scholarly journals 18F-FDOPA PET/CT Uptake Parameters Correlate with Catecholamine Secretion in Human Pheochromocytomas

2018 ◽  
Vol 107 (3) ◽  
pp. 228-236 ◽  
Author(s):  
Sophie Moog ◽  
Sébastien Houy ◽  
Elodie Chevalier ◽  
Stéphane Ory ◽  
Georges Weryha ◽  
...  
Keyword(s):  
Tumor Volume ◽  
Primary Cultures ◽  
Nuclear Imaging ◽  
Real Time Measurement ◽  
Standardized Uptake Values ◽  
Positron Emission ◽  
Pet Ct ◽  
Single Center Study ◽  
The Mean ◽  
First Time

Background: 18F-FDOPA positron emission tomography/computed tomography (PET/CT) is a sensitive nuclear imaging technology for the diagnosis of pheochromocytomas (PHEO). However, its utility in determining predictive factors for the secretion of catecholamines remains poorly studied. Methods: Thirty-nine histologically confirmed PHEO were included in this retrospective single-center study. Patients underwent 18F-FDOPA PET/CT before surgery, with an evaluation of several uptake parameters (standardized uptake values [SUVmax and SUVmean] and the metabolic burden [MB] calculated as follows: MB = SUVmean × tumor volume) and measurement of plasma and/or urinary metanephrine (MN), normetanephrine (NM), and chromogranin A. Thirty-five patients were screened for germline mutations in the RET, SDHx, and VHL genes. Once resected, primary cultures of 5 PHEO were used for real-time measurement of catecholamine release by carbon fiber amperometry. Results: The MB of the PHEO positively correlated with 24-h urinary excretion of NM (r = 0.64, p < 0.0001), MN (r = 0.49, p = 0.002), combined MN and NM (r = 0.75, p < 0.0001), and eventually plasma free levels of NM (r = 0.55, p = 0.006). In the mutated patients (3 SDHD, 2 SDHB, 3 NF1, 1 VHL, and 3 RET), a similar correlation was observed between MB and 24-h urinary combined MN and NM (r = 0.86, p = 0.0012). For the first time, we demonstrate a positive correlation between the PHEO-to-liver SUVmax ratio and the mean number of secretory granule fusion events of the corresponding PHEO cells revealed by amperometric spikes (p = 0.01). Conclusion: While the 18F-FDOPA PET/CT MB of PHEO strongly correlates with the concentration of MN, amperometric recordings suggest that 18F-FDOPA uptake could be enhanced by overactivity of catecholamine exocytosis.

18-Fluoro-Deoxy-Glucose Positron Emission Tomography With Computed Tomography–Based Gross Tumor Volume Estimation and Validation With Magnetic Resonance Imaging for Locally Advanced Cervical Cancers

2012 ◽  
Vol 22 (6) ◽  
pp. 1031-1036 ◽  
Author(s):  
Maheshkumar N. Upasani ◽  
Umesh M. Mahantshetty ◽  
Venkatesh Rangarajan ◽  
Nilendu Purandare ◽  
Nikhil Merchant ◽  
...  
Keyword(s):  
Primary Tumor ◽  
Fdg Pet ◽  
Tumor Volume ◽  
Volume Estimation ◽  
Emission Tomography ◽  
Resonance Imaging ◽  
Positron Emission ◽  
Pet Ct ◽  
The Mean ◽  
Fdg Pet Ct

PurposeAnatomy and morphology–based imaging is routinely used for radiotherapy purpose to deliver precision treatment. There is an interest in using information from functional imaging for conformal radiation therapy planning. These functional imaging techniques need to be validated rigorously before their routine use. We attempted to evaluate and validate the use of 18-fluoro-deoxy-glucose positron emission tomography with computed tomography (18FDG PET-CT) on primary tumor of the cervical carcinoma, with an aim of arriving at a cutoff maximum standardized uptake value (SUVmax) at which the tumor volume correlates best with magnetic resonance imaging (MRI). This observational study was a part of an ethics committee–approved study evaluating pretreatment MRI and FDG PET-CT.Materials and MethodsPatients’ biopsy-proven cervical carcinomas (stages IIB and IIIB) were included in this study and underwent pretreatment MRI and FDG PET-CT as per institutional protocol. Volumes of the disease at the cervix on the MR image were calculated. Volumes at the FDG PET-CT scan at different percentages of SUVmax were auto contoured. Volume at MRI was correlated with each different percentage cutoff of the SUVmax.ResultsData of 74 patients were available for the study. The mean (SD) SUVmax of the primary tumor was 15.7 (7.0). The mean MRI volume correlates significantly (P < 0.001) with 30% and 35% of SUVmax values with good correlation according to the Pearson bivariate correlation (r = 0.79 each). The mean difference between MRI and PET volumes was least with 30% SUVmax.Conclusions18FDG PET-CT SUV-based primary tumor volume estimation at 30% to 35% of SUVmax values correlates significantly with the criterion standard MR volumes for primary cervical tumor with squamous histology in our population.

