Does consensus contour improve robustness and accuracy in 18F-FDG PET radiomic features?

PURPOSE

The purpose of our study is to validate the robustness and accuracy of consensus contour in 2-deoxy-2-[18 F]fluoro-D-glucose (18 F-FDG) PET radiomic features.

METHODS

225 nasopharyngeal carcinoma (NPC) and 13 extended cardio-torso (XCAT) simulated data were enrolled. All segmentation were performed with four segmentation methods under two different initial masks, respectively. Consensus contour (ConSeg) was then developed using the majority vote rule. 107 radiomic features were extracted by Pyradiomics based on segmentation and the intraclass correlation coefficient (ICC) was calculated for each feature between masks or among segmentation, respectively. In XCAT ICC between segmentation and simulated ground truth were also calculated to access the accuracy.

RESULTS

ICC varied with the dataset, segmentation method, initial mask and feature type. ConSeg presented higher ICC for radiomic features in robustness tests and similar ICC in accuracy tests, compared with the average of four segmentation results. Higher ICC were also generally observed in irregular initial masks compared with rectangular masks in both robustness and accuracy tests. Furthermore, 19 features (17.76%) had ICC ≥ 0.75 in both robustness and accuracy tests for any of the segmentation methods or initial masks. The dataset was observed to have a large impact on the correlation relationships between radiomic features, but not the segmentation method or initial mask.

CONCLUSIONS

The consensus contour combined with irregular initial mask could improve the robustness and accuracy in radiomic analysis to some extent. The correlation relationships between radiomic features and feature clusters largely depended on the dataset, but not segmentation method or initial mask.

Quarter Century Positron Emission Tomography/Computed Tomography Transformation of Oncology: Head and Neck Cancer

During the last 2 decades, f-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F FDG PET/CT) has transformed the clinical head and neck cancer imaging for patient management and predicting survival outcomes. It is now widely used for staging, radiotherapy planning, posttherapy assessment, and for detecting recurrence in head and neck cancers and is widely included in NCCN and other evidence based clinical practice guidelines. Future Directions would include evaluating the potential value of FAPI PET/CT for head and neck cancers, opportunity to use volumetric and tumor heterogeneity parameters and deploying AI in diagnostic and therapeutic assessments.

ACR Appropriateness Criteria® Staging and Post-Therapy Assessment of Head and Neck Cancer

Imaging of head and neck cancer at initial staging and as part of post-treatment surveillance is a key component of patient care as it guides treatment strategy and aids determination of prognosis. Head and neck cancer includes a heterogenous group of malignancies encompassing several anatomic sites and histologies, with squamous cell carcinoma the most common. Together this comprises the seventh most common cancer worldwide. At initial staging comprehensive imaging delineating the anatomic extent of the primary site, while also assessing the nodal involvement of the neck is necessary. The treatment of head and neck cancer often includes a combination of surgery, radiation, and chemotherapy. Post-treatment imaging is tailored for the evaluation of treatment response and early detection of local, locoregional, and distant recurrent tumor. Cross-sectional imaging with CT or MRI is recommended for the detailed anatomic delineation of the primary site. PET/CT provides complementary metabolic information and can map systemic involvement. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Multimodality radiomics analysis based on [18F]FDG PET/CT imaging and multisequence MRI: application to nasopharyngeal carcinoma prognosis

OBJECTIVES

To determine whether radiomics models developed from 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) PET/CT combined with multisequence MRI could contribute to predicting the progression-free survival (PFS) of nasopharyngeal carcinoma (NPC) patients.

METHODS

One hundred thirty-two NPC patients who underwent both PET/CT and MRI scanning were retrospectively enrolled (88 vs. 44 for training vs. testing). For each modality/sequence (i.e., PET, CT, T1, T1C, and T2), 1906 radiomics features were extracted from the primary tumor volume. Univariate Cox model and correlation analysis were used for feature selection. A multivariate Cox model was used to establish radiomics signature. Prognostic performances of 5 individual modality models and 12 multimodality models (3 integrations × 4 fusion strategies) were assessed by the concordance index (C-index) and log-rank test. A clinical-radiomics nomogram was built to explore the clinical utilities of radiomics signature, which was evaluated by discrimination, calibration curve, and decision curve analysis (DCA).

RESULTS

The radiomics signatures of individual modalities showed limited prognostic efficacy with a C-index of 0.539-0.664 in the testing cohort. Different fusion strategies exhibited a slight difference in predictive performance. The PET/CT and MRI integrated model achieved the best performance with a C-index of 0.745 (95% CI, 0.619-0.865) in the testing cohort (log-rank test, p < 0.05). Clinical-radiomics nomogram further improved the prognosis, which also showed satisfactory discrimination, calibration, and net benefit.

CONCLUSIONS

Multimodality radiomics analysis by combining PET/CT with multisequence MRI could potentially improve the efficacy of PFS prediction for NPC patients.

KEY POINTS

• Individual modality radiomics models showed limited performance in prognosis evaluation for NPC patients. • Combined PET, CT and multisequence MRI radiomics signature could improve the prognostic efficacy. • Multilevel fusion strategies exhibit comparable performance but feature-level fusion deserves more attention.

Does consensus contours improve robustness and accuracy on [Formula: see text]F-FDG PET imaging tumor delineation?

PURPOSE

The aim of this study is to explore the robustness and accuracy of consensus contours with 225 nasopharyngeal carcinoma (NPC) clinical cases and 13 extended cardio-torso simulated lung tumors (XCAT) based on 2-deoxy-2-[[Formula: see text]F]fluoro-D-glucose ([Formula: see text]F-FDG) PET imaging.

