Diagnostic Performance and Interobserver Agreement of Diuretic 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in the Diagnosis of Upper Urinary Tract Cancer.

BACKGROUND: Previous reports attempted to evaluate bladder cancer using 18 F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) by washing out the excreted FDG with a diuretic. The purpose of this study was to evaluate the value of diuretic FDG PET/plain CT (drtPET/CT) and diuretic FDG PET/contrast-enhanced CT (drtPET/ceCT) in the assessment of upper urinary tract cancers. MATERIALS AND METHODS: A total of 66 patients underwent drtPET/CT for suspected upper urinary tract cancer (UUTC). The study targeted 29 patients who were strongly suspected of having UUTC and underwent magnetic resonance imaging (MRI) of the upper urinary tract. A total of 29 (24 male, five female) patients, with a mean ± SD age of 73 ± 3 (range, 43-84) years, had a suspected neoplasm in the upper urinary tract. They underwent FDG PET/plain and contrast-enhanced CT before and after a diuretic and MRI including diffusion-weighted imaging (DWI). A urologist and a physician board-certified in nuclear medicine and radiology independently interpreted the standard PET/CT (stdPET/CT), drtPET/CT, drtPET/ceCT, ceCT, and MRI with DWI images. Interobserver agreement and the diagnostic performance of each modality were evaluated. RESULTS: The kappa values of stdPET/CT, drtPET/CT, drtPET/ceCT, ceCT, and MRI were 0.381, 0.567, 0.7031, 0.448, and 0.185, respectively, with drtPET/ceCT showing the highest kappa value and the only one with good interobserver agreement (>60%). The area under the curve of drtPET/ceCT was 0.92, which was significantly higher than those of stdPET/CT (P=0.027) and MRI (P=0.047). CONCLUSIONS: In the present study, drtPET/ceCT had the best diagnostic performance and the highest interobserver agreement for detecting upper urinary tract urothelial cancers.

Impacts of 18F-FDG PET/CT Parameters on Differential Diagnosis and Outcome of Patients with Primary Invasive Mucinous and Lepidic Predominant Adenocarcinoma of the Lung.

Objectives: The purpose of this study was to investigate whether 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) parameters have a role in differentiating invasive mucinous lung adenocarcinoma (IMA) from lepidic predominant lung adenocarcinoma (LPA). Additionally, we compared the 18F-FDG-PET/CT features between survivors and non-survivors. Methods: Tumors were divided into 2 groups according to CT appearance: Group 1: nodular-type tumor; group 2: mass- or pneumonic-type tumor. Unilateral and bilateral multifocal diseases were detected. Clinicopathological characteristics and PET/CT findings were compared between IMAs and LPAs, as well as between survivors and non-survivors. Results: We included 43 patients with IMA and 14 with LPA. Tumor size (p=0.003), incidence of mass/pneumonic type (p=0.011), and bilateral lung involvement (p=0.049) were higher in IMAs than in LPAs. IMAs had more advanced T, M, and Tumor, Node, and Metastasis stages than in LPAs (p=0.048, p=0.049, and p=0.022, respectively). There was no statistically significant difference in maximum standardized uptake value (SUVmax) between the IMA and LPA (p=0.078). The SUV was significantly lower in the nodular group than in the mass/pneumonic-type group (p=0.0001). A total of 11 patients died, of whom SUVmax values were significantly higher in these patients (p=0.031). Male gender (p=0.0001), rate of stage III-IV (p=0.0001), T3-T4 (p=0.021), M1 stages (p=0.0001), multifocality (p=0.0001), and bilateral lung involvement (p=0.0001) were higher in non-survivor. Conclusions: Although CT images were useful for the differential diagnosis of LPAs and IMAs, SUVmax was not helpful for differentiation of these 2 groups. However, both 18F-FDG uptake and CT findings may play an important role in predicting prognosis in these patients.

Prognostic Importance of 18F-FDG Positron Emission Tomography in Uterine Cervical Cancer.

