68Ga-DOTATATE/18F-FDG two-day low-dose total-body PET/CT imaging is increasingly employed to facilitate the diagnosis,prognosis,and heterogeneity assessment of neuroendocrine neoplasms.We present a consensus on operational guideline for a two-day combined imaging from experts in low-dose/ultra-low-dose total-body PET/CT from several domestic medical institutions.

Objective:To explore the relationship between 18F-fibroblast activation protein inhibitor (FAPI)-42 SUV max of primary gastric cancer and clinicopathological factors of patients. Methods:Fifty-one patients (31males, 20 females, age: 51(47, 65) years) with gastric cancer who underwent 18F-FAPI-42 PET/CT before surgical resection in Nanfang Hospital, Southern Medical University from February 2022 to January 2023 were analyzed retrospectively. The clinicopathological factors that might affect tumor SUV max (including gender, age, tumor location, pathological type, histological grade, Lauren classification, vascular and(or) neural invasion, programmed cell death-ligand 1 (PD-L1) expression, pathologic(p)T stage, pN stage and pTNM stage) were evaluated by the univariate analysis (Mann-Whitney U test or Kruskal-Wallis rank sum test) and multivariate analysis (multiple linear regression analysis). Results:The sensitivity of 18F-FAPI-42 PET/CT in the diagnosis of patients with primary gastric cancer was 82.35% (42/51). The diagnostic sensitivities for early gastric cancer (T1) and locally advanced gastric cancer (T2-T4) were 59.09%(13/22) and 100%(29/29), respectively. The SUV max of primary lesion was 4.90(1.71, 12.51). The univariate analysis showed that SUV max of primary gastric cancer was related to tumor location ( z=-2.00, P=0.046), pT stage ( H=36.94, P<0.001), pN stage ( z=-3.89, P<0.001), pTNM stage ( H=31.49, P<0.001) and vascular and(or) nerve invasion ( z=-5.22, P<0.001), but not related to pathological type, histological grade, Lauren typing, and PD-L1 expression ( z values: from -1.78 to -0.09, all P>0.05). pT stage was found to be a significant independent factor for SUV max in primary gastric lesion by multivariate analysis ( t=2.52, P=0.015). Conclusions:The 18F-FAPI-42 SUV max of primary tumor was related to tumor location, pT stage, pN stage, pTNM stage, and vascular and(or) nerve invasion; pT stage is an independent factor affecting tumor SUV max. The ability of 18F-FAPI-42 PET/CT to detect gastric cancer is mainly affected by pT stage.

In recent years, fibroblast activation protein (FAP) has emerged as an attractive target for the diagnosis and radiotherapy of cancers using FAP-specific radioligands. Herein, we aimed to design a novel ¹⁸F-labeled FAP tracer ([¹⁸F]AlF-P-FAPI) for FAP imaging and evaluated its potential for clinical application. The [¹⁸F]AlF-P-FAPI novel tracer was prepared in an automated manner within 42 min with a non-decay corrected radiochemical yield of 32 ± 6% (n = 8). Among A549-FAP cells, [¹⁸F]AlF-P-FAPI demonstrated specific uptake, rapid internalization, and low cellular efflux. Compared to the patent tracer [¹⁸F]FAPI-42, [¹⁸F]AlF-P-FAPI exhibited lower levels of cellular efflux in the A549-FAP cells and higher stability in vivo. Micro-PET imaging in the A549-FAP tumor model indicated higher specific tumor uptake of [¹⁸F]AlF-P-FAPI (7.0 ± 1.0% ID/g) compared to patent tracers [¹⁸F]FAPI-42 (3.2 ± 0.6% ID/g) and [⁶⁸Ga]Ga-FAPI-04 (2.7 ± 0.5% ID/g). Furthermore, in an initial diagnostic application in a patient with nasopharyngeal cancer, [¹⁸F]AlF-P-FAPI and [¹⁸F]FDG PET/CT showed comparable results for both primary tumors and lymph node metastases. These results suggest that [¹⁸F]AlF-P-FAPI can be conveniently prepared, with promising characteristics in the preclinical evaluation. The feasibility of FAP imaging was demonstrated using PET studies.

