Laryngeal tumor volume measurements determined with CT: a study on intra- and interobserver variability

The Role of Open Conservation Surgery in the Era of Minimally Invasive Surgery for Hypopharyngeal Cancer

Background and Objectives: Total laryngectomy with partial pharyngectomy is traditionally the principal curative treatment for hypopharyngeal cancer; however, conservative surgical approaches that minimize functional disability are attracting increasing interest. Thus, we evaluated the appropriateness and oncological outcomes of open conservation surgery for such patients. Materials and Methods: We reviewed the medical records of 49 patients who underwent vertical hemipharyngolaryngectomy from 1998 to 2018 at a single institution. Results: Locoregional recurrences developed in 19 patients (38.8%) and distant metastases in 6 (12.2%). Histopathologically, paraglottic space invasion was apparent in 13 patients (26.5%), pre-epiglottic space invasion in 4 (8.2%), thyroid cartilage invasion in 9 (18.4%), thyroid gland invasion in 2, perineural invasion in 11 (22.4%), and lymphovascular invasion in 35 (71.4%). The 5-year overall survival of patients who underwent open conservation surgery was comparable to that of patients who underwent total laryngectomy with partial pharyngectomy (68.7% vs. 48.4%, p = 0.14). Pre-epiglottic space invasion significantly decreased the 5-year disease-free survival rate after open conservation surgery (69.7% vs. 17.9%, p = 0.01). Conclusions: We found that pre-epiglottic space invasion negatively impacted disease control after open conservation surgery, emphasizing the crucial role played by a preoperative evaluation during patient selection.

Prognostic value of the maximum standardized uptake value for the locoregional control in early glottic cancer

Purpose

To evaluate the prognostic value of the pretreatment maximum standardized uptake value (SUVmax) for locoregional control (LRC) of early glottic cancer treated with primary radiotherapy.

Materials and Methods

We retrospectively reviewed the medical records of 101 patients with T1-T2N0 glottic cancer treated with helical tomotherapy between 2013 and 2016. The clinical T-stages were T1 in 87 (86.1%) and T2 in 14 (13.9%) patients. The median total dose was 63 Gy (63–67.5 Gy) in 2.25 Gy per fraction. The survival outcomes were plotted using Kaplan-Meier curves. Receiver operating characteristic curves were used to assess the optimal SUVmax cut-off value for predicting locoregional recurrence.

Results

The median follow-up period was 58 months (range, 11 to 90 months). The 5-year overall survival (OS) and locoregional recurrence-free survival rates were 96.8% and 85.4%, respectively. The median pretreatment SUVmax of the primary tumor for all 101 patients was 2.3 (range, 1.1 to 9.1). The best cut-off value for SUVmax for predicting LRC was 3.3, with a sensitivity of 78.6% and specificity of 73.6%. Univariate analysis showed that T-stage, overall treatment time (≥43 days), and high SUVmax (≥3.3) were significant predictors of LRC. Multivariate analysis showed that LRC was independently affected by a high SUVmax (≥3.3) (hazard ratio = 5.505, p = 0.020).

Conclusion

High pretreatment SUVmax (≥3.3) is a negative prognostic factor for LRC in early glottic cancer patients treated with primary radiotherapy.

Statistical harmonization can improve the development of a multicenter CT-based radiomic model predictive of nonresponse to induction chemotherapy in laryngeal cancers

PURPOSE

To develop a radiomic model predicting nonresponse to induction chemotherapy in laryngeal cancers, from multicenter pretherapeutic contrast-enhanced computed tomography (CE-CT) and evaluate the benefit of feature harmonization in such a context.

METHODS

Patients (n = 104) eligible for laryngeal preservation chemotherapy were included in five centers. Primary tumor was manually delineated on the CE-CT images. The following radiomic features were extracted with an in-house software (MIRAS v1.1, LaTIM UMR 1101): intensity, shape, and textural features derived from Gray-Level Co-occurrence Matrix (GLCM), Neighborhood Gray Tone Difference Matrix (NGTDM), Gray-Level Run Length Matrix (GLRLM), and Gray-Level Size Zone Matrix (GLSZM). Harmonization was performed using ComBat after unsupervised hierarchical clustering, used to determine labels automatically, given the high heterogeneity of imaging characteristics across and within centers. Patients with similar feature distributions were grouped with unsupervised clustering into an optimal number of clusters (2) determined with "silhouette scoring." Statistical harmonization was then carried out with ComBat on these 2 identified clusters. The cohort was split into training/validation (n = 66) and testing (n = 32) sets. Area under the receiver operating characteristics curves (AUC) were used to evaluate the ability of radiomic features (before and after harmonization) to predict nonresponse to chemotherapy, and specificity (Sp) and sensitivity (Se) were used to quantify their performance in the testing set.

RESULTS

Without harmonization, none of the features identified as predictive in the training set remained significant in the testing set. After ComBat, one textural feature identified in the training set keeps a predictive trend in the testing set-Zone Percentage, derived from the GLSZM, was predictive of nonresponse in the training set (AUC = 0.62, Se = 70%, Sp = 64%, P = 0.04) and obtained a satisfactory performance in the testing set (Se = 80%, Sp = 67%, P = 0.03), although significance was limited by the size of the testing set. These results are consistent with previously published findings in head and neck cancers.

CONCLUSIONS

Radiomic features from CE-CT could help in the selection of patients for induction chemotherapy in laryngeal cancers, with relatively good sensitivity and specificity in predicting lack of response. Statistical harmonization with ComBat and unsupervised clustering seems to improve the predictive value of features extracted in such a heterogeneous multicenter setting.

Interobserver variability in organ at risk delineation in head and neck cancer

Background

In radiotherapy inaccuracy in organ at risk (OAR) delineation can impact treatment plan optimisation and treatment plan evaluation. Brouwer et al. showed significant interobserver variability (IOV) in OAR delineation in head and neck cancer (HNC) and published international consensus guidelines (ICG) for OAR delineation in 2015. The aim of our study was to evaluate IOV in the presence of these guidelines.

Methods

HNC radiation oncologists (RO) from each Belgian radiotherapy centre were invited to complete a survey and submit contours for 5 HNC cases. Reference contours (OARref) were obtained by a clinically validated artificial intelligence-tool trained using ICG. Dice similarity coefficients (DSC), mean surface distance (MSD) and 95% Hausdorff distances (HD95) were used for comparison.

Results

Fourteen of twenty-two RO (64%) completed the survey and submitted delineations. Thirteen (93%) confirmed the use of delineation guidelines, of which six (43%) used the ICG. The OARs whose delineations agreed best with the OARref were mandible [median DSC 0.9, range (0.8–0.9); median MSD 1.1 mm, range (0.8–8.3), median HD95 3.4 mm, range (1.5–38.7)], brainstem [median DSC 0.9 (0.6–0.9); median MSD 1.5 mm (1.1–4.0), median HD95 4.0 mm (2.3–15.0)], submandibular glands [median DSC 0.8 (0.5–0.9); median MSD 1.2 mm (0.9–2.5), median HD95 3.1 mm (1.8–12.2)] and parotids [median DSC 0.9 (0.6–0.9); median MSD 1.9 mm (1.2–4.2), median HD95 5.1 mm (3.1–19.2)]. Oral cavity, cochleas, PCMs, supraglottic larynx and glottic area showed more variation. RO who used the consensus guidelines showed significantly less IOV (p = 0.008).

Conclusions

Although ICG for delineation of OARs in HNC exist, they are only implemented by about half of RO participating in this study, which partly explains the delineation variability. However, this study highlights that guidelines alone do not suffice to eliminate IOV and that more effort needs to be done to accomplish further treatment standardisation, for example with artificial intelligence.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s13014-020-01677-2.

Positron emission tomography for radiotherapy planning in head and neck cancer: What impact?