METHODS

Primary tumor segmentation was performed with two different initial masks on 225 NPC [Formula: see text]F-FDG PET datasets and 13 XCAT simulations using methods of automatic segmentation with active contour, affinity propagation (AP), contrast-oriented thresholding (ST), and 41% maximum tumor value (41MAX), respectively. Consensus contours (ConSeg) were subsequently generated based on the majority vote rule. The metabolically active tumor volume (MATV), relative volume error (RE), Dice similarity coefficient (DSC) and their respective test-retest (TRT) metrics between different masks were adopted to analyze the results quantitatively. The nonparametric Friedman and post hoc Wilcoxon tests with Bonferroni adjustment for multiple comparisons were performed with [Formula: see text] 0.05 considered to be significant.

RESULTS

AP presented the highest variability for MATV in different masks, and ConSeg presented much better TRT performances in MATV compared with AP, and slightly poorer TRT in MATV compared with ST or 41MAXin most cases. Similar trends were also found in RE and DSC with the simulated data. The average of four segmentation results (AveSeg) showed better or comparable results in accuracy for most cases with respect to ConSeg. AP, AveSeg and ConSeg presented better RE and DSC in irregular masks as compared with rectangle masks. Additionally, all methods underestimated the tumour boundaries in relation to the ground truth for XCAT including respiratory motion.

CONCLUSIONS

The consensus method could be a robust approach to alleviate segmentation variabilities, but did not seem to improve the accuracy of segmentation results on average. Irregular initial masks might be at least in some cases attributable to mitigate the segmentation variability as well.

Pre-CCRT 18-fluorodeoxyglucose PET-CT improves survival in patients with advanced stages p16-negative oropharyngeal squamous cell carcinoma via accurate radiation treatment planning

PURPOSE

No large-scale prospective randomized study with a long-term follow-up period has evaluated the survival outcomes of preconcurrent chemoradiotherapy (CCRT) 18-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸FDG PET-CT) in patients with non-human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC).

PATIENTS AND METHODS

We included patients with stage I-IVA p16-negative OPSCC receiving definitive CCRT and categorized them into two groups according to pre-CCRT ¹⁸FDG PET-CT and compared their outcomes: the case group consisted of patients who underwent pre-CCRT ¹⁸FDG PET-CT, whereas the comparison group consisted of patients who did not receive pre-CCRT ¹⁸FDG PET-CT.

RESULTS

The final cohort consisted of 3942 patients (1663 and 2279 in the case and comparison groups, respectively). According to multivariable Cox regression analysis, pre-CCRT ¹⁸FDG PET-CT was not a significant prognostic factor for overall survival in patients with stages I-II of p16-negative OPSCC receiving standard CCRT. The adjusted hazard ratio (95% confidence interval) of all-cause death for the patients with advanced stages (III-IVA) of p16-negative OPSCC receiving pre-CCRT ¹⁸FDG PET-CT was 0.75 (0.87-0.94, P = 0.0236).

CONCLUSIONS

Routine use of pre-CCRT ¹⁸FDG PET-CT is not necessary for each patient with p16-negative OPSCC. Pre-CCRT ¹⁸FDG PET-CT is associated with improved survival in patients with stage III-IVA p16-negative OSCC, but might be not in those with stage I-II p16-negative OPSCC. No large-scale prospective randomized study with a long-term follow-up period has evaluated the survival outcomes of preconcurrent chemoradiotherapy (CCRT) 18-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸FDG PET-CT) in patients with p16-negative oropharyngeal squamous cell carcinoma (OPSCC). Our study is the first, largest, homogenous modality study on PET-CT including a long-term follow-up cohort to examine the survival outcomes of pre-CCRT ¹⁸FDG PET-CT or non-pre-CCRT PET-CT for patients with p16-negative OPSCC receiving standard CCRT stratified by different clinical stages. Routine use of pre-CCRT ¹⁸FDG PET-CT is not necessary for each patient with p16-negative OPSCC. Pre-CCRT ¹⁸FDG PET-CT is associated with improved survival in patients with stage III-IVA p16-negative OPSCC, but might be not in those with stage I-II p16-negative OPSCC.

Survival effect of pretreatment FDG-PET-CT on nasopharyngeal cancer

BACKGROUND/PURPOSE

Accurate staging is the first step for optimal treatment selection in patients with nasopharyngeal carcinoma (NPC). In this propensity-score-matched, population-based cohort study, we investigated the survival effects of pretreatment 8-fluorodeoxyglucose positron emission tomography-computed tomography (¹⁸FDG-PET-CT) on patients with NPC.

METHODS

We included patients with stage I-IVA NPC receiving radiotherapy or concurrent chemoradiotherapy and categorized them into two 1:1 propensity score-matched groups according to whether or not they underwent pretreatment ¹⁸FDG-PET-CT and compared their outcomes.

RESULTS

Of the 10,756 patients, propensity score matching yielded 4366 patients in each group. According to multivariable Cox regression analyses, the most prominent correlation between pretreatment ¹⁸FDG-PET-CT and all-cause death was observed in patients with stage II NPC (adjusted hazard ratio [aHR], 0.77; 95% confidence interval [CI], 0.60-0.90; P = .0433), followed by patients with stage III NPC (aHR, 0.81; 95% CI, 0.69-0.94; P = .0071) and patients with stage IVA NPC (aHR, 0.88; 95% CI, 0.79-0.97; P = .0091). This association was not significant in patients with stage I NPC (aHR, 1.20; 95% CI, 0.75-1.93; P = .4426).

CONCLUSION

Pretreatment ¹⁸FDG-PET-CT is associated with longer survival in patients with clinical stage II-IVA NPC but not in stage I NPC.

