• Journal of Radiation Protection and Research
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• v.38 no.3
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• pp.157-165
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• 2013

To determine the factors affecting the external radiation dose rates of patients undergoing PET-MRI examinations and to assess the trends of these differences, we measured the changes in the dose rates of $^{18}F$-FDG during a set period of time for each body region. Consistent with theoretical predictions, the dose rate decreased over time in patients undergoing PET-MRI examinations. Furthermore, immediately after the $^{18}F$-FDG injection, the dose rate in the chest region was the highest, followed by the abdominal region, the head region, and the foot region. The dose rate decreased drastically as time passed, by 2.47-fold, from $339.23{\pm}74.70mSv\;h^{-1}$ ($6.73{\pm}5.79$ min) at the time point immediately after the $^{18}F$-FDG injection to $102.71{\pm}26.17mSv\;h^{-1}$ ($136.11{\pm}25.64$ min) after the examination. In the foot region, there were no significant changes over time, from $32.05{\pm}20.23mSv\;h^{-1}$ ($6.73{\pm}5.79$ min) at the time point immediately after the $^{18}F$-FDG injection, to $23.89{\pm}9.14mSv\;h^{-1}$ ($136.11{\pm}25.64$ min) after the examination. The dose rate is dependent on the individual characteristics of the patient, and differed depending on the body region and time point. However, the dose rates were higher in patients who had a lower body weight, shorter stature, fewer urinations, lower fluid intake, and history of diabetes mellitus. To decrease radiation exposure, it is difficult or impossible to change factors inherent to the patient, such as sex, age, height, body weight, obesity, and history of diabetes mellitus. However, factors which can be changed, such as the $^{18}F$-FDG dose, fasting time, fluid intake, number of urinations, and contrast agent dose can be controlled to minimize the external radiation exposure of the patient.

• Journal of radiological science and technology
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• v.40 no.1
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• pp.19-25
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• 2017

The aim of this study was to evaluate Magnetic Resonance Imaging safety by measuring the translational attraction, torque and susceptibility artifact for Bone-Anchored Hearing Aid (BAHA) implant at 1.5 T and 3.0 T MRI by standard criteria. In vitro assessment tools were made of acrylic-resin by American Society for Testing and Materials (ASTM) F2052-06 and F2119-07 standard. Translational attraction of BAHA implant was measured by the maximum deflection angle at 96 cm position, where the magnetically induced deflection was the greatest. The torque was assessed by the qualitative criteria of evaluating the alignment and rotation pattern, when the BAHA implant was positioned on a line with $45^{\circ}$ intervals inside the circular container in the center of the bore. The susceptibility artifact images were obtained using the hanged test tool, which was filled with $CuSO_4$ solution. And then the artifact size was measured using Susceptibility A rtifact Measurement (SA M) software. In results, the translational attraction was 0 mm at both 1.5 T and 3.0 T and the torque was 0(no torque) at 1.5 T, and +1(mild torque) at 3.0 T. The size of susceptibility artifacts was between 13.20 mm and 38.91 mm. Therefore, The BAHA implant was safe for the patient in clinical MR environment.

• Journal of IKEEE
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• v.12 no.3
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• pp.158-166
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• 2008

Medical ultrasound has benefits in mobility and safety than any other medical techniques such as X-ray, CT and MRI but has speckle noise which decrease the ability of an observer to distinguish the fine details in diagnostic examination. But simple removing of speckle often causes losing boundary information. Then, in this paper, we presented a novel neuro-fuzzy method which could remove speckle efficiently without loss of boundary information. Proposed method consists of image clustering by fuzzy algorithm and image processingby neural networks which was learned by back propagation. From the experiments for simulation image and real ultrasound image, we could verify the proposed method.

• Journal of Korean Neurosurgical Society
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• v.53 no.6
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• pp.323-330
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• 2013

Objective : To develop a simple, reproducible model of disc degeneration in rabbits through percutaneous annular puncture and to confirm the degree of degeneration over time. Methods : Fifteen New Zealand white rabbits (4 to 5 months old and weighing approximately 3 to 3.5 kg each) underwent annular puncture of the L2-L3, L3-L4, and L4-L5 discs. Rabbits were sacrificed at 4, 8, or 20 weeks after puncture. For a longitudinal study to assess changes in disc height over time, serial X-rays were performed at 0, 2, 4, 8, and 20 weeks for rabbits in the 20-week group. Upon sacrifice, the whole spinal column and discs were extracted and analyzed with magnetic resonance imaging (MRI), real time reverse transcriptase-polymerase chain reaction, and histological staining. Results : The X-rays showed a slow, progressive decrease in disc height over time. Significant disc space narrowing compared to preoperative disc height was observed during the time period (p<0.001). The MRI grade, aggrecan, and matrix metalloprotease-13 mRNA expression and hematoxylin and eosin/safranin O/anti-collagen II staining were consistently indicative of degeneration, supporting the results of the X-ray data. Conclusion : Percutaneous annular puncture resulted in slow, reproducible disc degeneration that was confirmed by radiology, biochemistry, and histology. This in vivo model can be used to study and evaluate the safety and efficacy of biologic treatments for degenerative disc disease.