Objectives: The aim of this study was to evaluate the prognostic value of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in the uterine cervix cancer patients. Methods: Thirty-two women (mean age: 52.7±12.6) who underwent 18F-FDG PET/CT for staging of uterine cervix cancer were retrospectively recruited for the study. Maximum standardized uptake value (SUVmax), SUVmean, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for primary tumors, lymph nodes, and distant metastases were calculated from 18F-FDG PET/CT images using the 40% threshold. Patients were divided into groups according to the presence of pelvic and para-aortic lymph node involvement on 18F-FDG PET/CT images. Life tables and Kaplan-Meier analyses were performed to compare the mean survival times of the different groups. Results: Primary tumor of 27 (84%) patients were 18F-FDG avid. The median SUVmax, SUVmean, MTV, and TLG of the primary tumors were 12.4, 6.1, 13.2 cm3 and 87.8 g/mL x cm3 respectively. Pathological uptake was detected in pelvic 14 (44%) patients and in paraaortic lymph nodes in 3 (10%) para-aortic lymph nodes. The median whole-body MTV and TLG were 21.7 cm3 and 91.1 g/mL x cm3. Disease progression was detected in 7 (22%) patients within a median follow-up period of 20.9 (minimum-maximum: 3-82) months. The only significant PET parameter to predict progression-free survival was SUVmax in the primary tumor (p=0.038). During follow-up period 8 patients died. SUVmax (p=0.007), MTV (p=0.036), TLG (p=0.001) of primary tumor, presence of pathological uptake on pelvic or paraaortic lymph nodes (p=0.015), whole-body MTV (p=0.047) and whole-body TLG (p=0.001) were found statistically significant PET parameters to predict overall survival. Conclusion: Metabolic parameters of primary tumors derived from 18F-FDG PET/CT images have prognostic importance for patients with uterine cervical carcinoma. In patients with metastatic disease, higher whole-body MTV and TLG are also associated with poor prognosis.

An Unusual Case of Oligometastases in a Patient with Renal Cell Carcinoma: Insights from 18F-FDG PET/CT.

Renal cell carcinoma (RCC) is a significant cause of mortality worldwide. To date, many atypical metastatic sites have been observed and reported in patients with RCC. However, to the best of our knowledge, there have been no reported cases of thyroid cartilage metastasis in the context of RCC metastasis. Herein, we present the case of a 68-year-old man who developed left arm pain that led to an RCC diagnosis. First, evaluation by pan-computed tomography (CT) denoted right kidney RCC and identified left humeral metastasis. Subsequently, 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT) was performed after right nephrectomy and left humeral lesion excision and fixation. Interestingly, few intramedullary hypermetabolic lesions were observed in addition to a single intensely hypermetabolic thyroid cartilage lesion indicative of oligometastases. This case underscores the importance of 18F-FDG PET/CT in the evaluation of RCC disease for baseline staging and beyond.

18F-FDG PET/CT and 68Ga-DOTATATE PET/CT Findings of Polycystic Kidney-derived Paraganglioma.

Paragangliomas (PGLs) are neuroendocrine tumors originating from the neural crest. They usually arise from the adrenal medulla and sympathetic or parasympathetic ganglions. Approximately 10% of PGLs are located in the extra-adrenal gland. Renal PGL is a rare condition. In this case report, we present the 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) and 68Ga-DOTATATE PET/CT findings of polycystic kidney-derived PGL.

Bone Marrow Necrosis with Underlying Skeletal Lymphoma Evaluated by 18F-FDG PET/CT and MRI.

Bone marrow necrosis (BMN) is usually associated with malignancies and is characterized by multiple geographic signal abnormalities on magnetic resonance imaging (MRI). We report a 28-year-old female with BMN and underlying diffuse large B-cell lymphoma. Diffuse abnormal signal intensities through the vertebral column were demonstrated on her pretreatment MRI, and the diagnosis of BMN was challenging. Positron emission tomography/computed tomography (PET/CT) for lymphoma staging showed multiple decreased or absent 18F-fluorodeoxyglucose (18F-FDG) uptake within the vertebrae and pelvis. Marrow biopsy pathological examination showed lymphoma infiltration and massive necrosis. On the follow-up MRI obtained approximately 21 months after the PET/CT scan, multiple geographic abnormal signal intensities were detected within the vertebral column and were consistent with the areas of decreased 18F-FDG uptake on PET/CT. This case indicates that 18F-FDG PET/CT is helpful in the diagnosis of BMN with atypical MRI appearances.