Pretreatment [18F]FDG PET/CT and MRI in the prognosis of nasopharyngeal carcinoma

OBJECTIVE

The present study aimed to assess the prognostic interest of metabolic and anatomic parameters derived from 2-deoxy-2-[¹⁸F]fluoro-D-glucose positron emission tomography/computed tomography ([¹⁸F]FDG PET/CT) and head and neck magnetic resonance imaging (HN-MRI) for better management of nasopharyngeal carcinoma (NPC).

METHODS

In this study, pre-treatment [¹⁸F]FDG PET/CT and HN-MRI parameters of NPC patients diagnosed between January 2017 and December 2018, were prospectively investigated. Correlation between those parameters and 4-year patient's survival outcomes was evaluated using Kaplan-Meier and Cox-regression analyses.

RESULTS

Our results revealed a significant association between pre-treatment nodal-maximum standardized uptake value (N-SUV max) and N categories (p = 0.01), between pre-treatment node-to-tumor SUV ratio (NTR) and both tumor size (p = 0.01) and N categories (p = 0.009), as well as between metabolic tumor volume (MTV) and both tumor size and NPC overall stage (p < 0.000). In multivariate analyses, pre-treatment N-SUV max, NTR and MTV were significant independent predictors of overall survival, distant metastasis-free survival, and progression-free survival (PFS) (p < 0.05). N-SUV max and MTV were also found to be significant independent predictors of loco-regional recurrence-free survival (p < 0.05), whereas HN-MRI detection of skull-base bone invasion was an independent factor associated with worse PFS in NPC (p = 0.03).

CONCLUSIONS

The present study highlights N-SUV max, NTR and MTV derived from [¹⁸F]FDG PET/CT, and skull-base bone invasion defined by HN-MRI, as promising metabolic and anatomic prognosis biomarkers for NPC.

PET-CT in Clinical Adult Oncology-V. Head and Neck and Neuro Oncology

Simple Summary

Positron emission tomography (PET), typically combined with computed tomography (CT) has become a critical advanced imaging technique in oncology. With PET-CT, a radioactive molecule (radiotracer) is injected in the bloodstream and localizes to sites of tumor because of specific cellular features of the tumor that accumulate the targeting radiotracer. The CT scan, performed at the same time, provides information to facilitate attenuation correction, so that radioactivity from deep or dense structures can be better visualized, but with head and neck malignancies it is critical to provide correlating detailed anatomic imaging. PET-CT has a variety of applications in oncology, including staging, therapeutic response assessment, restaging, and surveillance. This series of six review articles provides an overview of the value, applications, and imaging and interpretive strategies of PET-CT in the more common adult malignancies. The fifth report in this series provides a review of PET-CT imaging in head and neck and neuro oncology.

Abstract

PET-CT is an advanced imaging modality with many oncologic applications, including staging, assessment of response to therapy, restaging, and longitudinal surveillance for recurrence. The goal of this series of six review articles is to provide practical information to providers and imaging professionals regarding the best use of PET-CT for specific oncologic indications, and the potential pitfalls and nuances that characterize these applications. In addition, key tumor-specific clinical information and representative PET-CT images are provided to outline the role that PET-CT plays in the management of oncology patients. Hundreds of different types of tumors exist, both pediatric and adult. A discussion of the role of FDG PET for all of these is beyond the scope of this review. Rather, this series of articles focuses on the most common adult malignancies that may be encountered in clinical practice. It also focuses on FDA-approved and clinically available radiopharmaceuticals, rather than research tracers or those requiring a local cyclotron. The fifth review article in this series focuses on PET-CT imaging in head and neck tumors, as well as brain tumors. Common normal variants, key anatomic features, and benign mimics of these tumors are reviewed. The goal of this review article is to provide the imaging professional with guidance in the interpretation of PET-CT for the more common head and neck malignancies and neuro oncology, and to inform the referring providers so that they can have realistic expectations of the value and limitations of PET-CT for the specific type of tumor being addressed.

Deep Learning-Guided Fiberoptic Raman Spectroscopy Enables Real-Time In Vivo Diagnosis and Assessment of Nasopharyngeal Carcinoma and Post-treatment Efficacy during Endoscopy

In this work, we develop a deep learning-guided fiberoptic Raman diagnostic platform to assess its ability of real-time in vivo nasopharyngeal carcinoma (NPC) diagnosis and post-treatment follow-up of NPC patients. The robust Raman diagnostic platform is established using innovative multi-layer Raman-specified convolutional neural networks (RS-CNN) together with simultaneous fingerprint and high-wavenumber spectra acquired within sub-seconds using a fiberoptic Raman endoscopy system. We have acquired a total of 15,354 FP/HW in vivo Raman spectra (control: 1761; NPC: 4147; and post-treatment (PT): 9446) from 888 tissue sites of 418 subjects (healthy control: 85; NPC: 82; and PT: 251) during endoscopic examination. The optimized RS-CNN model provides an overall diagnostic accuracy of 82.09% (sensitivity of 92.18% and specificity of 73.99%) for identifying NPC from control and post-treatment patients, which is superior to the best diagnosis performance (accuracy of 73.57%; sensitivity of 89.74%; and specificity of 58.10%) using partial-least-squares linear-discriminate-analysis, proving the robustness and high spectral information sensitiveness of the RS-CNN model developed. We further investigate the saliency map of the best RS-CNN models using the correctly predicted Raman spectra. The specific Raman signatures that are related to the cancer-associated biomolecular variations (e.g., collagens, lipids, and nucleic acids) are uncovered in the map, validating the diagnostic capability of RS-CNN models to correlate with biomolecular signatures. Deep learning-based Raman spectroscopy is a powerful diagnostic tool for rapid screening and surveillance of NPC patients and can also be deployed for longitudinal follow-up monitoring of post-treatment NPC patients to detect early cancer recurrences in the head and neck.

