Positron emission tomography imaging in oncology

An evaluation of the physiological uptake range of 18F-fluoro-2-deoxy-D-glucose in normal ovaries of seven dogs using positron emission tomography/computed tomography

Introduction

This study evaluated the physiological uptake range of 18F-fluoro-2-deoxy-D-glucose (18F-FDG) in the normal ovaries of seven dogs using positron emission tomography/computed tomography (PET/CT).

Materials and methods

The dogs were subjected to general anesthesia and were positioned in ventral recumbency for PET/CT scans. The dosage of 18F-FDG ranged from 0.14 to 0.17 mCi/kg and was administered intravenously followed by 0.9% NaCl flushing; PET/CT images of each dog were obtained precisely 60 min after the injection of 18F-FDG. The regions of interest were drawn manually, and standardized uptake values (SUV) were calculated to evaluate the 18F-FDG uptake in each ovary. The maximum and mean SUVs (SUV max and SUV mean) for all the ovaries of the dogs were then computed.

Results

The range of SUV max and SUV mean of the normal ovaries of the dogs were 1.28-1.62 and 1.07-1.31 (mean ± standard deviation), respectively.

Conclusion

This is the first study to investigate the normal 18F-FDG uptake baseline data of normal canine ovaries using PET/CT scans. These data will help clinicians in identifying malignant tumors before anatomical changes in the ovary through PET/CT scans.

Imaging and biopsy of HIV-infected individuals undergoing analytic treatment interruption

Background

HIV persistence during antiretroviral therapy (ART) is the principal obstacle to cure. Lymphoid tissue is a compartment for HIV, but mechanisms of persistence during ART and viral rebound when ART is interrupted are inadequately understood. Metabolic activity in lymphoid tissue of patients on long-term ART is relatively low, and increases when ART is stopped. Increases in metabolic activity can be detected by ¹⁸F-fluorodeoxyglucose Positron Emission Tomography (FDG-PET) and may represent sites of HIV replication or immune activation in response to HIV replication.

Methods

FDG-PET imaging will be used to identify areas of high and low metabolic uptake in lymphoid tissue of individuals undergoing long-term ART. Baseline tissue samples will be collected. Participants will then be randomized 1:1 to continue or interrupt ART via analytic treatment interruption (ATI). Image-guided biopsy will be repeated 10 days after ATI initiation. After ART restart criteria are met, image-guided biopsy will be repeated once viral suppression is re-achieved. Participants who continued ART will have a second FDG-PET and biopsies 12–16 weeks after the first. Genetic characteristics of HIV populations in areas of high and low FDG uptake will be assesed. Optional assessments of non-lymphoid anatomic compartments may be performed to evaluate HIV populations in distinct anatomic compartments.

Anticipated results

We anticipate that PET standardized uptake values (SUV) will correlate with HIV viral RNA in biopsies of those regions and that lymph nodes with high SUV will have more viral RNA than those with low SUV within a patient. Individuals who undergo ATI are expected to have diverse viral populations upon viral rebound in lymphoid tissue. HIV populations in tissues may initially be phylogenetically diverse after ATI, with emergence of dominant viral species (clone) over time in plasma. Dominant viral species may represent the same HIV population seen before ATI.

Discussion

This study will allow us to explore utility of PET for identification of HIV infected cells and determine whether high FDG uptake respresents areas of HIV replication, immune activation or both. We will also characterize HIV infected cell populations in different anatomic locations. The protocol will represent a platform to investigate persistence and agents that may target HIV populations.

Study protocol registration

Identifier: NCT05419024.

Title: Advances of Gold Nanoclusters for Bioimaging

Gold nanoclusters (AuNCs) have become a promising material for bioimaging detection because of their tunable photoluminescence, large Stokes shift, low photobleaching, and good biocompatibility. Last decade, great efforts have been made to develop AuNCs for enhanced imaging contrast and multimodal imaging. Herein, an updated overview of recent advances in AuNCs was present for visible fluorescence (FL) imaging, near-infrared fluorescence (NIR-FL) imaging, two-photon near-infrared fluorescence (TP-NIR-FL) imaging, computed tomography (CT) imaging, positron emission tomography (PET) imaging, magnetic resonance imaging (MRI), and photoacoustic (PA) imaging. The justification of AuNCs applied in bioimaging mentioned above applications was discussed, the performance location of different AuNCs were summarized and highlighted in an unified parameter coordinate system of corresponding bioimaging, and the current challenges, research frontiers, and prospects of AuNCs in bioimaging were discussed. This review will bring new insights into the future development of AuNCs in bio-diagnostic imaging.

Prognostic Value of Volume-Based Parameters Measured by SSTR PET/CT in Neuroendocrine Tumors: A Systematic Review and Meta-Analysis

Purpose: A meta-analysis was conducted to investigate the value of the volume parameters based on somatostatin receptor (SSTR)-positron emission tomography (PET) in predicting the prognosis in patients with neuroendocrine tumors (NETs). Material: PUBMED, EMBASE, Cochrane library, and Web of Knowledge were searched from January 1990 to May 2021 for studies evaluating prognostic value of volume-based parameters of SSTR PET/CT in NETs. The terms used were "volume," "positron emission tomography," "neuroendocrine tumors," and "somatostatin receptor." Pooled hazard ratio (HR) values were calculated to assess the correlations between volumetric parameters, including total tumor volume (TTV) and total-lesion SSTR expression (TL-SSTR), with progression-free survival (PFS) and overall survival (OS). Heterogeneity and subgroup analysis were performed. Funnel plots, Begg's and Egger's test were used to assess possible underlying publication bias. Results: Eight eligible studies involving 593 patients were included in the meta-analysis. In TTV, the pooled HRs of its prognostic value of PFS and OS were 2.24 (95% CI: 1.73-2.89; P < 0.00001) and 3.54 (95% CI, 1.77-7.09; P = 0.0004), respectively. In TL-SSTR, the pooled HR of the predictive value was 1.61 (95% CI, 0.48-5.44, P = 0.44) for PFS. Conclusion: High TTV was associated with a worse prognosis for PFS and OS in with patients NETs. The TTV of SSTR PET is a potential objective prognosis predictor.

The role of FDG-PET-CT is limited in initial staging of nodal metastasis for thin cutaneous melanoma

INTRODUCTION

Positron emission tomography computed tomography (PET-CT) is often used to stage nodal metastases in thin cutaneous melanoma, with limited evidence.

