Nasopharyngeal carcinoma: relationship between 18F-FDG PET-CT maximum standardized uptake value, metabolic tumour volume and total lesion glycolysis and TNM classification

Deep learning techniques in PET/CT imaging: A comprehensive review from sinogram to image space

Positron emission tomography/computed tomography (PET/CT) is increasingly used in oncology, neurology, cardiology, and emerging medical fields. The success stems from the cohesive information that hybrid PET/CT imaging offers, surpassing the capabilities of individual modalities when used in isolation for different malignancies. However, manual image interpretation requires extensive disease-specific knowledge, and it is a time-consuming aspect of physicians' daily routines. Deep learning algorithms, akin to a practitioner during training, extract knowledge from images to facilitate the diagnosis process by detecting symptoms and enhancing images. This acquired knowledge aids in supporting the diagnosis process through symptom detection and image enhancement. The available review papers on PET/CT imaging have a drawback as they either included additional modalities or examined various types of AI applications. However, there has been a lack of comprehensive investigation specifically focused on the highly specific use of AI, and deep learning, on PET/CT images. This review aims to fill that gap by investigating the characteristics of approaches used in papers that employed deep learning for PET/CT imaging. Within the review, we identified 99 studies published between 2017 and 2022 that applied deep learning to PET/CT images. We also identified the best pre-processing algorithms and the most effective deep learning models reported for PET/CT while highlighting the current limitations. Our review underscores the potential of deep learning (DL) in PET/CT imaging, with successful applications in lesion detection, tumor segmentation, and disease classification in both sinogram and image spaces. Common and specific pre-processing techniques are also discussed. DL algorithms excel at extracting meaningful features, and enhancing accuracy and efficiency in diagnosis. However, limitations arise from the scarcity of annotated datasets and challenges in explainability and uncertainty. Recent DL models, such as attention-based models, generative models, multi-modal models, graph convolutional networks, and transformers, are promising for improving PET/CT studies. Additionally, radiomics has garnered attention for tumor classification and predicting patient outcomes. Ongoing research is crucial to explore new applications and improve the accuracy of DL models in this rapidly evolving field.

Prognostic value of primary tumor and lymph node volumetric metabolic parameters at pre-treatment F-18 FDG PET/CT in nasopharyngeal carcinoma

BACKGROUND

The aim of this study was to evaluate the prognostic significance of volumetric metabolic parameters of pre-treatment PET/CT along with clinical characteristics in patients with non-metastatic nasopharyngeal carcinoma.

MATERIAL AND METHODS

Seventy-nine patients with nasopharyngeal carcinoma underwent F18- FDG PET/CT for pretreatment evaluation and included in this study. The patient features (patient age, tumor histopathology, T and N stage, size of primary tumor and the largest cervical lymph node) and PET parameters were analyzed: maximum, mean and peak standardized uptake values (SUVmax, SUVmean, SUVpeak), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for primary tumor and largest cervical lymph node. After treatment, patients were evaluated for disease progression and mortality. Survival analysis for progression-free survival (PFS) and over-all survival (OS) was performed with Kaplan-Meier method using PET findings and clinical characteristics.

RESULTS

The median follow-up duration was 29.7 months (range 3-125 months). Among clinical characteristics, no parameters had significance association for PFS. Primary tumor-MTV and cervical lymph node-MTV were independent prognostic factors for PFS (p = 0.025 and p = 0.004, respectively).Patients with primary tumor-MTV >19.4 and patients with lymph node-MTV>3.4 had shorter PFS. For OS, age and the size of the lymph node were independent prognostic factor (p = 0.031 and p = 0.029).Patients with age over 54 years and patients with lymph node size >1 cm were associated with decreased OS.

CONCLUSION

Primary tumor-MTV and lymph node-MTV on pre-treatment PET/CT are significant prognostic factors for long-term PFS in non-metastatic nasopharyngeal carcinoma. We consider that measuring MTV as volume-based metabolic parameter on pretreatment PET/CT may contribute decision of treatment intensity and individualized risk stratification and may improve long-term PFS. Additionally, age and the size of lymph node are independent prognostic factors for mortality.

The valuable role of dynamic 18F FDG PET/CT-derived kinetic parameter Ki in patients with nasopharyngeal carcinoma prior to radiotherapy: A prospective study

BACKGROUND AND PURPOSE

Dynamic positron emission tomography/computed tomography (PET/CT) served the potential role of characterizing malignant foci. The main objective of this prospective study was to explore the advantage of dynamic PET/CT imaging in characterizing nasopharyngeal carcinoma (NPC).