High Pretreatment Platelet-to-Albumin Ratio Predicts Poor Survival Results in Locally Advanced Nasopharyngeal Cancers Treated with Chemoradiotherapy

Purpose

In a lack of similar research, we assessed the prognostic utility of pretreatment platelet-to-albumin ratio (PAR) in locally advanced nasopharyngeal carcinoma (LANPC) patients managed with concurrent chemoradiotherapy (CCRT).

Patients and Methods

Present retrospective analysis included a sum of 128 consecutively treated LANPC patients who underwent cisplatinum-based radical CCRT. Availability of an ideal pretreatment PAR cutoff that may stratify the study population into two cohorts with significantly distinct survival outcomes was sought by utilizing the receiver operating characteristic (ROC) curve analysis. The primary and secondary endpoints were overall survival (OS) and progression-free survival (PFS), respectively.

Results

A rounded 5.2 [area under the curve (AUC): 68.9%; sensitivity: 67.4%; and specificity: 65.2%] value was identified as the ideal PAR cutoff that grouped patients into two gatherings [PAR≥5.2 (N=60) versus <5.2 (N=68)]. The median follow-up duration was 86.4 months (range: 9-147). Kaplan-Meier comparisons between the two PAR groups revealed significantly diminished median PFS (69.4 versus 106.8 months for PAR<5.2; P< 0.012) and OS (88.3 versus not reached yet for PAR<5.2; P= 0.023) for the PAR ≥ 5.2 group. The results of multivariate analyses affirmed the pretreatment PAR≥5.2 as an independent prognostic factor that indicates diminished PFS (P= 0.016) and OS (P= 0.019) together with the respective N_2-3 nodal stage (versus N_0-1; P<0.05 for PFS and OS, respectively) and weight loss >5% at past six months (≤5%; P<0.05 for PFS and OS, respectively).

Conclusion

The results of the current retrospective analysis provided a robust and independent adverse prognostic value for pretreatment PAR ≥ 5.2 in terms of median and long-term PFS and OS outcomes in LA-NPC patients this patient group treated with conclusive CCRT.

Nasopharyngeal carcinoma in children and adolescents: The EXPeRT/PARTNER diagnostic and therapeutic recommendations

Nasopharyngeal carcinoma (NPC) is a rare pediatric tumor. Collaborative studies performed over the last decades showed improved results compared to historical data, but standardized guidelines for diagnosis and management of pediatric NPC are still unavailable. This study presents a European consensus guideline for the diagnosis and treatment of pediatric NPC developed by the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT). Main recommendations include induction chemotherapy with cisplatin and 5-flurouracil, concomitant chemoradiotherapy in advanced disease, and to consider maintenance treatment with interferon beta (IFN-β) for selected high-risk patients. Dose adjustments of radiotherapy based on response to induction chemotherapy may decrease the rates of long-term treatment-related complications that affect most of the survivors.

Pretreatment 18F-FDG uptake heterogeneity can predict treatment outcome of carbon ion radiotherapy in patients with locally recurrent nasopharyngeal carcinoma

OBJECTIVE

Our study was to investigate the value of pretreatment ¹⁸F-FDG uptake heterogeneity to predict the prognosis of patients with locally recurrent nasopharyngeal carcinoma (LRNPC) treated by carbon ion radiotherapy (CIRT).

METHODS

Twenty-nine LRNPC patients who underwent whole-body ¹⁸F-FDG PET/CT scanning before CIRT were enrolled. Heterogeneity index (HI)-based ¹⁸F-FDG uptake, and the PET/CT traditional parameters, including SUVmax, MTV, and TLG were assessed. Receiver operator characteristics (ROC) determined the best cutoff value, and local recurrence-free survival (LRFS) and progression-free survival (PFS) were evaluated by the Kaplan-Meier method and log-rank test. And the predictive ability was evaluated by the ROC curve. Cox analyses were performed on LRFS and PFS.

RESULTS

In this study, univariate analysis showed that HI was a significant predictor of LRNPC treated by CIRT. HI could be used to predict LRFS and PFS. Patients with HI (≥ 0.81) had a significantly worse prognosis of LRFS (12.25 vs. NR, p = 0.008), and of PFS (10.58 vs. NR, p = 0.014). The AUC and its sensitivity and sensitivity and specificity were 0.75, 84.21% and 70.00% for LRFS and 0.82, 80.95% and 75.00% for PFS, respectively. Multivariate analysis showed that HI was an independent predictor for the LFRS of LRNPC with CIRT.

CONCLUSION

¹⁸F-FDG uptake heterogeneity may be useful for predicting the prognosis of patients with LRNPC treated by CIRT.

Observer agreement and accuracy of 18F-sodium fluoride PET/computed tomography in the diagnosis of skull-base bone invasion and osseous metastases in newly diagnosed nasopharyngeal carcinoma

OBJECTIVES

To evaluate the interobserver agreement and the diagnostic performance in F-sodium fluoride (F-NaF) PET/computed tomography (CT) for the detection of skull-base bone invasion (SBBI) and osseous metastases in patients with newly diagnosed nasopharyngeal carcinoma (NPC).

METHODS

One hundred seventeen patients with newly diagnosed NPC between 2017 and 2019 who underwent F-NaF PET/CT was in included. Two experienced observers independently evaluated the F-NaF PET/CT of SBBI and osseous metastases on a patient level using a two-category scale present on a dichotomous scale, respectively. On a patient level, the diagnostic performance was calculated using a sensitivity analysis.