METHODS

A retrospective review of patients with cutaneous malignant melanoma treated at our institution was performed from 2005 to 2015, identifying those who received a PET-CT prior to lymphadenectomy. Biopsy features, lymph node status, and PET-CT results were collected. We calculated the overall sensitivity, specificity, accuracy, likelihood ratios, and positive predictive value of PET-CT in identifying nodal metastases. Results were stratified by initial biopsy tumor depth.

RESULTS

We identified 367 cases; 95 obtained a PET-CT prior to lymphadenectomy. Overall, sensitivity and specificity of PET-CT was 34.6% and 95.4%, respectively. The positive likelihood ratio and negative likelihood ratio were 7.62 and 0.68, respectively. The accuracy was 78.2%. The positive predictive value for T3 and T4 melanomas were 100% and 81.4%, respectively. For thin melanomas, specificity and accuracy was 88.2% and 88.2%, respectively.

CONCLUSIONS

PET-CT has low specificity and its use alone is not recommended for initial staging of nodal metastases in thin cutaneous malignant melanoma.

Role of positron emission tomography/computed tomography in the evaluation of renal cell carcinoma

Introduction:

Positron emission tomography (PET) is not a standard recommendation in most of the major guidelines for the evaluation of renal cell carcinoma (RCC). Earlier studies evaluating PET scan in patients with RCC have provided discordant results. However, with the advent of newer hybrid PET/computed tomography (CT) scanning systems, this modality has shown increased efficacy in the evaluation of primary renal masses along with the detection of extrarenal metastases, restaging recurrent RCC, and also in monitoring response to targeted therapy. We performed a systematic review of the existing literature on the role of PET scan in the evaluation of RCC.

Methodology:

We systematically searched the databases of PubMed/Medline, Embase, and Google Scholar to identify studies on the use of PET scan in RCC. Using Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines, 94 full-text articles were selected, of which 54 relevant articles were then reviewed, after a consensus by the authors.

Results:

Several studies have shown similar sensitivity and specificity of fluoro-2-deoxy-2-d-glucose-PET (FDG-PET) scan as compared to conventional CT scan for the initial diagnosis of RCC, and an improved sensitivity and specificity for the detection of metastases and recurrences following curative therapy. The PET scan may also play a role in predicting the initial tumor biology and pathology and predicting the prognosis as well as the response to therapy.

Conclusion:

The current guidelines do not recommend PET scan in the staging armamentarium of RCCs. However, FDG-PET scan is as efficacious, if not better than conventional imaging alone, in the evaluation of the primary and metastatic RCC, as well as in evaluating the response to therapy, due to its ability to pick up areas of increased metabolic activity early on. Newer tracers such as ^Ga68 prostate specific membrane antigen-labeled ligands may help in opening up newer avenues of theragnostics.

Prognostic Implications of 18-FDG Positron Emission Tomography/Computed Tomography in Resectable Pancreatic Cancer

There are currently no known preoperative factors for determining the prognosis in pancreatic cancer. The aim of this study was to examine the role of 18-fluorodeoxyglucose (18-FDG) positron emission tomography/computed tomography (18-FDG-PET/CT) as a prognostic factor for patients with resectable pancreatic cancer. Data were obtained from a retrospective analysis of patients who had a preoperative PET scan and then underwent pancreatic resection from January 2007 to December 2015. The maximum standardized uptake value (SUVmax) of 18-FDG-PET/CT was calculated. Patients were divided into high (>3.65) and low (≤3.65) SUVmax groups, and compared in terms of their TNM classification (Union for International Cancer Contro classification), pathological grade, surgical treatment, state of resection margins, lymph node involvement, age, sex, diabetes and serum Carbohydrate Antigen 19-9 (CA 19-9) levels. The study involved 144 patients, 82 with high SUVmax pancreatic cancer and 62 with low SUVmax disease. The two groups’ disease-free and overall survival rates were significantly influenced by tumor stage, lymph node involvement, pathological grade, resection margins and SUVmax. Patients with an SUVmax ≤ 3.65 had a significantly better survival than those with SUVmax > 3.65 (p < 0.001). The same variables were independent predictors of survival on multivariate analysis. The SUVmax calculated with 18-FDG-PET/CT is an important prognostic factor for patients with pancreatic cancer, and may be useful in decisions concerning patients’ therapeutic management.

Differentiating Disease Flare From Infection: A Common Problem in Rheumatology. Do 18F-FDG PET/CT Scans and Novel Biomarkers Hold The Answer?

PURPOSE OF REVIEW

Fever is common within rheumatology but it is often challenging to identify its source. To do so correctly is paramount in patients with an underlying inflammatory condition receiving immunosuppressive therapy. This review article looks at the available evidence and merits of both 18F-fluoro-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) scans and new proposed biomarkers in determining the cause of fever within rheumatology.

RECENT FINDINGS

18F-FDG PET/CT scans are already an established tool in the detection and diagnosis of malignancy and are emerging for use in fever of unknown origin. More recently, they have been used to identify rheumatological causes of fever such as large vessel vasculitis and adult-onset Still's disease. Within these conditions, biomarkers such as procalcitonin and presepsin may help to differentiate endogenous from exogenous pyrogens. 18F-FDG PET/CT scanning shows promise in locating the source of pyrogens and may be superior to other conventional forms of imaging. As evidence and test availability increases, its use is likely to become commonplace in the diagnostic work-up of fever. Once a source is located, selected biomarkers may be used to confirm a cause.

Molecular Pathogenesis and Diagnostic Imaging of Metastatic Jaw Tumors

Metastasis is the spread of malignant cells from a primary tumor to distant sites through lymphatics or blood vessels. Malignant lesions metastasizing to the oral and perioral region are a rarity indeed. Malignant lesions could metastasize to both soft tissue of oral cavity and the hard tissues of the jaws and recent meta-analysis showed that metastasis is more common in the jaws than oral soft tissues because of rich vascular supply. The incidence is very low when compared to the incidence of primary oral cancers; nevertheless, one has to include in the diagnostic workup, metastatic malignant lesions, when an irregular ill-defined radiolucency or radiodensity with ragged edges in noted. It could be a challenging task for a diagnostician, in cases with the presence and location of the primary tumor is unknown. Advanced oral imaging technologies and biochemical markers play a vital role in diagnosing such lesions.