METHODS AND MATERIALS

Patients with probable head and neck disease underwent a local dynamic PET/CT scan followed by a whole-body static scan. Patlak analysis was used to generate parametric influx rate constant (K_i) images from 48 frames obtained from a dynamic PET/CT scan. By delineating the volumes-of-interest (VOIs) of: primary tumor (PT), lymph node (LN), and normal nasopharyngeal tissues (N), we acquired the corresponding K_i mean and SUVmean of each site respectively to perform the quantitative statistical analysis.

RESULTS

Qualified images of 71 patients with newly diagnosed NPC and 8 without nasopharyngeal malignant lesions were finally included. We found the correlations between K_i mean-PT and critical clinical features, including clinical stage (r = 0.368), T category (r = 0.643) and EBV-DNA copy status (r = 0.351), and K_i mean-PT differed within the group. SUVmean-PT showed correlations with clinical stage (r = 0.280) and T category (r = 0.472), but could hardly differ systematically within group of clinical features except T category. K_i mean-LN offered the positive correlations with N category (r = 0.294), M category (r = 0.238) and EBV-DNA copy status (r = 0.446), and differed within the group. In addition, K_i mean represented a sensitivity of 94.4 % and a specificity of 100 %, in distinguishing NPC from the non-NPC, when the cut-off was defined as 0.0106. When the cut-off of SUV being defined as 2.03, the sensitivity and specificity were both 100 %.

CONCLUSION

Our research confirmed K_i compared favorably to SUV in characterizing NPC and found that K_i can serve as an effective imaging marker of NPC.

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.

Focal Nasopharyngeal Activity Detected on [18F]FDG PET/CT: Clinical Implications and Comparison of Metabolic Parameters for Prediction of Malignancy

Purpose

We aimed to investigate the incidence and clinical significance of incidental focal nasopharyngeal uptake on [18F]FDG PET/CT and to evaluate the diagnostic performance of various metabolic parameters to differentiate between benign and malignant nasopharyngeal lesions.

Methods

A total of 63 consecutive patients with incidental focal nasopharyngeal uptake on [18F]FDG PET/CT and subsequent nasopharyngeal biopsy were retrospectively enrolled. In addition, baseline pretherapeutic [18F]FDG PET/CT images of 59 patients with newly diagnosed pathologically proven nasopharyngeal carcinoma (NPC) were reviewed. Maximum standardized uptake value (SUVmax), mean SUV (SUVmean), nasopharynx-to-palatine tonsil ratio (NPR), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the nasopharyngeal lesions were determined. Receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic performance of the metabolic parameters.

Results

Incidental focal nasopharyngeal uptake in two patients (3.2%, 2/63) was pathologically confirmed to be NPC. All the metabolic parameters (SUVmax, SUVmean, NPR, MTV, and TLG) demonstrated significantly greater values in patients with NPC compared with patients with benign or physiological nasopharyngeal uptake (p < 0.001). Among the metabolic parameters, NPR demonstrated the greatest area under the curve of 0.992 (p < 0.05), with a sensitivity of 96.7% and a specificity of 93.4% when a cut-off of 1.1 was used. Similar results were seen in nasopharyngeal lesions without morphological abnormality.

Conclusion

NPC is an infrequent but important cause of incidental focal nasopharyngeal uptake on [18F]FDG PET/CT. Metabolic parameters were shown to be useful to differentiate between benign and malignant nasopharyngeal lesions, and NPR showed the best diagnostic performance.

Correlation between Tissue Cellularity and Metabolism Represented by Diffusion-Weighted Imaging (DWI) and 18F-FDG PET/MRI in Head and Neck Cancer (HNC)

Simple Summary

We report on the correlation between the diffusion-weighted imaging (DWI) and the metabolic volume parameters derived from a PET scan, to determine the correlation between these parameters and the tumor cellularity in head and neck primary tumors. Our findings implied that there was no correlation between the information derived from the DWI and the information derived from the FDG metabolic parameters. Thus, both imaging techniques might play a complementary role in HNC diagnosis and assessment. This is significant because the treatment plan of patients with HNC should be well evaluated by using all the available diagnosis techniques, for a better understanding of how the tumor will react.

