Automatic Lung Cancer Segmentation in 18 FFDG PET/CT Using a Two-Stage Deep Learning Approach / 대한핵의학회잡지

Purpose@#Since accurate lung cancer segmentation is required to determine the functional volume of a tumor in [ 18 F]FDG PET/CT, we propose a two-stage U-Net architecture to enhance the performance of lung cancer segmentation using [ 18 F]FDG PET/CT. @*Methods@#The whole-body [ 18 F]FDG PET/CT scan data of 887 patients with lung cancer were retrospectively used for network training and evaluation. The ground-truth tumor volume of interest was drawn using the LifeX software. The dataset was randomly partitioned into training, validation, and test sets. Among the 887 PET/CT and VOI datasets, 730 were used to train the proposed models, 81 were used as the validation set, and the remaining 76 were used to evaluate the model. In Stage 1, the global U-net receives 3D PET/CT volume as input and extracts the preliminary tumor area, generating a 3D binary volume as output. In Stage 2, the regional U-net receives eight consecutive PET/CT slices around the slice selected by the Global U-net in Stage 1 and generates a 2D binary image as the output. @*Results@#The proposed two-stage U-Net architecture outperformed the conventional one-stage 3D U-Net in primary lung cancer segmentation. The two-stage U-Net model successfully predicted the detailed margin of the tumors, which was determined by manually drawing spherical VOIs and applying an adaptive threshold. Quantitative analysis using the Dice similarity coefficient confirmed the advantages of the two-stage U-Net. @*Conclusion@#The proposed method will be useful for reducing the time and effort required for accurate lung cancer segmentation in [ 18 F]FDG PET/CT.

Recent Survey of Effective Doses of F-18 FDG Torso PET/CT in Korea and the Current Recommendations for CT Protocols of PET/CT / 대한핵의학회잡지

Purpose@#This study aimed to construct a database of the effective doses (ED) from F-18 fluorodeoxyglucose (FDG) torso positron emission tomography/computed tomography (PET/CT) in Korea to provide data that supports the reduction of the CT dose of PET/CT and optimization of PET/CT protocols in Korea. @*Methods@#We investigated data of ED and CT parameters of FDG PET/CT. The data were analyzed by body weight groups. @*Results@#A total of 31 hospitals participated in the survey (99 adults). The mean total EDs (± SD) were 8.77 ± 2.76, 10.93 ± 3.14, and 12.57 ± 3.79 mSv for the 55-, 70-, and 85-kg groups, respectively. The FDG EDs were 4.80 ± 0.98, 6.05 ± 1.15, and 6.89 ± 1.52 mSv, and the CT EDs were 4.00 ± 2.12, 4.88 ± 2.51, and 5.68 ± 2.89 mSv, respectively. Of the enrolled hospitals, 54.5% used ultra-low-dose CT protocols, and their CT ED was significantly lower than low-dose CT group in all groups (2.9 ± 1.0, 3.2 ± 1.1, and 3.3 ± 1.0 mSv vs. 6.6 ± 1.6, 7.2 ± 2.1, and 7.9 ± 2.2 mSv, all p < 0.001, respectively). In the ultra-low-dose CT group, the CT ED with the iterative reconstruction was significantly lower than that of CT without iterative reconstruction in the 55-kg group (2.4 ± 0.9 vs. 3.3 ± 0.9, p = 0.04). @*Conclusions@#These results and current recommendations can be helpful for optimizing PET/CT diagnostic reference level (DRL) and reducing unnecessary PET/CT radiation exposure.

Ratio of Mediastinal Lymph Node SUV to Primary Tumor SUV in ¹⁸F-FDG PET/CT for Nodal Staging in Non-Small-Cell Lung Cancer / 대한핵의학회잡지