Tyrosine-Kinase Inhibitors Therapies with Mainly Anti-Angiogenic Activity in Advanced Renal Cell Carcinoma: Value of PET/CT in Response Evaluation

Renal cell carcinoma (RCC) is the most frequent renal tumor and the majority of patients are diagnosed with advanced disease. Tumor angiogenesis plays a crucial role in the development and progression of RCC together with hypoxia and glucose metabolism. These three pathways are strictly connected to the cell growth and proliferation, like a loop that is self-feeding. Over the last few years, the ever-deeper knowledge of its contribution in metastatic RCC led to the discovery of numerous tyrosine kinase inhibitors (TKIs) targeting pro-angiogenic receptors at different levels such as sunitinib, sorafenib, pazopanib, axitinib, tivozanib, and dovitinib. As anti-angiogenic agents, TKIs interfere the loop, being able to inhibit tumor proliferation. TKIs are now available treatments for advanced RCC, which demonstrated to improve overall survival and/or progression free survival. Their effects can be detectable early on Positron Emission Tomography/Computed Tomography (PET/CT) by change in ¹⁸F-fluoro-2-deoxy-2-d-glucose (¹⁸F-FDG) uptake, the main radiotracer used to date, as a strong indicator of biological response. ¹⁸F-FDG PET/CT demonstrated an ability to predict and monitor disease progression, allowing an early and reliable identification of responders, and could be used for image-guided optimization and "personalization" of anti-angiogenic regimens. New radiotracers for biometabolic imaging are currently under investigation, which exploit the other pathways involved in the cancer process, including cellular proliferation, aerobic metabolism, cell membrane synthesis, hypoxia and amino acid transport, as well as the angiogenic process, but they require further studies.

18F-FDG PET/CT Volumetric Parameters are Associated with Tumor Grade and Metastasis in Pancreatic Neuroendocrine Tumors in von Hippel-Lindau Disease

BACKGROUND

Approximately 8-17 % of patients with von Hippel-Lindau (VHL) syndrome develop pancreatic neuroendocrine tumors (PNETs), with 11-20 % developing metastases. Tumor grade is predictive of prognosis.

OBJECTIVE

The aim of this study was to determine if preoperative metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were associated with metastatic disease and tumor grade.

METHODS

Sixty-two patients with VHL-associated PNETs prospectively underwent ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT). MTV, TLG, and maximum standardized uptake value (SUV_max) were measured using a semi-automatic method. Surgically resected PNETs were classified according to 2010 World Health Organization tumor grade classification. MTV, TLG, and SUV_max were analyzed by metastatic disease and tumor grade using the Mann-Whitney test.

RESULTS

A total of 88 PNETs were identified by CT and ¹⁸F-FDG PET/CT, 10 of which were non-FDG-avid. Histologic grading was available for 20 surgical patients. Patients with metastatic PNETs had a higher TLG (median 25.9 vs. 7.7 mean SUV [SUV_mean]*mL; p = 0.0092) compared with patients without metastasis, while patients with grade 2 PNETs had a higher MTV (median 6.9 vs. 2.6 mL; p = 0.034) and TLG (median 41.2 vs. 13.1 SUV_mean*mL; p = 0.0035) compared with patients with grade 1 PNETs. No difference in tumor size or SUV_max was observed between the groups.

CONCLUSIONS

Patients with metastatic PNETs have a higher TLG compared with patients without metastasis. Grade 2 PNETs have a higher MTV and TLG compared with grade 1 PNETs. Tumor size and SUV_max were not associated with grade. Volumetric parameters on ¹⁸F-FDG PET/CT may be useful in detecting higher grade PNETs with a higher malignant potential that may need surgical intervention.

The Place of FDG PET/CT in Renal Cell Carcinoma: Value and Limitations

Unlike for most other malignancies, application of FDG PET/CT is limited for renal cell carcinoma (RCC), mainly due to physiological excretion of 18F-fluoro-2-deoxy-2-d-glucose (FDG) from the kidneys, which decreases contrast between renal lesions and normal tissue, and may obscure or mask the lesions of the kidneys. Published clinical observations were discordant regarding the role of FDG PET/CT in diagnosing and staging RCC, and FDG PET/CT is not recommended for this purpose based on current national and international guidelines. However, quantitative FDG PET/CT imaging may facilitate the prediction of the degree of tumor differentiation and allows for prognosis of the disease. FDG PET/CT has potency as an imaging biomarker to provide useful information about patient’s survival. FDG PET/CT can be effectively used for postoperative surveillance and restaging with high sensitivity, specificity, and accuracy, as early diagnosis of recurrent/metastatic disease can drastically affect therapeutic decision and alter outcome of patients. FDG uptake is helpful for differentiating benign or bland emboli from tumor thrombosis in RCC patients. FDG PET/CT also has higher sensitivity and accuracy when compared with bone scan to detect RCC metastasis to the bone. FDG PET/CT can play a strong clinical role in the management of recurrent and metastatic RCC. In monitoring the efficacy of new target therapy such as tyrosine kinase inhibitors (TKIs) treatment for advanced RCC, FDG PET/CT has been increasingly used to assess the therapeutic efficacy, and change in FDG uptake is a strong indicator of biological response to TKI.

Lesion Detectability and Clinical Effectiveness of Dual-head Coincidence Gamma Camera Imaging in Comparison with Dedicated PET Systems in Tumour Patients

The lesion detection capability and clinical effectiveness of dual-head coincidence gamma camera imaging (c-PET) were compared with those of dedicated positron emission tomography (d-PET) in 37 cancer patients who underwent whole-body c-PET and d-PET imaging after administration of 370 − 540 MBq 18F-fluorodeoxyglucose. Eighty-nine lesions were detected on c-PET whereas 133 lesions were seen with d-PET imaging. The relative sensitivity of c-PET compared with d-PET was 62% and 73% for lesions < 15 and ≤ 15 mm, respectively, and the relative concordance rate was 84% when the patients were restaged. Since the lesion detection rate of c-PET imaging was lower than that of d-PET, the detection of small lesions, therefore, requires care. The clinical effectiveness of c-PET, however, was similar to that of d-PET and, therefore, it is concluded that c-PET can be used as an alternative to d-PET, particularly considering the high cost and limited availability of d-PET cameras.

