Search

Background/aim The aim of this study was to evaluate the value of PET Vascular Activity Score (PETVAS) during the follow-up of patients with Takayasu arteritis. Materials and methods Takayasu arteritis patients who underwent 18F-Fluorodeoxyglucose (FDG) PET imaging were evaluated retrospectively. In 8 patients both 1 and 2-hour imagings were also performed prospectively. For PETVAS, 9 arterial areas were scored between 0-3 according to the FDG uptake. Results Forty-six images of 34 patients were evaluated. PETVAS was higher in patients with clinically active disease (p=0.03) and in C-reactive protein (CRP) elevated group among clinically inactive patients (p=0.0015). PETVAS correlated with CRP (p=0.003, r=0.53) and erythrocyte sedimentation rate (p=0.005, r=0.41), whereas age, disease duration, immunosuppressive and glucocorticoid (GC) treatments were not associated with PETVAS. First vs 2nd-hour PETVAS was similar in patients who had both 1st and 2nd hour PET scans (p=0.67). Conclusion We observed higher PETVAS in patients with active disease and elevated acute phase reactants. Although scores in our study (performed at one-hour) were lower compared to the original PETVAS study performed at two hours, PETVAS seems to be a reliable tool to quantify FDG PET scores in routine practice.

Background To study the possible relation between immunohistochemical expression of vascular endothelial growth factor receptor 1 (VEGFR1) and the maximum standardised uptake value (SUV max) of 18F-FDG PET in patients with non small cell lung cancer (NSCLC). Material and Methods The study included 39 patients with NSCLC (24 squamous cell carcinomas and 15 adenocarcinomas). According to the clinical stage, the patients were distributed as follows: 8 stage I, 7 stage II, 15 stage III and 9 stage IV. Immunohistochemical expression of VEGFR1 was studied through the technique of tissue-matrix using Tissue Arrayer Device (Beecher Instruments, Sun Prairie, WI), using the polyclonal antibody against VEGFR1 (Santa Cruz Biotechnology, California, USA). Results Positive VEGFR1 immunohistochemical expression was noted in 23 cases (59%). The number of positive tumours was not related with clinical stage but there was a different statistically significant association (p:0,0009) between VEGFR1 positivity and histological type, corresponding the greater percentages of positive results to adenocarcinomas (93,3%) versus in squamous cell carcinomas (37,5%). Likewise, SUV max values were higher (p: 0,039) in negative VEGFR1 carcinomas than in positive VEGFR1 tumors (r: 4-32,1; 16,4+/-6,4 (median 16,1) vs r: 3-47; 14,5+/-8,6 (12,8)). Conclusions Our results led us to consider that in NSCLC, the negative VEGFR1 immunohistochemical expression is associated significantly with squamous cell carcinomas subtype and with higher SUV max values in 18F-FDG-PET.

Background PET imaging has been widely used in diagnosis of neurological disorders; however, its application to pediatric population is limited due to lacking pediatric age–specific PET template. This study aims to develop a pediatric age–specific PET template (PAPT) and conduct a pilot study of epileptogenic focus localization in pediatric epilepsy. Methods We recruited 130 pediatric patients with epilepsy and 102 age-matched controls who underwent 18F-FDG PET examination. High-resolution PAPT was developed by an iterative nonlinear registration-averaging optimization approach for two age ranges: 6–10 years (n = 17) and 11–18 years (n = 50), respectively. Spatial normalization to the PAPT was evaluated by registration similarities of 35 validation controls, followed by estimation of potential registration biases. In a pilot study, epileptogenic focus was localized by PAPT-based voxel-wise statistical analysis, compared with multi-disciplinary team (MDT) diagnosis, and validated by follow-up of patients who underwent epilepsy surgery. Furthermore, epileptogenic focus localization results were compared among three templates (PAPT, conventional adult template, and a previously reported pediatric linear template). Results Spatial normalization to the PAPT significantly improved registration similarities (P P n = 40), the PAPT-based localization also achieved a substantial agreement with resection areas (Kappa = 0.743), and the highest detection rate (95%) and accuracy (80.0%). Conclusion The PAPT can significantly improve spatial normalization and epileptogenic focus localization in pediatric epilepsy. Future pediatric neuroimaging studies can also benefit from the unbiased spatial normalization by PAPT. Trial registration. NCT04725162: https://clinicaltrials.gov/ct2/show/NCT04725162

espanolObjetivo Nuestro proposito es establecer el valor pronostico de los parametros metabolicos del tumor primario en pacientes diagnosticadas de carcinoma vulvar de celulas escamosas (VSCC) en las que se realizo un 18F-FDG PET/TC pretratamiento. Materiales y metodos Estudio retrospectivo que incluyo 47 pacientes con un diagnostico histopatologico confirmado de VSCC en las que se realizo un 18F-FDG PET/TC antes del tratamiento. Se registraron la fase de la enfermedad, la edad de diagnostico y el valor estandarizado de captacion maximo (SUVmax), los valore de SUVmean, del volumen de tumor metabolico (MTV) y de la glucolisis total de la lesion (TLG) del tumor primario, segun una PET basal. Se evaluo la relacion entre estos factores, la supervivencia libre de progresion (PFS) y la supervivencia global (OS). Resultados La edad media de las 47 pacientes del estudio era de 69,6 ± 1,9 anos. Entre las pacientes, 18 estaban en la fase inicial de la enfermedad y 29 estaban en fase avanzada. La edad y los valores de SUVmax, SUVmean, MTV y TLG estaban asociados de forma estadisticamente significativa con la OS y PFS. Ademas, se observo que OS y PFS era significativamente mayor en las pacientes en fases iniciales que en las pacientes en fase avanzada; en pacientes con un tamano del tumor Conclusion Nuestros resultados sugieren que los parametros de la PET son factores pronosticos del VSCC. Hasta donde sabemos, este estudio es el primero en investigar el valor pronostico de los parametros PET de los tumores primarios en pacientes con VSCC, y por esta razon, creemos que contribuye a la literatura especializada. EnglishPurpose We aim to establish the prognostic value of metabolic parameters of the primary tumor in patients diagnosed with vulvar squamous cell carcinoma (VSCC) who underwent a pretreatment 18F FDG PET/CT scan. Materials and methods This retrospective study included 47 patients with a histopathologically confirmed diagnosis of VSCC, and who underwent a 18F FDG PET/CT scan prior to treatment. The disease stage and age at diagnosis, the maximum standardized uptake value (SUVmax), SUVmean, metabolic tumor volume (MTV) and total lesion glycolysis (TLG) values of the primary tumor, based on a baseline PET scan, were recorded. The relationship between these factors, and progression-free survival (PFS) and overall survival (OS) was evaluated. Results The mean age of the 47 study patients was 69.6 ± 1.9 years. Among the patients, 18 were in early stage of the disease and 29 were in the advanced stage. The age, and SUVmax, SUVmean, MTV and TLG values were statistically significantly associated with OS and PFS. Furthermore, it was noted that OS and PFS were significantly longer in the early stage patients than in the advanced stage patients, in patients with a tumor size Conclusion Our findings suggest that PET parameters are prognostic factors for VSCC. To the best of our knowledge, this study is the first to investigate the prognostic value of the PET parameters of primary tumors in patients with VSCC, and as such, we believe it contributes to literature.

