Nuclear medicine practice in Japan: a report of the ninth nationwide survey in 2022.

Subcommittee on Survey of Nuclear Medicine Practice in Japan has performed a nationwide survey of nuclear medicine practice every 5 years since 1982 to survey contemporary nuclear medicine practice and its changes over the years. The subcommittee sent questionnaires, including the number and category of examinations as well as the kind of the radiopharmaceuticals during the 30 days of June 2022 to all nuclear medicine institutes in Japan. The total numbers of them for the year 2022 were estimated depends on the 1-month data. A total of 1095 institutes responded to the survey, including 364 positron emission tomography (PET) centers. The recovery rate was 90.6%. The number of gamma cameras installed was 1299 in total, with 2.5% decrease in 5 years. Dual-head cameras and hybrid SPECT/CT scanners accounted for 83.8% and 35.5%, respectively. The number of single-photon tracer studies in 2022 was 1.11 million which means increase in 2.7% in 5 years. Bone scintigraphy was a leading examination (31.0%), followed by myocardial scintigraphy (27.1%) and cerebral perfusion study (23.8%) in order. The percentage of SPECT studies showed an increase from 63.5% in previous survey to 66.8% in this survey. PET centers have also increased from 389 to 412, as compared with the previous one. One hundred and twenty-two PET centers have installed one or two in-house cyclotrons. Increasing trends of the PET studies were observed from 1992 to 2017, the trend changed and PET studies showed 1.5% decrease in 5 years. 18F-FDG accounted for 98.6% (610,497 examinations). PET examinations using 11C-methionine, 13N-NH3 and 11C-PIB have decreased, with 1624, 2146 and 525 examinations, respectively in 2022. The total number of nuclear medicine examination was eventually increased by 1.0%. Therapies for pheochromocytoma or paraganglioma (PPGL) with 131I-MIBG and for neuroendocrine tumor with 177Lu-DOTA-TATE were newly started, however, a total number of targeted radionuclide therapy was decreased by 17.7% because 131I-radioiodine and 223Ra targeted therapies were decreased and supply of some radioisotopes was discontinued. 131I-radioiodine targeted therapy showed a decrease in 5 years (- 15.9%), including 4099 patients for thyroid cancer. The number of out-patient thyroid bed ablation therapy with 1110 MBq of 131I was also decreased to 1015 per year. The number of admission rooms specialized for radionuclide targeted therapy increased from 157 to 160. The number of 223Ra targeted therapies for castration-resistant metastatic prostate cancer (mCRPC) was 1041 patients. This survey was performed during COVID-19 pandemic, however, total number of nuclear medicine examinations was almost same as previous survey (+ 1.0%). Radionuclide therapies with 131I-MIBG and 177Lu-DOTA-TATE were newly started, and new radionuclide therapy will be available in future, therefore, the development of radionuclide therapy will be continued. We are convinced that this survey report is useful in understanding the current status of the nuclear medicine practice in Japan, and in devising the new strategy to strengthen a role of nuclear medicine.

Physiological myocardial 18F-FDG uptake pattern in oncologic PET/CT: comparison with findings in cardiac sarcoidosis.

Objectives: Physiological myocardial 18F-fluorodeoxyglucose (18F-FDG) uptake in oncologic positron emission tomography (PET)/computed tomography (CT) is commonly observed with multiple variations under clinical fasting conditions. The purpose of the present study was to evaluate physiological myocardial 18F-FDG uptake pattern by comparing with the results in cardiac sarcoidosis. Methods: A total of 174 examinations in 174 patients without cardiac disease and 27 examinations in 17 patients with cardiac sarcoidosis were performed. The polar map images generated from 18F-FDG PET/CT data were visually assessed as "basal-ring," "focal," and "focal on diffuse" patterns. Semi-quantitative analysis was also performed using the regional relative 18F-FDG uptake (% uptake). Results: On visual analysis, the "focal on diffuse" pattern was the most common in both examinations (43% and 59%, respectively). The physiological % uptake in the lateral and basal septal walls tended to be higher. Subgroup analysis showed significantly higher uptake in the mid-wall and left circumflex territory. In cardiac sarcoidosis patients, there was a significant difference only between segments 2 and 15 (p=0.04). No significant differences were observed between the base-mid-apical territory and coronary artery branch territory. Conclusion: High 18F-FDG uptake in the basal septal walls is likely to be observed as both physiological uptake in patients without cardiac disease and pathological uptake in patients with cardiac sarcoidosis.

[Accuracy of Injection Dose of Amyloid PET Agent Using Radiopharmaceutical Activity Suppliers].

