Thoughts on the timing of targeted therapy initiation for thyroid cancer / 中华核医学与分子影像杂志

The treatment of persistent/recurrent and metastatic thyroid cancer and medullary thyroid cancer has made significant progress through the use of molecule-targeted therapy. While this approach has shown promise in improving patient outcomes and clinical symptoms, it also carries potential risks. The primary focus and challenge of targeted therapy is to optimize benefits while managing risks within predetermined thresholds. This review examines current targeted treatment practices in thyroid cancer and investigates the correlation between the timing of targeted therapy initiation and the patient benefits, aiming to lay the groundwork for subsequent research.

Radiomics in nasopharyngeal carcinoma: current progress and challenges / 中华核医学与分子影像杂志

Nasopharyngeal carcinoma (NPC) is one of the most common malignant tumors of the head and neck. In clinical practice, imaging examination plays an important role in the diagnosis, staging and risk assessment of NPC. However, it is difficult to distinguish the heterogeneity within the tumor, so the ability to classify and predict NPC is limited. Radiomics can extract a large amount of data from medical images for quantitative analysis, which further improves the ability of imaging features to diagnose and predict tumors. The purpose of this review is to introduce the application value of radiomics of different imaging modality such as CT, MRI and PET in differential diagnosis, predictions of treatment response, prognosis and radiotherapy complications of NPC.

Diagnostic and prognostic value of 68Ga-FAPI PET for malignant tumors of the liver and biliary tract / 中华核医学与分子影像杂志

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.

Interpretation of presynaptic dopaminergic PET imaging results / 中华核医学与分子影像杂志

Presynaptic dopaminergic PET imaging is a useful method for the diagnosis of parkinsonism. Based on the expert consensus on operation and clinical application of dopamine transporter brain PET imaging technology published in 2020, this paper further recommends the relevant elements of result interpretation of presynaptic dopaminergic PET imaging.

Predictive values of 18F-FDG PET/CT image feature and metabolic parameters for the malignant potential of gastrointestinal stromal tumor / 中华核医学与分子影像杂志

Objective:To investigate the predictive values of 18F-FDG PET/CT image feature and metabolic parameters for the malignant potential of gastrointestinal stromal tumor (GIST). Methods:From March 2014 to June 2020, the 18F-FDG PET/CT imaging and surgical pathological data of 35 patients with GIST (27 males, 8 females; age 44-84 years) from Union Hospital, Tongji Medical College, Huazhong University of Science and Technology and Zhongnan Hospital of Wuhan University were analyzed retrospectively. Patients were divided into ring-shaped uptake group and other uptake patterns group according to 18F-FDG PET/CT image feature. Fisher′s exact test was used to analyze the differences of tumor necrosis and National Institutes of Health (NIH) risk classification (short for NIH classification) between different image feature groups. Mann-Whitney U test was used to analyze the differences of SUV max , metabolic parameters at different thresholds (2.5, 40%, 50%) of SUV max (metabolic tumor volume (MTV; MTV 2.5, MTV 40%, MTV 50%) and total lesion glycolysis (TLG; TLG 2.5, TLG 40%, TLG 50%)) between different clinicopathological features (lesion location, tumor diameter, mitotic count, Ki-67, necrosis, image feature, NIH classification) groups. Spearman rank correlation analysis was used to explore the correlation between clinicopathological features and metabolic parameters. ROC curve analysis was used to distinguish NIH classification of different metabolic parameters. Delong test was used to compared differences between different AUCs. Results:Of 35 GIST patients, 11(31.4%) were ring-shaped uptake and 24(68.6%) were other uptake patterns, and the differences of necrosis (7/11 vs 12.5%(3/24); P=0.004) and NIH classification (11/11 vs 25.0%(6/24); P<0.001) between the two groups were significant. There were significant differences of metabolic parameters between different groups of tumor diameter, mitotic count, necrosis, image feature, NIH classification ( z values: from -4.70 to -2.09, all P<0.05), while there were no significant differences of Ki-67 ( z values: from -0.83 to -0.71, all P>0.05). Metabolic parameters were correlated with mitotic count, tumor diameter, necrosis, image feature and NIH classification ( rs values: 0.36-0.81, all P<0.05), while was not correlated with Ki-67 ( rs values: 0.12-0.14, all P>0.05). The differences of AUCs between SUV max and MTV 2.5, TLG 2.5, TLG 40%, TLG 50%were significant (0.752, 0.856, 0.856, 0.882, 0.886; z values: 1.96-2.12, all P<0.05). Conclusions:The NIH classification of GIST with ring-shaped uptake on 18F-FDG PET/CT is higher and more prone to necrosis. The 18F-FDG PET/CT metabolic parameters based on different thresholds of SUV max have certain significance for the prediction of NIH classification of GIST, and may be superior to SUV max.

