Objective:To determine if preoperative 68Ga-fibroblast activation protein inhibitor (FAPI)-04 PET/MR could contribute to predicting pathological complete response (pCR) in patients with gastrointestinal cancer undergoing neoadjuvant immunotherapy. Methods:In this retrospective study, 35 patients (23 males, 12 females, age (59.1±7.9) years) with gastrointestinal cancer who underwent 68Ga-FAPI-04 PET/MR after receiving neoadjuvant immunotherapy between February 2021 and January 2024 were enrolled. Clinical data, PET imaging parameters including SUV, peak of SUV normalized by lean body mass (SUL peak), FAPI-positive tumor volume (FTV), and total FAPI-positive lesion burden (TLF), and pathological data were collected and analyzed. Patients were divided into pCR group and non-pCR group, and the independent-sample t test or Mann-Whitney U test was performed to compare those parameters between the 2 groups. ROC curve analysis (Delong test) was performed to evaluate the diagnostic efficiency of each parameter to predict pCR. Results:The overall pCR rate of the neoadjuvant therapy was 40.0%(14/35). In the visual evaluation, 68Ga-FAPI-04 PET was limited in predicting pCR, showing false positivity in 12 patients and false negative in 1 patent. While SUV max( t=2.50, P=0.018), SUL peak( t=3.11, P=0.004), FTV( U=3.00, P=0.030) and TLF( U=2.96, P=0.042) in non-pCR group were all higher than those in pCR group. The predictive efficiency of FTV <1.925cm 3 for pCR was better than the efficiency of PET visual evaluation ( Z=3.61, P<0.001), with the prediction accuracy of 82.86%(29/35). Conclusions:68Ga-FAPI-04 PET/MR may provide an effective clinical tool for guiding further treatment of patients with gastrointestinal cancer undergoing neoadjuvant immunotherapy. The quantitative features derived from 68Ga-FAPI-04 PET appear promising in predicting pCR, which are expected to provide a reference for avoiding surgery.

Objective:To evaluate the clinical value of 11C-methyl- L-methionine (MET) PET/MR in the differential diagnosis between neoplastic and non-neoplastic brain lesions. Methods:From July 2017 to May 2022, a total of 34 patients (19 males, 15 females, age 8-81 years) who received 11C-MET PET/MR imaging for suspected brain tumors in Union Hospital, Tongji Medical College, Huazhong University of Science and Technology were retrospectively enrolled. Postoperative pathological or clinical follow-up results were used as the gold standard. Diagnostic performance of 11C-MET PET/MR and contrast-enhanced MRI was evaluated by ROC curve analysis and Delong test, as well as the diagnostic performance of PET metabolic parameters (SUV and target to background ratio (TBR)), MRI multi-sequence parameters (cerebral blood flow (CBF), relative CBF (rCBF), apparent diffusion coefficient (ADC), relative ADC (rADC), choline/creatine (Cho/Cr) and choline/ N-acetylaspartate (Cho/NAA)) and their combination. Results:A total of 35 lesions of 34 patients were enrolled, including 12 (34.3%) non-neoplastic lesions and 23(65.7%) neoplastic lesions. The diagnostic sensitivity, specificity, and accuracy for 11C-MET PET/MR were 91.3%(21/23), 12/12, and 94.3%(33/35), in contrast to 16/18, 2/10, and 64.3%(18/28) for contrast-enhanced MRI. Maximum TBR (TBR max) showed the highest discriminative value (AUC=0.877, 95% CI: 0.692-1.000). The combination of TBR max, minimum ADC (ADC min), rCBF, and Cho/NAA could achieve a higher diagnostic performance (AUC=0.918, 95% CI: 0.816-1.000), although the difference was not statistically significant ( Z=-0.42, P=0.676). Conclusion:Multiple quantitative parameters of 11C-MET PET/MR are beneficial to distinguish neoplastic from non-neoplastic brain lesions, and their combination may improve the diagnostic confidence.

