Fluorodeoxyglucose Uptake Research Articles

Bone and joint disease – Not always a rheumatological diagnosis

Abstract A 17-year-old female presented with a 7-day history of joint pains involving the bilateral knee, ankle and small joints of the hands and feet symmetrically, associated with bilateral knee joint swelling and early morning stiffness and bilateral red eyes. General examination was normal except for pallor. Musculoskeletal system examination revealed bilateral swollen and tender knee joints with restriction of movement along with tenderness in the bilateral shoulder, elbow, ankle joints and spine from T3 to T7 thoracic vertebral levels. Examination of other systems was normal. Investigations showed anaemia, elevated urea and creatinine. Skeletal survey showed multiple lytic lesions. Positron emission tomography revealed multiple punched-out lytic lesions in skull bones, scapulae, sternum, clavicles, ribs on both sides, vertebrae at multiple levels and in pelvic girdle bones. Few lesions showed mild 18fluorodeoxyglucose (18FDG) uptake, metaphyseal moth-eaten lysis in long bones with mild FDG uptake. Bone marrow biopsy and immunohistochemistry confirmed the diagnosis of acute B-cell lymphoblastic leukaemia. The terminology is according to 2016 revision of WHO classification of myeloid neoplasms and acute leukemia.

The Predictive Value of Changes in Basal Myocardial F-18 Fluorodeoxyglucose Uptake for Cardiotoxicity in Locally Advanced Esophageal Cancer Patients Receiving Definitive Radiotherapy

To investigate the predictive value of changes in myocardial 18F-FDG uptake for major adverse cardiac events (MACEs) in locally advanced esophageal cancer patients receiving definitive radiotherapy. Between August 2012 and January 2018, 400 patients with stage II-III esophageal cancer receiving definitive radiotherapy at two institutions were divided into the training (n = 240) and external validation cohorts (n = 160). All patients underwent FDG-PET imaging within 1 week before treatment and 3 months after treatment. Myocardium delineation was performed by Carimas software (version 2.10) based on the AHA 17-segment model. When contouring the left ventricle, the myocardium was automatically divided into basal (segments 1-6), middle (segments 7-12), and apical (segments 13-16) regions, and the mean dose and FDG uptake parameters of each region were obtained by Carimas. Our primary endpoint was MACEs. Patient clinicopathologic factors, dosimetric parameters for the whole heart and cardiac substructures, and myocardial changes within the three regions on 18F-FDG PET were utilized to seek the best predictive models for cardiotoxicity. To avoid multicollinearity between dose-volume histogram (DVH) parameters, we selected the variables with the lowest Akaike Information Criterion (AIC) value from the DVH parameters of the same cardiac structure for the actual modeling procedure. Competing risk analysis and Cox regressions analysis were performed. The predictive performance of the models was evaluated using the area under the receiver operating characteristic curve (AUC) and Brier score. At a median follow-up interval of 78 months, 28 patients (11.7%) developed MACEs. The basal region of the myocardium received the highest radiation dose, followed by the middle and the apex region. The basal myocardial SUVmax and SUVmean significantly increased after radiotherapy while the apical and middle myocardial SUVmax and SUVmean not significantly increased. In univariate analysis, age, pre-existing cardiac disease, changes in pre- and post-treatment basal myocardial SUVmax and SUVmean (∆SUVmax and ∆SUVmean), and dosimetric parameters for MHD, mean LCX, mean LAD, and mean LV dose were associated with an increased hazard of MACEs. Multivariate analysis showed that basal ∆SUVmean retained significance after adjusting for age, pre-existing cardiac disease, and dosimetric parameters for whole heart and cardiac substructures. The AUCs and Brier scores demonstrated favorable predictive accuracies of the model's integrating variables with significant difference in multivariate analysis when predicting MACEs in the training and validation cohorts. ∆SUVmean was an independent indicator of MACE in locally advanced esophageal cancer patients receiving definitive radiotherapy. Changes in basal myocardial FDG uptake is a promising biomaker for predicting radiation-induced cardiotoxicity.

Foreign Body Reaction Mimicking Lymph Node Metastasis is Not Rare After Lung Cancer Resection.

