Selection and delineation of lymph node target volumes in head and neck conformal radiotherapy. Proposal for standardizing terminology and procedure based on the surgical experience.

The increasing use of 3D treatment planning in head and neck radiation oncology has created an urgent need for new guidelines for the selection and the delineation of the neck node areas to be included in the clinical target volume. Surgical literature has provided us with valuable information on the extent of pathological nodal involvement in the neck as a function of the primary tumor site. In addition, few clinical series have also reported information on radiological nodal involvement in those areas not commonly included in radical neck dissection. Taking all these data together, guidelines for the selection of the node levels to be irradiated for the major head and neck sites could be proposed. To fill the missing link between these guidelines and the 3D treatment planning, recommendations for the delineation of these node levels (levels I-VI and retropharyngeal) on CT (or MRI) slices have been proposed using the guidelines outlined by the Committee for Head and Neck Surgery and Oncology of the American Academy for Otolarynology-Head and Neck Surgery. These guidelines were adapted to take into account specific radiological landmarks more easily identified on CT or MRI slices than in the operating field.     

Délinéation des adénopathies et aires ganglionnaires pour les cancers de la sphère ORL

The aim of this article is to present the determination and delineation of nodal target volumes for head and neck cancers treated with intensity-modulated radiotherapy. The delineation on computerized tomography scanner (CT scan) requires a precise methodology. Different elements are necessary: clinical examination, diagram of the initially involved lymph nodes, surgical and pathological reports and medical imagings (CT scan, magnetic resonance imaging and fluorodeoxyglucose positron emission tomography). The different clinical target volumes are approached and the concept of selectivity of neck nodal targets is specified according to current literature.     

Clinical target volume delineation including elective nodal irradiation in preoperative and definitive radiotherapy of pancreatic cancer

ABSTRACT: BACKGROUND: Radiotherapy is widely used in the treatment of pancreatic cancer. Currently, recommendation has been given for the delineation of the clinical target volume (CTV) in adjuvant radiotherapy. Based on recently reviewed pathologic data, the aim of this study is to propose criteria for the CTV definition and delineation including elective nodal irradiation (ENI) in the preoperative and definitive treatment of pancreatic cancer. METHODS: The anatomical structures of interest, as well as the abdominal vasculature were identified on intravenous contrast-enhanced CT scans of two different patients with pancreatic cancer of the head and the body. To delineate the lymph node area, a margin of 10 mm was added to the arteries. RESULTS: We proposed a set of guidelines for elective treatment of high-risk nodal areas and CTV delineation. Reference CT images were provided. CONCLUSIONS: The proposed guidelines could be used for preoperative or definitive radiotherapy (RT) for carcinoma of the head and body of the pancreas. Further clinical investigations are needed to validate the defined CTVs.     

218例鼻咽癌颈淋巴结转移规律的影像学分析

背景与目的：鼻咽癌调强放射治疗要求在cT图像上准确划分需要照射的淋巴结和相应的亚临床靶区,前提就是总结出鼻咽癌淋巴结转移的影像学分布规律。本研究的目的是分析鼻咽癌颈淋巴结转移的影像学规律。方法：2003年7月至2003年11月,259例鼻咽癌患者在我院接受了放射治疗。所有患者治疗前接受横断面CT增强扫描,扫描范围是颅底至锁骨。由放射诊断医生和肿瘤放射治疗医生共同阅片,根据美国肿瘤放射治疗协会(RTOG)建议的分区准则,总结淋巴结在RTOG各区的分布,并运用χ^2检验分析T分期和淋巴结转移之间的关系;进一步以舌骨和环状软骨下缘为界把颈部分成三个区组,分析淋巴结跳跃性转移的情况。结果：本组中218例(84．2％)发现有淋巴结转移,在各区的分布是Ⅰa 0例,Ⅰb 6例(2．8％),Ⅱa115例(52．8％),Ⅱb 192例(88．1％),Ⅲ78例(35．8％),Ⅳ20例(9．2％),Ⅴ65例(29．9％),Ⅵ10例,咽后157例(72．0％),耳前2例(0．9％)。各区淋巴结转移比例和T分期之间没有明显相关性～5例(2．3％)发生跳跃性转移。结论：鼻咽癌淋巴结转移率高,Ⅱa、Ⅱb区和咽后最容易发生转移。淋巴结转移基本遵循由上到下,从近到远发展的规律,很少发生跳跃性转移,T分期和各区淋巴结的转移比例之间没有明显相关性。     