Objective:To determine if preoperative 68Ga-fibroblast activation protein inhibitor (FAPI)-04 PET/MR could contribute to predicting pathological complete response (pCR) in patients with gastrointestinal cancer undergoing neoadjuvant immunotherapy. Methods:In this retrospective study, 35 patients (23 males, 12 females, age (59.1±7.9) years) with gastrointestinal cancer who underwent 68Ga-FAPI-04 PET/MR after receiving neoadjuvant immunotherapy between February 2021 and January 2024 were enrolled. Clinical data, PET imaging parameters including SUV, peak of SUV normalized by lean body mass (SUL peak), FAPI-positive tumor volume (FTV), and total FAPI-positive lesion burden (TLF), and pathological data were collected and analyzed. Patients were divided into pCR group and non-pCR group, and the independent-sample t test or Mann-Whitney U test was performed to compare those parameters between the 2 groups. ROC curve analysis (Delong test) was performed to evaluate the diagnostic efficiency of each parameter to predict pCR. Results:The overall pCR rate of the neoadjuvant therapy was 40.0%(14/35). In the visual evaluation, 68Ga-FAPI-04 PET was limited in predicting pCR, showing false positivity in 12 patients and false negative in 1 patent. While SUV max( t=2.50, P=0.018), SUL peak( t=3.11, P=0.004), FTV( U=3.00, P=0.030) and TLF( U=2.96, P=0.042) in non-pCR group were all higher than those in pCR group. The predictive efficiency of FTV <1.925cm 3 for pCR was better than the efficiency of PET visual evaluation ( Z=3.61, P<0.001), with the prediction accuracy of 82.86%(29/35). Conclusions:68Ga-FAPI-04 PET/MR may provide an effective clinical tool for guiding further treatment of patients with gastrointestinal cancer undergoing neoadjuvant immunotherapy. The quantitative features derived from 68Ga-FAPI-04 PET appear promising in predicting pCR, which are expected to provide a reference for avoiding surgery.

Objective:To evaluate the clinical value of 11C-methyl- L-methionine (MET) PET/MR in the differential diagnosis between neoplastic and non-neoplastic brain lesions. Methods:From July 2017 to May 2022, a total of 34 patients (19 males, 15 females, age 8-81 years) who received 11C-MET PET/MR imaging for suspected brain tumors in Union Hospital, Tongji Medical College, Huazhong University of Science and Technology were retrospectively enrolled. Postoperative pathological or clinical follow-up results were used as the gold standard. Diagnostic performance of 11C-MET PET/MR and contrast-enhanced MRI was evaluated by ROC curve analysis and Delong test, as well as the diagnostic performance of PET metabolic parameters (SUV and target to background ratio (TBR)), MRI multi-sequence parameters (cerebral blood flow (CBF), relative CBF (rCBF), apparent diffusion coefficient (ADC), relative ADC (rADC), choline/creatine (Cho/Cr) and choline/ N-acetylaspartate (Cho/NAA)) and their combination. Results:A total of 35 lesions of 34 patients were enrolled, including 12 (34.3%) non-neoplastic lesions and 23(65.7%) neoplastic lesions. The diagnostic sensitivity, specificity, and accuracy for 11C-MET PET/MR were 91.3%(21/23), 12/12, and 94.3%(33/35), in contrast to 16/18, 2/10, and 64.3%(18/28) for contrast-enhanced MRI. Maximum TBR (TBR max) showed the highest discriminative value (AUC=0.877, 95% CI: 0.692-1.000). The combination of TBR max, minimum ADC (ADC min), rCBF, and Cho/NAA could achieve a higher diagnostic performance (AUC=0.918, 95% CI: 0.816-1.000), although the difference was not statistically significant ( Z=-0.42, P=0.676). Conclusion:Multiple quantitative parameters of 11C-MET PET/MR are beneficial to distinguish neoplastic from non-neoplastic brain lesions, and their combination may improve the diagnostic confidence.