PURPOSE: This study aimed to identify disposable items with low amyloid positron emission tomography (PET) agent radioactivity adsorption for accurate injections using a radiopharmaceutical activity supplier. METHODS: First, we investigated disposable items currently used for amyloid PET agent injection. Next, we measured the residual radioactivity rates of amyloid PET agents on three-way stopcocks, extension tubes, butterfly needles, and indwelling needles to identify disposable items with low radioactivity adsorption. Finally, we evaluated the accuracy of amyloid PET agent injection using the selected disposable items and a radiopharmaceutical activity supplier. RESULTS: The polybutadiene extension tube exhibited a significantly lower residual activity rate than that of the polyvinyl chloride extension tube. Similarly, the indwelling needles showed significantly lower residual activity rate than that of butterfly needles. The dose indicated by a radiopharmaceutical activity supplier was 184.1 MBq, while the dose calibrator measured the radioactivity which flowed into the vial as 170.2 MBq, resulting in an administration accuracy of 8.2%. CONCLUSION: To ensure accurate amyloid PET agent injections, we recommend using polybutadiene extension tubes and indwelling needles due to their lower radioactivity adsorption.

Administered dosage and effective dose estimated from 81Rb-rubidium hydroxide for lung ventilation scintigraphy using 81mKr noble gas.

The aim of this study was to estimate the administered dosage of 81mKr noble gas as calculated by the radioactivity of 81Rb-rubidium hydroxide (81RbOH). The administered dosage was regarded as the total amount of 81mKr noble gas. The radioactivity of 81mKr was calculated using the radioactivity of 81RbOH at the examination, the beginning of inhalation, the inhalation duration and the attenuation volume from the generator to the patient for 81mKr noble gas. In addition, we created an Internet survey and asked National University Hospital in Japan to respond to questions regarding the parameters of concern. Survey responses were provided by 38 hospitals (response rate was 90.5%). Twenty-seven hospitals (64.3%) examined lung ventilation scintigraphy using 81mKr noble gas. The mean administered dosage and the effective dose of lung ventilation scintigraphy using 81mKr noble gas were 35.8 ± 22.1 GBq and 0.97 ± 0.60 mSv, respectively.

Feasibility of whole-body 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography angiography using continuous bed motion in patients with vascular disease: a pilot study.

OBJECTIVE: Positron emission tomography (PET) angiography is a promising PET imaging method for vessel evaluation. With advances in PET technologies, PET angiography of the whole body is now possible using continuous bed motion (CBM) mode. This study aimed to evaluate the image quality for depicting the aorta and main branches and the diagnostic performance of whole-body PET angiography in patients with vascular disease. METHODS: We retrospectively identified 12 consecutive patients who underwent whole-body 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) PET angiography in CBM mode. Whole-body PET angiography was performed between 20 and 45 s after administering [18F]FDG using CBM from the neck to the pelvis. The visibility of whole-body PET angiography was assessed for the 24 segments in three regions per patient using a 4-point grading scale (1, unacceptable; 2, poor; 3, good; 4, excellent), and grades 3 and 4 were considered diagnostic. The diagnostic accuracy of whole-body PET angiography for detecting vascular abnormalities was calculated using contrast-enhanced CT as a reference standard. RESULTS: We evaluated 285 segments from 12 patients, and overall, 170/285 segments (60%) were considered diagnostic throughout the whole body, including 96/117 (82%), 22/72 (31%), and 52/96 (54%) segments in the neck-to-chest region, abdominal region, and pelvic region, respectively. The sensitivity, specificity, and accuracy of whole-body PET angiography for detecting vascular abnormalities were 75.9%, 98.8%, and 96.5%, respectively. CONCLUSIONS: Whole-body PET angiography showed a better image quality for the neck-to-chest and pelvic regions in this setting, although it provided limited information on the vessels in the abdominal region.

Quantitative [99mTc]Tc-MDP SPECT/CT correlated with [18F]NaF PET/CT for bone metastases in patients with prostate cancer.

