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Objective:To improve the quality of 18F-fluorodeoxyglucose (FDG) PET images at different acquisition times through deep learning (DL) PET image reconstruction methods. Methods:A total of 45 patients (20 males, 25 females; age (52.0±13.6) years) with malignant tumors and PET/CT scans from September 2020 to October 2020 in the Department of Nuclear Medicine of the First Hospital of Shanxi Medical University were included in this retrospective study. The short acquisition time 30 s/bed PET images from the raw list mode were selected as the input of DL model. DL image reconstruction model, based on the Unet algorithm, was trained to output imitated PET images with full dose standard acquisition time (3 min). The image quality evaluation and quantitative analysis were carried out for four groups of images: DL images, 30 s, 90 s, and 120 s images, respectively. The quality of PET images in four groups was evaluated using the five-point method. Liver background activities, lesions quantification parameters (maximum standardized uptake value (SUV max), mean standardized uptake value (SUV mean), standard deviation (SD), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR)), and first-order texture features (skewness, kurtosis, uniformity, entropy) were measured. Kappa test, χ2 test and one-way analysis of variance (least significant difference t test) were used for data analysis. Results:The image quality scores between four groups were highly consistent ( Kappa=0.799, P<0.001). The number of patients with scores≥3 in DL, 30 s, 90 s and 120 s groups were 6, 4, 7 and 8, respectively ( χ2=125.47, P<0.001). The liver SD of DL group was significantly lower than that of 30 s group (0.26±0.07 vs 0.43±0.11; F=3.58, t=-7.91, P<0.05). The liver SNR of DL group was higher than that of 30 s group (11.04±4.36 vs 5.41±1.41; F=10.22, t=5.40, P<0.05). The liver SD and SNR of DL group were similar to those of 90 s group (0.39±0.16, 8.46±3.34; t values: -0.87 and 2.17, both P>0.05). In 18 tumor lesions with high uptake, SNR and CNR of DL group were significantly higher than those of 30 s group (60.21±29.26 vs 38.38±16.54, 22.26±15.85 vs 15.41±9.51; F values: 13.09 and 7.05; t values: 5.20 and 4.04, both P<0.001). There were statistically significant differences among four groups in the first-order texture features ( F values: 4.30-9.65, all P<0.05), but there was no significant difference between DL group and 120 s group ( t values: from -1.25 to 0.15, all P>0.05). Conclusion:DL reconstruction model can improve the quality of short-frame PET images, which meets the needs of clinical diagnosis, efficacy evaluation and radiomics research.
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Objective@#To investigate the value of 18F-fluorodeoxyglucose (FDG) PET/CT imaging and cardiac MRI (CMR) in the diagnosis of radiation-induced heart disease (RIHD) in Beagle models.@*Methods@#Twenty-four normal male Beagle dogs (1-year old) were randomly divided into control group and irradiated groups (3-month, 6-month and 12-month after radiation). The left anterior myocardium of Beagle dogs in irradiated groups was irradiated locally with a single dose of 20 Gy X-ray. Cardiac 18F-FDG PET/CT imaging and CMR were performed on all dogs, and the mean standardized uptake value (SUVmean) and the area of lesions with increased 18F-FDG uptake were obtained. After imaging examinations were finished, dogs were sacrificed and their hearts were taken out to perform Masson staining and electron microcopy. One-way analysis of variance was used for data analysis.@*Results@#There was basically no uptake in myocardium in control group. The myocardium showed increased uptake of 18F-FDG in the irradiated groups. The SUVmean of myocardium in 3-month, 6-month and 12-month after radiation groups and control group were 5.90±1.31, 4.66±2.21, 3.21±0.82 and 1.13±0.21, respectively (F=11.81, P<0.05). The area with increased 18F-FDG uptake in the irradiated groups decreased progressively with the prolongation of irradiation time (F=195.74, P<0.01). The reduction in myocardial perfusion and myocardial fibrosis were observed by CMR early at 6-month after irradiation. Compared with the control group, the 6-month and 12-month after radiation groups had increased end diastolic volume (EDV) and end systolic volume (ESV; F=15.479 and 16.908, both P<0.01), and decreased left ventricular ejection fraction (LVEF; F=63.715, P<0.01). The progressive aggravation of myocardial fibrosis was displayed in irradiated groups by Masson staining. The mitochondria degeneration, swelling and the count reduction in irradiated groups were observed by electron microscopy.@*Conclusions@#The increased 18F-FDG uptake in the irradiated myocardium may predict the risk of RIHD. 18F-FDG PET/CT imaging can detect RIHD earlier than CMR.