Objective:To evaluate the diagnostic efficacy of the multiparametric MRI (mpMRI) deep learning artificial intelligence (AI) analysis system combined with 68Ga-prostate specific membrane antigen (PSMA) PET for prostate cancer. Methods:Data of 103 patients (age: 45-85 years) who underwent 68Ga-PSMA PET/MR at Union Hospital, Tongji Medical College, Huazhong University of Science and Technology from May 2018 to October 2023 for suspected or confirmed prostate cancer were retrospectively collected. ROI was delineated to measure SUV max of primary tumor or prostate, and a deep learning AI system was applied to analyze MR images of the prostate. The diagnostic efficacies of T 2 weighted imaging (WI), diffusion WI (DWI), mpMRI, PET SUV max, and PET/MR for prostate cancer were assessed, with using the pathological results as the gold standard. Results:Among 103 patients, 82 cases (79.61%) were with prostate cancer. PET unimodality demonstrated the best specificity (100%, 21/21), positive predictive value (100%, 58/58), and AUC (0.860, 95% CI: 0.777-0.920). The mpMRI AI analysis provided rapid diagnostic results and the sensitivity and accuracy were improved by combining with PET (sensitivities of PET, mpMRI and the combination of the two were 70.73%(58/82), 86.59%(71/82), and 92.68%(76/82), respectively; the accuracies were 76.70%(79/103), 81.55%(84/103) and 86.41%(89/103), respectively). Among 44 patients with negative PET, 30 patients received an accurate diagnosis when the results of mpMRI AI analysis were added. Conclusions:68Ga-PSMA PET demonstrates good specificity for prostate cancer and mpMRI AI analysis is time-saving. The combined application improves the diagnostic sensitivity and accuracy, which provides a valuable tool for 68Ga-PSMA PET/MR image analysis.

Objective:To investigate the diagnostic and prognostic value of 68Ga-fibroblast activation protein inhibitor (FAPI) PET for hepatobiliary malignancies. Methods:From July 2020 to February 2023, 33 patients (23 males, 10 females; age (55.4±13.5) years) with suspected or confirmed liver or biliary tract malignancies who underwent 68Ga-FAPI PET in Union Hospital, Tongji Medical College, Huazhong University of Science and Technology were retrospectively analyzed. PET images were evaluated by 3 experienced nuclear medicine physicians, and the results of biopsy or postoperative pathology, clinical and imaging follow-up were used as the gold standard. One-way analysis of variance and least significant difference t test were used to compare the differences among groups. Survival analysis was performed using Kaplan-Meier curves and the log-rank test. Results:Of 33 patients, 14 performed PET for initial diagnosis and staging, and 19 for restaging. There were 14 patients with hepatocellular carcinoma (HCC), 13 patients with cholangiocarcinoma (CCA), and 6 patients with gallbladder carcinoma (GBC). The primary tumor of HCC, CCA and GBC all showed significant 68Ga-FAPI uptake, with no statistically significant difference in SUV max among groups ( F=1.58, P=0.250). The sensitivities of 68Ga-FAPI PET for initial diagnosis and restaging of hepatobiliary malignancies were 14/14 and 15/15, respectively. Compared with conventional imaging, 68Ga-FAPI PET changed the diagnosis and staging in 29.2%(7/24) patients. The treatment strategy was changed in 30.3%(10/33) patients with malignant tumors due to 68Ga-FAPI PET findings. Follow-up showed 22 cases survived and 11 cases died, with the overall survival of 355.56(80.00, 516.97) d, and 1- and 2-year survival rates were 68.2% and 57.9%, respectively. Semi-quantitative 68Ga-FAPI PET parameters such as SUV max, target-liver ratio (TLR), and target-blood ratio (TBR) had no significant prognostic value, but the prognosis of the group without distant metastases diagnosed by 68Ga-FAPI PET was significantly better than that of the group with distant metastasis ( P=0.032). Conclusion:68Ga-FAPI PET has high sensitivity for the diagnosis of hepatobiliary malignancies, which can help guide treatment decisions and prognosis evaluation.

