[en] Objective: To discuss the impact of an iterative reconstruction algorithm (True X) implemented with point spread function (PSF) on image quality and SUV in ¹⁸F-FDG PET, and compare with other reconstruction algorithms. Methods: A total of 79 hypermetabolic lesions from 37 cancer patients (23 males, 14 females, age (63.38 ± 15.25) years) were retrospectively studied. The PET images were reconstructed using the follow-ing six reconstruction algorithms, including FBP, FBP + TOF, iteration, iteration + TOF, True X, True X + TOF. Paired t test was used for statistical analysis. Results: All six reconstruction algorithms showed significant difference in lesion SUV_max. The adoption of PSF increased SUV_max by 15%-16%, and decreased the dispersion of SUV in the liver parenchyma remarkably. Conclusions: Lesion SUV_max calculated from different reconstruction algorithms has significant differences. Caution should be taken in using PSF, as it can improve image quality but may also increase lesion SUV_max. (authors)

[en] Objective: To investigate the potential of ⁹⁹Tc^m-Duramycin and ⁹⁹Tc^m-RGD in detecting vulnerable plaque in rabbit models. Methods: Fifteen healthy New Zealand male rabbits were randomly divided into group A (control group, n = 5), group B (stable plaque group, n = 5) and group C (vulnerable plaque group, n = 5). Animals were injected with ⁹⁹Tc^m-Duramycin and ⁹⁹Tc^m-RGD at the end of 4, 8 and 12 weeks. SPECT/CT scanning was performed at 0.5 h post injection. One rabbit was sacrificed at the end of 4 weeks and one at the end of 8 weeks after imaging. The others were sacrificed at the end of 12 weeks after imaging studies. All aortas were collected. Intravascular ultrasound (IVUS) was performed at the end of B, 12 weeks before SPECT/CT scanning. The data was analyzed with paired t test. Results: In group A, the aortas had little uptake of the two probes. In group B, the aortas showed obvious radioactive uptake of ⁹⁹Tc^m-Duramycin and ⁹⁹Tc^m-RGD at the end of 8 weeks and 12 weeks, while ⁹⁹Tc^m-Duramycin gave better display than ⁹⁹Tc^m-RGD. In group C, ⁹⁹Tc^m-Duramycin uptake was higher than ⁹⁹Tc^m-RGD uptake in the aorta. The T/NT ratios of ⁹⁹Tc^m-Duramycin and ⁹⁹Tc^m-RGD in group C were 2.14 ± 0.34 and 1.46 ± 0.34 (t = 4.072, P < 0.05) at the end of 4 weeks, 2.93 ± 0.41 and 1.66 ± 0.22 (t = 5.578, at the end of 8 weeks, 3.25 ± 0.29 and 1.81 ± 0.28 (t = 19.692, P < 0.05) at the end of 12 weeks. In isolated specimen of group C, the yellow lipid plaque of the intima bulged on the lumen at the end of 12 weeks. IVUS indicated that, at the end of 8 weeks and 12 weeks, the endometrial thickness of group C was (450 ± 104) mm and (767 ± 52) mm (t = 44.024, P < 0.05) respectively, and the rates of luminal stenosis were (29.30 ± 2.81)% and (37.98 ± 6.41)% (t = 9.226, P < 0.05). Conclusions: Both ⁹⁹Tc^m-Duramycin and ⁹⁹Tc^m-RGD may be used to detect vulnerable plaque at early time. ⁹⁹Tc^m-Duramycin may detect vulnerable atherosclerotic plaque earlier than ⁹⁹Tc^m-RGD and provide better diagnostic image. (authors)

