An initial study on the comparison of diagnostic performance of 18F-FDG PET/MR and 18F-FDG PET/CT for thoracic staging of non-small cell lung cancer: Focus on pleural invasion.

OBJECTIVE: To compare the diagnostic performance of 18F-FDG PET/MR and PET/CT preliminarily for the thoracic staging of non-small cell lung cancer (NSCLC) with a special focus on pleural invasion evaluation. METHODS: 52 patients with pathologically confirmed NSCLC were included and followed for another year. Whole-body 18F-FDG PET/CT and subsequent thoracic PET/MR were performed for initial thoracic staging. Thoracic (simultaneous) PET/MR acquired PET images and MRI sequences including T2 weighted imaging, with and without fat saturation, T1 weighted imaging, and diffusion weighted imaging (DWI). Two radiologists independently assessed the thoracic T, N staging and pleural involvement. The McNemar Chi-square test was used to compare the differences between PET/CT and PET/MR in the criteria. The area under the receiver-operating-characteristic curves (AUC) was calculated. RESULTS: Compared to PET/CT, PET/MR exhibited higher sensitivity, specificity in the detection of pleural invasion; 82 % vs. 64% (p = 0.625), 98 % vs. 95% (p = 1.000), PET/MR to PET/CT respectively. The receiver-operating-characteristic analysis results of PET/CT vs PET/MR for the pleural invasion were as follow: AUCPET/CT = 0.79, AUCPET/MR = 0.90, p = 0.21. Both T staging results and N staging results were approximately identical in PET/CT and PET/MR. Differences between PET/CT and PET/MR in T staging, N staging as well as pleural invasion accuracy were not statistically significant (p > 0.05, each). CONCLUSION: PET/MR and PET/CT demonstrated equivalent performance about the evaluation of preoperative thoracic staging of NSCLC patients. PET/MR may have greater potential in pleural invasion evaluation for NSCLC, especially for solid nodules, crucial to clinical decision-making, though our results did not demonstrate statistical significance.

Tracking Neural Stem Cells in vivo: Achievements and Limitations.

Neural stem cell (NSC) therapies are developing rapidly and have been proposed as a treatment option for various neurological diseases, such as stroke, Parkinson's disease and multiple sclerosis. However, monitoring transplanted NSCs, exploring their location and migration, and evaluating their efficacy and safety have all become serious and important issues. Two main problems in tracking NSCs have been noted: labeling them for visibility and imaging them. Direct labeling and reporter gene labeling are the two main methods for labeling stem cells. Magnetic resonance imaging and nuclear imaging, including positron emission tomography, single-photon emission computed tomography, and optical imaging, are the most commonly used imaging techniques. Each has its strengths and weaknesses. Thus, multimodal imaging, which combines two or more imaging methods to complement the advantages and disadvantages of each, has garnered increased attention. Advances in image fusion and nanotechnology, as well as the exploration of new tracers and new imaging modalities have substantially facilitated the development of NSC tracking technology. However, the safety issues related to tracking and long-term tracking of cell viability are still challenges. In this review, we discuss the merits and defects of different labeling and imaging methods, as well as recent advances, challenges and prospects in NSC tracking.

The image quality, lesion detectability, and acquisition time of 18F-FDG total-body PET/CT in oncological patients.

PURPOSE: The purpose was to investigate the effects of short acquisition time on the image quality and the lesion detectability of oncological 18F-FDG total-body PET/CT. METHODS: Nineteen oncological patients (6/13 women/men, age 65.6 ± 9.4 years) underwent total-body PET/CT on uEXPLORER scanner using 3D list mode. The administration of 18F-FDG was weight-based (4.4 MBq/kg). The acquisition time was 900 s, and PET data were reconstructed into 900-, 180-, 120-, 60-, 30-, and 18-s duration groups. The subjective PET image quality was scored using a 5-point scale (5, excellent; 1, poor) in 3 perspectives: overall quality, noise, and lesion conspicuity. The objective image quality was evaluated by SUVmax and standard deviation (SD) of the liver, SUVmax of the tumor, and tumor-to-background ratio (TBR). The lesion detectability was the percentage of identifiable lesions in the groups of 180 to 18 s using the group 900 s as reference. RESULTS: Our results showed that sufficient and acceptable subjective image quality could be achieved with 60- and 30-s groups, and good image quality scores were given to 180- and 120-s groups without significant difference. For shortened acquisition time, SD was increased, while SUVmax of tumor and TBR remained unchanged. The lesion detectability was decreased with shorter acquisition time, but the detection performance could be maintained until the 60-s group compared with the 900-s group, although the image quality degraded. CONCLUSION: The total-body PET/CT can significantly shorten the acquisition time with maintained lesion detectability and image quality.