Mediastinal lymphadenopathies with high 18-fluorodeoxyglucose uptake in patients previously operated on for lung cancer are alarming for recurrence and necessitate invasive diagnostic procedures. Peroperative placement of oxidized cellulose to control minor bleeding may lead to a metastasis-like image through a foreign body reaction within the dissected mediastinal lymph node field at postoperative examinations. In this study, we investigated clinicopathological features and the frequency of foreign body reaction mimicking mediastinal lymph node metastasis. Patients who underwent surgery for lung cancer between January 2016 and August 2021 and who were subsequently evaluated for mediastinal recurrence with endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) were included. Patients were grouped according to the results of EBUS-TBNA as metastasis, foreign body, and reactive. Clinicopathological features of these patients were compared and characteristics of patients in the foreign body group were scrutinized. EBUS-TBNA was performed on a total of 34 patients during their postoperative follow-up due to suspicion of mediastinal recurrence. EBUS-TBNA pathological workup revealed metastasis in 18 (52.9%), foreign body reaction in 10 (29.4%) and reactive lymph nodes in 6 (17.6%) patients. Mean maximum standardized uptake value (SUVMax) for metastasis group and foreign body group were 9.39 ± 4.69 and 5.48 ± 2.54, respectively (p = 0.022). Time interval between the operation and EBUS-TBNA for the metastasis group was 23.72 ± 10.48 months, while it was 14.90 ± 12.51 months in the foreign body group (p = 0.015). Foreign body reaction mimicking mediastinal lymph node metastasis is not uncommon. Iatrogenic cause of mediastinal lymphadenopathy is related to earlier presentation and lower SUVMax compared with metastatic lymphadenopathy.

A case of cutaneous variant of intravascular large B-cell lymphoma in which dermoscopy revealed telangiectasias associated with erythematous induration.

Intravascular large B-cell lymphoma (IVLBCL) is a rare type of extranodal, diffuse, large B-cell lymphoma characterized by the selective growth of lymphoma cells within the lumen of small blood vessels, with no lymphadenopathy or masses. Herein, we report a cutaneous variant of IVLBCL that is rare in Asia. A healthy 73-year-old Japanese woman presented to our hospital with painful erythematous indurations and telangiectasia of the lower extremities, which was confirmed on dermoscopy. Physical examination revealed no systemic involvement, and laboratory parameters were within normal ranges. No abnormal fluorodeoxyglucose (FDG) uptake was detected on 18FDG positron emission tomography/computed tomography. Histopathological examination revealed proliferation and dilatation of blood vessels in the subcutis layer, occluded by CD20-positive atypical lymphoid cells. Thus, the patient was diagnosed with a cutaneous variant of IVLBCL without systemic symptoms. In conclusion, it is important to confirm telangiectasia using dermoscopy and perform skin biopsies in patients presenting with sudden-onset erythematous induration.

3D-OSEM versus FORE + OSEM: Optimal Reconstruction Algorithm for FDG PET with a Short Acquisition Time.

Objective In this study, we investigated the optimal reconstruction algorithm in fluorodeoxyglucose (FDG) positron emission tomography (PET) with a short acquisition time. Materials and Methods In the phantom study, six spheres filled with FDG solution (sphere size: 6.23-37 mm; radioactivity ratio of spheres to background = 8:1) and placed in a National Electrical Manufacturers Association phantom were evaluated. Image acquisition time was 15 to 180 seconds, and the obtained image data were reconstructed using each of the Fourier rebinning (FORE) + ordered subsets expectation-maximization (OSEM) and 3D-OSEM algorithms. In the clinical study, mid-abdominal images of 19 patients were evaluated using regions of interest placed on areas of low, intermediate, and high radioactivity. All obtained images were investigated visually, and quantitatively using maximum standardized uptake value (SUV) and coefficient of variation (CV). Results In the phantom study, FORE + OSEM images with a short acquisition time had large CVs (poor image quality) but comparatively constant maximum SUVs. 3D-OSEM images showed comparatively constant CVs (good image quality) but significantly low maximum SUVs. The results of visual evaluation were well correlated with those of quantitative evaluation. Small spheres were obscured on 3D-OSEM images with short acquisition time, but image quality was not greatly deteriorated. The clinical and phantom studies yielded similar results. Conclusion FDG PET images with a short acquisition time reconstructed by FORE + OSEM showed poorer image quality than by 3D-OSEM. However, images obtained with a short acquisition time and reconstructed with FORE + OSEM showed clearer FDG uptake and more useful than 3D-OSEM in the light of the detection of lesions.

