Development of anisotropic phantoms using wood and fiber materials for diffusion tensor imaging and diffusion kurtosis imaging.

OBJECTIVE: Several studies have demonstrated that anisotropic phantoms can be utilized for diffusion magnetic resonance imaging. The purpose of our study was to examine whether wood is suitable as an anisotropic phantom material from the viewpoints of affordability and availability. In the current study, wood was used for restricted diffusion, and fibers were used for hindered diffusion. MATERIALS AND METHODS: Wood and fiber phantoms were made. Diffusion kurtosis images were acquired with three magnetic resonance scanners. Fractional anisotropy, radial diffusivity, axial diffusivity, radial kurtosis and axial kurtosis values were measured. The wood phantom was imaged, and its durability was confirmed. The phantoms were imaged in varying orientations within the magnetic field. The wood was observed using an optical microscope. RESULTS: Ten kinds of wood and the fiber had a diffusion metrics. The wood diffusion metrics suggested low variation over a period of 9 months. Changing the orientation of the phantoms within the magnetic field resulted in changes in diffusion metrics. Observation of wood vessels and fibers was conducted. DISCUSSION: Wood and fibers have anisotropy and are promising as phantom materials. The development of anisotropic phantoms that anyone can use is useful for diffusion magnetic resonance imaging research and clinical applications.

90°-flip-angle three-dimensional double-echo steady-state (3D-DESS) magnetic resonance imaging of the knee: isovoxel cartilage imaging at 3T.

PURPOSE: The purpose of this study was to investigate whether 3D-double echo steady state (3D-DESS) with improved contrast by setting the FA (Flip angle) at 90° is useful in 3D isotropic cartilage imaging of the knee at 3T. MATERIALS AND METHODS: Imaging was performed in 10 healthy volunteers using 3 methods: with 3D-DESS using FA of 25° and 90°, and with true fast imaging with steady-state precession (True-FISP). The signal-to-noise ratio (SNR) of the synovial fluid and cartilage, and contrast-to-noise ratio (CNR) were measured, and mean values were compared. Visual assessment of artifacts was performed with the cartilage divided into 6 regions. RESULTS: There were no significant differences in synovial fluid SNR in the comparison between FA-90° 3D-DESS and True-FISP (P=0.364). A significantly higher cartilage SNR was observed with FA-90° 3D-DESS than with True-FISP (P=0.031). There were no significant differences in synovial fluid-cartilage CNR between FA-90° 3D-DESS and True-FISP (P=0.892). In the evaluation of artifacts, FA-90° 3D-DESS imaging showed a significantly higher score than True-FISP imaging in the patella and trochlea cartilage (P<0.001, P<0.002). CONCLUSIONS: FA-90° 3D-DESS is useful in 3D isotropic cartilage imaging of the knee at 3T.

Flour pads: devices to improve CHESS fat suppression.

PURPOSE: We compared the suppression of lingering fat signals in chemical shift selective (CHESS) images by pads filled with flour and pads filled with rice in a phantom and human subjects. MATERIALS AND METHODS: First, we prepared a phantom by creating an empty space in a mass of lard and filling the space with air, rice, or flour. Then, we obtained MR images of the phantoms in the center of the magnetic field and at a position 8 cm to the left (off-center) to compare lingering fat signals. MR images of the knee were obtained in 10 healthy volunteers using CHESS after placing a polyurethane sponge pillow, rice pad, or flour pad in the popliteal space under the flexed knee. We visually assessed the number of areas with lingering fat signals and the statistical differences among the groups were assessed using Tukey's test. RESULTS: Similarly to rice, flour clearly decreased lingering fat signals in the phantom study. A similar effect was obtained in the off-center images. In the volunteer study, the mean number of areas with lingering fat signals was 2.5 with a sponge pillow, 0.5 with the rice pad, and 0.3 with the flour pad. Those numbers were significantly different using flour pad and rice pad compared with sponge pillow (P < 0.001). No significant differences were seen between flour pads and rice pads (P = 0.662). CONCLUSION: Flour pads can suppress lingering fat signals in CHESS images.

Lingering fat signals with CHESS in simultaneous imaging of both hands can be improved with rice pads in both 1.5T and 3.0T.

