Objective:To investigate the application of 18F-FDG PET/MR and its derived parameters in the diagnosis and staging of bladder cancer. Methods:Forty patients (32 males, 8 females; age (66.8±11.2) years) with suspected bladder cancer between December 2019 and March 2022 were retrospectively included and underwent 18F-FDG PET/MR in Nanjing First Hospital. Parameters including SUV max, SUV mean, maximum tumor diameter and mean of apparent diffusion coefficient (ADC mean) were obtained, and bladder cancer muscle invasiveness and lymph node involvement were determined. The efficacy of 18F-FDG PET/MR and its derived parameters for tumor diagnosis and staging was analyzed using transurethral resection of bladder tumor (TUR-BT) or radical cystectomy (RC) and extended pelvic lymph node dissection (ePLND) histopathology as the " gold standard". Independent-sample t test, Mann-Whitney U test or χ2 test was used to analyze the data, and Delong test was used to compare different AUCs. Results:Of 40 patients, 8 were non-muscle invasive bladder cancer (NMIBC), 32 were muscle invasive bladder cancer (MIBC), and 5 were pathologically confirmed to have lymph node metastasis. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 18F-FDG PET/MR for identifying MIBC were 96.9%(31/32), 7/8, 96.9%(31/32), 7/8, 95.0%(38/40), respectively, and those for lymph node metastasis were 4/5, 90.0%(18/20), 4/6, 18/19, 88.0%(22/25), respectively. For pathological tumor (pT) staging, significant differences were observed between pT2-3 and pT1 groups in maximum tumor diameter ( t=-2.37, P=0.024), SUV mean( Z=-2.11, P=0.035), and ADC mean( t=2.91, P=0.006). The AUCs of maximum tumor diameter, SUV mean and ADC mean in distinguishing MIBC were 0.781, 0.746, and 0.825, respectively. The sensitivity, specificity, PPV, NPV, and accuracy of MRI alone in identifying MIBC were 87.5%(28/32), 1/8, 80.0%(28/35), 1/5 and 72.5%(29/40), respectively, with the AUC of 0.500. The AUC of 18F-FDG PET/MR in identifying MIBC was 0.796, which was better than MRI alone ( Z=5.54, P<0.001), and the accuracy of PET/MR was also higher than MRI alone ( χ2=7.44, P=0.006). Conclusion:Compared with MRI alone, 18F-FDG PET/MR significantly improves the diagnostic efficacy of bladder cancer and the accuracy of pT staging.

Objective:To investigate the enhancement effect of deep progressive reconstruction (DPR) algorithm on image quality and standardized uptake value (SUV) of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in obese patients. Methods:The images of a total of 27 obese patients,who underwent 18F-FDG PET/CT in Affiliated Nanjing Hospital of Nanjing Medical University from September 2023 to May 2024,were retrospectively enrolled. The images of all patients were collected by using uMI 780 PET/CT. Ordered subset expectation maximization (OSEM) iterative algorithm and DPR algorithm were adopted to reconstruct PET images,and measure counting rate of scattering coincidence of PET/CT images,counting rate of true coincidence,noise equivalent counting rate (NECR) and scattering fraction (SF). The quality indicators of PET images included signal-to-noise ratio (SNR),the maximum SUV (SUVmax) of lesions,the tumor-to-background ratio (TBR),the contrast-to-noise ratio (CNR) and the visual scores of 18F-FDG PET/CT images on livers were evaluated. The differences and consistency of various indicators between DPR and OSEM reconstruction algorithms were further analyzed. Results:The