A young gentleman with suspected cardiac sarcoidosis and LV dysfunction whose CMR revealed multifocal subepicardial to mid myocardial linear enhancement in the left ventricular myocardium underwent cardiac 18F-FDG PET imaging. The images revealed patchy regions of increased FDG uptake involving the apical to mid anterolateral, mid to basal anteroseptal/ right ventricular and mildly increased FDG uptake in apical inferior segments of the LV myocardium concordant with CMR findings. Whole body PET CT imaging showed multiple hypermetabolic supra and infra diaphragmatic lymphadenopathy, with no pulmonary lesion identified. Biopsy from the left para aortic lymph node revealed necrotizing granulomatous inflammation consistent with tuberculosis. Based on the histopathological findings of the lymph nodes, diagnosis of cardiac tuberculosis was made, given the similar imaging appearances in both sarcoidosis and TB. This case highlights that cardiac TB although rare, should be included in the differential diagnosis in patients with suspected infiltrative cardiomyopathy, particularly in TB endemic regions.

Purpose To investigate the prognostic value of interim PET (PETi) in adult HL patients, comparing visual with semiquantitative analysis. Material and methods Retrospective analysis of Hodgkin's lymphoma (HL) patients diagnosed between 2012 and 2016 in the Onco-hematology Department of Instituto Portugues de Oncologia – Porto (median follow-up: 46.5 months [2.6–66.4]). Fifty-eight patients with available PET at diagnosis (PET0) and PETi data were included. PETi scans were analyzed according to Deauville 5-point scale (5-PS), and cut-off values for changes in maximum standardized uptake value [SUVmax], peak SUV [SUVpeak], metabolic tumour volume [MTV] and total lesion glycolysis index [TLG] between PETi and PET0 were computed using ROC analysis. Visual and semiquantitative data were compared with each other in the prediction of patient outcomes. Results Semiquantitative analysis obtained a higher sensitivity for persistent/relapsed disease compared to the 5-PS (70% vs. 10%, respectively), but lower specificity. It also demonstrated better predictive performance for response to first-line therapy (negative predictive value >92%). The positive predictive value was similar for all five measurements. At 60 months of follow-up, there was a significant difference between the progression free survival (PFS) curves of patients with positive and negative PETi according to ΔSUVmax (56.9% vs. 88.0%, p Discussion PETi interpretation according to a semiquantitative approach appears to discriminate HL patients better than the visual 5-PS analysis. This could allow better detection of persistent or early relapsed disease, while a negative PETi result could support de-escalating therapy intensity.

Background Due to partly conflicting studies, further research is warranted with the QGS software package, with regard to the performance of gated FDG PET phase analysis as compared to gated MPS as well as the establishment of possible cut-off values for FDG PET to define dyssynchrony. Methods Gated MPS and gated FDG PET datasets of 93 patients were analyzed with the QGS software. BW, Phase SD, and Entropy were calculated and compared between the methods. The performance of gated PET to identify dyssynchrony was measured against SPECT as reference standard. ROC analysis was performed to identify the best discriminator of dyssynchrony and to define cut-off values. Results BW and Phase SD differed significantly between the SPECT and PET. There was no significant difference in Entropy with a high linear correlation between methods. There was only moderate agreement between SPECT and PET to identify dyssynchrony. Entropy was the best single PET parameter to predict dyssynchrony with a cut-off point at 62%. Conclusion Gated MPS and gated FDG PET can assess LVMD. The methods cannot be used interchangeably. Establishing reference ranges and cut-off values is difficult due to the lack of an external gold standard. Further prospective research is necessary.

Background Considering the limited accessibility of amyloid position emission tomography (PET) in patients with dementia, we proposed a deep learning (DL)-based amyloid PET positivity classification model from PET images with 2-deoxy-2-[fluorine-18]fluoro-D-glucose (2-[18F]FDG). Methods We used 2-[18F]FDG PET datasets from the Alzheimer's Disease Neuroimaging Initiative and Korean Brain Aging Study for the Early diagnosis and prediction of Alzheimer’s disease for model development. Moreover, we used an independent dataset from another hospital. A 2.5-D deep learning architecture was constructed using 291 submodules and three axes images as the input. We conducted the voxel-wise analysis to assess the regions with substantial differences in glucose metabolism between the amyloid PET-positive and PET-negative participants. This facilitated an understanding of the deep model classification. In addition, we compared these regions with the classification probability from the submodules. Results There were 686 out of 1433 (47.9%) and 50 out of 100 (50%) amyloid PET-positive participants in the training and internal validation datasets and the external validation datasets, respectively. With 50 times iterations of model training and validation, the model achieved an AUC of 0.811 (95% confidence interval (CI) of 0.803–0.819) and 0.798 (95% CI, 0.789–0.807) on the internal and external validation datasets, respectively. The area under the curve (AUC) was 0.860 when tested with the model with the highest value (0.864) on the external validation dataset. Moreover, it had 75.0% accuracy, 76.0% sensitivity, 74.0% specificity, and 75.0% F1-score. We found an overlap between the regions within the default mode network, thus generating high classification values. Conclusion The proposed model based on the 2-[18F]FDG PET imaging data and a DL framework might successfully classify amyloid PET positivity in clinical practice, without performing amyloid PET, which have limited accessibility.

Introduction Takotsubo syndrome (TTS) is triggered mostly by physical and/or emotional stress that is processed in stress-associated brain regions, including the amygdala. However, it remains unclear whether such stress-induced brain activity is associated with TTS onset. Methods and results We acquired brain [18F]-2-fluoro-deoxy- d -glucose (18F-FDG) positron emission tomography in 4 TTS patients (44–82 yrs., 3 women) on days 2–4 (acute phase) and days 29–40 (recovery phase) after diagnosis of TTS was made by coronary angiography and left ventriculogram. The 18F-FDG uptake was measured globally and also in the pre-defined regions of interest of the bilateral amygdala on the common Montreal Neurological Institute space; all 18F-FDG images were normalized using automated image pre-processing. Amygdalar activity was calculated by dividing the 18F-FDG uptake of the amygdala by the global brain uptake. Left ventriculograms showed that apical ballooning was typical at diagnosis and was then relieved in the recovery phase. Amygdalar activity in the acute phase (0.872 ± 0.032) was higher than in the recovery phase (0.805 ± 0.037) (P = 0.013). Conclusions We report here 4 cases of TTS showing higher amygdalar activity in the acute phase as compared with the recovery phase, suggesting that increased stress-induced neurobiological activity is associated with TTS onset.