A Rare Case of Pseudo-Malignant Paranasal Extranodal Rosai-Dorfman Disease.

Rosai-Dorfman disease is a very rare disease characterized by histiocytic accumulation in the head and neck region and lymph node enlargement. We report a rare pseudo-malignant paranasal extranodal Rosai-Dorfman disease. A 69-year-old-man presented nasal bleeding and nasal obstruction. Paranasal mass was detected in the left nasal cavity and computed tomography (CT) findings are the sphenoid sinus, maxillary sinus, and ethmoid sinus were involved with inconstant bone thickening, however, no bone destruction was detected. Magnetic resonance imaging scans show iso-intensity signal in T1-weighed image and T2-weighed image. Positron emission tomography/CT fluorodeoxyglucose (FDG) uptake in posterior ethmoid sinus and sphenoid sinus, bilateral cervical lymph node, clavicle, and sternum. Based on the above results, we considered malignant lymphoma and performed a biopsy. After pathological examination, a diagnosis of Rosai-Dorfman disease was established.

Subacute thyroiditis: clinical significance of diffuse 18-fluorodeoxyglucose uptake. Case report

Background. Subacute thyroiditis is a rare inflammatory thyroid disease presumably associated with viral infection, including COVID-19. It accounts for about 5% of all thyroid diseases.
 Materials and methods. A clinical case of de Quervain's subacute thyroiditis in a patient with diffuse hypermetabolic 18-fluorodeoxyglucose uptake by the thyroid gland is presented.
 Results. A 61-year-old patient with no history of thyroid disorders 3 weeks after COVID-19 experienced fever in the evenings (37.839.8C). He had moderate pain in the thyroid gland with radiation to the jaw, severe weakness, hand tremors, shivers, 12 kg weight loss, and sweating. These symptoms lasted for 3 weeks. Physical examination showed an enlarged thyroid gland, dense and extremely tender, especially its left lobe. Ultrasound showed an enlarged thyroid gland with a heterogeneous structure and large hypoechoic areas in both lobes up to 47 mm with fuzzy contour. Color Doppler imaging revealed reduced blood flow. Combined positron-emission and X-ray computed tomography with 18-fluorodeoxyglucose showed an increased diffuse uptake of the radiopharmaceutical in the thyroid gland and enlargement of its lobes, SUVmax 10.55. Blood thyroid-stimulating hormone is low, free triiodothyronine and thyroxine are high, and ferritin concentration is markedly increased, consistent with thyrotoxicosis. A fine-needle aspiration biopsy was performed. Cytology confirmed de Quervain's subacute thyroiditis. Glucocorticoids and nonsteroidal anti-inflammatory drugs were administered. Four weeks after the treatment, the clinical manifestations resolved. The patient was assessed in 6 months. Ultrasound showed a thyroid gland of regular size with smooth contours; color Doppler mapping revealed normal blood flow. Thyroid-stimulating hormone, triiodothyronine, and thyroxine were within reference ranges.
 Conclusion. The SARS-CoV-2 virus can be regarded as the cause of subacute thyroiditis. Combined positron-emission and X-ray computed tomography with 18-fluorodeoxyglucose showed diffuse intensive radiopharmaceutical uptake in the thyroid gland. Cytology is the basis for differential diagnostics. Glucocorticoids and nonsteroidal anti-inflammatory drugs are the first-choice agents.