[en] Objective: To evaluate ¹⁸F-fluorodeoxyglucose (FDG) PET/CT in the rabbit model of vulnerable plaques by correlation with ⁹⁹Tc^m-Arg-Gly-Asp (RGD) SPECT/CT imaging, lipid levels, pathological and immunoh1stochemical results. Methods: Sixteen male New Zealand white rabbits were randomly divided into normal diet group (group A, n = 4), stable plaque group (group B, n = 4) and vulnerable plaque group (group C, n = 8) using completely random grouping method. The animals were given abdominal aorta sham operation (groups A and B) or balloon injury of the abdominal aorta (group C) 2 weeks after feeding. Animals were injected with ¹⁸F-FDG and ⁹⁹Tc^m-RGD respectively at the end of 4, 8 and 12 weeks. PET/CT was performed at 1, 2 and 3 h post-injection. SPECT/CT was performed at 30 min post-injection. One rabbit was sacrificed at the end of 4 and 8 weeks after imaging studies, respectively. The others were sacrificed at the end of 12 weeks after imaging studies. All abdominal aortas were harvested. Pathology and immunocytochemistry analysis were performed. The data were analyzed by one-way analysis of variance and Pearson correlation analysis. Results: There was no uptake in any group at 4th week and no uptake in group A or group B at 8th week. There was mild uptake in group B at 12th week and group C at 8th week. There was intense uptake in group C at 12th week, whereas both mean standardized uptake value (SUV_mean) and maximum standardized uptake value (SUV_max) were significantly higher than the other two groups (F values: 7.952, 14.279, both P < 0.05). In group C, SUV_max (0.43 ± 0.08, 0.68 ± 0.06, 1.74 ± 0.63) and SUV (0.37 ± 0.03, 0.56 ± 0.03, 1.26 + 0.23) had significant difference at 3 h post-injection for imaging at 4th, 8th and 12th week (F values: 10.939, 39.747, both P < 0.05). At 12th week, there was a strong correlation between the uptake of ¹⁸F-FDG and target/non-target (T/NT) ratio of ⁹⁹Tc^m-RGD in all groups(r values: 0.748, 0.709, both P < 0.05). Histopathology results showed that the plaques had rich macrophages and a small amount of smooth muscle cells in group C, little macrophages in group B, while no macrophages in group A. Conclusion: ¹⁸F-FDG PET/CT might be an effective noninvasive method for early assessment of aortic vulnerability to atherosclerotic plaque. (authors)

[en] Objective: To investigate the value of ⁹⁹Tc^m-Duramycin SPCET/CT in the detection of vulnerable plaque (VP) in atherosclerotic (AS) rabbit models. Methods: Sixteen New Zealand male rabbits were randomly divided into three groups: group A (sham-operated group, n = 4), group B (stable plaque group, n = 4) and group C (VP group, n = 8). Group A was fed on normal diet, and the other 2 groups were fed on cholesterol diet for 12 weeks. Femoral artery dissection sham-operation was done in group A and group B, while balloon-induced abdominal aorta wall injury was produced in group C after 2 weeks' feeding. Animals were injected with ⁹⁹Tc^m-Duramycin (74 MBq/kg) and then SPECT/CT imaging was performed at the end of 4, 8, and 12 weeks, respectively. Abdominal aortas were explanted for ex vivo imaging and histological characterization of plaque. The apoptosis index (AI) was calculated. One-way analysis of variance was used to analyze data. Results: There was no radioactive uptake by the abdominal aorta in each group at the end of 4 weeks and no uptake in group A and group B at the end of 8 weeks. There was slightly uptake radioactive uptake by the abdominal aorta in group B at the end of 12 weeks and in group G at the end of 8 weeks. There was intense uptake at the lesions of AS rabbits in group C at the end of 12 weeks, and the T/NT value significantly higher than that of the other two groups (3.40 ± 0.22 vs 2.12 ± 0.65, 2.68 ± 0.18, F = 198.775, P < 0.05). The result was confirmed in the ex vivo imaging of the explanted aorta. The AI of group C was significantly higher than that of group A and B ((25.4 ± 6.32)% vs (0 ± 0.02)%, (5.3 ± 1.97)%, F = 70.260, P < 0.05). Conclusions: ⁹⁹Tc^m-Duramycin scintigraphy could identify the apoptosis of VP in the rabbit AS models. It is a promising non-invasive method to diagnose AS plaques. (authors)

