Comparison of Image Quality and Semi-quantitative Measurements with Digital PET/CT and Standard PET/CT from Different Vendors / 대한핵의학회잡지

Purpose@#This study aimed to evaluate the concordance and equivalence of results between the newly acquired digital PET/ CT(dPET) and the standard PET/CT (sPET) to investigate possible differences in visual and semi-quantitative analyses. @*Methods@#A total of 30 participants were enrolled and underwent a single 18F-FDG injection followed by dual PET/CT scans, by a dPET scan, and immediately after by the sPET scan or vice versa. Two readers reviewed overall image quality using a 5-point scale and counted the number of suggestive 18F-FDG avid lesions. The SUV values were measured in the background organs and in hypermetabolic target lesions. Additionally, we objectively evaluated image quality using the liver signal-to-noise ratio (SNR). @*Results@#The dPET identified 4 additional 18F-FDG avid lesions in 3 of 30 participants with improved visual image quality. The standard deviations of SUV of the background organs were significantly lower with Digital PET than with sPET, and dPET could acquire images with better SNR (11.13 ± 2.01 vs. 8.71 ± 1.32, P < 0.001). The reliability of SUV values between scanners showed excellent agreement. Bland-Altman plot analysis of 81 lesions showed an acceptable agreement between scanners for most of the SUVmax and SUVpeak values. No relationship between the SUV values and time delays of dual PET/CT acquisition was found. @*Conclusions@#The dPET provides improved image quality and lesion detectability than the sPET. The semi-quantitative values of the two PET/CT systems of different vendors are comparable. This pilot study will be an important basis for possible interchangeable use of either system in clinical practice.

Computed Tomography (CT) Protocols Associated with Cardiac and Bone Single-Photon Emission Computed Tomography/CT (SPECT/CT) in Korea / 대한핵의학회잡지

Purpose@#Single-photon emission computed tomography/computed tomography (SPECT/CT) is an advanced hybrid nuclear medicine technology that generates both functional and anatomical images in a single study. As utilization of SPECT/CT in Korea has been increasing, the purpose of this study was to survey its application of cardiac and skeletal SPECT/CT imaging for protocol optimization. @*Methods@#We surveyed CT protocols established for cardiac and skeletal SPECT/CT. We searched the guidelines for the CT protocols for SPECT/CT and reviewed the literature recently published. @*Results@#Among 36 hybrid SPECT scanners equipped with four or more multi-channel detector CTs (MDCTs), 18 scanners were used to perform cardiac studies at both very low current CT (30–80 mA; 11.1%) and ultra-low current CT (13–30 mA; 88.9%). Among the 33 canners, very low current (≤ 80 mA) CT or low current CT (80–130 mA) was used in 23.5%, and 41.8% for spine disorders, and in 36.4% or 30.3% for foot/ankle disorders, respectively. In the CT reconstructions, slice thickness of 5 mm for cardiac studies was most commonly used (94.4%); thinner slices (0.6–1.0 mm) for spine and foot/ankle studies were used in 24.2% and 45.5%, respectively. We also reviewed the international guidelines. @*Conclusions@#The results and current recommendations will be helpful for optimizing CT protocols for SPECT/CT. Optimization of SPECT/CT protocols will be required for generating the proper strategy for the specific lesions and clinical purpose.

KSNM/KSID/KOSHIC Guidance for Nuclear Medicine Department Against the Coronavirus Disease 2019 (COVID-19) Pandemic / 대한핵의학회잡지

The dramatic spread of Coronavirus Disease 2019 (COVID-19) has profound impacts on every continent and life. Due to humanto-human transmission of COVID-19, nuclear medicine staffs also cannot escape the risk of infection from workplaces. Everystaff in the nuclear medicine department must prepare for and respond to COVID-19 pandemic which tailored to the characteristicsof our profession. This article provided the guidance prepared by the Korean Society of Nuclear Medicine (KSNM) incooperation with the Korean Society of Infectious Disease (KSID) and Korean Society for Healthcare-Associated InfectionControl and Prevention (KOSHIC) in managing the COVID-19 pandemic for the nuclear medicine department.We hope that thisguidance will support every practice in nuclear medicine during this chaotic period.