Prednisone vs methotrexate in treatment naïve cardiac sarcoidosis

BackgroundSide effects limit the long-term use of glucocorticoids in cardiac sarcoidosis (CS), and methotrexate has gained attention as steroid sparing agent although the supporting evidence is poor. This study compared prednisone monotherapy, methotrexate monotherapy or a combination of both, in the reduction of myocardial Fluorine-18 fluorodeoxyglucose (FDG) uptake and clinical stabilization of CS patients. Methods and resultsIn this retrospective cohort study, 61 newly diagnosed and treatment naïve CS patients commenced treatment with prednisone (N = 21), methotrexate (N = 30) or prednisone and methotrexate (N = 10) between January 2010 and December 2017. Primary outcome was metabolic response on FDG PET/CT and secondary outcomes were treatment patterns, major adverse cardiovascular events, left ventricular ejection fraction, biomarkers and side effects. At a median treatment duration of 6.2 [5.7-7.2] months, 71.4% of patients were FDG PET/CT responders, and the overall myocardial maximum standardized uptake value decreased from 6.9 [5.0-10.1] to 3.4 [2.1-4.7] (P < 0.001), with no significant differences between treatment groups. During 24 months of follow-up, 7 patients (33.3%; prednisone), 6 patients (20.0%; methotrexate) and 1 patient (10.0%; combination group) experienced at least one major adverse cardiovascular event (P = 0.292). Left ventricular ejection fraction was preserved in all treatment groups. ConclusionsSignificant suppression of cardiac FDG uptake occurred in CS patients after 6 months of prednisone, methotrexate or combination therapy. There were no significant differences in clinical outcomes during follow-up. These results warrant further investigation of methotrexate treatment in CS patients.

Increased 18 F-fluorodeoxyglucose uptake mimicking malignant lung tumour in a cat with lipid pneumonia.

Increased 18 F-fluorodeoxyglucose uptake mimicking malignant lung tumour in a cat with lipid pneumonia.

The value of [18F]FDG PET/CT in avoiding overtreatment of 131l avidity pulmonary metastasis of differentiated thyroid cancer.

We usually use 131I-whole body scan (131I-WBS) and serum thyroglobulin (Tg) values to determine whether differentiated thyroid cancer (DTC) patients need to receive 131I treatment, but not all ¹³¹I-avid (functioning) patients have a good response to ¹³¹I therapy. Our study aims to assess the data of [¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography ([¹⁸F] FDG PET/CT) to research the status of 131I-avid pulmonary metastases (PMs) and the prognosis of the patients. The 131I-avid PMs of DTC patients who underwent [18F]FDG PET/CT scans were included. The maximum standardized uptake value (SUVmax), metabolic tumour volume (MTV), and total lesion glycolysis (TLG) were used to estimate [¹⁸F]FDG uptake. The mean follow-up period was 34.14 ± 18.64 months. Progression-free survival (PFS) was estimated by the Kaplan-Meier method. The study was based on per-patient and per-lesion analyses. Among the 42 included patients, 34 (34/42, 81%) showed [¹⁸F]FDG uptake, which was defined as abnormal foci (SUVmax > 1.0) in the lungs. SUVmax, MTV, TLG, and tumour size were the factors that influenced the outcome of 131I treatment based on Tg levels (p = 0.000, 0.016, 0.000, 0.000) in per-lesion analysis. The only independent factor was the size of the lesion. There was a significant difference in response to ¹³¹I therapy between PMs with F-I+ and F+/I+ according to both Tg levels and Response Evaluation Criteria in Solid Tumours (RECIST) (version 1.1) (p = 0.044, 0.001), in the per-lesion analysis. When the changes in size or metabolism of some lesions are inconsistent the prognosis of these patients is poor (p = 0.003). We concluded that higher [18F]FDG uptake and larger tumour size predict poor therapeutic effects and a high risk of disease progression in ¹³¹I-avid PMs of DTC. For evaluating the efficiency of ¹³¹I treatment, per-lesion analyses and assessing the data of [¹⁸F] FDG PET/CT would be more reliable than per-patient evaluation only. And early focal treatment modalities may improve their life span.