Abstract

Background: This study aimed to assess the association of 18F-Fluorodeoxyglucose positron-emission-tomography (18F-FDG/PET) and DWI imaging parameters from a primary tumor and their correlations with clinicopathological factors. Methods: We retrospectively analyzed primary tumors in 71 patients with proven HNC. Primary tumor radiological parameters: DWI and FDG, as well as pathological characteristics were analyzed. Spearman correlation coefficient was used to assess the correlation between DWI and FDG parameters, ANOVA or Kruskal–Wallis, independent sample t-test, Mann–Whitney test, and multiple regression were performed on the clinicopathological features that may affect the 18F- FDG and apparent-diffusion coefficient (ADC) of the tumor. Results: No significant correlations were observed between DWI and any of the 18F-FDG parameters (p > 0.05). SUVmax correlated with N-stages (p = 0.023), TLG and MTV correlated with T-stages (p = 0.006 and p = 0.001), and ADC correlated with tumor grades (p = 0.05). SUVmax was able to differentiate between N+ and N− groups (p = 0.004). Conclusions: Our results revealed a non-significant correlation between the FDG-PET and ADC-MR parameters. FDG-PET-based glucose metabolic and DWI-MR-derived cellularity data may represent different biological aspects of HNC.

Prognostic value of tumor metabolic imaging phenotype by FDG PET radiomics in HNSCC

OBJECTIVE

Tumor metabolic phenotype can be assessed with integrated image pattern analysis of 18F-fluoro-deoxy-glucose (FDG) Positron Emission Tomography/Computed Tomography (PET/CT), called radiomics. This study was performed to assess the prognostic value of radiomics PET parameters in head and neck squamous cell carcinoma (HNSCC) patients.

METHODS

18F-fluoro-deoxy-glucose (FDG) PET/CT data of 215 patients from HNSCC collection free database in The Cancer Imaging Archive (TCIA), and 122 patients in Seoul St. Mary's Hospital with baseline FDG PET/CT for locally advanced HNSCC were reviewed. Data from TCIA database were used as a training cohort, and data from Seoul St. Mary's Hospital as a validation cohort. With the training cohort, primary tumors were segmented by Nestles' adaptive thresholding method. Segmental tumors in PET images were preprocessed using relative resampling of 64 bins. Forty-two PET parameters, including conventional parameters and texture parameters, were measured. Binary groups of homogeneous imaging phenotypes, clustered by K-means method, were compared for overall survival (OS) and disease-free survival (DFS) by log-rank test. Selected individual radiomics parameters were tested along with clinical factors, including age and sex, by Cox-regression test for OS and DFS, and the significant parameters were tested with multivariate analysis. Significant parameters on multivariate analysis were again tested with multivariate analysis in the validation cohort.

RESULTS

A total of 119 patients, 70 from training, and 49 from validation cohort, were included in the study. The median follow-up period was 62 and 52 months for the training and the validation cohort, respectively. In the training cohort. binary groups with different metabolic radiomics phenotypes showed significant difference in OS (p = 0.036), and borderline difference in DFS (p = 0.086). Gray-Level Non-Uniformity for zone (GLNUGLZLM) was the most significant prognostic factor for both OS (hazard ratio [HR] 3.1, 95% confidence interval [CI] 1.4-7.3, p = 0.008) and DFS (HR 4.5, CI 1.3-16, p = 0.020). Multivariate analysis revealed GLNUGLZLM as an independent prognostic factor for OS (HR 3.7, 95% CI 1.1-7.5, p = 0.032). GLNUGLZLM remained as an independent prognostic factor in the validation cohort (HR 14.8. 95% CI 3.3-66, p < 0.001).

CONCLUSIONS

Baseline FDG PET radiomics contain risk information for survival prognosis in HNSCC patients. The metabolic heterogeneity parameter, GLNUGLZLM, may assist clinicians in patient risk assessment as a feasible prognostic factor.

Prognostic value of maximum standard uptake value, metabolic tumor volume, and total lesion glycolysis of positron emission tomography/computed tomography in patients with nasopharyngeal carcinoma: A systematic review and meta-analysis

BACKGROUND

The maximal standard uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of positron emission tomography/computed tomography (PET/CT) in patients with nasopharyngeal carcinoma (NPC) perform as new prognostic factors, but the outcomes of the published articles were inconclusive. In this meta-analysis, we evaluated the prognostic value of SUVmax, MTV, and TLG of PET/CT in patients with NPC.

METHODS

Relevant English articles were searched in PubMed and EMBASE. The data of patients and the survival outcomes were extracted. Pooled hazard ratios (HRs) were accounted to assess the prognostic value of the SUVmax, MTV, and TLG.