BACKGROUND: The purpose of the present study was to elucidate the correlation between standardized uptake value (SUV) and volume-based parameters measured by quantitative [99mTc]Tc-methylene diphosphonate (MDP) single photon emission computed tomography (SPECT)/CT and [18F]-sodium fluoride ([18F]NaF) positron emission tomography (PET)/CT in the assessment of bone metastases in patients with prostate cancer. METHODS: The study included 26 male prostate cancer patients with confirmed or suspected bone metastases who underwent both [99mTc]Tc-MDP SPECT/CT and [18F]NaF PET/CT studies. Skeletal lesions visible on both SPECT/CT and PET/CT were classified as benign or metastases. The maximum SUV (SUVmax), peak SUV (SUVpeak), mean SUV (SUVmean), metabolic bone volume (MBV), and total bone uptake (TBU) were calculated for every lesion showing abnormal uptake. RESULTS: A total of 202 skeletal lesions (147 benign and 55 metastases) were detected in the 26 patients. Strong significant correlations were noted between SPECT/CT and PET/CT for the SUV- and volume-based parameters (all P < 0.001). The SUVmax, SUVpeak, SUVmean, and TBU values obtained with SPECT/CT were significantly lower than the corresponding values obtained with PET/CT (all P < 0.001). The MBV in SPECT/CT was significantly higher than that in PET/CT (P < 0.001). All SUV- and volume-based parameters obtained with both SPECT/CT and PET/CT for metastatic lesions were significantly higher than the corresponding parameters for benign lesions (P values from 0.036 to < 0.001). CONCLUSIONS: These preliminary results demonstrate that the SUV- and volume-based parameters for bone uptake obtained with quantitative SPECT/CT and PET/CT are strongly correlated in patients with prostate cancer. The SUV parameters obtained with SPECT/CT were significantly lower than those obtained with PET/CT, whereas the uptake volume obtained with SPECT/CT was significantly higher than that obtained with PET/CT.

Relationship between [18F]FDG PET/CT and metabolomics in patients with colorectal cancer.

INTRODUCTION: Advances in metabolomics have significantly improved cancer detection, diagnosis, treatment, and prognosis. OBJECTIVES: To investigate the relationship between metabolic tumor volume (MTV) using 2-deoxy-2-[18F]fluoro-D-glucose (FDG) positron emission tomography (PET)/ computed tomography (CT) and metabolomics data in patients with colorectal cancer (CRC). METHODS: The metabolome in tumor tissues was analyzed using capillary electrophoresis time-of-flight mass spectrometry in 33 patients with newly diagnosed CRC who underwent FDG PET/CT before treatment and had tumor tissue post-surgery. Based on the FDG PET data, MTV was calculated and was dichotomized according to the median value, and tumors were divided into low-MTV and high-MTV tumors. Metabolomics data were compared between the low-MTV and high-MTV tumors. RESULTS: The levels of most glycolysis-related metabolites were not different between low-MTV and high-MTV tumors. The level of component of the initial part of the tricarboxylic acid (TCA) cycle, citrate, was significantly lower in the high-MTV tumor than in the low-MTV tumor. The TCA intermediate succinate level was significantly higher in the high-MTV tumor than in the low-MTV tumor. In contrast, the TCA intermediate fumarate level was significantly lower in the high-MTV tumor than in the low-MTV tumor. The levels of many amino acids were significantly higher in the high-MTV tumor than in the low-MTV tumor. CONCLUSIONS: Although preliminary, these results suggest that tumors with high FDG metabolism in CRC may obtain more energy by using a reverse reaction of the TCA cycle and amino-acid metabolism. However, further research is required to clarify this relationship.

[Creation of a Stereo-paired Bone Anatomical Chart Using Human Bone Specimens for X-ray Anatomical Education Part III: Addition of Anaglyph Three-dimensional Images for Those Who Hardly See Stereo-paired Photographs with the Naked Eye].

We published a report entitled "Creation of a stereo-paired bone anatomical chart using human bone specimen for radiation education" in this journal in order to accurately understand the surface structure and three-dimensional structure of bones, and assist in bone image interpretation. However, some people cannot see stereoscopically with the naked eye. Therefore, we created anaglyph three-dimensional (3D) images from stereo-paired images of the stereo X-ray anatomical chart of the bone specimen. The anaglyph of the bone surface and X-ray images facilitates stereoscopic viewing with red-blue 3D glasses. The stereo X-ray anatomical chart of the bone specimen with anaglyph 3D images was converted into an electronic data file in the same manner as the stereo X-ray anatomical chart of the bone specimen, which can be easily used in any radiological examination rooms or at home through an electronic medium. We made it possible to perform correlative stereoscopic observations of the bone surface and X-ray images using red-blue 3D glasses.

[Creation of Bone X-ray Radiography Manual Using Human Bone Specimens for Bone X-ray Radiography Education].