Non-invasive positron emission tomography (PET) of vascular inflammation and atherosclerotic plaque by identifying increased uptake of 18F-fluordeoxyglucose (18F-FDG) is a powerful tool for monitoring disease activity, progression, and its response to therapy. 18F-FDG PET/computed tomography (PET/CT) of the aorta and carotid arteries has become widely used to assess changes in inflammation in clinical trials. However, the recent advent of hybrid PET/magnetic resonance (PET/MR) scanners has advantages for vascular imaging due to the reduction in radiation exposure and improved soft tissue contrast of MR compared to CT. Important for research and clinical use is an understanding of the scan-rescan repeatability of the PET measurement. While this has been studied for PET/CT, no data is currently available for vascular PET/MR imaging. In this study, we determined the scan-rescan measurement repeatability of 18F-FDG PET/MR in the aorta and carotid arteries was less than 5%, comparable to similar findings for 18F-FDG PET/CT.

Objectives The aim of this study was to investigate the value of [18F]fluoro-2-deoxy-D-glucose (18F-FDG) PET/computed tomography (CT) to detect recurrent cervical neuroendocrine carcinoma and its subsequent impact on patient management. Methods A total of 25 patients who had undergone 30 18F-FDG PET/CT studies for suspected recurrent cervical neuroendocrine carcinoma (18 small cells, 2 large cells, 1 atypical carcinoid, and 4 unclassified) were retrospectively analyzed. The findings of the PET/CT images were compared with the histopathologic results in 8 scans and with clinical follow-up in 22 scans. Results Of the 30 PET/CT studies, 63.3% (19/30) were positive for recurrence while 36.7% (11/30) were negative. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 18F-FDG PET/CT for detecting recurrent disease of cervical neuroendocrine carcinomas were 90.0, 90.0, 94.7, 81.8, and 90.0%, respectively. Metastasis to distant organs was the most common (89.4%), followed by lymph node recurrence (52.6%). Lungs were the most frequent site of distant metastasis (63.1%). 18F-FDG PET/CT findings led to the change of the management in 10 out of 25 patients (40%) by introducing the use of previously unplanned therapeutic procedures. Conclusions 18F-FDG PET/CT is an efficient technique for detecting recurrent cervical neuroendocrine carcinoma, and may thus contribute to improving patient management.

Introduction and Objectives Since different PET/CT (Positron Emission Tomography/Computed Tomography) scanners give different qualitative readings, a program for clinical trial qualification (CTQ) is mandatory to guarantee a reliable and reproducible use of PET/CT in prospective multi-centre clinical trials. Within this work we will show the results carried out in performing CTQ in Spain. Materials and Methods We set up, under the auspices of Grupo Espanol de Linfomas/Trasplante Autologo de Medula Osea (GELTAMO), a CTQ program consisting of the acquisition and analysis of 18 F uniformity and image quality phantoms for the reduction of inter-scanner variability (ISV). The ISV was estimated on background activity concentration (BAC) and sphere to background ratio (SBR) and defined as their 95% confidence level. Results Twenty-six out of 27 (96%) scanners fulfilled the CTQ requirements. The CTQ was fulfilled at the first round in 27% of the cases, while in 38%, 15% and 20%, two, three or more than three iterations, were required, respectively. The mean CTQ time was (1.8 ± 1.4) months (range: 0.3–4.6). The ISV in BAC and SBR were 20.3% and 67.7%. Conclusions The CTQ proven to be a reliable tool to reduce ISV. This enabled to set-up clinical trials in which PET/CT was used to evaluate different clinical endpoints.

Background Dynamic PET with kinetic modeling was reported to be potentially helpful in the assessment of hepatic malignancy. In this study, a kinetic modeling analysis was performed on hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) from dynamic FDG positron emission tomography/computer tomography (PET/CT) scans. Methods A reversible two-tissue compartment model with dual blood input function, which takes into consideration the blood supply from both hepatic artery and portal vein, was used for accurate kinetic modeling of liver dynamic 18F-FDG PET imaging. The blood input functions were directly measured as the mean values over the VOIs on descending aorta and portal vein respectively. And the contribution of hepatic artery to the blood input function was optimization-derived in the process of model fitting. The kinetic model was evaluated using dynamic PET data acquired on 24 patients with identified hepatobiliary malignancy. 38 HCC or ICC identified lesions and 24 healthy liver regions were analyzed. Results Results showed significant differences in kinetic parameters $${K}_{1}-{k}_{4}$$ K 1 - k 4 , blood supplying fraction $${f}_{A}$$ f A , and metabolic rate constant $${K}_{i}$$ K i between malignant lesions and healthy liver tissue. And significant differences were also observed in $${K}_{1}$$ K 1 , $${k}_{3}$$ k 3 , $${f}_{A}$$ f A and $${K}_{i}$$ K i between HCC and ICC lesions. Further investigations of the effect of SUV measurements on the derived kinetic parameters were conducted. And results showed comparable effectiveness of the kinetic modeling using either SUVmean or SUVmax measurements. Conclusions Dynamic 18F-FDG PET imaging with optimization-derived hepatic artery blood supply fraction dual-blood input function kinetic modeling can effectively distinguish malignant lesions from healthy liver tissue, as well as HCC and ICC lesions.

IntroductionThere is no consensus about the standardized uptake value maximum (SUVmax) cut-off value to characterize pleural thickening worldwide. Sometimes, this causes unnecessary invasive diagnostic procedures. Our first aim is to determine a cut-off value for SUVmax. Secondly, we try to answer the following question: If we use this cut-off value together with morphological parameters, can we differentiate benign thickening from malignant pleural mesothelioma (MPM) more accurately?Material and methodsThirty-seven patients who underwent 2-deoxy-2-fluoro-D-glucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) before pleural biopsy were included the study. All of patients had histopathologically proven primary pleural disease. Their [18F]FDG-PET/CT imaging reports were re-assessed. If a patient’s SUVmax or size of the thickening was not mentioned in the report, we calculated it with their [18F]FDG-PET/CT.ResultsAge, pleural effusion, size, and SUVmax were found to have a relationship with MPM. We found the size > 14 mm, and SUVmax > 4.0 as cut-off values for MPM. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for size > 14 mm were found to be 86.4%, 85.2%, 82.6%, 88.5%, respectively. For SUVmax > 4.0, sensitivity, specificity, PPV, NPV were 90.9%, 87.0%, 85.1%, 92.2%, respectively.ConclusionsIf a patient has SUVmax > 4.0 and/or size > 14 mm, the risk of MPM is high. These patients should undergo biopsy. If a patient’s SUVmax < 4.0, size < 14 mm and does not have pleural effusion, he/she has low risk for MPM. These patients can undergo the follow-up. If a patient’s SUVmax < 4, size < 14, and has pleural effusion the MPM risk is approximately 4%. These patients can undergo biopsy/cytology/follow-up. Novel studies are needed for these patients.