[en] A "1"8F-labelling prosthetic group named as N-[2-(4-"1"8F-fluorobenzamido) ethyl] maleimide ("1"8F-FBEM) was prepared for peptides and protein labeling, and the radiophar-maceuticals prepared from this prosthetic group were designed for positron emission tomography (PET) imaging. This prosthetic group was synthesized by the react ion of N-succinimidyl 4-"1"8F-fluorobenzoate ("1"8F-SFB) with N-(2-aminoethyl) maleimide trifluoroacetate salt. The total synthesis time from "1"8F-to "1"8F-FBEM w as about 2.5 h with decay corrected radiolabeling yield of 9.8%. The double bond contained in maleimide of the synthon can react with sulfhydryl groups with high efficiency under room temperature, thus it can be applied in indirect radiofluorinations of thiol-containing molecules such as peptides and protein. "1"8F-labeled galactosyl-neoglycoalbum in ("1"8F-FBEM-NGA) was developed based on "1"8F-FBEM for example. (authors)

[en] Objective: To investigate the feasibility of a novel molecular probe ⁹⁹Tc^m-3P4-RGD₂ in evaluating arterial plaque stability alter atorvastatin intervention in rabbits with SPECT/CT. Methods: Eighteen male New Zealand rabbits were randomly divided into group A (stable plaque), group B (vulnerable plaque), and group C (vulnerable plaque with statin intervention). All rabbits wee fed with high-fat food for 12 weeks. After high-fat feeding for two weeks, sham surgery was performed on group A. In the meantime, abdominal aorta injury was performed on group B and group C. After that, rabbits of group C were given oral atorvastatin (2.5 mg·kg^-1·d^-1). ⁹⁹Tc^m-3P4-RGD₂ SPECT/CT imaging was performed on each group at the end of 4, 8 and 12 weeks. T/NT ratios were calculated. Animals were sacrificed at the end of 12 week after imaging studies. The abdominal aortas were collected, imaged with SPECT/CT, and evaluated by pathological HE staining and immunohistochemical analysis. MVD was calculated. Differences among 3 groups were analyzed using one-way analysis of variance. Results: There was no significant radioactive uptake in the abdominal aortas of three groups on the 4th week's imaging. The radioactive uptake in abdominal aortas increased slightly on the 8th week, with the highest radioactive uptake in group B. The radioactivity in abdominal aortas of the 3 groups maintained increasing on the 12th week, with T/NT ratios of 1.579 ± 0.217, 1.873 ± 0.226 and 1.524 ± 0.237, respectively (F = 8.984, P < 0.05). In ex vivo abdominal aorta images, especially images of group B, radioactivity in lesion sites was higher than that in normal tissue. Accordingly, results of HE staining showed that artery plaques of group A and group C were grade II and group B was grade IV. The MVD of group A, B and C was 8.17 ± 1.17, 15.86 ± 1.07 and 7.17 ± 1.60, respectively (F = 90.36, P < 0.05). Conclusion: ⁹⁹Tc^m-3P4-RGD₂ SPECT/CT imaging has a high sensitivity in the evaluation of arterial plaque stability after statin intervention in rabbits. (authors)

[en] This study reports the synthesis and characterization of fenazaquin analogue [¹⁸F]FP2OP as a potential myocardial perfusion imaging (MPI) agent. The total reaction time for [¹⁸F]FP2OP, including final high-performance liquid chromatography purification, was about 1.5 h. Typical decay-corrected radiochemical yield was 55%. The radiochemical purity was >98%. Biodistribution in mice showed that the heart uptake was (41.90±4.52)%ID/g, (24.80±0.71)%ID/g at 2, 60 min post-injection time, respectively. The ratios of heart/liver, heart/lung and heart/blood were 6.83, 9.49 and 35.74, respectively at 2 min after injection. [¹⁸F]FP2OP was metabolized to produce lipophilic molecule in blood and urine at 30 min. The promising biological properties of [¹⁸F]FP2OP afford potential applications as a MPI agent in the future. (authors)