Multiple Bone Involvement in Low-grade Myofibroblastic Sarcoma Demonstrated on 18F-FDG PET/CT.

A 68-year-old woman with low back pain for 2 months was admitted. T2-weighted fat-saturated imaging revealed hyperintense lesions in multiple lumbar regions, suggesting the possibility of bone metastases. Multiple osteolytic and mixed osteolytic-osteoblastic lesions with significant 18F-fluorodeoxyglucose (18F-FDG) uptake, as well as multiple osteoblastic lesions with mild 18F-FDG uptake, were observed on subsequent 18F-FDG positron emission tomography/computed tomography without an identifiable primary lesion. This patient was pathologically diagnosed with low-grade myofibroblastic sarcoma (LGMS) after biopsy and surgery. Although multiple bone involvement in LGMS is extremely rare, this case suggests that it should be considered in the differential diagnosis of multiple bone metastases.

Pre-treatment [18F]FDG PET/CT biomarkers for the prediction of antibody-drug conjugates efficacy in metastatic breast cancer.

PURPOSE: This study aimed to evaluate the association between pretreatment [18F]FDG PET/CT-derived biomarkers and outcomes in metastatic breast cancer (mBC) patients treated with antibody-drug conjugates (ADCs) Sacituzumab Govitecan (SG) and Trastuzumab Deruxtecan (T-DXd). METHODS: A retrospective bicentric analysis was conducted on triple-negative mBC (mTNBC) patients treated with SG and HER2-low mBC patients treated with T-DXd, who underwent [18F]FDG PET/CT scans before therapy. Key biomarkers, including maximum standardized uptake value (SUVmax), total metabolic tumor volume (TMTV) and maximum tumor dissemination (Dmax), were measured. Their prognostic value for progression-free survival (PFS) and overall survival (OS) was assessed using Cox models and Kaplan-Meier curves. RESULTS: 128 patients were included: 71 mTNBC treated with SG and 57 HR-positive and -negative HER2-low mBC treated with T-DXd. Median follow-up was 12.9 months. In the SG cohort, median PFS and OS were 4.8 and 8.9 months, respectively. High Dmax (HR 2.1, 95% CI 1.1-4.3) and high TMTV (HR 2.9, 95% CI 1.2-6.6) were independently associated with shorter OS. In the T-DXd cohort, median PFS and OS were 5.8 and 9.0 months, respectively. High Dmax (HR 2.1, 95% CI 1.2-3.9) and high TMTV (HR 2.4, 95% CI 1.0-6.5) independently correlated with shorter PFS and shorter OS, respectively. CONCLUSION: Pretreatment [18F]FDG PET/CT-derived biomarkers, namely TMTV and Dmax, have significant prognostic value in patients with mTNBC and HER2-low mBC treated with SG and T-DXd. These biomarkers improve prognostic prediction and may optimize treatment strategies, warranting their clinical use, but larger studies are needed to validate these findings.

Enhancing Lymphoma Diagnosis, Treatment, and Follow-Up Using 18F-FDG PET/CT Imaging: Contribution of Artificial Intelligence and Radiomics Analysis.

Lymphoma, encompassing a wide spectrum of immune system malignancies, presents significant complexities in its early detection, management, and prognosis assessment since it can mimic post-infectious/inflammatory diseases. The heterogeneous nature of lymphoma makes it challenging to definitively pinpoint valuable biomarkers for predicting tumor biology and selecting the most effective treatment strategies. Although molecular imaging modalities, such as positron emission tomography/computed tomography (PET/CT), specifically 18F-FDG PET/CT, hold significant importance in the diagnosis of lymphoma, prognostication, and assessment of treatment response, they still face significant challenges. Over the past few years, radiomics and artificial intelligence (AI) have surfaced as valuable tools for detecting subtle features within medical images that may not be easily discerned by visual assessment. The rapid expansion of AI and its application in medicine/radiomics is opening up new opportunities in the nuclear medicine field. Radiomics and AI capabilities seem to hold promise across various clinical scenarios related to lymphoma. Nevertheless, the need for more extensive prospective trials is evident to substantiate their reliability and standardize their applications. This review aims to provide a comprehensive perspective on the current literature regarding the application of AI and radiomics applied/extracted on/from 18F-FDG PET/CT in the management of lymphoma patients.