Defining the target volume for post-operative radiotherapy after D2 dissection in gastric cancer by CT-based vessel-guided delineation

Purpose

To determine the recurrent nodal gross tumor volume (rnGTV) based on CT-guided vascular structure to refine the clinical target volume (CTV) delineation in postoperative radiotherapy for advanced gastric cancer following radical gastrectomy with D2 dissection.

Materials and methods

We retrospectively reviewed follow-up images from 91 patients with their first regional recurrence after D2 dissection in stage III gastric cancer with N3 disease. We defined rnGTV as recurrent nodes shown in follow-up CT images, in which one diagnostic radiologist with specialty of gastrointestinal tract investigated. We drew rnGTVs at the equivalent location based on the same vessels of reference comparing CT images to recurrence CT images.

Results

We propose vessel-based locations of rnGTVs on CT images with axial and coronal views. We show different patterns of regional recurrence according to the location of primary gastric cancer using CT and digitally reconstructed radiograph (DRR) images. Frequently recurred sites, overlapped by more than five rnGTVs, are depicted in a DRR image.

Conclusions

This study suggests vessel-based delineations of rnGTVs on CT images depending on nodal recurrence sites from follow-up images after D2 lymphadenectomy. Our results could help reduce the inter-observer variation of CTV delineation after D2 dissection in gastric cancer.     

Guidelines for delineation of lymphatic clinical target volumes for high conformal radiotherapy: head and neck region

The success of radiotherapy depends on the accurate delineation of the clinical target volume. The delineation of the lymph node regions has most impact, especially for tumors in the head and neck region. The purpose of this article was the development an atlas for the delineation of the clinical target volume for patients, who should receive radiotherapy for a tumor of the head and neck region. Literature was reviewed for localisations of the adjacent lymph node regions and their lymph drain in dependence of the tumor entity. On this basis the lymph node regions were contoured on transversal CT slices. The probability for involvement was reviewed and a recommendation for the delineation of the CTV was generated.     

Comparison of five segmentation tools for 18F-fluoro-deoxy-glucose-positron emission tomography-based target volume definition in head and neck cancer

PURPOSE: Target-volume delineation for radiation treatment to the head and neck area traditionally is based on physical examination, computed tomography (CT), and magnetic resonance imaging. Additional molecular imaging with (18)F-fluoro-deoxy-glucose (FDG)-positron emission tomography (PET) may improve definition of the gross tumor volume (GTV). In this study, five methods for tumor delineation on FDG-PET are compared with CT-based delineation. METHODS AND MATERIALS: Seventy-eight patients with Stages II-IV squamous cell carcinoma of the head and neck area underwent coregistered CT and FDG-PET. The primary tumor was delineated on CT, and five PET-based GTVs were obtained: visual interpretation, applying an isocontour of a standardized uptake value of 2.5, using a fixed threshold of 40% and 50% of the maximum signal intensity, and applying an adaptive threshold based on the signal-to-background ratio. Absolute GTV volumes were compared, and overlap analyses were performed. RESULTS: The GTV method of applying an isocontour of a standardized uptake value of 2.5 failed to provide successful delineation in 45% of cases. For the other PET delineation methods, volume and shape of the GTV were influenced heavily by the choice of segmentation tool. On average, all threshold-based PET-GTVs were smaller than on CT. Nevertheless, PET frequently detected significant tumor extension outside the GTV delineated on CT (15-34% of PET volume). CONCLUSIONS: The choice of segmentation tool for target-volume definition of head and neck cancer based on FDG-PET images is not trivial because it influences both volume and shape of the resulting GTV. With adequate delineation, PET may add significantly to CT- and physical examination-based GTV definition.     

