Sex differences in reference values of hip acetabular measurements using computed tomography in Japanese adults and the effect of aging on the measurement parameters.

BACKGROUND: It is very important to understand the acetabular morphology of the normal hip joint to assist in diagnosis and surgical planning of hip disorders. The purpose of the present study was to obtain gender-based reference values for the acetabular measurements of a normal hip using computed tomography data and investigate the effect of aging on the measurement values. METHODS: We measured acetabular parameters (center-edge angle, Sharp angle, vertical center anterior angle, acetabular anteversion) on computed tomography corrected for changing the obliquity, rotation, and tilt of the pelvis. We performed measurements in 245 patients (490 joints; 120 men [240 joints] and 125 women [250 joints]). The mean age was 64.7 ± 14.3 (31-88) years for men and 63.2 ± 15.2 (30-88) years for women. RESULTS: In men and women, the mean center-edge angle was 31.8° ± 6.4° and 30.6° ± 6.5°, the mean Sharp angle was 38.6° ± 3.2° and 40.6° ± 3.8°, the mean vertical center anterior angle was 44.3° ± 7.9° and 40.0° ± 8.5°, and the mean acetabular anteversion angle was 14.3° ± 5.2° and 18.8° ± 5.4°, respectively. All differences were statistically significant. The center-edge angle increased with age in women; however, such an effect was not observed in men. The other measurements showed a similar trend, such as larger vertical center anterior angle and smaller Sharp and acetabular anteversion angles, with aging in both men and women. CONCLUSIONS: We used computed tomography data to quantitatively assess the coverage and shape of the acetabulum in adult Japanese subjects and obtain the estimated reference ranges by gender. The results also proved that the measurements changed with aging in both sexes. These facts must be taken into account during the diagnosis of hip disease and planning of surgery.

[Analysis of the Environmental Factor of a Patient Falls in Department of Radiology-Proposal of Scientific Analysis Method in Patient Safety].

We analyzed 197 fall incidents in the questionnaire survey about the incident that occurred in Department of Radiology. In the past paper about the patient safety, there is no report that evaluated incident data directly. The purpose of this paper is to analyze the factor of the medical incidents using statistical technique scientifically. In this paper, we do not suggest concrete precaution. At first, we found the number of patients (each gender, modality, generation) in the five facilities of the coworker of one week. We found an incident rate from this patient total number, and we normalized data. As a result, we were able to do each risk evaluation because a risk ratio and relative risk degree was found. And, we were able to identify modality and the generation with the significant difference using the testing for differences in population rate. By our analyses, we revealed the chapter which must strengthen safety management.

[The Knowledge Gained from Questionnaire Survey of the Patients Fall in the Radiological Examinations -Focus on the Severity Due to Fall Accidents].

PURPOSE: The purpose of this study is to analyze the factors of patient's fall that causes serious injury in the radiological examinations. METHODS: We conducted a questionnaire survey on cases of medical accidents occurring in the radiological examination department in medical institutions. The number of responses to the questionnaire surveys was 372. Among them, 197 cases were related to fall. The incident influence classification divided into eight clusters (0, 0H, 1, 2, 3a, 3b, 4, 5) was divided into three clusters (tiny, moderate, serious injury) depending on severity. We analyzed the factors that cause serious injury. RESULTS: In the case of patient's fall, several factors have been found to cause serious injury. The factors were general radiography, standing position, outside working hours. CONCLUSION: All falls can cause serious injury. To reduce falls, it is important to analyze what kind of patient and in what situation tend to fall, and prevent falls in advance.

[The Actual Condition of Fall Accident and Suggestion of Improvement for Accident Prevention in the Department of Radiology].

