[en] Short communication

[en] Multiple sclerosis is a neurological rare disease, of which the pathological mechanism has not been fully evaluated. Currently, disease specific imaging method is a open field, which leads to poor correlation between structural imaging and clinical manifestation, disease progress and prognosis. Based on radionuclide tracing technology, PET imaging brings opportunity to disease treatment and therapeutic assessment. This article summarize the new radioactive tracers and imaging methods developed in the field. (authors)

[en] A new Aβ-amyloid imaging agent 7-methoxy-2 (6-fluoropyridin-3-yl) imidazo [2, 1-b]-8-pyridinothiazol (¹⁸F-W372) is synthesized, the non-decay corrected radiochemical yield is (25.3 ± 7.1)% (n = 6), the radiochemical purity is more than 99.5%, and the specific activity is 659-721 PBq/mol. Biodistribution of the ¹⁸F-W372 in mice indicates that uptake is high in brain, the brain is (4.36 ± 1.44)%ID/g at 5 min, the washout from normal brain is fast, and the brain is (0.54 ± 0.16)%ID/g at 30 rain post injection. The acute toxicity test of ¹⁸F-W372 proves its safety in clinical use. The cortical/cerebellar specific uptake is higher in AD patients than in controls at 40 rain after injection of ¹⁸F-W372. ¹⁸F-W372 may have potential as a Aβ-amyloid imaging agent for Alzheimer's disease. (authors)

[en] A new Aβ-Amyloid Imaging agent 7-Methoxy-2 (6-fluoropyridin-3-yl) imidazo [2, 1-b]-8-pyridinothiazol (¹⁸F- W372) was synthesized, the undecay corrected radiochemical yield was 20±n% (n= 3), the radiochemical purity was more than 99.5%, and the specific activity was 19.5 Ci/μmol. Biodistribution of the ¹⁸F-W372 in mice indicates that uptake was high in brain, the brain ID%/g was 4.36±1.44% at 5 min, the washout from normal brain was fast, and the brain ID%/g was 0.54±0.16%/g. At 30 min The acute toxicity test of ¹⁸F-W372 proved it was safely for clinical used. The cortical/cerebellar SUVR was higher in AD patients than controls after injection of ¹⁸F-W372 of 40 min. The result showed that ¹⁸F-W372 is a excellent imaging agent for Aβ-Amyloid. (authors)

[en] The energy spectra and E2 transition probabilities of three-boson nuclei ⁴⁶Ti and ⁵⁴Cr are studied by using the configuration mixing wave function in sdgIBM1 and the boson surface delta interaction. The theoretical result in sdgIBM1 is satisfactory, it can fit much more levels and E2 transition probabilities, and their deviations are even smaller than those in sdIBM1. It is shown that the g boson also plays important role in the vibration region

[en] Objective: To evaluate the value of ¹⁸F-FDG PET/CT in preoperative diagnosis and staging of suspected extrahepatic cholangiocarcinoma (EHCC). Methods: The clinical data of 116 patients (72 males, 44 females; age range 26-89 years) with suspected EHCG from January 2013 to October 2014 were retrospectively analyzed. All patients received preoperative whole body ¹⁸F-FDG PET/CT scan. The imaging results were compared with final clinical diagnosis. The diagnostic sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ¹⁸F-FDG PET/CT were calculated. Two-sample t test was applied to compare lesion SUV_max of malignant and benign diseases. One-way analysis of variance was applied to compare SUV_max of highly, moderately and poorly differentiated tumors. χ² test was used to compare the difference of diagnostic sensitivities for hilar cholangiocarcinomas and common bile duct tumors. Results: All patients were confirmed by exploratory laparotomy and subsequent histologic examination. A total of 94 cases (93 adenocarcinomas and 1 squamous carcinoma) were confirmed malignant and 22 cases (11 biliary calculi, 9 cholangitis, 1 choledochal cyst, 1 tuberculosis) were confirmed benign. The diagnostic sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ¹⁸F-FDG PET/CT for primary tumor were 61.7%(58/94), 77.3%(17/22), 92.1%(58/63), 32.1%(17/53), 64.7%(75/116), respectively. The diagnostic sensitivity and specificity for regional lymph node metastasis were 45.5%(15/33), 91.4%(53/58), and those for distant metastasis were 3/4, 94.3%(82/87). The of malignant tumors were higher than that of benign lesions (4.57 ± 3.75, 2.72 ± 2.48; t = 2.83, P < 0.05), while the differences of SUV_max among highly, moderately and poorly differentiated tumors were not significant (4.89 ± 4.75, 4.23 ± 2.49, 4.47 ± 2.73; F = 0.269, P > 0.05). ¹⁸F-FDG PET/CT showed a lower sensitivity in hilar cholangiocarcinomas than that in common bile duct tumors, while no statistical significance was observed: 48.6%(17/35) vs 69.0%(40/58), χ² = 3.827, P > 0.05. Conclusions: The value of ¹⁸F-FDG PET/CT in preoperative diagnosis and staging of EHCG is limited. It can distinguish some benign diseases from malignant tumors, but with higher false positive for cholangitis. It can help to adjust treatment strategies by detecting distant metastasis. (authors)