scholarly journals Changing Threshold-Based Segmentation Has No Relevant Impact on Semi-Quantification in the Context of Structured Reporting for PSMA-PET/CT

Cancers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 270
Author(s):  
Patrick W. Mihatsch ◽  
Matthias Beissert ◽  
Martin G. Pomper ◽  
Thorsten A. Bley ◽  
Anna K. Seitz ◽  
...  
Keyword(s):  
Tumor Volume ◽  
Bone Lesions ◽  
Primary Staging ◽  
Standardized Uptake Values ◽  
Positron Emission ◽  
Diagnostic Certainty ◽  
Psma Pet ◽  
Pet Ct ◽  
The Stability ◽  
Specific Membrane

Prostate-specific membrane antigen (PSMA)-directed positron emission tomography/computed tomography (PET/CT) is increasingly utilized for staging of men with prostate cancer (PC). To increase interpretive certainty, the standardized PSMA reporting and data system (RADS) has been proposed. Using PSMA-RADS, we characterized lesions in 18 patients imaged with 18F-PSMA-1007 PET/CT for primary staging and determined the stability of semi-quantitative parameters. Six hundred twenty-three lesions were categorized according to PSMA-RADS and manually segmented. In this context, PSMA-RADS-3A (soft-tissue) or -3B (bone) lesions are defined as being indeterminate for the presence of PC. For PMSA-RADS-4 and -5 lesions; however, PC is highly likely or almost certainly present [with further distinction based on absence (PSMA-RADS-4) or presence (PSMA-RADS-5) of correlative findings on CT]. Standardized uptake values (SUVmax, SUVpeak, SUVmean) were recorded, and volumetric parameters [PSMA-derived tumor volume (PSMA-TV); total lesion PSMA (TL-PSMA)] were determined using different maximum intensity thresholds (MIT) (40 vs. 45 vs. 50%). SUVmax was significantly higher in PSMA-RADS-5 lesions compared to all other PSMA-RADS categories (p ≤ 0.0322). In particular, the clinically challenging PSMA-RADS-3A lesions showed significantly lower SUVmax and SUVpeak compared to the entire PSMA-RADS-4 or -5 cohort (p < 0.0001), while for PSMA-RADS-3B this only applies when compared to the entire PSMA-RADS-5 cohort (p < 0.0001), but not to the PSMA-RADS-4 cohort (SUVmax, p = 0.07; SUVpeak, p = 0.08). SUVmean (p = 0.30) and TL-PSMA (p = 0.16) in PSMA-RADS-5 lesions were not influenced by changing the MIT, while PSMA-TV showed significant differences when comparing 40 vs. 50% MIT (p = 0.0066), which was driven by lymph nodes (p = 0.0239), but not bone lesions (p = 0.15). SUVmax was significantly higher in PSMA-RADS-5 lesions compared to all other PSMA-RADS categories in 18F-PSMA-1007 PET/CT. As such, the latter parameter may assist the interpreting molecular imaging specialist in assigning the correct PSMA-RADS score to sites of disease, thereby increasing diagnostic certainty. In addition, changes of the MIT in PSMA-RADS-5 lesions had no significant impact on SUVmean and TL-PSMA in contrast to PSMA-TV.

scholarly journals Validation of MR-Based Attenuation Correction of a Newly Released Whole-Body Simultaneous PET/MR System

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Guobing Liu ◽  
Tuoyu Cao ◽  
Lingzhi Hu ◽  
Jiaxu Zheng ◽  
Lifang Pang ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Attenuation Correction ◽  
Whole Body ◽  
Bone Lesions ◽  
Soft Tissue Lesions ◽  
Standardized Uptake Values ◽  
Positron Emission ◽  
Pet Ct ◽  
The Mean ◽  
Relative Differences