Establishing a predictive model for tumor mutation burden status based on 18F-FDG PET/CT and clinical features of non-small cell lung cancer patients.

Background: Tumor mutation burden (TMB) has emerged as a promising biomarker for immune checkpoint inhibitors (ICI) response, but its detection through whole exome sequencing (WES) is costly and invasive. This study aims to establish a predictive model for TMB using baseline metabolic parameters (MPs) of 18F-fluorodeoxyglucose (FDG) uptake on positron emission tomography/computed tomography (PET/CT) and clinical features in non-small cell lung cancer (NSCLC) patients, potentially offering a non-invasive and cost-effective method to predict TMB status. Methods: A total of 223 NSCLC patients with baseline 18F-FDG PET/CT scans and TMB detection results were retrospectively enrolled from January 2019 to September 2023, and were divided into two groups: TMB-high (≥4 mutations/Mb, 96 patients) and TMB-low (<4 mutations/Mb, 127 patients). Twelve clinical features and five PET parameters were assessed. Univariate analysis was conducted in all patients to reveal the preliminary associations between variables and TMB status. All patients were randomly divided into a training set (n=135) and a validation set (n=88). Feature selection was performed using lasso regression and logistic regression analyses. A predictive model and nomogram were established with the features selected above. Decision curve analysis (DCA) was performed to assess the clinical utility of the developed model. Results: Two clinical features and two PET parameters were identified through lasso regression and logistic regression analysis including pathology type, cancer antigen 125 (CA125) level, maximum standardized uptake value (SUVmax), and metabolic tumor volume (MTV). The predictive model exhibited an area under the curve (AUC) of 0.822 [95% confidence interval (CI), 0.751-0.894], and internal validation yielded an AUC of 0.822 (95% CI, 0.731-0.912). The model was well-calibrated. The developed nomogram, incorporating the four selected variables, showed promising potential in evaluating TMB status in NSCLC patients. Conclusions: In this study, a predictive model combining 18F-FDG PET/CT and clinical features of NSCLC patients effectively distinguished between TMB-high and TMB-low status. The nomogram generated from this model holds significant promise for predicting TMB status, offering valuable insights for clinical decision-making.

18F-FDG-PET/CT Scan for Detection of Large Vessel Involvement in Giant Cell Arteritis: Arteser Spanish Registry.

Background/Objectives: Imaging studies have transformed the diagnosis of large vessel vasculitis (LVV) involvement in giant cell arteritis (GCA). A positron emission tomography/computed tomography (PET/CT) scan with 18-fluorodeoxyglucose (18F-FDG) has emerged as a valuable tool for assessing LVV. We aimed to determine the utility of an 18F-FDG-PET/CT scan in detecting LVV in GCA in the ARTESER registry. Methods: The ARTESER study is a large multicenter, retrospective, longitudinal, and observational study, promoted by the Spanish Society of Rheumatology. It included patients newly diagnosed with GCA across 26 tertiary hospitals from 1 June 2013 to 29 March 2019. Patients with a diagnosis of incidental GCA were included if they fulfilled specific criteria, including the ACR 1990 criteria, positive imaging examinations, or the expert clinical opinion of investigators. Differences between patients with positive and negative 18F-FDG-PET/CT scan results were analyzed using a bivariate model. A regression model assessed associations in patients with a positive scan, and the predictive capacity of the cumulative dose of glucocorticoids (GC) on PET scan outcomes was evaluated using ROC curve analysis. Results: Out of 1675 GCA patients included in the registry, 377 met the inclusion criteria of having an 18F-FDG-PET/CT scan. The majority were diagnosed with a cranial GCA phenotype, and 65% had LVV. The thoracic aorta was the most frequently affected. Cardiovascular disease, diabetes, and older age had a negative association with a positive scan outcome. The OR for having a positive 18F-FDG-PET/CTC scan was lower as the number of days increased. Depending on the cumulative dosage of the GC, the 18F-FDG-PET/CT scan showed an AUC of 0.74, with a Youden index > 60 mg/day. Conclusions: Younger patients showed a higher probability of presenting LVV as detected by the 18F-FDG-PET/CT scan. The timing of the examination and the cumulative dosage of the GC influenced the likelihood of a positive result, with earlier tests being more likely to detect inflammation.