[11C]UCB-J PET for synaptic vesicle glycoprotein 2 A (SV2A) has been proposed as a suitable marker for synaptic density in Alzheimer’s disease (AD). We compared [11C]UCB-J binding for synaptic density and [18F]FDG uptake for metabolism (correlated with neuronal activity) in 14 AD and 11 cognitively normal (CN) participants. We assessed both absolute and relative outcome measures in brain regions of interest, i.e., K1 or R1 for [11C]UCB-J perfusion, VT (volume of distribution) or DVR to cerebellum for [11C]UCB-J binding to SV2A; and Ki or Ki R to cerebellum for [18F]FDG metabolism. [11C]UCB-J binding and [18F]FDG metabolism showed a similar magnitude of reduction in the medial temporal lobe of AD –compared to CN participants. However, the magnitude of reduction of [11C]UCB-J binding in neocortical regions was less than that observed with [18F]FDG metabolism. Inter-tracer correlations were also higher in the medial temporal regions between synaptic density and metabolism, with lower correlations in neocortical regions. [11C]UCB-J perfusion showed a similar pattern to [18F]FDG metabolism, with high inter-tracer regional correlations. In summary, we conducted the first in vivo PET imaging of synaptic density and metabolism in the same AD participants and reported a concordant reduction in medial temporal regions but a discordant reduction in neocortical regions.

We used18F-FDG-PET to investigate the frequency of crossed cerebellar diaschisis (CCD) in 197 patients with various syndromes associated with neurodegenerative diseases. In a subset of 117 patients, we studied relationships between CCD and cortical asymmetry of Alzheimer’s pathology (β-amyloid (11C-PIB) and tau (18F-Flortaucipir)). PET images were processed using MRIs to derive parametric SUVR images and define regions of interest. Indices of asymmetry were calculated in the cerebral cortex, basal ganglia and cerebellar cortex. Across all patients, cerebellar18F-FDG asymmetry was associated with reverse asymmetry of18F-FDG in the cerebral cortex (especially frontal and parietal areas) and basal ganglia. Based on our operational definition (cerebellar asymmetry >3% with contralateral supratentorial hypometabolism), significant CCD was present in 47/197 (24%) patients and was most frequent in corticobasal syndrome and semantic and logopenic variants of primary progressive aphasia. In β-amyloid-positive patients, mediation analyses showed that18F-Flortaucipir cortical asymmetry was associated with cerebellar18F-FDG asymmetry, but that cortical18F-FDG asymmetry mediated this relationship. Analysis of18F-FDG-SUVR values suggested that CCD might also occur in the absence of frank cerebellar18F-FDG asymmetry due to symmetrical supratentorial degeneration resulting in a bilateral diaschisis process.

Encephaloceles, also known as meningoencephaloceles, are a group of neurological disorders characterized by herniation of the cerebral parenchyma along with overlying meninges through openings in the skull bone. They can be seen following congenital defect in neural tube closure or acquired defect in the skull bone. We report a case of acquired frontoethmoidal encephalocele presenting with drug-refractory epilepsy. Interictal FDG PET-computed tomography done for lateralization and localization of seizure focus showed right-sided frontoethmoidal encephalocele associated with hypometabolism in the adjacent right frontopolar cortex, concordant with ictal onset on electroencephalogram.

PurposeTo conduct a head-to-head comparison of the diagnostic ability of 68Ga-DOTA-FAPI-04 (68Ga-FAPI) and 18F-FDG PET/MR in nasopharyngeal carcinoma (NPC) patients.MethodsPatients diagnosed with NPC were prospectively enrolled. All patients underwent head-and-neck 68Ga-FAPI PET/MR and 18F-FDG PET/MR within one week. Primary tumor, lymph node numbers, and tracer uptake were compared by SUVmax and visual evaluation. The primary tumor volumes derived from 68Ga-FAPI, 18F-FDG PET, and MRI were also compared.ResultsFifteen patients were enrolled from June to August 2020. Both 68Ga-FAPI and 18F-FDG PET had 100% detection rate of the primary tumor. The 68Ga-FAPI SUVmax of primary tumors (13.87±5.13) was lower than that of 18F-FDG (17.73±6.84), but the difference was not significant (p=0.078). Compared with 18F-FDG, 68Ga-FAPI PET improved the delineation of skull-base invasion in eight out of eight patients and intracranial invasion in four out of four patients. When 25%SUVmax of 68Ga-FAPI or 20%SUVmax of 18F-FDG was utilized as a threshold for determining tumor volume, it was highly consistent with MRI. 18F-FDG PET detected much more positive lymph nodes than 68Ga-FAPI (100 vs 48). The SUVmax of 48 paired lymph nodes was significantly lower on 68Ga-FAPI than 18F-FDG (8.67±3.88 vs 11.79±6.17, p68Ga-FAPI further detected four highly suspected small, distant metastases in three patients. Compared with 18F-FDG, 68Ga-FAPI changed overall staging in six of fifteen patients, with three patients being up-staged, and three down-staged.Conclusion68Ga-FAPI outperforms 18F-FDG in delineating the primary tumor and detecting suspected distant metastases, particularly in the evaluation of skull-base and intracranial invasion, suggesting 68Ga-FAPI hybrid PET/MR has the potential to serve as a single-step staging modality for patients with NPC. However, its value regarding lymph node and distant metastases evaluation needs further study.Trial registration: NCT04554719. Registered September 8, 2020 - retrospectively registered, http://clinicaltrails.gov/show/ NCT04554719

Rationale: Whether assessment of potential bone lesions in metastatic breast cancer (MBC) by means of 18F-fluorodeoxyglucose (FDG)-PET instead of 99mTechnetium (99mTc) bone scintigraphy (BS) supports clinically relevant changes in MBC management, is currently unknown. Therefore, we retrospectively compared the management recommendations based on bone lesion assessment by FDG-PET plus contrast enhanced computed tomography (ceCT) or BS plus ceCT, for patients with newly diagnosed MBC. Methods: Baseline ceCT, BS and FDG-PET of all patients included in the IMPACT-MBC study (NCT01957332) at location University Medical Center Groningen (UMCG), were reviewed for bone lesions. In case of bone lesions on any imaging modality, virtual MBC management recommendations per patient were made by a multidisciplinary expert panel, based on either FDG-PET plus ceCT, or BS plus ceCT. The panel had access to standard clinicopathological information and baseline imaging findings outside the skeleton. Clinically relevant management differences between the two recommendations were defined as 1) different treatment intent, (curative, non-curative or unable to determine and/or 2) different systemic or local treatment. In case of absence of bone lesions with any imaging modality, patients were included in the analyses without expert review. Results: A total of 3,473 unequivocal bone lesions was identified in 102 evaluated patients (39% by ceCT, 26% by BS, 87% by FDG-PET). Additional bone lesions on FDG-PET plus ceCT compared to BS plus ceCT led to change of MBC management recommendations in 16% of all patients (95% confidence interval (CI) 10-24%). BS also changed management compared to FDG-PET in one patient (1%; 95%CI 0-5%). In 26% (95%CI 19-36%) of patients, an additional FDG-PET was requested, because BS provided insufficient information. Conclusion: In this exploratory analysis of newly diagnosed MBC patients, FDG-PET versus BS to assess bone lesions, resulted in clinically relevant management differences in 16% of all patients. BS delivered insufficient information in over one fourth of patients, resulting in additional request for FDG-PET. Based on this data, FDG-PET should be considered as primary imaging modality for assessment of bone lesions in newly diagnosed MBC.