The aim of this study was to validate quantitative performance of a newly released simultaneous positron emission tomography (PET)/magnetic resonance imaging (MRI) scanner, by using MR-based attenuation correction (MRAC), both in phantom study and in patient study. PET/MRI image uniformities of a phantom under different hardware configurations were tested and compared. Thirty patients were examined with 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG) PET/computed tomography (CT) and subsequent PET/MRI. PET images from PET/MRI were corrected with MRAC (PETMR), CT-based attenuation maps (μ-maps, PETCT), and segmented CT μ-maps (PETCTSeg) derived from PET/CT. Standardized uptake values (SUVs) were compared among the 3 sets of PET in main organs (bone, liver and lung) and in 52 FDG-avid lesions, including soft-tissue lesions and bone lesions. The result showed that PET imaging uniformities of PET/MRI under different configurations were good (<8.8%). The SUV differences among the 3 sets of PET varied with organs and lesion types. In detail, the mean relative differences of SUV between PETMR and PETCT were as follows: −18.8%, bone (SUVmean); −8.0%, liver (SUVmean); −12.2%, lung (SUVmean); −18.1%, bone lesions (SUVmean); −13.3%, bone lesions (SUVmax); −8.2%, soft-tissue lesions (SUVmean); and −7.3%, soft-tissue lesions (SUVmax). The mean relative differences between PETMR and PETCTSeg were as follows: −19.0%, bone (SUVmean); −3.5%, liver (SUVmean); −3.3%, lung (SUVmean); −19.3%, bone lesions (SUVmean); −17.5%, bone lesions (SUVmax); −5.5%, soft-tissue lesions (SUVmean); and −4.4%, soft-tissue lesions (SUVmax). The differences of SUV between PETMR and PETCT were larger than those between PETMR and PETCTSeg, in both soft tissue and soft-tissue lesions (P<0.001), but not in bone or bone lesions. In conclusion, MRAC in the newly released PET/MR system is accurate in most tissues, with SUV deviations being generally less than 10%, compared to PET/CT. In bone, however, underestimations can be substantial, which may be partially attributed to segmentation of the MR-based μ-maps.

scholarly journals Significance of incidental intra-articular and peri-articular FDG avid foci on PET/CT

2018 ◽  
Vol 60 (1) ◽  
pp. 78-84
Author(s):  
Wayne B Cohen-Levy ◽  
Juan Pretell-Mazzini ◽  
Adam D Singer ◽  
Ty Subhawong ◽  
Dylan N Greif ◽  
...  
Keyword(s):  
Metastatic Disease ◽  
Statistical Significance ◽  
Metastatic Lesions ◽  
Standardized Uptake Values ◽  
Positron Emission ◽  
Pet Ct ◽  
Significant Difference ◽  
The Mean ◽  
The Difference ◽  
Pet Ct Scan

Background Positron emission tomography/computed tomography (PET/CT) is a useful imaging adjunct in patients with sarcoma. Intra-articular and peri-articular 18F-fluoro-2-deoxy-D-glucose (FDG) avid lesions are often discovered incidentally. Purpose To describe the etiology, appearance, and standardized uptake values (SUV) of incidentally detected FDG avid intra-articular and peri-articular foci in patients with sarcoma. Material and Methods The institutional sarcoma database between November 2011 and November 2016 was retrospectively reviewed. Patients were included if a PET/CT scan was performed and an FDG avid intra-articular or peri-articular focus was found that was distinct from the primary sarcoma. Results The majority of FDG avid foci represented benign, non-physiologic conditions such as osteoarthritis, enthesopathy, bursitis, and post-surgical changes. Six patients each had radiographic features consistent with tenosynovial giant cell tumor (TSGCT) and metastatic disease, respectively. Lower SUV, bilateral findings, and the absence of metastatic disease elsewhere were associated with benign etiologies. There was a statistically significant difference between the mean SUV measured in patients with TSGCT and those with benign, non-physiologic conditions ( P < 0.001). The difference between the benign, non-physiologic cohort and the cohort with widespread metastatic disease did not reach statistical significance ( P = 0.07). Conclusions In patients with soft-tissue or osseous sarcomas, isolated FDG avid intra-articular or peri-articular foci without additional metastatic lesions likely represent benign processes. Isolated intra-articular or peri-articular foci with significantly elevated SUV measurements were favored to represent TSGCT in this series.

scholarly journals Comparison of standardized uptake values measured on 18F-NaF PET/CT scans using three different tube current intensities