18F-FDG hybrid PET/MR radiomics based on different segmentation methods for distinguishing Parkinson′s disease from multiple system atrophy / 中华核医学与分子影像杂志

Objective:To explore the impact of different segmentation methods on differential diagnostic efficiency of 18F-FDG PET/MR radiomics to distinguish Parkinson′s disease (PD) from multiple system atrophy (MSA). Methods:From December 2017 to June 2019, 90 patients (60 with PD and 30 with MSA; 37 males, 53 females; age (55.8±9.5) years) who underwent 18F-FDG PET/MR in Union Hospital, Tongji Medical College, Huazhong University of Science and Technology were retrospectively collected. Patients were randomized to training set and validation set in a ratio of 7∶3. The bilateral putamina and caudate nuclei, as the ROIs, were segmented by automatic segmentation of brain regions based on anatomical automatic labeling (AAL) template and manual segmentation using ITK-SNAP software. A total of 1 172 radiomics features were extracted from T 1 weighted imaging (WI) and 18F-FDG PET images. The minimal redundancy maximal relevance (mRMR) and least absolute shrinkage and selection operator (LASSO) algorithm were used for features selection and radiomics signatures (Radscore) construction, with 10-fold cross-validation for preventing overfitting. The diagnostic performance of the models was assessed by ROC curve analysis, and the differences between models were calculated by Delong test. Results:There were 63 cases in training set (42 PD, 21 MSA) and 27 cases in validation set (18 PD, 9 MSA). The Radscore values were significantly different between the PD group and the MSA group in all training set and validation set of radiomics models ( 18F-FDG_Radscore and T 1WI_Radscore) based on automatic or manual segmentation methods ( z values: from -5.15 to -2.83, all P<0.05). ROC curve analysis showed that AUCs of 18F-FDG_Radscore and T 1WI_Radscore based on automatic segmentation in training and validation sets were 0.848, 0.840 and 0.892, 0.877, while AUCs were 0.900, 0.883 and 0.895, 0.870 based on manual segmentation. There were no significant differences in training and validation sets between Radiomics models based on different segmentation methods ( z values: 0.04-0.77, all P>0.05). Conclusions:The 18F-FDG PET/MR radiomics models based on different segmentation methods achieve promising diagnostic efficacy for distinguishing PD from MSA. The radiomics analysis based on automatic segmentation shows greater potential and practical value in the differential diagnosis of PD and MSA in view of the advantages including time-saving, labor-saving, and high repeatability.

Application of artificial intelligence in PET/CT for the therapy prediction and prognosis evaluation of malignant tumors / 中华核医学与分子影像杂志

PET plays an important role in diagnosis, staging, treatment response assessment, recurrence surveillance, follow-up and treatment guidance for the malignancy. Artificial intelligence is the scientific fields using computer and other advanced technologies to simulate human intelligent behaviors and critical thinking, among which machine learning and deep learning are most widely used in medicine. Available big data, the progress of computer science and computational capabilities facilitate the application of artificial intelligence in image analysis. This article reviews the current clinical application research of artificial intelligence in PET/CT imaging used for prognosis and prediction of malignant tumors, and puts forward current challenges and prospects for the future.