Prognostic Value of SUVmax Measured by Pretreatment Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Patients with Ewing Sarcoma

Aim

The aim of this retrospective study was to determine whether glucose metabolism assessed by using Fluorine-18 (F-18) fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) provides prognostic information independent of established prognostic factors in patients with Ewing sarcoma.

Methods

We retrospectively reviewed the medical records of 34 patients (men, 19; women, 15; mean age, 14.5 ± 9.7 years) with pathologically proven Ewing sarcoma. They had undergone F-18 FDG PET/CT as part of a pretreatment workup between September 2006 and April 2012. In this analysis, patients were classified by age, sex, initial location, size, and maximum standardized uptake value (SUVmax). The relationship between FDG uptake and survival was analyzed using the Kaplan-Meier method with the log-rank test and Cox’s proportional hazards regression model.

Results

The median survival time for all 34 subjects was 999 days and the median SUV by using PET/CT was 5.8 (range, 2–18.1). Patients with a SUVmax ≤ 5.8 survived significantly longer than those with a SUVmax > 5.8 (median survival time, 1265 vs. 656 days; p = 0.002). Survival was also found to be significantly related to age (p = 0.024), size (p = 0.03), and initial tumor location (p = 0.036). Multivariate analysis revealed that a higher SUVmax (p = 0.003; confidence interval [CI], 3.63–508.26; hazard ratio [HR], 42.98), older age (p = 0.023; CI, 1.34–54.80; HR, 8.59), and higher stage (p = 0.03; CI, 1.21–43.95; HR, 7.3) were associated with worse overall survival.

Conclusions

SUVmax measured by pretreatment F-18-FDG PET/CT can predict overall survival in patients with Ewing sarcoma.

[Synopsis on clinical practice guideline of gastric cancer in Korea: an evidence-based approach]

Although, gastric cancer is quite common in Korea, the treatment outcome is relatively favorable compared to that of Western countries. However, there is no Korean multidisciplinary guideline for gastric cancer and thus, a guideline adequate for domestic circumstances is required. Experts from related societies developed 22 recommendation statements for the diagnosis (n=9) and treatment (n=13) based on relevant key questions. Evidence levels based on systematic review of literatures were classified as five levels from A to E, and recommendation grades were classified as either strong or weak. The topics of this guideline cover diagnostic modalities (endoscopy, endoscopic ultrasound, radiologic diagnosis), treatment modalities (surgery, therapeutic endoscopy, chemotherapy, radiotherapy) and pathologic evaluation. External review of the guideline was conducted at the finalization phase.

Clinical practice guidelines for gastric cancer in Korea: an evidence-based approach

Although gastric cancer is quite common in Korea, the treatment outcome is relatively favorable compared to those in western countries. However, there are currently no Korean multidisciplinary guidelines for gastric cancer. Experts from related societies developed guidelines de novo to meet Korean circumstances and requirements, including 23 recommendation statements for diagnosis (n=9) and treatment (n=14) based on relevant key questions. The quality of the evidence was rated according to the GRADE evidence evaluation framework: the evidence levels were based on a systematic review of the literature, and the recommendation grades were classified as either strong or weak. The applicability of the guidelines was considered to meet patients' view and preferences in the context of Korea. The topics of the guidelines cover diagnostic modalities (endoscopy, endoscopic ultrasound, and radiologic diagnosis), treatment modalities (surgery, therapeutic endoscopy, chemotherapy, and radiotherapy), and pathologic evaluation. An external review of the guidelines was conducted during the finalization phase.

Predictive value of maximum standardized uptake value (SUVmax) on 18F-FDG PET/CT in patients with locally advanced or metastatic pancreatic cancer

PURPOSE

We investigated the prognostic role of 18F-FDG PET/CT in the prediction of progression-free survival (PFS) and chemotherapeutic response in patients with locally advanced or metastatic pancreatic cancer.

METHODS

We enrolled 21 newly diagnosed patients with locally advanced or metastatic pancreatic cancer who underwent 18F-FDG PET/CT scanning before palliative gemcitabine-based chemotherapy between 2006 and 2012. Maximum standardized uptake value (SUVmax) of the primary tumor was measured by 18F-FDG PET/CT. Chemotherapeutic response was evaluated according to the Response Evaluation Criteria in Solid Tumors. Survival analysis was performed for time to progression using the Kaplan-Meier method. Cox proportional hazard models were used to determine independent prognostic factors.

RESULTS

All pancreatic tumors showed detectable FDG uptake (mean SUVmax = 6.8 ± 3.0, range 2-12) The mean SUVmax values among response groups showed no significant difference (P = 0.853) and chemotherapeutic response was not different according to SUVmax level (P = 0.807). PFS was significantly shorter in the high SUVmax (≥6.8) group than in the low SUVmax (<6.8) group (2.9 vs. 6 months, P = 0.012). Multivariate analysis revealed that SUVmax was an independent prognostic factor for predicting PFS (P = 0.046).

CONCLUSIONS

Higher SUVmax of primary pancreatic tumor is associated with poor PFS and pretreatment SUVmax is an independent prognostic factor for predicting PFS in patients with locally advanced or metastatic pancreatic cancer who received gemcitabine-based palliative chemotherapy. However, pretreatment SUVmax is not associated with chemotherapeutic response.

Prognostic Value of Volume-Based Metabolic Parameters Measured by (18)F-FDG PET/CT of Pancreatic Neuroendocrine Tumors

PURPOSE

To date, the prognostic value of (18)F-FDG PET/CT for patients with pancreatic neuroendocrine tumors (PNETs) has not been well characterized. We investigated the prognostic value of volumetric parameters using (18)F-FDG PET/CT in this patient population.

METHODS

We retrospectively reviewed 20 cases of pathologically proven PNET in patients who had undergone pre-therapeutic (18)F-FDG PET/CT. PET parameters including maximum and average standardized uptake values (SUVmax, SUVave), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the primary tumor were measured using a threshold SUV to determine the boundaries of the tumors. Univariate and multivariate survival analyses were performed with adjustments for PET parameters and other clinical values.