18F-FDG PET/CT impact in grade 3B follicular lymphoma.

[18F]-fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) is a non-invasive imaging tool that has a fundamental role in the management of FDG-avid lymphoma (also FL) in different settings, especially in the evaluation of treatment response and prognostication. The report by Barraclough et al. demonstrated that the treatment response evaluation by 18F-FDG PET/CT was a strong predictor of prognosis in grade 3B follicular lymphoma (G3BFL). Moreover, among semiquantitative baseline PET features, standardized uptake value (SUV) and TGL showed to be useful in predicting progression-free survival (PFS). Commentary on: Barraclough et al. The value of semiquantitative PET features and end-of-therapy PET in grade 3B follicular lymphoma. Br J Haematol 2024 (Online ahead of print). doi: 10.1111/bjh.19823.

Evaluating early response assessment in extranodal natural killer/T-cell lymphoma by analyzing ΔSUVlbm between baseline and interim 18F-FDG PET/CT scans.

To determine the optimal variation in SUVlbm via 18F-FDG PET/CT imaging between the baseline and interim stages, and assess early response among patients with extranodal natural killer/T-cell lymphoma (ENKTCL) of 5-DS score ≥ 4, 20 patients after four cycles of chemotherapy were retrospectively enrolled and received re-biopsy targeting PET-positive residual masses. The optimal cutoff value for evaluating early response assessment was 66.75% for ΔSUVlbm%, with the area under curve of 0.985. All patients with a 5-DS score of 4 exhibited negative results upon re-biopsy. During follow-up, the median PFS of patients characterized by ΔSUVlbm% ≥66.75% and <66.75% were unreached and 10 months, respectively. Utilizing ΔSUVlbm% between baseline and interim 18F-FDG PET/CT scans can effectively identify a subset of patients who were visually analyzed as false positives(5-DS ≥ 4), which was confirmed by interim biopsy results, thus serving as a crucial indicator for early assessment of treatment outcomes in patients with ENKTCL.

Baseline and interim 18F-FDG PET/CT metabolic parameters predict the efficacy and survival in patients with diffuse large B-cell lymphoma.

Introduction: The prognostic value of 18F-FDG PET/CT metabolic parameters, such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), in diffuse large B-cell lymphoma (DLBCL) remains inadequately explored. This study aims to assess the correlation between these parameters and patient outcomes. Methods: A cohort of 156 DLBCL patients underwent 18F-FDG PET/CT imaging at baseline and after 3-4 cycles of R-CHOP or CHOP-like regimen. The third quartiles of liver uptake values were used as thresholds for calculating MTV and TLG. Patient outcomes were analyzed based on Ann Arbor staging and the 5-PS score. A nomogram was developed to predict overall survival (OS). Results: Patients with low baseline TLG exhibited significantly better outcomes compared to those with high baseline TLG in both Ann Arbor stages I-II and III-IV (1-year PFS: 78.9% vs. 40%, p=0.016; OS: 94.7% vs. 40%, p=0.005 for stage I-II; 1-year PFS: 74.1% vs. 46.8%, p=0.014; OS: 85.4% vs. 71.8%, p=0.007 for stage III-IV). In interim PET/CT patients with a 5-PS score >3, the high ΔTLG group had superior prognosis (1-year PFS: 82.3% vs. 35.7%, p=0.003; OS: 88.2% vs. 85.7%, p=0.003). The nomogram achieved a C-index of 0.9 for OS prediction. Discussion: The findings suggest that baseline TLG is a robust prognostic indicator for patients with DLBCL, particularly in early stages, while ΔTLG effectively distinguishes those with favorable outcomes in higher-risk groups. These metabolic parameters from 18F-FDG PET/CT could enhance treatment decision-making and patient management strategies.

Transcatheter Aortic Valve-in-Valve Implantation in a Patient Due to the Degeneratation of the Biointegral Valve Conduit as a Result of Previous Infectious Endocarditis.

