Hutch diverticulum (HD) is a rare congenital condition characterized by the herniation of the bladder’s mucosa and submucosa through the detrusor muscle fibers, encountered more commonly in children. An association between HD and situs inversus totalis (SIT) in an elderly patient has not been reported previously in the literature. We present the case of a 70-year-old male referred for routine bone scintigraphy as part of staging for lung carcinoma; thoraco-abdomino-pelvic computed tomography confirmed the staging and revealed a total transposition of the thoracic and abdominal organs, confirming SIT. This case highlights the exceptional association of HD and SIT, which was discovered incidentally in an elderly patient during metastatic staging for lung cancer. It underscores the importance of careful interpretation of scintigraphic findings, particularly when unusual radiotracer uptake is observed.
Approximately 85-90% of all rhabdomyosarcoma (RMS) cases occur in children and adolescents. In adults, RMS accounts for only 2-5% of all soft tissue sarcomas. The annual incidence in adults is 0.3-0.5 per 1,000,000 and is classified as a "very rare tumor." More than 95% of RMSs are extragastric. Primary gastric RMS is reported extremely rarely in adults, and the estimated incidence is <0.01/1,000,000/year. This rate is <0.01% of all gastric malignancies and <1% of all adult RMSs. We report the 18F-fluorodeoxyglucose positron emission tomography/computed tomography findings in an adult with primary gastric alveolar RMS, highlighting the metabolic characteristics of this extraordinarily rare malignancy.
Fat necrosis, a benign postoperative process related to tissue injury and repair, may demonstrate variable findings on functional imaging. We report a case of postoperative fat necrosis following pancreaticoduodenectomy showing intense 68Ga-FAPI uptake in the absence of significant 18F-fluorodeoxyglucose (18F-FDG) avidity. Surveillance 18F-FDG positron emission tomography/computed tomography (18F-FDG PET/CT) demonstrated only mild activity within the surgical bed maximum standard uptake value (SUVmax 2.4), while subsequent 68Ga-FAPI PET/CT revealed marked uptake corresponding to fat necrosis SUVmax 9.9, consistent with pronounced fibroblast activation during postoperative healing. Additionally, a benign left adrenal adenoma showed low 18F-FDG uptake and only minimal 68Ga-FAPI avidity (SUVmax 2.3), reflecting minimal stromal activation. This case highlights the tracer discordance between 18F-FDG and 68Ga-FAPI in fat necrosis and underscores the importance of correlating 68Ga-FAPI findings with surgical history and anatomic imaging to ensure accurate interpretation.
Dementia in individuals with Down syndrome (DS) is the leading cause of early-onset cognitive decline occurring before the age of 50. However, establishing an accurate diagnosis remains particularly challenging due to pre-existing intellectual disability, variability in baseline cognitive function, and the limited reliability of standard neuropsychological assessments. 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) plays a critical role in identifying underlying neurodegenerative processes and supporting the diagnosis. We present a case of DS with multiple known and unknown pathologies identified on brain 18F-FDG PET and a confirmed diagnosis of early-onset mild Alzheimer's disease.
Cavernous sinus metastasis from follicular thyroid carcinoma (FTC) is exceedingly rare and typically indicates advanced, radioiodine-refractory disease. We report a 37-year-old man with minimally invasive FTC who was treated with total thyroidectomy, neck dissection, and cumulative radioiodine therapy totaling 720 mCi for persistent iodine-avid disease. Four years later, he developed progressive left-sided palsies of cranial nerves III, IV, and VI. Imaging revealed a cavernous sinus mass with orbital apex extension and perineural spread. Serum thyroglobulin was markedly elevated (>500 ng/mL), whereas diagnostic radioiodine scintigraphy demonstrated no uptake, a finding consistent with dedifferentiated disease. Biopsy confirmed metastatic FTC. The patient received external beam radiotherapy and systemic therapy with lenvatinib; however, the disease progressed, and he died 16 months after the diagnosis of cavernous sinus metastasis. This case highlights the aggressive potential of FTC, the limitations of radioiodine imaging in dedifferentiated disease, and the poor prognosis associated with skull-base metastases despite multimodal therapy.
Metastatic calcification is characterized by abnormal deposition of calcium in extraosseous tissues resulting from disruption of calcium-phosphorus homeostasis. It occurs without tissue damage and is usually seen in normal organs. It is most commonly observed in patients with chronic renal failure, paraneoplastic hypercalcemia, and vitamin D intoxication. Metabolic superscan is characterized by diffusely increased skeletal activity with suppressed renal visualization, often without soft-tissue involvement. This pattern reflects altered radiotracer biodistribution secondary to severe metabolic bone turnover. We report a case of multiple myeloma in which diffuse 99mTc-MDP uptake was observed in the stomach on a metabolic superscan.