[en] Objective: To compare the accuracy of MR-ultrashort echo time (UTE) attenuation correction (AC) methods with that of CT AC methods in brain PET examination. Methods: Ten patients who underwent the brain ¹⁸F-FDG examination of PET/CT and PET/MR were selected randomly. The PET data were attenuation corrected by MRI-UTE and CT methods, and PET_UTE and PET_CT images were obtained. With the threshold segmentation method, the UET and CT attenuation correction maps (μ Maps) were segmented, and their differences in the neurocranium, brain tissue, and air were compared using paired t test. The difference between PET_UTE and PET_CT was analyzed by the statistical parametric map. Results: A significant difference was found between the UTE_μ maps and CT_μ maps in the neurocranium (t = -23.45, P < 0.05) and air (t = 5.29, P < 0.05). The difference rates were -64.8% ± 8.7% and 74.8% ± 44.7%, respectively. No significant difference (-1.5% ± 3.9%) in the brain tissue was found between the two maps (t = -1.24, P > 0.05). The closer the brain was to the skull and the air, the more metabolism was reduced. Conclusions: The UTE sequence can accurately evaluate the μ map of brain tissue, but there was a certain underestimation of PET quantitative analysis in areas close to skull and air area. (authors)

[en] Objective: To investigate the optimal workflow and protocol for integrated PET/MR by comparison with PET/CT. Methods: A total of 228 patients were enrolled in this study for PET/CT and PET/MR evaluation on the same day. Six PET/MR protocols with different MR sequences but the same PET acquisition protocol were investigated and the optimal protocol was identified based on image quality, acquisition time and diagnostic performance. Results: PET/MR workflow was similar to PET/CT, however, some special issues needed to be considered for PET/MR. Among the 6 protocols, protocol No.6 outperformed others for body and head regions. Types of artifacts were found more often in PET/MR than in PET/CT. Conclusions: By optimizing the protocol, PET/MR could achieve almost the same diagnostic performance as PET/CT. However, the issues of long acquisition time and artifacts on PET/MR need to be further improved. (authors)

[en] Objective: To evaluate the effectiveness of a new tracer (7-methoxy-2-(6-¹⁸F-fluoropyridin-3-yl) imidazo [2, 1-β] -8-pyridinothiazole, ¹⁸F-W372 ) in distinguishing patients with AD from healthy controls (HC) by direct comparison with ¹⁸F-W372 and ¹¹C-Pittsburgh compound B (PIB). Methods: Paired ¹¹C-PIB and ¹⁸F-W372 scans were acquired in 8 patients with AD ((64.00±8.81) y, 1 male), 9HC ((64.78±4.02) y, 4 male) and 2 young volunteers. Dynamic PET scans were performed over a period of 40 min after injection of tracers. SUV and cortical-to-cerebellum SUV ratios (SUVR) were calculated. The median age and education across groups were compared using Kruskal-Wallis test. Wilcoxon rank-sum test was used to compare the mini-mental state examination (MMSE) scores between the HC and AD groups. Group differences of SUVR for ¹¹C-PIB and ¹⁸F-W372 were tested using a two-sample t-test. Results: Average MMSE scores were significantly lower in the AD patients than that in the HC (19.13±4.05 vs 28.89±0.78; T=36.00, P<0.01). The AD and HC were similar with respect to age and education (H=28.50 and 35.50, both P>0.05). The AD patients showed increased cortical ¹⁸F-W372 binding (e. g., the posterior and anterior cingulate), while the young volunteers demonstrated minimal cortical accumulation of the tracer. Although cortical-to-cerebellum SUVR of ¹⁸F-W372 in AD patients showed continual increase during the entire 40-min acquisition after injection, the separation between populations was not as robust as that of ¹¹C-PIB. Both tracers showed increased white-matter (WM) binding. The last 5-min phase (i. e. from 35 to 40 min) was taken as a representative sample for further analysis. In this period, the cortical-to-cerebellum SUVR of ¹¹C-PIB was significantly higher in AD patients than that in HC (1.48±0.22 vs 1.06±0.04; t=5.58, P<0.001). Similarly for ¹⁸F-W372, the average SUVR of AD patients was also significantly higher than that of HC (1.31±0.08 vs 1.17±0.06; t=3.78, P<0.01). Conclusions: ¹⁸F-W372 displayed similar affinity and distribution as ¹¹C-PIB. However, its target/nontarget distribution was not satisfactory. As a potential novel amyloid PET imaging agent; further research on ¹⁸F-W372 is warranted. (authors)

[en] The effect of deflected channel on particle motion is equivalent to modulation with a weak-potential having a periodic same as the deflected channel has. The motion equation of a particle has been reduced to the nonlinear differential equation with a weak-periodic modulation by using sine-squared potential. The dechanneling fraction has been derived for a strained superlattice. The main-resonance and sub-resonance have been investigated by using multi-scale method, a global bifurcation and the critical conditions with Smale horse shoe have been analysed by using Melnikov method