Heterogeneous Uptake of 68 Ga-DOTATATE and 18 F-FDG in Initial Diagnosed Neuroendocrine Tumors Patients : Which Patients Are Suitable for Dual-Tracer PET Imaging?

PURPOSE

This study was designed to assess the uptake heterogeneity in neuroendocrine tumor (NET) patients at initial diagnosis with dual-tracer PET imaging and the staging changes and prognostic value it brings to explore the indication of the use of dual-tracer PET.

METHODS

Fifty-one newly diagnosed patients with pathologically confirmed NET who underwent 18 F-FDG and 68 Ga-DOTATATE PET imaging between January 2020 and September 2022 were enrolled. Dual-tracer uptake patterns were classified into 3 groups: A. 68 Ga-DOTATATE positive and 18 F-FDG negative, B. 68 Ga-DOTATATE positive and 18 F-FDG positive, and C. 68 Ga-DOTATATE negative and 18 F-FDG positive. Descriptive statistics were used to evaluate the heterogeneity of dual-tracer uptake patterns among different grading (G) groups, between primary and metastatic lesions, and staging changes. Moreover, dual-tracer uptake patterns, grade, age, sex, and stage were compared with progression-free survival (PFS) by Cox regression.

RESULTS

In the different G groups, none of the patients with dual-tracer uptake pattern A had grade 3 histology, but 57% of patients with grade 1 disease had FDG avidity (25% of them resulting in dual-tracer uptake pattern C). Patients with no metastasis were well differentiated, but one of them presented with dual-tracer uptake pattern C. Different uptake patterns were also observed between primary and metastatic lesions, particularly 44% of patients with dual-tracer uptake pattern A of primary with FDG avidity of metastases. Moreover, 9 (17.6%) had new lesions detected by additional 18 F-FDG PET imaging, and 3 of them (5.9%) had clinical stage changed accordingly. The Cox regression test showed that the dual-tracer uptake patterns were significantly correlated with PFS by univariate and multivariate analyses ( P = 0.026 and 0.039, respectively), whereas the grade and stage did not correlate with survival (all P >0.05).

CONCLUSION

The current study has proven the uptake heterogeneity of the NET at initial diagnosis and demonstrated the staging and prognostic value of dual-tracer PET imaging. Our preliminary results have confirmed the importance of dual-tracer imaging modalities and concluded that dual-tracer PET imaging could be considered as prognostic tool for all patients with an initial diagnosis of NET.

Double contrast-enhanced ultrasonography of a small intestinal neuroendocrine tumor: a case report of a recommendable imaging modality

A 57-year-old male presenting with spontaneously relieved abdominal cramp and distension was admitted to the West China Hospital. The diagnosis remained unclear after colonoscopy and computed tomography. Double contrast-enhanced ultrasonography was then performed and a neoplasm in the small intestine was suspected, supported by a thin-section computed tomography and positron emission tomography/computed tomography. This was confirmed pathologically after surgery to be a small intestinal G1 neuroendocrine tumor. Surgery was performed to remove approximately 25 cm of small bowel and a 3-cm solid mass located in the mesentery. The patient had a complete recovery and was tumor-free at the final follow-up. Small intestinal tumors including neuroendocrine tumors have always posed a diagnostic challenge. This case indicated that double contrast-enhanced ultrasonography is feasible in detection of small intestinal neuroendocrine tumors, and it may be an advisable approach assisting diagnosis of small intestinal tumors.

[The Application Value of True Whole-body PET/CT Scanning Protocol in Patients of Extranodal NK/T Cell Lymphoma]

Objective

To assess the staging, restaging, and treatment strategy determination of extranodal NK/T cell lymphoma (ENKT) by PET/CT real body (true whole-body, TWB) imaging, which is superior to PET/CT limitation of the whole body (limited whole-body, LWB, from skull vertex to upper thighs) by adding 'distal lower extremity' images.

Methods

TWB ¹⁸F-FDG PET/CT studies performed for staging and follow-up of ENKTL patients between January 2012 and September 2017 were retrospectively reviewed. Patients in staging group received TWB PET/CT evaluation for staging at the first diagnosis. In follow-up group, patients received follow-up evalution with TWB PET/CT and progressive disease (PD) in the LWB range with or without clinical diagnosis or suspicion before follow-up examination, and then divided into four subgroups: staging (+) PD (－), staging (+) PD (+), staging (－) PD (－), staging (－) PD (+). Then the percentage of unexpected ENKTL lesions found at the distal extremity (outside the LWB range) (P1), and the percentage of changes in the staging, restaging/outcome evaluation (P2) in each group were recorded.

Results

Among the 225 patients in the staging group, 200 (88.9%) had tumors confined to LWB, while P1 was 11.1% (25 cases) and P2 was 0.4% (1 case). In the follow-up group, the P1 in staging (+) PD (－)( n=85), staging (+) PD (+)( n=4), staging (－) PD (－)( n=43), staging (－) PD (+) goups ( n=15) were 1.2%, 75.0%, 0%, 26.7%, and P2 were 1.2%, 0%, 0%, 13.3%, respectively. In the follow-up group, regardless of whether the TWB PET/CT examination was performed at the initial diagnosis stage, P1 in PD (－) group and PD (+) group was 0.8 vs. 36.8% ( P<0.000 1), and P2 was 0.8% vs. 10.5% ( P<0.000 1).

Conclusion

It is not recommended that the TWB PET/CT imaging from the top of the head to the bottom of the foot use for the first diagnosis of ENKTL patients. And for follow-up patients with no clinical evidence of tumor progression or with evidence of tumor progression but whose lesions were limited to LWB at the initial diagnosis of TWB PET/CT staging, LWB PET/CT from the top of the head to the middle of the thigh is recommended for routine follow-up. For ENKTL patients, TWB PET/CT was not performed at the initial stage of diagnosis to detect the condition of lower limbs. If the evidence of tumor progression in the LWB range appeared before the follow-up examination, TWB PET/CT was recommended for the follow-up evaluation to evaluate the systemic tumor involvement.

Evolution analysis of EUV radiation from laser-produced tin plasmas based on a radiation hydrodynamics model

One of fundamental aims of extreme ultraviolet (EUV) lithography is to maximize brightness or conversion efficiency of laser energy to radiation at specific wavelengths from laser produced plasmas (LPPs) of specific elements for matching to available multilayer optical systems. Tin LPPs have been chosen for operation at a wavelength of 13.5 nm. For an investigation of EUV radiation of laser-produced tin plasmas, it is crucial to study the related atomic processes and their evolution so as to reliably predict the optimum plasma and experimental conditions. Here, we present a simplified radiation hydrodynamic model based on the fluid dynamic equations and the radiative transfer equation to rapidly investigate the evolution of radiation properties and dynamics in laser-produced tin plasmas. The self-absorption features of EUV spectra measured at an angle of 45° to the direction of plasma expansion have been successfully simulated and explained, and the evolution of some parameters, such as the plasma temperature, ion distribution and density, expansion size and velocity, have also been evaluated. Our results should be useful for further understanding of current research on extreme ultraviolet and soft X-ray source development for applications such as lithography, metrology and biological imaging.