Nuclear Medicine Communications最新文献

Objective: In 2002 a UK audit was performed by the Nuclear Medicine Software Quality Group of filtered back projection (FBP) software, designed to evaluate the quantitative characteristics of single-photon emission computed tomography (SPECT). Subsequently, the use of FBP has reduced in common practice, with most guidelines now recommending and using iterative reconstruction. This study aimed to audit ordered-subset expectation-maximisation (OSEM) algorithms in clinical use, acting on the same input data.

Methods: A computational phantom was devised to evaluate the effect of sphere diameter, position and activity concentration along with an assessment of uniformity and resolution. Additional sections were implemented to evaluate the recovery in photopoenic areas and of small lesions adjacent to active structures. SPECT projections were created from the phantom and placed in the Digital Imaging and Communications in Medicine structures of acquired data from three SPECT camera manufacturers. Resultant projections were reconstructed via six commercial reconstruction platforms and quantitative measures from the above sections compared.

Results: Across all measures it was found that there was excellent agreement among platforms offering similar reconstruction methods. One platform was found to not offer the ability to perform a true 'pencil-beam' OSEM reconstruction and results varied with different manufacturer data supplied.

Conclusion: While there are differences in how reconstruction platforms process data from different manufacturers, these differences were generally small, with results from the one wide-beam reconstruction method having the largest variation. It would be advisable that users implementing sensitivity-based quantitative SPECT should derive factors for the various combinations of acquisition and reconstruction platforms at their disposal.

Objective: Development of companion diagnostics for targeted radionuclide therapy is critical, especially for full-size antibodies with prolonged circulation times. Engineering antibodies to modify their in-vivo pharmacokinetics, such as incorporating neonatal Fc receptor (FcRn)-binding mutations, can potentially enable earlier imaging timing and improved patient stratification. This study aimed to evaluate the impact of FcRn-binding mutations on the in-vitro binding characteristics and in-vivo biodistribution and imaging performance of a CD44v6-targeting full-size antibody, UU-40, labeled with different radionuclides, and to assess its potential as a companion diagnostic.

Methods: The study involved engineering UU-40 with LALA and IAHA mutations, evaluating specific binding, internalization, and affinity using in-vitro cell assays. Biodistribution and imaging studies [PET and single-photon emission computed tomography (SPECT)] were conducted in mice carrying human tumor xenografts in a dual-nuclide setting.

Results: The FcRn mutations (LALA/IAHA) did not affect antibody specificity or affinity, which was target-specific and affinity remained in the subnanomolar range. Biodistribution studies demonstrated that the residualizing radiometal label (177Lu) resulted in higher liver and spleen uptake compared with the nonresidualizing 125I-label, leading to reduced tumor-to-organ ratios. Tumor uptake was higher in A431 xenografts, with peak accumulation at 24 h postinjection. SPECT and PET imaging confirmed superior contrast at later time points (~24 h) with 125I-UU-40LALA/IAHA, while earlier imaging with 68Ga was hindered by increased nonspecific accumulation.

Conclusion: FcRn-binding mutations in full-size antibodies significantly alter their in-vivo pharmacokinetics without affecting binding affinity or specificity. Introducing these mutations enables earlier imaging time points, enhancing the potential for companion diagnostics in clinical settings.

Objective: The aim of this study is to analyze the dose-response relationship in hepatocellular carcinoma (HCC) patients who received transarterial radioembolization (TARE) with Y-90 resin microspheres.

Methods: Patients who received TARE with Y-90 resin microspheres using multicompartment dosimetry between February 2020 and December 2024 were included in the analysis. A total of 46 lesions from 21 patients were included in the dose-response analysis. Multicompartment dosimetry was performed for all lesions in the perfused area. Additionally, the mean tumor absorbed dose (TAD), whole-liver absorbed dose, and perfused-liver absorbed dose were calculated.

Results: All the patients received Y-90 resin microspheres with a lobar or segmental approach. Median tumor volume was calculated as 9.4 cm³ (min-max: 1-1674). During the third-month evaluation, 21 lesions were responders. In the receiver operating characteristic analysis, a 104 Gy cutoff for mean TAD [AUC: 0.693, 95% confidence interval (CI): 0.532-0.853, P  = 0.018] was calculated for response, with 76% sensitivity and 64% specificity. For the prediction of complete response, we found a 159 Gy cutoff for mean TAD (AUC: 0.776, 95% CI: 0.598-0.953, P  = 0.002), with 70% sensitivity and 79% specificity.

Conclusion: We demonstrated a strong relationship between absorbed tumor dose and treatment response in HCC patients who received TARE with Y-90 resin microspheres. Delivery of approximately 100 Gy mean absorbed dose to the tumor is needed to achieve a response. Increasing the TAD to ~160 Gy would be expected to result in a complete response.

Background: PET with 18 F-fluorodeoxyglucose ( 18 F-FDG) is widely used to evaluate inflammatory cardiac disorders such as sarcoidosis and myocarditis. However, physiologic myocardial uptake can obscure pathological uptake and must be suppressed.

