Adaptation and Structured Interviewing

Background: We aimed to validate three widely used scales in stroke research in a multiethnic Brazilian population. Methods: The National Institutes of Health Stroke Scale (NIHSS), modified Rankin Scale (mRS) and Barthel Index (BI) were translated, culturally adapted and applied by two independent investigators. The mRS was applied with or without a previously validated structured interview. Interobserver agreement (kappa statistics) and intraclass correlation coefficients were calculated. Results: 84 patients underwent mRS (56 with and 28 without a structured interview), 57 BI and 62 NIHSS scoring. Intraclass correlation coefficient was 0.902 for NIHSS and 0.967 for BI. For BI, interobserver agreement was good (kappa = 0.70). For mRS, the structured interview improved interobserver agreement (kappa = 0.34 without a structured interview; 0.75 with a structured interview). Conclusion: The NIHSS, BI and mRS show good validity when translated and culturally adapted. Using a structured interview for the mRS improves interobserver concordance rates.

Impact of fdg-pet/ct fused imaging on tumor volume assessment of head-and-neck squamous cell carcinoma: intermethod and interobserver variations

Although gross tumor volume (GTV) at the primary site can predict local control of head-and-neck squamous cell carcinoma (SCC) in patients who are treated with organ-preservation therapy, GTV assessment does not eliminate substantial interobserver variation. To evaluate whether F-18-fluorodeoxyglucose positron emission tomography (FDG-PET)/computed tomography (CT) fused imaging provides additional information for GTV assessment. We obtained FDG-PET/CT fused images on 20 patients with head-and-neck SCC. All had undergone preoperative conventional workup, including contrast-enhanced CT and magnetic resonance imaging (MRI). The GTV of the primary tumors was designed by two independent observers who used routine clinical data. Observer A was a radiologist and observer B a radiation oncologist. GTV1 and GTV2 were designed without and with FDG-PET/CT, respectively. For geometric interobserver comparison, we calculated the concordance rate as the ratio of the intersection (AxB) of the GTVs to their union (AxB). Intermethod (GTV1 vs. GTV2) and interobserver (A vs. B) differences in the GTVs were assessed by Bland-Altman analysis and the Spearman rank-correlation test. The interobserver concordance rates for GTV1 and GTV2 were compared using a two-tailed paired-samples t test. On FDG-PET/CT, all primary tumors were visualized. There was no systemic trend for a volume difference between GTV1 and GTV2. Although the 95% limits of agreement were wider for interobserver than intermethod differences, the 95% limits of interobserver agreement were narrower for GTV2 than GTV1. The mean interobserver concordance rate for GTV2 was higher than for GTV1 (54.5% vs. 39.1%, P=0.0002). FDG-PET/CT is a useful modality for consistent GTV assessment, which should not be used as a single modality but rather to obtain supplemental information in patients with head-and-neck SCC.