RESULTS

This meta-analysis combined 10 primary studies including 941 patients with NPC. The combined HRs (95% confidence interval [CI] of higher SUVmax, higher MTV, and higher TLG for event-free survival were 2.33 (95% CI, 1.39-3.91, P = .001), 2.51 (95% CI, 1.61-3.91, P < .0001), and 2.74 (95% CI, 1.91-3.93, P < .00001), respectively. Regarding overall survival, the combined HRs were 2.50 (95%CI, 1.65-3.78, P < .0001) with higher SUVmax, 3.30 (95% CI, 1.92-5.69, P < .0001) with higher MTV and 3.18 (95% CI, 1.70-5.96, P = .0003) with higher TLG.

CONCLUSION

SUVmax, MTV, and TLG were significant prognostic predictors in patients with NPC. And the results suggested that higher SUVmax, MTV, and TLG were associated with worse prognosis.

[(18)F]FDG-PET/CT metabolic parameters as useful prognostic factors in cervical cancer patients treated with chemo-radiotherapy

Background

To compare the prognostic value of different anatomical and functional metabolic parameters determined using [¹⁸F]FDG-PET/CT with other clinical and pathological prognostic parameters in cervical cancer (CC).

Methods

Thirty-eight patients treated with standard curative doses of chemo-radiotherapy (CRT) underwent pre- and post-therapy [¹⁸F]FDG-PET/CT. [¹⁸F]FDG-PET/CT parameters including mean tumor standardized uptake values (SUV), metabolic tumor volume (MTV) and tumor glycolytic volume (TGV) were measured before the start of CRT. The post-treatment tumor metabolic response was evaluated. These parameters were compared to other clinical prognostic factors. Survival curves were estimated by using the Kaplan-Meier method. Cox regression analysis was performed to determine the independent contribution of each prognostic factor.

Results

After 37 months of median follow-up (range, 12–106), overall survival (OS) was 71 % [95 % confidence interval (CI), 54–88], disease-free survival (DFS) 61 % [95 % CI, 44–78] and loco-regional control (LRC) 76 % [95 % CI, 62–90]. In univariate analyses the [¹⁸F]FDG-PET/CT parameters unfavorably influencing OS, DFS and LRC were pre-treatment TGV-cutoff ≥562 (37 vs. 76 %, p = 0.01; 33 vs. 70 %, p = 0.002; and 55 vs. 83 %, p = 0.005, respectively), mean pre-treatment tumor SUV cutoff ≥5 (57 vs. 86 %, p = 0.03; 36 vs. 88 %, p = 0.004; 65 vs. 88 %, p = 0.04, respectively) and a partial tumor metabolic response after treatment (9 vs. 29 %, p = 0.0008; 0 vs. 83 %, p < 0.0001; 22 vs. 96 %, p < 0.0001, respectively). After multivariate analyses a partial tumor metabolic response after treatment remained as an independent prognostic factor unfavorably influencing DFS and LRC (RR 1:7.7, p < 0.0001, and RR 1:22.6, p = 0.0003, respectively) while the pre-treatment TGV-cutoff ≥562 negatively influenced OS and DFS (RR 1:2, p = 0.03, and RR 1:2.75, p = 0.05).

Conclusions

Parameters capturing the pre-treatment glycolytic volume and metabolic activity of [¹⁸F]FDG–positive disease provide important prognostic information in patients with CC treated with CRT. The post-therapy [¹⁸F]FDG-PET/CT uptake (partial tumor metabolic response) is predictive of disease outcome.

The Clinical Usefulness of (18)F-Fluorodeoxyglucose Positron Emission Tomography (PET) to Predict Oncologic Outcomes and PET-Based Radiotherapeutic Considerations in Locally Advanced Nasopharyngeal Carcinoma

Purpose

We investigated ¹⁸F-fluorodeoxyglucose positron emission tomography (PET)-derived parameters as prognostic indices for disease progression and survival in locally advanced nasopharyngeal carcinoma (NPC) and the effect of high-dose radiotherapy for a subpopulation with PET-based poor prognoses.

Materials and Methods

Ninety-seven stage III and Iva-b NPC patients who underwent definitive treatment and PET were reviewed. For each primary, nodal, and whole tumor, maximum standardized uptake value, metabolic tumor volume, and total lesion glycolysis (TLG) were evaluated.