PET-computed tomography (CT) plays a growing role to guide target volume delineation for head and neck cancer in radiation oncology. Pretherapeutic [18F]FDG PET-CT adds information to morphological imaging. First, as a whole-body imaging modality, it reveals regional or distant metastases that induce major therapeutic changes in more than 10% of the cases. Moreover, it allows better pathological lymph node selection which improves overall regional control and overall survival. Second, locally, it allows us to define the metabolic tumoral volume, which is a reliable prognostic feature for survival outcome. [18F]FDG PET-CT-based gross tumor volume (GTV) is on average significantly smaller than GTV based on CT. Nevertheless, the overlap is incomplete and more evaluation of composite GTV based on PET and GTV based on CT are needed. However, in clinical practice, the study showed that using GTV PET alone for treatment planning was similar to using GTVCT for local control and dose distribution was better as a dose to organs at risk significantly decreased. In addition to FDG, pretherapeutic PET could give access to different biological tumoral volumes - thanks to different tracers - guiding heterogeneous dose delivery (dose painting concept) to resistant subvolumes. During radiotherapy treatment, follow-up [18F]FDG PET-CT revealed an earlier and more important diminution of GTV than other imaging modality. It may be a valuable support for adaptative radiotherapy as a new treatment plan with a significant impact on dose distribution became possible. Finally, additional studies are required to prospectively validate long-term outcomes and lower toxicity resulting from the use of PET-CT in treatment planning.

Radiologists and Clinical Trials: Part 1 The Truth About Reader Disagreements

The debate over human visual perception and how medical images should be interpreted have persisted since X-rays were the only imaging technique available. Concerns over rates of disagreement between expert image readers are associated with much of the clinical research and at times driven by the belief that any image endpoint variability is problematic. The deeper understanding of the reasons, value, and risk of disagreement are somewhat siloed, leading, at times, to costly and risky approaches, especially in clinical trials. Although artificial intelligence promises some relief from mistakes, its routine application for assessing tumors within cancer trials is still an aspiration. Our consortium of international experts in medical imaging for drug development research, the Pharma Imaging Network for Therapeutics and Diagnostics (PINTAD), tapped the collective knowledge of its members to ground expectations, summarize common reasons for reader discordance, identify what factors can be controlled and which actions are likely to be effective in reducing discordance. Reinforced by an exhaustive literature review, our work defines the forces that shape reader variability. This review article aims to produce a singular authoritative resource outlining reader performance's practical realities within cancer trials, whether they occur within a clinical or an independent central review.

Three-dimensional (3D) magnetic resonance volume assessment and loco-regional failure in anal cancer: early evaluation case-control study

Background

The primary aim was to test the hypothesis that deriving pre-treatment 3D magnetic resonance tumour volume (mrTV) quantification improves performance characteristics for the prediction of loco-regional failure compared with standard maximal tumour diameter (1D) assessment in patients with squamous cell carcinoma of the anus undergoing chemoradiotherapy.

Methods

We performed an early evaluation case-control study at two UK centres (2007–2014) in 39 patients with loco-regional failure (cases), and 41 patients disease-free at 3 years (controls). mrTV was determined using the summation of areas method (Vol_sum). Reproducibility was assessed using intraclass concordance correlation (ICC) and Bland-Altman limits of agreements. We derived receiver operating curves using logistic regression models and expressed accuracy as area under the curve (ROC_AUC).

Results

The median time per patient for Vol_sum quantification was 7.00 (inter-quartile range, IQR: 0.57–12.48) minutes. Intra and inter-observer reproducibilities were generally good (ICCs from 0.79 to 0.89) but with wide limits of agreement (intra-observer: − 28 to 31%; inter-observer: − 28 to 46%). Median mrTVs were greater for cases (32.6 IQR: 21.5–53.1 cm³) than controls (9.9 IQR: 5.7–18.1 cm³, p < 0.0001). The ROC_AUC for mrT-size predicting loco-regional failure was 0.74 (95% CI: 0.63–0.85) improving to 0.82 (95% CI: 0.72–0.92) when replaced with mrTV (test for ROC differences, p = 0.024).

Conclusion

Preliminary results suggest that the replacement of mrTV for mrT-size improves prediction of loco-regional failure after chemoradiotherapy for squamous cell carcinoma of the anus. However, mrTV calculation is time consuming and variation in its reproducibility are drawbacks with the current technology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07613-7.

Tumor volume as a prognostic factor of locally advanced laryngeal cancer

PURPOSE

The TNM tumor staging system is the most widely used for laryngeal cancer. However, in the same T stage, lesions with different primary tumor volumes (TV) can be found, impacting treatment outcomes.

METHODS

145 patients with T3 and T4a laryngeal cancer, according to Union for International Cancer Control, who underwent surgical treatment from 2008 to 2017, were analyzed. TV measurements were collected and compared to different outcomes.

RESULTS

The mean TV was 23.0 ± 16.4 cm³. A cutoff point for TV of 14.2 cm³ was established. Cumulative sample 5-year overall survival (OS) was 62.1%, while 5-years disease-free survival (DFS) was 65.5%. In univariate analysis, TV ≥ 14.2 cm³ was associated with a higher risk of distant metastases (p = 0.045), and worse rates of OS (p = 0.009) and DFS (p = 0.035). In multivariate analysis, TV was not an independent risk factor of worse DFS (p = 0.569) or OS (p = 0.094).

CONCLUSION

Primary lesion TV showed significant association, in univariate analysis, with worse rates of recurrence and survival in advanced laryngeal cancer undergoing surgical treatment and can be a promising prognostic for these patients.

Prognostic Factors in Early Glottic Carcinoma Implications for Treatment

Aim

In this study we aimed to determine the prognostic factors affecting local control (LC) in limited glottic carcinoma treated with definitive radiotherapy (RT).

Material and methods

Between June 1991 and December 2001, 114 patients with early squamous-cell carcinoma of the glottis were treated with definitive RT at our institution. Only four (3.5%) patients were women. The median age was 60 (27-79). Fifteen percent, 72% and 13% of the patients had Tis, T1 and T2 tumors, respectively. Forty-three (37.7%) patients had anterior commissure invasion. Prior to RT 35 (31%) patients had undergone vocal cord stripping and two (2%) cordectomy. A median dose of 66 Gy (50-70.2) was given over a median period of 46 days (20-60). Univariate and multivariate analyses were performed for LC. The prognostic parameters analyzed for LC were T classification, anterior commissure involvement, total RT dose, and overall treatment time.

Results

Five-year local and regional control rates were 84.2% and 97.7%. RTOG grade 3-4 late side effects were observed only in one (0.9%) patient. In 15 patients with local failure, salvage treatment consisted of partial laryngectomy in eight patients and total laryngectomy in five. One of the remaining two patients was medically inoperable, and the other refused salvage surgery. In one of the three patients with regional failure, salvage surgery was applied and the other two were given palliative chemotherapy because of unresectable disease. Following salvage treatments, the ultimate five-year LC rate was 96.9% and the five-year larynx preservation rate was 91.1%. Second primary cancer was diagnosed in 17 (14.9%) patients. Only one patient developed distant metastases and two patients died of laryngeal cancer. While T2 disease and anterior commissure involvement were found to be unfavorable prognostic factors significantly influencing LC in univariate analyses, only T2 disease remained independent in multivariate analysis.

Conclusion

In patients with early glottic carcinoma, T classification proved to be the only independent prognostic factor affecting LC after primary radiotherapy according to the results of this study.

Computed tomography volumetry of esophageal cancer - the role of semiautomatic assessment

Background

The clinical and research value of Computed Tomography (CT) volumetry of esophageal cancer tumor size remains controversial. Development in CT technique and image analysis has made CT volumetry less cumbersome and it has gained renewed attention. The aim of this study was to assess esophageal tumor volume by semi-automatic measurements as compared to manual.

Methods

A total of 23 esophageal cancer patients (median age 65, range 51–71), undergoing CT in the portal-venous phase for tumor staging, were retrospectively included between 2007 and 2012. One radiology resident and one consultant radiologist measured the tumor volume by semiautomatic segmentation and manual segmentation. Reproducibility of the respective measurements was assessed by intraclass correlation coefficients (ICC) and by average deviation from mean.

Results

Mean tumor volume was 46 ml (range 5-137 ml) using manual segmentation and 42 ml (range 3-111 ml) using semiautomatic segmentation. Semiautomatic measurement provided better inter-observer agreement than traditional manual segmentation. The ICC was significantly higher for semiautomatic segmentation in comparison to manual segmentation (0.86, 0.56, p < 0.01). The average absolute percentage difference from mean was reduced from 24 to 14% (p < 0.001) when using semiautomatic segmentation.