Guidance for operation and reading of 18F-FDG PET brain imaging in dementia / 中华核医学与分子影像杂志

Due to the availability of 18F-FDG in PET centers, this article aims to advocate and promote the standardization of 18F-FDG PET brain imaging in dementia in order to improve the reliability, repeatability and comparison of the imaging process and results. It is also provided to guide the PET imaging operation standard and to give suggestions on image interpretation.

Quality control of the multi-centre clinical trial on PET/CT brain imaging / 中华核医学与分子影像杂志

Multi-centre clinical trials on PET/CT brain imaging are complex to organize and require careful co-ordination and management. This article describes considerations, which are necessary when designing and starting a multi-centre clinical trial on PET/CT brain imaging, based on guidelines and multi-center clinical brain imaging studies, providing references for further studies.

Clinical research progress on radiopharmaceuticals imaging targeting epidermal growth factor receptor / 中华核医学与分子影像杂志

Epidermal growth factor receptor (EGFR) plays an important role in the development and occurrence of a variety of malignant tumors. Molecular targeted therapy for EGFR is in the ascendant. Molecular imaging can reveal the expression of EGFR and its mutations in vivo. The molecular probes labeled with 89Zr, 11C and 18F are used for imaging and the main research is about tyrosine kinase inhibitors labeled with 11C. PET is used to visualize EGFR expression and mutations in vivo, which can noninvasively screen patients suitable for targeting treatment and evaluate efficacy. This paper reviews the clinical researches and trials of these probes, and summarizes the clinical value of imaging methods, hoping to provide the evidence for clinical translation and application in the future.

Clinical application of 99Tc m-sulfur colloid lymphoscintigraphy in the diagnosis of lower limb lymphedema after gynecological tumor surgery / 肿瘤研究与临床

Objective:To explore the significance of 99Tc m-sulfur colloid lymphoscintigraphy in the diagnosis of lower limb lymphedema after gynecological tumor surgery. Methods:The clinical data of patients with lower limb lymphedema after gynecological tumor surgery in Union Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology from May 2015 to October 2019 were retrospectively analyzed. 99Tc m-sulfur colloid lymphoscintigraphy was performed in all patients. The results of lymphatic vessel imaging, lymph node imaging and their combination in the diagnosis of lower limb lymphedema were analyzed. The diagnostic efficacy of lymphatic vessel imaging alone, lymph node imaging alone and their combination was evaluated by the receiver operating characteristic (ROC) curve and the area under the curve (AUC), and the Youden index, sensitivity and specificity were calculated. Results:Among the 100 lower limbs of 50 patients, 56 limbs had lymphedema and 44 limbs had no obvious edema. When diagnosis was based on abnormal lymphatic vessel imaging alone, among 56 lower limbs with lymphedema, lower limbs lymphatic vessel imaging was positive in 38 (67.9%) and negative in 18 (32.1%); among 44 lower limbs without obvious edema, lower limbs lymphatic vessel imaging was positive in 6 (13.6%) and negative in 38 (86.4%); the sensitivity was 67.9%, the specificity was 86.4%, and the Youden index was 0.543. When diagnosis was based on abnormal lymph node imaging alone, among 56 lower limbs with lymphedema, lower limbs lymph node imaging was positive in 42 (75.0%) and negative in 14 (25.0%); among 44 lower limbs without obvious edema, lower limbs lymph node imaging was positive in 13 (29.5%) and negative in 31 (70.5%); the sensitivity was 75.0%, the specificity was 70.5%, and the Youden index was 0.455. When diagnosis was based on the combination of lymphatic vessel imaging and lymph node imaging, among 56 lower limbs with lymphedema, lymphatic vessel imaging and lymph node imaging were positive in 48 (85.7%) and negative in 8 (14.3%); among 44 lower limbs without obvious edema, lymphatic vessel imaging and lymph node imaging were positive in 14 (31.8%) and negative in 30 (68.2%); the sensitivity was 85.7%, the specificity was 68.2%, and the Youden index was 0.539. The AUC for the combined diagnosis of lymphatic vessel imaging and lymph node imaging was 0.781, the AUC for the diagnosis of abnormal lymphatic vessel imaging was 0.771, and the AUC for the diagnosis of abnormal lymph node imaging was 0.739 (all P < 0.01). Conclusions:99Tc m-sulfur colloid lymphoscintigraphy is of great help in the diagnosis of lower limb lymphedema after operation of gynecological tumors. The combination of lymph node imaging and lymphatic vessel imaging is more effective in the diagnosis of lower limb lymphedema.