[en] A novel bifunctional coupling agents-biomolecular compound DMP-NGA was prepared by coupling the SATP with galactosyl-neoglycoalbumin (NGA). The DMP-NGA was labeled with technetium-99 m, and the radiochemical purity in excess of 98% after purified with HPLC. In vivo biodistribution showed that ^99mTc-DMP-NGA had very high initial liver uptake with good retention. The liver accumulated 99.35±9.77%, 74.25±3.03%, 52.47±7.58% of the injected dose per gram at 5, 30 and 120 min after injection, respectively. It had relative higher initial liver uptake and much lower blood uptake than that of ^99mTc-GSA. The liver/blood ratio reached 83.4 at 30 min post-injection, while the ratio of liver/kidney was 14.4. The uptakes in other organs in the abdomen were also slightly low. In addition, the hepatic uptake of ^99mTc-DMP-NGA was blocked by preinjecting free GSA as blocking agent. The result indicates that ^99mTc-DMP-NGA has specific binding to ASGP receptor. Images acquired with Kodak In-Vivo Imaging System FX Pro showed significant difference before and after inhibition. The promising biological properties of ^99mTc-DMP-NGA afford potential applications in liver receptor imaging for assessment of hepatocyte function.

[en] This study reports the synthesis and characterization of N-(3-(4-(2-methoxyphenyl)piperazin-1-yl)propyl-4-[¹⁸F]fluorobenzamide ([¹⁸F]MPP3F). The total reaction time for [¹⁸F]MPP3F, including final high-performance liquid chromatography purification, was about 3 h. Typical decay-corrected radiochemical yield was 18.4±3.1%. The radiochemical purity was >98%. Biodistribution in mice showed that [¹⁸F]MPP3F is a potential brain imaging agent for positron emission tomography. The brain uptake of [¹⁸F]MPP3F was 6.59±0.77% Injected Dose/g at 2 min post-injection time. A brain-to-blood ratio of 3.67 was reached at 15 min after injection.

[en] Objective: To study the factors affecting the synthesis of ¹⁸F-MyoZone, and to evaluate its potential as a myocardial perfusion imaging (MPI) agent in normal Chinese mini-swine. Methods: ¹⁸F-MyoZone was prepared by substituting the leaving group toluenesulfonyloxy (OTs) from the precursor compound with ¹⁸F-fluoride (¹⁸F-F^-). The conditions affecting the labeling yield were studied by varying the amount of K₂C0₃ and precursor compound, ¹⁸F-fluorination reaction time and temperature. PET was performed at 5, 30, 60 and 120 min post-injection on normal Chinese mini-swine. Results: The doses of K₂C0₃ and precursor, the reaction time and the reaction temperature could affect the labeling yield of ¹⁸F-MyoZone, especially K₂C0₃. The optimized synthetic condition was 1.0 mg K₂C0₃, 2.0 mg mpp2-OTs, 20 min reaction time at 90 ℃. The total radio-synthesis time in this condition was 60 min. The uncorrected radiochemical yield was (24.0 ± 5.1)%. The radiochemical purity was > 98%, PET imaging showed that ¹⁸F-MyoZone had high initial uptake (SUV = 8.17 ± 1.83 at 5 min post-injection) and good retention (SUV = 5.78 ± 0.99 at 120 min post-injection) in the heart. The clearance of ¹⁸F-MyoZone from liver was very fast. The heart/liver ratios were 332, 5.31, 6.09 and 5.76 at 5, 30, 60 and 120 min post-injection, respectively. From 5 to 120 min post-injection, the outline of heart was clear and intact. There was almost no interference from the adjacent organs. The quality of PET images was highly satisfactory. Conclusions: ¹⁸F-MyoZone has the potential to be a good myocardial perfusion agent. The amount of K₂C0₃ used could significantly affect the labeling yield of ¹⁸F-MyoZone. (authors)