Voxel‑Based Internal Dosimetry for 177 Lu‑Labeled Radiopharmaceutical Therapy Using Deep Residual Learning / 대한핵의학회잡지

Purpose@#In this study, we propose a deep learning (DL)–based voxel-based dosimetry method in which dose maps acquired using the multiple voxel S-value (VSV) approach were used for residual learning. @*Methods@#Twenty-two SPECT/CT datasets from seven patients who underwent 177 Lu-DOTATATE treatment were used in this study. The dose maps generated from Monte Carlo (MC) simulations were used as the reference approach and target images for network training. The multiple VSV approach was used for residual learning and compared with dose maps generated from deep learning. The conventional 3D U-Net network was modified for residual learning. The absorbed doses in the organs were calculated as the mass-weighted average of the volume of interest (VOI). @*Results@#The DL approach provided a slightly more accurate estimation than the multiple-VSV approach, but the results were not statistically significant. The single-VSV approach yielded a relatively inaccurate estimation. No significant difference was noted between the multiple VSV and DL approach on the dose maps. However, this difference was prominent in the error maps. The multiple VSV and DL approach showed a similar correlation. In contrast, the multiple VSV approach underestimated doses in the low-dose range, but it accounted for the underestimation when the DL approach was applied. @*Conclusion@#Dose estimation using the deep learning–based approach was approximately equal to that in the MC simulation. Accordingly, the proposed deep learning network is useful for accurate and fast dosimetry after radiation therapy using 177 Lu-labeled radiopharmaceuticals.

Preclinical Voxel-Based Dosimetry in Theranostics: a Review / 대한핵의학회잡지

Due to the increasing use of preclinical targeted radionuclide therapy (TRT) studies for the development of novel theranosticagents, several studies have been performed to accurately estimate absorbed doses to mice at the voxel level using referencemouse phantoms and Monte Carlo (MC) simulations. Accurate dosimetry is important in preclinical theranostics to interpretradiobiological dose-response relationships and to translate results for clinical use. Direct MC (DMC) simulation is believed toproduce more realistic voxel-level dose distribution with high precision because tissue heterogeneities and nonuniform sourcedistributions in patients or animals are considered. Although MC simulation is considered to be an accurate method for voxelbasedabsorbed dose calculations, it is time-consuming, computationally demanding, and often impractical in daily practice. Inthis review, we focus on the current status of voxel-based dosimetry methods applied in preclinical theranostics and discuss theneed for accurate and fast voxel-based dosimetry methods for pretherapy absorbed dose calculations to optimize the dosecomputation time in preclinical TRT.

Alterations in Spontaneous Movement, Corticosterone, and Cytokines in Mice Exposed to 835 MHz Radiofrequency Radiation / 체질인류학회지

Although commercialization of mobile phones has raised much concerns about the effects of radiofrequency radiation on the human body, few experimental studies have been conducted on the effects of radiofrequency radiation on physiological homeostasis, immune and inflammatory responses. Therefore, we presently investigated the effect of 835 MHz radiofrequency radiation on spontaneous wheel exercise, hormone and cytokines levels in the plasm of mice. Mice were divided into 4 groups as control, exercise, radiofrequency radiation, radiofrequency radiation & exercise group. The body weight, corticosterone and blood cytokine levels were checked for 10 weeks. Followed by the exposure to radiofrequency radiation for 6 hours a day, the more increase in body weight was observed in the radiofrequency radiation & exercise group than in the spontaneous exercise group. When the amount of spontaneous exercise was measured for 10 weeks, the amount of exercise was increased in the both control and spontaneous exercise group, while the amount of exercise was decreased in the radiofrequency radiation group. To determine whether the homeostasis, immune and inflammatory responses are indirectly affected by radiofrequency radiation exposure, IL-1β, IL-6, IL-12 (p70), TNF-α, IFNγ, and GM-CSF were measured by ELISA kit, respectively. As a result, the blood levels of IL-6, IL-12 (p70) and TNF-α in the spontaneous exercise group were higher than that of control group, and each cytokine levels in the radiofrequency radiation & exercise group were lower than that of control group. However, the corticosterone, IL-1β, IFNγ and GM-CSF didn't show statistically significant differences in all groups. It has been confirmed that exposure to high frequency electromagnetic waves for a long time can affect the amount of exercise, body weight, and some inflammatory cytokines such as IL-6, IL-12 (p70) and TNF-α.