We conducted a questionnaire survey (situation, patient factor, environmental factor, operator factor, degree of disability, countermeasure etc.) on cases that occurred up to the present to investigate the actual situation of the medical accidents that occur in the radiological examination department of medical institutions. There were 373 questionnaires collected. Among them, there were 197 cases of falls. In this study, we examined the age of patients who fell, the background of the accident, and factors. As for the accident, 11.7% of accidents with risk impact level 3b or higher occurred including the fatal accident. Of the accidents, 44.2% were foreseeable and 55.8% were unforeseeable. The most accident-prone age was elderly in their 60s to 80s. As the causative factor for the accident, the patient factor was the largest at 63.5%. We can prevent about 30% of the accident by improving the operator factor and the environmental factor which are parts other than patient factor. It is important for us to understand what kind of people tend to fall. Among foreseeable accidents, the causes of patient factors can be reduced.

[The Prevention of the Root Accident in the Department of Radiological Examination Room -Analysis of the Results of Questionnaire Survey about Medical Accident to Many Hospital].

PURPOSE: The purpose of this paper is to analyze the characteristics of incidents related to routes and drains that occur in the radiological examination room for the prevention of these incidents. METHODS: We conducted a questionnaire survey on incident cases that occurred in the radiological examination room. There were 373 responses, of which 76 responses were related to routes and drains. The question contents were the number of hospital beds, radiology department of occurrence, time of occurrence, patient's situation, method of visiting, years of experience of the radiological technologists, and countermeasures, and so on. Based on these answers to these questions, we analyzed which factors were involved in the occurrence of the incidents. RESULTS: Incidents related to routes and drains often occur when moving examination table or transferring the patients to the examination table using the slider. On the other hand, the years of experience of the radiological technologists hardly participated in the factor of these incidents. From these answers to questions, 75% of incidents might predictable, and these incidents could be prevented by improvement of human factors accounted for the majority rather than that of physical factors. CONCLUSION: The number of incidents related to routes and drains may reduce by that all staff involved in the radiological examination recognizing the characteristic of these incidents.

[Validity of the Signal-to-noise Ratio Measurement Method for MRI Using a Phase Image].

The most common methods to determine the signal-to-noise ratio (SNR) of magnetic resonance imaging (MRI) are based on the signal statistics in regions of interest (ROIs) in a magnitude image. For this, methods to calculate the ROI have still several discussions; we assumed SNR of a magnitude image could be estimated from standard deviation of a phase image (the phase method). The purpose of this study is to evaluate the validity of the phase method to determine the SNR. The simulation using digital phantom was carried out for evaluation of the effect to measure SNR; fluctuation in the phase image and SNR of the magnitude image. The phantom study was also performed for evaluation of the validity of estimation using the phase method in comparison with the conventional method (the identical ROI method and the subtraction method). The result of the simulation showed that SNR of magnitude image is larger than 4 for the SNR measurement using the phase method and this results reliable. The influence of fluctuation of the phase image should be eliminated for practical purposes. In the phantom study, phase method showed similar results compared to conventional methods in condition with elimination of the fluctuation of the phase image. Though there was a difference in the results of the phase method and the subtraction method according to the position of the ROI, the error was less than 4%. In this study, the method using the phase image to determine the SNR was identified as valuable.

[Analysis of accidents for magnetically induced displacement of the large ferromagnetic material in magnetic resonance systems].

To improve magnetic resonance (MR) safety, we surveyed the accidents caused by large ferromagnetic materials brought into MR systems accidentally. We sent a questionnaire to 700 Japanese medical institutions and received 405 valid responses (58%). A total of 97 accidents in 77 institutions were observed and we analyzed them regarding incidental rate, the detail situation and environmental factors. The mean accident rate of each institute was 0.7/100,000 examinations, which was widely distributed (0-25.6/100,000) depending on the institute. In this survey, relatively small institutes with less than 500 beds tend to have these accidents more frequently (p<0.01). The institutes in which daily MR examination counts are more than 10 patients have fewer accidents than those with less than 10 daily examinations. The institutes with 6-10 MR examinations daily have significantly more accidents than that with more than 10 daily MR examinations (p<0.01). The main mental factors of the accidents were considered to be "prejudice" and "carelessness" but some advocate "ignorance." Though we could not find significant reduction in the institutes that have lectures and training for MR safety, we should continue lectures and training for MR safety to reduce accidents due to "ignorance."