Results

Based on the C-index (0.666) and incremental area under the curve (0.669), the whole tumor TLGwas the most useful predictorfor progression-free survival (PFS); thewhole tumor TLG cut-off value showing the best predictive performance was 322.7. In multivariate analysis, whole tumor TLG was a significant prognostic factor for PFS (hazard ratio [HR], 0.3; 95% confidence interval [CI], 0.14 to 0.65; p=0.002) and OS (HR, 0.29; 95% CI, 0.11 to 0.79; p=0.02). Patients with low whole tumor TLG showed the higher 5-year PFS in the subgroup for only patients receiving intensity modulated radiotherapy (77.4% vs. 53.0%, p=0.01). In the subgroup of patients with high whole tumor TLG, patients receiving an EQD₂ ≥ 70 Gy showed significantly greater complete remission rates (71.4% vs. 33.3%, p=0.03) and higher 5-year OS (74.7% vs. 19.6%, p=0.02).

Conclusion

Our findings demonstrated that whole tumor TLG could be an independent prognostic factor and high-dose radiotherapy could improve outcomes for NPC showing high whole tumor TLG.

Obtaining quantitative global tumoral state indicators based on whole-body PET/CT scans: a breast cancer case study

OBJECTIVES

In this work we address the need for the computation of quantitative global tumoral state indicators from oncological whole-body PET/computed tomography scans. The combination of such indicators with other oncological information such as tumor markers or biopsy results would prove useful in oncological decision-making scenarios.

MATERIALS AND METHODS

From an ordering of 100 breast cancer patients on the basis of oncological state through visual analysis by a consensus of nuclear medicine specialists, a set of numerical indicators computed from image analysis of the PET/computed tomography scan is presented, which attempts to summarize a patient's oncological state in a quantitative manner taking into consideration the total tumor volume, aggressiveness, and spread.

RESULTS

Results obtained by comparative analysis of the proposed indicators with respect to the experts' evaluation show up to 87% Pearson's correlation coefficient when providing expert-guided PET metabolic tumor volume segmentation and 64% correlation when using completely automatic image analysis techniques.

CONCLUSION

Global quantitative tumor information obtained by whole-body PET/CT image analysis can prove useful in clinical nuclear medicine settings and oncological decision-making scenarios. The completely automatic computation of such indicators would improve its impact as time efficiency and specialist independence would be achieved.

The relationship between 18F-FDG metabolic volumetric parameters and clinicopathological factors of breast cancer

OBJECTIVES

This study was conducted to evaluate the relationship between fluorine-18 fluorodeoxyglucose metabolic parameters [maximum standardized uptake value (SUV(max)), metabolic tumor volume (MTV), and total lesion glycolysis (TLG)] and clinicopathological factors of breast cancer.

METHODS

The study comprised 93 patients. A volumetric region of interest was drawn over the abnormal focal uptake of breast cancer. Spearman's rank correlation, the Kruskal-Wallis test, and receiver operating characteristic analysis were used to investigate the relationship between clinicopathological factors and metabolic parameters and determine which metabolic parameters were most highly associated with clinicopathological factors.

RESULTS

All parameters had a statistically significant relationship with pathological T stage (p-T stage), pathological N status (p-N status), pathological stage (p-stage), and triple-negative type (TN) (all P values were <0.05). There were statistically significant differences between SUV(max) and TLG in relation to lymphatic invasion, estrogen receptor, and nuclear grade (P<0.05). High MTV showed a tendency toward association with estrogen receptor negativity, but the relation did not reach the level of statistical significance (P=0.056). No statistically significant relationship was observed between MTV and lymphatic invasion or nuclear grade. In the receiver operating characteristic analysis of p-T stage and p-stage, the AUC for TLG was significantly larger than that for SUV(max) (P=0.0003 and 0.048, respectively). There were marginally significant differences between TLG and MTV in relation to p-stage (P=0.058).

CONCLUSION

TLG may reflect tumor metabolism for clinicopathological factors of breast cancer better than SUV(max) or MTV.

Prognostic significance of volume-based PET parameters in cancer patients

Accurate prediction of cancer prognosis before the start of treatment is important since these predictions often affect the choice of treatment. Prognosis is usually based on anatomical staging and other clinical factors. However, the conventional system is not sufficient to accurately and reliably determine prognosis. Metabolic parameters measured by ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) have the potential to provide valuable information regarding prognosis and treatment response evaluation in cancer patients. Among these parameters, volume-based PET parameters such as metabolic tumor volume and total lesion glycolysis are especially promising. However, the measurement of these parameters is significantly affected by the imaging methodology and specific image characteristics, and a standard method for these parameters has not been established. This review introduces volume-based PET parameters as potential prognostic indicators, and highlights methodological considerations for measurement, potential implications, and prospects for further studies.

Prognostic value of quantitative parameters derived on initial staging 18F-fluorodeoxyglucose positron emission tomography/computed tomography in patients with high-grade non-Hodgkin's lymphoma

OBJECTIVES

This study was carried out to evaluate the role of quantitative parameters in staging PET in predicting prognosis in patients with high-grade non-Hodgkin's lymphoma (NHL).