FDG-PET/CT imaging for preradiotherapy staging of head-and-neck squamous cell carcinoma

PurposeImage localization of head-and-neck squamous cell carcinoma lags behind current techniques to deliver a precise radiation dose with intensity-modulated radiotherapy. This pilot study prospectively examined the use of registered 18-F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT for preradiotherapy staging of the neck.Methods and materialsSixty-three patients with squamous cell carcinoma of the oral cavity, oropharynx, larynx, or hypopharynx were enrolled into an institutional FDG-PET imaging protocol between September 2000 and June 2003. Of these patients, 20 went on to immediate neck dissection surgery and were studied further. Of these 20, 17 (85%) had American Joint Committee on Cancer Stage III or IV disease. All patients underwent preoperative FDG-PET and contrast-enhanced CT of the head and neck. FDG-PET/CT images were created using a nonrigid image registration algorithm developed at the University of Washington. Alternate primary and nodal gross tumor volumes were contoured with radiotherapy treatment planning software, blinded to each other and to the pathology results. One set of volumes was designed with CT guidance alone and the other with the corresponding FDG-PET/CT images. Neck dissection specimens were subdivided into surgical nodal levels intraoperatively, and the histopathologic findings were correlated with the CT and FDG-PET/CT nodal level findings.ResultsFDG-PET/CT detected 17 of 17 heminecks and 26 of 27 nodal zones histologically positive by dissection (100% and 96% sensitivity, respectively). The nodal level staging sensitivity and specificity for FDG-PET/CT was 96% (26 of 27) and 98.5% (68 of 69), respectively. FDG-PET/CT correctly detected nodal disease in 2 patients considered to have node-negative disease by CT alone. Agreement between the imaging results and pathology findings was stronger for FDG-PET/CT (κ 0.95, 95% confidence interval 0.82–0.99) than for CT alone (κ 0.81, 95% confidence interval 0.63–0.91; p = 0.06 by two-sided McNemar's testing).ConclusionThese early findings suggest that FDG-PET/CT is superior to CT alone for geographic localization of diseased neck node levels. Confirmatory trials to substantiate the accuracy of FDG-PET/CT neck staging should be prioritized.     

Lymph node‐positive head and neck cancer treated with definitive radiotherapy

BACKGROUND: The purpose was to determine if postradiotherapy (RT) neck dissection can be limited to the neck levels of residual adenopathy on post-RT computed tomography (CT). METHODS: In all, 274 patients with lymph node-positive head and neck squamous cell carcinoma were treated with definitive RT. All patients had a contrast-enhanced CT performed 4 weeks after completing RT to evaluate tumor response. Two hundred eleven heminecks were dissected, either planned pre-RT or because of residual adenopathy on post-RT CT. CT images were reviewed to determine the presence and location of residual adenopathy. Radiographic complete response (rCR) was defined as lymph node size < or =1.5 cm and normal radiographic morphology (no filling defects or calcifications). For each neck level the CT findings were correlated with neck dissection pathology. RESULTS: Correlation of CT nodal response with neck dissection pathology revealed the following negative predictive values of rCR: level I, 100%; level II, 95%; level III, 98%; level IV, 96%; and level V, 96%. A subset analysis was performed on 61 neck levels with initially positive lymph nodes that completely responded to RT that were in a hemineck with residual lymphadenopathy elsewhere in the neck. Correlation of nodal response on CT to pathology indicated a negative predictive value of an rCR of 95% for this high-risk scenario. In 71 heminecks that underwent a selective neck dissection (defined as dissection of less than levels I-V) the 5-year neck control rate was 100%. CONCLUSIONS: rCR on post-RT CT has a negative predictive value of > or =95% for each neck level. This suggests that limiting neck dissection based on post-RT CT is safe.     

Characterisation of radiotherapy planning volumes using textural analysis

Computer-based artificial intelligence methods for classification and delineation of the gross tumour volume (GTV) on computerised tomography (CT) and magnetic resonance (MR) images do not, at present, provide the accuracy required for radiotherapy applications. This paper describes an image analysis method for classification of distinct regions within the GTV, and other clinically relevant regions, on CT images acquired on eight bladder cancer patients at the radiotherapy planning stage and thereafter at regular intervals during treatment. Statistical and fractal textural features (N=27) were calculated on the bladder, rectum and a control region identified on axial, coronal and sagittal CT images. Unsupervised classification results demonstrate that with a reduced feature set (N=3) the approach offers significant classification accuracy on axial, coronal and sagittal CT image planes and has the potential to be developed further for radiotherapy applications, particularly towards an automatic outlining approach.     

