EJNMMI Research最新文献

Background: Dynamic two-dimensional (2D) planar renal scintigraphy is a widely used imaging modality for evaluating renal function, though its anatomical and quantitative accuracy is limited by overlapping structures. Recent advancements in single photon emission computed tomography/computed tomography (SPECT/CT) technology employ a multi-detector cadmium-zinc-telluride (CZT) ring configuration. This eliminates the need for camera rotation around the patient, reducing acquisition time and enabling high temporal resolution dynamic three-dimensional (3D) imaging. This technology may be particularly beneficial for kidney transplant patients.

Case presentation: We present a case of a 44-year-old male who underwent dynamic SPECT/CT renal scintigraphy with impaired urinary excretion following post kidney transplantation.

Conclusions: Dynamic SPECT/CT using a 3D-ring CZT-based camera demonstrated added diagnostic value in the presented renal scintigraphy application.

Background: Acidic pH values of the tumor microenvironment (TME) have crucial effects on metastatic behavior, host defense, immune regulation and cellular metabolism. Several studies have shown that the acidity of the interstitial space in the TME influences the functions of cancer and stromal cells, particularly regarding immune effects. Changing intratumoral pH might therefore be a potential target for therapy, and pH imaging might guide further developments. We describe radiopharmaceutical probes for positron emission tomography (PET) that exploit the concept of pH-dependent intratumoral hydrolysis of glycosylamine bonds of PET-tracers ([¹⁸F]FDG-4-methoxybenzylamine ([¹⁸F]FDG-4MBA) and [¹⁸F]FDG-benzylamine ([¹⁸F]FDG-BA)) to release [¹⁸F]FDG as functional moiety with the aim to non-invasively image pH changes.

Results: Nuclear magnetic resonance (NMR) spectroscopy demonstrated hydrolysis at pseudo first order and showed pH dependent hydrolysis time, at which 50% of [¹⁹F]FDG-4-methoxybenzylamine ([¹⁹F]FDG-4MBA) was cleaved, ranging from 3 h at pH 7.4 over 60 min at pH 6.9 to 45 min at pH 6.5. Hydrolysis of [¹⁸F]FDG-4MBA in human serum at pH 7,6 was similar to comparable pH without serum (below 10% FDG release after 2 h). The glycosylamines [¹⁸F]FDG-BA and [¹⁸F]FDG-4MBA were relatively stable in vitro at pH 8.3 with less than 15% FDG release from [¹⁸F]FDG-4MBA and less than 10% FDG release from [¹⁸F]FDG-BA within 60 min. Hydrolysis at acidic pH led to [¹⁸F]FDG release at pH 6.0 of 71% from [¹⁸F]FDG-4MBA and 40% from [¹⁸F]FDG-BA at 60 min. In vitro uptake into B16F10 or MC38 cells was pH dependent in contrast to FDG uptake. In a preclinical model bearing the two different acidic subcutaneous tumors (B16F10 and MC38), pH differences in the acidic TME were better discriminated with [¹⁸F]FDG-4MBA than with [¹⁸F]FDG-BA. In vivo neutralization of the acidic extracellular tumor pH prevented pH-dependent cleavage of [¹⁸F]FDG-4MBA resulting in decrease of PET signal.

Conclusion: The determination of pH differences by glycosylamines radiotracers and PET imaging in acidic TME may serve as a novel marker for various questions such as interaction of pH regulation and response to immunotherapies. Notably, even small pH differences in the acidic TME of different tumors, in the same in vivo model, could be discriminated.

Background: Follicular lymphoma (FL), as the most common indolent lymphoma, exhibits reduced survival rates in patients with early progression compared to those without early progression. We aimed to develop a scoring system integrating baseline ¹⁸F-FDG PET/CT tumor metabolic parameters with clinical and other relevant factors to personalize the prediction of disease progression within 24 months (POD24) in FL patients.

Results: Among 123 patients with FL, 33 (26.8%) experienced disease progression within 24 months of follow-up. Among clinical indicators, Lactate dehydrogenase (LDH) [OR: 3.267 (1.055, 10.117), P = 0.040] was an independent risk factor for POD24. Based on the receiver operating characteristic (ROC) curve, the optimal cutoff values for Total lesion glycolysis (TLG), total metabolic tumor volume (TMTV), maximum distance of spread (Dmax), and voxel-based maximum interlesion distance (DmaxVox) in POD24 patients were 628.59 g, 94.08 cm³, 37.22 cm, and 77.92 cm, respectively. Additionally, TLG > 628.59 g [OR: 5.1430 (1.9360, 13.6580), P = 0.001], TMTV > 94.08 cm³ [OR: 11.8530 (2.6730, 52.5640), P = 0.001], Dmax > 37.22 cm [OR: 3.0000 (1.1880, 8.6878), P = 0.028], and DmaxVox > 77.92 cm [OR: 8.0620 (2.2830, 28.4720), P = 0.001] were all risk factors for POD24 patients. The correlation heatmap revealed significant positive correlations between TLG and TMTV (r = 0.95) and between Dmax and DmaxVox (r = 0.99). Patients were stratified into three risk groups based on clinical LDH and imaging parameters TMTV and DmaxVox, with POD24 incidence rates of 5.7%, 26.1%, and 57.1%, respectively (P < 0.001). The constructed integrated model demonstrated the highest predictive performance for POD24 (AUC = 0.759). Decision curve analysis (DCA) and calibration curves confirmed the model's robust predictive capability.

Conclusions: TMTV and DmaxVox on baseline ¹⁸F-FDG PET/CT imaging, along with the clinical parameter LDH, are independent predictors of early disease progression within 24 months (POD24) in patients with FL. A predictive model combining these imaging metrics with clinical parameters effectively stratifies patient risk.