OBJECTIVES We performed a systematic review and meta-analysis to evaluate the impact of 18F-FDG PET, PET/CT, and PET/MRI on staging and management during the initial staging of breast cancer. METHODS We searched the PubMed, Embase, Cochrane Library, and KoreaMed databases until March 2020 to identify studies that reported the proportion of breast cancer patients whose clinical stage or management were changed after PET scans. The proportion of changes was pooled using a random-effects model. Subgroup and metaregression analyses were performed to explore heterogeneity. RESULTS We included 29 studies (4276 patients). The pooled proportions of changes in stage and management were 25% (95% confidence interval [CI], 21%-30%) and 18% (95% CI, 14%-23%), respectively. When stage changes were stratified according to initial stage, the pooled proportions were 11% (95% CI, 3%-22%) in stage I, 20% (95% CI, 16%-24%) in stage II, and 34% (95% CI, 27%-42%) in stage III. The relative proportions of intermodality and intention-to-treat changes were 74% and 70%, respectively. Using metaregression analyses, the mean age and the proportion of initial stage III to IV and histologic grade II to III were significant factors affecting the heterogeneity in changes in stage or management. CONCLUSIONS Currently available literature suggests that the use of 18F-FDG PET, PET/CT, or PET/MRI leads to significant modification of staging and treatment in newly diagnosed breast cancer patients. Therefore, there may be a role for routine clinical use of PET imaging for the initial staging of breast cancer.

To compare the accuracy of contrast-enhanced MRI using established dimensional and morphological criteria versus integrated [18F]FDG PET/MRI in identifying regional lymph node metastases in patients with newly diagnosed head and neck squamous cell carcinoma (HNSCC). For this purpose, we compare MRI and PET/MRI using the histopathological findings in dissected lymph nodes as the gold standard. We retrospectively reviewed 26 patients with histologically proven HNSCC who underwent gadolinium-enhanced [18F]FDG PET/MRI as part of their staging. All neck lymph nodes were classified on MRI using dimensional and/or morphological criteria. Then, they were jointly assessed by a nuclear medicine physician and a radiologist using integrated [18F]PET/MR images. ROC curves were obtained to compare the techniques. Lymph node histopathology was considered as the reference standard. Out of 865 lymph nodes, 35 were malignant at histopathology (3 with micro-metastases). Sensitivity and specificity were 48.6% and 99.5% for MRI using dimensional criteria; 60.0% and 99.6% for MRI using morphological criteria; 60.0% and 99.4% for MRI using both; and 74.3% and 97.6% for PET using MR as anatomic localization. The area under the ROC curve was higher for PET and MRI localization (0.859) than for MRI using dimensional (0.740; p

In 2005, Nestle et al. ([1][1]) published their seminal paper comparing different methods to delineate radiotherapy target volume from 18F-FDG PET in non–small cell lung cancer (NSCLC). They compared 4 different methods for primary delineation of gross-tumor target volume: a visual method, 2 fixed

A 65-year-old man with fluciclovine-avid metastatic prostate small cell carcinoma with prostate-specific antigen (PSA) 19.4 ng/mL at diagnosis underwent system therapy and subsequent surgery and achieved hormonal response with PSA

Purpose Early indication of treatment outcome may guide therapeutic de-escalation strategies in patients with human papillomavirus (HPV)-related oropharyngeal cancer (OPC). This study investigated the relationships between tumor volume and 18F-FDG-PET parameters before and during definitive radiotherapy with treatment outcomes. Methods and Materials Patients undergoing definitive (chemo)radiation for HPV-related/p16-positive OPC were prospectively enrolled on an IRB-approved study. 18F-FDG-PET/CT scans were performed at simulation and after 2 weeks at a dose of ∼20 Gy. Tumor volume and standardized uptake value (SUV) characteristics were measured. SUV was normalized to blood pool uptake. Tumor volume and PET parameters associated with recurrence were identified through recursive partitioning (RPART). Recurrence-free survival (RFS) and overall survival (OS) curves between RPART-identified cohorts were estimated using the Kaplan-Meier method and Cox models were used to estimate the hazard ratios (HR). Results From 2012 to 2016, 62 patients with HPV-related OPC were enrolled. Median follow-up was 4.4 years. RPART identified patients with intra-treatment SUVmax (normalized to blood pool SUVmean) > 6.7 with intra-treatment SUV40% > 2.75 as less likely to recur. For identified subgroups, results of Cox models showed unadjusted HR for RFS and OS (more likely to recur vs less likely) of 7.33 (90% CI 2.97 – 18.12) and 6.09 (90% CI 2.22 – 16.71), respectively and adjusted HR of 6.57 (90% CI 2.53 – 17.05) and 5.61 (90% CI 1.90 – 16.54) for RFS and OS, respectively. Conclusions PET parameters after 2 weeks of definitive radiotherapy for HPV-related OPC are associated with RFS and OS, thus potentially informing an adaptive treatment approach.

Background Drug-induced cardiomyopathy is a significant medical problem. Clinical diagnosis of myocardial injury is based on initial electrocardiogram, levels of circulating biomarkers, and perfusion imaging with single photon emission computed tomography (SPECT). Positron emission tomography (PET) is an alternative imaging modality that provides better resolution and sensitivity than SPECT, improves diagnostic accuracy, and allows therapeutic monitoring. The objective of this study was to assess the detection of drug-induced cardiomyopathy by PET using 2-deoxy-2-[18F]fluoro-D-glucose (FDG) and compare it with the conventional SPECT technique with [99mTc]-Sestamibi (MIBI). Methods Cardiomyopathy was induced in Sprague Dawley rats using high-dose isoproterenol. Nuclear [18F]FDG/PET and [99mTc]MIBI/SPECT were performed before and after isoproterenol administration. [18F]FDG (0.1 mCi, 200-400 µL) and [99mTc]MIBI (2 mCi, 200-600 µL) were administered via the tail vein and imaging was performed 1 hour postinjection. Isoproterenol-induced injury was confirmed by the plasma level of cardiac troponin and triphenyltetrazolium chloride (TTC) staining. Results Isoproterenol administration resulted in an increase in circulating cardiac troponin I and showed histologic damage in the myocardium. Visually, preisoproterenol and postisoproterenol images showed alterations in cardiac accumulation of [18F]FDG, but not of [99mTc]MIBI. Image analysis revealed that myocardial uptake of [18F]FDG reduced by 60% after isoproterenol treatment, whereas that of [99mTc]MIBI decreased by 45%. Conclusion We conclude that [18F]FDG is a more sensitive radiotracer than [99mTc]MIBI for imaging of drug-induced cardiomyopathy. We theorize that isoproterenol-induced cardiomyopathy impacts cellular metabolism more than perfusion, which results in more substantial changes in [18F]FDG uptake than in [99mTc]MIBI accumulation in cardiac tissue.