PURPOSE: Following determination of the maximum standardized uptake values (SUVmax) of the mediastinal lymph nodes (SUV-LN) and of the primary tumor (SUV-T) on ¹⁸F-FDG PET/CT in patients with non-small-cell lung cancer (NSCLC), the aim of the study was to determine the value of the SUV-LN/SUV-T ratio in lymph node staging in comparison with that of SUV-LN.METHODS: We retrospectively reviewed a total of 289 mediastinal lymph node stations from 98 patients with NSCLC who were examined preoperatively for staging and subsequently underwent pathologic studies of the mediastinal lymph nodes. We determined SUV-LN and SUV-R for each lymph node station on ¹⁸F-FDG PET/CT and then classified each station into one of three groups based on SUV-T (low, medium and high SUV-T groups). Diagnostic performance was assessed based on receiver operating characteristic (ROC) curve analysis, and the optimal cut-off values that would best discriminate metastatic from benign lymph nodes were determined for each method.RESULTS: The average of SUV-R of malignant lymph nodes was significantly higher than that of benign lymph nodes (0.79±0.45 vs. 0.36±0.23, P<0.0001). In the ROC curve analysis, the area under the curve (AUC) of SUV-R was significantly higher than that of SUV-LN in the low SUV-T group (0.885 vs. 0.810, P= 0.019). There were no significant differences between the AUCs of SUV-LN and of SUV-R in the medium and high SUV-T groups. The optimal cut-off value for SUV-R in the low SUV-T group was 0.71 (sensitivity 87.5 %, specificity 85.9 %).CONCLUSIONS: The SUV-R performed well in distinguishing between metastatic and benign lymph nodes. In particular, SUV-R was found to have a better diagnostic performance than SUV-LN in the low SUV-T group.

The Role of 18F-Fluorodeoxyglucose Positron Emission Tomography as a Prognostic Indicator for Bile Duct and Gallbladder Cancer: Need for a Prospective Study Using Various Quantitative Parameters / 대한소화기학회지

No abstract available.

The Discriminating Nature of Dopamine Transporter Image in Parkinsonism: The Competency of Dopaminergic Transporter Imaging in Differential Diagnosis of Parkinsonism: 123I-FP-CIT SPECT Study / 핵의학분자영상

PURPOSE: The aim of this study was to evaluate the discriminating nature of 123I-FP-CIT SPECT in patients with parkinsonism. METHODS: 123I-FP-CIT SPECT images acquired from the 18 normal controls; NC (60.4+/-10.0 yr) and 237 patients with parkinsonism (65.9+/-9.2 yr) were analyzed. From spatially normalized images, regional counts of the caudate, putamen, and occipital lobe were obtained using region of interest method. Binding potential (BP) was calculated with the ratio of specific to nonspecific binding activity at equilibrium. Additionally, the BP ratio of putamen to caudate (PCR) and asymmetric index (ASI) were measured. RESULTS: BPs of NC (3.37+/-0.57, 3.10+/-0.41, 3.23+/-0.48 for caudate, putamen, whole striatum, respectively) had no significant difference with those of essential tremor; ET (3.31+/-0.64, 3.06+/-0.61, 3.14+/-0.63) and Alzheimer's disease; AD (3.33+/-0.60, 3.29+/-0.79, 3.31+/-0.70), but were higher than those of Parkinson's disease; PD (1.92+/-0.74,1.39+/-0.68, 1.64+/-0.68), multiple system atrophy; MSA (2.36+/-1.07, 2.16+/-0.91, 2.26+/-0.96), and dementia with Lewy body; DLB (1.95+/-0.72, 1.64+/-0.65, 1.79+/-0.66)(p<0.005). PD had statistically lower values of PCR and higher values of ASI than those of NC (p<0.005). And PD had significantly lower value of PCR, higher ASI and lower BP in the putamen and whole striatum than MSA (p<0.05). CONCLUSION: Dopamine transporter image of 123I-FP-CIT SPECT was a good value in differential diagnosis of parkinsonism.

The Discriminating Nature of Dopamine Transporter Image in Parkinsonism: The Competency of Dopaminergic Transporter Imaging in Differential Diagnosis of Parkinsonism: 123I-FP-CIT SPECT Study / 핵의학분자영상

PURPOSE: The aim of this study was to evaluate the discriminating nature of 123I-FP-CIT SPECT in patients with parkinsonism. METHODS: 123I-FP-CIT SPECT images acquired from the 18 normal controls; NC (60.4+/-10.0 yr) and 237 patients with parkinsonism (65.9+/-9.2 yr) were analyzed. From spatially normalized images, regional counts of the caudate, putamen, and occipital lobe were obtained using region of interest method. Binding potential (BP) was calculated with the ratio of specific to nonspecific binding activity at equilibrium. Additionally, the BP ratio of putamen to caudate (PCR) and asymmetric index (ASI) were measured. RESULTS: BPs of NC (3.37+/-0.57, 3.10+/-0.41, 3.23+/-0.48 for caudate, putamen, whole striatum, respectively) had no significant difference with those of essential tremor; ET (3.31+/-0.64, 3.06+/-0.61, 3.14+/-0.63) and Alzheimer's disease; AD (3.33+/-0.60, 3.29+/-0.79, 3.31+/-0.70), but were higher than those of Parkinson's disease; PD (1.92+/-0.74,1.39+/-0.68, 1.64+/-0.68), multiple system atrophy; MSA (2.36+/-1.07, 2.16+/-0.91, 2.26+/-0.96), and dementia with Lewy body; DLB (1.95+/-0.72, 1.64+/-0.65, 1.79+/-0.66)(p<0.005). PD had statistically lower values of PCR and higher values of ASI than those of NC (p<0.005). And PD had significantly lower value of PCR, higher ASI and lower BP in the putamen and whole striatum than MSA (p<0.05). CONCLUSION: Dopamine transporter image of 123I-FP-CIT SPECT was a good value in differential diagnosis of parkinsonism.