Conclusions

Semiautomatic analysis outperforms manual analysis for assessment of esophageal tumor volume, improving reproducibility.

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

OBJECTIVES

Volumetric tumor growth velocity (TGV) reflects in vitro tumor aggressiveness, but its prognostic value has not been investigated in vivo. We examined the prognostic impact of TGV on oncologic outcomes in patients with oropharyngeal squamous cell cancer (OSCC).

MATERIALS AND METHODS

101 OSCC patients with two pretreatment CTs with time gap of 2 or more weeks treated at a single institution between 2004 and 2008 were identified. Primary tumor and nodal targets were segmented in scans. Linear growth rates were calculated. Recursive partitioning analysis (RPA) identified cut point associated with outcomes.

RESULTS

Median follow-up was 59months (range 7-118). Median primary TGV was 0.65% increase per day (range 0-9.37%). RPA identified TGV cut point associated with local control (LC) of 1% per day. Patients with higher TGV had decreased 5-year LC (73% vs. 98%, p=0.0004), distant control (DC, 62% vs. 91%, p=0.0007), and overall survival (OS, 38% versus 93%, p<0.0001). In multivariate analysis including demographics, tumor stage, subsite, and treatment factors, TGV⩾1% per day independently predicted worsened LC (p = 0.02), DC (p = 0.003), and OS (p < 0.0001). However, this TGV cutoff was not significantly predictive of LC, DC, or OS for a subset of presumed HPV-positive patients.

CONCLUSION

OSCC TGV⩾1% per day is a substantive negative prognostic indicator for disease control and overall survival, particularly in HPV non-associated tumors. This novel CT-based volumetric assessment of TGV suggests a simple methodology for risk stratification of patients.

Reliability of Interpretation of CT Examination of the Larynx in Patients with Glottic Laryngeal Carcinoma

INTRODUCTION: Reports in literature suggest that tumor volume, cartilage invasion, and cartilage sclerosis are independent prognostic factors for tumor control in radiotherapy as primary treatment of laryngeal carcinomas.

OBJECTIVE: Assessment of the interobserver variability and prognostic value in the measurement of tumor volume, cartilage invasion, and sclerosis.

MATERIALS AND METHODS: Retrospective analysis of 55 CT scans by three independent observers. Volume measurements and determination of cartilage invasion, cartilage sclerosis, and tumor localization were calculated. Correlation between the prognostic factors and radiotherapy was calculated for each observer.

RESULTS: Values for interobserver agreement varied substantially; cartilage invasion (κ value: −0.02 to 0.66), cartilage sclerosis (κ value: 0.13 to 0.57), tumor localization of subsites (κ value: 0.03 to 0.60), and tumor volume (correlation: 0.34 to 0.73). The found interobserver variation makes it impossible to establish accurate prognostic factors.

CONCLUSION: Determination of tumor volume, cartilage invasion, and cartilage sclerosis on the basis of CT imaging shows considerable interobserver variation; clinical significance appears to be limited.

EBM rating: B-3a

Deformable image registration and interobserver variation in contour propagation for radiation therapy planning

Deformable image registration (DIR) and interobserver variation inevitably introduce uncertainty into the treatment planning process. The purpose of the current work was to measure deformable image registration (DIR) errors and interobserver variability for regions of interest (ROIs) in the head and neck and pelvic regions. Measured uncertainties were combined to examine planning margin adequacy for contours propagated for adaptive therapy and to assess the trade‐off of DIR and interobserver uncertainty in atlas‐based automatic segmentation. Two experienced dosimetrists retrospectively contoured brainstem, spinal cord, anterior oral cavity, larynx, right and left parotids, optic nerves, and eyes on the planning CT (CT1) and attenuation‐correction CT of diagnostic PET/CT (CT2) for 30 patients who received radiation therapy for head and neck cancer. Two senior radiation oncology residents retrospectively contoured prostate, bladder, and rectum on the postseed‐implant CT (CT1) and planning CT (CT2) for 20 patients who received radiation therapy for prostate cancer. Interobserver variation was measured by calculating mean Hausdorff distances between the two observers' contours. CT2 was deformably registered to CT1 via commercially available multipass B‐spline DIR. CT2 contours were propagated and compared with CT1 contours via mean Hausdorff distances. These values were summed in quadrature with interobserver variation for margin analysis and compared with interobserver variation for statistical significance using two‐tailed t‐tests for independent samples (α=0.05). Combined uncertainty ranged from 1.5‐5.8 mm for head and neck structures and 3.1‐3.7 mm for pelvic structures. Conventional 5 mm margins may not be adequate to cover this additional uncertainty. DIR uncertainty was significantly less than interobserver variation for four head and neck and one pelvic ROI. DIR uncertainty was not significantly different than interobserver variation for four head and neck and one pelvic ROI. DIR uncertainty was significantly greater than interobserver variation for two head and neck and one pelvic ROI. The introduction of DIR errors may offset any reduction in interobserver variation by using atlas‐based automatic segmentation.

PACS number(s): 87.57.nj, 87.55.D‐

Tumor Volumes and Prognosis in Laryngeal Cancer

Tumor staging systems for laryngeal cancer (LC) have been developed to assist in estimating prognosis after treatment and comparing treatment results across institutions. While the laryngeal TNM system has been shown to have prognostic information, varying cure rates in the literature have suggested concern about the accuracy and effectiveness of the T-classification in particular. To test the hypothesis that tumor volumes are more useful than T classification, we conducted a retrospective review of 78 patients with laryngeal cancer treated with radiation therapy at our institution. Using multivariable analysis, we demonstrate the significant prognostic value of anatomic volumes in patients with previously untreated laryngeal cancer. In this cohort, primary tumor volume (GTV_P), composite nodal volumes (GTV_N) and composite total volume (GTV_P + GTV_N = GTV_C) had prognostic value in both univariate and multivariate cox model analysis. Interestingly, when anatomic volumes were measured from CT scans after a single cycle of induction chemotherapy, all significant prognosticating value for measured anatomic volumes was lost. Given the literature findings and the results of this study, the authors advocate the use of tumor anatomic volumes calculated from pretreatment scans to supplement the TNM staging system in subjects with untreated laryngeal cancer. The study found that tumor volume assessment after induction chemotherapy is not of prognostic significance.

Spatio-temporal stability of pre-treatment 18F-Fludeoxyglucose uptake in head and neck squamous cell carcinomas sufficient for dose painting

BACKGROUND

The pre-treatment 18F-Fludeoxyglucose (FDG) avid subvolume of the tumor has shown promise as a potential target for dose painting in patients with in head and neck squamous cell carcinomas (HNSCC).

PURPOSE

The purposes of this study are: 1) to assess the pre-treatment spatio-temporal variability of FDG PET/CT target volumes and 2) to assess the impact of this variability on dose distribution in dose painting plans in patients with HNSCC.

MATERIAL AND METHODS

Thirty patients were enrolled and scanned twice, three days apart, days prior to treatment. Delineation of the FDG avid subvolume of the tumor and lymph nodes on both scans was performed by a specialist in nuclear medicine yielding GTVPET1 and GTVPET2 and segmentation based on SUV iso-contours were constructed yielding two metabolic target volumes, MTV1 and MTV2. Images were co-registered rigidly and dose painting plans with dose escalation up to 82 Gy to GTVPET1 were planned and GTVPET2 was copied from the co-registered images to the dose planning scan. Variation in dose to the target and modeled tumor control probability were assessed as measures of the impact of imaging variations in a dose painting scenario.

RESULTS

Twenty-four patients were available for full analysis. The median mismatch between GTVPET1 and GTVPET2 was 14.2% (1.7 cm(3)). The median difference in dose to the FDG planning target volume was 0.3 Gy (PTVPET) and 0.4 Gy (PTVMTV). Median difference in the modeled tumor control probability (TCP) was < 0.2% and 23 of 24 patients had a difference in expected TCP < 1%.

CONCLUSIONS

Pre-treatment FDG PET/CT target volumes were stable and day-to-day variability had no relevant impact on dose distribution and expected tumor control in dose painting plans.