Objective: To determine the effectiveness of fasting alone in suppressing physiological myocardial uptake and to establish a practical imaging protocol.

Methods: We retrospectively reviewed patients who underwent whole-body 18 F-FDG PET/CT for oncologic indications between January 2019 and December 2020. Patients were categorized by fasting duration: Group A (<12 h), Group B (12-17 h), and Group C (≥18 h). Two independent readers qualitatively graded myocardial FDG uptake, with adequate suppression defined as grade 0 (no uptake) or grade 1 (uptake ≤ liver background). Uptake above liver background (grade 2) was considered inadequate. Interreader agreement was assessed using Cohen's Kappa.

Results: A total of 450 patients were included (150 per group). Adequate myocardial suppression was achieved in 77.3, 66, and 60% of patients in Groups C, B, and A, respectively ( P = 0.005). Suppression was not associated with blood glucose, age, or diabetes. However, significant associations were observed with gender ( P = 0.024) and BMI ( P = 0.006). Interreader agreement was almost perfect (Cohen's Kappa 0.909; 95% CI: 0.868-0.950).

Conclusion: Fasting for ≥18 h is more effective than shorter durations in suppressing physiologic myocardial FDG uptake, enabling evaluation of myocardial inflammation. This simple and feasible protocol is particularly valuable in resource-limited settings. Visual grading demonstrated excellent reproducibility, supporting its role in clinical practice.

Cardiac amyloidosis (CA) is an emerging iceberg among the cardiomyopathies with significant morbidity and mortality. The overlapping signs and symptoms with other cardiac pathologies warrant prompt identification of the clinical red flags and imaging red flags (iRF) for early detection and treatment of CA. Unluckily data suggests that these patients visit 4-5 physicians before being diagnosed with CA; this is mainly due to perception of rarity, overlapping symptomatology with other common cardiac conditions (hypertension, chronic renal failure, aortic stenosis, and hypertrophic cardiomyopathy), and inability of identification of clinical and iRF of CA by the practicing physicians in the routine outpatient department (OPD) working. Recently published multiregional expert consensus on multimodality correlative cardiac imaging by international societies has emphasized on specific clinical and imaging red flags (iRF) using ECG, echocardiogram, 99m Tc-based scintigraphy, and cardiac MR for robust diagnosis of CA. However, reading all these tedious guidelines and retaining their diagnostic practice points (DPPs) appears difficult in daily practice for practicing physicians and residents. Therefore, the current draft has condensed and highlighted the DPPs of recent 5 years of published data in the form of concise, printable tables and flow charts, enabling a physician in the OPD to flick through, teach, and direct the suspected patients for prompt and timely diagnostic testing to rule out CA.

Objective: To investigate the advantages of high-normal-dose 18 F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) imaging in total-body PET/CT and short axial field-of-view (SAFOV) PET/CT systems.

Methods: This retrospective study initially included 137 patients underwent high-normal-dose (5.55 MBq/kg) 18 F-FDG PET/CT scans. 36 patients who underwent both total-body PET/CT and SAFOV PET/CT scans (G0) were included in the self-control cohort, while 101 patients who underwent only total-body PET/CT scans, formed the exploratory cohort. Total-body PET/CT scans were performed with a 5-min acquisition time, divided into multiple duration groups for the self-control cohort (30s-5 min), and for the exploratory cohort (1min- 5min). Objective image quality parameters included maximum standardized uptake value (SUV max ), mean standardized uptake value (SUV mean ), SD, and signal-to-noise ratio (SNR) of background issues. In addition, SUV max and tumor-to-background ratios were measured for the lesions. In the subsequent matched-pair study, 32 patients who underwent normal-dose 18 F-FDG (3.7 MBq/kg) SAFOV PET/CT (G780') were retrospectively matched with 32 subjects from the self-control cohort (G780).

Results: In the self-control cohort, SNR, SUV max , and tumor-to-background ratios were significantly higher in all total-body PET/CT groups compared with G0, with stable trends across the total-body PET/CT groups as acquisition time increased. In the exploratory cohort, G3'-G5' demonstrated better lesion detection rates than G1' and G2', but no significant differences were observed. In the matched-pair study, no significant differences were observed between G780 and G780'.

Conclusion: Compared with the normal-dose protocol, a high-normal dose offers minimal advantages in SAFOV PET/CT systems. Extended acquisition times enhance both objective image quality and lesion detection rates in total-body PET/CT, with optimal performance could reach at 3 min.