Laparoscopic resection of a metastatic myxoid liposarcoma in the mesentery of the small intestine: a case report

BackgroundMyxoid liposarcoma (MLS), with its risk factors, tends to spread to the lungs and extraperitoneally, with intraperitoneal metastases occurring rarely. We present an unusual case of a myxoid liposarcoma that metastasized to the abdominal organs.Case presentationA 60-year-old female patient was referred to our hospital for the evaluation of a right upper limb tumor that had been growing for 7 years. The patient refused surgery, and during follow-up, tumor hemorrhage resulted in hemorrhagic shock. The patient’s right upper limb was immediately amputated. MLS was diagnosed histopathologically. Subsequently, the patient underwent adjuvant chemotherapy. Computed tomography (CT) revealed a right buttock mass, a pelvic mass, and left cardiophrenic angle lymph nodes 3 years after the initial surgery. Contrast-enhanced abdominal CT revealed a relatively low-density, lobulated pelvic tumor. Contrast-enhanced pelvic magnetic resonance imaging (MRI) revealed a low-intensity, lobulated mass on T1-weighted images and a high-intensity mass on T2-weighted images. The pelvic mass showed no significant fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET)-CT. On clinical examination, gynecological malignancies were ruled out as the origin of the pelvic lesions. After resection of the right buttock mass, pelvic mass, and left cardiophrenic angle lymph nodes, the patient underwent laparoscopic surgery for a preoperative diagnosis of small intestinal mesenteric metastasis of MLS. A tumor was found in the mesentery of the small intestine and removed with a margin of 5 cm on both the proximal and distal sides. The specimen measured 10 × 8 × 5 cm and contained a multifocal mass. The tumor was found in the mesentery of the small intestine, with no mucosal or submucosal invasion. The patient was diagnosed with MLS with small mesenteric intestinal metastases. On postoperative day 8, the patient was discharged after an uneventful postoperative course. Twelve months after the surgery, there was no evidence of local or distant recurrence.ConclusionsSmall intestinal mesenteric metastases of MLSs are rare. Moreover, there are few reports on laparoscopic resection. In this case, the laparoscopic approach was useful in detecting the tumor location and determining the range of resection.

Development of lung cancer risk prediction models based on F-18 FDG PET images.

We aimed to evaluate whether the degree of F-18 fluorodeoxyglucose (FDG) uptake in the lungs is associated with an increased risk of lung cancer and to develop lung cancer risk prediction models using metabolic parameters on F-18 FDG positron emission tomography (PET). We retrospectively included 795 healthy individuals who underwent F-18 FDG PET/CT scans for a health check-up. Individuals who developed lung cancer within 5years of the PET/CT scan were classified into the lung cancer group (n = 136); those who did not were classified into the control group (n = 659). The healthy individuals were then randomly assigned to either the training (n = 585) or validation sets (n = 210). Clinical factors including age, sex, body mass index (BMI), and smoking history were collected. The standardized uptake value ratio (SUVR) and metabolic heterogeneity (MH) index were obtained for the bilateral lungs. Logistic regression models including clinical factors, SUVR, and MH index were generated to quantify the probability of lung cancer development using a training set. The prediction models were validated using a validation set. The lung SUVR and lung MH index in the lung cancer group were significantly higher than in the control group (p < 0.001 and p < 0.001, respectively). In the combined prediction model 1, age, sex, BMI, smoking history, and lung SUVR were significantly associated with lung cancer development (age: OR 1.07, p < 0.001; male: OR 2.08, p = 0.015; BMI: OR 0.93, p = 0.057; current or past smoker: OR 5.60, p < 0.001; lung SUVR: OR 1.13, p < 0.001). In the combined prediction model 2, age, sex, BMI, smoking history, and lung MH index showed a significant association with lung cancer development (age: OR 1.06, p < 0.001; male: OR 1.87, p = 0.045; BMI: OR 0.93, p = 0.010; current or past smoker: OR 4.78, p < 0.001; lung MH index: OR 1.33, p < 0.001). In the validation data, combined prediction models 1 and 2 exhibited very good discrimination [area under the receiver operator curve (AUC): 0.867 and 0.901, respectively]. The metabolic parameters on F-18 FDG PET are related to an increased risk of lung cancer. Metabolic parameters can be used as biomarkers to provide information independent of the clinical parameters, related to lung cancer risk.