average 18F-FDG PET/CT injection activity of 27 patients was (0.12±0.01) mCi (1 mCi=37 MBq)/kg,and the counting rate of true coincidence,NECR and SF of PET images were respectively (153.73±25.09),(44.81±8.47) kcps and (36.77±1.91)％. The SNR of liver obtained by DPR algorithm was (15.83±3.60),which was significantly higher than that (9.06±1.87) of OSEM algorithm,with statistically significant (t=20.6,P<0.05),and there was significantly correlation in liver SNR between two algorithms (R2=0.91,P<0.05). In 27 uptake 18F-FDG PET/CT lesions,the SUVmax,TBR and CNR of lesions that were obtained from OSEM algorithm were respectively (5.86±1.49),(1.95±0.49) and (17.74±4.77),which were lower than corresponding those of DPR algorithm,and the differences were significant (t=9.03,8.79,15.49,P<0.05),respectively. There were significant correlations in SUVmax,TBR and CNR between the two algorithms (R2=0.71,0.70,0.76,P<0.05),respectively. The visual scores of PET images obtained from the DPR algorithm was 4 (3,5) scores,which was significantly higher than 3 (2,4) scores of OSEM algorithm,and the difference of that between two algorithms was significant (U=396,P<0.05). Conclusion:The scattering effect of 18F-FDG PET/CT imaging is stronger in obese patients,whose counting rate of equivalent effect of noise is lower. The DPR reconstruction algorithm can significantly improve the SNR and lesion contrast of PET images than the OSEM algorithm,which has significant gain effect on the SUVmax of lesions,and it can significantly improve the quality of 18F-FDG PET/PET images in obese patients.

Objective To observe the effect of automatic segmentation of prostate cancer(PCa)in 68Ga-prostate specific membrane antigen(PSMA)-11 PET/MRI based on diffusion models.Methods A dataset contained 68Ga-PSMA-11 PET/MRI of 125 cases of PCa was preprocessed.Segmentation network was designed based on Faster-RCNN and spatial and channel reconstruction convolution(SCConv)Diffusion cascade,in which the first-level was used to coarsely localize the prostate and seminal vesicle glands using Faster-RCNN,and the second-level SCConv Diffusion network based on diffusion model was used to segment PCa.The effect of the above models for segmenting PCa in 68Ga-PSMA-11 PET/MRI were observed.Results The Dice similarity coefficient(DSC),intersection over union(IoU),and 95％Hausdorff distance(HD)of the Faster-RCNN+SCConv Diffusion model for segmenting PCa in 68Ga-PSMA-11 PET/MRI was 0.76,0.63 and 20.02 mm,all superior to those of nnU-Net(0.73,0.62 and 21.20 mm)and Faster-RCNN+nnU-Net(0.75,0.62 and 20.70 mm)models,and the segmentation for both single and multiple PCa were all accurate,with less missegment non-tumor tissue.Conclusion Diffusion model based on Faster-RCNN+SCConv diffusion cascade network could be used to completely and accurately segment PCa in 68Ga-PSMA-11 PET/MRI.

Objective:To investigate the enhancement effect of deep progressive reconstruction (DPR) algorithm on image quality and standardized uptake value (SUV) of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in obese patients. Methods:The images of a total of 27 obese patients,who underwent 18F-FDG PET/CT in Affiliated Nanjing Hospital of Nanjing Medical University from September 2023 to May 2024,were retrospectively enrolled. The images of all patients were collected by using uMI 780 PET/CT. Ordered subset expectation maximization (OSEM) iterative algorithm and DPR algorithm were