Senior radiological technologists have made various improvements and have supported the clinical and educational fields by explaining bone X-ray radiography to students and junior radiological technologists to understand the procedure using illustrations, X-ray images, and photographs in a way that corresponds to the design software available for that era. Because human bone specimens are only available in the anatomy laboratory of medical schools, they could not be used for the explanation of bone X-ray radiography until now. Therefore, we have developed a bone X-ray radiography manual using bone specimens for the bone X-ray radiography education, which helps students to understand the procedure of bone X-ray radiography. Previous bone X-ray radiography manuals had not been illustrated by bone specimens and bone specimen X-ray images, but this bone X-ray radiography manual using bone specimens has made it possible to understand the surface morphology of bone specimens and X-ray images of them. In addition, the data of bone X-ray radiography using this bone specimen were made into an electronic file, which can be easily used at the place of radiological examination or at home through electronic media.

[Creation of Stereo-paired Color Vascular Anatomical Charts Using 3-dimentional Images].

Three-dimensional (3D) images of blood vessels in the human body, which are acquired by X-ray computed tomography (CT) and cone-beam CT of Angiography devices, are widely used in medical diagnosis and treatment. Using the 3DCT images of blood vessels, we created stereo-paired color vascular anatomical charts for better understanding of vascular anatomy in clinical settings, patient explanations, and student education. Since it is difficult to distinguish branches of blood vessels that show three-dimensionally complicated running such as cerebral blood vessels, we made it easier to identify them anatomically by color-coding each branch of the blood vessel. Also, by using stereo-paired images, we can see the three-dimensional blood vessel running. In the past anatomical books and vascular anatomy atlas, there was no anatomical chart of the whole body blood vessels that could be color-coded and stereoscopically viewed. We have made it possible to identify blood vessels by the stereoscopic vision of the blood vessels using this stereo-paired color anatomical chart. In addition, this vascular anatomical chart can be additionally revised according to the needs of the clinical and educational settings to be used, and the data can be converted into an electronic file so that it can be easily used in the field of radiological examination or at home through electronic media.

Fractal analysis of 11C-methionine PET in patients with newly diagnosed glioma.

BACKGROUND: The present study tested the possible utility of fractal analysis from L-[methyl-11C]-methionine (MET) uptake in patients with newly diagnosed gliomas for differentiating glioma, especially in relation to isocitrate dehydrogenase 1 (IDH1) mutation status, and as compared with the conventional standardized uptake value (SUV) parameters. METHODS: Investigations of MET PET/CT were performed retrospectively in 47 patients with newly diagnosed glioma. Tumors were divided into three groups: lower grade glioma (IDH1-mutant diffuse astrocytoma and IDH1-mutant anaplastic astrocytoma), higher grade glioma (IDH1-wildtype diffuse astrocytoma and IDH1-wildtype anaplastic astrocytoma), and glioblastoma. The fractal dimension for tumor, maximum SUV (SUVmax) for tumor (T) and mean SUV for normal contralateral hemisphere (N) were calculated, and the tumor-to-normal (T/N) ratio was determined. Metabolic tumor volume (MTV) and total lesion MET uptake (TLMU) were also measured. RESULTS: There were significant differences in SUVmax (p = 0.006) and T/N ratio (p = 0.02) between lower grade glioma and glioblastoma. There were no significant differences among any of the three groups in MTV or TLMU. Significant differences were obtained in the fractal dimension between lower grade glioma and higher grade glioma (p = 0.006) and glioblastoma (p < 0.001). CONCLUSIONS: The results of this preliminary study in a small patient population suggest that the fractal dimension using MET PET in patients with newly diagnosed gliomas is useful for differentiating glioma, especially in relation to IDH1 mutation status, which has not been possible with SUV parameters.

[Investigation of the Administration Accuracy of an Auto Infusion Device in 18F-FDG PET].

PURPOSE: The administration accuracy of the automated infusion device for the positron emission radiopharmaceutical affects to calculation of the standardized uptake value (SUV) in 18F-fluorodeoxyglucose (18F-FDG) PET examination. The purpose of this study was to investigate the administration error in the clinical use of an automated infusion device for quantitative management in PET examination. METHODS: We assumed clinical use of the automated infusion device and investigated two types of administration errors. First, for investigating the administration error over time in a day (errorday), a total of 13 infusion works were performed every 30 minutes. Second, for investigating the long period administration error (errorperiod), the infusion work was performed once before clinical use of an automated infusion device. The dispensed radioactivity was set to 150 MBq. The administration error was calculated using output values from the automated infusion device and measured values from the dose calibrator. RESULTS: The administration errorday was 0.9±1.3%, and the maximum error was 2.7%. The administration errorperiod was 1.1±2.0%, and the maximum error was 5.9%. CONCLUSION: We investigated the administration error of the automated infusion device. We confirmed the approximately 1% administration error and high-accuracy injection in an automated-device method.

Correlation of 4'-[methyl-11C]-thiothymidine PET with Gd-enhanced and FLAIR MRI in patients with newly diagnosed glioma.