Objectives: The multi-time-point imaging method for renal dosimetry in lutetium-177 (177Lu)-DOTATATE therapy imposes a significant burden. This study aimed to validate simplified two-time-point (2TP) and three-time-point (3TP) protocols using the International Commission on Radiological Protection-compliant IDAC-Dose 2.1 software. Methods: This retrospective study analyzed 28 kidneys obtained from 17 patients with neuroendocrine neoplasms. Renal absorbed doses from a reference four-time-point (4TP) schedule (4, 24, 72, and 120 hours) were compared with ten simplified protocols using statistical analyses of error and agreement. Results: Protocols that included the 120-hour time point demonstrated significantly higher accuracy. The 2TP (4, 24) protocol showed a profound underestimation [mean percentage error (MPE):-14.3%] and a high error. In contrast, the 2TP (24, 120) protocol showed excellent agreement [MPE: 0.57%, mean absolute percent error (MAPE): 5.5%]. Among 3TP methods, the 3TP (24, 72, 120) protocol yielded the highest accuracy (MAPE: 1.97%). Conclusion: Accurate renal dosimetry in 177Lu-DOTATATE therapy can be achieved with simplified protocols. Incorporating a late-phase time point (around 120 hours) is essential for reliable estimation. The 2TP (24, 120) and 3TP (24, 72, 120) combinations are suggested as feasible alternatives to the standard 4TP method.
Objectives:Endometrial cancer is the second most common gynaecologic cancer in women worldwide. Due to the biology of endometrial cancer, most patients are overweight. Standard uptake value (SUV) measurements are known to vary depending on the patient's body weight. We aimed to evaluate whether lean body mass-adjusted 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) parameters [lean body mass-corrected standardized uptake value (SUL)-based metrics] are superior to conventional SUV-based parameters for predicting adverse histopathologic features in overweight patients with endometrial cancer, and to explore their association with progression-free survival (PFS). Methods:In this retrospective single-center study, 73 overweight patients with endometrial cancer who underwent preoperative 18F-FDG PET/CT followed by primary surgery were included. SUV- and SUL-based metabolic parameters were compared with histopathologic risk factors. ROC analyses were performed to determine discriminatory performance and optimal cut-off values. PFS was assessed using Kaplan-Meier analysis. Results:SUVmean (SULmean) demonstrated significant associations with deep myometrial invasion, lymphovascular space invasion, lymph node involvement, and higher tumor grade. In ROC analysis, SULmean showed moderate discriminatory ability for lymph node involvement (area under the curve: 0.78). However, PFS did not differ significantly between groups stratified by the ROC-derived SULmean cut-off (log-rank p=0.46). Conclusion:Lean body mass-adjusted PET parameters, particularly SULmean, were more strongly associated with adverse histopathologic features than conventional SUV metrics in overweight patients with endometrial cancer. Although SUL-based parameters may contribute to preoperative risk assessment, their prognostic value for survival remains uncertain.
Primary squamous cell urachal carcinoma is an exceedingly rare epithelial neoplasm and an aggressive malignancy, originating from the urachal remnants. In contrast to mucinous adenocarcinoma, the most common histological type, squamous cell urachal carcinoma demonstrates high 2-deoxy-2-18F-fluorodeoxyglucose (18F-FDG) uptake, making 18F-FDG positron emission tomography/computed tomography (PET/CT) a valuable tool for evaluating regional lymph node involvement and detecting distant metastases. Optimal surgical management, the need for systemic therapy, and the overall prognosis are largely determined by accurate clinical staging, which is mainly based on the widely recognized Sheldon and Mayo classifications. We present a rare case of primary squamous cell urachal carcinoma on18F-FDG PET/CT in a young woman, with correlation to surgical and histopathological findings.
Mediastinal paragangliomas (PGLs) are extremely rare neuroendocrine tumors. Clinical presentation varies and tumor resection can be challenging due to bleeding and risk of catecholamine surges in functional tumors. We report on a case 68 with a DOTATATE avid mediastinal mass which was histopathologically confirmed as a PGL that was fed by the coronary artery in whole-body positron emission tomography/computed tomography imaging using gallium-68-DOTATATE.
We report the case of a 31-year-old woman with osseous Hodgkin's lymphoma who underwent post-therapeutic 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography. The scan revealed a hypermetabolic lesion in the pubic symphysis and iliac crests, initially suggestive of residual disease. Multimodal evaluation, including 99mTc-methoxy-isobutyl-isonitrile scintigraphy, laboratory tests revealed primary hyperparathyroidism, and biopsy confirmed a brown tumor. This case highlights the importance of integrating multimodal imaging and pathology to avoid misinterpretation of 18F-FDG-avid lesions.
