EJNMMI Research最新文献

Background: Graves' ophthalmopathy (GO) is a challenging autoimmune manifestation of Graves' disease, whose management relies on accurate assessment of inflammatory activity in the extraocular muscles (EOMs). The Clinical Activity Score (CAS), the current gold standard for assessing disease activity, is based on subjective clinical signs. Consequently, objective imaging biomarkers are urgently needed as a complement orbital ^99mTc-DTPA SPECT/CT imaging holds potential, but its quantitative methodology lacks standardization. This study aimed to evaluate the utility of four SPECT/CT-derived quantitative indices for quantifying EOM inflammatory activity in GO.

Results: Group Differences: EOM uptake values for all four indices were significantly higher in the active GO group than in both the inactive and control groups (all P ＜ 0.001). No significant differences were found between the inactive and control groups.

Clinical correlation: All quantitative parameters showed significant positive correlations with the CAS (all p ＜ 0.001).

Diagnostic performance: ROC curve analysis confirmed that all indices effectively differentiated active from inactive GO, with SUV_mean yielding the superior diagnostic efficacy (AUC = 0.887).

Conclusions: In summary, this study confirms that quantitative indices from orbital ^99mTc-DTPA SPECT/CT, particularly SUV_mean-3D, effectively quantify EOMs inflammatory activity in GO. Parameters derived using CT-based 3D VOI delineation (SUV_mean-3D and SUV_max-3D) demonstrated superior reliability over traditional methods. Among all indices, SUV_mean-3D demonstrated superior diagnostic efficacy (AUC = 0.887) for differentiating active from inactive disease. These indices provide an objective tool for quantifying GO severity and monitoring disease changes during patient follow-up. This capability is vital for monitoring treatment response, guiding therapeutic decisions, and serving as a potential endpoint in clinical trials.

Background: [¹⁸F]F-FDG PET/CT is an established imaging modality for diagnosing cardiac sarcoidosis (CS). While a 90-minute uptake time is commonly recommended to enhance target-to-background ratio, its added diagnostic value remains unclear. This study aimed to compare the diagnostic performance of 60-minute versus 90-minute uptake times. Eighty-seven patients (45 females, 42 males) with suspected CS underwent whole-body FDG PET/CT at 60 min post-injection (p.i.), followed by an additional chest scan at 90 min p.i. Patient preparation included a low-carbohydrate diet, prolonged fasting, and weight-based heparin administration. Three blinded readers with varying experience independently assessed the scans using binary classification for typical sarcoidosis-related FDG uptake, provided adequate myocardial glucose suppression was achieved. Inter- and intrarater agreement were analyzed using Fleiss' and Cohen's κ, respectively. Diagnostic accuracy was determined by majority vote, using Japanese Circulation Society (JCS) criteria as the reference standard.

Results: Interrater agreement was substantial (Fleiss' κ = 0.690-0.693), and intrarater agreement ranged from substantial to almost perfect (Cohen's κ = 0.703-0.899). Among patients with sufficient myocardial suppression, diagnostic accuracy was 97% (n = 62) at 60 min and 92% (n = 65) at 90 min. No statistically significant differences were observed between the two time points (p = 0.22).

Conclusion: FDG PET/CT with a 60-minute uptake time offers diagnostic accuracy comparable to that of a 90-minute uptake for CS detection, provided adequate myocardial suppression is achieved. Shorter uptake protocols may streamline workflow and improve patient comfort without compromising diagnostic integrity.

Background: Hyperparathyroidism-jaw tumor (HPT-JT) syndrome is a rare autosomal dominant disorder caused by CDC73 gene mutations, predisposing individuals to primary hyperparathyroidism (pHPT), cemento-ossifying fibromas, and other neoplastic conditions. [18F]Fluorocholine PET/CT has emerged as a tool for localizing hyperfunctioning parathyroid glands in pHPT, but its application in HPT-JT syndrome remains unreported.

Case presentation: We describe the case of a 15-year-old male presenting with severe hypercalcemia, increased PTH serum levels, and a history of cemento-ossifying fibroma removal. Standard imaging, including [99mTc]Tc-MIBI scintigraphy, was inconclusive. [18F]Fluorocholine PET/CT successfully identified a hyperfunctioning parathyroid gland, identified as parathyroid atypical adenoma at subsequent histology, and a recurrent maxillary cemento-ossifying fibroma. Genetic testing confirmed a CDC73 mutation, leading to the diagnosis of HPT-JT syndrome.

Conclusions: To our knowledge, this is the first reported case utilizing [18F]Fluorocholine PET/CT for the evaluation and management of HPT-JT syndrome with active presence of a maxillary cemento-ossifying fibroma. Given its superior sensitivity compared to conventional imaging, [18F]Fluorocholine PET/CT provided critical information for surgical planning and it might be a useful diagnostic tool for long-term disease monitoring. This case highlights the potential role of [18F]Fluorocholine PET/CT in detecting both parathyroid and jaw manifestations of HPT-JT syndrome, emphasizing the need for further research into its application in hereditary endocrine disorders.

Background: Terbium-161 (Tb-161) emits internal conversion and Auger electrons, in addition to beta-minus radiation, which might be of added benefit for targeted radionuclide therapy (TRT) compared to Lutetium-177 (Lu-177). We extensively compared Lu-177 and Tb-161 for fibroblast activation protein (FAP)- TRT in a preclinical setting. To study this, FAP-2286 was labeled with Lu-177 and Tb-161 and characterized in vitro on FAP-expressing cells and ex vivo using patient tumor samples. Moreover, in vivo studies (i.e. biodistribution and efficacy) were performed using a clinically representative pancreatic ductal adenocarcinoma (PDAC) mouse model. Biodistribution was performed 1, 4, 24, and 48 h post injection of 5 MBq/500 pmol [¹⁷⁷Lu]Lu-FAP-2286 or [¹⁶¹Tb]Tb-FAP-2286. Subsequently, animals were treated with 4 × 40 MBq/500 pmol [¹⁷⁷Lu]Lu-FAP-2286 or [¹⁶¹Tb]Tb-FAP-2286 and with alternating doses of 2 × 40 MBq/500 pmol of each radiopharmaceutical.

Results: No difference in [¹⁷⁷Lu]Lu-FAP-2286 and [¹⁶¹Tb]Tb-FAP-2286 uptake was observed in the cell models. In vivo studies did not show a survival benefit of 4 × 40 MBq/500 pmol [¹⁷⁷Lu]Lu-FAP-2286 or [¹⁶¹Tb]Tb-FAP-2286, while Kaplan-Meier analyses demonstrated a modest prolonged survival after tandem therapy in mice that first received [¹⁷⁷Lu]Lu-FAP-2286 followed by [¹⁶¹Tb]Tb-FAP-2286. Dosimetry calculations based on autoradiography studies on patient tumor samples showed that even with lower binding, a higher absorbed dose to the tumor can be accomplished with [¹⁶¹Tb]Tb-FAP-2286.

Conclusions: In our in vitro and in vivo studies, [¹⁷⁷Lu]Lu-FAP-2286 and [¹⁶¹Tb]Tb-FAP-2286 demonstrated similar behavior. In the applied PDAC mouse model, FAP-TRT showed limited therapeutic efficacy, most likely due to the limited radiopharmaceutical uptake observed in the tumors. This hampered determination of a potential benefit of either radioisotope for FAP-TRT. Of note, a modest response was observed in the tandem therapy group that first received [¹⁷⁷Lu]Lu-FAP-2286, followed by [¹⁶¹Tb]Tb-FAP-2286.