Photodynamic bactericidal effect against Enterococcus faecalis by erythrosine concentration and LED irradiation times / 대한구강보건학회지

OBJECTIVES: The purpose of this study was to provide photodynamic bactericidal effect against Enterococcus faecalis by erythrosine concentrations and LED irradiation times. METHODS: Erythrosine was used as a photosensitizer and green LED (3 Watt, 520-530 nm) was used as light source. E. faecalis ATCC 1943 and E. faecalis ATCC 29212 were used in this study. Approximately 10(5) CFU of bacteria were added in wells of a 96-well microtitration plate. For examining the effects of concentrations of erythrosine, 0, 0.625, 1.25, 2.5, 5, and 10 microM of erythrosine were added in wells containing bacteria. The irradiation time with LED was 30 sec. In another set of experiment, the effect of irradiation time for killing of bacteria was investigated by increasing irradiation time from 0 to 30 s with 10 microM of erythrosine final concentration. After irradiation, each sample was serially diluted with PBS and 50 microl of diluents was spread on duplicate blood agar plates. The plates were incubated for 72 h at 37degrees C under aerobic conditions and the number of CFU was determined. The experiments were repeated four times. The results were analyzed using one-way ANOVA, and Tukey's multiple comparison at a significance level of 0.05. RESULTS: When the erythrosine concentrations were more than 2.5 microM, E. faecalis ATCC 29212 was significantly decreased (P<0.05). The more erythrosine concentrations increased, the more E. faecalis ATCC 1943 decreased statistically significantly (P<0.05). In another set of experiment, when LED irradiation time was more than 20 s, E. faecalis ATCC 1943 decreased significantly (P<0.05), and if the irradiation times was more than 5 s, E. faecalis ATCC 29212 decreased significantly (P<0.05). CONCLUSIONS: PDT using erythrosine and green LED was found to be an effective method in killing E. faecalis.

A study on the correlation between urinary fluoride/creatinine ratio, fluoride concentration of drinking water, urine and fingernail in preschool children / 대한구강보건학회지

OBJECTIVES: This study aimed to confirm the efficacy of the urinary fluoride concentration/creatinine ratio for monitoring fluorine intake in fluoridated and non-fluoridated communities. METHODS: The correlations among the fluoride concentration in drinking water and that in the urine and fingernails of 52 preschool children (age, 60-72 months) from fluoridated and non-fluoridated communities were analyzed. RESULTS: The urinary fluoride concentration/creatinine ratio had a relatively high correlation with the fluoride concentration in drinking water (Pearson's correlation coefficient, 0.606; P0.05). CONCLUSIONS: The findings of this study suggest that the urinary fluoride concentration/creatinine ratio in children can be utilized as an index for monitoring excess fluoride intake in fluoridated communities.

The remineralization effect of topical fluoride agents on artificial enamel caries / 대한구강보건학회지

OBJECTIVES: The aim of this study was to compare the remineralization effect of the topical fluoride agents on artificial enamel caries, under the chemical pH cycling model, using surface microhardness. METHODS: Bovine enamel specimens, embedded in acrylic resin with the labial surfaces exposed, were developed artificial enamel caries. Thereafter, this study used 56 samples on VHN 25-45. The experimental groups were divided into 4 groups: control, 2% NaF solution, 1.23% APF gel, 5% NaF varnish. Samples, except in the control group, were applied to each topical fluoride agent for 4 minutes. All groups were exposed to a pH cycling model, which consisted of demineralization (4 hours) and remineralization (20 hours) for 17 days. The Vickers surface microhardness number (VHN) was measured, using the microhardness tester. The results were analyzed, using a repeated measures analysis of variance of a general linear model, and compared the baseline, each day, using a contrast analysis (simple) about within a subject factor at a significance level of 0.05. RESULTS: Result of a repeated measures analysis regarding the surface microhardness of topical fluoride agents, there were significant differences at P-values of within and between the subject factor (P0.05). CONCLUSIONS: In this study, although there were significant differences at P-values of within and between the subject factor, there were no significant differences between the experiment groups on chemical pH cycling model in vitro, and it was limited to utilize this result in a clinical situation of the fluoride application.