Application and prospect of the MOOC of Nuclear Medicine resource in teaching for undergraduates / 中华核医学与分子影像杂志

Massive open online course (MOOC), as an online teaching mode, has attracted widespread attention in the education field. It realizes the integration of online teaching and learning in medical education and brings profound changes in concepts and methods of medical education. It has proposed a new development direction for modern medical education. The first Nuclear Medicine online MOOC resource is not only a supplement to direct face-to-face courses in a special period, but also a strong support for the realization of online and offline hybrid teaching, thereby promoting the " student-centered" undergraduates′ autonomous learning ability. The students can achieve the goal of the development of learning ability. Based on the results of applying the Nuclear Medicine MOOC to the teaching of undergraduates in multiple schools, this article further explains the obvious advantages of MOOC as an online teaching resource library for students′ knowledge internalization. The foundation of the new teaching method ensures the effective implementation of the above teaching methods and provides ideas for further deepening the reform of undergraduate medical education.

Pretargeted immunoPET imaging with epidermal growth factor receptor monoclonal antibody in mouse models / 中华核医学与分子影像杂志

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.

The application of molecular imaging in Parkinson′s disease / 中华神经科杂志

Parkinson′s disease (PD) is a common neurodegenerative disease, but due to the lack of reliable biomarkers, the clinical diagnosis of PD is challenging. Molecular imaging technology is a new technology which combines molecular biology technology with modern medical imaging. In recent years, the role of molecular imaging technology in the diagnosis and differential diagnosis of PD has been supported by more and more evidences, which can provide an important basis for the early diagnosis and differential diagnosis of PD. Although the research results of molecular imaging in the diagnosis and differential diagnosis of PD are increasing, the clinical application is still insufficient. Therefore, it is necessary to understand the research status of molecular imaging technology, and explore the future development direction, in order to make more rational use of this technology and better serve the clinical practice.

Diagnostic value of 68Ga-FAPI PET for restaging and its impact on treatment decision in patients with colorectal cancer / 中华核医学与分子影像杂志

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.

Research progress of radionuclide labeled fibroblast activation protein targeted molecular probes / 中华核医学与分子影像杂志

Fibroblast activation protein (FAP) is a marker protein of cancer-associated fibroblasts(CAFs). It is highly expressed in more than 90% of epithelial cancers and hardly expressed in normal tissues. Therefore, FAP is a very promising target. Radionuclide labeled FAP targeted molecular probes can be used for PET or SPECT imaging. In particular, 68Ga-FAP inhibitors (FAPIs) PET/CT has shown good prospects in the clinic, providing a new idea for early diagnosis, accurate staging and radionuclide treatment of tumors. In addition, FAP is also highly expressed in certain non-tumor diseases, especially those related to fibrosis. In this article, the research progress of radionuclide-labeled FAP targeted molecular probes is reviewed.