2015 ◽  
Vol 48 (1) ◽  
pp. 17-20 ◽  
Author(s):  
Agnes Araujo Valadares ◽  
Paulo Schiavom Duarte ◽  
Eduardo Bechtloff Woellner ◽  
George Barberio Coura-Filho ◽  
Marcelo Tatit Sapienza ◽  
...  
Keyword(s):  
Attenuation Correction ◽  
Lumbar Vertebra ◽  
Ct Scans ◽  
Femoral Diaphysis ◽  
Standardized Uptake Values ◽  
Pet Ct ◽  
Tube Current ◽  
The Mean ◽  
Humeral Diaphysis ◽  
Ct Studies

Objective: To analyze standardized uptake values (SUVs) using three different tube current intensities for attenuation correction on 18FNaF PET/CT scans. Materials and Methods: A total of 254 18F-NaF PET/CT studies were analyzed using 10, 20 and 30 mAs. The SUVs were calculated in volumes of interest (VOIs) drawn on three skeletal regions, namely, right proximal humeral diaphysis (RH), right proximal femoral diaphysis (RF), and first lumbar vertebra (LV1) in a total of 712 VOIs. The analyses covered 675 regions classified as normal (236 RH, 232 RF, and 207 LV1). Results: Mean SUV for each skeletal region was 3.8, 5.4 and 14.4 for RH, RF, and LV1, respectively. As the studies were grouped according to mAs value, the mean SUV values were 3.8, 3.9 and 3.7 for 10, 20 and 30 mAs, respectively, in the RH region; 5.4, 5.5 and 5.4 for 10, 20 and 30 mAs, respectively, in the RF region; 13.8, 14.9 and 14.5 for 10, 20 and 30 mAs, respectively, in the LV1 region. Conclusion: The three tube current values yielded similar results for SUV calculation.

Prostate and dominant intraprostatic lesion segmentation on PET/CT using cascaded regional-net

2021 ◽  
Author(s):  
Luke A Matkovic ◽  
Tonghe Wang ◽  
Yang Lei ◽  
Oladunni O Akin-Akintayo ◽  
Olayinka A Abiodun Ojo ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Cross Validation ◽  
Ct Images ◽  
Second Step ◽  
Prostate Segmentation ◽  
Positron Emission ◽  
Pet Ct ◽  
The Mean ◽  
And Training ◽  
Fold Cross Validation

Abstract Focal dose boost to dominant intraprostatic lesions (DILs) has recently been proposed for prostate radiation therapy. Accurate and fast delineation of the prostate and DILs is thus required during treatment planning. We propose a learning-based method using positron emission tomography (PET)/computed tomography (CT) images to automatically segment the prostate and its DILs. To enable end-to-end segmentation, a deep learning-based method, called cascaded regional-Net, is utilized. The first network, referred to as dual attention network (DAN), is used to segment the prostate via extracting comprehensive features from both PET and CT images. A second network, referred to as mask scoring regional convolutional neural network (MSR-CNN), is used to segment the DILs from the PET and CT within the prostate region. Scoring strategy is used to diminish the misclassification of the DILs. For DIL segmentation, the proposed cascaded regional-Net uses two steps to remove normal tissue regions, with the first step cropping images based on prostate segmentation and the second step using MSR-CNN to further locate the DILs. The binary masks of DILs and prostates of testing patients are generated from PET/CT by the trained network. To evaluate the proposed method, we retrospectively investigated 49 PET/CT datasets. On each dataset, the prostate and DILs were delineated by physicians and set as the ground truths and training targets. The proposed method was trained and evaluated using a five-fold cross-validation and a hold-out test. The mean surface distance and DSC values were 0.666±0.696mm and 0.932±0.059 for the prostate and 1.209±1.954mm and 0.757±0.241 for the DILs among all 49 patients. The proposed method has demonstrated great potential for improving the efficiency and reducing the observer variability of prostate and DIL contouring for DIL focal boost prostate radiation therapy.

scholarly journals Biodistribution PET/CT Study of Hemoglobin-DFO-89Zr Complex in Healthy and Lung Tumor-Bearing Mice

2020 ◽  
Vol 21 (14) ◽  
pp. 4991
Author(s):  
Łukasz Kiraga ◽  
Gabriele Cerutti ◽  
Agata Braniewska ◽  
Damian Strzemecki ◽  
Zuzanna Sas ◽  
...  
Keyword(s):  
Immune Cells ◽  
Lung Tumor ◽  
Drug Carrier ◽  
Drug Delivery Vehicles ◽  
Tumor Bearing ◽  
Selective Reaction ◽  
Positron Emission ◽  
Pet Ct ◽  
First Time ◽  
Very High

