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Objective:To study the impact of different scattering correction algorithms in the reconstruction of PET/CT images on image artifacts and the precision of quantitative parameters.Methods:The phantom as described in the National Electrical Manufacturers Association (NEMA) NU2 standard was filled with 18F. The background activity was fixed, and the activity of the solution in the spheres was adjusted to obtain several configurations, including the normal ratio group (4.08∶1) and the extreme ratio group (200∶1). The surface contamination group with the same ratio as the extreme ratio group contained a small radioactive source with different doses of 18F (74, 37, 3.7 and 0.37 MBq) placed at the surface of the phantom. PET/CT images of 30 patients (21 males, 9 females, age: (44.5±10.2) years) from Peking University Cancer Hospital & Institute between July 2012 and December 2021 were retrospectively analyzed, including 10 with normal images ( 18F-FDG) and 20 with abnormal images (10 with dislocation during acquisition, 10 with surface contamination). The images were reconstructed with relative and absolute scattering correction. The phantom was evaluated using the target to background ratio (TBR) and the artifact classification. CV as well as the artifact classification were used to compare the clinical image quality. Mann-Whitney U test and χ2 test were used to analyze data. Results:In the normal ratio group and the extreme ratio group, the TBRs of phantom images reconstructed with relative correction were significantly higher than those with absolute correction (normal ratio group: 3.30(1.94, 4.53) vs 2.72(1.56, 3.56); z=-2.20, P=0.028; extreme ratio group: 105.47(45.62, 162.82) vs 101.36(43.96, 155.57); z=-1.99, P=0.046). In the surface contamination group, with the increase of the activity of the small source, the artifact became more obvious, and the artifact classification score of absolute correction was significantly better than that of relative correction (1.5(1.0, 2.0) vs 2.5(2.0, 3.0); z=-2.00, P=0.046). In the 10 normal 18F-FDG PET/CT patients, the CVliver of the relative correction (9.67%(8.00%, 11.00%)) was significantly lower than that of absolute correction (11.00%(9.00%, 12.00%); z=-2.57, P=0.010), indicating the higher image quality of images with relative correction. In abnormal images, the image quality of absolute correction was significantly higher than that of relative correction with fewer and less severe artifacts (dislocation cases: 9/10 vs 4/10; χ2=5.50, P=0.019; surface contamination cases: 9/10 vs 4/10; χ2=5.50, P=0.019). Conclusions:The relative scattering correction is suitable for normal situations in clinical PET acquisition. However, with dislocation or surface contamination, the absolute scattering correction helps to reduce the artifacts and improve the image quality.
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Objective:To compare the value of 68Ga-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid- D-Phe1-Tyr3-Thr8-octreotide (DOTATATE) and 18F-fluorodeoxyglucose (FDG) PET/CT imaging in the detection of bone metastasis in neuroendocrine neoplasm (NEN). Methods:From January 2014 to July 2019, 29 NEN patients (19 males, 10 females, age: 35-76 years) with bone metastasis who underwent 68Ga-DOTATATE and 18F-FDG PET/CT imaging within one month in Peking University Cancer Hospital & Institute were retrospectively enrolled. Patients were divided into Ki-67≤20% and Ki-67>20% groups according to the tumor proliferation activity, and osteolysis, osteogenesis and no change groups according to the CT findings of bone metastases. The differences of the number and radioactive uptake (maximum standardized uptake value (SUV max) ratio of bone lesion to normal bone (SUV T/B)) of detected bone metastases between 68Ga-DOTATATE and 18F-FDG PET/CT imaging were analyzed. χ2 and Mann-Whitney U tests were used to analyze the data. Results:The sensitivity of 68Ga-DOTATATE and 18F-FDG PET/CT imaging were 75.9%(22/29) and 82.8% (24/29) respectively, and there was no significant difference between the two modalities ( χ2=0.42, P>0.05). The numbers of cases with bone lesions detected by 68Ga-DOTATATE PET/CT imaging in pelvis, spine, ribs, proximal limbs, sternoclavicular scapula and skull were all higher than those of 18F-FDG PET/CT imaging (23, 22, 20, 14, 14, 10 vs 12, 19, 13, 11, 10, 6, respectively). The 68Ga-DOTATATE PET/CT imaging was significantly superior to 18F-FDG imaging in detecting bone metastases (9(3, 36) and 3(0, 18)) and SUV T/B(11.10(3.35, 22.30) and 1.60(1.05, 2.70); U values: 281.000, 77.000, both P<0.001). 68Ga-DOTATATE PET/CT imaging found more bone lesions in well differentiated NEN (Ki-67≤20%) group (11(2, 38) and 2(0, 13)) and osteogenic bone metastasis group (31(3, 100) and 3(0, 31); U values: 105.500, 69.500, both P<0.05). SUV T/B of 68Ga-DOTATATE PET/CT imaging was significantly higher than 18F-FDG PET/CT imaging in all subgroups ( U values: 3.000-22.000, all P<0.05). Conclusion:The 68Ga-DOTATATE PET/CT imaging is superior to 18F-FDG PET/CT imaging in the detection of bone metastasis in NEN.
