Diffuse Gallium-67 Accumulation in the Left Atrial Wall Detected Using SPECT/CT Fusion Images

Production of 68Ge, 68Ga, 67Ga, 65Zn, and 64Cu important radionuclides for medical applications: theoretical model predictions for α-particles with 66Zn at ≈10–40 MeV

Theoretical predictions were made using TALYS-1.95(G) and EMPIRE 3.2 reaction-model codes for 69Ge, 67Ge, and medically used 68Ge, 67Ga, 68Ga, 65Zn, 64Cu radionuclides produced in the interaction of α-projectile with 66Zn-target at 10–40 MeV α-energies. Pearson’s statistical coefficients showed moderate to strong positive correlations between the theoretically predicted and experimentally measured production cross sections for radionuclides with practical medical applications. Furthermore, the present results indicated that a medium-sized cyclotron and a single α + 66Zn system (projectile + target system) might be an option for optimized production of 68Ge, 68Ga, 67Ga, 65Zn, and 64Cu radionuclides.

Effects of chronic immobilization stress on biokinetics and dosimetry of 67Ga in a murine model

The aim of this work is to determine the effect of chronic immobilization stress on kinetics and dosimetry of ⁶⁷Ga in a mouse model. A control group (CG) and a stress group (SG), each with 15 mice, were included in the study, and the latter group was subjected to a chronic immobilization stress model 2 h daily for 14 consecutive days. At day 13, ⁶⁷Ga-citrate was administered intraperitoneally (11.24 ± 0.44 MBq) to each mouse. Then, sets of three mice were obtained sequentially at 24, 36, 48, 60 and 72 h, in which the radionuclide activity was measured with an activity counter. The ⁶⁷Ga biokinetic data showed a fast blood clearance in the SG, with a mean residence time of 0.06 h. The calculated mean radiation absorbed doses were: liver (2.45 × 10^-03 Gy), heart (3.17 × 10^-04 Gy) and kidney (1.88 × 10^-04 Gy) in the SG. The results show that stress reduced weight gain by approximately 13% and also increased adrenal gland weight by 26%. On the other hand, chronic stress accelerates ⁶⁷Ga clearance after 24 h compared to normal conditions. It is concluded that murine organisms under chronic immobilization stress have higher gallium-67 clearance rates, decreasing the cumulated activity and absorbed dose in all organs.

Diagnostic Efficacy of Cardiac Scintigraphy with 99mTc-Pyrophosphate for Latent Myocardial Inflammation in Patients with Atrial Fibrillation

Objectives

This work aimed to study the efficacy of hybrid ^99mTc-Pyrophosphate SPECT/CT for diagnosis of latent inflammatory processes in the myocardium of patients with atrial fibrillation (AF).

Methods

The study comprised 34 patients aged 44 ± 9 years with AF of unknown etiology referred for radiofrequency ablation. The data were acquired using hybrid ^99mTc-Pyrophosphate SPECT/CT. To evaluate and interpret the results of hybrid study and to determine localization of radiopharmaceutical accumulation, scintigraphic and CT images were fused. SPECT/CT results were compared with data of endomyocardial biopsy.

Results

Sensitivity, specificity, and accuracy of ^99mTc-Pyrophosphate SPECT/CT in diagnosing myocarditis were 91%, 100%, and 94%, respectively. Proposed diagnostic criteria for myocarditis comprised intensity of the radiopharmaceutical accumulation in the myocardium and the ratios of focus/lung, focus/vertebral column, and focus/LV pool. Minimum cutoff values for the histologically verified myocarditis were >1.47 for focus/lung index, >0.11 for focus/vertebral column ratio, and >1.26 for focus/lung index.

Conclusions

SPECT/CT-based quantitative assessment of ^99mTc-Pyrophosphate accumulation in the myocardium is a highly informative noninvasive method for diagnosis of inflammatory process in the heart in patients with AF of undefined etiology.