Knowledge of the intrinsic variability of radiomic features is essential to the proper interpretation of changes in these features over time. The primary aim of this study was to assess the test–retest repeatability of radiomic features extracted from 18F-FDG PET images of cervical tumors. The impact of different image preprocessing methods was also explored. Methods: Patients with cervical cancer underwent baseline and repeat 18F-FDG PET/CT imaging within 7 d. PET images were reconstructed using 2 methods: ordered-subset expectation maximization (PETOSEM) or ordered-subset expectation maximization with point-spread function (PETPSF). Tumors were segmented to produce whole-tumor volumes of interest (VOIWT) and 40% isocontours (VOI40). Voxels were either left at the default size or resampled to 3-mm isotropic voxels. SUV was discretized to a fixed number of bins (32, 64, or 128). Radiomic features were extracted from both VOIs, and repeatability was then assessed using the Lin concordance correlation coefficient (CCC). Results: Eleven patients were enrolled and completed the test–retest PET/CT imaging protocol. Shape, neighborhood gray-level difference matrix, and gray-level cooccurrence matrix features were repeatable, with a mean CCC value of 0.81. Radiomic features extracted from PETOSEM images showed significantly better repeatability than features extracted from PETPSF images (P 0.96) when extracted from VOI40. Conclusion: Shape, gray-level cooccurrence matrix, and neighborhood gray-level difference matrix radiomic features were consistently repeatable, whereas gray-level run length matrix and gray-level zone length matrix features were highly variable. Radiomic features extracted from VOI40 were more repeatable than features extracted from VOIWT. Changes in voxel size or SUV discretization parameters typically resulted in relatively small differences in feature value, though several features were highly sensitive to these changes.

International audience; PET/MRI with 18F-FDG has demonstrated the advantages of simultaneous PET and MR imaging in head and neck cancer imaging, MRI allowing excellent soft-tissue contrast, while PET provides metabolic information. The aim of this study was to evaluate the added value of gadolinium contrast-enhanced sequences in the tumor delineation of head and neck cancers on 18F-FDG-PET/MR imaging.

Objectives The aim of the study was to evaluate preliminary feasibility of 18F-FDG-PET/MRI in differentiation of pancreatic serous cystic neoplasms (SCNs) from non-SCNs. Methods From August 2017 to June 2019, 10 patients (3 men, 7 women; mean age, 63 years) previously diagnosed with pancreatic cystic neoplasm underwent simultaneous 18F-FDG-PET/MRI prospectively on an integrated 3-Tesla hybrid PET/MRI scanner. PET images were analyzed visually and semiquantitatively measuring standardized uptake values (SUV) including lesion SUVmax and SUVmean, lesion to pancreas and lesion to liver SUVmax and SUVmean ratio independent of MRI diagnosis. The reference standard for lesion diagnosis was by MRI features and interval follow-up. Results Visual assessment of PET images demonstrated uptake in 57% of SCNs. Lesion to liver SUVmax ratio of ≥0.5 showed the highest accuracy (90%) and area under the curve (0.9) followed by lesion SUVmax of ≥1.6 and lesion to pancreas SUVmax ratio of ≥0.77 for diagnosis of SCN. The sensitivity for lesion SUVmax of ≥1.6 was less than two other ones (71 versus 100%). All non-SCNs exhibited SUVmax value less than 1.6 while 33 and 66% demonstrated lesion to liver SUVmax ratio of >0.5 and lesion to pancreas SUVmax ratio of >0.77, respectively. PET/MRI specificity was 67, 100, 67 and 33% through lesion to liver SUVmax ratio, lesion SUVmax, lesion SUVmean and lesion to pancreas SUVmax ratio, respectively, for diagnosis of SCN. Conclusion Preliminary results show that PET/MRI utilization is promising for differentiation of pancreatic SCN from non-SCN lesions. This could reduce need for surveillance imaging or avoidance of unnecessary intervention in pancreatic cystic neoplasms with uncertain diagnoses.

Rationale: The present study aims to optimize injected dose of 18F-FDG in whole body PET/CT scan and assess its effect on Noise Equivalent count rate (NECR) and visual image quality (IQ) assessment. Methods: Patients scheduled to undergo 18F-FDG PET/CT were prospectively recruited in the study from January to December 2019, regardless of the indication/underlying disease. Patients were divided into four groups and injected different amounts of 18F-FDG radioactivity/kg body weight (1.85 MBq/kg, 3.7 MBq/kg, 5.5 MBq/kg and 7.4 MBq/kg). All patients underwent 18F-FDG PET/CT studies and NECRlocal was calculated by noting the trues rate, total prompts and randoms rate for each bed position. Whole body NECRglobal was calculated as average of NECR for all bed positions. Qualitative IQ assessment was done for each bed-position (IQlocal) and for whole-body PET (IQglobal) by two readers using 5-point scores based on prevalence of noise, contrast and lesion detectability. Values of NECR and IQ in all four activity groups were compared. Patients were also subdivided into four body mass index (BMI) groups [group I-15-20(kg/m2), group II-20.1-25 (kg/m2), group III-25.1-30 (kg/m2) and group IV-30.1-35 (kg/m2)] for comparison. A p value

Haploidentical hematopoietic stem cell transplantation followed by post‐transplant cyclophosphamide provides a well‐tolerated and potentially curable treatment for chemorefractory acute‐type adult T‐cell leukemia/lymphoma.