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Objective:To estimate the renal absorbed dose in the treatment of neuroendocrine tumors using 177Lu-DOTA-TATE and to assess the radiation safety and guide the treatment. Methods:The dosimetric calculations of patients treated with 177Lu-DOTA-TATE were carried out based on planar images of single photon emission computed tomography (SPECT). The regions of interest (ROIs) of the whole body and kidneys were delineated and converted into activity. Accordingly, the time-activity curves of the ROIs were obtained. The effective half-lives and cumulative activity of ROIs were calculated through the fitting of a single exponential equation of the ROIs. Then the absorbed doses were calculated based on the medical internal radiation dosimetry (MIRD) formalism. Results:A total of 11 patients with neuroendocrine tumors received 18 cycles of treatments with 177Lu-DOTA-TATE. The effective half-lives of 177Lu-DOTA-TATE in the whole body and kidneys were 20.0-99.8 h and 38.2-75.2 h, respectively, with an average of (57.3 ± 21.4) h and (53.1 ± 12.5) h, respectively. The renal absorbed doses of 177Lu-DTA-TATE were 0.25-1.48 mGy/MBq, with an average of (0.90 ± 0.31) mGy/MBq. The minimum and maximum renal absorbed doses in a single treatment cycle were 1.8 Gy and 9.6 Gy, respectively, while the maximum renal absorbed dose in multiple treatment cycles was 21.7 Gy. Conclusions:The renal absorbed doses in the treatment of neuroendocrine tumors using 177Lu-DOTA-TATE were estimated. The result indicate that the renal absorbed doses were lower than the tolerable dose limits. This study is expected to guide the precise treatment of neuroendocrine tumors.
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Chemotherapy-related cardiotoxicity is common and has become one of the factors that affect the prognosis of patients. Early identification and intervention of chemotherapy-related cardiotoxicity is very important. Currently, the commonly used clinical, imaging and laboratory examination methods have their own shortcomings, while PET/CT imaging has not been widely used for chemotherapy-related cardiotoxicity. This article reviews the current application and deficiencies of PET/CT imaging in animal experiments and human trials of chemotherapy-related cardiotoxicity.
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Objective To prepare a novel somatostatin receptor (SSTR) antagonist 68Ga-1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA)-JR11 (Cpa-c(D-Cys-Aph(Hor)-D-Aph(Cbm)-Lys-Thr-Cys)-D-Tyr-NH2 ) tracer and observe its biodistribution and microPET imaging in mice. Methods One ml HCl (0.05 mol/L) containing 68GaCl3(148 MBq) was added into 65μl NaAc (1 mol/L) and 4μg NOTA-JR11. The mixture reacted at 95 ℃ for 15 min, and then was purified with Sep-Pak? C18 Light column to obtain 68 Ga-NOTA-JR11. 68 Ga-NOTA-JR11 was subjected to quality control analysis including radiochemical purity and in vitro stability by radio-high performance liquid chromatography. Biodistribution of 68Ga-NOTA-JR11 (0.37 MBq) in BALB/c mice (n=9) at 5, 30, 60 min postinjection were observed (n=3 for each time point), and the percentage activity of injection dose per gram of tissue (％ID/g) was calculated. 68Ga-NOTA-JR11 (14.8 MBq) microPET imaging of BALB/c mice (n=1) at 60 min postinjection was observed. Results 68 Ga-NOTA-JR11 was obtained successfully within 15 min, with yielding rate of 90％, radiochemical purity of more than 99％, and specific activity of 6. 10 GBq/μmol. The tracer showed excellent stability ( radio-chemical purity:95％) in different buffers within 150 min. The biodistribution was basically consistent with microPET imaging results. 68 Ga-NOTA-JR11 was metabolized through the kidneys and had low uptake in the liver ((0.75±0.26) ％ID/g) at 60 min postinjection. Conclusions 68 Ga-NOTA-JR11 can be prepared rapidly, with high yielding rate and radiochemical purity. Biodistribution and imaging results provide basic information for the further study of somatostatin receptor imaging in neuroendocrine tumors.
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Objective To evaluate the value of 18F-FDG PET/CT in tumor staging in patients with pancreatic cancer.Methods A total 77 patients (from June 2010 to August 2015;44 males, 33 females, age range 36-83 years) who underwent 18F-FDG PET/CT examination for pancreatic cancer and confirmed with pathology were enrolled in this retrospective study.All patients had not been treated before the PET/CT scanning and received surgery or biopsy 4 weeks after the scanning.Two-sample t test and ROC curve analysis were used for data analysis.Results 18F-FDG uptake was higher in 94.8%(73/77) of pancreatic lesions than that in normal pancreatic tissue.The range of SUVmax of pancreatic lesions was 2.4-13.4(mean: 6.2±2.4).SUVmax of patients with smaller primary lesion (minor axis≤2.0 cm) was significantly lower than that of larger lesion group (minor axis >2.0 cm;t=-2.661, P<0.05).A total of 46 patients underwent lymph node excision, and the mean number of excised lymph nodes per patient was 13.8±9.2.About 56.5%(26/46)cases with lymph nodes metastases were confirmed with pathology.When the cut-off value of minor axis of regional lymph nodes was 0.45 cm, ROC curve showed that the sensitivity, specificity and AUC were 84.8%(39/46), 65.2%(30/46) and 0.788, respectively.When the cut-off value of SUVmax of regional lymph nodes was 2.05, the sensitivity, specificity and AUC were 54.3%(25/46), 80.4%(37/46) and 0.759, respectively.18F-FDG PET/CT changed 18.2%(14/77)of patients′ treatment plan.Conclusions 18F-FDG PET/CT is a useful tool in pancreatic cancer staging.Though 18F-FDG PET/CT has no significant advantages in N-staging, it really helps to make a more accurate M-staging for clinical decision.