ABSTRACT
Objective:To explore the diagnostic value of 68Ga-fibroblast activation protein inhibitor (FAPI) PET for the restaging of patients with colorectal cancer and its impact on treatment strategy. Methods:Patients with colorectal cancer who underwent 68Ga-FAPI PET imaging in the PET Center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from June 2020 to June 2021 were retrospectively analyzed. PET images were evaluated by 3 experienced imaging physicians. Biopsy or postoperative pathology, clinical and imaging follow-up results were as the gold standard. The diagnostic value of PET was compared with conventional imaging (CT/MR), and the impact of 68Ga-FAPI PET on guiding treatment was evaluated. χ2 test and Fisher exact test were used to compare the differences between groups. Results:A total of 33 patients were included (17 males, 16 females, age (52.8±12.3) years), of which 24 were finally diagnosed as recurrence/metastases/progression. The accuracy, sensitivity, specificity, positive predictive value and negative predictive value of 68Ga-FAPI PET in detecting recurrence/metastases/progression of colorectal cancer were 93.9%(31/33), 100%(24/24), 7/9, 92.3%(24/26) and 7/7, respectively. Its accuracy, sensitivity and negative predictive value were significantly higher than those of conventional imaging (64.5%(20/31), 56.5%(13/23) and 7/17; χ2 values: 8.549 and 10.786, all P<0.05). Compared with the clinical or pathological stage before examination, 68Ga-FAPI PET led upstaging to stage Ⅳ in 12 patients (50.0%, 12/24). Of the 31 patients who were correctly diagnosed by 68Ga-FAPI PET, the treatment regimen of 22 patients (71.0%) was changed because of 68Ga-FAPI PET imaging. Conclusion:68Ga-FAPI PET has good diagnostic performance in the restaging of colorectal cancer, which is helpful to further guide clinical treatment strategy.
ABSTRACT
Objective:To explore the feasibility of statistical parametric mapping (SPM) aided semi-quantitative analysis in 11C-Pittsburgh compound B (PIB) β-amyloid (Aβ) PET imaging acquired by hybrid PET/MR, and evaluate its possibility in assisting the diagnosis or differential diagnosis for cognitive impairment. Methods:From January 2018 to September 2019, 13 Alzheimer′s disease (AD) patients (4 males, 9 females; age (59.2±5.8) years) and 10 vascular cognitive disorders (VCD) patients (9 males, 1 female; age (59.5±11.5) years) who underwent 11C-PIB PET/MR in PET center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology were retrospectively analyzed. The standardized uptake value ratio (SUVR) of eight key brain regions (cerebral white matter, striatum, thalamus, posterior cingulate gyrus, frontal cortex, posterior parietal cortex, lateral temporal cortex and occipital cortex) to cerebellum cortex were obtained by manual delineation and SPM-aided semi-automatic segmentation with the help of synchronous three-dimensional T 1 weighted imaging (3D T 1WI). Pearson correlation analysis was carried out on the SUVR obtained by the two methods. Independent-sample t test and paired t test were used to analyze the data. Results:There was no significant difference between AD group and VCD group in age and Mini-Mental State Examination (MMSE) score (19.7±4.7 vs 21.7±3.8; t values: 0.095 and 1.098, both P>0.05). Except thalamus( r=0.179, P=0.413), there were good correlations between SUVR obtained by segmentation and delineation in the other 7 key regions ( r values: 0.678-0.893, all P<0.05). The SUVR of 8 key regions obtained by the two methods in AD group was significantly higher than that in VCD group (1.519-2.055 vs 1.105-1.618; t values: 2.799-11.582, all P<0.01). The SUVR of striatum (1.942±0.205), posterior cingulate gyrus (1.915±0.249), frontal lobe (1.983±0.264), parietal lobe (2.008±0.296) and temporal cortex (1.931±0.254) in AD group was significantly higher than that of cerebral white matter (1.746±0.192; t values: 3.793-6.992, all P<0.01). But in VCD group, there was no region with the SUVR higher than that of cerebral white matter. Conclusions:Hybrid PET/MR can acquire the PET and MRI images synchronously, which can realize the accurate brain segmentation and obtain the semi-quantitative data of key brain regions aided by SPM. The method can analyze the characteristics and differences of amyloid imaging in AD and VCD, which is expected to provide an accurate imaging analysis method for the diagnosis and differential diagnosis of cognitive disorders.
ABSTRACT
Objective To prepare 18F-5-fluoro-N-(2-(diethylamino) ethyl) picolinamide (18F-5-FPN) and evaluate its binding affinity with melanin.Methods 5-bromo-N-(2-(diethylamino) ethyl)picolinamide (precursor) was synthesized and the structure was characterized by ultraviolet (UV),nuclear magnetic resonance (NMR) and mass spectrometry.18F-5-FPN was prepared with FX-XN module through nucleophilic substitution reaction.The product was purified and identified by HPLC.The binding specificity of 18F-5-FPN with melanin was demonstrated by in vitro study of cellular uptake,and in vivo static PET imaging of pigmented B16F10 and amelanotic A375m allografts.Biodistribution study was performed to evaluate the pharmacokinetics of 18F-5-FPN in vivo.Two-sample t test was used for data analysis.Results The structure of precursor was characterized by UV,1H NMR,13C NMR and mass spectrometry.18 F-5-FPN was successfully prepared with radiochemical yield of 5％-8％,radiochemical purity ＞95％ and the specific activity of 100-120 GBq/μmol.The cell uptake study showed that the uptakes of 18F-5-FPN in B16F10 cells at 30,60 and 120 min ((9.80±0.46) ％,(10.34±0.32) ％,(7.27±0.26)％) were significantly higher than those in A375m cells ((1.36±0.14)％,(1.75±0.12)％,(1.54±0.09)％;t =30.3,46.8,38.4,all P＜0.05),and the optimal uptakes were observed at 60 min for both cells.In static PET imaging,the tumors in B16F10-bearing mice were clearly visible with the uptake value of (18.20±3.21) ％ID/g and the T/B ratio of 19.17±10.03 at 1 h postinjection,while no tumor uptake was seen in A375m-bearing mice.The main clearance pathway of 18F-5-FPN was the renal system,which cleared the unbound tracer rapidly.Conclusions 18F-5-FPN can specifically target the melanin in vitro and in vivo with favorable pharmacokinetics and good T/B ratio.18F-5-FPN may be an ideal molecular probe for diagnosis of malignant melanoma.