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Objective:To analyze variant patterns and characteristics of focal physiological uptake (FPU) in the tongue on 18F-fluorodeoxyglucose (FDG) PET/CT imaging in patients without a history of oral tumor surgery and radiotherapy. Methods:A total of 6 233 consecutive patients who underwent routine whole-body PET/CT scan between January 2013 and December 2017 in the First Hospital of Shanxi Medical University were investigated retrospectively, and 324 patients with a history of oral surgery and radiotherapy were excluded, the remaining 5 909 patients (3 418 males, 2 491 females, age range: 2-95 (average: 58) years) were enrolled. A part of the patients underwent local PET/CT scan and CT scan with diagnostic dose, covering the oral cavity on mouth-opening position. The morphological characteristics of FPU patterns were analyzed, and the maximum standardized uptake value (SUV max) was measured. Results:Seventy-six FPUs in 76 patients (49 males, 27 females, age range: 40-83 (average 64) years) identified by routine whole-body PET/CT scan were confirmed by clinical examination from a specialist in stomatology or follow-up for more than 6 months. Forty-one of the 76 patients subsequently underwent local PET/CT scan and diagnostic CT scan on mouth-opening position. The incidence of FPU in the tongue was 1.29%(76/5 909). The FPU patterns could be classified into three types: type Ⅰ with FDG uptake involved only anterior part of the tongue body in the midline (near the tip of the tongue), which showed as a " dotted" shape( n=68; 1.15%, 68/5 909); type Ⅱ with FDG uptake involved mainly middle part of the genioglossus muscle, which showed as a " bar-shorted" shape ( n=5; 0.08%, 5/5 909); type Ⅲ with FDG uptake involved large part of the tongue body and the genioglossus, which showed as a " T" shape( n=3; 0.05%, 3/5 909). The SUV max in patients with type Ⅰ and type Ⅱ were 5.53(4.53, 7.30), 19.50(17.10, 22.74) respectively. The SUV max in 3 patients with type Ⅲ were 23.34, 27.50 and 35.14, respectively. Conclusion:In patients without a history of oral tumor surgery and radiotherapy, the FPU in the tongue has its specific pattern, and PET/CT scan on mouth-opening position helps to reveal the detailed features.
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Objective:To compare four reconstruction algorithms of 18F-fluorodeoxyglucose (FDG) PET/CT on standardized uptake value (SUV) of pulmonary nodules. Methods:A total of 46 patients (27 males, 19 females; median age: 66 (range: 44-82) years) with solid pulmonary nodules from February 2018 to July 2019 in the First Hospital of Shanxi Medical University who performed 18F-FDG PET/CT imaging were enrolled. All PET/CT images were retrospectively reconstructed by using four algorithms reconstructions including ordered subset expectation maximization (OSEM), OSEM+ time of flight (TOF), OSEM+ TOF+ point spread function (PSF) and block sequential regularized expectation maximization (BSREM) (G1-G4). Nodule and background parameters were analyzed semi-quantitatively and visually. The maximum of SUV(SUV max), mean of SUV(SUV mean) and peak of SUV (SUV peak) were collected by the region of interest (ROI). Nodules were divided into small nodule group (diameter ≤10 mm) and large nodule group (10 mm < diameter ≤30 mm). Kruskal-Wallis rank sum test and Bonferroni method were performed to compare the differences of SUVs between G1-G4, and Spearman correlation analysis was used to analyze the correlation between the change rate of SUV (%ΔSUV) and the diameter of nodules. The receiver operating characteristic (ROC) curve analysis was used to analyze the diagnostic efficacy of SUV for the differential diagnosis of pulmonary nodules and to