INTRODUCTION To correlate tumour grading and prognostic immunohistochemical markers of lung cancer with simultaneously acquired standardised uptake values (SUV) and apparent diffusion coefficient (ADC) derived from hybrid PET/MRI. METHODS In this retrospective study, 55 consecutive patients (mean age 62.5 ± 9.2 years) with therapy-naive, histologically proven lung cancer were included. All patients underwent whole-body PET/MRI using 18F-flourdeoxyglucose (18F-FDG) as a radiotracer. Diffusion-weighted imaging of the chest (DWI, b-values: 0, 500, 1000 s/mm2 ) was performed simultaneously with PET acquisition. Histopathological tumour grading was available in 43/55 patients. In 15/55 patients, immunohistochemical markers, that is, phospho-AKT Ser473 (pAKTS473), phosphorylated extracellular signal-regulated kinase (pERK), phosphatase and tensin homolog (PTEN), and human epidermal growth factor receptor 2 (erbB2) were available. RESULTS The average SUVmax, SUVmean, ADCmin and ADCmean in lung cancer primaries were 12.6 ± 5.9, 7.7 ± 4.6, 569.9 ± 96.1 s/mm2 and 825.8 ± 93.2 s/mm2 , respectively. We found a significant inverse correlation between the ADCmin and SUVmax (r = -0.58, P

We report our PET/MRI experience from a pilot study that compared the diagnostic performance of 18F-FDG PET/MRI versus PET/CT in staging of cervical cancer. Methods: Six adults with newly diagnosed cervical cancer underwent a single 18F-FDG injection with a dual-imaging protocol: standard-of-care PET/CT followed by research PET/MRI. The diagnostic interpretation and SUVmax for the 2 modalities were compared. Results: Both modalities detected all primary tumors (median size, 3.9 cm) and all 4 metastases present in 2 of the 6 patients (median size, 0.9 cm). PET/MRI provided greater diagnostic confidence than PET/CT and upstaged the disease in 4 patients. On the basis of the imaging findings alone, the additional information from PET/MRI would have led to a change in clinical management in 3 of 6 patients. The primary lesion showed a median SUV of 12.8 on PET/CT and 18.2 on PET/MRI (P = 0.03). SUVs, however, correlated strongly between the 2 modalities (ρ = 0.96, P

The aim of this study was to investigate the value of multiple parameters retrieved from the FDG PET/CT studies, including SUVmax, SUVmean, SUVpeak, MTV, TLG, tumour size in differentiating retroperitoneal paragangliomas from UCD. 28 patients with solitary retroperitoneal masses who had undergone preoperative 18F-FDG PET/CT were retrospectively evaluated. Histopathology by surgical resection confirmed 17 paragangliomas and 11 UCDs. SUVmax, SUVmean, SUVpeak, MTV, TLG, and tumour size of 18F-FDG PET/CT were measured for each patient. Mann–Whitney U-test was used to assess differences in multiple parameters between paragangliomas and UCDs. The ROC curve analysis was performed to determine the differential diagnostic value of these parameters. Paragangliomas presented significantly higher SUVmax (P P = 0.001), SUVpeak (P P = 0.024) than UCDs, whereas no significant difference was observed in MTV. The AUCs for differentiating paragangliomas and UCDs were 0.920, 0.888, 0.909, and 0.765 for SUVmax, SUVmean, SUVpeak, and TLG, respectively. The SUVmax cut-off of 7.75 yielded 82.4% sensitivity and 100% specificity for predicting paragangliomas. This study indicated that 18F FDG PET/CT-derived multiple metabolic parameters are useful in distinguishing between paragangliomas and UCDs. SUVmax showed the best result for the differential diagnosis of these two diseases among multiple metabolic parameters.

Background The metabolic behavior of plasmacytoma at 18F-FDG PET/CT is not yet clear. Objective The aim of this systematic review was to analyze published data about the role of 18F-FDG PET or PET/CT in patients affected by plasmacytoma. Methods A comprehensive computer literature search of the Scopus, PubMed/MEDLINE, Embase and Cochrane library databases was conducted including articles up to July 2019 to find relevant published papers about the performance of 18F-FDG PET and PET/CT in plasmacytoma. Results The comprehensive computer literature search revealed 371 articles. On reviewing the titles and abstracts, 363 articles were excluded because the reported data were not within the field of interest of this review. Eight articles were selected and retrieved in full-text version. From the analyses of the selected studies, the following main findings have been founded: 1) plasmacytoma generally is a 18F-FDG-avid tumor and PET/CT had good diagnostic performance with high sensitivity; 2) 18F-FDG PET/CT influenced patient management in most cases avoiding useless therapies and choosing the best therapeutic approach; 3) prognostic value of PET/CT qualitative and semiquantitative parameters is only suggested with controversial reports. Conclusion Despite several limitations affect this analysis, especially related to the low number of articles and patients studied, plasmacytoma looks to be an 18F-FDG-avid tumor in most of the cases; 18F-FDG PET or PET/CT had good diagnostic performance and had a significant clinical impact in change of therapeutic approach. Moreover, a possible prognostic role of PET/CT features is described.

Objective The liver is the most frequent metastatic site from colorectal cancer and about 20% of these patients are treated by surgical resection. However, the 5-year disease-free survival (DFS) following resection is only about 25% and 5-year overall survival (OS) about 38%. The aim of the study was to evaluate the ability of metabolic and volumetric measurements from fluorine-18-fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) prior to resection for colorectal liver metastases (CLM) to predict survival. Patients and methods Preoperative F-FDG PET/CT examinations were assessed. Metabolic tumor volume (MTV), total lesion glycolysis (TLG), maximum, mean and peak standardized uptake values and tumor to background ratio, were obtained for all CLM. Cutoff values were determined for each of these parameters by using receiver operating characteristic analysis dividing the patients into two groups. DFS, liver recurrence-free survival (LRFS), OS and cancer-specific survival (CSS) for patients over and under the cutoff value were compared by using the Kaplan-Meier method and log-rank test. Results Twenty-seven patients who underwent F-FDG PET/CT prior to resection for CLM were included. Low values of total MTV and TLG were significantly correlated to improved 5-year LRFS (P = 0.016 and 0.006) and CSS (P = 0.034 and 0.008). Patients who developed liver recurrence had significantly higher total MTV and TLG compared to patients without liver recurrence (P = 0.042 and 0.047). Conclusion Low values of total MTV and TLG were significantly correlated to improved LRFS and CSS and may improve the risk stratification of patients considered for resection for CLM.

Initial studies of tuberculosis (TB) in macaques and humans using 18F-FDG positron emission tomography (PET) imaging as a research tool suggest its usefulness in localising disease sites and as a clinical biomarker. Sequential serial scans in patients with extrapulmonary TB (EPTB) could inform on the value of PET-CT for monitoring response to treatment and defining cure. HIV-negative adults with EPTB from eight sites across six countries had three 18F-FDG PET/CT scans: (i) within 2 weeks of enrolment, (ii) at 2 months into TB treatment and (iii) at end of ATT treatment. Scanning was performed according to the EANM guidelines. 18F-FDG PET/CT scans were performed 60 ± 10 min after intravenous injection of 2.5–5.0 MBq/kg of 18F-FDG. One hundred and forty-seven patients with EPTB underwent 3 sequential scans. A progressive reduction over time of both the number of active sites and the uptake level (SUVmax) at these sites was seen. At the end of WHO recommended treatment, 53/147 (36.0%) patients had negative PET/CT scans, and 94/147 (63.9%) patients remained PET/CT positive, of which 12 patients had developed MDR TB. One died of brain tuberculoma. Current 18F-FDG PET/CT imaging technology cannot be used clinically as a biomarker of treatment response, cure or for decision-making on when to stop EPTB treatment. PET/CT remains a research tool for TB and further development of PET/CT is required using new Mycobacterium tuberculosis-specific radiopharmaceuticals targeting high-density surface epitopes, gene targets or metabolic pathways.