Oncocytic carcinoma of the salivary glands is a very rare entity, that mainly presents in the parotid gland, either arises de-novo or is being associated with a benign oncocytoma in up to 50%. Our patient was a 60 years old male with histopathological finding of oncocytic (oxyphilic) carcinoma originating from the parotid gland with metastasis in cervical lymph nodes (postoperative stage IVA, pTNM = pT2 pN2b pMx G2 R0). On the initial preoperative 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) increased metabolic activity was seen in level IB and IIA cervical lymph nodes, suspicious for metastasis. Surgical biopsy of the parotid gland revealed oncocytic carcinoma, and then radical surgery was performed. Afterwards, patients started with immunotherapy, but because of disease progression (metastasis in the cervical, axillary, mediastinal lymph nodes and thyroid) detected on the control PET/CT scans, he was switched to chemotherapy. The patient died four years after being diagnosed with the primary cancer.
Gliomas are the most common primary malignant brain tumors and are characterized by heterogeneous growth and complex biology, which complicate accurate diagnosis and management. While magnetic resonance imaging (MRI) remains the clinical standard, its limitations in delineating tumor margins and distinguishing recurrence from treatment-induced changes highlight the need for complementary molecular imaging. 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) has been extensively studied, providing valuable prognostic information by reflecting tumor glycolytic activity. However, its diagnostic utility is hampered by high cortical background uptake and by poor sensitivity in detecting low-grade gliomas. Conversely, glioma-68 fibroblast activation protein inhibitor (FAPI) PET targets cancer-associated fibroblasts, offering superior tumor-to-background contrast and improved visualization of infiltrative margins. Comparative studies suggest that FAPI PET better discriminates between low- and high-grade gliomas, correlates with tumor stromal activity, and aids in therapy planning by differentiating true progression from post-treatment changes. Despite these advantages, the evidence base for FAPI remains limited, largely derived from small cohorts and pilot studies. Standardized imaging protocols and larger prospective trials are necessary to validate its role. Overall, 18F-FDG and FAPI PET provide complementary insights into glioma biology, and their integration with MRI and amino acid tracers may refine diagnostic accuracy, therapeutic planning, and prognostic assessment in clinical neuro-oncology.
Tumor-induced osteomalacia, resulting from tumoral overproduction of fibroblast growth factor 23, is a rare paraneoplastic syndrome clinically characterized by muscle weakness, bone pain, and pathological fractures. Fewer than 1,000 cases have been reported in the literature. Laboratory findings typically include hypophosphatemia, normal or decreased levels of 1.25-dihydroxy vitamin D, and normal or elevated levels of FGF23. Functional imaging methods, particularly somatostatin receptor imaging, play an important role in the localization of the tumor. In this case of tumor-induced osteomalacia, we presented the findings from gallium-68 (68Ga)-DOTATATE, 68Ga-fibroblast, and 18F-fluorodeoxyglucose positron emission tomography imaging modalities used for tumor localization.
Objective:To investigate whether gallium-68 fibroblast activation protein inhibitor positron emission tomography/computed tomography 68Ga-FAPI PET/CT is superior to 18F-fluorodeoxyglucose positron emission tomography (18F-FDG) PET/CT in the staging of patients with laryngeal cancer (LC). Methods:A total of 14 patients diagnosed with LC were retrospectively included in the study, of whom 13 were male and 1 female, with a mean age of 65 years. All participants were initially referred to our department for staging with 18F-FDG PET/CT. Subsequently, each patient underwent a 68Ga-FAPI PET/CT scan three days following the 18F-FDG PET/CT. Both sets of imaging studies were independently evaluated by two experienced nuclear medicine physicians, and the findings were systematicaly compared to assess potential differences in diagnostic performance. Results:The median maximum standard uptake values (SUVmax) of primary tumors was significantly higher in 68Ga-FAPI PET/CT 10.95; range: 3.5-19.2) compared to 18F-FDG PET/CT (4.85; range: 2.2-10.9). Lymph node involvement was observed on FDG scans in 3 patients, in ipsilateral levels 2 and/or 3, with a median SUVmax of 3.7 (range: 2.4-4.1). FAPI PET/CT also detected lymph node involvement at the same levels in 3 patients, with a notably higher SUVmax of 7.9 (range: 6.8-10.4). Conclusion:In this study, our results suggest that 68Ga-FAPI PET/CT demonstrates superior radiotracer uptake in both primary tumors and lymph nodes, which may enhance detection sensitivity for LC staging compared with 18F-FDG PET/CT. Nevertheless, further prospective studies with larger patient populations are warranted to validate these preliminary observations and determine the clinical value of this emerging imaging modality.