The value of magnetic resonance imaging for radiotherapy planning

The success of highly conformal radiotherapy techniques in the sparing of normal tissues or in dose escalation, or both, relies heavily on excellent imaging. Because of its superior soft tissue contrast, magnetic resonance imaging is increasingly being used in radiotherapy treatment planning. This review discusses the current clinical evidence to support the pivotal role of magnetic resonance imaging in radiation oncology.

PET imaging biomarkers in head and neck cancer

In locally advanced head and neck squamous cell carcinoma (HNSCC), the role of imaging becomes more and more critical in the management process. In this framework, molecular imaging techniques such as PET allow noninvasive assessment of a range of tumour biomarkers such as metabolism, hypoxia and proliferation, which can serve different purposes. First, in a pretreatment setting they can influence therapy selection strategies and target delineation for radiation therapy. Second, their predictive and/or prognostic value could help enhance the therapeutic ratio in the management of HNSCC. Third, treatment modification can be performed through the generation of a molecular-based heterogeneous dose distribution with dose escalation to the most resistant parts of the tumour, a concept known as dose painting. Fourth, they are increasingly becoming a tool for monitoring response to therapy. In this review, PET imaging biomarkers used in the routine management of HNSCC or under investigation are discussed.

MRI to delineate the gross tumor volume of nasopharyngeal cancers: which sequences and planes should be used?

Background

Magnetic resonance imaging (MRI) has been found to be better than computed tomography for defining the extent of primary gross tumor volume (GTV) in advanced nasopharyngeal cancer. It is routinely applied for target delineation in planning radiotherapy. However, the specific MRI sequences/planes that should be used are unknown.

Methods

Twelve patients with nasopharyngeal cancer underwent primary GTV evaluation with gadolinium-enhanced axial T1 weighted image (T1) and T2 weighted image (T2), coronal T1, and sagittal T1 sequences. Each sequence was registered with the planning computed tomography scans. Planning target volumes (PTVs) were derived by uniform expansions of the GTVs. The volumes encompassed by the various sequences/planes, and the volumes common to all sequences/planes, were compared quantitatively and anatomically to the volume delineated by the commonly used axial T1-based dataset.

Results

Addition of the axial T2 sequence increased the axial T1-based GTV by 12% on average (p = 0.004), and composite evaluations that included the coronal T1 and sagittal T1 planes increased the axial T1-based GTVs by 30% on average (p = 0.003). The axial T1-based PTVs were increased by 20% by the additional sequences (p = 0.04). Each sequence/plane added unique volume extensions. The GTVs common to all the T1 planes accounted for 38% of the total volumes of all the T1 planes. Anatomically, addition of the coronal and sagittal-based GTVs extended the axial T1-based GTV caudally and cranially, notably to the base of the skull.

Conclusions

Adding MRI planes and sequences to the traditional axial T1 sequence yields significant quantitative and anatomically important extensions of the GTVs and PTVs. For accurate target delineation in nasopharyngeal cancer, we recommend that GTVs be outlined in all MRI sequences/planes and registered with the planning computed tomography scans.

The role of tumor volume in radiotherapy of patients with head and neck cancer

The assumption that the larger tumor contains a higher number of clonogenic cells what may deteriorate prognosis of patients treated with RT has been confirmed in many clinical studies. Significant prognostic influence of tumor volume (TV) on radiotherapy (RT) outcome has been found for tumors of different localizations including patients with head and neck cancer (HNC). Although TV usually is a stronger prognostic factor than T stage, commonly used TNM classification system dose not incorporate TV data. The aim of the paper is to refresh clinical data regarding the role of TV in RT of patients with HNC. At present somehow new meaning of TV could be employed in the aspect of modern RT techniques and combined treatment strategies. For larger TV more aggressive treatment options may be considered. In modern RT techniques escalated dose could be provided highly conformal or RT can be combined with systemic treatment increasing therapeutic ratio. In the study several reports estimating prognostic value of TV for patients with HNC treated with RT has been reviewed.Due to substantially various reported groups of patients as to tumor site, stage of disease or treatment strategies, precise cut-off value could not be establish in general, but the significant association between TV and treatment outcome had been found in almost all studies. There is a strong suggestion that TV should supplement clinical decision in the choice of optimal treatment strategy for patients with HNC.

Semiautomatic methods for segmentation of the proliferative tumour volume on sequential FLT PET/CT images in head and neck carcinomas and their relation to clinical outcome

PURPOSE

Radiotherapy of head and neck cancer induces changes in tumour cell proliferation during treatment, which can be depicted by the PET tracer (18)F-fluorothymidine (FLT). In this study, three advanced semiautomatic PET segmentation methods for delineation of the proliferative tumour volume (PV) before and during (chemo)radiotherapy were compared and related to clinical outcome.

METHODS

The study group comprised 46 patients with 48 squamous cell carcinomas of the head and neck, treated with accelerated (chemo)radiotherapy, who underwent FLT PET/CT prior to treatment and in the 2nd and 4th week of therapy. Primary gross tumour volumes were visually delineated on CT images (GTV CT). PVs were visually determined on all PET scans (PV VIS). The following semiautomatic segmentation methods were applied to sequential PET scans: background-subtracted relative-threshold level (PV RTL), a gradient-based method using the watershed transform algorithm and hierarchical clustering analysis (PV W&C), and a fuzzy locally adaptive Bayesian algorithm (PV FLAB).

RESULTS

Pretreatment PV VIS correlated best with PV FLAB and GTV CT. Correlations with PV RTL and PV W&C were weaker although statistically significant. During treatment, the PV VIS, PV W&C and PV FLAB significant decreased over time with the steepest decline over time for PV FLAB. Among these advanced segmentation methods, PV FLAB was the most robust in segmenting volumes in the third scan (67 % of tumours as compared to 40 % for PV W&C and 27 % for PV RTL). A decrease in PV FLAB above the median between the pretreatment scan and the scan obtained in the 4th week was associated with better disease-free survival (4 years 90 % versus 53 %).

CONCLUSION

In patients with head and neck cancer, FLAB proved to be the best performing method for segmentation of the PV on repeat FLT PET/CT scans during (chemo)radiotherapy. This may potentially facilitate radiation dose adaptation to changing PV.

Impact of primary tumor volume on local control after definitive radiotherapy for head and neck cancer

BACKGROUND

The impact of primary tumor volume (pTV) on local control after definitive radiotherapy (RT) for head and neck squamous cell carcinoma (HNSCC) is unclear.

METHODS

Pertinent literature was reviewed to address the impact of pTV on local control after definitive RT for HNSCC.

RESULTS

Reproducibility of pTV calculations is probably influenced by interobserver variability and may be reduced by relying on experienced observers. The impact of pTV on local control after definitive RT is probably influenced by primary site. A relatively limited impact of pTV on local control after RT for oropharyngeal squamous cell carcinomas (SCCs) might be attributable to human papillomavirus (HPV) positivity.

CONCLUSION

pTV may be a useful parameter to select patients for treatment with definitive RT, particularly for those with laryngeal SCCs. Patients with high-volume primary cancers, in which the probability of local control with a functional larynx is low, are likely better treated with surgery.

Tumor volume of resectable adenocarcinoma of the esophagogastric junction at multidetector CT: association with regional lymph node metastasis and N stage

PURPOSE

To determine whether the volume of resectable adenocarcinoma of the esophagogastric junction (AEG) measured at multidetector computed tomography (CT) is associated with regional lymph node metastasis and N stage.

MATERIALS AND METHODS

The study was approved by the institutional ethics committee, and written informed consent was obtained from each participant. Two hundred sixteen patients with resectable AEG prospectively underwent contrast material-enhanced thoracoabdominal multidetector CT less than 2 weeks before curative resection. Gross tumor volume was retrospectively measured on CT scans. Univariate and multivariate analyses were performed to identify whether gross tumor volume is associated with regional lymph node metastasis. The Mann-Whitney U test was performed to compare gross tumor volume among N stages, with Bonferroni correction for multigroup comparisons. Receiver operating characteristic analysis was performed to determine if gross tumor volume could help classify N stage.

