Medical whole-body positron emission tomography (PET), one of the most successful molecular imaging technologies, has been widely used in the fields of cancer diagnosis, cardiovascular disease diagnosis and cranial nerve study. But, on the other hand, the sensitivity, spatial resolution and signal-noise-ratio of the commercial medical whole-body PET systems still have some shortcomings and a great room for improvement. The sensitivity, spatial resolution and signal-noise-ratio of PET system are largely affected by the performances of the scintillators and the photo detectors. The design of a PET system is usually a trade-off in cost and performance. A better image quality can be achieved by optimizing and balancing the key components which affect the system performance the most without dramatically increases in cost. With the development of the scintillator, photo-detector and high speed electronic system, the performance of medical whole-body PET system would be dramatically improved. In this paper, we report current progresses and discuss future directions of the developments of technologies in medical whole-body PET system.
In the process of positron emission tomography (PET) data acquiring, respiratory motion reduces the quality of PET imaging. In this paper, we present a correction method using three level grids B-spline elastic method to correct denoised and reorganized sinograms for respiratory motion correction. Using GATE simulates NCAT respiratory motion model to generate raw data which are used in experiment, the experiment results showed a significantly improved respiratory image with higher quality of PET, and the motion blur and structural information were fixed. The results proved the method of this paper would be effective for the elastic registration.
Objective To investigate the accuracy of 18F-FDG positron emission tomography/computed tomography (PET/CT) combined with CT three-dimensional reconstruction (CT-3D) in the differential diagnosis of benign and malignant pulmonary nodules. Methods The clinical data of patients who underwent pulmonary nodule surgery in the Department of Thoracic Surgery, Northern Jiangsu People's Hospital from July 2020 to August 2021 were retrospectively analyzed. The preoperative 18F-FDG PET/CT and chest enhanced CT-3D and other imaging data were extracted. The parameters with diagnostic significance were screened by the area under the receiver operating characteristic (ROC) curve (AUC). Three prediction models, including PET/CT prediction model (MOD PET), CT-3D prediction model (MOD CT-3D), and PET/CT combined CT-3D prediction model (MOD combination), were established through binary logistic regression, and the diagnostic performance of the models were validated by ROC curve. Results A total of 125 patients were enrolled, including 57 males and 68 females, with an average age of 61.16±8.57 years. There were 46 patients with benign nodules, and 79 patients with malignant nodules. A total of 2 PET/CT parameters and 5 CT-3D parameters were extracted. Two PET/CT parameters, SUVmax≥1.5 (AUC=0.688) and abnormal uptake of hilar/mediastinal lymph node metabolism (AUC=0.671), were included in the regression model. Among the CT-3D parameters, CT value histogram peaks (AUC=0.694) and CT-3D morphology (AUC=0.652) were included in the regression model. Finally, the AUC of the MOD PET was verified to be 0.738 [95%CI (0.651, 0.824)], the sensitivity was 74.7%, and the specificity was 60.9%; the AUC of the MOD CT-3D was 0.762 [95%CI (0.677, 0.848)], the sensitivity was 51.9%, and the specificity was 87.0%; the AUC of the MOD combination was 0.857 [95%CI (0.789, 0.925)], the sensitivity was 77.2%, the specificity was 82.6%, and the differences were statistically significant (P<0.001). Conclusion 18F-FDG PET/CT combined with CT-3D can improve the diagnostic performance of pulmonary nodules, and its specificity and sensitivity are better than those of single imaging diagnosis method. The combined prediction model is of great significance for the selection of surgical timing and surgical methods for pulmonary nodules, and provides a theoretical basis for the application of artificial intelligence in the pulmonary nodule diagnosis.
Prostate cancer is the most common tumor of the urinary system, and its mortality rate is second only to lung cancer. With the specific and high expression on the surface of prostate cancer cells, prostate-specific membrane antigen (PSMA) has been an ideal theranostic target of prostate cancer with great clinical significance and research value. Positron emission tomography/computed tomography (PET/CT), a new modality of molecular imaging combining functional metabolic information and anatomical structure, provides high diagnostic performance for cancer detection. This paper mainly reviewed recent progress of PSMA inhibitors labeled by positron-emitting radionuclides for early diagnosis, preoperative staging, response assessment, restaging and metastasis detection of prostate cancer.