Spinal cord involvement is a rare manifestation of metastatic ovarian carcinoma. We report a case of high-grade serous ovarian cancer initially diagnosed in 2020. After cytoreductive surgery and multiple chemotherapy regimens, the patient developed brain metastases followed by small hypermetabolic foci along the spinal canal detected on18F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (18F-FDG PET/MRI). These lesions, primarily located in the cervical region, were confirmed by contrast-enhanced spinal MRI but were more clearly visualized on 18F-FDG PET/MRI. Intramedullary spinal cord metastases are extremely rare and often underdiagnosed. While MRI remains the standard for anatomical assessment, 18F-FDG PET/MRI demonstrated superior lesion detection and definition in this case. This highlights the potential of hybrid imaging for improved diagnostic sensitivity in patients with suspected central nervous system involvement.
Diffuse hepatic involvement in multiple myeloma is rare and may present a diagnostic challenge 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). We present the case of a 59-year-old man with a 3-year history of multiple myeloma who developed progressive hepatomegaly and perihepatic ascites. 18F-FDG PET/CT demonstrated marked diffuse liver enlargement without any focal or diffuse hepatic 18F-FDG uptake, while mild diffuse skeletal uptake suggested a globally 18F-FDG-low myeloma phenotype. Given the discordance between severe morphological findings and the absence of hepatic metabolic activity, a liver biopsy was performed, which revealed diffuse sinusoidal infiltration by CD138-positive, lambda-restricted plasma cells and excluded hepatic amyloidosis. Following systemic therapy, hepatomegaly and ascites regressed, while hepatic 18F-FDG uptake remained absent. Written informed consent for publication was obtained from the patient. This case highlights an important limitation of 18F-FDG PET/CT in detecting diffuse hepatic myeloma and emphasizes the need for multimodal diagnostic integration.
Approximately 0.1% of all prosthetic cardiac valves are affected by fungal endocarditis (bacterial endocarditis being the most common cause), which has a high case fatality rate. Post-treatment clinical improvement and a negative blood culture do not definitively rule out the presence of residual active disease. Among imaging techniques, trans-oesophageal echocardiography has higher sensitivity than transthoracic echocardiography, but has its own limitations. Functional imaging with 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/ CT) has shown to have high overall sensitivity, specificity, and accuracy for the diagnosis and follow-up evaluation of prosthetic valve infective endocarditis, thereby significantly influencing clinical management. Here, we report a rare case of a patient with Marfan syndrome and fungal prosthetic valve endocarditis, in which 18F-FDG-PET/CT played a significant role in management decision.
Prostate-specific membrane antigen (PSMA)-targeted radionuclide therapy has become an established treatment option for metastatic castration-resistant prostate cancer. Although lutetium-177 (177Lu) PSMA therapy has shown promising clinical benefits, terbium-161 (161Tb) PSMA is an emerging theranostic agent offering potential advantages due to its combination of beta and Auger electron emissions. This work presents the first documented case in Thailand and Southeast Asia of a patient treated at Ramathibodi Hospital with 161Tb-PSMA following progression on 177Lu-PSMA therapy. This report describes the clinical application of this novel radiopharmaceutical, the implementation of quantitative imaging protocols, single photon emission computed tomography/computed tomography calibration processes, and absorbed dose estimations from voxel-based dosimetry that contributed to individualised treatment planning.
Objectives:This study investigates the effects of high-dose radioactive iodine therapy on gonadotropin and sex hormone levels, and on sperm parameters in male patients with differentiated thyroid carcinoma following thyroidectomy. Methods:Twenty-five male patients (aged 20-60 years) with differentiated thyroid carcinoma underwent thyroidectomy and iodine therapy. The therapeutic dose was 150 mCi of oral sodium iodide solution. Levels of gonadotropins, sex hormones, and anti-Müllerian hormone (AMH) were measured before and two weeks after radioiodine therapy (RT). Semen analysis included liquefaction, odor, color, viscosity, agglutination, and aggregation. The main parameters evaluated were semen volume, pH, sperm count, percentages of motile and progressively motile sperm, round cells, and sperm morphology. Sperm motility, including progressive, non-progressive, and immotile types, and DNA fragmentation were analyzed according to World Health Organization guidelines. Results:The Wilcoxon signed-rank test was used with a significance level of p≤0.05. Follicle-stimulating hormone levels in patients' sera were significantly higher than pre-RIT measurements (p=0.002), whereas luteinizing hormone, dihydrotestosterone, dehydroepiandrosterone sulfate, testosterone, and AMH levels were not significantly different from pre-RT measurements. Total sperm count, volume, motility, and rapid progressive motility increased significantly compared to pre-radioiodine ablation measurements, while other parameters remained unchanged. Conclusion:Male patients who received 150 mCi of radioactive iodine showed no impairment in fertility. Long-term follow-up studies with larger sample sizes are crucial to investigate the physiological roles of gonadal hormones, sperm DNA fragmentation, and AMH in the testes after RIT.