Objective:To explore and compare the value of radiomic features based on 18F-fluorodeoxyglucose (FDG) PET and CT in distinguishing epidermal growth factor receptor (EGFR) mutation status in patients with lung adenocarcinoma. Methods:Pretreatment 18F-FDG PET/CT images and EGFR gene status of 114 patients (64 males and 50 females, aged range: 35-84 (average age: 61) years) with primary lung adenocarcinoma between January 2017 and December 2017 were retrospectively collected. The volume of interest was drawn manually slice by slice, then the features were extracted by the LIFEx software. The parameters were screened by least absolute shrinkage and selection operator (LASSO) method for 200 times, and ten-fold cross-validation was used to select the best tuning parameter λ. Three models, namely M PET, M CT, M PET+ CT, were constructed by binary logistic stepwise regression. The receiver operating characteristic (ROC) curve was generated and the corresponding area under the curve (AUC), sensitivity, specificity and accuracy were calculated. The AUCs of three models were compared by Delong test. Results:Totally, 53.51%(61/114) patients were with wild type EGFR and 46.49%(53/114) patients had EGFR mutation. There were 3, 3, 7 parameters selected to form M PET, M CT, M PET+ CT, respectively. The AUCs for M PET, M CT, M PET+ CT were 0.730, 0.752 and 0.866 respectively. When the cut-off values were 0.427, 0.522, 0.378 for M PET, M CT and M PET+ CT, the Youden index were up to the maximum as 0.420, 0.405, 0.630, with sensitivities of 83.0%(44/53), 58.5%(31/53), 92.5%(49/53), specificities of 59.0%(36/61), 82.0%(50/61), 70.5%(43/61) and accuracies of 70.2%(80/114), 71.1%(81/114), 80.7%(92/114), respectively. There was no significant difference between AUC of M PET and M CT ( z=-0.320, P>0.05). The differences of AUCs between M PET+ CT and M PET, M PET+ CT and M CT were statistically significant ( z values: 2.963, 2.523, both P<0.05). Conclusions:PET, CT and PET+ CT radiomic features are all associated with EGFR gene expression in lung adenocarcinoma. M PET+ CT has the highest predictive efficiency.

Objective To explore the differences in the prognosis of patients with different immunophenotypes gastrointestinal diffuse large B-cell lymphoma (GI-DLBCL) who received different treatment strategies.Methods From March 2006 to January 2016,at Nanfang Hospital,Southern Medical University in Guangzhou,the clinical data of 99 patients with pathologically confirmed GI-DLBCL were retrospectively analyzed.According to treatment strategies,patients were divided into chemotherapy alone group and combination of surgery and chemotherapy group.According to immunophenotypes,patients were divided into germinal center B-cell-like (GCB) type and non-GCB type.The two-year progression-free survival (PFS) rate and overall survival (OS) rate were evaluated.Kaplan-Meier analysis,log-rank test and Cox regression were performed for statistical analysis.Results Among the 99 patients with GI-DLBCL,51 patients were treated with chemotherapy alone,and 48 patients were treated with combination of surgery and chemotherapy.Forty-one cases were GCB phenotype and 40 cases were non-GCB phenotype.The median follow-up time was 25 months.The two-year PFS and OS rates were 70.9％ and 89.5％,respectively.The two-year PFS and OS rates of chemotherapy alone group were 63.6％ and 85.0％,respectively;both were lower than those of combination of surgery and chemotherapy group (79.4％ and 94.7％),and the differences were statistically significant (x2 =4.232,P =0.040 and x2 =4.260,P =0.039).The two-year PFS and OS rates of GCB group were 68.8％ and 93.9％,respectively.And the two-year PFS and OS rates of non-GCB group were 73.2％ and 85.6％,respectively.There were no statistically significant differences between these two groups (both P ＞ 0.05).Among 41 patients with GCB type,25 were treated with combination of surgery and chemotherapy and 16 were treated with chemotherapy alone.The two-year PFS rate of patients treated with combination of surgery and chemotherapy (83.1％) was higher than that of patients treated with chemotherapy alone (49.2％),and the difference was statistically significant (x2 =5.627,P =0.018).The results of multivariate analysis indicated that treatment strategy was not an independent prognostic factor for all the enrolled patients and in patients with GCB type (all P ＞ 0.05).Conclusions Immunophenotypes may lack evaluation value of prognosis in patients with GI-DLBCL.Although among all the enrolled patients and patients with GCB type,the prognosis of patients treated with combination of surgery and chemotherapy is better than that of patients treated with chemotherapy alone,treatment strategy is not an independent prognostic factor.Multi-factors should be evaluated before selection of treatment strategy.

