Molecular Imaging and Radionuclide Therapy最新文献

We describe a case of a 57-year-old woman with isolated immunoglobulin G4-related disorder affecting her lacrimal glands. Pre-treatment ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) showed diffuse enlargement and increased FDG uptake in both lacrimal glands. After immunosuppressive treatment, ¹⁸F-FDG PET/CT showed no significant FDG uptake, and the sizes of both glands returned to normal.

Lung cancer is the leading cause of cancer-related deaths worldwide. While metastasis to distant organs is commonly described, renal metastasis remains rare and uncommon. In this paper, we present the case of a 53-year-old man with a history of left apical lung adenocarcinoma who underwent fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (CT) for suspected recurrence. The scan revealed a recurrent pulmonary mass with metastatic spread, notably showing intense bilateral focal FDG uptake in the kidneys. A metastatic origin was suspected and subsequently confirmed by CT-guided renal biopsy. Although rare and typically observed in advanced stages of the disease, this case underscores the importance of carefully evaluating focal FDG uptake in the renal cortex to ensure accurate staging and optimal management of oncologic patients.

Objectives: A Iodine-131 (¹³¹I) whole body scan (WBS) is performed to evaluate the treatment response after radioactive iodine (RAI) therapy. Despite the clinical relevance of RAI-refractory differentiated thyroid cancer, a consensus on its precise definition remains lacking. This study investigates the potential utility of hepatic ¹³¹I accumulation as an early predictor for tumor recurrence or progression after RAI administration.

Methods: Of 814 patients receiving care at our institution, we enrolled 225 patients who exhibited no accumulation of RAI in the remnant tissues or other lesions on ¹³¹I WBS. We quantified the hepatic uptake ratio [defined as (hepatic uptake/background uptake (H/B)] from WBS. All patients were categorized into group A (H/B ≤1.5) and group B (H/B >1.5), and we assessed between-group differences. The Kaplan-Meier method and Log-rank test were used to analyze the progression-free survival (PFS). Using the Cox proportional hazards model, we identified independent prognostic factors from among the seven known prognostic factors, i.e., H/B, thyroglobulin, sex, age, stage, total ¹³¹I dose, and final therapeutic dose.

Results: The 5-year and median PFS were 98.8% and 114.7 months in group A (n: 171) compared with 24.1% and 42.7% months in group B (n: 54), respectively. Group B showed a significant correlation with poor prognosis (p<0.00001). Of the seven prognostic factors, H/B exhibited the highest impact on patient outcomes (hazards ratio for recurrence/disease progression, 42.156; 95% confidence interval: 8.750-203.106).

Conclusion: Quantitative evaluation of hepatic uptake on ¹³¹I WBS provides a marker that may help identify patients with differentiated thyroid cancer who are at a high risk of disease progression/recurrence immediately after RAI therapy.

Objectives: To investigate the relationship between radiation dose, metabolic changes in the salivary glands assessed by ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT), and xerostomia severity in patients with head and neck cancer following radiotherapy (RT).

Methods: We retrospectively analyzed 107 patients treated with intensity-modulated RT or volumetric modulated arc therapy for head and neck malignancies. Clinical xerostomia severity was evaluated at the time of post-treatment PET/CT. Mean gland doses and dose-volume parameters (V10-V50) were extracted from treatment plans. Metabolic changes were evaluated by ^Δmaximum standardized uptake value and ^Δmean standardized uptake value between pre and post treatment PET/CT scans. The relationships between clinical, dosimetric, and metabolic variables were examined.

Results: Moderate-to-severe xerostomia occurred in 63.6% of patients. Both higher T and N stage were significantly associated with greater xerostomia severity (p<0.05). Patients with nodal metastases on pretreatment PET/CT demonstrated a higher prevalence of xerostomia. Dose-volume parameters (V10-V30 for parotids, V50 for submandibular glands) were significantly correlated with symptom severity. ^ΔSUV values were significantly associated with both mean dose and dose-volume parameters, particularly in the left parotid gland, where patients receiving >30 Gy showed markedly greater metabolic decline. Parotid glands demonstrated stronger dose-dependent metabolic changes compared with submandibular glands, consistent with their higher radiosensitivity.

Conclusion: Despite the use of advanced RT techniques, xerostomia remains a frequent toxicity. ¹⁸F-FDG PET/CT reliably captured dose-dependent salivary gland impairment and reflected the impact of tumor burden on toxicity risk. These findings underscore the complementary role of PET-derived biomarkers as integrative tools for predicting salivary dysfunction beyond conventional dosimetric parameters.

We report the case of a 56-year-old female recently diagnosed with well-differentiated squamous cell carcinoma of the external auditory canal. The patient underwent an 18F-fluorodeoxyglucose positron emission tomography/computed tomography for staging assessment. This examination revealed intense uptake in the right ear canals, tympanic cavity, eustachian canal, parapharyngeal area, and infratemporal fossa. Notably, we identified intracranial dural metastasis, which represents an uncommon site for metastatic spread in general.

A 74-year-old man with a history of prostate cancer and rising prostate-specific antigen underwent ¹⁸F-prostate specific membrane antigen PSMA)-1007 positron emission tomography/computed tomography for investigation of oligometastatic disease. There was evidence of PSMA avid local recurrence findings with pelvic and retroperitoneal nodal metastases and skeletal deposits. Although rare and could easily be mistaken for contamination, a small penile metastasis was found. This is associated with poor prognosis and could impact further management. This case highlights the importance of a detailed review of the penis, to ensure differentiation between urinary activity and pathological uptake.