RESULTS

The interobserver agreement on a patient level of SBBI and osseous metastases were perfect on a patient-level (κ: 0.85), (κ: 0.808), respectively. On a lesion level of detection of osseous metastases, the observers agreed on the number as well as the location of osseous metastases in 101 (86.3%) patients. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of detection of SBBI and osseous metastases were ranged 0.911-0.962, 0.921-0.974, 0.932-0.957, 0.962-0.986, and 0.841-0.923, and ranged 0.917-0.958, 0.899-0.957, 0.906-0.949, 0.863-0.936, and 0.939-0.970, respectively.

CONCLUSION

The interobserver agreement of F-NaF PET/CT for the detection of SBBI and osseous metastases in patients with NPC were both very high among trained observers. Moreover, the diagnostic performance of NaF PET/CT was satisfactory, rendering NaF PET/CT a robust tool in the diagnostic armamentarium.

Emerging radiotherapy technologies and trends in nasopharyngeal cancer

Technology has always driven advances in radiotherapy treatment. In this review, we describe the main technological advances in radiotherapy over the past decades for the treatment of nasopharyngeal cancer (NPC) and highlight some of the pressing issues and challenges that remain. We aim to identify emerging trends in radiation medicine. These include advances in personalized medicine and advanced imaging modalities, standardization of planning and delineation, assessment of treatment response and adaptive re‐planning, impact of particle therapy, and role of artificial intelligence or automation in clinical care. In conclusion, we expect significant improvement in the therapeutic ratio of radiotherapy treatment for NPC over the next decade.

Comparison of rigid and deformable image registration for nasopharyngeal carcinoma radiotherapy planning with diagnostic position PET/CT

PURPOSE

This observer study aimed to compare rigid image registration (RIR) with deformable image registration (DIR) for diagnostic position (DP) positron emission tomography/computed tomography (PET/CT) images in the delineation of gross tumor volumes (GTVs) in nasopharyngeal carcinoma (NPC) radiotherapy planning.

MATERIALS AND METHODS

Four radiation oncologists individually delineated the GTVs, GTV_RIR, and GTV_DIR, on planning CT (pCT) images registered with DP-PET/CT images using RIR and B-spline-based DIR, respectively. Reference GTVs were independently delineated by all radiation oncologists using radiotherapy position (RP)-PET/CT images. DP- and RP-PET/CT images for 14 patients with NPC were acquired using early and delayed scans, respectively. Dice's similarity coefficient (DSC), mean distance to agreement, and volume agreement with reference GTVs were compared by considering the interobserver variability in reference contours.

RESULTS

The average DSCs for GTV_RIR and GTV_DIR were 0.77 and 0.77, which were acceptable for GTV delineation. There were no statistically significant differences between GTV_RIR and GTV_DIR in all evaluation indexes (p > 0.05). Furthermore, the correlation between neck flexion angle differences and GTV accuracy was not statistically significant (p > 0.05).

CONCLUSION

RIR was a feasible choice compared with the B-spline-based DIR in GTV delineation for NPC under variations of neck flexion angle.

Preliminary clinical results for PET/MR compared with PET/CT in patients with nasopharyngeal carcinoma

The present study aimed to assess the performance of positron emission tomography-magnetic resonance imaging (PET/MR) for the visualization and characterization of lesions. In addition, the present study investigated whether the apparent diffusion coefficient (ADC) and intravoxel incoherent motion parameters exhibited any significant correlation with standardized uptake values (SUV) in patients with nasopharyngeal carcinoma (NPC). A total of 35 patients with NPC underwent whole body PET-computed tomography (CT) and head and neck MR imaging (MRI) scans using the PET/CT-MRI system. Image quality, lesion conspicuity and the diagnostic confidence of PET/CT, T1 weighted (T1w) PET/MR and T2w PET/MR imaging were assessed. The true diffusion coefficient (D), the pseudo-diffusion coefficient or diffusion within the microcirculation (D*), and the perfusion fraction or the contribution of water moving in the capillaries (f), and ADC, were calculated. The correlation between the ADC, D*, D and f values and the SUV were analyzed using Pearson's correlation analysis. Similar image quality was obtained using PET/CT, T1w PET/MR and T2w PET/MR imaging. However, the T1w PET/MR and T2w PET/MR imaging were more effective than PET/CT in analyzing the lesion conspicuity of the primary tumors and lymph nodes. In addition, T2w PET/MR imaging was more efficient than T1w PET/MR imaging in analyzing primary tumors and lymph nodes. Pearson's correlation analysis showed no significant correlation between the SUV and ADC, and D*, D and f values in NPC. The present results suggested that the application of PET/MR is feasible and could serve as a reliable alternative to PET/CT, while SUV and ADC, D*, D and f values were identified as independent biomarkers in NPC.

Efficacy of endoscopy in assessing the local disease response in nasopharyngeal carcinoma patients after treated with intensity-modulated radiotherapy

AIM

The optimal local disease assessment after intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC) patients remains unclear. Our aim was to investigate the efficacy of post-IMRT endoscopies.

METHODS

The medical record of NPC patients with IMRT treatments during 2013 to 2015 was reviewed. Endoscopies and nasopharyngeal biopsies were performed at 6 weeks post-IMRT. Second biopsies were performed 4 weeks later for patients with abnormal first biopsies. Results of endoscopic assessments were correlated with histology using standard descriptive statistics.