Rotterdam and Brussels CT-based neck nodal delineation compared with the surgical levels as defined by the American Academy of Otolaryngology-Head and Neck Surgery

PURPOSE/OBJECTIVE: Rotterdam and Brussels have independently published guidelines for the definition and delineation of CT-based neck nodal Levels I-VI. This paper first reports on the adequacy of contouring of the Rotterdam delineation protocol. Rotterdam and Brussels differed slightly in translating the original surgical level definitions as proposed by the 2002 American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) to CT guidelines. To adapt to the surgical level definitions to come to a unifying concept, adjustments of both CT-based classifications are proposed. METHODS AND MATERIALS: The clinical neck nodal target volumes of patients irradiated in Rotterdam by three-dimensional conformal radiotherapy (3D-CRT) between December 1998 and March 2001 were reviewed. Thirty-four patients with N0 and 27 patients with N+ disease with primary tumors located in the oral cavity (n = 1) oropharynx (n = 24), hypopharynx (n = 7), and larynx (n = 29) were evaluated. Seven patients underwent unilateral (3 N0 patients, 4 N+ patients) and 54 underwent bilateral (31 N0 patients, 23 N+ patients) irradiation of the neck. In 11 N+ patients, 3D-CRT of the neck was followed by unilateral neck dissection. The dose to the primary and nonresected N+ necks was 70 Gy and to the N0 neck was 46 Gy. Neck levels were analyzed for adequacy of contouring, dose distribution, and patterns of relapse. The mean dose and the percentage of the volume receiving a minimum of 95% (V95) or >107% (V107) of the prescribed dose was computed. RESULTS: In 4 patients treated with bilateral 3D-CRT, contouring was not in concordance with the guidelines of the protocol. The V95 and V107 in the 81 adequately contoured N0 necks (63 irradiated N0 necks from 33 N0 patients, 18 irradiated N0 necks from 24 N+ patients) was 95.6% and 6.3%, respectively. For the 26 N+ necks (15 N+ necks from 13 N+ RT-only patients, 11 N+ necks from 11 preoperatively irradiated patients), the V95 and V107 was 94.6% and 6.7%, respectively. With a median follow-up of 29 months, in 4 (8.6%) of 46 patients treated by 3D-CRT only, regional relapse was found. An actuarial regional and locoregional relapse-free survival and disease-free survival rate at 3 years of 90%, 78%, and 68%, respectively, was observed. All regional relapses were observed in the N0 necks of patients with supraglottic laryngeal carcinoma. Taking the surgical 2002 AAO-HNS classification as a reference, adjustments are proposed for the Rotterdam and Brussels delineation protocols to arrive at a unified CT-based neck nodal classification. CONCLUSION: Adequate dose coverage for the Rotterdam CT-based contours of the neck nodal levels was found. In the RT-only patients, only four failures were observed: one regional and three locoregional relapses. As a next step in optimizing the current Rotterdam and Brussels CT-based delineation protocols, adaptations are proposed to resolve the discrepancies compared with the 2002 AAO-HNS surgical classification.     

Délinéation des cancers de la cavité buccale et de l’oropharynx

The aim of this article is to present the determination and the delineation of target volumes for oral cavity and oropharyngeal carcinomas treated with intensity-modulated irradiation. The delineation on the computerized tomography scanner (CT scan) requires a precise method because of the complexity of the head-and-neck anatomy. Different elements are necessary: clinical examination, diagram of the initial tumor, surgical and pathological reports and medical imaging (CT scan, magnetic resonance imaging and fluorodeoxyglucose positron emission tomography). The clinical target volumes, the planning target volumes, the organs at risk and the planning organs at risk volumes are discussed. The concept of selectivity of the potential subclinical disease near the primary tumour and the selection of neck nodal targets are specified according to the literature.     

