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Objective:To investigate the radiation dosimetry and biodistribution of 68Ga-FAPI-04 PET/CT in patients with hepatobiliary tumor. Methods:A total of six patients with hepatic lesions who underwent PET/CT examination in Peking Union Medical College Hospital were enrolled. After intravenous injection of radiotracer 68Ga-FAPI-04 at (170.57 ± 14.43) MBq, whole-body imaging were performed at the time points of 3, 10, 15, 20, 30 and 60 min, respectively. Biodistribution pattern was observed. Regions of interest were manually delineated. Radiation dosimetry of all target organs were calculated by Olinda/EXM software. Results:The radioactive uptake dissipated gradually in liver whereas it was relatively stable in tumor lesions. The average SUV max of tumor lesions reached the maximum value (13.87± 2.55) at 20 min after injection. The target-to-background ratio increased with time, reaching the maximum value (10.09 ± 8.17) at 30 min after injection. The average effective dose in total body was (0.020 ± 0.002) mSv/MBq and organ with the highest effective dose was bladder wall at (0.146 ± 0.035) mSv/MBq. Conclusions:The effective dose in total body of 68Ga-FAPI-04 was similar to that of 18F-FDG. 68Ga-FAPI-04 is expected to be a PET/CT radiotracer for hepatobiliary tumors in consideration of rapid tumor uptake, low accumulation of liver background, and no influence of blood sugar levels.
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Objective:To prepare 68Ga-fibroblast activation protein inhibitor (FAPI)-04, and evaluate its biodistribution and imaging characteristics in animals and healthy volunteers, in order to investigate the clinical translation potential. Methods:68Ga-FAPI-04 was synthesized by a manual method and its radiolabeling yield, radiochemical purity, and stability ( in vivo and in vitro) were analyzed. ICR mice ( n=16) were scarified at 5, 30, 60 and 120 min postinjection of 68Ga-FAPI-04 (1.11 MBq) to measure radioactive counts in main organs. The dynamic mircoPET imaging was acquired for 60 min on 3 ICR mice, and tumor imaging capabilities were examined with nude mice bearing HepG2 tumors. Furthermore, 2 healthy volunteers (1 male with age of 64 years, 1 female with age of 56 years) were recruited for the investigation of probe biodistribution in humans. A serial whole-body dynamic PET/CT scan was performed immediately following injection. Results:68Ga-FAPI-04 was synthesized within 20 min with the radiochemical yield of (68.7±4.0)% (decay corrected). The radiochemical purities of 68Ga-FAPI-04 were over 99% and the products were stable for 180 min in vitro and for 90 min in blood. 68Ga-FAPI-04 was mainly cleared through urinary tracts, while other organs only showed mild tracer accumulation. MicroPET imaging showed high uptake of 68Ga-FAPI-04 in the tumor tissue of mice, and the ratio of tumor/liver was 2.14±0.01 (35 min). The PET/CT imaging results of healthy volunteers revealed 68Ga-FAPI-04 could be quickly cleared. Conclusion:68Ga-FAPI-04 has many advantages for PET imaging, such as easy labeling, good stability, quick clearance and low background signals in the liver, which can be used as an attractive PET tracer for detection hepatocellular carcinoma.
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Objective To assess the diagnostic value of 99Tcm-ECD SPECT for hyperacute cerebral ischemia using rats models.Methods A stable and permanent acute cerebral ischemia model using unilateral middle cerebral occlusion was tested in 24 healthy SD rats.The rats were randomly divided into 6 groups according to the time duration between imaging and induced-ischemia (1,2,3,4,5 and 6 h,respectively).The rats were sacrificed immediately after 99Tcm-ECD SPECT/CT imaging and then the brain tissue was dissected for triphenyl tetrazolium chloride (TTC) and HE staining.The count ratio of affected cortex to the contralateral cortex of ＜ 50％ was defined as ischemia on micro SPECT/CT.The volume of the ischemic area was calculated on both SPECT/CT and TTC images.Paired t test was used to determine the statistical difference between the volumes on SPECT/CT and TTC staining.Results The ischemia volume evaluated by TTC staining at 1,2,3,4,5 and 6 h after occlusion was (73.98 ± 27.76),(90.75 ±29.00),(135.00±40.83),(136.25±22.51),(158.50±32.72) and (168.00±32.75) mm3,respectively.The corresponding ischemia volume evaluated by micro SPECT/CT was (98.50 ± 27.77),(110.40±26.80),(157.00±36.82),(165.50±26.54),(175.75±31.16) and (177.25 ±34.33) mm3,respectively,which was concordant with that by TTC staining at each time point (t:-1.681 to-0.390,all P ＞0.05).The ischemic area on micro SPECT/CT imaging was consistent with the pink area by TTC staining.The volume evaluated by micro SPECT/CT tended to be constant 3 h after the occlusion.The ischemia volume showed no significant difference among 3,4,5 and 6 h (all P ＞ 0.05).Conclusions Micro SPECT/CT may have an haemodynamic value for evaluating in vivo cerebral ischemia applied in a rat model.It might have clinical value for the evaluation and decision-making of ultra acute cerebral infarctions.