Imaging increased metabolism in the spinal cord in mice after middle cerebral artery occlusion

Emerging evidence indicates crosstalk between the brain and hematopoietic system following cerebral ischemia. Here, we investigated metabolism and oxygenation in the spleen and spinal cord in a transient middle cerebral artery occlusion (tMCAO) model. Sham-operated and tMCAO mice underwent [18F]fluorodeoxyglucose (FDG)-positron emission tomography (PET) to assess glucose metabolism. Naïve, sham-operated and tMCAO mice underwent multispectral optoacoustic tomography (MSOT) assisted by quantitative model-based reconstruction and unmixing algorithms for accurate mapping of oxygenation patterns in peripheral tissues at 24 h after reperfusion. We found increased [18F]FDG uptake and reduced MSOT oxygen saturation, indicating hypoxia in the thoracic spinal cord of tMCAO mice compared with sham-operated mice but not in the spleen. Reduced spleen size was observed in tMCAO mice compared with sham-operated mice ex vivo. tMCAO led to an increase in the numbers of mature T cells in femoral bone marrow tissues, concomitant with a stark reduction in these cell subsets in the spleen and peripheral blood. The combination of quantitative PET and MSOT thus enabled observation of hypoxia and increased metabolic activity in the spinal cord of tMCAO mice at 24 h after occlusion compared to sham-operated mice.

Multimodality imaging of myocardial tuberculosis presenting as right ventricular cardiomyopathy: A case report.

An 18-year male with no significant past medical history presented with features of right-sided heart failure. Haematological investigations revealed raised erythrocyte sedimentation rate (23 mm/h). Transthoracic echocardiography (TTE) demonstrated biventricular systolic dysfunction with thickened free wall of right ventricle (RV). Whole-body fluorodeoxyglucose (FDG)-positron emission tomography (PET) computed tomography (FDG-PET-CT) showed intensely increased FDG uptake in the thickened RV wall and an FDG avid lesion in the left medial temporal lobe. Cardiac magnetic resonance imaging (CMR) characterized thickening and suggested an infiltrative disease (isointense on TI, hyperintense on myocardial oedema sensitive sequence with transmural enhancement on late gadolinium sequence). Magnetic resonance imaging (MRI) brain showed a thick rim enhancing ring lesion in the body of hippocampus. Endomyocardial biopsy revealed moderately dense lymphomononuclear inflammation with the formation of granulomas. Since tuberculosis is endemic in our country and considering all laboratory, imaging and biopsy findings a working diagnosis of tuberculosis was considered, and standard anti-tubercular treatment was started. There was an improvement in clinical status and follow-up imaging (TTE, CMR, brain MRI and FDG-PET-CT) showed improvement in biventricular function with regression in myocardial thickening and resolution of brain lesion, confirming the diagnosis of tuberculosis.

Cardiac cavernous hemangioma with high fluorodeoxyglucose uptake on preoperative positron emission tomography/computed tomography: a case report

BackgroundReports on cardiac hemangioma detection by F-18-deoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) are extremely rare.Case presentationHere we describe a case of a 61-year-old man with hemangioma. CT revealed a tumor with a size of 60 mm. Magnetic resonance imaging showed high signal intensity on T2-weighted images. Hemangioma was initially suspected. However, PET/CT showed high FDG absorption, which led us to suspect a malignant tumor. The tumor was resected, and a cavernous hemangioma diagnosis was made by postoperative histopathological examination.ConclusionsThis case may serve as a reference for clinicians to become more aware of the potential application of FDG PET/CT for cardiac hemangioma detection.

A rare case of giant hepatic angiomyolipoma with subcapsular rupture.

Hepatic angiomyolipoma (HAML) is a rare mesenchymal neoplasm that predominantly affects middle-aged women. In this study, we present a case of a 49-year-old woman with a giant HAML accompanied by spontaneous subcapsular rupture. The patient initially experienced nausea and abdominal distention, followed by an enlargement of the upper abdominal circumference. Laboratory examination revealed decreased serum hemoglobin, while tumor biomarkers were within normal ranges. Imaging studies, such as abdominal ultrasound and contrast-enhanced computed tomography (CT), demonstrated a large upper abdominal mass with heterogeneous density and hypervascularity. The tumor appeared to have invaded the left liver, raising concerns about possible malignancy. Subsequent positron-emission tomography/CT confirmed increased fluorodeoxyglucose uptake in the mass. Laparoscopic exploration revealed a protruding, well-encapsulated tumor from the left liver, exhibiting subcapsular hemorrhage. Surgical resection of the tumor and the left liver was performed, leading to a successful outcome.