OBJECTIVES: To investigate whether rice pads can eliminate lingering fat signals of the complex surface shape of both hands that occur with chemical shift selective (CHESS) at 1.5T and 3.0T. MATERIALS AND METHODS: T1-weighted images were obtained with CHESS using 1.5T and 3.0T systems. The same imaging parameters were used with and without rice pads on the coronal plane of both hands in 10 healthy volunteers. The fat-suppression effects were classified into four categories and scored for images, and visual evaluations were performed by one radiologist and one radiologic technologist. RESULTS: At 1.5T, the mean evaluation score was 1.55 for images obtained without rice pads and 3.50 for images obtained with rice pads. At 3.0T, the mean evaluation score was 1.10 for images obtained without rice pads and 3.20 for images obtained with rice pads. With both systems, images obtained with the rice pads showed significantly better fat suppression effects than images obtained without rice pads (P<0.0001, P<0.0001). CONCLUSIONS: It was confirmed that lingering fat signals are eliminated and good fat-suppressed images are obtained with the use of rice pads at 1.5T and 3.0T. Rice pads are therefore useful with at 1.5T and 3.0T, which are currently becoming more widely used.

Three-dimensional double-echo steady-state (3D-DESS) magnetic resonance imaging of the knee: establishment of flip angles for evaluation of cartilage at 1.5 T and 3.0 T.

BACKGROUND: The effect of flip angle (FA) on synovial fluid and cartilage signal and on image contrast using three-dimensional double-echo steady-state (3D-DESS) sequence have only been performed with 1.0-T but not with 1.5-T or 3.0-T scanners. PURPOSE: To identify the FA that gives the maximum synovial fluid and cartilage values, and to identify the FA at which maximum values of synovial fluid-cartilage contrast-to-noise ratio (CNR) in 3D-DESS sequences when 1.5-T and 3.0-T scanners are used. MATERIAL AND METHODS: Using 3D-DESS with water-excitation pulse, mid-sagittal plane images of the knees of 10 healthy volunteers (5 men, 5 women; age range, 21-42 years) were obtained with FA varying from 10° to 90°. Synovial fluid signals, cartilage signals, and background were measured at each FA, and the FA that gave the highest synovial fluid and cartilage values was obtained. Synovial fluid-cartilage CNR was also calculated, and the FA that gave the largest CNR was obtained. RESULTS: At 1.5 T, the maximum synovial fluid signal was at FA 90°, and the maximum cartilage signal was at FA 30°. Synovial fluid-cartilage CNR was highest at FA 90° (P < 0.05). At 3.0 T, the maximum synovial fluid signal was at FA 90°, and the maximum cartilage signal was at FA 20°. Synovial fluid-cartilage CNR was highest at FA 90° (P < 0.05). CONCLUSION: In order to improve the visibility of cartilage itself, FA settings of 30° at 1.5 T and 20° at 3.0 T are apparently ideal. For observing the cartilage surface, the most effective FA setting is 90° for both 1.5 T and 3.0 T.

Fat-suppressed MR images of both hands obtained using CHESS can be improved by rice pads.

When chemical shift selective (CHESS) imaging is used with magnetic resonance imaging (MRI) for simultaneous imaging of both hands for the evaluation of rheumatoid arthritis, the fat suppression effect is poor. We investigated whether these fat-suppressed images using CHESS could be improved with the use of rice pads. T1-weighted images were obtained with CHESS and the same imaging parameters were used with and without rice pads on the coronal plane of both hands in 10 healthy volunteers. Patients were placed in a prone position with both hands extended overhead. The fat-suppression effect was classified into four categories and scored for both sets of images, and visual assessments were made by one radiologist and one radiologic technologist. The evaluation score was 1.1 for the images made without rice pads, and 3.2 for the images made with rice pads. The fat suppression effect was thus significantly better in the images made using rice pads (P<0.0001). Lingering fat signals disappeared almost completely in images of both hands using CHESS with rice pads, and it was confirmed that the images were improved and had good fat suppression. More accurate evaluation of inflammatory sites that occur in rheumatoid arthritis may thus be possible, promising better diagnostic accuracy.

Evaluation of cartilage surface injuries using 3D-double echo steady state (3D-DESS): effect of changing flip angle from 40° to 90°.