Graft infection, fistula, and mediastinitis are reported among the serious cardiovascular complications after a Bentall procedure. Surgery associated with antimicrobial treatment is usually recommended but not easily feasible in most cases. In this report, we describe a case of successful valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) in a patient with a degenerated bioconduit from a previously healed infectious endocarditis (IE). The TAVR procedure has been demonstrated to be a therapeutic option in selected cases with a previous history of IE who have been fully treated with antimicrobial therapy and who present a low risk of local re-infection and are deemed at prohibitive or high risk for surgical replacement. Data on TAVR on a bioconduit after a Bentall procedure are scarce. The present case underlines that a long follow-up and individualized treatment could improve the prognosis in patients with a history of prosthetic valve and aortic graft infection and severe valve dysfunction who cannot undergo surgical treatment. The 18F-labeled fluoro-2-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) result could be successfully employed in the decision algorithm. Long-term antibiotic treatment, which could be lifelong in some instances, could be a reasonable choice when the risk of recurrence is associated with the risk for the patient's life.

Deep-learning-derived input function in dynamic [18F]FDG PET imaging of mice.

Dynamic positron emission tomography and kinetic modeling play a critical role in tracer development research using small animals. Kinetic modeling from dynamic PET imaging requires accurate knowledge of an input function, ideally determined through arterial blood sampling. Arterial cannulation in mice, however, requires complex, time-consuming and terminal surgery, meaning that longitudinal studies are impossible. The aim of the current work was to develop and evaluate a non-invasive, deep-learning-based prediction model (DLIF) that directly takes the PET data as input to predict a usable input function. We first trained and evaluated the DLIF model on 68 [18F]Fluorodeoxyglucose mouse scans with image-derived targets using cross validation. Subsequently, we evaluated the performance of a trained DLIF model on an external dataset consisting of 8 mouse scans where the input function was measured by continuous arterial blood sampling. The results showed that the predicted DLIF and image-derived targets were similar, and the net influx rate constants following from Patlak modeling using DLIF as input function were strongly correlated to the corresponding values obtained using the image-derived input function. There were somewhat larger discrepancies when evaluating the model on the external dataset, which could be attributed to systematic differences in the experimental setup between the two datasets. In conclusion, our non-invasive DLIF prediction method may be a viable alternative to arterial blood sampling in small animal [18F]FDG imaging. With further validation, DLIF could overcome the need for arterial cannulation and allow fully quantitative and longitudinal experiments in PET imaging studies of mice.

Case Report: Application of 18F-FDG PET/CT in identifying plasmacytoma in monoclonal gammopathy associated peripheral neuropathy.

Peripheral neuropathy is a prevalent complication in plasma cell disorders, posing significant diagnostic and therapeutic challenges. This study presents three cases initially diagnosed with chronic inflammatory demyelinating polyneuropathy (CIDP). Despite initial symptom regression post-immunomodulatory treatment, the patients exhibited progressive neurological deficits. Advanced laboratory evaluation confirmed monoclonal protein presence, yet traditional diagnostic methods, including bone marrow biopsy and flow cytometry, yielded normal results. Utilizing 18F-FDG PET/CT, we identified multiple hypermetabolic vertebral lesions, which upon biopsy, confirmed the diagnosis of plasmacytoma. Our findings underscore the utility of PET/CT as a reliable diagnostic tool for monoclonal gammopathy associated neuropathy, advocating for its consideration in cases with equivocal diagnosis. When the diagnosis is in doubt, biopsy of a lesion may facilitate early and accurate diagnosis, potentially influencing treatment strategies and patient outcomes.

Prospective Comparison of [18F]FDG and [18F]AIF-FAPI-74 PET/CT in the Evaluation of Potentially Resectable Pancreatic Ductal Adenocarcinoma.