Follicular cholangitis mimicking a common bile duct cancer: a case report

BackgroundFollicular cholangitis (FC) is a benign bile duct disease that was first reported 2003. Pathologically, it is characterized by lymphoplasmacytic infiltration with multiple lymphoid follicle formations under the mucosal layer of the biliary tract. However, as this disease is extremely rare, little is known about its etiology and pathogenesis.Case presentationA 77-year-old woman was diagnosed with middle bile duct stenosis and potential increases in alkaline phosphatase (ALP) and γ-glutamyl transpeptidase levels (γ-GTP). Carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA19-9) and IgG4 levels were all within the normal limits. Contrast-enhanced computed tomography (CE-CT) and magnetic resonance imaging (MRI) revealed bile duct dilation from intrahepatic to upper common bile duct and an irregular mass lesion in distal bile duct. Additionally, multiple overlapping leaf-like folds were detected. 18F-fluorodeoxyglucose positron emission tomography–computed tomography (18F-FDG-PET/CT) did not demonstrate fluorodeoxyglucose uptake. Subtotal stomach-preserving pancreaticoduodenectomy with regional lymph node dissection was performed because common bile duct cancer could not be ruled out. The resected specimen showed diffuse homogeneous middle bile duct wall thickening. Microscopically, the lesion exhibited thick fibrosis with several invaded lymphoplasmacytic cells, and lymphoid follicle formations were detected under the mucosal layer. Immunohistochemical staining (IHC) revealed positive for CD3, CD4, CD20 and CD79a, and these findings led to a final diagnosis of FC. The patient has not experienced recurrence to date (42 months postoperatively).ConclusionsCurrently, accurate preoperative diagnosis of FC is difficult. More cases must be accumulated to generate additional knowledge on its precise diagnosis and proper treatment.

Time-Related Vascular Inflammatory Response to COVID-19 Assessed by 18F-FDG PET/CT in Follow-Up Tumor Patients.

This study aimed to assess COVID-19's effects on vascular inflammatory response, by evaluating 18-Fluorodeoxyglucose (18F-FDG) uptake via positron emission tomography/computed tomography (PET/CT) in the artery of diffuse large B cell lymphoma (DLBCL) patients before and after infection with COVID-19. Thirty-five DLBCL patients administered the chemotherapy regimen R-CHOP and examined by oncological 18F-FDG PET/CT imaging twice from August 2022 to February 2023 for pre-treatment evaluation or assessment of treatment efficacy were enrolled. Seventeen patients were confirmed with COVID-19 within the study period. Arterial wall FDG uptake was semi-quantitatively analyzed as TBR (target-to-blood pool ratio) in 14 different vascular regions using oncological 18F-FDG PET/CT. Based on COVID-19 course and the two PET/CT scans, we further analyzed time-related FDG uptake for vascular walls in DLBCL patients with COVID-19. Arterial TBRs were higher in the last PET/CT examination than previous ones in all patients with or without COVID-19. Besides the ascending aorta, ΔTBR (last PET/CT scanning's TBR minus previous PET/CT scanning's TBR) were not significantly different between the COVID-19 and Control groups. However, cases scanned ≤30 days from infection had remarkably higher ΔTBRs in comparison with those assessed >30 days post-infection in the COVID-19 group (p<0.05). A moderate inverse correlation was observed between ∆Global TBR (last PET/CT scanning's average TBR value minus previous PET/CT scanning's average TBR value) and time distance from COVID-19 onset to 18F-FDG PET/CT scan (Spearman's rho=-0.591, P=0.012). Interestingly, there were no differences of changes of TBR between different purpose of PET/CT examination group. This work firstly suggested vascular inflammation is elevated in the early post-COVID-19 phase in DLBCL cases compared with prolonged post-COVID-19 phase or controls. Increasing attention should be paid to these patients and the protection of their vascular function and complications in early COVID-19.