METHODS

A total of 51 histopathologically proven high-grade NHL patients treated with conventional chemotherapy regimens were included in the study. Total lesion glycolysis (TLG) and functional volumes (FVs) were defined as per the PET Response Criteria in Solid Tumors (PERCIST) criteria. All patients were followed up for a minimum period of 1 year or until an event, whichever occurred earlier.

RESULTS

Of the four semiquantitative parameters studied, SUV max and SUV mean did not show a statistically significant correlation with progression-free survival or overall survival, whereas TLG and FV showed a weak but statistically significant negative correlation. Using the receiver operating characteristic curve analysis, optimal cut-offs were derived for FV and TLG to predict progression and death. Using the cut-off values of 416 cm3 and 3340 g for FV and TLG, respectively, a statistically significant difference in progression-free survival and overall survival was obtained in the groups with FV and TLG above and below the threshold. On multivariate analysis of all the conventional prognostic factors and TLG more than 3340 and FV more than 416 cm3, only age greater than 60 years (P=0.013) and FV more than 416 cm3 (P=0.012) were found to be independently associated with disease progression.

CONCLUSION

Our results indicate that FV and TLG in staging PET/CT could be useful indices in predicting outcomes in patients with high-grade NHL treated with standard first-line chemotherapy regimens.

Image-derived arterial input function in dynamic positron emission tomography-computed tomography: a method using both positron emission tomographic and computed tomographic images

OBJECTIVE

This study aimed to study the feasibility of measuring the arterial input function (AIF) in dynamic positron emission tomography (PET) studies using both PET and computed tomographic (CT) images.

MATERIAL AND METHODS

Eighteen newly diagnosed patients with head and neck cancer were recruited, and dynamic PET-CT scan was performed with contrast-enhanced CT. Phantom study with PET-CT scan was also performed for partial volume effect (PVE) correction. The PET-CT AIF was measured from both PET-CT images and corrected for PVE, together with the PET AIF, which was calculated from PET images. Both AIFs were used for calculating the net flux of [18F]fluoro-2-deoxy-D-glucose, Ki, and the correlation between these 2 sets of Ki was studied by Spearman correlation.

RESULTS

The PET-CT AIF was much larger than the PET AIF, whereas the Ki's by PET-CT AIF were much lower than the Ki's by PET AIF. However, the 2 sets of Ki were highly correlated (r = 0.969, P < 0.001).

CONCLUSIONS

It is feasible to measure AIF in PET-CT images without blood sampling. The PET-CT AIF is very different from the PET AIF calculated by PET images only without PVE correction. The PET-CT AIF may be a better choice because the Ki by PET AIF can be overestimated.

Accuracy of whole-body FDG-PET and FDG-PET/CT in M staging of nasopharyngeal carcinoma: a systematic review and meta-analysis

BACKGROUND

A meta-analysis was conducted to evaluate the accuracy of whole-body positron emission tomography (PET) or PET/CT in M staging of nasopharyngeal carcinoma (NPC).

METHODS

Through a search of relevant English language studies from October 1996 to September 2011, pooled estimated sensitivity, specificity, positive likelihood ratios, negative likelihood ratios, and summary receiver operating characteristic (SROC) curves of whole-body PET or PET/CT in M staging of NPC were calculated.

RESULTS

Three PET and 5 PET/CT studies were identified. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of FDG-PET or PET/CT were 0.83 (95% confidence interval [CI], 0.77-0.88), 0.97 (95% CI, 0.95-0.98), 23.38 (95% CI, 16.22-33.69), and 0.19 (95% CI, 0.13-0.25), respectively. The area under curve was 0.9764 and Q* index estimate was 0.9307 for FDG-PET or PET/CT.

CONCLUSION

Current evidence confirms the good diagnostic performance of the whole-body FDG-PET or PET/CT in M staging of NPC.

Oesophageal squamous cell carcinoma: relationship between fluorine-18 fludeoxyglucose positron emission tomography CT maximum standardised uptake value, metabolic tumour volume, and tumour, node and metastasis classification

OBJECTIVES

We aimed to evaluate the relationships between primary tumour, maximum standardised uptake value, metabolic tumour volume and seventh edition American Joint Committee on Cancer (AJCC) classification in oesophageal squamous cell carcinoma (OSCC) patients.