BACKGROUND: In magnetic resonance imaging (MRI) with 3D-double-echo steady-state (3D-DESS) sequences, the cartilage-synovial fluid contrast is reported to be better with a flip angle of 90° than with the conventional flip angle of 40°, and the detection rate of knee cartilage injury may be improved. PURPOSE: To compare the diagnostic performance and certainty of diagnosis with 3D-DESS images made using two flip angle settings, 40° and 90°, for knee cartilage surface lesions of Grade 2 or above confirmed by arthroscopy. MATERIAL AND METHODS: Images were obtained with 3D-DESS flip angles of 40° and 90° at 1.0T in 13 consecutive patients (2 men, 11 women, age range 18-68 years) evaluated for superficial cartilage injury by arthroscopy. Two radiologists classified the presence or absence of cartilage damage of ≥Grade 2 as 'positive (p)' or 'negative (n)', respectively. The rate of agreement with arthroscopic diagnosis was then examined, and the diagnostic performance compared. Diagnostic confidence was assessed scoring the presence or absence of cartilage damage into three categories: 3 = can diagnose with absolute confidence; 2 = can diagnose with a level of certainty as probably present or probably absent; and 1 = cannot make a diagnosis. RESULTS: In a comparison of the rate of agreement between diagnosis by 3D-DESS images and arthroscopy, the rate of agreement was significantly higher and diagnostic performance was better in 90° images for the medial femoral condyle only. Diagnostic confidence was significantly better with 90° flip angle images than with 40° flip angle images for all six cartilage surfaces. CONCLUSION: In evaluating knee cartilage surface lesions with 3D-DESS sequences, a flip angle setting of 90° is more effective than the conventional setting of 40°.

Optimization of the number of selectable channels for spine phased array coils for transverse imaging.

PURPOSE: The aim of this study was to investigate whether the signal-to-noise ratio (SNR) in transverse images acquired from spine phased array coils is improved by deactivating coils distant from the imaging region and to identify the optimum coil settings. MATERIALS AND METHODS: Ten healthy volunteers (five men, five women; average age 38 years) underwent transverse magnetic resonance imaging (MRI) of the cervical spine using four to one channels of a four-channel phased array coil for cervical imaging. The SNR of cerebrospinal fluid (CSF), spinal cord, muscle tissue, intervertebral disc, vertebral body, and prevertebral soft tissue was measured for each coil combination. RESULTS: In all measured regions, the SNR was the highest for images acquired using two coils; the SNR was significantly higher for two coils than for four coils in CSF, spinal cord, muscle tissue, intervertebral disc, vertebral body, and prevertebral soft tissue (P < 0.001, P = 0.019, P < 0.0001, P = 0.014, P = 0.010, P < 0.001). CONCLUSION: Deactivating two of the four coils used for sagittal sections, meaning that two coils are active, resulted in improved SNR for transverse images. Selecting the optimum number and combination of coils for each imaging cross section may enable acquisition of images with a better SNR.

Rice pads reduce geometric distortion of echo-planar diffusion-weighted images of the cervical spinal cord.

We investigated whether a rice pad could be used to reduce the geometric distortion in echo-planar diffusion-weighted images of the cervical spinal cord. In 10 healthy volunteers, we obtained sagittal plane images using the same imaging parameters with and without a rice pad. Two reviewers classified geometric distortion and visually assessed images. Use of a rice pad significantly reduced geometric distortion in the cervical spinal cord.

Improved CHESS imaging with the use of rice pads: Investigation in the neck, shoulder, and elbow.

PURPOSE: To investigate the feasibility of rice pads for improving nonuniform fat suppression in magnetic resonance imaging (MRI) of the neck, shoulder, and elbow using the chemical shift selective (CHESS) technique. MATERIALS AND METHODS: CHESS imaging of the neck, shoulder, and elbow was performed on 10 healthy volunteers with and without the use of rice pads. Images were visually assessed by one radiologist and one radiologic technologist using a four-point scale. Results were compared using Wilcoxon's signed rank sum test. RESULTS: Images with and without rice pads were rated 3.9 and 1.5 for the neck (P = 0.002), 3.85 and 2.5 for the shoulder (P = 0.002), and 3.4 and 2.45 for the elbow (P = 0.004). CONCLUSION: Fat-suppressed images obtained using the CHESS technique were significantly improved by rice pads for the neck, shoulder, and elbow, indicating that image deterioration with CHESS caused by magnetic field nonuniformity can be improved by rice pads in all body areas.