Can magnetic resonance imaging after cranioplasty using titanium mesh detect brain tumors?

This study determined the dependence of the concentration and position of contrast-enhanced tumors on the radio frequency (RF)-shielding effect of titanium mesh using the contrast-to-noise ratio (CNR) in magnetic resonance imaging (MRI). A phantom was constructed by filling a plastic container with manganese chloride tetrahydrate and agar. Four cellophane cylindrical containers were arranged from the end of the plastic container, and the brain tumor model was filled with gadobutrol diluted with NaCl, with molarity values of 0.2-1.0 mmol/L. The titanium mesh board was set on the left side of the phantom. Images were acquired using a 1.5-T MRI as well as two-dimensional spin-echo (2D SE) and three-dimensional fast spoiled gradient echo (3D FSPGR) sequences. CNR was calculated using the signal intensity values of the tumor model, surrounding area of the brain model, and background noise. Furthermore, the fractional change in CNR was calculated using values of CNR with and without the mesh. Moreover, a profile of CNR was created. The fractional change in CNR decreased at the brain tumor positions present near the mesh and at a contrast medium concentration of approximately ≤ 0.5 mmol/L in 2D SE and ≤ 0.25 mmol/L in 3D FSPGR. According to the CNR profiles, directly under the mesh, almost all contrast concentrations in 2D SE was unrecognizable; however, at a concentration of ≥ 0.5 mmol/L in 3D FSPGR was recognizable.

[Feasibility Study of the Prediction of Radiologist's Instructions with the Bi-LSTM Model Trained with Descriptions of MR Imaging Order-statement].

PURPOSE: Magnetic resonance (MR) images provide essential diagnostic information; however, it is also a very burdensome examination for patients. At our hospital, radiologists make imaging instructions for all MR examination orders, but this is a time-consuming task. If a natural language processing model can predict the imaging instructions, it will be possible to reduce the burden on radiologists and the instruction quality can be assured. The purpose of this study was to investigate the feasibility of using natural language processing to predict MR imaging instructions with the aim of assisting radiologists. METHODS: Considering the uniqueness of the MR imaging protocols at each facility and the particularity of the test order text, we considered that the use of large datasets and pre-training models would be unsuitable. We focused on LSTM, which has been used for natural language processing, and built a 4-layer bi-LSTM model in combination with our own morphological preprocessing to predict MR imaging instructions. RESULTS: The proposed method achieved macro-average precision, recall, and F1-score of 70.6%, 69.5%, and 68.9%, respectively. Compared to the previous studies, the proposed method achieved satisfactory performance in the natural language analysis task for Japanese. It is considered that the proposed method improved the prediction accuracy of the minority class through direct and indirect effects of vocabulary reduction, optimization, and similarity learning. CONCLUSION: It is suggested that the proposed method is effective and that the prediction of MR imaging instructions using natural language analysis in combination with the proposed method is feasible.

Pain-Related Abnormal Neuronal Synchronization of the Nucleus Accumbens in Parkinson's Disease.

Patients with Parkinson's disease (PD) often experience pain, which fluctuates in "on" and "off" states, but the underlying mechanism is unclear. The nucleus accumbens (NAc) is a central component of the mesolimbic dopaminergic pathway involved in pain processing. We conducted resting-state functional magnetic resonance imaging (rsfMRI) analysis to explore the relationship between the neuronal synchronization of NAc with pain-related brain regions and pain intensity in "on" and "off" states. We assessed 23 patients with sporadic PD based on rsfMRI and pain intensity using the revised Short-Form McGill Pain Questionnaire. Patients with PD displayed higher pain intensity scores in the "off" state than in the "on" state. The pain intensity in the "off" state was substantially correlated with the functional connectivity (FC) between the NAc and primary motor/sensory cortices and contralateral NAc. Changes in pain intensity from the "on" to "off" state displayed correlations with those between the right (rNA) and left NAc (lNAc) and the right precentral gyrus (rPreCG) /right insular cortex (rIC) from the "off" to "on" state. Aberrant bilateral NAc and rNAc-rPreCG/rIC FC in the "off" state were closely related to pain symptoms developed from the "on" to "off" states. These results suggest that the NAc in the mesolimbic pathway is related to pain in PD and may help understand the mechanism of pain development in patients with PD.