Objective:To explore the feasibility of pretargeting technique for immunoPET with epidermal growth factor receptor (EGFR) monoclonal antibody in EGFR positive/negative tumor bearing mice.Methods:Cetuximab- Trans-cyclooctene (TCO)was obtained by modifying Cetuximab with TCO- N-hydroxysuccinimide (NHS). 2, 2′-((6-amino-1-(4, 7-bis-(carboxymethyl)-1, 4, 7-triazonan-1-yl)hexan-2-yl)azanediyl)-diacetic acid (L-NETA)was used as a chelating agent to prepare the radioligand 68Ga-L-NETA-tetrazine (Tz), then the labeling rate and in vitro stability of the product were determined. Human basal breast cancer cells MDA-MB-468 (EGFR+ ) and MDA-MB-231 (EGFR-) were cultured in vitro. In vitro experiments were performed to explore the specificity of the probe and the feasibility of pretargeting technique. Nude mice (Balb/c-nu) bearing xenografts of the above two cell lines were established. Cetuximab-TCO (50 μg) was injected into the tumor-bearing mice in advance, then 68Ga-L-NETA-Tz was injected at different time points (48, 36, 24 and 12 h), and pretargeting was realized through " click chemistry" . Small-animal PET imaging and biodistribution were performed to evaluate pharmacokinetic properties and specificity of the probe. The one-way analysis of variance was used to compare the data. Results:The 68Ga-L-NETA-Tz molecular probe was successfully prepared with the labeling yield >95%, and the radiochemical purity was >95% after 2 h. Cetuximab-TCO and 68Ga-L-NETA-Tz were added to MDA-MB-468 cells successively, and the cell uptake rate reached (0.69±0.04)% at 1 h, which demonstrated the feasibility of the pretargeting technique. PET imaging and biodistribution results showed that the best imaging results were obtained in 36 h pre-injection group, in which the tumor uptake was the highest ((0.77±0.05) percentage activity of injection dose per gram of tissue (%ID/g), 1 h) and the tumor/muscle ratio was optimal (4.67±0.46); the tumor uptake in the blocking group, the group without injecting Cetuximab-TCO, and the MDA-MB-231 group were significantly lower ((0.35±0.01), (0.39±0.05), (0.45±0.10) %ID/g; F=15.50, P=0.002). Conclusions:EGFR targeted immunoPET imaging is successfully performed in mouse models of breast cancer by injecting Cetuximab-TCO and 68Ga-L-NETA-Tz successively. It provides an effective method for immunoPET imaging of monoclonal antibodies.

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.

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.

Objective:To explore the feasibility and conditions of in vitro and in vivo imaging of triple-negative breast cancer using visible light emitted quantum dots(QDs) as the carrier to target epidermal growth factor receptor (EGFR). Methods:The water-soluble QDs reacted with Cetuximab to synthesize the probe QD-Cetuximab. The morphology, particle size, stability and luminescence properties of the probe were examined. Human breast cancer cells MDA-MB-468 (EGFR+ ) and MDA-MB-453 (EGFR-) were cultured. Cytotoxicity assays, in vitro imaging and fluorescence intensity quantification were performed after cells incubation with QD-Cetuximab and QDs. Eight MDA-MB-468 tumor-bearing mice models were constructed, 100 μl QD-Cetuximab and QDs were injected through the tail vein. In vivo imaging and probe distribution were obtained at different time points. Independent-sample t test was used to analyze the data. Results:QD-Cetuximab had a particle size of (40.34±2.44) nm detected by transmission electron microscope (TEM), a hydrated particle size of (57.85±4.69) nm detected by dynamic light scattering (DLS), and a stable structure. When the concentration of QD-Cetuximab was ≤50 nmol/L, the relative survival rate of cells was more than 90%, and when the concentration exceeded 100 nmol/L, the relative survival rate of cells was reduced to (72.52±4.91)% ( P<0.05). The red fluorescence of MDA-MB-468 incubated with QD-Cetuximab was stronger than that of MDA-MB-468 incubated with QDs and MDA-MB-453 incubated with QD-Cetuximab or QDs. The confocal fluorescent intensity quantitative determination showed that the ratio of QD-Cetuximab group/QDs group was 5.1 (863.36/169.97). Flow cytometry showed that the uptake of QD-Cetuximab and QDs by MDA-MB-468 increased with incremental incubating concentration, and the former was more significantly( t values: 12.25-38.11, all P<0.05). When the incubating concentration was 25, 50, 100, and 200 nmol/L, the quantitative average fluorescent intensity ratio of QD-Cetuximab group/QDs group was 5.4, 6.9, 7.4 and 6.2, respectively. The QD-Cetuximab and QDs probes mainly accumulated in the liver in vivo. The fluorescence emitted by tumor was not obvious under the high fluorescence of liver as a background. However, the fluorescence was visible in the isolated tumor tissue, and the quantitative fluorescence intensity of experimental group and control group were (2.46±0.60)×10 4 and (1.29±0.05)×10 4, respectively ( t=3.392, P=0.015). Conclusions:Cetuximab can increase the targeting ability of QDs and promote cell uptake. Although the isolated tumor imaging results are acceptable, further modification of QDs should be considered to reduce the liver uptake and improving in vivo fluorescence imaging efficiency.