Prognostic Value of Restaging F-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography to Predict 3-Year Post-Recurrence Survival in Patients with Recurrent Gastric Cancer after Curative Resection

Objective@#The aim of this study was to investigate the prognostic value of the maximum standardized uptake value (SUVmax) measured while restaging with F-18 fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/ CT) to predict the 3-year post-recurrence survival (PRS) in patients with recurrent gastric cancer after curative surgical resection. @*Materials and Methods@#In total, 47 patients with recurrent gastric cancer after curative resection who underwent restaging with 18F-FDG PET/CT were included. For the semiquantitative analysis, SUVmax was measured over the visually discernable 18F-FDG-avid recurrent lesions. Cox proportional-hazards regression models were used to predict the 3-year PRS. Differences in 3-year PRS were assessed with the Kaplan–Meier analysis. @*Results@#Thirty-nine of the 47 patients (83%) expired within 3 years after recurrence in the median follow-up period of 30.3 months. In the multivariate analysis, SUVmax (p = 0.012), weight loss (p = 0.025), and neutrophil count (p = 0.006) were significant prognostic factors for 3-year PRS. The Kaplan–Meier curves demonstrated significantly poor 3-year PRS in patients with SUVmax > 5.1 than in those with SUVmax ≤ 5.1 (3-year PRS rate, 3.5% vs. 38.9%, p < 0.001). @*Conclusion@#High SUVmax on restaging with 18F-FDG PET/CT is a poor prognostic factor for 3-year PRS. It may strengthen the role of 18F-FDG PET/CT in further stratifying the prognosis of recurrent gastric cancer.

Genetic features associated with ¹⁸F-FDG uptake in intrahepatic cholangiocarcinoma

PURPOSE: In intrahepatic cholangiocarcinoma (iCCA), genetic characteristics on ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG)-PET scans are not yet clarified. If specific genetic characteristics were found to be related to FDG uptake in iCCA, we can predict molecular features based on the FDG uptake patterns and to distinguish different types of treatments. In this purpose, we analyzed RNA sequencing in iCCA patients to evaluate gene expression signatures associated with FDG uptake patterns. METHODS: We performed RNA sequencing of 22 cases iCCA who underwent preoperative ¹⁸F-FDG-PET, and analyzed the clinical and molecular features according to the maximum standard uptake value (SUVmax). Genes and biological pathway which are associated with SUVmax were analyzed. RESULTS: Patients with SUVmax higher than 9.0 (n = 9) had poorer disease-free survival than those with lower SUVmax (n = 13, P = 0.035). Genes related to glycolysis and gluconeogenesis, phosphorylation and cell cycle were significantly correlated with SUVmax (r ≥ 0.5). RRM2, which is related to the toxicity of Gemcitabine was positively correlated with SUVmax, and SLC27A2 which is associated with Cisplastin response was negatively correlated with SUVmax. According to the pathway analysis, cell cycle, cell division, hypoxia, inflammatory, and metabolism-related pathways were enriched in high SUVmax patients. CONCLUSION: The genomic features of gene expression and pathways can be predicted by FDG uptake features in iCCA. Patients with high FDG uptake have enriched cell cycle, metabolism and hypoxic pathways, which may lead to a more rational targeted treatment approach.

Recent Trends in Nuclear Cardiology Practice / 전남의대학술지

Over the past three decades, radionuclide myocardial perfusion scintigraphy (MPS) has become established as the main functional cardiac imaging technique for ischemic heart disease. It is currently appropriate for all aspects of detecting and managing ischemic heart disease, including diagnosis, risk assessment and stratification, assessment of myocardial viability, and evaluation of left ventricular function. The purpose of this article was to review recent trends in nuclear cardiology practice, excluding positron emission tomography. The past few years have brought several rapid developments that have increased photon sensitivity in nuclear cardiology scanner hardware. Additionally, software applying new methods of single photon emission tomography (SPECT) reconstruction on conventional and dedicated systems has preserved or even improved SPECT image quality with lower count statistics. On the other hand, much interest has been shown in lowering the radiation dose by the stakeholders of MPS.

Recent Trends in Nuclear Cardiology Practice / 전남의대학술지

Over the past three decades, radionuclide myocardial perfusion scintigraphy (MPS) has become established as the main functional cardiac imaging technique for ischemic heart disease. It is currently appropriate for all aspects of detecting and managing ischemic heart disease, including diagnosis, risk assessment and stratification, assessment of myocardial viability, and evaluation of left ventricular function. The purpose of this article was to review recent trends in nuclear cardiology practice, excluding positron emission tomography. The past few years have brought several rapid developments that have increased photon sensitivity in nuclear cardiology scanner hardware. Additionally, software applying new methods of single photon emission tomography (SPECT) reconstruction on conventional and dedicated systems has preserved or even improved SPECT image quality with lower count statistics. On the other hand, much interest has been shown in lowering the radiation dose by the stakeholders of MPS.