RESULTS

The median clinical follow-up was 22.3 (range, 1.2-95.4) months. Cancer-related death occurred in 5 of 20 patients (25 %). Patients had clinical or pathological stages of I in seven patients, II in six patients, III in three patient, and IV in four patients. According to the WHO histological classification of subtypes, 3 patients exhibited well-differentiated PNETs, 13 patients had well-differentiated endocrine carcinomas, and 4 had poorly differentiatedendocrine carcinomas. Univariate analysis showed that tumor size (p = 0.028), AJCC stage (p = 0.009), T stage (p = 0.028), M stage (p = 0.029), treatment modality (p = 0.045), MTV (p = 0.003) and TLG (p = 0.027) were significant predictors of overall survival. On multivariate analysis, MTV (HR = 10.859, p = 0.031) was a significant independent predictor of overall survival along with the AJCC stage (HR = 11.556, p = 0.027).

CONCLUSION

In patients with PNETs, the MTV of the primary tumor as measured by (18)F-FDG PET/CT along with the AJCC stage may be a significant independent prognostic factor for overall survival.

PET or PET/CT for detection of peritoneal carcinomatosis: a meta-analysis

The present study assessed the diagnostic performances of (18)F-FDG PET or PET/CT in detecting peritoneal carcinomatosis in patients with cancer.

METHODS

Through a search of MEDLINE (January 1998 to September 2012), an overall weighted average for sensitivity and specificity was calculated using the weighted averages of the sample sizes in each relevant study. Pooled estimates of positive and negative likelihood ratios were calculated using fixed and random effects models, respectively, according to the heterogeneity among studies. A summary receiver operating characteristics (sROC) curve was constructed and the area under the sROC curve (AUC) was calculated. To explore heterogeneity, due to sources other than threshold effects, I-square was calculated.

RESULTS

The present study included analyses of patients (n = 513) from 7 studies. Results indicated a significant heterogeneity for sensitivity and specificity (I(2) > 50% and P < 0.05). The overall pooled estimates for sensitivity and specificity of FDG PET or PET/CT scans in the detection of peritoneal carcinomatosis were 72.4% (95% CI, 64.4%-79.5%) and 96.7% (95% CI, 94.4%-98.3%), respectively. The positive likelihood ratio was 10.414 (95% CI, 6.195-17.506) and the negative likelihood ratio 0.312 (95% CI, 0.159-0.612). The AUC was 0.9404. The overall diagnostic accuracy (Q* index) was 87.8%.

CONCLUSION

The high specificity may provide the reliability of a positive FDG PET or PET/CT to detect peritoneal carcinomatosis in patients with cancer. FDG PET or PET/CT has only weak power to exclude the presence of peritoneal carcinomatosis. By a good overall diagnostic accuracy, FDG PET or PET/CT may prove beneficial to surgeons when selecting appropriate patients on whom to perform laparoscopy or laparotomy.

Role of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography in predicting the pathologic response to preoperative chemoradiation therapy in patients with resectable T3 pancreatic cancer

BACKGROUND

The purpose of this study was to evaluate whether (18)F-fluorodeoxyglucose positron emission tomography in combination with computed tomography (FDG-PET/CT) could correctly predict the pathologic response to preoperative chemoradiation therapy (CRT) for resectable pancreatic cancer.

METHODS

Each of the 40 patients underwent FDG-PET/CT before and after preoperative CRT. The maximum standard uptake value (SUV) was measured for the primary tumor before and after preoperative CRT, defined as pre-CRT SUV and post-CRT SUV, respectively. The proportional alteration of the SUV decline (regression index) between post-CRT SUV and pre-CRT SUV was also calculated. These three indicators were associated with the pathologic response.

RESULTS

Patients were classified as 21 responders and 19 nonresponders according to the histologic features. A pre-CRT SUV ≥ 4.7 was seen in 15 (71 %) of 21 responders and in 6 (32 %) of 19 nonresponders (p = 0.03). A regression index ≥ 0.46 was seen in 15 (71 %) responders and 5 (26 %) nonresponders (p = 0.01).

CONCLUSIONS

A better pathological response can be expected for pancreatic cancer patients who have a high regression index (≥ 0.46) and a high pre-CRT SUV (≥ 4.7). The SUV measurement using FDG-PET/CT is a useful tool for predicting the pathologic response to preoperative CRT.

Prognostic value of SUVmax measured by Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography with Computed Tomography in Patients with Pancreatic Cancer

PURPOSE

Recent studies have been conducted on the relationship between fluorodeoxyglucose (FDG) uptake in F-18 FDG PET/CT and prognosis in patients with pancreatic cancer, but these studies have been carried out in small numbers of patients. The aim of this retrospective study was to determine in a large number of patients whether glucose metabolism as assessed by F-18 FDG PET/CT provides prognostic information independent of established prognostic factors in patients with pancreatic cancer.

METHODS

We reviewed retrospectively the medical records of 165 patients (men 105, women 60, mean age 67 ± 10 years) with a diagnosis of pancreatic cancer that had undergone F-18 FDG PET/CT as part of a pretreatment workup from January 2004 to December 2009. Subsequently, all patients underwent surgery, cyberknife, radiotherapy, and/or chemotherapy. For the analysis, patients were classified by age, demographic data, maximum standardized uptake value (SUVmax), size, location, serum level of CA19-9, type of treatment, and AJCC stage. The relationship between FDG uptake and survival was analyzed using the Kaplan-Meier with log-Rank test and Cox's proportional-hazard regression methods.

RESULTS

Median survival for all 165 study subjects was 290 days and median SUV by PET/CT was 5.8 (range: 0-25.1). Patients were allocated to high (> 4.1) and low (≤4.1) SUV groups, and median survivals of these patients were 229 days and 610 days, respectively, which were significantly different (p < 0.0001). Furthermore, SUVmax was found to be significantly related to survival in each stage, i.e., there were 1267 days in stage I, 440 days in stage II, 299 days in stage III, and 143 days in stage IV (p < 0.0001). The median survival was also found to be significantly related to tumor size (p = 0.001), site (p = 0.0298), serum level of CA19-9 (p = 0.0017), distant metastasis (p < 0.0001), and type of treatment (p < 0.0001). Multivariate analysis study revealed that the patients with a low SUV (p = 0.0298), a lower serum level of CA19-9 (p = 0.0071), a lower stage (p = 0.0017), and no distant metastasis (p < 0.0001) had longer survivals. In addition, SUVmax values were found to have a similar hazard ratio of distant metastasis; it was well known predictor. Furthermore, SUVmax values showed a higher hazard ratio than that of other clinicopathologic predictors.

CONCLUSION

The present study shows that SUVmax on F-18 FDG PET/CT can provide a prognostic information in patients with pancreatic cancer.