Objective To investigate the clinical value of radiomics nomogram,which is established by 18F-fluorodeoxyglucose (FDG) PET/CT radiomics signature combined with clinical-pathologic risk factors,in predicting the prognosis of patients with postoperative gastric carcinoma.Methods 18F-FDG PET/CT data of 207 patients (143 males,64 females,age range:20-85 years) with postoperative gastric carcinoma from January 2008 to August 2015 was reviewed retrospectively.Patients were divided into training group (n=104) and validation group (n =103),and the clinicopathologic information and disease-free survival (DFS) data were acquired.Significant textural features were selected from PET/CT images,and radiomics score (RS) for individual patient was calculated based on the radiomics signatures.The relationship between RS and DFS was analyzed.Cox regression analysis was performed to determine the risk factors ofDFS.The radiomics nomo-gram,obtained from combination of RS with clinicopathologic risk factors,was established and further evaluated in predictive value for recurrence or metastasis of postoperative gastric carcinoma,and the concordance index (C-index) was calculated.Results Cox regression analysis demonstrated that RS,tumor location,depth of invasion,lymph node metastasis,and distant metastasis were the significant risk factors for DFS (hazard ratios:2.148-2.828,all P＜0.05).The radiomics nomogram combined with RS and 4 clinicopathologic risk factors had a better prediction for the estimated DFS,comparing to RS alone.C-index of radiomics nomogram and RS were 0.830 and 0.700 in training group,and 0.776 and 0.681 in validation group,respectively.Conclusion Radiomics nomogram which is established by radiomics signatures and clinicopathologic risk factors may be better for predicting DFS of patients with postoperative gastric carcinoma.

Objective To analyze the causes of Crohn's disease (CD) misdiagnosed as intestinal malignancy by 18F-fluorodeoxyglucose (FDG) PET/CT.Methods The clinical and 18F-FDG PET/CT data of 70 CD patients (48 males,22 females;average age:(32.1± 16.7) years) confirmed pathologically from June 2010 to June 2016 in PET Center of Nanfang Hospital were retrospectively reviewed.Patients misdiagnosed as malignancy were selected.The locations,morphologic and metabolic features were retrospectively analyzed.Results Six of seventy CD cases were misdiagnosed as intestinal malignancy (maximum standardized uptake value (SUVmax):7.8-29.8).Among them,4 patients were misdiagnosed as colonic carcinoma and 2 patients were misdiagnosed as intestinal lymphoma.All the intestinal lesions in 6 patients were FDG-avid,4 patients that were misdiagnosed as colonic carcinoma presented as localized irregular mass with extra luminal wall air bubble sign on CT.Two cases that were misdiagnosed as intestinal lymphoma presented as segmental diffusive intestinal wall thickening companied with bowel stiffness,intestinal loops enlargement and finger-pressing pattern along the surface of the intestinal mucosa on CT.Conclusions FDG-avid CD presenting as single localized irregular mass or segmental diffusive intestinal thickening can mimic intestinal malignancy.CT features are useful for differential diagnosis and reducing diagnostic errors.

Objective To explore whether the prognostic efficiency of international prognostic index (IPI) can be further improved by interim 18F-fluorodeoxyglucose (FDG) PET/CT.Methods A total of 185 patients (116 males,69 females;average age 49 years) with pathologically confirmed diffuse large Bcell lymphoma (DLBCL) from January 2004 to January 2014 were enrolled in this retrospective study.The risk was classified by IPI (0-2 was considered as low risk,3-5 was considered as high risk) and all patients underwent 18F-FDG PET/CT scan before and after 4 cycles of immunochemotherapy.Based on interim 18 F-FDG PET/CT imaging,5-point Deauville score was used to reclassify DLBCL patient into negative group and positive group,and the interpretations were evaluated for 2-year progression-free survival (PFS) and overall survival (OS) rates.Kaplan-Meier analysis,log-rank test and Cox regression were used for data analysis.Results With a median follow-up of 27 (2-146) months,the 2-year PFS and OS rates were 60％(111/185) and 81％(150/185),respectively.A total of 114 patients were included in the low-risk group and 71 patients were in the high-risk group.Both 2-year PFS rates and OS rates between the 2 groups were statistically different:72％(82/114) vs 37％(26/71),x2=20.86,P＜0.01;90％(103/114) vs 63％(45/71),x2=13.39,P＜0.01.The interim PET/CT showed 113 patients with negative results and 72 patients with positive results,whose 2-year PFS rates and OS rates were also statistically different:82％ (93/113) vs 24％(17/72),x2 =66.66,P＜0.01;90％(102/113) vs 51％(37/72),x2 =33.11,P＜0.01.In the low-risk group,85 patients were PET-negative and 29 patients were PET-positive.The 2-year PFS rates were 88％ (75/85) and 31％(9/29),respectively (x2 =35.52,P＜0.01).The 2-year OS rates were 96％ (82/85) and 66％(19/29),respectively (x2 =11.88,P＜0.01).In the high-risk group,28 patients were PET-negative and 43 patients were PET-positive.The 2-year PFS and OS rates were 64％(18/28) vs 19％(8/43;x2 =17.33,P＜0.01) and 86％(24/28) vs 49％(21/43;x2=9.95,P＜0.01),respectively.Conclusions Both IPI and interim 18F-FDG PET/CT have the prognostic value for patients with DLBCL.Interim 18F-FDG PET/CT can improve the prognostic efficiency of IPI.