To identify an 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) radiomics-based model for predicting progression-free survival (PFS) and overall survival (OS) of nasal-type extranodal natural killer/T cell lymphoma (ENKTL). In this retrospective study, a total of 110 ENKTL patients were divided into a training cohort (n = 82) and a validation cohort (n = 28). Forty-one features were extracted from pretreatment PET images of the patients. Least absolute shrinkage and selection operator (LASSO) regression was used to develop the radiomic signatures (R-signatures). A radiomics-based model was built and validated in the two cohorts and compared with a metabolism-based model. The R-signatures were constructed with moderate predictive ability in the training and validation cohorts (R-signaturePFS: AUC = 0.788 and 0.473; R-signatureOS: AUC = 0.637 and 0.730). For PFS, the radiomics-based model showed better discrimination than the metabolism-based model in the training cohort (C-index = 0.811 vs. 0.751) but poorer discrimination in the validation cohort (C-index = 0.588 vs. 0.693). The calibration of the radiomics-based model was poorer than that of the metabolism-based model (training cohort: p = 0.415 vs. 0.428, validation cohort: p = 0.228 vs. 0.652). For OS, the performance of the radiomics-based model was poorer (training cohort: C-index = 0.818 vs. 0.828, p = 0.853 vs. 0.885; validation cohort: C-index = 0.628 vs. 0.753, p

Background Attenuation correction (AC) of PET data is usually performed using a second imaging for the generation of attenuation maps. In certain situations however—when CT- or MR-derived attenuation maps are corrupted or CT acquisition solely for the purpose of AC shall be avoided—it would be of value to have the possibility of obtaining attenuation maps only based on PET information. The purpose of this study was to thus develop, implement, and evaluate a deep learning-based method for whole body [18F]FDG-PET AC which is independent of other imaging modalities for acquiring the attenuation map. Methods The proposed method is investigated on whole body [18F]FDG-PET data using a Generative Adversarial Networks (GAN) deep learning framework. It is trained to generate pseudo CT images (CTGAN) based on paired training data of non-attenuation corrected PET data (PETNAC) and corresponding CT data. Generated pseudo CTs are then used for subsequent PET AC. One hundred data sets of whole body PETNAC and corresponding CT were used for training. Twenty-five PET/CT examinations were used as test data sets (not included in training). On these test data sets, AC of PET was performed using the acquired CT as well as CTGAN resulting in the corresponding PET data sets PETAC and PETGAN. CTGAN and PETGAN were evaluated qualitatively by visual inspection and by visual analysis of color-coded difference maps. Quantitative analysis was performed by comparison of organ and lesion SUVs between PETAC and PETGAN. Results Qualitative analysis revealed no major SUV deviations on PETGAN for most anatomic regions; visually detectable deviations were mainly observed along the diaphragm and the lung border. Quantitative analysis revealed mean percent deviations of SUVs on PETGAN of − 0.8 ± 8.6% over all organs (range [− 30.7%, + 27.1%]). Mean lesion SUVs showed a mean deviation of 0.9 ± 9.2% (range [− 19.6%, + 29.2%]). Conclusion Independent AC of whole body [18F]FDG-PET is feasible using the proposed deep learning approach yielding satisfactory PET quantification accuracy. Further clinical validation is necessary prior to implementation in clinical routine applications.

Background and purpose To investigate potential image markers for early prediction of treatment response on thoracic esophagus squamous cell carcinoma (ESCC) treated with concurrent chemoradiotherapy (CCRT). Materials and methods 159 thoracic ESCC patients enrolled from two institutions were divided into training and validation sets. A total of 944 radiomics features were extracted from pretreatment 18F-FDG PET images. We first performed the inter-observer reproducibility test in 10 pairs of patients (responders vs. nonresponders), and the limma package was used to identify differentially expressed features (DEFs). Then the least absolute shrinkage and selection operator (LASSO) logistic regression model with 10-fold cross-validation was used to construct a treatment response related radiomics signature. Finally, the performance was assessed in both sets with receiver operating characteristic (ROC) curves and Kaplan-Meier analysis. Results After the inter-observer test, 691 features were considered reproducible and been retained (ICC > 0.9). 61 DEFs were selected from limma and entered into the LASSO logistic regression model. The radiomics signature was significantly associated with treatment response in the training (p Conclusion This study indicated that the proposed radiomics signature could be a useful image marker to predict the therapeutic response of thoracic ESCC patients treated with CCRT.

Biomedical data frequently contain imbalance characteristics which make achieving good predictive performance with data-driven machine learning approaches a challenging task. In this study, we investigated the impact of re-sampling techniques for imbalanced datasets in PET radiomics-based prognostication model in head and neck (HNC) cancer patients. Radiomics analysis was performed in two cohorts of patients, including 166 patients newly diagnosed with nasopharyngeal carcinoma (NPC) in our centre and 182 HNC patients from open database. Conventional PET parameters and robust radiomics features were extracted for correlation analysis of the overall survival (OS) and disease progression-free survival (DFS). We investigated a cross-combination of 10 re-sampling methods (oversampling, undersampling, and hybrid sampling) with 4 machine learning classifiers for survival prediction. Diagnostic performance was assessed in hold-out test sets. Statistical differences were analysed using Monte Carlo cross-validations by post hoc Nemenyi analysis. Oversampling techniques like ADASYN and SMOTE could improve prediction performance in terms of G-mean and F-measures in minority class, without significant loss of F-measures in majority class. We identified optimal PET radiomics-based prediction model of OS (AUC of 0.82, G-mean of 0.77) for our NPC cohort. Similar findings that oversampling techniques improved the prediction performance were seen when this was tested on an external dataset indicating generalisability. Our study showed a significant positive impact on the prediction performance in imbalanced datasets by applying re-sampling techniques. We have created an open-source solution for automated calculations and comparisons of multiple re-sampling techniques and machine learning classifiers for easy replication in future studies.

Periprosthetic joint infection (PJI) is a severe complication, associated with substantial morbidity and high costs. PJI can occur in the early postoperative period but also many years after joint replacement. Timely and accurate diagnosis is important for treatment planning. Diagnosis of PJI can be a challenge, especially for chronic and low-grade infections. The diagnostic performance of fludeoxyglucose F 18 (18F-FDG) positron emission tomography (PET) in detecting PJI seems sufficiently high for routine clinical application and has additional value to conventional tests. Further research is needed to determine the exact place of 18F-FDG PET in the diagnostic work-up of suspected PJI.