Renal depth measured by CT optimize the glomerular filtration rate using Gates method / 中华核医学与分子影像杂志

Objective:To explore the application value of CT measurement of renal depth correction, optimized acquisition and post-processing in the measurement of renal glomerular filtration rate (GFR) by Gates renal dynamic imaging.Methods:From January 2018 to November 2019, 157 patients (102 males, 55 females, age (51.4±14.5) years) including 118 in normal renal area group (adults with normal renal position and morphology, and excluding hydronephrosis, renal occupation, retroperitoneal mass and other factors affecting renal depth) and 39 in abnormal renal area group (19 of transplanted kidney, 11 of horseshoe kidney and 9 of ectopic kidney), were retrospectively enrolled in Union Hospital, Tongji Medical College, Huazhong University of Science and Technology. The GFR was measured by renal dynamic imaging Gates method. For the normal renal area group, the renal depth was calculated by CT method, the traditional Tonnesen formula or the Li Qian formula. For the abnormal renal area group, the GFR was measured by optimized acquisition and post-processing method (GFR optimization), the traditional post-processing method (GFR tradition), or Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula method (eGFR). The differences of the renal depth and corresponding GFR obtained by different methods were analyzed using one-way analysis of variance and the least significant difference (LSD) t test. The correlation was analyzed by Pearson correlation analysis, and the consistency was analyzed by Bland-Altman analysis. Results:In the normal renal area group, the left and right renal depth measured by CT were (7.40±1.43) and (7.51±1.37) cm. Tonnesen formula underestimated renal depth (left kidney: (6.03±0.82) cm, right kidney: (6.06±0.84) cm; F values: 64.145 and 68.567, both P<0.01), and the deviation increased with the increase of CT measured depth ( r values: 0.847 and 0.834, both P<0.01). The GFR measured by Tonnesen formula was (56.93±28.42) ml·min -1·1.73 m -2, and the difference was statistically significant compared with CT method ((73.43±36.56) ml·min -1·1.73 m -2; F=9.423, P<0.01). The renal left and right depth measured by Li Qian formula were (7.55±1.03) and (7.52±0.98) cm, and the total GFR was (73.65±34.50) ml·min -1·1.73 m -2 with no differences compared with CT method (all P>0.05). The GFR obtained by Li Qian formula had better correlation ( r=0.901, P<0.01) and consistency with CT method. In the abnormal renal area group, GFR optimization, GFR tradition and eGFR was (63.11±27.40), (48.40±25.45) and (59.89±32.24) ml·min -1·1.73 m -2, respectively, and the difference between GFR tradition and GFR optimization was statistically significant ( F=2.870, P=0.025). GFR optimization had better correlation ( r=0.941, P<0.01) and consistency with eGFR. Conclusions:Tonnesen formula underestimates the renal depth. Using CT to measure renal depth and perform depth correction can improve the accuracy of Gates method for GFR determination. For the special cases of transplanted kidney, horseshoe kidney, ectopic kidney and retroperitoneal mass, it is important to optimize acquisition scheme and post-processing method to obtain accurate GFR.

Visible light emitted quantum dots targeting EGFR in triple-negative breast cancer / 中华核医学与分子影像杂志

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.

Study of statistical parametric mapping aided semi-quantitative analysis of 11C-PIB PET imaging acquired by hybrid PET/MR and its clinical application / 中华核医学与分子影像杂志

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.

Room construction and installation of integrated PET/MR / 中华核医学与分子影像杂志

The integrated PET/MR overcomes the problem of interferences between PET and the strong magnetic field of MRI, realizing the simultaneous acquisition of two modalities, which is a milestone in the field of medical imaging. The use of PET/MR requires the radiopharmaceutical as well as avoids interferences to the homogeneity of main magnetic field and stability of radio-frequency field from surrounding environment. Therefore, the site selection and layout design about integrated PET/MR are more complicated than the single mode system, and the results of installation and debugging should satisfy two imaging modalities (imaging quality and quantitative accuracy). In this paper, the room construction, installation and debugging of integrated PET/MR are discussed, which can supply a reference about key issues in the construction of similar projects.