Primary hepatocellular carcinoma is a common cancer. Many patients are found with intermediate-advanced stage, rapid development, poor treatment and high mortality. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) can discover the early lesions and therefore plays an important role in diagnosis, treatment and prognosis of patients with hepatocellular carcinoma. It especially has obvious advantages in detecting metastasis and monitoring recurrence. However, 18F-FDG PET/CT imaging has poor quality and low diagnosis rate. Understanding the advantages and limitations of 18F-FDG PET/CT can provide better basis for clinical diagnosis and treatment for hepatocellular carcinoma patients. This article briefly introduces the research and application of 18F-FDG PET/CT in the diagnosis and treatment of hepatocellular carcinoma.
The convolutional neural network (CNN) could be used on computer-aided diagnosis of lung tumor with positron emission tomography (PET)/computed tomography (CT), which can provide accurate quantitative analysis to compensate for visual inertia and defects in gray-scale sensitivity, and help doctors diagnose accurately. Firstly, parameter migration method is used to build three CNNs (CT-CNN, PET-CNN, and PET/CT-CNN) for lung tumor recognition in CT, PET, and PET/CT image, respectively. Then, we aimed at CT-CNN to obtain the appropriate model parameters for CNN training through analysis the influence of model parameters such as epochs, batchsize and image scale on recognition rate and training time. Finally, three single CNNs are used to construct ensemble CNN, and then lung tumor PET/CT recognition was completed through relative majority vote method and the performance between ensemble CNN and single CNN was compared. The experiment results show that the ensemble CNN is better than single CNN on computer-aided diagnosis of lung tumor.
The aim of this study is to analyze the concordance between EDV, ESV and LVEF values derived from 18F-FDG PET, GSPECT and ECHO in patients with myocardial infarction. Sixty-four patients with coronary artery disease (CAD) and myocardial infarction were enrolled in the study.. Each patient underwent at least two of the above mentioned studies within 2 weeks. LVEF、 EDV and ESV values were analyzed with dedicated software. Statistical evaluation of correlation and agreement was carried out EDV was overestimated by 18F-FDG PET compared with GSPECT [(137.98±61.71) mL and (125.35±59.34) mL]; ESV was overestimated by 18F-FDG PET (85.89±55.21) mL and GSPECT (82.39±55.56) mL compared with ECHO (68.22±41.37) mL; EF was overestimated by 18F-FDG PET (41.96%±15.08%) and ECHO (52.18%±13.87%) compared with GSPECT (39.75%±15.64%), and EF was also overestimated by 18F-FDG PET compared with GSPECT. The results of linear regression analysis showed good correlation between EDV, ESV and LVEF values derived from 18F-FDG PET, GSPECT and ECHO (r=0.643-0.873, P=0.000). Bland-Altman analysis indicated that 18F-FDG PET correlated well with ECHO in the Left ventricular function parameters. While GSPECT correlated well with 18F-FDG PET in ESV, GSPECT had good correlation with Echo in respect of EDV and EF; whereas GSPECT had poor correlation with PET/ECHO in the remaining left ventricular function parameters. Therefore, the clinical physicians should decide whether they would use the method according to the patients' situation and diagnostic requirements.
There are various examination methods for cardiovascular diseases. Non-invasive diagnosis and prognostic information acquisition are the current research hotspots of related imaging examinations. Positron emission tomography (PET)/magnetic resonance imaging (MRI) is a new advanced fusion imaging technology that combines the molecular imaging of PET with the soft tissue contrast function of MRI to achieve their complementary advantages. This article briefly introduces several major aspects of cardiac PET/MRI in the diagnosis of cardiovascular disease, including atherosclerosis, ischemic cardiomyopathy, nodular heart disease, and myocardial amyloidosis, in order to promote cardiac PET/MRI to be more widely used in precision medicine in this field.
The widespread use of low-dose computed tomography (LDCT) in lung cancer screening has enabled more and more lung nodules to get identified of which more than 20% are multiple pulmonary nodules. At present, there is no guideline or consensus for multiple pulmonary nodules whose management is based primarily on the pulmonary imaging characteristics and associated risk factors. Herein, this review covers the imaging methods, CT appearances and management of multiple pulmonary nodules.