RESULTS

A total of 262 patients were reviewed. Endoscopy showed a sensitivity, specificity, positive predictive value, and negative predictive value (NPV) of 71%, 90%, 41% and 97%, respectively. Disease remission at 6 weeks was observed in 234 patients (89.3%). Sixteen patients (6.1%) had ultimate disease remission (late responders) and 12 (4.6%) had persistent local disease.

CONCLUSION

Endoscopy had high specificity and NPV; therefore, invasive biopsy could be exempted in case of normal endoscopy.

Role of [18F] Fluoro-2-Deoxy-D-Glucose Positron Emission Tomography/Computed Tomography in the Diagnosis of Tonsillar Carcinoma in a Patient with Multiple Primary Carcinomas

Tonsillar carcinoma is not easily diagnosed on [¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) scan; normal, inflamed, and infected tonsils also exhibit increased tracer uptake. We present a case of a 68-year-old male with colon and prostate carcinomas who was referred for a PET/CT scan. He presented with right cervical lymphadenopathy which, on fine-needle biopsy, was found to have atypical cells suspicious for malignancy. On PET/CT, the right cervical lymph nodes appeared hypermetabolic; subsequent excision biopsy revealed metastatic poorly differentiated carcinoma. Increased metabolic activity was also seen in the tonsils, the right more than the left, which was initially ascribed to be inflammatory or physiologic. On magnetic resonance imaging follow-up, however, a more prominent and more enhancing right palatine tonsil was observed, which on histopathology was consistent with squamous cell carcinoma. Determining the maximum standard uptake value ratio between the two tonsils could have been helpful in differentiating squamous cell tonsillar carcinoma from benign asymmetric FDG uptake in this case. On a background of enlarged cervical lymph nodes and known primary carcinomas, uptake in the tonsils should be thoroughly assessed before interpreting it as an inflammatory or physiologic variant, especially if there is asymmetry in FDG uptake.

Diagnostic value of diffusion-weighted magnetic resonance imaging for local and skull base recurrence of nasopharyngeal carcinoma after radiotherapy

Tumor recurrence is a major cause of nasopharyngeal carcinoma (NPC) treatment failure. Diffusion-weighted imaging (DWI) is used for a variety of cancers, but few data are available for NPC.The aim of the study was to investigate the DWI features of recurrent NPC after radiotherapy and apparent diffusion coefficient (ADC) thresholds for the diagnosis of recurrent NPC.This was a retrospective study of 160 patients with NPC treated by radiotherapy at the Cancer Hospital affiliated to Guangxi Medical University from May 2012 to March 2015. The patients were divided into the local recurrence (n = 39), fibrosis (n = 51), clivus recurrence (n = 22), and clivus nonrecurrence (n = 48) groups. The patients underwent magnetic resonance imaging (MRI), enhanced MRI, and DWI. Receiver operating characteristics curves were used to determine sensitivity, specificity, and negative predictive values.ADC values were significantly different between the recurrence and fibrosis groups (P < .0001). Using ADC threshold values of 0.887 × 10 mm/s for local recurrence, the area under the curve (AUC) of DWI was 0.967 (87.2% sensitivity and 94.1% specificity), compared with 0.732 for routine MRI (71.8% sensitivity and 74.5% specificity) (P < .001). Using ADC threshold values of 1.018 × 10 mm/s for the diagnosis of clivus recurrent NPC, the AUC of DWI was 0.984 (95.5% sensitivity and 91.7% specificity) compared with 0.558 for routine MRI (63.6% sensitivity and 47.9% specificity) (P < .001).DWI has a higher diagnostic value for recurrent NPC than MRI. DWI can increase the diagnosis sensitivity and specificity of locally recurrent NPC.

Childhood Nasopharyngeal Carcinoma: State-of-the-Art, and Questions for the Future

In children, nasopharyngeal carcinoma (NPC) is a very rare tumor, mostly Epstein-Barr Virus related and quite always diagnosed at a locally advanced stage. With current protocols associating induction cisplatin-based chemotherapy and concomitant chemoradiotherapy, prognosis is excellent with overall survival higher than 85%. However, long-term toxicities are frequent. Improvement in radiation therapy modalities like intensity-modulated radiation therapy and new strategies with radiation dose adaptation to chemotherapy response have been introduced to reduce acute and long-term toxicities. Actually, 2 main questions remain: is it possible to pursue a therapeutic deescalation in children with low-risk NPC or very good response to induction chemotherapy in order to reduce the risk of late effects? Could an immunologic maintenance treatment improve prognosis of children with high-risk NPC? International collaborative groups and prospective trials including biological studies are necessary to answer these questions to improve childhood NPC treatment and knowledge.

Junior E, Machado AM, Mamede M. Individualized threshold for tumor segmentation in 18F-FDG PET/CT imaging: The key for response evaluation of neoadjuvant chemoradiation therapy in patients with rectal cancer?

Summary Introduction: The standard treatment for locally advanced rectal cancer (RC) consists of neoadjuvant chemoradiation followed by radical surgery. Regardless the extensive use of SUVmax in 18F-FDG PET tumor uptake as representation of tumor glycolytic consumption, there is a trend to apply metabolic volume instead. Thus, the aim of the present study was to evaluate a noninvasive method for tumor segmentation using the 18F-FDG PET imaging in order to predict response to neoadjuvant chemoradiation therapy in patients with rectal cancer. Method: The sample consisted of stage II and III rectal cancer patients undergoing 18F-FDG PET/CT examination before and eight weeks after neoadjuvant therapy. An individualized tumor segmentation methodology was applied to generate tumor volumes (SUV2SD) and compare with standard SUVmax and fixed threshold (SUV40%, SUV50% and SUV60%) pre- and post-therapy. Therapeutic response was assessed in the resected specimens using Dworak's protocol recommendations. Several variables were generated and compared with the histopathological results. Results: Seventeen (17) patients were included and analyzed. Significant differences were observed between responders (Dworak 3 and 4) and non-responders for SUVmax-2 (p<0.01), SUV2SD-2 (p<0.05), SUV40%-2 (p<0.05), SUV50%-2 (p<0.05) and SUV60%-2 (p<0.05). ROC analyses showed significant areas under the curve (p<0.01) for the proposed methodology with sensitivity and specificity varying from 60% to 83% and 73% to 82%, respectively. Conclusion: The present study confirmed the predictive power of the variables using a noninvasive individualized methodology for tumor segmentation based on 18F-FDG PET/CT imaging for response evaluation in patients with rectal cancer after neoadjuvant chemoradiation therapy.