Objectives: Yttrium-90 (⁹⁰Y) radioembolization has become increasingly important in the treatment of liver tumors. This study aims to experimentally determine the extent to which small liver tumors are affected by the partial volume effect (PVE) in single photon emission computed tomography/computed tomography (SPECT/CT) scintigraphy using technetium-99m-macroaggregated albumin (Tc-99m-MAA), and to investigate the impact of PVE on tumor dosimetry and image quality.

Methods: In this experimental study, a custom-designed liver phantom containing four tumor mimics with diameters of 1 cm, 2 cm, 3 cm, and 5 cm was used. The tumor and liver parenchyma volumes were filled with Tc-99m at a ratio of 4.86: 1. The phantom was imaged in a water tank using SPECT/CT according to standard clinical protocols. Volumetric regions of interest were drawn for each lesion and tumor volumes, contrast values (C), contrast to noise ratios (CNR), and absorbed tumor doses were calculated from the counts obtained. Since this study does not involve live subjects and was conducted solely on a phantom model, ethical approval, informed consent, and consent forms are not required for this study.

Results: Tumor diameters measured on SPECT/CT images matched those obtained from both CT images and the actual dimensions. The contrast values calculated from the SPECT/CT images for lesions with diameters of 2 cm and 5 cm were 2.03 and 3.89, respectively. Similarly, the corresponding CNR values were 8.64 and 21.07. Tumor-to-normal tissue ratios were 2.03 and 3.89 for the 2 cm and 5 cm lesions, respectively. For the 2 cm lesion, the actual and SPECT/CT-derived absorbed doses were 15.3 Gy and 7.87 Gy, respectively. For the 5 cm lesion, these values were 15.4 Gy and 13.38 Gy, respectively. The absorbed tumor doses significantly decreased as tumor diameter decreased due to the influence of PVE.

Conclusion: Tumors smaller than 2 cm in diameter were markedly affected by the PVE. Considering the influence of PVE, or applying appropriate corrections in dosimetric calculations, is of critical importance for improving the accuracy of dosimetry results.

Objectives: Contralateral lung parenchymal metastasis (CLM), less common than expected in lung cancer, and its exact mechanism is still unknown. To determine the additional value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in determining CLM, its causes, and predictive factors in lung cancer.

Methods: The data were evaluated by comparing the group with CLM and the group without CLM but with distant metastasis to other organs, two groups known as the M1 classification according to the 9^th tumor-node-metastasis classification in lung cancer. Histopathological data, follow-up, and ¹⁸F-FDG PET/CT findings, including primary tumor lobe, segment, size, pleural effusion, additional metastasis, and their maximum standardized uptake value (SUV_max) values were recorded, and survival analyses were performed.

Results: CLM developed in 125 cases. Eighty-one individuals had contralateral metastases at diagnosis, and 44 developed CLM during follow-up. Distant metastases were present in 100 patients; there was no CLM in the control group. While there was no statistical difference between the two groups in terms of the SUV_max, mean standardized uptake, and metabolic tumor volume values, the presence of satellite nodules and metastatic nodules in other lobes in the same lung were found to be significantly higher in the CLM group (p=0.007; p<0.001). Also, in the CLM group, ipsilateral nodules had significantly higher SUV values than the control group (3.47 g/mL in the CLM group vs 2.81 g/mL in the control group; p=0.046). Pleural metastasis and effusion were more common in the CLM group (p=0.003; p=0.036). The mean SUV values in pleural metastases and pleural effusions in the CLM group were statistically significantly higher (p=0.048 and p=0.037). In statistical analyses, satellite nodules increase the probability of CLM fourfold, while ipsilateral other lobe nodules in the same lung increase it by 5.527 times (p=0.012; R=-0.2752 and p=0.005; R=-0.3672). Additionally, the absence of necrosis in the initial tumor raises the probability of metastasis to the contralateral lung by 3.326 times during follow-up (p=0.015; R=0.2656).

Conclusion: The study emphasized the role of ipsilateral nodules, pleural effusion, and pleural metastasis in predicting CLM using ¹⁸F-FDG PET/CT imaging.

A 56-year-old male patient underwent total thyroidectomy, and pathology revealed multicentric papillary thyroid cancer. His post-operative stimulated thyroglobulin value was >500 ng/mL. ¹⁸F-fluorodeoxyglucose positron emission tomography (PET) computed tomography revealed hypermetabolic metastatic pulmonary nodules, cervical, and mediastinal lymph nodes. There was also a hypermetabolic lesion in the left gluteal muscle. Due to the patient's history of a pilonidal cyst in the same region, the possibility of an abscess was also considered, and due to the absence of radioactive iodine (RAI) uptake in the lesion, follow-up was deemed appropriate. During follow-up, as the patient progressed to RAI-refractory state, ⁶⁸Ga-DOTATATE PET/magnetic resonance imaging, which was done for radionuclide therapy planning, revealed heterogeneously increased uptake in the gluteal lesion. A subsequent biopsy confirmed the diagnosis of PTC metastasis.