[Risk Communication of Radiation Exposure for Diagnosis: A Questionnaire Survey].

PURPOSE: We investigated how a radiologic technologist explains to a patient about the risk of radiation exposure involved by the radiological examination. METHODS: In this institutional review board-approved, cross-sectional study, an online questionnaire link was emailed to 650 radiological technologists who are members of the National Hospital Kanto Koshinetsu Radiological Technologist Association. The questions to survey risk communication included the ideal and reality explanation for radiation exposure to patients, the respondent's educational background, and years of experience. Statistical analysis was performed using the Kruskal-Wallis test and Bonferroni correction as a multiple comparison test. RESULTS: Among the 650 radiological technologists, 245 (37.7%) completed the online questionnaire. The most common response was to compare and convey the doses of radiation during examination and background radiation when asked by a patient about risk. In the cross-analysis, the Kruskal-Wallis test showed no significant difference in what was explained according to educational background. According to years of experience, a significant difference in the content was found about explanation of the risk to patients. CONCLUSIONS: We clarified the actual condition of risk communication related to the exposure in radiological examinations. In the future, development of risk communication is expected by improving the knowledge and information of "risk" and giving explanations requested by patients.

Association between Brain and Plasma Glutamine Levels in Healthy Young Subjects Investigated by MRS and LC/MS.

Both glutamine (Gln) and glutamate (Glu) are known to exist in plasma and brain. However, despite the assumed relationship between brain and plasma, no studies have clarified the association between them. Proton magnetic resonance spectroscopy (MRS) was sequentially performed twice, with a 60-min interval, on 10 males and 10 females using a 3T scanner. Blood samples for liquid chromatography-mass spectrometry (LC/MS) to measure Gln and Glu concentrations in plasma were collected during the time interval between the two MRS sessions. MRS voxels of interest were localized at the posterior cingulate cortex (PCC) and cerebellum (Cbll) and measured by the SPECIAL sequence. Spearman's correlation coefficient was used to examine the association between brain and plasma metabolites. The Gln concentrations in PCC (mean of two measurements) were positively correlated with Gln concentrations in plasma (p < 0.01, r = 0.72). However, the Glu concentrations in the two regions were not correlated with those in plasma. Consideration of the different dynamics of Gln and Glu between plasma and brain is crucial when addressing the pathomechanism and therapeutic strategies for brain disorders such as Alzheimer's disease and hepatic encephalopathy.

[Consideration on SNR in Synthetic MRI].

Synthetic magnetic resonance imaging (MRI) can create different contrast weighted images by quantifying the T1, T2, and proton density values of the subjects from a single series of scan data. It has not been clarified how the signal to noise ratio (SNR) of the synthesized image varies depending on imaging parameters. We investigated the change of SNR in synthesized MR images by the experiment using self-made phantom. The SNR ratio of synthesized image by synthetic MRI showed the same tendency as the theoretical values due to parameter change in Ny, Nx, slice thickness, number of excitations. However, as for BW, the SNR ratio tended to be different from the theoretical values in some cases. In addition, it was suggested that the SNR of the composite image has relevance to the quantitative accuracy of the T1, T2, and proton density values. We thought that this is due to the image acquisition process by synthetic MRI.

Near-Infrared-Responsive Peptide that Targets Collagen Fibrils to Induce Cytotoxicity.

A novel conjugate, PHG10 dye, was synthesized using a collagen peptide and a near-infrared (NIR)-responsive dye to achieve targeted cytotoxicity. The collagen peptide motif, -(Pro-Hyp-Gly)10 - (PHG10), was incorporated for targeting collagen fibrils that are excessively produced by activated fibroblasts around tumor cells. PHG10 dye was purified by HPLC and identified by MALDI-MS. The phototoxicity and cytotoxicity of PHG10 dye were examined using human glioma cells (HGCs). Fluorescent images indicated that PHG10 dye preferably assembled to collagen-coated HGCs compared with noncoated HGCs. Under irradiation with NIR light, effective cytotoxicity was observed on collagen-coated HGCs within 20 min. Because phototoxicity and cytotoxicity are dependent on the assembled amount of PHG10 dye, the targeting of collagen fibrils by the collagen peptide motif PHG10 is assured.