PURPOSE: Accurate clinical staging of potentially resectable pancreatic ductal adenocarcinoma (PDAC) is critical for establishing optimal treatment strategies. While the efficacy of fluorine-18-fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) in clinical staging is unclear, PET/CT detecting fibroblast-activation protein (FAP) expression has recently received considerable attention for detecting various tumors, including PDAC, with high sensitivity. We explored the efficacy of [18F]FDG and [18F]AIF-FAPI-74 PET/CT in the initial evaluation of potentially resectable PDAC. PROCEDURES: Between 2021 and 2022, twenty participants with newly diagnosed potentially resectable PDAC were enrolled. After the initial evaluation with pancreatic CT, [18F]FDG PET/CT, and [18F]AIF-FAPI-74 PET/CT, treatment strategies were determined considering the participant's general status, clinical staging, and resectability. Pathological information from the surgical specimens was only available in 17 participants who underwent curative-intent surgery. Head-to-head comparisons of quantitative radiotracer uptake and diagnostic performance were performed among imaging modalities. RESULTS: [18F]AIF-FAPI-74 PET/CT showed a significantly higher maximum standardized uptake value than [18F]FDG PET/CT did in evaluating primary pancreatic lesions (median [interquartile range]; 12.6 [10.7-13.7] vs. 6.3 [4.8-9.2]; P < 0.001). In contrast, [18F]AIF-FAPI-74 PET/CT showed a significantly lower mean standardized uptake value than [18F]FDG PET/CT did in evaluating background organ (median [interquartile range]) 0.8 [0.7-0.9] vs. 2.6 [2.3-2.7]; P < 0.001). In addition, the sensitivity of [18F]AIF-FAPI-74 PET/CT in detecting metastatic lymph nodes was higher than that of [18F]FDG PET/CT (50.0% vs. 0.0%; P = 0.026). CONCLUSION: This study demonstrated that [18F]AIF-FAPI-74 PET/CT could improve the clinical staging of potentially resectable PDAC.

Deciding treatment end point in necrotizing otitis externa: validation of a standardized clinical response assessment strategy with positron emission tomography findings.

OBJECTIVES: Primary: To explore criteria for treatment endpoint in NOE. Secondary: To study correlation of inflammatory markers, Erythrocyte sedimentation Rate (ESR) and C-reactive protein (CRP) with disease status. METHODS: Prospective cohort study conducted in a tertiary care hospital over two years (2021-2023) consisted 28 patients with NOE. Treatment culmination point was decided based on symptoms control and correlated with PET-scan findings. Clinical response was analysed with respect to the serum inflammatory markers and PET Scan findings. RESULTS: There was fair degree of agreement between clinical resolution and resolution of findings on PET scan (kappa coefficient - 0.76 [95% CI; 0.40,1.00]). Inflammatory markers showed statistically significant decline with clinical resolution but failed to return to normal. CONCLUSION: Decision to terminate treatment of NOE can be reliably made on clinical grounds in patients remaining asymptomatic for three weeks. Resolution of inflammation on PET scan is in congruity with the clinical remission .

Investigation of the distribution of inguinal lymph nodes and delineation of the inguinal clinical target volume using 18F-FDG PET/CT.

OBJECTIVE: Radiotherapy is a crucial treatment modality for pelvic cancers, but uncertainties persist in defining the clinical target volume (CTV) for the inguinal lymphatic drainage region. Suboptimal CTV delineation may compromise treatment efficacy and result in subpar disease control. This study aimed to investigate and map the distribution of lymph node metastases (LNM) in the groin area to facilitate an improved and detailed CTV definition using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). METHODS: Inguinal LNM in patients with biopsy-proven pelvic malignancies were identified using 18F-FDG PET/CT scan. The longitudinally nearest axial plane was determined based on six typical bony landmarks, and the axial direction relative to the femoral artery of LNM was recorded. The distances from the LNM to the nearest edge of the femoral artery were measured on the axial plane. An optimal margin to cover 95% of LNM was estimated to develop contouring recommendations. RESULTS: In this study, 500 positive LNM were identified by 18F-FDG PET/CT among 185 patients with primary pelvic malignancies. Relative to the femoral artery, lymph nodes were distributed laterally (10:00-11:00, n = 35), anteriorly (12:00-1:00, n = 213), and medially (2:00-4: 00, n = 252). For CTV delineation, the recommended distances from the femoral artery on the SFH were lateral 19 mm, anterior 19 mm, and medial 25 mm; on the SGT were lateral 26 mm, anterior 20 mm, and medial 25 mm; on the SPS were lateral 28 mm, anterior 29 mm, and medial 26 mm; on the IPS were anterior 29 mm and medial 28 mm; on the IIT were anterior 27 mm and medial 27 mm; on the ILT were anterior 25 mm and medial 23 mm. Use interpolation to contour the area between six axial slices, including any radiographically suspicious LNM. CONCLUSIONS: Using 18F-FDG PET/CT, we investigated the distribution pattern of inguinal LNM and propose a more comprehensive guideline for inguinal CTV delineation.