RESULTS

Univariate analysis showed that gross tumor volume is associated with regional lymph node metastasis (P < .0001). Multivariate analysis revealed that gross tumor volume is an independent risk factor of lymph node metastasis (P = .023, odds ratio = 2.791). The Mann-Whitney U test showed that gross tumor volume could help differentiate between stage N0 and stages N1-N2 or N1-N3 disease and between stages N1-N2 and stage N3 disease (P < .0001 for all). In patients with stage T1-T3 AEG, gross tumor volume could help differentiate between stage N0 and stages N1-N2 (cutoff, 15.23 cm(3)) or N1-N3 (cutoff, 17.16 cm(3)) disease and between stages N1-N2 and stage N3 disease (cutoff, 33.96 cm(3)). In patients with stage T3 AEG, gross tumor volume could help differentiate stage N0 from stages N1-N2 (cutoff, 18.41 cm(3)) or N1-N3 (cutoff, 19.30 cm(3)) disease and stages N1-N2 from stage N3 disease (cutoff, 33.96 cm(3)).

CONCLUSION

Gross tumor volume of AEG measured with multidetector CT is associated with regional lymph node metastasis and N stage.

A quantitative comparison of gross tumour volumes delineated on [18F]-FDG PET-CT scan and CECT scan in head and neck cancers

Purpose:

To compare quantitatively Gross tumor volume (GTV), both primary and nodal areas of head and neck cancers, delineated on [18F]-2fluoro, 2deoxy d-glucose-positron emission tomography/computed tomography ([18F]-FDG-PET-CT) scan to those delineated on Contrast-enhanced CT scan (CECT scan).

Methods:

A total of 26 consecutive patients with squamous cell cancers of head and neck were included in this study. The primary sites were oropharynx (n = 7), hypopharynx (n = 6), paranasal sinus (n = 6), nasopharynx (n = 4), oral cavity (n = 2), and one with unknown primary and secondary neck node. All patients underwent routine staging work-up. FDG-PET and CECT scans were performed with dedicated PET-CT scanner in single session as a part of the radiotherapy treatment planning for Intensity modulated radiotherapy/Image-guided radiotherapy.

Results:

All patients had abnormal increased uptake in PET-CT scans. PET-CT resulted in changes of CT-based staging in 8 of 26 patients (up-staged in 7 and down-staged in 1). The mean primary and nodal GTV volumes on PET-CT and CT were significantly different (primary: PET-GTV: 48.43 ± 53.21 cc vs. CT 54.78 ± 64.47 cc, P < 0.001; nodes: PET-GTV: 12.72 ± 15.46 cc vs. 11.04 ± 14.87 cc, P < 0.001). The mismatch between two target volumes was statistically significant (P = 0.03 for GTV primary, P = 0.04 for GTV node).

Conclusion:

Accuracy of delineation of GTV can be improved along with functional imaging using [18F]-FDG. These metabolically active volumes are significantly smaller than CT-based volumes and could be missed during conventional CT-based target delineations of GTVs.

Interobserver variation in parotid gland delineation: a study of its impact on intensity-modulated radiotherapy solutions with a systematic review of the literature

OBJECTIVES

This study evaluates the interobserver variation in parotid gland delineation and its impact on intensity-modulated radiotherapy (IMRT) solutions.

METHODS

The CT volumetric data sets of 10 patients with oropharyngeal squamous cell carcinoma who had been treated with parotid-sparing IMRT were used. Four radiation oncologists and three radiologists delineated the parotid gland that had been spared using IMRT. The dose-volume histogram (DVH) for each study contour was calculated using the IMRT plan actually delivered for that patient. This was compared with the original DVH obtained when the plan was used clinically.

RESULTS

70 study contours were analysed. The mean parotid dose achieved during the actual treatment was within 10% of 24 Gy for all cases. Using the study contours, the mean parotid dose obtained was within 10% of 24 Gy for only 53% of volumes by radiation oncologists and 55% of volumes by radiologists. The parotid DVHs of 46% of the study contours were sufficiently different from those used clinically, such that a different IMRT plan would have been produced.

CONCLUSION

Interobserver variation in parotid gland delineation is significant. Further studies are required to determine ways of improving the interobserver consistency in parotid gland definition.

Interobserver variation in clinical target volume and organs at risk segmentation in post-parotidectomy radiotherapy: can segmentation protocols help?

OBJECTIVE

A study of interobserver variation in the segmentation of the post-operative clinical target volume (CTV) and organs at risk (OARs) for parotid tumours was undertaken. The segmentation exercise was performed as a baseline, and repeated after 3 months using a segmentation protocol to assess whether CTV conformity improved.

METHODS

Four head and neck oncologists independently segmented CTVs and OARs (contralateral parotid, spinal cord and brain stem) on CT data sets of five patients post parotidectomy. For each CTV or OAR delineation, total volume was calculated. The conformity level (CL) between different clinicians' outlines was measured using a validated outline analysis tool. The data for CTVs were re-analysed after using the cochlear sparing therapy and conventional radiation segmentation protocol.

RESULTS

Significant differences in CTV morphology were observed at baseline, yielding a mean CL of 30% (range 25-39%). The CL improved after using the segmentation protocol with a mean CL of 54% (range 50-65%). For OARs, the mean CL was 60% (range 53-68%) for the contralateral parotid gland, 23% (range 13-27%) for the brain stem and 25% (range 22-31%) for the spinal cord.

CONCLUSIONS

There was low conformity for CTVs and OARs between different clinicians. The CL for CTVs improved with use of a segmentation protocol, but the CLs remained lower than expected. This study supports the need for clear guidelines for segmentation of target and OARs to compare and interpret the results of head and neck cancer radiation studies.

Evaluation of a metal artifact reduction technique in tonsillar cancer delineation

PURPOSE

Metal artifacts can degrade computed tomographic (CT) simulation imaging and impair accurate delineation of tumors for radiation treatment planning purposes. We investigated a Digital Imaging and Communications in Medicine-based metal artifact reduction technique in tonsillar cancer delineation.

METHODS AND MATERIALS

Eight patients with significant artifact and tonsil cancer were evaluated. Each patient had a positron emission tomography (PET)-CT and a contrast-enhanced CT obtained at the same setting during radiotherapy simulation. The CTs were corrected for artifact using the metal deletion technique (MDT). Two radiation oncologists independently delineated primary gross tumor volumes (GTVs) for each patient on native (CTnonMDT), metal corrected (CTMDT), and reference standard (CTPET/nonMDT) imaging, 1 week apart. Mixed effects models were used to determine if differences among GTVs were statistically significant. Two diagnostic radiologists and 2 radiation oncologists independently qualitatively evaluated CTs for each patient. Ratings were on an ordinal scale from -3 to +3, denoting that CTMDT was markedly, moderately, or slightly worse or better than CTnonMDT. Scores were compared with a Wilcoxon signed-rank test.

RESULTS

The GTVPET/nonMDT were significantly smaller than GTVnonMDT (P = .004) and trended to be smaller than GTVMDT (P = .084). The GTVnonMDT and GTVMDT were not significantly different (P = .93). There was no significant difference in the extent to which GTVnonMDT or GTVMDT encompassed GTVPET/nonMDT (P = .33). In the subjective assessment of image quality, CTMDT did not significantly outperform CTnonMDT. In the majority of cases, the observer rated the CTMDT equivalent to (53%) or slightly superior (41%) to the corresponding CTnonMDT.

CONCLUSIONS

The MTD modified images did not produce GTVMDT that more closely reproduced GTVPET/nonMDT than did GTVnonMDT. Moreover, the MTD modified images were not judged to be significantly superior when compared to the uncorrected images in terms of subjective ability to visualize the tonsilar tumors. This study failed to demonstrate value of the adjunctive use of a CT corrected for artifacts in the tumor delineation process. Artifacts do make tumor delineation challenging, and further investigation of other body sites is warranted.

[Utility of PET-CT on radiotherapy planning of head and neck cancer. Our initial experience]

OBJECTIVE

To describe the methods used for the incorporation of FDG-PET-CT on radiotherapy planning of patients with head and neck cancer and also to evaluate the impact of FDG-PET-CT on staging and tumor volume definition.