METHODS

Fluorine-18 fludeoxyglucose ((18)F-FDG) positron emission tomography (PET)-CT scans of 41 consecutive newly diagnosed OSCC patients were retrospectively reviewed. Maximum standard uptake value (SUV(max)) and metabolic tumour volume (MTV) were recorded. Two-tailed Spearman's correlation was used to analyse the relationships between the metabolic parameters and the AJCC staging system.

RESULTS

Positive correlations were observed between SUV(max), MTV and tumour (T) stage, in addition to node (N) stage and AJCC stage. Both metabolic parameters were independent variables that significantly affected the N stage and AJCC stage, and SUV(max) was the only independent variable that significantly affected the T stage.

CONCLUSION

The metabolic parameters derived from (18)F-FDG PET-CT were positively correlated with T, N and AJCC stage in primary OSCC. Our findings may suggest a complementary role of these parameters to seventh-edition AJCC staging in the prognostication of OSCC patients.

Prognostic significance of volume-based metabolic parameters in uterine cervical cancer determined using 18F-fluorodeoxyglucose positron emission tomography

OBJECTIVE

We compared the prognostic value of volume-based metabolic parameters determined using fluorine 18 (F) fluorodeoxyglucose (FDG) positron emission tomography (PET) (F-FDG PET) (with other prognostic parameters in uterine cervical cancer.

METHODS

The subjects were 73 female patients who had an initial diagnosis of uterine cervical cancer and who underwent F-FDG PET. Various metabolic or volume-based PET parameters including maximum and average standardized uptake values, metabolic tumor volume, and total lesion glycolysis (TLG) were measured in primary cervical tumors. Survival analysis for disease-free survival or progression-free survival was performed with a Kaplan-Meier method using PET parameters and other clinical variables. For determining independent prognostic factors, Cox regression analysis was performed.

RESULTS

Recurrence or disease progression occurred in 23 patients (31.5%). In univariate analysis, patient age (cutoff, 57 years, P < 0.05), International Federation of Gynecology and Obstetrics stage (P = 0.07), primary tumor size (cutoff, 6.7 cm; P < 0.05), lymph node status on PET (P < 0.005), treatment method (P < 0.01), metabolic tumor volume (cutoff, 82 cm; P = 0.001), and TLG (cutoff, 7600; P = 0.005) were significant predictors of recurrence or progression. In multivariate analysis, both lymph node status on PET (hazard ratio, 1.042 [negative vs intrapelvic metastasis only], 7.008 [negative vs extrapelvic metastasis]; P < 0.001) and TLG (cutoff, 7600; hazard ratio, 2.981; P < 0.05) were independent prognostic factors for predicting recurrence.

CONCLUSIONS

In uterine cervical cancer, TLG, a volume-based metabolic parameter, and lymph node status on PET may be significant independent prognostic factors for event-free survival.

Nasopharyngeal carcinoma: investigation of intratumoral heterogeneity with FDG PET/CT

OBJECTIVE

The purpose of this study was to quantitatively evaluate the role of intratumoral heterogeneity of (18)F-FDG uptake in characterizing nasopharyngeal carcinoma (NPC).

SUBJECTS AND METHODS

Forty consecutively registered patients with newly diagnosed NPC underwent PET/CT. The heterogeneity factor, defined as the derivative of a volume threshold function, was computed for each tumor. The relations between heterogeneity factor and maximum standardized uptake value (SUV(max)), tumor volume, and TNM category were determined by two-tailed Spearman correlation. Factors that potentially affect outcome determined by disease-free survival were studied by Kaplan-Meier analysis with a log-rank test for univariate analysis and the Cox proportional hazard model for multivariate analysis.

RESULTS

The heterogeneity factor ranged from -1.80 to -0.13 (mean, -0.40 [SD, 0.40]) and significantly correlated with SUV(max) (r = -0.372; p = 0.018), tumor volume (r = -0.983; p < 0.001), and T category (r = -0.457; p = 0.003) but not with N and M categories. There was a significant difference in heterogeneity factor between T1 and T2 tumors and T3 and T4 tumors (p = 0.012). The 2-year disease-free survival rate among the 38 patients was 67.4%. According to the results of Kaplan-Meier analysis with the log-rank test, heterogeneity factor and M category significantly affected disease-free survival. Patients with tumors that had a heterogeneity factor greater than -0.24 (less-heterogeneous group) (p = 0.0498) or M0 status (p < 0.001) had better disease-free survival rates. Multivariate analysis showed only M category to be an independent predictor of disease-free survival (p < 0.001).