adopted to reconstruct PET images,and measure counting rate of scattering coincidence of PET/CT images,counting rate of true coincidence,noise equivalent counting rate (NECR) and scattering fraction (SF). The quality indicators of PET images included signal-to-noise ratio (SNR),the maximum SUV (SUVmax) of lesions,the tumor-to-background ratio (TBR),the contrast-to-noise ratio (CNR) and the visual scores of 18F-FDG PET/CT images on livers were evaluated. The differences and consistency of various indicators between DPR and OSEM reconstruction algorithms were further analyzed. Results:The average 18F-FDG PET/CT injection activity of 27 patients was (0.12±0.01) mCi (1 mCi=37 MBq)/kg,and the counting rate of true coincidence,NECR and SF of PET images were respectively (153.73±25.09),(44.81±8.47) kcps and (36.77±1.91)％. The SNR of liver obtained by DPR algorithm was (15.83±3.60),which was significantly higher than that (9.06±1.87) of OSEM algorithm,with statistically significant (t=20.6,P<0.05),and there was significantly correlation in liver SNR between two algorithms (R2=0.91,P<0.05). In 27 uptake 18F-FDG PET/CT lesions,the SUVmax,TBR and CNR of lesions that were obtained from OSEM algorithm were respectively (5.86±1.49),(1.95±0.49) and (17.74±4.77),which were lower than corresponding those of DPR algorithm,and the differences were significant (t=9.03,8.79,15.49,P<0.05),respectively. There were significant correlations in SUVmax,TBR and CNR between the two algorithms (R2=0.71,0.70,0.76,P<0.05),respectively. The visual scores of PET images obtained from the DPR algorithm was 4 (3,5) scores,which was significantly higher than 3 (2,4) scores of OSEM algorithm,and the difference of that between two algorithms was significant (U=396,P<0.05). Conclusion:The scattering effect of 18F-FDG PET/CT imaging is stronger in obese patients,whose counting rate of equivalent effect of noise is lower. The DPR reconstruction algorithm can significantly improve the SNR and lesion contrast of PET images than the OSEM algorithm,which has significant gain effect on the SUVmax of lesions,and it can significantly improve the quality of 18F-FDG PET/PET images in obese patients.

Objective To observe the effect of automatic segmentation of prostate cancer(PCa)in 68Ga-prostate specific membrane antigen(PSMA)-11 PET/MRI based on diffusion models.Methods A dataset contained 68Ga-PSMA-11 PET/MRI of 125 cases of PCa was preprocessed.Segmentation network was designed based on Faster-RCNN and spatial and channel reconstruction convolution(SCConv)Diffusion cascade,in which the first-level was used to coarsely localize the prostate and seminal vesicle glands using Faster-RCNN,and the second-level SCConv Diffusion network based on diffusion model was used to segment PCa.The effect of the above models for segmenting PCa in 68Ga-PSMA-11 PET/MRI were observed.Results The Dice similarity coefficient(DSC),intersection over union(IoU),and 95％Hausdorff distance(HD)of the Faster-RCNN+SCConv Diffusion model for segmenting PCa in 68Ga-PSMA-11 PET/MRI was 0.76,0.63 and 20.02 mm,all superior to those of nnU-Net(0.73,0.62 and 21.20 mm)and Faster-RCNN+nnU-Net(0.75,0.62 and 20.70 mm)models,and the segmentation for both single and multiple PCa were all accurate,with less missegment non-tumor tissue.Conclusion Diffusion model based on Faster-RCNN+SCConv diffusion cascade network could be used to completely and accurately segment PCa in 68Ga-PSMA-11 PET/MRI.