Patients with non-[18 F]fludeoxyglucose-avid advanced hepatocellular carcinoma on clinical staging may achieve long-term recurrence-free survival after liver transplantation

There is increasing evidence that a relevant number of patients with hepatocellular carcinoma (HCC) exceeding the Milan criteria may benefit from liver transplantation (LT). We retrospectively analyzed the prognostic significance of [(18) F]fludeoxyglucose ([(18) F]FDG) positron emission tomography (PET) for identifying appropriate LT candidates with advanced HCC on clinical staging. Between 1995 and 2008, 111 patients with HCC were listed for LT. All underwent a pretransplant PET evaluation. LT was performed for 91 of these patients. The tumor recurrence rate after LT was 3.6% for patients with non-[(18) F]FDG-avid (PET(-) ) tumors, but it was 54.3% for patients with [(18) F]FDG-avid (PET(+) ) tumors (P < 0.001). The 5-year recurrence-free survival rates were comparable for patients with tumors meeting the Milan criteria (86.2%) and patients with PET(-) HCC exceeding the Milan criteria (81%) at LT, but these rates were significantly higher than the rate for liver recipients with [(18) F]FDG-avid advanced HCC (21%, P = 0.002). In a multivariate analysis, negative PET findings (odds ratio = 21.6, P < 0.001), an alpha-fetoprotein level <400 IU/mL (odds ratio = 3.3, P = 0.013), and a total tumor diameter <10 cm (odds ratio = 3.0, P = 0.022) were identified as pretransplant prognostic variables for recurrence-free survival. A PET(+) status was assessed as the only independent clinical predictor of tumor-related patient dropout from the waiting list (hazard ratio = 5.7, P = 0.01). Patients with non-[(18) F]FDG-avid HCC beyond the Milan criteria according to clinical staging may achieve excellent long-term recurrence-free survival after LT.

[Case of temporal arteritis: FDP-PET ((18)F-fluorodeoxyglucose-positron emission tomography) was useful for early diagnosis and treatment]

A 61-year-old woman with a continuous left temporal headache and a fever of 39°C for about one month was admitted to our hospital. The physical examination was not remarkable, except for slight tenderness of the left temporal side of her head. Laboratory data on admission revealed an increase of leucocytes (9,700/µl), blood platelets (59.4×10(4)/µl), and serum c-reactive protein (CRP) (10.9 mg/dl). The erythrocyte sedimentation rate (ESR) was also elevated (88 mm/1 h). After gallium scintigraphy, a gallium-67 uptake was weakly detected at the left temporal side of her head. However, after FDG-PET examination, a high FDG uptake was detected in her temporal artery, abdominal aorta, and bilateral femoral arteries. Moreover, Doppler sonography showed a hypoechoic halo around her left temporal artery. After treatment with oral prednisolone (40 mg/day), her headache disappeared and her serum CRP level returned to normal. Finally, the patient had pathological temporal arteritis proven by a biopsy. It is difficult to make an early diagnosis of temporal arteritis if the dilatation or swelling of the temporal arteries is not present. FDG-PET is considered a useful examination not only for the exploration of tumors, but also for the evaluation of the inflammation of large vessels.

Diagnosis of peritoneal dissemination: comparison of 18F-FDG PET/CT, diffusion-weighted MRI, and contrast-enhanced MDCT

OBJECTIVE

The purpose of this study was to compare the diagnostic performance of (18)F-FDG PET/CT, MRI with and without diffusion-weighted imaging (DWI), and contrast-enhanced MDCT in the detection of peritoneal dissemination of malignant tumors.

MATERIALS AND METHODS

We retrospectively evaluated the cases of 107 patients who underwent PET/CT and 130 patients who underwent MRI and contrast-enhanced MDCT. Twenty-six patients who underwent PET/CT and 23 who underwent MRI and contrast-enhanced MDCT were found to have peritoneal dissemination. All images were independently evaluated by two radiologists using a 5-point grading system. The results of PET/CT, T1- and T2-weighted MRI without DWI, MRI with DWI (b = 1,000 s/mm(2)), and contrast-enhanced MDCT were compared patient by patient and lesion by lesion by use of receiver operating characteristics analysis. Sensitivity, specificity, and positive predictive value were calculated and compared by use of the chi-square test.

RESULTS

Patient by patient, the area under the receiver operating characteristics curve of MRI without DWI (0.88) was significantly less than that of the other modalities (contrast-enhanced MDCT, 0.91; MRI with DWI, 0.93; PET/CT, 0.97). The sensitivity of PET/CT (94%) was significantly higher than that of MRI without DWI (70%). The specificities of the modalities were not significantly different. In lesion-by-lesion analysis, MRI without DWI had significantly lower sensitivity (56%) than the other modalities (contrast-enhanced MDCT, 76%; MRI with DWI, 84%; PET/CT, 89%). The positive predictive value of PET/CT (93%) was significantly higher than that of the other three modalities (contrast-enhanced MDCT, 73%; MRI without DWI, 70%; MRI with DWI, 72%).

CONCLUSION

PET/CT is the most useful technique for pathologic staging in the care of patients with malignant disease. If PET/CT is not available, DWI can be used as a screening tool.

Physiology and pathophysiology of incidental findings detected on FDG-PET scintigraphy

A routine feature of positron emission tomography/computed tomography (PET/CT) imaging is whole-body acquisition that results in many unexpected findings identified outside of the primary region of abnormality. Furthermore, (18)F-fluorodeoxyglucose (FDG) is a marker of glycolysis and does not specifically accumulate in malignancy. Understanding the physiology and pathophysiology of normal FDG distribution and common incidental findings is therefore essential to the physician interpreting whole-body FDG-PET/CT studies. Whereas many incidental findings are benign and of limited clinical significance, others represent uncommon manifestations of the primary malignancy, second malignancies, or various clinically significant pathologic processes. Patients with a single malignancy are at greater risk of developing synchronous or metachronous second malignancies, possibly related to exposure to shared carcinogenic agents or presence of prooncogenic mutations. The decision of how to pursue an intervention on the basis of an incidental finding is generally left to clinical judgment.

Prognostic value of (18)F-fluorodeoxyglucose positron emission tomography in patients with extrahepatic bile duct cancer

BACKGROUND

(18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) is used in the differential diagnosis and staging of extrahepatic bile duct cancer (EBDC), but its prognostic value has not been fully elucidated. In this study, we investigated the prognostic value of FDG-PET in EBDC patients.