Rice and perfluorocarbon liquid pads: comparison of fat suppression effects.

BACKGROUND: With the chemical shift selective (CHESS) method, lingering fat signals remain because of the effects of nonuniformity in the magnetic field. One method to reduce this phenomenon is the use of pads filled with rice (rice pad), but the improvement in fat suppression effects with rice pads, as compared with conventional perfluorocarbon liquid pads, remains unclear. PURPOSE: To investigate whether rice pads are superior to perfluorocarbon liquid pads in improving fat suppression effects in magnetic resonance imaging (MRI) examination of the knee. MATERIAL AND METHODS: Subjects were 10 healthy volunteers (5 men, 5 women; aged 20-45 years), from whom images taken using the CHESS methods were collected. Two images were taken for each subject; one with a rice pad placed under the knee and the knee flexed, and the other with a perfluorocarbon liquid pad placed under the knee and the knee flexed. Images were visually assessed by one radiologist and one radiologic technologist. Kendall's W and Wilcoxon signed rank test were used for statistical comparisons. RESULTS: Of the 20 evaluations made by the 2 observers, scores for images obtained with the rice pad were higher than those with the perfluorocarbon liquid pad in 18 cases, while the scores were equal in 2 cases. Images with the rice pad were not inferior in any cases. The mean score for visual assessment was 4.65 for the rice pad and 3.0 for the perfluorocarbon liquid pad. The rice pad was thus confirmed to be superior to the perfluorocarbon liquid pad (P=0.0039). CONCLUSION: The rice pad exhibited better performance in improving the fat suppression effect. Thus, the rice pad is a superior product that is inexpensive and simple to use.

Rice pads: novel devices for homogeneous fat suppression in the knee.

BACKGROUND: In magnetic resonance imaging (MRI) of the knee joint, when imaging the knee in a flexed position using the chemical-shift-selective (CHESS) method, lingering fat signals in the popliteal region are sometimes seen. PURPOSE: To investigate whether a pad filled with rice (rice pad) placed in the popliteal space is effective in eliminating the lingering fat signals in MR images of the flexed knee, based on the hypothesis that the use of a rice pad would improve the fat suppression effect. MATERIAL AND METHODS: Subjects were 10 healthy volunteers (five males, five females; age, 20-45 years) from whom images were taken using CHESS. Images were obtained with: 1) the knee extended and nothing placed underneath; 2) the knee bent with a sponge placed underneath; and 3) the knee bent with a rice pad placed underneath. The effectiveness of suppressing fat signals was visually assessed by one radiologist and one radiological technologist. RESULTS: The fat suppression effect in images obtained with the knee extended was good. In contrast, the images made with a sponge under the knee had conspicuous lingering fat signals for nearly all subjects. In the images made with a rice pad under the knee, a uniformly good fat signal suppression effect was seen in all patients, and the assessment score was far higher than that with the sponge pillow (P<0.001). CONCLUSION: Lingering fat signals were suppressed with the use of a rice pad, and fat-suppressed images of the knee joint using CHESS were found to be improved.

An inverse association between serum gamma glutamyl transpeptidase activity and Breslow's Lifestyle Index; its practical application for screening of subjects with unhealthy lifestyles.

We examined whether serum gammaGTP activity (gammaGTP) is associated with Breslow's lifestyle index and whether it could be used as a tool to detect subjects with unhealthy lifestyles. To that effect, 724 male Japanese workers excluding patients suffering from hepatitis virus infection, autoimmune liver diseases and apparently active bile duct diseases were cross-sectionally examined. gammaGTP was inversely associated with the total score of Breslow's index for all subjects (lambda=30.643) and in subjects aged 40 or more (lambda=37.073). The association was consistent even after adjustments of subjects' ages and levels of triglycerides, total cholesterol and uric acid (p=0.0001). Among the seven lifestyle factors comprising Breslow's index, improper habits of drinking (p<0.0001), smoking (p=0.0204), exercise (p=0.0189) and body weight control (p<0.0001), were associated with increased gammaGTP. Even in a survey in which subjects who had proper habits of drinking and body weight control were selectively examined, improper habits of smoking and exercise still tended to be associated with increased gammaGTP. Receiver operating characteristic curves indicated that gammaGTP was beneficial for detecting subjects who scored two or less on Breslow's index, at least in subjects aged 40 or more. gammaGTP was associated with insulin resistance level estimated by the homeostasis model assessment (p<0.0001), which was inversely associated with Breslow's index (p=0.0040). gammaGTP could be used as an objective substitute of Breslow's index, allowing us to identify subjects with low scores on Breslow's index, at least after sorting subjects properly. Such screening would enable interventions to correct subjects' unhealthy lifestyles, helping to solve lifestyle-related disease issues.