MATERIAL AND METHODS

A prospective study in which 20 patients with head and neck tumor submitted for radiotherapy treatment were included. All underwent a whole body PET- CT (GE DSTE 16) for staging and restaging, also acquiring an additional 3h delayed PET image with diagnostic CT parameters for planning. A CT scan with diagnostic protocol, tabletop available for radiotherapy treatment and the same personalized head-shoulder mask were used in the latter. Lymph node involvement and/or distant involvement were evaluated, considering the changes in staging. We also evaluated the differences in volumes obtained between the different techniques. The threshold value used for delineating PET gross tumor volume (GTV) was empirically established and ranged from 20-40% of the maximum SUV.

RESULTS

Radiotherapy planning was performed with PET-CT in 20 patients between October 2007 to September 2008. A total of 29 lesions (18 primary lesions because 2 patients were excluded as no tumor was observed on the PET CT images, and 11 nodes). The most frequent location was oropharynx (5 patients). Mean maxSUV of the 29 lesions was 14.4 (range 5.0 and 26.4). No statistically significant differences were found between the GTV PET and GTV CT (mean 21.9cm³ and 19.3cm³, respectively). PET-CT modified the staging in 20% of the patients, with a diagnostic and therapeutic impact of 50 and 25%, respectively.

CONCLUSION

The incorporation of PET-CT in routine radiotherapy planning is a promising technique that requires close collaboration between the nuclear medicine and radiotherapy oncology departments. PET-CT achieves better staging in patients and has a significant diagnostic and therapeutic impact. The use of the hybrid technique avoids problems arising from co-registry as well as a second examination for planning with the consequent advantage for the patient. Nonetheless, more prospective and randomized studies with pathology specimens are needed to evaluate the real impact in the tumor volume definition.

CT perfusion in solid-body tumours. Part I: Technical issues

Functional imaging is becoming increasingly important in both research and clinical diagnostic radiology. Perfusion computed tomography (CTP) is a readily available and widely used tool that allows an objective measurement of tissue perfusion through the mathematical analysis of data obtained from repeated scans performed after administration of contrast agent. Recently, CTP has been increasingly used in the oncological field, being studied as a potential marker of neoplastic angiogenesis, which is one of the main targets of new tumour therapies. The aim of this paper was to provide the theoretical background and practical guidance for accurately performing CTP and interpreting results of examinations in solid-body tumours. CTP could be a valid tool for functional imaging of tumours if the acquisition technique is robust, if image and data analysis is accurate and if interpretation of results is adequately inserted within a clinical context.

The Impact of Hybrid PET-CT Scan on Overall Oncologic Management, with a Focus on Radiotherapy Planning: A Prospective, Blinded Study

Functional imaging using fluorodeoxyglucose positron-emission tomography (FDG-PET) has been increasing incorporated into radiotherapy planning in conjunction with computed tomography (CT). Hybrid FDG-PET/CT scanners allow these images to be obtained in very close temporal proximity without the need for repositioning patients, thereby minimizing imprecision when overlying these images. To prospectively examine the impact of hybrid PET/CT imaging on overall oncologic impact, with a focus on radiotherapy planning, we performed a prospective, blinded trial in 111 patients. Patients with lung cancer (n=38), head-and-neck squamous cell carcinoma (n=23), breast (n=8), cervix (n=15), esophageal (n=9), and lymphoma (n=18) underwent hybrid PET/CT imaging at the time of radiation therapy planning. A physician blinded to the PET dataset designed a treatment plan using all clinical information and the CT dataset. The treating physician subsequently designed a second treatment plan using the hybrid PET/CT dataset. The two treatment plans were compared to determine if a major alteration in overall oncologic management occured. In patients receiving potentially curative radiotherapy the concordance between CT-based and PET/CT-based GTVs was quantified using an index of conformality (CI). In 76/111 (68%) of patients, the PET/CT data resulted in a change in one or more of the following: GTV volume, regional/local extension, prescribed dose, or treatment modality selection. In 35 of these 76 cases (46%; 31.5% of the entire cohort) the change resulted in a major alteration in the oncologic management (dose, field design, or modality change). Thus, nearly a third of all cases had a major alteration in oncologic management as a result of the PET/CT data, and 29 of 105 patients (27.6%) who underwent potentially curative radiotherapy had major alterations in either dose or field design. Hybrid PET/CT imaging at the time of treatment planning may be highly informative and an economical manner in which to obtain PET imaging, with the dual goals of staging and treatment planning.

The importance of pre-epiglottis space invasion in the treatment planning of larynx and hypopharynx cancer

The involvement of pre-epiglottis space can change the indication for partial laryngeal resection.

Aim

The aim of this study was to evaluate inter-observer and intra-observer agreement by means of computed tomography analysis regarding the involvement of the pre-epiglottis space (PES) from carcinoma of the upper aerodigestive tract and its relation with therapeutic planning.

Materials and Methods

Retrospective study of ninety-five computed tomography exams of patients with squamous cell carcinoma, from 1990 to 2004, were selected and evaluated; 87 were males and eight females, with ages ranging from 32 to 73 years. Imaging results were analyzed twice by three radiologists, individually, without any previous knowledge of the clinical stage. No patient had received any previous treatment up to the moment of imaging examination, such as surgery, chemotherapy or radiotherapy. All the cases were confirmed by biopsy. Information was obtained from the medical charts.

Results

Kappa Index was calculated by assessing agreement between the three observers. We obtained substantial to almost perfect levels of agreement.

Conclusions

After a general Kappa Index of 0.72, the results suggest a substantial agreement in the involvement of the PES by means of computed tomography analysis.

Tumor-volume changes after radiosurgery for vestibular schwannoma: implications for follow-up MR imaging protocol

BACKGROUND AND PURPOSE

The outcome of radiosurgery for vestibular schwannoma (VS) is assessed by posttreatment measurement of tumor size and could be influenced by the timing and quality of the assessment. This study evaluates the volumetric changes of VS after radiosurgery and proposes a radiologic follow-up program.

MATERIALS AND METHODS

Of 142 patients with VS treated with radiosurgery, we selected patients who were followed at least 3 times during a minimum of 32 months with a T1-weighted gadolinium-enhanced high-resolution 3D MR imaging examination identical to the pretreatment MR imaging. Forty-five patients were identified with a mean follow-up of 50 months (range, 32-78 months). Pre- and posttreatment tumor volumes were calculated by using BrainSCAN software by manually contouring tumors on each MR imaging study. Volume changes of >13% were defined as events.

RESULTS

At last follow-up MR imaging, volumes were smaller in 37 (82.2%) of the 45 patients. Eleven (29.7%) of these 37 tumors showed transient swelling preceding regression, with a median time to regression of 34 months (range, 20-55 months). Seven (15.6%) of the 45 tumors had volume progression compared with the tumor on pretreatment MR imaging studies. Of these 7 tumors, 3, however, had volume regression compared with the preceding MR imaging study, and in 4, volume progression was ongoing. One tumor remained the same.

CONCLUSIONS

Tumor-volume measurements by standardized T1-weighted gadolinium-enhanced high-resolution 3D MR imaging follow-up protocols revealed good local control of VS after radiosurgery. The first-follow-up MR imaging at 2 years and the second at 5 years postradiosurgery differentiated transient progression from ongoing progression and may prevent unnecessary therapeutic interventions.

Current concepts on imaging in radiotherapy

New high-precision radiotherapy (RT) techniques, such as intensity-modulated radiation therapy (IMRT) or hadrontherapy, allow better dose distribution within the target and spare a larger portion of normal tissue than conventional RT. These techniques require accurate tumour volume delineation and intrinsic characterization, as well as verification of target localisation and monitoring of organ motion and response assessment during treatment. These tasks are strongly dependent on imaging technologies. Among these, computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US) and positron emission tomography (PET) have been applied in high-precision RT. For tumour volume delineation and characterization, PET has brought an additional dimension to the management of cancer patients by allowing the incorporation of crucial functional and molecular images in RT treatment planning, i.e. direct evaluation of tumour metabolism, cell proliferation, apoptosis, hypoxia and angiogenesis. The combination of PET and CT in a single imaging system (PET/CT) to obtain a fused anatomical and functional dataset is now emerging as a promising tool in radiotherapy departments for delineation of tumour volumes and optimization of treatment plans. Another exciting new area is image-guided radiotherapy (IGRT), which focuses on the potential benefit of advanced imaging and image registration to improve precision, daily target localization and monitoring during treatment, thus reducing morbidity and potentially allowing the safe delivery of higher doses. The variety of IGRT systems is rapidly expanding, including cone beam CT and US. This article examines the increasing role of imaging techniques in the entire process of high-precision radiotherapy.