METHODS

The study included 73 consecutive patients with EBDC, of whom 48 underwent surgical resection for EBDC. The effects of clinicopathological factors including the standardized uptake value (SUV) of the primary lesion and lymph node metastasis detected by FDG-PET (PET-N) on overall survival were evaluated.

RESULTS

In all 73 patients, multivariate analysis showed that surgical resection (risk ratio 2.5, 95% confidence interval [CI] 1.17-5.35, P = 0.018) and the SUV (2.0, 1.07-3.91, P = 0.030) were independent predictors of survival. In the 48 patients who underwent surgical resection, multivariate analysis revealed that perineural invasion (risk ratio 3.2, 95% CI 1.28-7.93, P = 0.012), pathologic lymph node metastasis (3.4, 1.27-9.17, P = 0.015), and PET-N (4.0, 1.10-15.25, P = 0.036) were independent predictors of overall survival. In the 25 patients without surgical resection, the SUV showed a significant relationship with overall survival (P = 0.014).

CONCLUSION

Our data suggest that the SUV of the primary lesion is a useful prognostic factor in patients with EBDC, and the prognosis for patients with PET-N remains very poor despite surgical resection.

Recurrence-free long-term survival after liver transplantation in patients with 18F-FDG non-avid hilar cholangiocarcinoma on PET

The aim of this retrospective study was to assess the value of (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) for predicting biological tumor behavior and outcome after liver transplantation (LT) in patients with otherwise unresectable hilar cholangiocarcinoma (HC). Preoperative (18)F-FDG-PET scanning was performed in 13 patients with type IV Klatskin tumor before LT. PET+ status indicated patients with an increased pretransplant (18)F-FDG uptake, whereas PET- recipients had no increased preoperative (18)F-FDG uptake on PET. Pretransplant PET findings were correlated with histopathological tumor characteristics and patient outcome after LT. Eight patients demonstrated positive preoperative PET findings (61.5%), whereas five patients had no increased preoperative (18)F-FDG tumor uptake (38.5%) on PET. One PET+ patient died after 1 month due to liver allograft dysfunction. Seven PET+ liver recipients developed tumor recurrence, whereas five PET- patients were tumor-free alive after a median of 76 months post-LT (p = 0.001). The 2-year recurrence-free survival rate after LT was 100% in PET- patients and 28.6% in the PET+ population (log-rank = 0.008). Our results suggest that patients with (18)F-FDG non-avid HC on PET may achieve recurrence-free long-term survival after LT.

Clinical Applications of FDG PET and PET/CT in Head and Neck Cancer

18F-FDG PET plays an increasing role in diagnosis and management planning of head and neck cancer. Hybrid PET/CT has promoted the field of molecular imaging in head and neck cancer. This modality is particular relevant in the head and neck region, given the complex anatomy and variable physiologic FDG uptake patterns. The vast majority of 18F-FDG PET and PET/CT applications in head and neck cancer related to head and neck squamous cell carcinoma. Clinical applications of 18F-FDG PET and PET/CT in head and neck cancer include diagnosis of distant metastases, identification of synchronous 2nd primaries, detection of carcinoma of unknown primary and detection of residual or recurrent disease. Emerging applications are precise delineation of the tumor volume for radiation treatment planning, monitoring treatment, and providing prognostic information. The clinical role of 18F-FDG PET/CT in N0 disease is limited which is in line with findings of other imaging modalities. MRI is usually used for T staging with an intense discussion concerning the preferable imaging modality for regional lymph node staging as PET/CT, MRI, and multi-slice spiral CT are all improving rapidly. Is this review, we summarize recent literature on 18F-FDG PET and PET/CT imaging of head and neck cancer.

Clinical practice guidance for radiotherapy planning after induction chemotherapy in locoregionally advanced head-and-neck cancer

PURPOSE

The use of induction chemotherapy (IC) for locoregionally advanced head-and-neck cancer is increasing. The response to IC often causes significant alterations in tumor volume and location and shifts in normal anatomy. Proper determination of the radiotherapy (RT) targets after IC becomes challenging, especially with the use of conformal and precision RT techniques. Therefore, a consensus conference was convened to discuss issues related to RT planning and coordination of care for patients receiving IC.

METHODS AND MATERIALS

Ten participants with special expertise in the various aspects of integration of IC and RT for the treatment of locoregionally advanced head-and-neck cancer, including radiation oncologists, medical oncologists, and a medical physicist, participated. The individual members were assigned topics for focused, didactic presentations. Discussion was encouraged after each presentation, and recommendations were formulated.

RESULTS

Recommendations and guidelines emerged that emphasize up-front evaluation by all members of the head-and-neck management team, high-quality baseline and postinduction planning scans with the patient in the treatment position, the use of preinduction target volumes, and the use of full-dose RT, even in the face of a complete response.

CONCLUSION

A multidisciplinary approach is strongly encouraged. Although these recommendations were provided primarily for patients treated with IC, many of these same principles apply to concurrent chemoradiotherapy without IC. A rapid response during RT is quite common, requiring the development of two or more plans in a sizeable fraction of patients, and suggesting the need for similar guidance in the rapidly evolving area of adaptive RT.

18F-FDG-uptake of hepatocellular carcinoma on PET predicts microvascular tumor invasion in liver transplant patients

Vascular invasion of hepatocellular carcinoma (HCC) is a major risk factor for poor outcome after liver transplantation (LT). The aim of this retrospective analysis was to assess the value of preoperative positron emission tomography (PET) using (18)F-fluorodeoxyglucose ((18)F-FDG) in liver transplant candidates with HCC for predicting microvascular tumor invasion (MVI) and posttransplant tumor recurrence. Forty-two patients underwent LT for HCC after PET evaluation. Sixteen patients had an increased (18)F-FDG tumor uptake on preoperative PET scans (PET +), while 26 recipients revealed negative PET findings (PET-) pre-LT. PET- recipients demonstrated a significantly better 3-year recurrence-free survival (93%) than PET + patients (35%, p < 0.001). HCC recurrence rate was 50% in the PET + group, and 3.8% in the PET-population (p < 0.001). PET + status was identified as independent predictor of MVI [hazard ratio: 13.4]. Patients with advanced PET negative tumors and patients with HCC meeting the Milan criteria had a comparable 3-year-recurrence-free survival (80% vs. 94%, p = 0.6). Increased (18)F-FDG uptake on PET is predictive for MVI and tumor recurrence after LT for HCC. Its application may identify eligible liver transplant candidates with tumors beyond the Milan criteria.