Echo-planar imaging is superior to fast spin-echo diffusion-weighted imaging for cranioplasty using titanium mesh in brain magnetic resonance imaging: a phantom study.

This study aimed to compare the radiofrequency (RF) shielding effects of titanium mesh of echo-planar imaging (EPI) versus fast spin-echo (FSE) diffusion-weighted imaging (DWI) to establish a suitable sequence for patients who undergo cranioplasty and for whom titanium mesh was used in brain magnetic resonance imaging (MRI). A 1.5-T MRI scanner with clinical setting sequences was used. A phantom for the examination constructed using a sucrose solution in a plastic container was used to compare the signal attenuation (SA) ratio, area of RF shielding effect (Area), normalized absolute average deviation (NAAD), and apparent diffusion coefficient (ADC) between EPI and FSE-DWI. EPI provided significantly better SA ratio, Area, and NAAD (P < 0.01). When the number of slices increased, the RF shielding became more negative. There was no significant difference in the ADC. Regardless of the k-trajectory, EPI-DWI had a lower RF shielding effect than FSE-DWI in patients undergoing cranioplasty.

Three-dimensional Gradient-echo is Effective in Suppressing Radiofrequency Shielding by a Titanium Mesh.

PURPOSE: To determine which sequence for frequently used general contrast-enhanced brain MRI shows the least radiofrequency shielding effect of a titanium mesh in cranioplasty using a phantom. METHODS: A 1.5T MRI scanner was used. Frequently used general 2D and 3D spin-echo sequences (SE) and T1 spoiled gradient echo sequences (GRE) used for MRI in clinical settings were adopted in this study. A titanium mesh was placed above a cubic phantom containing manganese chloride tetrahydrate and sodium chloride. The signal attenuation ratio and normalized absolute average deviation (NAAD) were calculated. Moreover, the flip angle (FA) dependency in SE and area of excitation dependency in 3D sequences were analyzed using NAAD. RESULTS: The signal attenuation ratio at the position nearest to the titanium mesh for 2D SE was 71.8% larger than that at the position nearest to the titanium mesh for 3D GRE. With regard to NAAD, 3D GRE showed the highest values among the sequences. When FA was increased, radiofrequency shielding effect was improved. There were no significant differences between the narrow and wide area of excitation. 3D GRE showed the least radiofrequency shielding effect, and it was considered as the optimal sequence for MRI in the presence of a titanium mesh. CONCLUSION: 3D GRE shows the least radiofrequency shielding effect of a titanium mesh after cranioplasty among frequently used general sequences for contrast-enhanced brain MRI.

Brain surface motion imaging to predict adhesions between meningiomas and the brain surface.

INTRODUCTION: "Brain surface motion imaging" (BSMI) is the subtraction of pulse-gated, 3D, heavily T2-weighted image of two different phases of cerebrospinal fluid (CSF) pulsation, which enables the assessment of the dynamics of brain surface pulsatile motion. The purpose of this study was to evaluate the feasibility of this imaging method for providing presurgical information about adhesions between meningiomas and the brain surface. METHODS: Eighteen cases with surgically resected meningioma in whom BSMI was presurgically obtained were studied. BSMI consisted of two sets of pulse-gated, 3D, heavily T2-weighted, fast spin echo scans. Images of the systolic phase and the diastolic phase were obtained, and subtraction was performed with 3D motion correction. We analyzed the presence of band-like texture surrounding the tumor and judged the degree of motion discrepancy as "total," "partial," or "none." The correlation between BSMI and surgical findings was evaluated. For cases with partial adhesions, agreements in the locations of the adhesions were also evaluated. RESULTS: On presurgical BSMI, no motion discrepancy was seen in eight cases, partial in six cases, and total in four cases. These presurgical predictions about adhesions and surgical findings agreed in 13 cases (72.2%). The locations of adhesions agreed in five of six cases with partial adhesions. CONCLUSION: In the current study, BSMI could predict brain and meningioma adhesions correctly in 72.2% of cases, and adhesion location could also be predicted. This imaging method appears to provide presurgical information about brain/meningioma adhesions.