PURPOSE: To elucidate the biological association between tumor proliferation, tumor infiltration and neovascularization, we analyzed the association between volumetric information of 4'-[methyl-11C]thiothymidine (4DST) positron emission tomography (PET) and fluid-attenuated inversion recovery (FLAIR) and T1-weighted gadopentetate dimeglumine (Gd)-enhanced magnetic resonance imaging (MRI), in patients with newly diagnosed glioma. METHODS: A total of 23 patients with newly diagnosed glioma who underwent both 4DST PET/CT and Gd-enhanced MRI before therapy were available for a retrospective analysis of prospectively collected data. The maximum standardized uptake value (SUVmax) for tumor (T) and the mean SUV for normal contralateral hemisphere (N) were calculated, and the tumor-to-normal (T/N) ratio was determined. Proliferative tumor volume (PTV) from 4DST PET and the volume of Gd enhancement (GdV) and hyperintense region on FLAIR (FLAIRV) from MRI were calculated. RESULTS: All gliomas but 3 diffuse astrocytomas and one anaplastic astrocytoma had 4DST uptake and Gd enhancement on MRI. There was no significant difference between PTV and GdV although the exact edges of the tumor differed in each modality. The FLAIRV was significantly larger than PTV (P < 0.001). Significant correlations between PTV and GdV (ρ = 0.941, P < 0.001) and FLAIRV (ρ = 0.682, P < 0.001) were found. CONCLUSION: These preliminary results indicate that tumor proliferation assessed by 4DST PET is closely associated with tumor-induced neovascularization determined by Gd-enhanced MRI in patients with newly diagnosed glioma.

[Creation of a Stereo-paired Bone Anatomical Chart Using Human Bone Specimens for X-ray Anatomical Education Part II: Addition of Stereo-paired X-ray Bone Images to the Anatomical Chart].

In a previous issue of this journal, we published a report entitled "Creation of Stereo-paired Bone Anatomical Charts Using Human Bone Specimens for Radiation Education" To understand how the bone specimen is visualized as an X-ray image, we newly created a bone specimen stereo-paired X-ray anatomical chart by adding the X-ray images of the same bone specimen. When a bone is X-rayed, the surface structure and internal structure of the bone are visualized as a composite image of the difference in X-ray absorption, and each bone becomes a unique X-ray image. Therefore, we took stereo-paired X-ray images of the bone specimens by the same method as the stereo-paired anatomical chart of the bone specimens. Then, we arranged the stereo-paired X-ray images and surface images of the same bone specimen in the one sheet to be readily compared. Similar to the previous bone specimen anatomical charts, these data of X-ray image anatomical chart were also made into an electronic file, so that we can do the three-dimensional observation of bone X-ray images even at the place of radiological examination or at home through electronic media. Until now, none of the specialized anatomy books and pictorial books are available for stereoscopic viewing of bone specimens and bone X-ray images. However, this stereo-paired X-ray image anatomical chart enabled us to learn accurate three-dimensionalization of bones by comparing the bone surface morphology and bone X-ray images.

Effect of quantitative values on shortened acquisition duration in brain tumor 11C-methionine PET/CT.

BACKGROUND: The amount of signal decreases when the acquisition duration is shortened. However, it is not clear how this affects the quantitative values. This study aims to clarify the effect of acquisition time shortening in brain tumor PET/CT using 11C-methionine on the quantitative values. METHOD: This study was a retrospective analysis of 30 patients who underwent clinical 11C-methionine PET/CT examination. PET images were acquired in list mode for 10 min. PET images of acquisition duration from 1 to 10 min with 1-min step were reconstructed. We examined the effect on the quantitative values of acquisition duration. We placed a volume of interest to include the entire tumor and regions of interest in the shape of a large crescent in the contralateral hemisphere in 5 contiguous axial slices as normal tissue. Quantitative values examined were maximum, peak, and mean standardized uptake values (SUVmax, SUVpeak, SUVmean), metabolic tumor volume (MTV), and maximum tumor to normal tissue ratio (TNRmax), with each duration compared to that with 10 min. RESULTS: SUVmax, MTV, and TNRmax showed the highest values due to the effects of statistical noise when the acquisition time was 1 min. These values were stable when the acquisition duration was > 6 min. SUVpeak and SUVmean showed mostly consistent values regardless of duration. CONCLUSIONS: SUVmax, MTV, and TNRmax are affected by acquisition time. If the acquisition duration was > 6 min, the fluctuation could be suppressed within 5% in these quantitative values. However, SUVpeak was suggested to be a robust index regardless of the acquisition duration.