Hybrid PET-CT simulation for radiation treatment planning in head-and-neck cancers: a brief technical report

PURPOSE: To prospectively study the impact on tumor and normal tissue delineation for RT planning by use of hybrid PET-CT simulation for patients with head-and-neck cancer. METHODS AND MATERIALS: Twenty-one patients were simulated in treatment position on a hybrid PET-CT scanner. Images were transferred to the Varian Eclipse planning system. Abnormal areas of fluorodeoxyglucose (FDG) uptake were contoured on PET for the gross tumor volume of primaries (GTVp) and abnormal nodal region of primaries (ABNp) then compared with the same CT gross tumor volumes (GTVc) and abnormal nodal region (ABNc). A statistical analysis was performed to evaluate the correlation of PET and CT volumes. RESULTS: Positron emission tomography demonstrated the primary in all cases, whereas CT did not find the primary in 3 cases. In 8 patients, additional areas of disease were seen only in PET. The average ratio of GTVc/GTVp was 3.1 (range, 0.3-23.6), whereas for ABNc/ABNp was 0.7 (range, 0-4). Volumes for the primaries were significantly larger on CT than on PET (p = 0.002) but not for nodal regions (p = 0.5). CONCLUSIONS: Hybrid PET-CT simulation is feasible and provides valuable information that results in greater delineation of normal tissues from tumor bearing areas at high risk for recurrence. This finding may further improve therapeutic window for IMRT for head-and-neck cancers.     

CT-MRI融合技术在头颈部肿瘤GTV勾画中应用的研究

目的比较CT、MRI和CT-MRI融合技术在头颈肿瘤靶区勾画中的差异,探讨CT-MRI融合技术在头颈肿瘤靶区勾画中的优势。方法 35位头颈部肿瘤患者,通过CT、MRI扫描,利用图像融合软件得到每位患者的两幅图像;同一医生对同一患者在同一时间段内依据CT、MRI和融合图像勾画出靶区,比较原发病灶的肿瘤靶区的体积(Gross tumor volume,GTV)。结果 GTV_CT、GTV_MRI、GTV_CT-MRI的平均值分别为(21.22±1.56)cm³、(23.64±1.30)cm³、(29.08±2.09)cm³,GTV_CT与GTV_MRI比较(t=7.05,P＜0.01),GTV_CT-MRI与GTV_CT比较(t=-17.82,P＜0.01);GTV_CT-MRI与GTV_MRI比较(t=13.08,P＜0.01)。结论 CT-MRI融合图像的头颈部肿瘤勾画靶区比单独MRI或CT图像的头颈部肿瘤勾画靶区更广,CT-MRI融合图像技术可提高靶区勾画的准确性,更利于指导精确放疗的实施。     

ABAS软件勾画OAR临床前测试重要性研究

目的 对基于模板自动分区(ABAS)算法的图像勾画软件进行临床前测试,评估鼻咽癌放疗计划OAR勾画精度,为确定临床应用条件提供依据。方法 以放疗医师在22例鼻咽癌患者放疗计划CT图像上手工勾画的OAR结构为评价标准,分别对ABAS软件两种算法(General和Head/Neck)自动勾画的OAR进行以下测试:(1)每1例患者均拷贝1套图像,以原图像上手工勾画的轮廓为模板在拷贝图像上自动勾画,考察自动勾画对模板的还原能力;(2)以1例患者图像上手工勾画的轮廓为模板,对其余患者图像进行自动勾画,考察采用单一模板对不同患者图像自动勾画的准确度。评价指标包括各OAR的DSC、V_diff、DSC与勾画体积相关性,以及自动勾画加手工修改与单纯手工勾画的耗时差别。Wilcoxon符号秩检验,Spearman相关性分析。结果 Head/Neck算法对模板还原能力优于或相当于General算法,自动勾画DSC与所勾画结构体积大小呈正相关(r_s=0.879、0.939)。还原测试中体积>1 cm³器官自动勾画的DSC>0.8。使用Head/Neck算法基于单一模板的自动勾画中,脑干、颞叶、腮腺、下颌骨的DSC和V_diff平均值分别为0.81~0.90和2.73%~16.02%,颞颌关节和视交叉DSC为0.45~0.49。应用自动勾画加手工修改比单纯手工勾画可以节省68%时间。结论 临床前测试可以确定ABAS算法在特定临床应用条件的准确度和适用范围,所测试软件可帮助提高鼻咽癌放疗计划OAR勾画效率,但不适用于较小体积器官的勾画。     