Objective To evaluated the value of PET conventional parameters and texture parameters in prediction of the Kirsten rat sarcoma viral oncogene (KRAS) gene expression status in colorectal cancer (CRC) by analyzing the relationship between those parameters and KRAS gene status. Methods From December 2012 to January 2017, 18 F-fluorodeoxyglucose (FDG) PET/ CT data and KRAS gene status of 58 CRC patients (40 males, 18 females, average age 56.31 years) before anti-tumor therapies were collected. The relation-ship between PET parameters and KRAS gene expression was analyzed. Receiver operating characteristic (ROC) curve analysis was used to evaluate the values of PET conventional parameters and texture parame-ters for predicting the KRAS gene status. Spearman rank correlation and Mann-Whitney u test were used to analyze the data. Results Of 58 CRC patients, 19(32.8％) had KRAS mutation, while 39(67.2％) were with wild type KRAS. Among the 46 PET image parameters extracted by Chang-Gung image texture analysis (CGITA), 14 PET image parameters were selected by Spearman rank correlation (all ︳rs︳>0.8), inclu-ding 12 texture parameters and 2 conventional parameters (maximum standardized uptake value (SUVmax ) and total lesion glycolysis (TLG)). Six PET image parameters (4 texture parameters and 2 conventional pa-rameters) were found to be different between KRAS gene mutant group and wild group (u values: from -4.481 to -2.046, all P < 0. 05). Among the 4 texture parameters, standardized uptake value ( SUV) kurtosis (SUVkur ) had the best prediction value, while SUVmax was the better one for prediction in the 2 conventional parameters. When 4.27 was selected as the cut-off value for SUVkur , the Youden index was up to the maxi-mum as 0. 35 and it yielded 0.667 on the area under curve (AUC) (95％ CI: 0.517-0.816, P = 0.041) with the sensitivity of 15/ 19 and specificity of 56.4％(22/ 39), respectively. When 16.6 was selected as the cut-off value of for SUVmax , the Youden index was up to the maximum as 0.64 and the AUC on predicting the KRAS mutant was 0.865 (95％ CI: 0.770-0.960, P<0.001) with the sensitivity of 17/ 19 and specifici-ty of 74.4％(29/ 39), respectively. The efficacy of SUVmax for predicting KRAS mutation was significantly better than that of SUVkur(z= 3.258, P= 0.001). Conclusion PET texture parameters and conventional pa-rameters can be used to predict the KRAS gene status in CRC patients, and SUVmax may be the best parameter.

Objective To investigate the imaging presentation of T-and NK/T-cell lymphomas with different pathology subtypes on 18F-FDG PET/CT.Methods A total of 95 patients (66 males, 29 females, average age 38.42 years) with T-and NK/T-cell lymphoma proved by pathology from June 2006 to February 2016 were retrospectively analyzed.18F-FDG uptake (SUVmax), nodal invasion, nodal distribution, extra-nodal involvement and staging were compared among 7 pathological subtypes of T-and NK/T-cell lymphomas.One-way analysis of variance, Fisher exact test and Kruskal-Wallis H test were used for data analysis.Results There were significant differences in terms of 18F-FDG uptake, nodal invasion, nodal distribution, extra-nodal involvement and staging among different pathological subtypes of T-and NK/T-cell lymphomas (F=2.937, P<0.05;Fisher exact test,all P<0.01;H=19.883, P<0.01).NK/T-cell lymphoma was found to be prone to invade the nasal cavity and nasopharynx, enteropathic type T-cell lymphoma was specific to the intestine, and subcutaneous panniculitis-like T-cell lymphoma presented with subcutaneous infiltration.All those 3 subtypes were quite specific in their extra-nodal involvement.Most patients with angioimmunoblastic T-cell lymphoma (ATCL), peripheral unspecified T-cell lymphoma (PUTCL) and T immunoblastic lymphoma (TIBL) presented as stage Ⅳ disease.Widespread lymph node disease associated with splenic, parotid and serous membrane involvement were often seen in ATCL patients (most commonly to involve the parotid glands and serous membrane among the 7 subtypes).Nodal involvement was found in PUTCL patients, but extranodal involvement was rather non-specific.TIBL had a non-specific pattern of nodal involvement with low 18F-FDG uptake, lower than ATCL and the other 5 subtypes.Anaplastic large cell lymphoma subtypes had the highest 18F-FDG uptake when compared with the other 6 subtypes, but were less often to manifest as stage Ⅳ disease despite their preponderance for marrow and nodal infiltration.Conclusion Different pathological subtypes of T-and NK/T-cell lymphoma manifest different imaging presentations on 18F-FDG PET/CT, which are useful for understanding their biological characteristics.