Activity-based costing evaluation of [18F]-fludeoxyglucose production

INTRODUCTION

As healthcare expenses are escalating in many countries, the sector faces a new challenge of becoming more cost efficient. There is an urgent need for more accurate data on the costs of healthcare procedures. The cost of Positron Emission Tomography (PET) with [(18)F]-fludeoxyglucose ((18)F-FDG) studies is mainly influenced by the price of the radiopharmaceutical, which may vary throughout Europe from 300 to 500 Euro per patient dose (370 MBq). The aim of the current study is to conduct an activity-based costing (ABC) estimation of (18)F-FDG production in Europe to better identify the different cost components and to analyse their relative contribution to the total cost.

MATERIALS AND METHODS

Financial data were collected on capital expense and global operating costs through interviews with industry experts, PET centre managers, evaluation of prior studies, and review of expenses incurred at the University Medical Centre in Groningen (The Netherlands). After mapping the activities, we divided the cost in five categories: wage, equipment, consumables, overhead and space costs. A sensitivity analysis was performed for key cost components, including the compliance with regulatory requirements.

RESULTS

The critical factor for profitability was throughput. Including the European regulation procedure, the cost for 370 MBq (18)F-FDG patient dose, 3 h EOS without delivery cost, ranges between 155 and 177 Euro/dose for two production runs and between 210 and 237 Euro/dose for one production run. These costs are predominantly determined by personnel and equipment costs, although the cost for quality assurance increases steadily.

CONCLUSION

The ABC analysis provides significant insight into the production cost components of (18)F-FDG through different operating configurations. Reductions in equipment prices, increased availability of radiopharmaceuticals, growth in demand, and improvements in reimbursement will all contribute to the financial viability of this imaging technique.

Ovarian cancer

Imaging has become an essential part of the clinical management of patients with ovarian cancer, contributing to tumor detection, characterization, staging, treatment planning, and follow-up. Imaging findings incorporated into the clinical impression assist in creating a treatment plan specific for an individual patient. Advances in cross-sectional imaging and nuclear medicine (PET) have yielded new insights into the evaluation of tumor prognostic factors. A multimodality approach can satisfy the complex imaging needs of a patient with ovarian cancer; however, the success of such an approach always depends on available resources and on the skills of the physicians involved.

Preoperative positron emission tomography with fluorine-18-fluorodeoxyglucose is predictive of prognosis in patients with hepatocellular carcinoma after resection

BACKGROUND

Hepatocellular carcinomas (HCCs) accumulate fluorine-18 fluorodeoxyglucose (FDG) to various degrees. The standardized uptake values (SUVs) of FDG-positron emission tomography (PET) in high-grade HCCs are significantly higher than those in low-grade HCCs.

AIM

The aim of this study was to evaluate the possible usefulness of FDG-PET in predicting the prognosis of HCC patients after resection. We analyzed the relationship between the tumor to non-tumor SUV ratios (SUV ratio) and surgical outcome in 31 patients.

RESULTS

Of the 31 cases of HCC studied, seven (23%) exhibited SUV ratios greater than 2, as the cutoff value. The percentage of patients with poorly differentiated HCC was greater in the higher SUV ratio group (SUV ratio >2) than in the lower SUV ratio group (SUV ratio <2) (57 vs. 32%). The overall survival was significantly longer in the lower SUV ratio group than in the higher SUV ratio group (5-year-survival rate: 63 vs. 29% P = 0.006) (median survival time: 2310 vs.182 days).

CONCLUSION

The SUV ratio was related significantly to disease-related death as well as other predictive factors, including the number of tumors, the size, stage, and involvement of vessels, and the involvement of the capsule. Consequently, we conclude that the SUV ratio provides information of prognostic relevance in patients with HCC before surgery.

Synthesis and biological evaluation of technetium-99m-labeled deoxyglucose derivatives as imaging agents for tumor

Three deoxyglucose (DG) derivatives, S-DG, MAG(3)-DG and MAMA-BA-DG, were synthesized and labeled successfully with high labeling yields and high radio-chemical purities. Biodistribution in tumor-bearing mice demonstrated that these three new (99m)Tc-deoxyglucose derivatives showed accumulation in tumor and high tumor-to-muscle ratios. Among them, the (99m)Tc-MAG(3)-DG showed the best characteristics as a potential tumor marker for single photon emission computed tomography (SPECT).

Posttreatment assessment of response using FDG-PET/CT for patients treated with definitive radiation therapy for head and neck cancers

PURPOSE

The goal of this study was to evaluate coregistered [18F] fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) for the detection of persistent disease after definitive radiation therapy in head and neck cancer.

METHODS AND MATERIALS

Posttreatment FDG-PET/CT was performed in 28 patients on average 8 weeks (range, 4 to 15.7 weeks) after completing definitive radiation therapy. FDG-PET/CT was visually analyzed for the entire patient group and at two time points (4-8 and >8 weeks) after treatment. The contrast-enhanced CT portion of PET/CT was separately analyzed blinded to the results of coregistered FDG-PET/CT and classified as negative or positive for residual locoregional disease. Pathologic findings and clinical follow-up served as the reference standard.

RESULTS

Follow-up data were available for all 28 patients (median, 17.6 months). Regarding the detection of residual disease, the overall sensitivity and specificity of FDG-PET/CT was 76.9% and 93.3%, respectively, compared with 92.3% and 46.7% for contrast-enhanced CT. The accuracy of FDG-PET/CT was 85.7%, compared with 67.9% for CT alone. All false-negative (n = 3) and false-positive (n = 1) FDG-PET/CT results occurred between 4 and 8 weeks after treatment. At 8 weeks or later after treatment, the specificity of CT was 28%, compared with 100% for FDG-PET/CT.

CONCLUSIONS

The metabolic-anatomic information from coregistered FDG-PET/CT provided the most accurate assessment for treatment response when performed later than 8 weeks after the conclusion of radiation therapy. FDG-PET/CT excelled by a higher specificity and overall diagnostic performance than CT imaging alone. These results support a potential clinical role of FDG-PET/CT in the early assessment of therapy response after definitive radiation therapy.