25 Years of Contrast-Enhanced MRI: Developments, Current Challenges and Future Perspectives.

UNLABELLED: In 1988, the first contrast agent specifically designed for magnetic resonance imaging (MRI), gadopentetate dimeglumine (Magnevist(®)), became available for clinical use. Since then, a plethora of studies have investigated the potential of MRI contrast agents for diagnostic imaging across the body, including the central nervous system, heart and circulation, breast, lungs, the gastrointestinal, genitourinary, musculoskeletal and lymphatic systems, and even the skin. Today, after 25 years of contrast-enhanced (CE-) MRI in clinical practice, the utility of this diagnostic imaging modality has expanded beyond initial expectations to become an essential tool for disease diagnosis and management worldwide. CE-MRI continues to evolve, with new techniques, advanced technologies, and novel contrast agents bringing exciting opportunities for more sensitive, targeted imaging and improved patient management, along with associated clinical challenges. This review aims to provide an overview on the history of MRI and contrast media development, to highlight certain key advances in the clinical development of CE-MRI, to outline current technical trends and clinical challenges, and to suggest some important future perspectives. FUNDING: Bayer HealthCare.

Validation of a Metal Artifact Reduction Algorithm Using 1D Linear Interpolation for Cone Beam CT after Endovascular Coiling Therapy for Cerebral Aneurysms.

This study aimed to evaluate the effect of a metal artifact reduction (MAR) algorithm using 1D linear interpolation on cone-beam CT (CBCT). We performed phantom and clinical qualitative studies with and without MAR application using 1D linear interpolation. In the phantom study, the standard deviation (SD) was estimated from the images obtained from the water phantom in which a metal coil was placed at the center, and observed the changes in the SDs before and after MAR application. In the clinical qualitative study, the clinical images after endovascular treatment (EVT) for cerebral aneurysms were visually evaluated before and after MAR application. In the phantom study, the SDs after MAR application decreased by 56 to 35% compared with that before MAR application. In the clinical qualitative study, the artifacts from the metal coil decreased or increased depending on locations, and the contrasts of gray matter and white matter were attenuated when MAR was applied. In conclusion, the metal artifact decreases when MAR using 1D linear interpolation is applied to cerebral CBCT. However, another artifacts increase or soft tissue contrast is changed in some cases. MAR largely contributes to the reduction of streaking artifacts, whereas it may induce cerebral parenchyma at distant metal body or quality deterioration of the image not including the metal body. This should be taken into account in the diagnosis of secondary hemorrhage or infarction.

Safety of gadopentetate dimeglumine after 120 million administrations over 25 years of clinical use.

PURPOSE: We evaluated the safety of gadopentetate dimeglumine (Gd-DTPA), the first contrast agent for magnetic resonance imaging, using pharmacovigilance data for spontaneously reported adverse events (AEs) after 120 million cumulative administrations worldwide. METHODS: We analyzed spontaneously reported AEs for Gd-DTPA for pre-specified time periods between 1988 and 2011. RESULTS: Since the market introduction of Gd-DTPA in 1988, its global utilization reached 120 million cumulative administrations in 2011, more than 80% of which was by the USA, countries in the European Union (EU), and Japan. The global AE reporting rate was 21.2 in 100,000 administrations in 1988 and 14.4 in 100,000 administrations by 2011. Regional differences included higher reporting rates in the USA and Japan, and reporting rates lower than global rates in the EU. The reported rate of global serious AEs changed from 1.4 in 100,000 administrations in 1988 to 4.0 in 100,000 administrations in 2011. The highest number of reports of nephrogenic systemic fibrosis (NSF) was received from 2006 to 2008. Since 2009, no report of a current onset of NSF has been received. The reduced report rate of NSF may be due to increased awareness about the use of gadolinium-based contrast agents (GBCAs). CONCLUSION: After more than 120 million cumulative administrations, Gd-DTPA is a widely used GBCA that shows a consistently low and stable incidence of AEs.