Somatostatin Receptor Targeted PET-CT and Its Role in the Management and Theranostics of Gastroenteropancreatic Neuroendocrine Neoplasms

Somatostatin receptor (SSTR) agonist-based Positron Emission Tomography-Computed Tomography (PET-CT) imaging is nowadays the mainstay for the assessment and diagnostic imaging of neuroendocrine neoplasms (NEN), especially in well-differentiated neuroendocrine tumors (NET) (World Health Organization (WHO) grade I and II). Major clinical indications for SSTR imaging are primary staging and metastatic workup, especially (a) before surgery, (b) detection of unknown primary in metastatic NET, (c) patient selection for theranostics and appropriate therapy, especially peptide receptor radionuclide therapy (PRRT), while less major indications include treatment response evaluation on and disease prognostication. Dual tracer PET-CT imaging using SSTR targeted PET tracers, viz. [68Ga]Ga-DOTA-Tyr3-Octreotate (DOTA-TATE) and [68Ga]Ga-DOTA-NaI3-Octreotide (DOTA-NOC), and fluorodeoxyglucose (FDG), have recently gained widespread acceptance for better assessment of whole-body tumor biology compared to single-site histopathology, in terms of being non-invasive and the ability to assess inter- and intra-tumoral heterogeneity on a global scale. FDG uptake has been identified as independent adverse risk factor in various studies. Recently, somatostatin receptor antagonists have been shown to be more sensitive and specific in detecting the disease. The aim of this review article is to summarize the clinical importance of SSTR-based imaging in the clinical management of neuroendocrine and related tumors.

866-P: Quantitative Analysis of Metformin-Induced Glucose Excretion in the Intestine

The enhancement of the uptake of 18F-labeled fluorodeoxyglucose (FDG) during [18F]FDG PET is a recently found metformin action in the gut. Taking advantage of PET-MRI, which provides better tissue registration and soft-tissue contrast than conventional PET-CT, we revealed that metformin enhanced FDG accumulation in the intestinal lumen. We now quantitatively analyzed the phenomenon with a newly developed protocol of PET-MRI. We also analyzed the intestinal glucose dynamics using 13C-labeled glucose and mass spectrometry in mice. We adopted imaging sequences of MR enterography to create 3D images of the intestinal tract, then superimposed the [18F]FDG PET images to obtain the 3D distribution of radioactivity. We conducted this test on type 2 diabetes subjects treated (N=5) or not (control, N=5) with metformin. Radioactivity was detected in the wall and lumen at similar extents in the control. However, in the metformin group, the radioactivity in the lumen, but not the wall, was three to four-fold greater than that in the control. We mathematically analyzed the data using a compartment model and calculated the glucose excretion rate (GER). GER of the control and metformin groups were 6.8 ± 1.2 mg/min and 26.1 ± 2.9 mg/min, respectively, the latter being comparable to glucose excretion into the urine induced by SGLT2 inhibitors. For mouse experiments, we intravenously injected 13C-glucose into C57/B6 mice and analyzed the feces 1 hour after injection with a gas chromatography-quadrupole mass spectrometry. We could not detect 13C-glucose in the feces, possibly because gut microbiota metabolizes glucose in the intestine. However, the content of 13C in short-chain fatty acids (SCFAs) was increased by the injection of 13C-glucose, and metformin augmented the incorporation of 13C into SCFAs. These results suggest that glucose in the circulation transfers to the intestinal lumen at a considerable rate and is metabolized by microbiota, at least partly, into SCFAs and that metformin augments the processes. Disclosure Y.Hosokawa: None. K.Sakaguchi: Research Support; Sumitomo Dainippon Pharma Co., Ltd. J.Ito: None. K.Sugawara: None. Y.Morita: None. W.Ogawa: Advisory Panel; Abbott Japan Co., Ltd., Research Support; Boehringer Ingelheim Japan, Inc., Eli Lilly Japan K.K., Novo Nordisk, Teijin Pharma Limited, Kowa Company, Ltd., Sumitomo Dainippon Pharma Co., Ltd., Abbott Japan Co., Ltd., Speaker's Bureau; Sumitomo Dainippon Pharma Co., Ltd. Funding Japan Society for the Promotion of Science (21K08578, 22K18393)