Objective:To investigate the application of 18F-FDG PET/MR and its derived parameters in the diagnosis and staging of bladder cancer. Methods:Forty patients (32 males, 8 females; age (66.8±11.2) years) with suspected bladder cancer between December 2019 and March 2022 were retrospectively included and underwent 18F-FDG PET/MR in Nanjing First Hospital. Parameters including SUV max, SUV mean, maximum tumor diameter and mean of apparent diffusion coefficient (ADC mean) were obtained, and bladder cancer muscle invasiveness and lymph node involvement were determined. The efficacy of 18F-FDG PET/MR and its derived parameters for tumor diagnosis and staging was analyzed using transurethral resection of bladder tumor (TUR-BT) or radical cystectomy (RC) and extended pelvic lymph node dissection (ePLND) histopathology as the " gold standard". Independent-sample t test, Mann-Whitney U test or χ2 test was used to analyze the data, and Delong test was used to compare different AUCs. Results:Of 40 patients, 8 were non-muscle invasive bladder cancer (NMIBC), 32 were muscle invasive bladder cancer (MIBC), and 5 were pathologically confirmed to have lymph node metastasis. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of 18F-FDG PET/MR for identifying MIBC were 96.9%(31/32), 7/8, 96.9%(31/32), 7/8, 95.0%(38/40), respectively, and those for lymph node metastasis were 4/5, 90.0%(18/20), 4/6, 18/19, 88.0%(22/25), respectively. For pathological tumor (pT) staging, significant differences were observed between pT2-3 and pT1 groups in maximum tumor diameter ( t=-2.37, P=0.024), SUV mean( Z=-2.11, P=0.035), and ADC mean( t=2.91, P=0.006). The AUCs of maximum tumor diameter, SUV mean and ADC mean in distinguishing MIBC were 0.781, 0.746, and 0.825, respectively. The sensitivity, specificity, PPV, NPV, and accuracy of MRI alone in identifying MIBC were 87.5%(28/32), 1/8, 80.0%(28/35), 1/5 and 72.5%(29/40), respectively, with the AUC of 0.500. The AUC of 18F-FDG PET/MR in identifying MIBC was 0.796, which was better than MRI alone ( Z=5.54, P<0.001), and the accuracy of PET/MR was also higher than MRI alone ( χ2=7.44, P=0.006). Conclusion:Compared with MRI alone, 18F-FDG PET/MR significantly improves the diagnostic efficacy of bladder cancer and the accuracy of pT staging.

Objective:To explore the diagnostic value of 68Ga-prostate specific membrane antigen (PSMA)-11 PET/MR multiparameter multimodal functional imaging in the diagnosis of naive prostate cancer (PCa), and to analyze its efficacy in the early stages of PCa. Methods:From July to September 2019, 45 suspected or pathologically confirmed PCa patients (average age: 69 years) who met the inclusion criteria were collected to perform 68Ga-PSMA-11 PET/MR examination in Nanjing First Hospital. After the scanning was completed, the method of region of interest (ROI) was used to semi-quantitatively calculate the tumor radioactive uptake in the fusion image, including the maximum standardized uptake value (SUV max), tumor metabolic volume (MTV) and mean standardized uptake value (SUV mean), and PSMA expression load was calculated(SUV mean×MTV). Apparent diffusion coefficient (ADC) values of ROI were measured in ADC images ( b=1 500 s/mm 2). The efficacy of 68Ga-PSMA-11 PET/MR in the preoperative diagnosis of PCa and the effect on clinical staging were evaluated with the pathological results. The correlation between prostate specific antigen (PSA) and radiation uptake in PCa tissues, PSMA expression load and ADC values was analyzed by Pearson correlation. Independent-sample t test was used to analyze the data. Results:Pathologically, 38 of the 45 patients were with PCa and 7 patients had benign prostatic hypertrophy (BPH), and metastasis occurred in 12 of the 38 PCa patients. 68Ga-PSMA-11 PET/MR detected 39 cases of PCa with one of which was false-positive. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 68Ga-PSMA-11 PET/MR were 100%(38/38), 6/7, 97.4%(38/39), 6/6 and 97.8%(44/45), respectively. The tumor tissues of PCa often showed focal radioactive uptake, and the T 2 weighted imaging (WI) showed focal low signal and limited dispersion. BPH showed slightly uneven uptake, and T 2WI and diffusion weighted imaging (DWI) showed uneven diffuse signals. SUV max of PCa was significantly higher than that of BPH (24.66±19.21 vs 4.97±2.13; t=5.208, P<0.001). ADC values of PCa were significantly lower than that of BPH ((0.91±0.37)×10 -3vs (1.08±0.24)×10 -3 mm/s 2; t=2.816, P<0.05). SUV max and the expression loads of PSMA in PCa were positively correlated with PSA ( r values: 0.42 and 0.71, both P<0.05). ADC values of tumor tissues in PCa were negatively correlated with PSA ( r=-0.37, P=0.013). Conclusion:68Ga-PSMA-11 PET/MR has great merits in the early diagnosis and staging of PCa.