[Effect of Kiken-Yochi training (KYT) induction on patient safety at the department of radiological technology].

PURPOSE: In this report, we evaluated whether radiological technologists' (RTs') awareness of patient safety would improve and what kind of effects would be seen at the department of radiological technology by introducing KYT [K: kiken (hazard), Y: yochi (prediction), T: (training)]. METHODS: KYT was carried out by ten RTs based on a KYT sheet for the department of radiological technology. To evaluate the effects of KYT, we asked nine questions each to ten participants before and after KYT enforcement with regard to their attitude to patient safety and to operating procedures for working safely. RESULTS: Significant improvements after KYT enforcement were obtained in two items concerning medical safety: It is important for any risk to be considered by more than one person; The interest in preventive measures against medical accident degree conducted now) and one concerning operating procedures (It is necessary to have a nurse assist during testing with the mobile X-ray apparatus) (p<0.05). CONCLUSIONS: Performing KYT resulted in improved awareness of the importance of patient safety. KYT also enabled medical staffers to evaluate objectively whether the medical safety measures currently performed would be effective for patients.

[Observations of deterioration of photo-stimulable phosphor plates used in digital mammography and its effects on mammography diagnoses].

We noted that breast-like artifacts occur in photo-stimulable phosphor plates (PSPs) used for long periods in digital mammography systems. This prompted us to investigate the effects on mammography diagnoses of these artifacts. Our study took the form of a comparison between the images generated by a long-term use PSP (four years use) and a short-term use PSP. First, an acrylic phantom and an in-house-made phantom for visual evaluation were imaged using X-ray PSPs under the same exposure conditions. They were then scanned under the same conditions to generate images. The mean values of the digital signals were measured in the 35 locations of region of interest present in the images of the acrylic phantom. The images of the in-house-made phantom were then visually evaluated by five certified experts, who examined 22 clinical images taken with both PSPs while referring to a visual evaluation scale. Differences were detected in all the evaluated items: the short-term use PSP gave a higher rate than the long-term use PSP (p<0.01), suggesting that long-term use PSPs might adversely affect the results of diagnostic mammography.

Interstitial MR lymphography in mice: comparative study with gadofluorine 8, gadofluorine M, and gadofluorine P.

PURPOSE: We investigated the characteristics and capability of interstitial MR lymphography in mice using gadofluorine 8, gadofluorine M, and gadofluorine P. METHODS: We injected healthy mice with 0.5 µmol of Gd gadofluorine 8, gadofluorine M, or gadofluorine P subcutaneously into the right rear footpad and assessed the time courses of contrast enhancement in the lymph nodes. Six mice were studied for each contrast agent. We also used gadofluorine M to assess the lymphatic pathway from the right and left rear feet or tail. RESULTS: Contrast enhancement was demonstrated for the right popliteal, sacral, and iliac lymph nodes in all mice 5 minutes after injection of each of the 3 agents and decreased gradually. Enhancement in the lymph nodes was still detectable 30 minutes after injection of gadofluorine 8 or gadofluorine M. Enhancement became obscure sooner after gadofluorine P injection and was mildly stronger with the other 2 contrast agents. Clear differences were found in the hepatobiliary and urinary kinetics of the 3 agents. Gadofluorine M injected into various sites delineated the lymphatic pathway from the site of injection. CONCLUSION: Interstitial MR lymphography using gadofluorine 8, gadofluorine M, and gadofluorine P offered clear visualization of the lymphatic pathway in healthy mice during a sufficient imaging time window, and allowed repeated assessment of the pathway and clarification of the lymphatic system.

Morphological study of the human hyoid bone with three-dimensional CT images -Gender difference and age-related changes.