Nasopharyngeal carcinoma presenting as an inconspicuous primary lesion with extensive cavernous sinus involvement and temporal lobe extension: a case report and review of literature

Detection of nodal metastasis in the neck or adjacent structures is common in nasopharyngeal carcinoma (NPC) when there is frank primary disease. Intracranial extension without obvious nasopharyngeal disease is not common. Here, we discuss a patient with NPC that presented with extensive intracranial disease with subtle findings in the nasopharynx.

Prognostic value of 18F-fluorodeoxyglucose PET parameters and inflammation in patients with nasopharyngeal carcinoma

The aim of the present study was to investigate the association between positron emission tomography (PET) parameters and peripheral inflammatory markers, and assess their prognostic value in nasopharyngeal carcinoma (NPC). A total of 121 patients with non-disseminated NPC were recruited. Pretreatment maximum standardized uptake values (SUVmax) of PET and peripheral inflammatory factors (leukocyte, neutrophil and monocyte counts) were recorded. Kaplan-Meier and multivariate analyses were used to identify predictors for progression-free survival (PFS), overall survival (OS), distant metastasis-free survival (DMFS) and locoregional recurrence-free survival (LRFS). The results of the present study revealed that SUVmax at the primary tumor was positively correlated with leukocytes (P=0.025), neutrophils (P=0.009) and monocytes (P=0.043). SUVmax at regional lymph nodes (SUVmax-N) was significantly associated with monocytes (P=0.024). Kaplan-Meier analysis demonstrated that SUVmax-N (>10.15) significantly predicted PFS (P=0.004) and DMFS (P=0.003). In addition, neutrophils (>5.18) were significantly associated with PFS (P=0.001), DMFS (P=0.013) and LRFS (P<0.001). Multivariate analysis revealed that SUVmax-N and neutrophils retained independent prognostic significance for PFS (SUVmax-N, P=0.026; and neutrophils, P=0.033) and DMFS (SUVmax-N, P=0.026; and neutrophils, P=0.032). Furthermore, patients with SUVmax-N ≤10.15 and neutrophils ≤5.18 had significantly improved prognosis in PFS (96.4 vs. 58.5%, P<0.001), OS (95.7 vs. 81.1%, P=0.044), DMFS (96.4 vs. 67.0%, P<0.001) and LRFS (100 vs. 90.2%, P=0.036) compared with those with SUVmax-N >10.15 or neutrophils >5.18. In conclusion, SUVmax may be significantly associated with cancer-associated inflammation. SUVmax-N and neutrophils were independent prognostic indicators for PFS and DMFS. Combined assessment of SUVmax-N and neutrophils may lead to refinement of risk stratification in NPC.

Prognostic value of pretreatment 18F-FDG PET-CT for nasopharyngeal carcinoma patients

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a special subtype of head and neck cancer (HNC). At present, there are no highly specific prognostic markers to aid in tumor grading and guide patient treatment modalities for NPC. The prognostic value of pretreatment F-fluorodeoxyglucose positron emission tomography-computed tomography (F-PET-CT) in NPC patients is controversial and no consensus exists as to its predictive capability.

METHODS

To analyze the predictive efficacy of F-PET-CT imaging in NPC patients, data from MEDLINE, EMBASE, the Cochrane library, CBM, CNKI, and VIP (inception to July 2016) were accessed. Results from prospective and retrospective observational studies that used F-FDG PET to predict disease prognosis in NPC patients were used for analysis. Two authors independently assessed study quality and extracted data. Event-free survival (EFS) was considered the primary endpoint and overall survival rate (OS) was considered the secondary endpoint.

RESULTS

Data from 14 studies and 1134 patients were included in our analysis. The hazard ratios (HRs) of maximum standardized uptake value of primary tumor (SUVmax-T), metabolic tumor volume of primary tumor (MTV-T), and total lesional glycolysis of primary tumor (TLG-T) for EFS were 1.31 (95% confidence interval [CI], 1.11-1.55, P = .001), 2.38 (95% CI 1.53-3.70, P < .001), and 1.65 (95% CI 0.76-3.59, P = .21), respectively. Among studies including TLG-T, those with a fixed SUV of 2.5 had an HR of 3.55 (95% CI, 1.42-8.84, P = .007). The HRs of SUVmax-T and MTV-T for OS were 2.19 (95% CI, 1.47-3.27, P < .001) and 2.69 (95% CI, 1.01-7.17, P = .05), respectively. Among studies including MTV-T, those with a fixed SUV of 2.5 had an HR of 4.07 (95% CI, 2.22-7.46, P < .001). Tests used for assessing predictive value of pretreatment SUVmax, MTV, and TLG of lymph nodes for EFS and OS showed that these parameters did not have significant predictive value (P>.05).