• Journal of Korean Foot and Ankle Society
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• v.20 no.3
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• pp.112-115
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• 2016

Purpose: We aimed to investigate the safety zone for Achilles tendon insertion in the posterior aspect of the calcaneus via the use of magnetic resonance imaging (MRI) when planning for insertional Achilles tendinopathy. Materials and Methods: This study included 95 patients. The MRI of midsagittal plane of the ankle joint was used to measure the proximal and distal insertion point for the Achilles tendon in the posterior aspect of the calcaneus. Patients were divided into three groups according to the proportion of the distal insertion point out of the entire calcaneal length: the proximal, middle, and distal insertion groups. Results: The mean proximal and distal insertion points for the Achilles tendon were measured as 1.05 cm (0~2.11 cm) and 2.36 cm (1.60~2.93 cm), respectively. When the posterior aspect of the calcaneus was used as the reference plane, none of the patients was in the proximal insertion group, while 75 and 20 patients were in the middle and distal insertion groups, respectively. The insertion portion was longer in the distal insertion group ($1.47{\pm}0.25cm$) than in the middle insertion group ($1.27{\pm}0.35cm$). Statistically significant differences with respect to the length of the insertion portion were observed between the two groups (p=0.008). Conclusion: Removal of more than 1 cm below the superior margin of the posterior calcaneus may be dangerous. An MRI study on the Achilles tendon of patients without hindfoot deformity or tendinopathy revealed various insertional characteristics. Preoperative MRI evaluation is safer than relying solely on the simple radiological assessment when planning for insertional Achilles tendinopathy.

• Proceedings of the Safety Management and Science Conference
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• 2010.11a
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• pp.103-112
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• 2010

This study was done to provide basic data on the safety of professionals in medical imaging system by measuring the electromagnetic waves generated in the medical imaging system being used in medical organization. The studied medical imaging systems were general X-ray system, computed tomography(CT), ultrasonographic system, magnetic resonance imaging(MRI), PET-CT and fluoroscopic system, and through these devices, electric field and magnetic field were measured and analyzed. As a result of the analysis, the measured values classified by the medical organizations were not much significant, but in the measurement by the medical imaging systems, there were high hazard elements in the sequential order of electric field PET-CT($17.7{\pm}22.9$)v/m, CT($10.3{\pm}8.7$)v/m, general X-ray system ($8.8{\pm}8.8$)v/m, magnetic field general X-ray system($5.06{\pm}8.26$)mG, CT($2.71{\pm}4.53$)mG and PET-CT($0.74{\pm}0.34$)mG, the systems that adopted X-ray as main ray source, and the more aged the medical imaging systems, the greater the effects of electro-magnetic waves($10.6{\pm}15.93v/m$ for 5 years or more, $6.14{\pm}5.60v/m$ for 5 years or less). The effects of electromagnetic waves on medical imaging systems or facilities were not much when the notification of ministry of knowledge economy is considered, but in the overall perspective considering all the equipments and facility of the medical organization, such effects were significant. It is determined that sustainable safety managements of electric field and magnetic field must be done during process from medical imaging system installation to maintenance to rule out such factors.

• Journal of the Korea Safety Management & Science
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• v.12 no.4
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• pp.67-72
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• 2010

This study was done to provide basic data on the safety of professionals in medical imaging system by measuring the electromagnetic waves generated in the medical imaging system being used in medical organization. The studied medical imaging systems were general X-ray system, computed tomography(CT), ultrasonographic(USG) system, magnetic resonance imaging(MRI), PET-CT and fluoroscopic(R/F) system, and through these devices, electric field and magnetic field were measured and analyzed. As a result of the analysis, the measured values classified by the medical organizations were not much significant, but in the measurement by the medical imaging systems, there were high hazard elements in the sequential order of electric field PET-CT($17.7{\pm}22.9$)v/m, CT($10.3{\pm}8.7$)v/m, general X-ray system($8.8{\pm}8.8$)v/m, magnetic field general X-ray system($5.06{\pm}8.26$)mG, CT($2.71{\pm}4.53$)mG and PET-CT($0.74{\pm}0.34$)mG, the systems that adopted X-ray as main ray source, and the more aged the medical imaging systems, the greater the effects of electro-magnetic waves($10.6{\pm}15.93v/m$ for 5 years or more, $6.14{\pm}5.60v/m$ for 5 years or less). The effects of electromagnetic waves on medical imaging systems or facilities were not much when the notification of ministry of knowledge economy is considered, but in the overall perspective considering all the equipments and facility of the medical organization, such effects were significant. It is determined that sustainable safety managements of electric field and magnetic field must be done during process from medical imaging system installation to maintenance to rule out such factors.