The human hyoid bone supports the base of the tongue and is involved in breathing, chewing, and swallowing as well as in the muscle movements associated with articulation. Accordingly it plays an important bone for a human to live. It is a very interesting organ also in multiple special area, including anatomy, mastication, swallowing, articulation, and also forensic medicine. In the morphological study of the human hyoid bone, there is a comparative anthropological research early in 1900, whereas the metrological research has been little reported later. We first used MDCT, and recorded each organic hyoid locus with a three-dimensional image for three-dimensional morphometry of gender differences, age-related changes, and the morphologic characters of the hyoid bone, and compared them with the results of our predecessors. By measuring the volume of the human hyoid bone, we identified gender difference at high rates, and estimated a certain level of ages based on the ossification at the junction area of the hyoid body and greater horns observed. Our results can be applied in the forensic medicine. By examining 600 cases, atypical horseshoes-shapes were found and the existence of the hyoid bone protrusion was demonstrated at high rates.

Integrated lymphography using fluorescence imaging and magnetic resonance imaging in intact mice.

We assessed lymph drainage in living mice by an integrated imaging method using fluorescence imaging (FLI) and magnetic resonance imaging (MRI). Mice were subcutaneously injected with quantum dots and gadofluorine 8 into the right rear footpad. They were fixed on a transparent flat plate and underwent FLI and MRI successively. Small markers were attached to the mouse surface for spatial coregistration, and image fusion of FLIs and MRIs was performed. Two-dimensional fluorescence reflectance imaging was used for FLI. FLI and MRI provided generally consistent results and demonstrated lymphatic flow to the popliteal, sacral, and iliac lymph nodes in most mice and to the renal, inguinal, and lumbar-aortic lymph nodes in some mice. On the fusion images, the locations of the lymph nodes in the mouse trunk were in good agreement between FLI and MRI, indicating successful spatial registration even for the deep structures. The popliteal node tended to be visualized a little farther caudally in FLI than in MRI, presumably because the overlying tissues were thicker in the cranial portion. Integrated FLI/MRI lymphography with image fusion appears to be a useful tool for analysis of the murine lymphatic system.

Distortion correction in whole-body imaging of live mice using a 1-Tesla compact magnetic resonance imaging system.

PURPOSE: The aim of this study was to establish a distortion correction applicable to whole-body imaging of live mice. MATERIALS AND METHODS: All magnetic resonance imaging (MRI) scans were acquired on a compact 1-T permanent magnet unit for mouse imaging using a T1-weighted, three-dimensional (3D) fast low-angle shot sequence. We assessed geometric distortion in MR images of a small 3D grid phantom and determined 3D image transformations for distortion correction. The developed distortion correction was applied to MR images of the 3D grid phantom acquired on another day, and the correction was validated. A two-dimensional (2D) grid phantom was imaged with a mouse to investigate the applicability of the distortion correction to whole-body mouse imaging. RESULTS: Obvious geometric distortion was observed in the MR images of the 3D grid phantom. The application of the developed 3D phantom-based distortion correction reduced distortion in the images of the 3D grid phantom acquired on another day. Geometric distortion was observed in the MR images of the 2D grid phantom acquired together with the mouse. The 3D phantom-based correction decreased the distortion substantially, regardless of mouse positioning. CONCLUSION: The developed distortion correction can reduce distortion in whole-body imaging of live mice and may enhance the capabilities of MRI in small animal experiments.

Diet and gastrointestinal signal on T1-weighted magnetic resonance imaging of mice.