get the optimal threshold. Results:There were 114 pulmonary nodules (large nodules, n=55; small nodules, n=59). In visual analysis, the visual detection rates of small nodules in G4 were 55.93%(33/59), 44.07%(26/59), 20.34%(12/59) higher than those in G1-G3. Of 114 pulmonary nodules in 46 patients, there were differences in SUV max and SUV mean between G1-G4 (median SUV max : 2.65-5.29, median SUV mean: 2.05-2.99; H values: 20.628 and 17.749, respectively, both P<0.001), G4 had significant increases compared to G1 in SUV max (median 5.29 and 2.65, P<0.001) and SUV mean (median 2.99 and 2.05, P<0.001). The %ΔSUV max (median: 4.45%-52.96%) and %ΔSUV mean (median: 1.69%-47.56%) were negatively correlated with the diameter of nodules (9.75(6.20, 16.58) mm; r s values: -0.371 to -0.354, -0.371 to -0.320, all P<0.001). In 59 small nodules, G1 significantly increased the SUV max of G4 (median 4.05 and 2.14, H=18.327, P<0.001), while G4 significantly increased the SUV mean of G1 and G3 (median 2.31, 1.26 and 1.53, H=16.808, P<0.05). There was no significant difference in SUVs between G1-G4 in 55 large nodules ( H values: 0.812-7.290, all P>0.05). The optimal threshold values of SUV max in G1-G4 were 4.335, 5.185, 5.410, 5.745 and the area of under curves (AUCs) were 0.747, 0.699, 0.756, 0.778 respectively. The AUC of SUV mean and SUV peak also showed a similar trend. Conclusion:Among the four reconstruction algorithms, BRERM can not only enhance the image quality, but also significantly improve the SUV max and SUV mean of lung nodules diameter below 10 mm, and thus its diagnostic threshold of SUV should be appropriately increased.
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Objective To investigate the value of 18F-fluorodeoxyglucose (FDG) PET/CT imaging and cardiac MRI (CMR) in the diagnosis of radiation-induced heart disease (RIHD) in Beagle models.Methods Twenty-four normal male Beagle dogs (1-year old) were randomly divided into control group and irradiated groups (3-month,6-month and 12-month after radiation).The left anterior myocardium of Beagle dogs in irradiated groups was irradiated locally with a single dose of 20 Gy X-ray.Cardiac 18F-FDG PET/CT imaging and CMR were performed on all dogs,and the mean standardized uptake value (SUVmax) and the area of lesions with increased 18F-FDG uptake were obtained.After imaging examinations were finished,dogs were sacrificed and their hearts were taken out to perform Masson staining and electron microcopy.Oneway analysis of variance was used for data analysis.Results There was basically no uptake in myocardium in control group.The myocardium showed increased uptake of 18F-FDG in the irradiated groups.The SUV of myocardium in 3-month,6-month and 12-month after radiation groups and control group were 5.90± 1.31,4.66±2.21,3.21±0.82 and 1.13±0.21,respectively (F=11.81,P＜0.05).The area with increased 18F-FDG uptake in the irradiated groups decreased progressively with the prolongation of irradiation time (F =195.74,P＜0.01).The reduction in myocardial perfusion and myocardial fibrosis were observed by CMR early at 6-month after irradiation.Compared with the control group,the 6-month and 12-month after radiation groups had increased end diastolic volume (EDV) and end systolic volume (ESV;F =15.479 and 16.908,both P＜0.01),and decreased left ventricular ejection fraction (LVEF;F=63.715,P＜0.01).The progressive aggravation of myocardial fibrosis was displayed in irradiated groups by Masson staining.The mitochondria degeneration,swelling and the count reduction in irradiated groups were observed by electron microscopy.Conclusions The increased 18F-FDG uptake in the irradiated myocardium may predict the risk of RIHD.18F-FDG PET/CT imaging can detect RIHD earlier than CMR.