• Journal of Korean Neurosurgical Society
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• v.48 no.4
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• pp.335-341
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• 2010

Objective : Anterior cervical corpectomy with fusion (ACF) or laminoplasty may be associated with substantial number of complications for treating multilevel cervical ossification of the posterior longitudinal ligament (OPLL) with significant cord compression. For more safe decompression and stabilization in multilevel cervical OPLL with prominent cord compression, we propose circumferential cervical surgery (selective ACF and laminoplasty) based on our favorable experience. Methods : Twelve patients with cervical myelopathy underwent circumferential cervical surgery and all patients showed multilevel OPLL with Signal change of the spinal cord on magnetic resonance imaging (MRI). A retrospective review of clinical, radiological. and surgical data was conducted. Results : There were 9 men and 3 women with mean age of 56.7 years and a mean follow up period of 15.6 months. The average corpectomy level was 1.16 and laminoplasty level was 4.58. The average Japanese Orthopedic Association score for recovery was 5.1 points and good clinical results were obtained in 11 patients (92%) (p < 0.05). The average space available for the cord improved from 58.2% to 87.9% and the average Cobb's angle changed from 7.63 to 12.27 at 6 months after operation without failure of fusion (p < 0.05). Average operation time was 8.36 hours, with an estimated blood loss of 760 mL and duration of bed rest of 2.0 days. There were no incidences of significant surgical complications, including wound infection. Conclusion : Although the current study examined a small sample with relatively short-term follow-up periods, our study results demonstrate that circumferential cervical surgery is considered favorable for safety and effectiveness in multilevel OPLL with prominent cord compression.

• Journal of Korean Neurosurgical Society
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• v.51 no.1
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• pp.8-13
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• 2012

Objective : This is prospective study of clinical outcomes of percutaneous plasma disc coagulation Therapy (PDCT) in patients with herniated lumbar disc disease (HLD) to evaluate the safety and efficacy in its clinical application and usefulness as a reliable alternative to microscopic discectomy. Methods : Forty-six patients were enrolled in this study from April 2006 to June 2010. All patients had one-level HLD. Disc degeneration was graded on routine T2-weighted magnetic resonance Image (MRI) using the Pfirrmann's grading system and all index levels were grade 3 and grade 4. Indications for surgery were radiculopathy caused by disc protrusion with soft consistency. MRI was done at one month after the procedure in all patients to check post-PDCT change. The clinical outcomes were evaluated using Visual Analog Scales (VAS) score and MacNab's criteria. Results : This study was approved by the Institutional Review Board of our institution. The age of the study population ranged from 16 to 59 years with a mean age of 37.2 years. There were 29 males and 17 females in this study. The mean period of clinical follow-up was 21 months. The average preoperative VAS score for radiculopathy was $7.4{\pm}1.4$, while the final follow-up VAS score was $1.4{\pm}0.7$ (p<0.001). In MacNab's criteria, 41 patients (89.1%) had achieved favorable improvement (excellent and good) until later follow-up. There were one patient from infection and two patients who needed to convert to open discectomy. Conclusion : PDCT is a safe and efficient treatment modality in a selective patient with HLD.

• Korean Journal of Radiology
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• v.25 no.3
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• pp.257-266
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• 2024

Objective: To investigate molecular and functional consequences of additional exposures to iodine- or gadolinium-based contrast agents within 24 hours from the initial intravenous administration of iodine-based contrast agents through an animal study. Materials and Methods: Fifty-six Sprague-Dawley male rats were equally divided into eight groups: negative control, positive control (PC) with single-dose administration of CT contrast agent, and additional administration of either CT or MR contrast agents 2, 4, or 24 hours from initial CT contrast agent injection. A 12 µL/g of iodinated contrast agent or a 0.47 µL/g of gadolinium-based contrast agent were injected into the tail vein. Serum levels of blood urea nitrogen, creatinine, cystatin C (Cys C), and malondialdehyde (MDA) were measured. mRNA and protein levels of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated. Results: Levels of serum creatinine (SCr) were significantly higher in repeated CT contrast agent injection groups than in PC (0.21 ± 0.02 mg/dL for PC; 0.40 ± 0.02, 0.34 ± 0.03, and 0.41 ± 0.10 mg/dL for 2-, 4-, and 24-hour interval groups, respectively; P < 0.001). There was no significant difference in the average Cys C and MDA levels between PC and repeated CT contrast agent injection groups (Cys C, P = 0.256-0.362; MDA, P > 0.99). Additional doses of MR contrast agent did not make significant changes compared to PC in SCr (P > 0.99), Cys C (P = 0.262), and MDA (P = 0.139-0.771) levels. mRNA and protein levels of KIM-1 and NGAL were not significantly different among additional CT or MR contrast agent groups (P > 0.05). Conclusion: A sufficient time interval, probably more than 24 hours, between repeated contrast-enhanced CT examinations may be necessary to avoid deterioration in renal function. However, conducting contrast-enhanced MRI on the same day as contrast-enhanced CT may not induce clinically significant kidney injury.