In magnetic resonance (MR) imaging of small animals, the gastrointestinal contents may give rise to intense signals on T1-weighted images. The aim of this study was to determine the optimal dietary preparation to reduce gastrointestinal signals in mice and to evaluate the usefulness of this approach. Images of the mouse trunk were obtained using a T1-weighted, three-dimensional fast low-angle shot sequence under various dietary conditions and were compared with respect to the gastrointestinal signals and image quality. The dietary preparation studied included giving alternative diets for 24 h, intestinal cleansing, and 6-h fasting. Mice with and without dietary preparation underwent MR lymphography using gadofluorine 8, and the visualization of abdominal lymph nodes was compared. In the absence of dietary preparation, hyperintense areas were conspicuous in the gastrointestinal system, whereas on the images taken from mice fed potato or sweet potato for 24 h before imaging, gastrointestinal hyperintensity was less prominent. This preparation also reduced artifactual signals and resulted in higher-quality images of the kidneys. Intestinal cleansing, which consisted of 24-h fasting and laxative intake, did not reduce the gastrointestinal signals and caused signal changes that were indicative of fatty liver development. Some of the abdominal lymph nodes of the mice that did not receive dietary preparation were visualized on MR lymphography source images but not on maximum intensity projection (MIP) images. In contrast, on the MIP images of mice fed potato, all the lymph nodes delineated on the source images were successfully visualized. In conclusion, feeding mice potato or sweet potato for 24 h before MR imaging reduces the gastrointestinal signals and image degradation due to artifacts. Appropriate dietary preparations facilitate the display of target structures on MIP images and are expected to enhance the capabilities of small animal MR imaging.

Correlation between left ventricular diastolic function and ejection fraction in dilated cardiomyopathy using magnetic resonance imaging with late gadolinium enhancement.

BACKGROUND: The distribution of left ventricular (LV) fibrosis and the percent fibrosis in patients with dilated cardiomyopathy (DCM) were evaluated using late gadolinium enhanced (LGE) MRI. Then the relation with the LV ejection fraction (EF) and deceleration time (DT), an index of diastolic function obtained using echocardiography, was investigated. METHODS AND RESULTS: LGEMRI at 20 min after intravenous injection of Gd-DTPA (0.15 +/-0.03 mmol/kg) was performed in 17 patients with DCM. The distribution of the LV enhanced area and LGE rate (%) were calculated. EF, as well as E/A ratio and DT were obtained using echocardiography. LGE was observed in 15 out of 17 patients (88%) and the enhanced region appeared to represent myocardial fibrosis. The LV fibrosis was often found in the intraventricular septum (IVS), but there were no differences in its distribution. The LGE rate (%) had a correlation between cardiac magnetic resonance ejection fraction (CMREF) (Y = 51.7 - 2.1X [R(2) = 0.23, P<0.001]) and DT (Y = 162.2 +12.0X [R(2) = 0.35, P<0.001]). CONCLUSIONS: The LV fibrosis is often found in the IVS with DCM. A correlation exists between LGE rate (%) to EF on CMR and DT on echocardiography in patients with DCM.

Follow-up magnetic resonance imaging findings in patients with progressive multifocal leukoencephalopathy: evaluation of long-term survivors under highly active antiretroviral therapy.

PURPOSE: The aim of this study was to clarify the early magnetic resonance imaging (MRI) findings of progressive multifocal leukoencephalopathy (PML) and to evaluate the relations of the clinical course and serial MRI findings in patients with acquired immunodeficiency syndrome (AIDS)-related PML treated with highly active antiretroviral therapy (HAART). MATERIALS AND METHODS: The clinical course and serial MRI findings in five patients with AIDS-related PML who were treated with HAART are described. RESULTS: Although all five patients were serologically naive to the therapy and alive at the end of the observation period, the lesions showed rapid extension on MRI for up to 3 months after the start of the therapy, and clinical symptoms progressed rapidly for a month after the start of the therapy. Newer margins in spreading lesions showed a diffuse pale hyperintensity and/or many discrete hyperintense dots on T2-weighted images CONCLUSION: Early PML lesions may show a characteristic appearance on T2-weighted images. We should be aware of the progression of AIDS-related PML even under serologically effective HAART.

Evaluation of gadoxetate disodium as a contrast agent for mouse liver imaging: comparison with gadobenate dimeglumine.