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Objective To establish radiation-induced heart disease ( RIHD) Beagle models, in-vestigate the efficacy of 18 F-FDG PET/CT in the detection of RIHD and observe the pathological changes. Methods The ventricular anterior wall of 12 Beagle dogs were X-ray irradiated locally with a single dose of 20 Gy. 18 F-FDG PET/CT and echocardiography were performed at baseline and 3 months after radiation. ROI was drawn on the irradiation field and the non-irradiation field ( the posterior wall of left ventricle) to obtain the SUVmax . Then the SUVmax ratio of the irradiation field to the non-irradiation field ( INR) was cal-culated. The left ventricular function parameters before and after radiation were obtained by echocardio-graphy. Within 1 week after the imaging examinations were finished, the dogs were sacrificed, and hearts were taken out to perform pathological observation. Paired t test was used to analyze the data. Results High 18 F-FDG uptake in the irradiation field was shown 3 months after radiation. The average INRs before and after radiation were 0.99±0.15 and 2.54±0.43 respectively (t=7.021, P=0.001). No significant difference was ob-served on cardiac function parameters between baseline and 3 months after radiation( t values:from-1.253 to-0.786, all P>0.05) . The pathological results showed a few degenerated myocytes, increased thickness of myocardial vascular walls in irradiated myocardium. Conclusions 18 F-FDG PET/CT can detect early RIHD before abnormal cardiac function. Increased 18 F-FDG uptake in irradiated field may be related to myocardial ischemia which results from microvascular damage by radiation.
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Objective@#To explore the diagnostic efficacy of by 18F-FDG PET-CT for hypermetabolic thyroid nodules.@*Methods@#To retrospectively analyze the clinical data of 3 192 patients underwent 18F-FDG PET-CT in our hospital from May 2012 to October 2014. Among them, 98 patients were diagnosed with focal hypermetabolic thyroid nodules. 61 of the 98 patients were diagnosed with malignant or benign thyroid nodules using histopathological or clinical follow-up (22 malignant nodules, 39 benign nodules). The average age of these 61 patients was 61.6±12.5 years.@*Results@#The lgSUVmax of malignant group (0.69±0.31) was significantly higher than that in benign group (0.43±0.27) (P=0.001). There was no significant difference in age, gender, nodule size, minimum diameter of nodule, lgCT, calcification, the boundary definition, density uniformity, and history of malignancy between the two groups (P>0.05). Binary Logistic regression indicated the AUC of Logistic regressive model(AUC) was 0.866±0.049 (95% CI: 0.769-0.963), and the malignant AUCs of ROC curve was 0.747±0.068 (95%CI: 0.614-0.880) which was only determined by lgSUVmax. The difference was statistically significant (P<0.01).@*Conclusion@#18F-FDG PET-CT imaging can not only detect hypermetabolic thyroid nodules, but also have a certain clinical value for the identification of benign and malignant nodules.
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OBJECTIVE: To determine the efficacy of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in the detection of radiation-induced myocardial damage in beagles by comparing two pre-scan preparation protocols as well as to determine the correlation between abnormal myocardial FDG uptake and pathological findings. MATERIALS AND METHODS: The anterior myocardium of 12 beagles received radiotherapy locally with a single X-ray dose of 20 Gy. 18F-FDG cardiac PET/CT was performed at baseline and 3 months after radiation. Twelve beagles underwent two protocols before PET/CT: 12 hours of fasting (12H-F), 12H-F followed by a high-fat diet (F-HFD). Regions of interest were drawn on the irradiation and the non-irradiation fields to obtain their maximal standardized uptake values (SUVmax). Then the ratio of the SUV of the irradiation to the non-irradiation fields (INR) was computed. Histopathological changes were identified by light and electron microscopy. RESULTS: Using the 12H-F protocol, the average INRs were 1.18 +/- 0.10 and 1.41 +/- 0.18 before and after irradiation, respectively (p = 0.021). Using the F-HFD protocol, the average INRs were 0.99 +/- 0.15 and 2.54 +/- 0.43, respectively (p < 0.001). High FDG uptake in irradiation field was detected in 33.3% (4/12) of 12H-F protocol and 83.3% (10/12) of F-HFD protocol in visual analysis, respectively (p = 0.031). The pathology of the irradiated myocardium showed obvious perivascular fibrosis and changes in mitochondrial vacuoles. CONCLUSION: High FDG uptake in an irradiated field may be related with radiation-induced myocardial damage resulting from microvascular damage and mitochondrial injury. An F-HFD preparation protocol used before obtaining PET/CT can improve the sensitivity of the detection of cardiotoxicity associated with radiotherapy.