Proteins, as a major component of organisms, are considered the preferred biomaterials for drug delivery vehicles. Hemoglobin (Hb) has been recently rediscovered as a potential drug carrier, but its use for biomedical applications still lacks extensive investigation. To further explore the possibility of utilizing Hb as a potential tumor targeting drug carrier, we examined and compared the biodistribution of Hb in healthy and lung tumor-bearing mice, using for the first time 89Zr labelled Hb in a positron emission tomography (PET) measurement. Hb displays a very high conjugation yield in its fast and selective reaction with the maleimide-deferoxamine (DFO) bifunctional chelator. The high-resolution X-ray structure of the Hb-DFO complex demonstrated that cysteine β93 is the sole attachment moiety to the αβ-protomer of Hb. The Hb-DFO complex shows quantitative uptake of 89Zr in solution as determined by radiochromatography. Injection of 0.03 mg of Hb-DFO-89Zr complex in healthy mice indicates very high radioactivity in liver, followed by spleen and lungs, whereas a threefold increased dosage results in intensification of PET signal in kidneys and decreased signal in liver and spleen. No difference in biodistribution pattern is observed between naïve and tumor-bearing mice. Interestingly, the liver Hb uptake did not decrease upon clodronate-mediated macrophage depletion, indicating that other immune cells contribute to Hb clearance. This finding is of particular interest for rapidly developing clinical immunology and projects aiming to target, label or specifically deliver agents to immune cells.

Thyroid Incidentalomas on Fluorine-18-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography: Incidence, Malignancy Risk, and Comparison of Standardized Uptake Values

2012 ◽  
Vol 63 (4) ◽  
pp. 289-293 ◽  
Author(s):  
Yung H. Kao ◽  
Siew S. Lim ◽  
Seng C. Ong ◽  
Ajit K. Padhy
Keyword(s):  
Computed Tomography ◽  
Positron Emission Tomography ◽  
Fdg Pet ◽  
Emission Tomography ◽  
Thyroid Incidentaloma ◽  
Standardized Uptake Values ◽  
Positron Emission ◽  
Pet Ct ◽  
Fdg Pet Ct ◽  
Fluorine 18 Fluorodeoxyglucose

Introduction To determine the incidence of fluorine-18-fluorodeoxyglucose (FDG) avid thyroid incidentalomas detected on positron emission tomography (PET) with integrated computed tomography (CT), and correlate the FDG–PET-CT findings to cytology. Methods A total of 942 FDG–PET-CT reports were retrospectively reviewed. Patients with FDG-avid thyroid incidentalomas were further reviewed for correlative cytology. Results The incidence of FDG-avid thyroid incidentalomas is 2.2%. Thyroid malignancies were identified in 3 of 6 patients who underwent cytologic correlation, with a positive predictive value of 50% (95% confidence interval, 14%-86%). The mean maximum standardized uptake values of benign and malignant FDG-avid thyroid incidentalomas were 5.6 and 6.6, respectively. Conclusion A FDG-avid thyroid incidentaloma may predict underlying malignancy. Cytologic assessment should be considered for FDG-avid thyroid incidentalomas.

scholarly journals 68Ga-FAPI-04 Versus 18F-FDG PET/CT in the Detection of Hepatocellular Carcinoma

2021 ◽  
Vol 11 ◽  
Author(s):  
Hao Wang ◽  
Wenwei Zhu ◽  
Shuhua Ren ◽  
Yanyan Kong ◽  
Qi Huang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Fdg Pet ◽  
Tumour Size ◽  
Stromal Fibroblasts ◽  
Standardized Uptake Values ◽  
Positron Emission ◽  
Pet Ct ◽  
Epithelial Tumours ◽  
Fdg Pet Ct ◽  
Higher Sensitivity