[18FDG] PET-CT-based intensity-modulated radiotherapy treatment planning of head and neck cancer

PURPOSE

To define the best threshold for tumor volume delineation of the (18) fluoro-2-deoxy-glucose positron emission tomography ((18)FDG-PET) signal for radiotherapy treatment planning of intensity-modulated radiotherapy (IMRT) in head and neck cancer.

METHODS AND MATERIALS

In 25 patients with head-and-neck cancer, CT-based gross tumor volume (GTV(CT)) was delineated. After PET-CT image fusion, window level (L) was adapted to best fit the GTV(CT), and GTV(PET) was delineated. Tumor maximum (S) and background uptake (B) were measured, and the threshold of the background-subtracted tumor maximum uptake (THR) was used for PET signal segmentation. Gross tumor volumes were expanded to planning target volumes (PTVs) and analyzed.

RESULTS

The mean value of S was 40 kBq/mL, S/B ratio was 16, and THR was 26%. The THR correlated with S (r = -0.752), but no correlation between THR and the S/B ratio was seen (r = -0.382). In 77% of cases, S was >30 kBq/mL, and in 23% it was </=30 kBq/mL, with a mean THR of 21.4% and 41.6%, respectively (p < 0.001). Using PTV(PET) in radiotherapy treatment planning resulted in a reduced PTV in 72% of cases, while covering 88.2% of GTV(CT), comparable to the percentage of GTV(PET) covered by PTV(CT) (p = 0.15).

CONCLUSIONS

A case-specific PET signal threshold is optimal in PET-based radiotherapy treatment planning. Signal gating using a THR of 20% in tumors with S >30% +/- 1.6% kBq/mL and 40% in tumors with S </=30% +/- 1.6% kBq/mL is suitable.

Defining the target for radiotherapy of head and neck cancer

The greatest challenge for radiation therapy is to attain the highest probability of cure with the least morbidity. Implementation of conformal radiotherapy techniques offers the possibility to target irregularly shaped volumes while optimally sparing the normal tissues. This implies however an accurate knowledge of the exact tumour extension. In order to perfectly delineate the primary tumour and to optimise the radiation dose administered to normal tissues, it is necessary for patients to undergo imaging studies. Both anatomical and functional imaging studies are currently being evaluated for treatment planning of head and neck cancer.

O valor da tomografia computadorizada na mudança do paradigma cirúrgico do carcinoma epidermóide de boca e orofaringe

OBJETIVO: Determinar a importância da tomografia computadorizada na mudança do paradigma cirúrgico no carcinoma espinocelular (CEC) da boca e orofaringe. MÉTODO: De 1991 e 2004, nos Departamentos de Cirurgia de Cabeça e Pescoço/ORL e Radiologia do Hospital Heliópolis, foram analisados, retrospectivamente, tomografias computadorizadas de 30 pacientes, 25 homens e cinco mulheres, com idades variando de 25 a 77 anos, todos com diagnóstico de carcinoma epidermóide do soalho da boca e/ou da língua oral e orofaringe. Todos os exames foram avaliados por dois radiologistas, separadamente, sem o conhecimento prévio do estadiamento clínico, sendo analisada a disseminação local-regional para os diferentes sítios. Para análise interobservadores, o índice Kappa foi calculado para estimar a concordância entre os mesmos, sendo o nível de significância adotado o valor de 0,05. RESULTADO: A análise da concordância entre os observadores foi considerada excelente (Kappa: 0,81 - 1,00) para três subsítios (linha média, espaço mastigador e cadeia linfonodal jugulo-carotídea alta); boa (Kappa: 0,61 - 0,80) para 10 subsítios (soalho da boca e língua oral, ramo da mandíbula, trígono retromolar, espaço submandibular, loja amigdalina e cadeias linfonodais submentoniana, submandibular, jugulo-carotídea média, jugulo-carotídea baixa e espinal); moderada (Kappa: 0,41 - 0,60) para dois subsítios (corpo da mandíbula e base da língua) e não foi possível calcular o Kappa para um subsítio (cadeia linfonodal retrofaríngea). CONCLUSÃO: A concordância interobservadores predominou de boa a excelente, sendo os valores estatisticamente significantes.

Tumour volume measurement in head and neck cancer

Tumour volume is a significant prognostic factor in the treatment of malignant head and neck tumours. Studies of laryngeal and pharyngeal tumours have shown tumour volume to be an important predictor for tumour recurrence. Some studies (for instance nasopharyngeal carcinoma) have shown through multivariate modelling that tumour volume is a dominant covariate that overwhelms T stage, N stage and stage group. The results of these studies have prompted several investigators to suggest the inclusion of tumour volume as an additional prognostic factor in future revisions of the TNM staging system. This paper briefly reviews the TNM system as a staging tool, the measurement of tumour volume and how tumour volume could possibly be incorporated in the system or used as an additional prognostic factor.

Automatic delineation of on-line head-and-neck computed tomography images: toward on-line adaptive radiotherapy

PURPOSE

To develop and validate a fully automatic region-of-interest (ROI) delineation method for on-line adaptive radiotherapy.

METHODS AND MATERIALS

On-line adaptive radiotherapy requires a robust and automatic image segmentation method to delineate ROIs in on-line volumetric images. We have implemented an atlas-based image segmentation method to automatically delineate ROIs of head-and-neck helical computed tomography images. A total of 32 daily computed tomography images from 7 head-and-neck patients were delineated using this automatic image segmentation method. Manually drawn contours on the daily images were used as references in the evaluation of automatically delineated ROIs. Two methods were used in quantitative validation: (1) the dice similarity coefficient index, which indicates the overlapping ratio between the manually and automatically delineated ROIs; and (2) the distance transformation, which yields the distances between the manually and automatically delineated ROI surfaces.

RESULTS

Automatic segmentation showed agreement with manual contouring. For most ROIs, the dice similarity coefficient indexes were approximately 0.8. Similarly, the distance transformation evaluation results showed that the distances between the manually and automatically delineated ROI surfaces were mostly within 3 mm. The distances between two surfaces had a mean of 1 mm and standard deviation of <2 mm in most ROIs.

CONCLUSION

With atlas-based image segmentation, it is feasible to automatically delineate ROIs on the head-and-neck helical computed tomography images in on-line adaptive treatments.

Measurement by multidetector CT scan of the volume of hypopharyngeal and laryngeal tumours: accuracy and reproducibility

The purpose of this study was to register the accuracy and reproducibility of the multidetector computed tomography (MDCT) estimate of hypopharyngeal and laryngeal tumor volumes. Eighteen consecutive patients with larynx or hypopharynx squamous cell carcinoma were enrolled in this prospective trial, scheduled for surgery and examined by MDCT. A total of 72 tumor volume measurements were reported by two different operators, one of them in three different sessions, using the sum-of-areas method. The results were compared with the volume calculated by surgical sampling. The mean tumor volume measured by MDCT was 5.7 +/- 9.3 ml (range 0.1-41.6). The mean volume measured from the surgical specimens was 5.6 +/- 8.6 ml (range 0.06-33.6). The level of agreement between histological and MDCT volumes was high, with a slight tendency of MDCT to overestimation, proportional to the size. The analysis of interoperator variability showed a tendency of the more expert operator to make more accurate estimates, but the differences were not significant (P = 0.62, 0.75 and 0.63). The evaluation of the three different sessions of the less expert operator revealed a good repeatability. According to our study, MDCT estimate of tumor volume is an effective, reproducible method. MDCT tends to produce more dispersed results in case of large tumors.

From anatomical to biological target volumes: the role of PET in radiation treatment planning

Progress in radiation oncology requires a re-evaluation of the methods of target volume delineation beyond anatomical localization. New molecular imaging techniques for tumour visualisation such as positron emission tomography (PET) provide insight into tumour characteristics and can be complementary to the anatomical data of computed tomography or magnetic resonance imaging. In this review, three issues are discussed: First, can PET identify a tumour more accurately? Second, can biological tumour characteristics be visualised? Third, can intratumoural heterogeneity of these characteristics be identified?