Efficacy of Preoperative US Vascular Mapping for Arteriovenous Fistula in Patients with Hemodialysis

PURPOSE: The purpose of this study is to assess the efficacy of preoperative US vascular mapping to predict postoperative patency of the arteriovenous fistula for hemodialysis. MATERIALS AND METHODS: Sixty-six patients who underwent hemodialysis for end-stage renal failure (M: F=34:32, mean age, 58.8 years) were observed prospectively from January 2001 to April 2003. The patients were divided into two groups: the vascular mapping group and the control group. A comparative analysis of the re-operation rate between the two groups was determined by use of the chi-square rest, efficacy of preoperative US vascular mapping according to the type of surgery. A comparative analysis of the secondary patency after percutaneous transluminal angioplasty was determined by the use of Fischer exact test, and a comparative analysis of the diminution of patency during the follow-up periods was determined by the use of the Log-rank test. In the mapping group, the diameters of intraoperatively selected vessels were investigated and compared with the recommended diameter on preoperative US vascular mapping determined statistically by the use of Fisher's exact test. RESULTS: The preoperative US vascular mapping group had relatively lower re-operation rates (11.8%) than the control group (28.1%) (p=0.09). The preventive role of US vascular mapping is more effective in decreasing the re-operation rate for a native arteriorvenous fistula (7.4%) than for a synthetic arteriovenous graft (25.9%) (p=0.06). For patients that had an interventional procedure, the failure rate to obtain a secondary patency was smaller than in the mapping group (33.3%), compared with the control group (46.3%) (p=0.37). Patients in the mapping group had a higher patency than the control group patients for a native arteriovenous fistula (92.0%) and a synthetic arteriovenous graft (71.4%) at one year following surgery (p=0.10, p=0.79). The arteriovenous fistulas in the mapping group had a higher patency for both a native arteriovenous fistula (16.6%) and a synthetic arteriovenous graft (22.2%), which was statistically significant (p=0.01, p=0.03). CONCLUSION: Preoperative US vascular mapping is considered to be a useful technique for the preoperative evaluation of an arteriovenous fistula and to contribute to maintaining its postoperative patency and reducing the rate of repeated surgery.

Anatomic Variation of the Deep Venous System and its Relationship with Deep Vein Thrombosis Found on the Lower Extremity Venograms that were Obtained after Artificial Joint Replacements

PURPOSE: We wanted to evaluate the anatomic variations, the number of valves and the presence of deep vein thrombosis (DVT) on the lower extremity venograms obtained after artificial joint replacements, and we also wanted to determine the correlation of the incidence of DVT with the above-mentioned factors and the operation sites. MATERIALS AND METHODS: From January to June 2004, conventional ascending contrast venographies of the lower extremities were performed in 119 patients at 7-10 days after artificial joint replacement, and all the patients were asymptomatic. Total knee replacement was done for 152 cases and total hip replacement was done for 34 cases. On all the venographic images of 186 limbs, the anatomic variations were classified and the presence of DVT was evaluated; the number of valves in the superficial femoral vein(SFV) and calf veins was counted. The sites of DVT were classified as calf, thigh and pelvis. Statistically, chi square tests and Fischer's exact tests were performed to determine the correlation of the incidence of DVT with the anatomic variations, the numbers of valves and the operation sites. RESULTS: Theoretically, there are 9 types of anatomical variation in the deep vein system of the lower extremity that can be classified, but only 7 types were observed in this study. The most frequent type was the normal single SFV type and this was noted in 117 cases (63%), and the others were all variations (69 cases, 37%). There was a 22.2% incidence of DVT (69 cases) in the normal single SFV type and 26.4% (17 cases) in the other variations. No significant difference was noted in the incidences of DVT between the two groups. In addition, no significant statistical differences were noted for the incidences of DVT between the single or variant multiple veins in the SFV and the popliteal vein (PV) respectively, between the different groups with small or large numbers of valves in the thigh and calf, respectively, and also between the different operation sites of the hip or knee artificial joint replacements. The total number of asymptomatic DVT cases was 43 (23.1%) and DVT was found in the calf in 39 of these cases. CONCLUSION: Post-operative venograms of the lower extremity showed 7 types of anatomic variation in the deep venous system. The incidence of silent post-operative DVT was not influenced by anatomic variations of the deep vein system, whether there were a small or large number of valves and the operation sites for artificial joint replacement. The most frequent site of DVT after artificial joint replacement was the calf.