BackgroundFibroblast activation protein (FAP) is commonly expressed in activated stromal fibroblasts in various epithelial tumours. Recently, 68Ga-FAPI-04 has been used for tumour imaging in positron emission tomography/computed tomography (PET/CT). This study aimed to compare the diagnostic performances of 68Ga-FAPI-04 PET/CT and 18F-FDG PET/CT in hepatocellular carcinoma (HCC), and to assess factors associated with 68Ga-FAPI-04 uptake in HCC.Materials and MethodsTwenty-nine patients with suspiciously HCC who received both 18F-FDG and 68Ga-FAPI-04 PET/CT were included in this retrospective study. The results were interpreted by two experienced nuclear medicine physicians independently. The maximum and mean standardized uptake values (SUVmax and SUVmean) were measured in the lesions and liver background, respectively. The tumour-to-background ratio (TBR) was then calculated as lesion’s SUVmax divided by background SUVmean.ResultsA total of 35 intrahepatic lesions in 25 patients with HCC were finally involved in the statistical analysis. 68Ga-FAPI-04 PET/CT showed a higher sensitivity than 18F-FDG PET/CT in detecting intrahepatic HCC lesions (85.7% vs. 57.1%, P = 0.002), including in small (≤ 2 cm in diameter; 68.8% vs. 18.8%, P = 0.008) and well- or moderately-differentiated (83.3% vs. 33.3%, P = 0.031) tumors. SUVmax was comparable between 68Ga-FAPI-04 and 18F-FDG (6.96 ± 5.01 vs. 5.89 ± 3.38, P &gt; 0.05), but the TBR was significantly higher in the 68Ga-FAPI-04 group compared with the 18F-FDG group (11.90 ± 8.35 vs. 3.14 ± 1.59, P &lt; 0.001). SUVmax and the TBR in 68Ga-FAPI-04 positive lesions were associated with tumour size (both P &lt; 0.05), but not the remaining clinical and pathological features (all P &gt; 0.05).Conclusions68Ga-FAPI-04 PET/CT is more sensitive than 18F-FDG PET/CT in detecting HCC lesions, and 68Ga-FAPI-04 uptake is correlated mainly with tumour size.

scholarly journals [F18] FDG-PET/CT for manual or semiautomated GTV delineation of the primary tumor for radiation therapy planning in patients with esophageal cancer: is it useful?

2020 ◽  
Author(s):  
Franziska Walter ◽  
Constanze Jell ◽  
Barbara Zollner ◽  
Claudia Andrae ◽  
Sabine Gerum ◽  
...  
Keyword(s):  
Esophageal Cancer ◽  
Primary Tumor ◽  
Fdg Pet ◽  
Interobserver Variability ◽  
Target Volume ◽  
Standardized Uptake Values ◽  
Positron Emission ◽  
Pet Ct ◽  
Significant Difference ◽  
Fdg Pet Ct

Abstract Background Target volume definition of the primary tumor in esophageal cancer is usually based on computed tomography (CT) supported by endoscopy and/or endoscopic ultrasound and can be difficult given the low soft-tissue contrast of CT resulting in large interobserver variability. We evaluated the value of a dedicated planning [F18] FDG-Positron emission tomography/computer tomography (PET/CT) for harmonization of gross tumor volume (GTV) delineation and the feasibility of semiautomated structures for planning purposes in a large cohort. Methods Patients receiving a dedicated planning [F18] FDG-PET/CT (06/2011–03/2016) were included. GTV was delineated on CT and on PET/CT (GTVCT and GTVPET/CT, respectively) by three independent radiation oncologists. Interobserver variability was evaluated by comparison of mean GTV and mean tumor lengths, and via Sørensen–Dice coefficients (DSC) for spatial overlap. Semiautomated volumes were constructed based on PET/CT using fixed standardized uptake values (SUV) thresholds (SUV30, 35, and 40) or background- and metabolically corrected PERCIST-TLG and Schaefer algorithms, and compared to manually delineated volumes. Results 45 cases were evaluated. Mean GTVCT and GTVPET/CT were 59.2/58.0 ml, 65.4/64.1 ml, and 60.4/59.2 ml for observers A–C. No significant difference between CT- and PET/CT-based delineation was found comparing the mean volumes or lengths. Mean Dice coefficients on CT and PET/CT were 0.79/0.77, 0.81/0.78, and 0.8/0.78 for observer pairs AB, AC, and BC, respectively, with no significant differences. Mean GTV volumes delineated semiautomatically with SUV30/SUV35/SUV40/Schaefer’s and PERCIST-TLG threshold were 69.1/23.9/18.8/18.6 and 70.9 ml. The best concordance of a semiautomatically delineated structure with the manually delineated GTVCT/GTVPET/CT was observed for PERCIST-TLG. Conclusion We were not able to show that the integration of PET/CT for GTV delineation of the primary tumor resulted in reduced interobserver variability. The PERCIST-TLG algorithm seemed most promising compared to other thresholds for further evaluation of semiautomated delineation of esophageal cancer.

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