We investigated the characteristics of gadoxetate disodium (Gd-EOB-DTPA) as a contrast agent for magnetic resonance imaging of the mouse liver. Mice were imaged sequentially under isoflurane anesthesia using a T1-weighted, three-dimensional fast low-angle shot (3D FLASH) sequence after an intravenous injection of Gd-EOB-DTPA or gadobenate dimeglumine (Gd-BOPTA), and the time course of the contrast effect was examined. The time course of the contrast effect of Gd-EOB-DTPA was also assessed after intravenous injection under pentobarbital anesthesia and after subcutaneous injection while awake or under isoflurane or pentobarbital anesthesia. Moreover, different doses of Gd-EOB-DTPA or Gd-BOPTA were injected subcutaneously into conscious mice, and the clarity of the liver border was evaluated visually. Intravenous injection under isoflurane anesthesia caused rapid contrast enhancement in the liver with both Gd-EOB-DTPA and Gd-BOPTA, and the contrast effect was 41% stronger with Gd-EOB-DTPA. Subcutaneous injection of Gd-EOB-DTPA caused delayed but favorable contrast enhancement in the liver. Washout of Gd-EOB-DTPA was faster in mice injected while awake than in those injected under anesthesia. After intravenous injection, washout was faster under pentobarbital anesthesia than under isoflurane anesthesia. The peak liver contrast was 11% and 18% stronger under pentobarbital anesthesia than under isoflurane anesthesia, after intravenous and subcutaneous injections, respectively. Subcutaneous injection of Gd-EOB-DTPA or Gd-BOPTA caused dose-dependent contrast effects in the liver. At a given dose, the contrast effect tended to be stronger and liver demarcation tended to be clearer with Gd-EOB-DTPA than with Gd-BOPTA. In conclusion, intravenous or subcutaneous injection of Gd-EOB-DTPA produces a favorable contrast effects in the mouse liver, indicating its potential in investigating mouse models of liver diseases. The contrast effects vary between conscious mice and anesthetized mice and among anesthetic agents used.

[Experimental study of the influence on pacemakers of X-rays from angiocardiography equipment].

We performed an experimental study of the influence on pacemakers (PM) of X-rays from the angiocardiography equipment. (1) We used one PM of DDD mode in this study. (2) The PM was irradiated under two exposure levels: one the standard dose and the other the maximum dose in the angiocardiography study situation. (3) We set the pacing lead wires to the bilateral atria and ventricles in Irnich's human body model. (4) We set two irradiation fields, one with a lead block on the PM and the other without the lead block. The result showed that when the PM was included in the irradiation field and the exposure level was of the maximum dose, the influence of irradiation on the PM was that of level 2 as classified by a research report by the Ministry of Internal Affairs and Communications. The absorbed dose of the PM was 93.4 mGy under these conditions. We confirmed that radiation dose does not affect a pacemaker with pacing lead wire. However, it acts on the generator of the PM owing to the direct photoelectric effect. When there were many dose rates (or total radiation dose), an obstacle occurred.

In vivo fascicle behavior of synergistic muscles in concentric and eccentric plantar flexions in humans.

Ultrasonography was used to directly measure in vivo fascicle behavior of the medial gastrocnemius (MG) and soleus (SOL) muscles while the subjects (n=6 men) performed maximal voluntary concentric and eccentric plantar flexions at 60, 120, 180 and 240 deg/s. Fascicle shortening and lengthening velocities of MG, obtained from fascicle length changes over time, were significantly higher than those of SOL at +/-120, +/-180 and +240 deg/s, possibly reflecting physiological and mechanical differences between these muscles. On the other hand, the effective fascicle shortening and lengthening velocities, defined as the velocities in the longitudinal direction of muscle belly, were not significantly different between MG and SOL. This could be due to difference in fascicle architecture and/or the existence of mechanical linkages between these muscles. Moreover, when the contribution of tendinous tissues to muscle-tendon complex length change was determined from fascicle length, pennation angle, moment arm and joint angle, it accounted for approximately 50% in both concentric and eccentric trials, but showed considerable intra-subject variations. This result quantifiably demonstrates the importance of tendinous tissues in isokinetically controlled joint movements.