Usefulness of F-18 FDG PET/CT in Adrenal Incidentaloma: Differential Diagnosis of Adrenal Metastasis in Oncologic Patients / 핵의학분자영상

PURPOSE: We have evaluated characteristics of adrenal masses incidentally observed in nonenhanced F-18 FDG PET/CT of the oncologic patients and the diagnostic ability of F-18 FDG PET/CT to differentiate malignant from benign adrenal masses. MATERIALS AND METHODS: Between Mar 2005 and Aug 2008, 75 oncologic patients (46 men, 29 women; mean age, 60.8+/-10.2 years; range, 35-87 years) with 89 adrenal masses incidentally found in PET/CT were enrolled in this study. For quantitative analysis, size (cm), Hounsfield unit (HU), maximum standardized uptake value (SUVmax), SUVratio of all 89 adrenal masses were measured. SUVmax of the adrenal mass divided by SUVliver, which is SUVmax of the segment 8, was defined as SUVratio. The final diagnosis of adrenal masses was based on pathologic confirmation, radiologic evaluation (HU<0 : benign), and clinical decision. RESULTS: Size, HU, SUVmax, and SUVratio were all significantly different between benign and malignant adrenal masses.(P < 0.05) And, SUVratio was the most accurate parameter. A cut-off value of 1.0 for SUVratio provided 90.9% sensitivity and 75.6% specificity. In small adrenal masses (1.5 cm or less), only SUVratio had statistically significant difference between benign and malignant adrenal masses. Similarly a cut-off value of 1.0 for SUVratio provided 80.0% sensitivity and 86.4% specificity. CONCLUSION: F-18 FDG PET/CT can offer more accurate information with quantitative analysis in differentiating malignant from benign adrenal masses incidentally observed in oncologic patients, compared to nonenhanced CT.

Diagnostic Role of F-18 FDG PET/CT in the Follow-up of Patients with Colorectal Cancer: Comparison with Serum CEA, CA 19-9 Levels and Computed Tomography / 핵의학분자영상

PURPOSE: Early detection of recurrence is an important factor for long term survival of patients with colorectal cancer. Measurement of serum levels of CEA, CA 19-9, CT and PET/CT has been commonly used in the postoperative surveillance of colorectal cancer. The purpose of this study was to compare the diagnostic ability of PET/CT, tumor marker and CT for recurrence in colorectal cancer patients after treatment. MATERIALS AND METHODS: F-18 FDG PET/CT imaging was performed in 189 colorectal cancer patients who underwent curative surgical resection and/or chemotherapy. Measurement of serum levels of CEA, CA 19-9 and CT imaging were performed within 2 months of PET/CT examination. Final diagnosis of recurrence was made by biopsy, radiologic studies or clinical follow-up for 6 months after each study. RESULTS: Overall sensitivity, specificity of PET/CT was 94.7%, 91.1%, while those of serum CEA were 44.7% and 97.3%, respectively. Sensitivity and specificity were 94.2%, 90.4% for PET/CT and better than those of combined CEA and CA 19-9 measurement (52.1%, 88.5%) in 174 patients measured available both CEA and CA 19-9 data. In 115 patients with both tumor markers and CT images available, PET/CT showed similar sensitivity but higher specificity (92.9%, 91.3%) compared to combination of tumor markers and CT images (92.9%, 74.1%). CONCLUSION: PET/CT was superior for detection of recurred colorectal cancer patients compared with both CEA, CA 19-9, and even with combination of both tumor markers and CT. Therefore PET/CT could be used as a routine surveillance examination to detect recurrence or metastasis of colorectal cancer.

Optimal Imaging Time for Diagnostic I-123 Whole Body Scan in the Follow-up of Patients with Differentiated Thyroid Cancer: Comparison between 6- and 24-Hour Images of the Same Subjects / 핵의학분자영상

PURPOSE: To determine optimal imaging time for diagnostic I-123 whole body scan in the follow-up of patients with differentiated thyroid cancer (DTC), we compared the image quality of 6- and 24-hour images of the same subjects. MATERIALS AND METHODS: Four hundred ninety-eight patients (M:F=55:443, Age 47.6+/-12.9 years) with DTC who had undergone total thyroidectomy and I-131 ablation therapy underwent diagnostic whole body scanning 6 hour and 24 hour after oral ingestion of 185 MBq (5 mCi) of I-123. Serum thyroglobulin measurement and ultrasonography of the neck were performed at the time of imaging. In 40 patients underwent additional I-131 therapy, post-therapy I-131 images were obtained and compared with diagnostic I-123 images. RESULTS: In 440 patients (88.4%), 6- and 24-hour diagnostic I-123 images were concordant, and 58 patients (11.6%) showed discordant findings. Among 58 discordant patients, 31 patients showed abnormal tracer uptake on only 6-hour image, which turned out false-positive findings in all cases. In 12 patients with positive findings on only 24-hour image, remnant thyroid tissue (4 patients) and cervical lymph node metastasis (3 patients) were presented. Among 40 patients underwent additional I-131 therapy, 6-hour and 24-hour images were discordant in 13 patients. All 5 patients with abnormal uptake on only 6-hour image revealed false-positive results, whereas most of 24-hour images were concordant with post-therapy I-131 images. CONCLUSION: I-123 imaging at 24-hour could reduce false-positive findings and improve diagnostic accuracy, compared with 6-hour image in the follow-up of patient with DTC.