CONCLUSION

The intratumoral heterogeneity of FDG uptake varies across NPC tumors, significantly correlates with tumor aggressiveness, and is predictive of patient outcome. These findings may be useful for characterizing NPC, predicting survival, and improving patient care.

Dynamic PET-CT studies for characterizing nasopharyngeal carcinoma metabolism: comparison of analytical methods

OBJECTIVES

To investigate the optimal PET protocol and analytical method to characterize the glucose metabolism in nasopharyngeal carcinoma (NPC).

METHODS

Newly diagnosed NPC patients were recruited and a dynamic PET-CT scan was performed. The optimized threshold to derive the arterial input function (AIF) was studied. Two-tissue compartmental kinetic modeling using three, four, and five parameters, Patlak graphical analysis, and time sensitivity (S-factor) analysis were performed. The best compartmental model was determined in terms of goodness of fit, and correlated with Ki from Patlak graphical analysis and the S-factor. The methods with R>0.9 and P<0.05 were considered acceptable. The protocols using two static scans with its retention index (RI=(SUV(2)/SUV(1)-1)×100%, where SUV is the standardized uptake value) were also studied and compared with S-factor analysis.

RESULTS

The best threshold of 0.6 was determined and used to derive AIF. The kinetic model with five parameters yields the best statistical results, but the model with k4=0 was used as the gold standard. All Ki values and some S-factors from data between various intervals (10-30, 10-45, 15-30, 15-45, 20-30, and 20-45 min) fulfilled the criteria. The RIs calculated from the S-factor were highly correlated to RI derived from simple two-point static scans at 10 and 30 min (R=0.9, P<0.0001).

CONCLUSION

The Patlak graphical analyses and even a 20-min-interval S-factor analysis or simple two-point static scans were shown to be sufficient to characterize NPC metabolism, confirming the clinical feasibility of applying a short dynamic with image-derived AIF or simple two-point static PET scans for studying NPC.

Experimental model of naturally occurring post-radiation sarcoma: interest of positron emission tomography (PET) for early detection

Radiotherapy is an integral part of overall cancer therapy. One of the most serious adverse effects of irradiation concern, for long-term survivors, the development of post-radiation sarcoma (PRS) in healthy tissues located within the irradiated area. PRS have bad prognosis and are often detected at a late stage. Therefore, it is obvious that the early detection PRS is a key-point and the development of preclinical models is worthy to evaluate innovative diagnostic and therapeutic procedures. The aim of this study was to develop a spontaneous rodent model of PRS and to evaluate the potency of Positron Emission Tomography (PET) for early detection. Fifteen Wistars rats were irradiated unilateraly on the hindlimb with a single dose of 30 Gy. Sequential analysis was based on observational staging recordings, Computerized Tomography (CT) scanning and PET. Tumors were removed and, histopathological and immunochemistry analyses were performed. Among the irradiated rats, 12 sarcomas (80%) were detected. All tumors occurred naturallty within the irradiated hindlimb and were highly aggressive since most tumors (75%) were successfully transplanted and maintained by serial transplantation into nude mice. Upon serial staging recordings, using PET, was found to enable the detection of PRS earlier after irradiation than with the other methods (i.e. 11.9 ± 1.8 vs 12.9 ± 2.6 months). These results confirmed the interest of experimental models of PRS for the preclinical evaluation of innovative diagnostic strategies and confirmed the potency of PET for early detection of PRS. This preclinical model of PRS can also be proposed for the evaluation of therapeutic strategies.

Prognostic impact of standardized uptake value of F-18 FDG PET/CT in nasopharyngeal carcinoma

PURPOSE

We evaluated the use of metabolic parameters of F-18 fluorodeoxyglucose positron emission tomography (FDG PET) for the assessment of the primary tumor and nodal metastasis in predicting survival in nasopharyngeal carcinoma (NPC) patients.

MATERIALS AND METHODS

The F-18 FDG PET/CT (computed tomography) scans of 46 consecutive newly diagnosed NPC patients were retrospectively reviewed. Maximal standardized uptake value (SUVmax) corrected for lean body mass of primary tumor (pSUVmax) and highest SUVmax of cervical lymph nodes (nSUVmax) were recorded. The association of FDG uptake and 2-year disease-free survival (DFS) was examined.

RESULTS

Significantly better DFS was found in patients with pSUVmax <7.5 and nSUVmax <6.5 (P = 0.042 and P = 0.019, respectively). In multivariate analysis, both pSUVmax and nSUVmax were significant independent predictors of DFS.

CONCLUSIONS

The SUVmax of the primary tumor and nodal metastasis are useful parameters for predicting DFS in NPC patients.