[The effect of the surroundings to the apparent diffusion coefficient on diffusion weighted imaging].

Diffusion weighted imaging (DWI) is now widely used in magnetic resonance (MR) imaging of the head and body. Moreover, the Apparent diffusion coefficient (ADC) value is often used for the differential diagnosis of the tumor. However, the effect of the surroundings on the ADC value has not been reported. In this study, we used the phantom completely sealed up to measure the change in the ADC value depending on the surroundings material. The results showed that the ADC value decreased according to the density of superparamagnetic iron oxide (SPIO) in the surroundings. Clinically, hemorrhage or iron deposit around the tumor may affect the ADC value of the tumor and result in under-estimation.

Radiofrequency-shielding Effect of a Titanium Mesh Implanted for Cranioplasty.

PURPOSE: After cranioplasty with a titanium mesh, radiofrequency (RF)-shielding images appear during magnetic resonance (MR) imaging. To clarify their influence, we evaluated the effect of mesh position, phase-encoding direction, and type of coil employed. MATERIALS AND METHODS: On a 1.5-tesla MR imager, we placed a titanium mesh board (100 × 100 × 0.8 mm) on the surface of a cubic phantom to mimic a human brain and used a quadrature coil and an 8-channel neurovascular coil to measure nonuniformity, signal decay ratio, and the B1 map. RESULTS: Nonuniformity was 6.7 times higher at the quadrature head coil and 1.6 times higher at the neurovascular coil when the mesh was on the phantom's right side or anterior to it than when it was on its superior end or absent. The profile of the signal decay ratio increased by 1.9% mm(-1) from 0 to 40 mm from the mesh side to the base value at the quadrature head coil when the mesh was on the phantom's right side and 0.9% mm(-1) from 0 to 80 mm at the neurovascular coil when the mesh was on the phantom's right side or anterior to it. The quadrature head coil showed greater incline of the profile when the mesh was on the right in coronal and axial views and no notable change in the profile in coronal and sagittal views when the mesh was on the superior end. In the B1 map, the flip angle was lower when the mesh was nearer. CONCLUSION: The response to the RF-shielding effect from a titanium mesh depends on the location of the mesh and the RF coil used but not on the phase-encoding direction.

[An investigative report concerning safety and management in the magnetic resonance environment: there are more accidents than expected].

Using a questionnaire, we surveyed 2,500 facilities in Japan to clarify medical accidents concerning the magnetic resonance device and its environment. Data derived from 1,319 valid responses (52.8%), allowed us to analyze the situation of (or the reason for) the occurrence of the accidents and their environmental factors. Five hundred and nine facilities (39% of all facilities) had the experience of magnetically induced displacement of the large ferromagnetic material. Intravenous (I.V.) drip stands were involved the largest number of them: 31% (228 cases). Oxygen bottles had the second largest number of incidents: 20%. There were also many incidents involving various materials brought in by non-medical staff (e.g. stepladder for construction). About 20% of the accidents occurred outside of working hours. Patients in 12% of the facilities (154 facilities) experienced burns. In 39 of the cases, burns were received to the inside of the thighs. In 38 of the cases, patients received burns from an electrical cable touching the skin. There were also frequent incidents of burning regarding the boa. We received reports of burns and pain from the halo vest even though it's required to be worn for MR safety. Regarding incidents of contraindications, 280 patients with pacemakers were brought into the magnetic resonance (MR) inspection room. Twelve percent of the facilities experienced natural quench. Lack of training for the staff who introduce and operate high magnetic field devices are considered involving frequently occurring accidents of attractions and burns at hospitals with over 500 beds caused by carrying in materials.