Hemodynamic Outcome of Successful Bypass Surgery in Patients with Atherosclerotic Cerebrovascular Disease: A study with Acetazolamide and (99m)Tc-ECD SPECT / 핵의학분자영상

PURPOSE: The aim of the study was to evaluate the hemodynamic changes after successful bypass surgery in patients with atherosclerotic stenosis in ICA using (99m)Tc-ECD SPECT. MATERIALS AND METHODS: Fourteen patients (M:F=8:6, mean age; 60+/-9 years) who underwent STA-MCA anastomosis for unilateral atherosclerotic cerebrovascular disease were enrolled. (99m)Tc-ECD basal/acetazolamide perfusion SPECT studies were performed before, 10 days and 6 months after bypass surgery. Perfusion reserve was defined as the % changes after acetazolamide over rest image. Regional cerebral blood flow and perfusion reserve were compared preoperative, early-postoperative and late-postoperative scans. RESULTS: The mean resting perfusion and decrease in perfusion reserve in affected ICA territory on preoperative scan was 52.4+/-3.5 and -7.9+/-4.7%, respectively. The resting perfusion was significantly improved after surgery on early-postoperative scan (mean 53.7+/-2.7) and late-postoperative scan (mean 53.3+/-2.5) compared with preoperative images (p<0.05, respectively). Resting perfusion did not showed further improvement on late-postoperative scan compared with early-postoperative scan. The perfusion reserve was -3.7+/-2.6% on early-postoperative scan, and -1.6+/-2.3% on late-postoperative scan, which was significantly improved after surgery. Additionally, further improvement of perfusion reserved as observed on late-postoperative scan (p<0.05). While, in the unaffected ICA territory, no significant changes in the resting perfusion and perfusion reserve was observed. CONCLUSION: The improvement of resting perfusion and perfusion reserve in early-postoperative scan reflects the immediate restoration of the cerebral blood flow by bypass surgery. In contrasts, further improvement of perfusion reserve showing on late-postoperative scan may indicate a good collateral development after surgery, which may indicate good surgical outcome after surgery.

Diagnostic Accuracy of PET and MR for Detecting Liver Metastasis from Colorectal Cancer / 핵의학분자영상

PURPOSE: Although computed tomography (CT) is widely used for diagnosing liver metastasis from colorectal cancer, diagnostic accuracy of CT is not satisfactory. Magnetic resonance (MR) imaging and F-18 FDG PET has been reported to be superior to CT. However, studies on direct comparison of PET and MR are scarce. We compared the diagnostic accuracy of FDG PET and MR in detecting liver metastasis from colorectal cancer. MATERIALS AND METHODS: Among 363 colorectcal cancer patients who underwent F-18 FDG PET (ECAT, Siemens-CTI, Knoxville; Gemini, Philips, Milpitas, U.S.), 26 patients (M:F=17:9, age=62+/-11) underwent MR to evaluate suspicious metastatic liver lesions. Finally, 35 liver lesions detected by CT from 26 patients were enrolled for analysis. PET and MR results were compared with pathologic reports, clinical findings or follow-up results. RESULTS: Of the 35 lesions, 18 lesions (51.4%) were diagnosed as liver metastases, while remaining 17 (48.6%) as benign. The sensitivity and the specificity of PET were 94.4% and 94.1%, respectively, compared to 100% and 82.4% for MR. MR and PET was concordant in 30 lesions (85.7%): 17 metastatic (94.4%) and 13 benign (76.5%) lesions. ROC curve analysis revealed maximal SUV of 3.1 as the optimum standard in differentiating metastatic from benign liver lesions (AUC=0.897, p<0.001, sensitivity 83.3%, specificity 94.1%). For small lesions less than 1cm in diameter (n=20), diagnostic accuracy of PET was comparable to that of MR. CONCLUSION: F-18 FDG PET showed good diagnostic performance in detecting liver metastasis from colorectal cancer, which was comparable to MR.