Retropharyngeal nodes in squamous cell carcinoma of oropharynx: incidence, localization, and implications for target volume

PURPOSE: To investigate the incidence and anatomic localization of retropharyngeal (RP) nodal involvement in patients with squamous cell carcinoma of the oropharynx. METHODS AND MATERIALS: The CT studies of 208 patients presenting with oropharyngeal carcinoma were retrospectively analyzed. The location of the nodal neck disease was registered according to recent consensus guidelines for target volume delineation, and special attention was given to the RP nodes. To obtain statistically significant predictors for RP nodal involvement, univariate and multivariate analyses were performed. RESULTS: RP adenopathies were present in 16% of all patients and in 23% of those patients with nodal disease in other neck sites. Ipsilateral involvement of Level II and contralateral involvement of Level III predicted for involvement of the ipsilateral RP nodes on multivariate analysis (p < 0.05). A solitary ipsilateral RP node was present in 3 (9%) of 34 patients with RP nodes; 2 of these 3 patients had a primary posterior pharyngeal wall tumor. No patients presented with a solitary contralateral RP node. CONCLUSION: Given the high incidence of RP nodal involvement in oropharyngeal cancer-16% of all patients and 23% of patients with pathologic nodal disease in other neck sites-RP nodes should be included in the target volume, especially in node-positive necks. In node-negative necks, inclusion of RP nodes into the target volume is advised in posterior pharyngeal wall tumors.     

An atlas of the pelvic lymph node regions to aid radiotherapy target volume definition

AimsThe implementation of advanced three-dimensional radiotherapy planning techniques requires accurate target volume localisation. We have previously developed guidelines to aid definition of the pelvic lymph node regions, and the aim of this study was to produce a CT atlas.Materials and methodsThe guidelines were applied to a CT scan of a patient to receive adjuvant radiotherapy.ResultsReference CT images of the pelvis were generated, illustrating the nodal regions and a typical target volume for adjuvant pelvic radiotherapy for gynaecological cancer.ConclusionThese images can be used as an aid for target volume definition of the pelvic nodal regions.     

428 例鼻咽癌患者颈部及Ⅴ区后缘转移淋巴结位置分布规律研究*

目的:分析鼻咽癌患者颈部及Ⅴ区后缘淋巴结的转移规律,指导鼻咽癌颈部放疗靶区的勾画。方法:回顾性分析2013年2月至2016年4 月就诊于成都军区总医院428 例经病理确诊为鼻咽癌的患者,所有患者均行颅底至锁骨下缘的增强CT模拟扫描。淋巴结分区采用RTOG 等推荐的分区指南（2013版）,由两位医师共同阅片对颈部及Ⅴ区后缘的转移淋巴结进行分析,并选取1 例N 0 期的鼻咽癌患者作为标准,参照Ⅴ区后缘正常解剖结构位置及比例,将428 例患者中有Ⅴ区后缘转移淋巴结的中心点勾画于标准病例的定位CT图像上,采用SPSS19.0 软件分析Ⅴ区后缘淋巴结转移与其余各区淋巴结之间的相关性,并分析Ⅴ区后缘转移淋巴结的位置及特点。结果:428 例患者中381 例（89.0%）出现淋巴结转移,转移概率最高的前4 位淋巴结区依次为Ⅱb（75.2%）、Ⅶa（60.3%）、Ⅱa（59.6%）、Ⅲ（42.0%）;21例（4.9%）出现Ⅴ区后缘淋巴结转移,共统计Ⅴ区后缘转移淋巴结32枚,各枚淋巴结中心点在标准患者上距斜方肌前缘的垂直距离均值为16mm。相关性分析提示Ⅴ区后缘淋巴结转移与同侧Ⅴa 区相关（P = 0.001）。 结论:鼻咽癌颈部淋巴结按照从上到下,由近及远的顺序转移,跳跃性转移的发生率低;Ⅴ区后缘淋巴结转移与同侧Va区阳性相关;Va区淋巴结转移时,同侧V 区后界的勾画应适当后移至斜方肌前缘后25mm。