Development of VX-II Carcinoma Model in Rabbit Uterus: Evaluation with MR Imaging and Histopathology

PURPOSE: To develop a VX-II carcinoma model in the rabbit uterus and to describe the MR imaging findings of an experimentally induced VX-II uterine carcinoma along with the histopathologic findings. MATERIALS AND METHODS: 13 New Zealand rabbits were included in this study. Two pieces of tissue suspension (1 mm3x2) of VX-II carcinoma were loaded in an 18 gauge disposable needle and the tissue embedded in the wall of each horn of the rabbits' uterus. We obtained the MR images at 2 weeks in group A (n=5), or at 2 and 4 weeks in group B (n=8). T2-weighted images were obtained using an extremity coil. On MR imaging, we measured the signal intensity of the tumor and the uterine wall. We also measured the size and shape of the tumor and we compared this with the histopathologic results. RESULTS: On MR images obtained 2 weeks after inoculation, all the rabbit uteruses (group A and B, n=13) show a thick tubular wall, and the uteruses demonstrated a high signal intensity on T2-weighted images. The thickened uterine walls were measured as 3-10 mm (mean: 6.5 mm). Peritoneal nodules were observed in 3/13 rabbits (23%), the nodules measured 1.5-1.8x3.0 cm; uterine masses were observed in 3/13 rabbits (23%), and they measured 0.6-1.5x1.3-1.5 cm. On MR images obtained 4 weeks after the inoculations (group B, n=8), rabbit uteruses that had VX-II carcinoma show thick tubular wall in all cases (n=8, 100%) and round uterine masses (n=6, 75%). The thickened uterine walls measured 5-14 mm (mean 7.6 mm) and uterine masses measured 1.3-3.0x1.5-6.0 cm. All the rabbit uteruses having VX-II carcinoma showed high signal-to-noise ratios along the thickened uterine walls or masses on T2WI. On the histopathologic exam after sacrificing the rabbit, a few viable tumor cells were found because of necrosis in the inner portion of the uterine tumors, and abundant viable tumor cells were found at the periphery of the uterine tumors. CONCLUSION:We can develop an animal model with uterine tumor in rabbit uterus using VX-II carcinoma. Experimentally induced VX-II carcinomas in rabbit uterus demonstrated central necrosis, and MR imagings of experimentally induced uterine VX-II carcinomas were well correlated with the histopathology.

Equilibrium Phase MR Angiography Using New Blood Pool Contrasts: Experimental Study in Rabbits

PURPOSE: The purpose of this study was to evaluate the usefulness of three experimental blood pool contrast agents for equilibrium phase magnetic resonance angiography. MATERIALS AND METHODS: MR angiography was performed in 21 rabbits before and 1, 5, 10, 20 and 30 minutes and 24 hours after the injection of gadolinium-based blood pool contrast agents (Gadomer-17, Gadofluorine M,) and superparamagnetic iron oxide blood pool agent (Ferucarbotran). 3D TOF SPGR images of the thoracic and abdominal aorta (and involving the renal arteries) were obtained. The signal difference-to noise ratios (SDNRs) were measured over time in the aorta. These images were then compared to that of images with Gd-DTPA. RESULTS:MR angiography with the three blood pool agents yielded excellent visualization results of the rabbit abdominal aorta. At the same dose, the three agents provided a significant increase of the aorta-to-tissue SDNR in comparison with that achieved with the Gd-DTPA (a 250% increase for Gadomer-17, a 124% increase for Gadofluorine and a 88% increase for Ferucarbotran). The SDNRs using Ferucarbotran especially showed continuously increasing values to 30 minutes after the injection of contrast agent. CONCLUSION: The three blood pool agents were found to be very useful contrast agents for equilibrium phase MR angiography.

Clinical Evaluation of the Urinary Tract Infection and Long-term Indwelling Catheter / 대한비뇨기과학회지

One hundred fifty bacteriae isolated in significant numbers from 96 specimens of urine of the 45 in-patients with long-term indwelling catheter were evaluated from January, 1978 to July. 1979 and the following results were obtained; 1. In 20 patients (44.4%), positive urine culture was obtained within 10 days after indwelled catheter in the urinary tract and 97.9% of the patients revealed the positive urine culture within 20 days after that. 2. Of 150 bacterial strains isolated by cultures of the urine, 96% was gram-negative bacteria and 4% was gram-positive. Isolated organisms included klebsiella(27.4%), E.coli(23.3%). proteus(14.7%), pseudomonas(12.0%). coliform bacilli(10.0%). other gram-negative organism (8.6%), staphylococcus(2.7%) and streptococcus (l.3%) in order of frequency. 3. In 4 patients(8.9%), bacteremia was developed. Isolated organism from blood culture and those from urine culture were same. The mortality rate was 50%.