Gastric emptying scintigraphy (GES) is considered the gold standard test for gastroparesis (GP). The purpose of this systematic literature review is to establish what other tests exist for the diagnosis of GP in paediatrics. This is to aid clinical management of paediatric patients with suspected GP, who may not be able to tolerate gastric emptying studies or have access to nuclear medicine departments. Therefore, the following question is posed: 'Should gastric emptying scintigraphy studies be performed, as standard, on paediatric patients with suspected gastroparesis?' A comprehensive literature review was conducted using general library search and databases from the University of the West of England's library. Key themes were tabulated for reference and analysis. Papers were screened for relevancy. Thirteen papers were included in the final review. The review has shown that there are other tests, such as 13C-breath tests (13BT) and wireless motility capsule test (WMC), available to diagnose GP in paediatrics; however, it has also shown that these are limited by a lack of standardisation in how they are undertaken and reported. Although consensus recommendations for paediatric GES have now been released, these could be further developed and improved with the use of multicentre collaboration. 13BT and WMC tests could be more widely utilised, but are limited by a lack of standardisation and availability. Therefore, this review has found that until standardisation is achieved within the other tests, GES has become and remains the standard test to diagnose GP in the paediatric population.

Objectives: We evaluated the prognostic value of the new 18 F-fluorodeoxyglucose PET/computer tomography ( 18 F-FDG PET/CT) parameter reflecting the spread of the tumor, the largest distance between two lesions (Dmax), and compared the predictive power of the new parameter with other parameters in newly diagnosed multiple myeloma (NDMM) patients.

Methods: This retrospective study included 58 consecutive patients diagnosed with NDMM. 18 F-FDG parameters [maximum standardized uptake value, metabolic tumor volume (MTV), and Dmax] and clinical data were analyzed for event-free survival (EFS). Univariate and multivariate analyses were performed using the Cox proportional hazards model, while survival outcomes were assessed via Kaplan-Meier curves.

Results: The median length of follow-up was 42 months (interquartile range, 18-62 months). Univariate analysis identified elevated serum calcium, elevated serum creatinine, MTV > 102.54 cm 3 , Dmax > 0.44 m, Dmax normalized by body height (Dmaxbh) > 0.27, Dmax normalized by body surface area (Dmaxbsa) > 0.24 m -1 , and International Staging System stage as relevant prognostic factors for EFS ( P  < 0.1). Only Dmax > 0.44 m was found to be an independent prognostic factor for EFS on multivariate analysis ( P  = 0.047).

Conclusion: The new PET parameter of Dmax, reflecting myeloma dissemination, has been shown the independent prognostic value in NDMM patients. This preliminary finding warrants further investigation.

Intracardiac metastases from gastroenteropancreatic neuroendocrine tumors (NETs) are rare and challenging to diagnose. Lutetium (Lu)-177 DOTATATE therapy has demonstrated significant benefit in patients with metastatic NET; however, there are limited data regarding the direct impact on cardiac metastases. Patients with intracardiac metastasis from NET were evaluated. Patients were stratified by treatment with Lu-177 DOTATATE. Quantitative assessments of the progression of cardiac metastatic size (maximal diameter) and metabolic activity, as measured by maximal standardized uptake value (SUV max ), were performed on serial 68 Ga-DOTATATE PET imaging. In a cohort of 23 patients, 11 patients (47.8%) received Lu-177 DOTATATE therapy. Through a median of 2.2 years of follow-up, these patients showed some reduction in metastatic burden with a median reduction in maximal diameter of 1.0 mm (IQR: 0.0-3.0) and a median change in SUV max of -1.6 (IQR: -4.4 to 1.5). In contrast, patients who did not receive Lu-177 DOTATATE had some increase in maximal diameter of 0.5 mm (-2.0 to 2.0) and an increase in SUV max of 1.4 (-6.2 to 2.3). Overall, Lu-177 DOTATATE therapy may result in modest regression of intracardiac metastases as assessed by molecular imaging, whereas patients with cardiac metastases who did not receive therapy appeared to show progression.

Marine-Lenhart syndrome (MLS) is a rare variant of hyperthyroidism characterized by the coexistence of Graves' disease and autonomously functioning thyroid nodules. This comprehensive literature review aims to synthesize current knowledge regarding the pathophysiology, diagnostic approach, and management of MLS, with a particular focus on the role of nuclear medicine. A structured review of relevant literature-including clinical studies, case reports, and international guidelines-was conducted to explore thyroid anatomy, mechanisms of nodule formation, imaging findings, and therapeutic strategies. Thyroid scintigraphy using radiotracers such as 99m Tc-pertechnetate remains central to the diagnosis of MLS, enabling functional distinction between diffusely hyperactive tissue and coexisting nodules. Despite advances in ultrasonography and fine-needle aspiration biopsy, nuclear imaging continues to offer unique functional insights. Treatment typically involves antithyroid drugs and radioiodine (¹³¹I) therapy; however, higher radioiodine doses may be necessary due to the relative resistance of autonomously functioning nodules. Newer imaging modalities, such as ¹⁸F-fluorodeoxyglucose PET/computed tomography (CT), are not useful for primary nodule characterization but may detect incidental fluorodeoxyglucose-avid nodules that warrant further evaluation. MLS poses a diagnostic challenge due to its overlapping features with other thyroid disorders and the potential for malignancy within cold nodules. This review highlights the indispensable role of nuclear medicine in diagnosing and tailoring treatment for MLS, ultimately promoting better outcomes through precise functional assessment.