Advanced imaging applied to radiotherapy planning in head and neck cancer: a clinical review

Head and neck squamous cell carcinoma represents an ideal model to investigate the application of recent advances in medical imaging to radiotherapy planning. Tumours usually remain localized, and are potentially curable with local radiation. The steep radiation dose-response relationships support the strategies of radiation dose escalation to increase local control. Two-dimensional simulator-based planning and CT planning have significant drawbacks in terms of accurate target volume definition. MRI has enhanced soft tissue delineation, but has to be fused with CT to allow dose calculation. Functional imaging using dynamic contrast enhanced CT or MRI sequences may allow improved knowledge of tumour function. Positron emission tomography (PET) may allow further physiological information to be determined. This review summarizes the current techniques in clinical development in this area.

Variability of gross tumor volume delineation in head-and-neck cancer using CT and PET/CT fusion

PURPOSE

To assess the need for gross tumor volume (GTV) delineation protocols in head-and-neck cancer (HNC) treatment planning by use of positron emission tomography (PET)/computed tomography (CT) fusion imaging. Assessment will consist of interobserver and intermodality variation analysis.

METHODS AND MATERIALS

Sixteen HNC patients were accrued for the study. Four physicians (2 neuroradiologists and 2 radiation oncologists) contoured GTV on 16 patients. Physicians were asked to contour GTV on the basis of the CT alone, and then on PET/CT fusion. Statistical analysis included analysis of variance for interobserver variability and Student's paired sample t test for intermodality and interdisciplinary variability. A Boolean pairwise analysis was included to measure degree of overlap.

RESULTS

Near-significant variation occurred across physicians' CT volumes (p = 0.09) and significant variation occurred across physicians' PET/CT volumes (p = 0.0002). The Boolean comparison correlates with statistical findings. One radiation oncologist's PET/CT fusion volumes were significantly larger than his CT volumes (p < 0.01). Conversely, the other radiation oncologist's CT volumes tended to be larger than his fusion volumes (p = 0.06). No significant interdisciplinary variation was seen. Significant disagreement occurred between radiation oncologists.

CONCLUSION

Significant differences in GTV delineation were found between multiple observers contouring on PET/CT fusion. The need for delineation protocol has been confirmed.

Inter-observer variability in the delineation of pharyngo-laryngeal tumor, parotid glands and cervical spinal cord: comparison between CT-scan and MRI

BACKGROUND AND PURPOSE

The goal of this study was to compare the inter-observer variability between CT and MRI for the delineation of pharyngo-laryngeal SCC, parotid glands and spinal cord.

PATIENTS AND METHODS

Twenty pharyngo-laryngeal tumors were delineated by five observers on CT and MRI, using consistent delineation guidelines. Spinal cords and parotid glands were also delineated on CT and MRI by three observers. Mean GTVs and coefficients of variation were calculated for each observer and compared using ANOVA and its derived Pearson intra-class coefficient (R). For GTVs, a mismatch analysis (ratio between intersection and union volumes) was also performed.

RESULTS

Regarding oropharyngeal GTVs (n=10), no significant difference was observed between observers either with CT (33.9, 31.1, 32, 34 and 34.7 ml, five observers, P=0.47) or with MRI (30.5, 29.4, 30.1 and 31.5 ml, four observers, P=0.59). CVs (13.6 vs 12.9%), (0.98 vs 0.99) and mismatches (0.43 vs 0.42) between CT and MRI did not significantly differ. Regarding laryngeal-hypopharyngeal GTVs (n=10), no significant difference was observed between observers either on CT (18.1, 20.7, 20.9, 19.3 and 21.9 ml, five observers, P=0.29) or on MRI (19.3, 21.5, 20, 22.1 and 21.8 ml, five observers, P=0.16). CVs (20.2 vs 13.8%), (0.94 vs 0.94) and mismatches (0.31 vs 0.41) were comparable. Regarding OARs, a small but significant difference in mean parotid volume was observed between observers (P<0.001) and between modalities (P<0.001) (CT: 34.8, 29.4, and 26.8 ml; MRI: 30.6, 27.9 and 20.4 ml). Similar results were obtained for mean spinal cord volumes (CT: 10.7, 10.6, and 9.5 ml; MRI: 8.7, 8.5 and 8.2 ml; P=0.05).

18F-fluoro-2-deoxy-D-glucose positron emission tomographic imaging: recent developments in head and neck cancer

PURPOSE OF REVIEW

Positron emission tomography using 18F-fluoro-2-deoxy-D-glucose (18FDG-PET) is well established in clinical routine as a metabolism-based whole-body imaging tool for cancer diagnosis and follow-up. Several reports have appeared indicating the potential and limitations of this technique in head and neck cancer (HNC). This review limits its scope to the recent advances using 18FDG-PET in the clinical management of HNC.

RECENT FINDINGS

The combination of 18FDG-PET and sentinel node biopsy has been explored for the surgical treatment planning of oral and oropharyngeal cancer. Recent reports indicate that multimodality imaging combining PET with high-end CT scanning increases the diagnostic accuracy. 18FDG-PET has a potential for use in radiation treatment planning and for the prediction of response and early evaluation of treatment efficacy.

SUMMARY

Increasingly 18FDG-PET is used as a clinical imaging modality in the different stages of the management of HNC. In particular, its clinical value in initial staging of neck lymph nodes and in the evaluation of recurrent or residual disease is well established. In these settings 18FDG-PET has been shown to be more accurate than conventional imaging. Recent studies indicate that 18FDG-PET could be of additional value in staging the N0 neck, in radiation treatment planning, and in prediction of treatment efficacy.

Prognostic significance of EGF receptor expression in early glottic cancer

OBJECTIVE

A positive relationship between epidermal growth factor receptor (EGFR) expression and radioresistance has been shown both in vitro and in vivo. In a group of 31 patients with early glottic cancer treated with definitive radiotherapy, the relationship of EGFR expression with patient and tumor related parameters were analyzed and the prognostic effect of EGFR expression on local control (LC) was assessed.

MATERIAL AND METHOD

Between 1991 and 2001, 114 patients with early glottic (Tis-T2N0M0) squamous cell carcinoma were treated with radiotherapy at our institution. Among these, 31 patients whose pretreatment pathology specimens were available for immunohistochemical analysis formed the study population. Median age was 64 (46-77). Anterior commissure involvement was evident in 12 (38.7%) patients. Distribution according to T stage was as follows: Tis 6 (19.3%), T1 22 (71%), and T2 3 (9.7%). Histopathological grades of the 25 T1-2 tumors were 10/25 (40%) grade 1, 9/25 (36%) grade 2 and 6/25 (24%) grade 3. Our radiotherapy regimen was 66-70 Gy in 33-35 fractions over 6.5-7 weeks. The median follow-up period was 45 months (range, 5-116). Following immunohistochemical staining, quantitative immunohistochemistry (IHC) was performed by image analysis software and stained tumoral area percentage (STAP) was identified. The cut-off value was < or =5% versus >5%. The relationship of EGFR expression with patient (age) and tumor related (T stage, histopathological grade, and anterior commissure involvement) parameters was evaluated using chi-square test. Prognostic significance of EGFR expression, age, T stage, histopathological grade, and anterior commissure involvement on LC was assessed using log-rank test.

RESULTS

No difference was found in EGFR content distribution in relation to age, T stage, histopathological grade, and anterior commissure involvement. In the univariate analysis including age (< or =60 versus >60), T stage (Tis and T1 versus T2), histopathological grade (grade 1 and 2 versus grade 3), anterior commissure involvement (present versus absent), and EGFR expression (high versus low), only T stage and EGFR expression were found to be significant prognostic factors affecting LC (P = 0.0006 and P = 0.03, respectively).

CONCLUSION

The results of this series support that EGFR expression is an unfavorable prognostic factor in early glottic carcinomas. For this reason EGFR IHC may be considered for selecting patients for more aggressive therapies (radiotherapy with different fractionation schemes or surgery) or enrollment into trials targeting EGFR signaling pathways.