CONCLUSION

Our results suggested that SUVmax, MTV, and TLG (with a fixed SUV of 2.5) of primary tumors before treatment initiation may be independent prognostic factors for NPC patients; however, SUVmax, MTV, and TLG of metastatic lymph nodes are not.

Whole-body 18F-FDG PET/CT for M staging in the patient with newly diagnosed nasopharyngeal carcinoma: Who needs?

OBJECTIVE

Although whole-body fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) (¹⁸F-FDG PET/CT) is commonly used for M staging of newly diagnosed nasopharyngeal carcinoma (NPC), some patients may not benefit from this procedure. The present study investigated which patients require this modality for M staging.

METHODS

Whole-body ¹⁸F FDG PET/CT results and clinical data were collected for 264 patients with newly diagnosed NPC. The relationships between distant metastasis and age, gender, pathological type, lesion size, SUVmax-T, T staging, N staging, SUVmax-N and Epstein-Barr virus (EBV) quantity were retrospectively analysed to identify factors associated with increased risk.

RESULTS

Of the 264 patients, only 37 (14.0%) were diagnosed with distant metastasis. Using multiple logistic regression analysis, EBV-positivity (OR=13.1; 95% CI:1.61,106.80), N staging (OR=3.05; 95% CI:1.41,6.63) and T staging (OR=2.16; 95% CI:1.10, 4.24) were significantly related to distant metastasis (all P<0.05). EBV DNA levels≥9000copies/ml, N3 stage and T4 stage were identified as high risk factors. A low risk of distant metastasis was found in patients with 0-1 risk factors and in those with 2 specific risk factors, T3/T4 and N2/N3 staging. Patients with EBV DNA levels ≥9000copies/ml and N3 or T4 staging and those with 3 risk factors had a medium or high risk, with a much higher incidence of distant metastasis (χ²=29.896, P=0.000), and needed a whole-body ¹⁸F FDG PET/CT for M staging.

CONCLUSIONS

Due to the low incidence of distant metastasis, only patients with medium or high risk need to undergo a whole-body scan.

Value of 18F-FDG heterogeneity for discerning metastatic from benign lymph nodes in nasopharyngeal carcinoma patients with suspected recurrence

OBJECTIVE

This study investigated the value of fluorine-18 fludeoxyglucose (¹⁸F-FDG) heterogeneity as an indicator of metastatic lymph nodes (LNs) in patients with nasopharyngeal carcinoma (NPC). We further assessed whether addition of this parameter improves diagnostic performance beyond that provided by maximum standardized uptake value (SUV_max).

METHODS

We analyzed 74 LNs that were suspicious for metastasis. These LNs were measured for coefficient of variation (CV) of ¹⁸F-FDG uptake, which was used as a parameter for ¹⁸F-FDG heterogeneity.

RESULTS

Multivariate logistic regression analyses revealed that a high CV (hazard ratio, 20.97; 95% confidence interval, 2.26-194.62; p = 0.007) was an independent predictor of metastatic LNs. However, receiver-operating characteristic curve analysis (p = 0.278) and net reclassification (p = 0.539) were unable to show improved diagnostic performance by addition of CV to SUV_max.

CONCLUSION

High CV of ¹⁸F-FDG uptake is an independent risk factor for metastatic LNs in patients with NPC displaying suspicious LNs following treatment. Advances in knowledge: Heterogeneity of ¹⁸F-FDG uptake has a potential as a biomarker of metastatic LNs.

(18)F-FDG Uptake Characteristics in Differentiating Benign from Malignant Nasopharyngeal Lesions in Children

The characteristics of FDG uptake in the physiologic and malignant nasopharynx were investigated in the paper which was correlated with either pathologic findings or clinical follow-up. Three patients had pathologically established nasopharyngeal malignancy. In the 3 nasopharyngeal malignancies, 2 had diffusely and expansively increased FDG uptake, and one had asymmetric uptake. Our results indicated that the difference between adenoid hypertrophy and malignancy is asymmetric or diffusely expansive ¹⁸F-FDG uptake with or without correlating morphologic lesion on diagnostic CT in children under 10 years of age. The typical characteristics of physiologic and inflammatory ¹⁸F-FDG uptake in nasopharynx are symmetrically trapezoid. Diffusely increased nasopharyngeal FDG uptake can be considered physiologic if SUV_max is less than 7.6 but should be carefully assessed by pharyngorhinoscopy if SUV_max is greater than 11 and there is no correlating morphologic lesion on diagnostic CT. The diffusely, expansively increased uptake, and asymmetric uptake in particular, should be considered as malignancy. Further biopsy is especially indicated in patients with retropharyngeal space and bilateral cervical lymph node abnormality but no history of malignancy.

False-positive finding of retropharyngeal lymph node recurrence in both fluorine (18)FDG PET and MRI in a patient with nasopharyngeal carcinoma

BACKGROUND

Biopsy of the retropharyngeal node is not routinely accessible. The diagnosis of retropharyngeal lymph node recurrence in patients with nasopharyngeal carcinoma (NPC) is often based on an imaging study.

METHODS

We reported a patient with NPC who was incorrectly diagnosed with left retropharyngeal lymph node recurrence by both MRI and positron emission tomography (PET)/CT.

RESULTS

A woman who was treated for stage IVA NPC 2 years previously was found to have a nodal lesion in the left retropharyngeal space on MRI together with focal fluorodeoxyglucose (FDG) uptake on PET/CT. Locoregional recurrence was suspected, and surgery was performed. Subsequent pathology results showed reactive lymphoid hyperplasia.

CONCLUSION

Although tissue biopsy for the retropharyngeal node is technically difficult, this case demonstrates that tumor recurrence cannot be diagnosed even based on both positive findings on MRI and PET/CT in patients with NPC.