Correlation between insulin resistance and gamma-glutamyl transpeptidase sensitivity in light drinkers.

BACKGROUND: Our previous studies suggested that serum gamma-glutamyl transpeptidase (GGTP) level was correlated with insulin resistance level estimated by the homeostasis model assessment in teetotalers and occasional drinkers. In the surveys, strong correlation between GGTP and triglyceride also was observed. This study examined whether the correlation held true for regular drinkers. METHODS: Seven hundred and seventeen male subjects in annual health checkups were divided into three groups according to their drinking styles and further divided into four subgroups according to their serum GGTP levels. In the other surveys, they were ranked by their amount of ethanol consumption. The correlation between GGTP and insulin resistance level was studied in each group. RESULTS: Single regression analysis and analysis of variance showed that GGTP level was significantly correlated with insulin resistance level as determined by the homeostasis model assessment, as well as with triglyceride level regardless of subjects' drinking styles. The associations were confirmed by multiple regression analyses in which age, levels of uric acid, total cholesterol, high-density lipoprotein cholesterol, and body mass index were adjusted, at least in nondrinkers or light drinkers. However, the multiple regression analyses indicated that the association between GGTP and insulin resistance level was not significant in subjects who take ethanol more than five times per week. The studies according to the amount of subjects' ethanol consumption indicated that the association between GGTP and insulin resistance was significant in the subjects who take ethanol up to 280 g/week. CONCLUSION: Individual variation in insulin resistance status may contribute to individual variations of sensitivity of GGTP to ethanol intake, at least in light drinkers.

Association between gamma-glutamyl transpeptidase activity and status of disorders constituting insulin resistance syndrome.

BACKGROUND: Serum gamma-glutamyl transferase (gamma GTP) activity is a well-established marker of alcohol consumption. However, recently, a correlation between serum gamma GTP activity and insulin resistance status has been demonstrated. METHODS: To determine whether serum gamma GTP activity could be associated with the status of various disorders caused by increased insulin resistance levels, namely, insulin resistance syndrome, a cross-sectional study for 11,884 Japanese men was performed. They were divided into three groups by their age, and associations between gamma GTP and various indexes of insulin resistance syndrome were studied by multiple logistic regression analysis in which subjects' drinking styles were corrected for in each age bracket. RESULTS: Consuming ethanol more than 40 g/day, body mass index more than 25.9 kg/m2, and triglyceride levels more than 150 mg/dl were significant risk factors accounting for increased gamma GTP activity (more than 78 IU/liters) irrespective of age. In addition, when subjects of 40 to 59 years old were selectively studied, hypertension, hypercholesteremia, hyperuricemia, and increased glycohemoglobin A1C levels were also significant risk factors for increased gamma GTP activity. CONCLUSIONS: There are significant associations between gamma GTP and the status of insulin resistance syndrome. In addition to excessive alcohol consumption, the status of insulin resistance syndrome could affect subjects' gamma GTP activities.

Significant correlation between insulin resistance and serum gamma-glutamyl transpeptidase (gamma-GTP) activity in non-drinkers.

To understand the significance of elevated serum gamma-GTP levels, factors relevant to the serum gamma-GTP level were studied using data of health check-ups for the employees of a Japanese corporation. The gamma-GTP level was positively correlated with levels of various liver function tests including aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Except for them, the gamma-GTP level was positively correlated with levels of insulin resistance, uric acid, total cholesterol, triglyceride, and body mass index. The correlation between the gamma-GTP level and LDL cholesterol was also observed only when subjects who drank more than 5 times a week were selectively studied. When non-drinkers and opportunity drinkers were selectively studied, 63.6% of subjects whose gamma-GTP level was more than 120 IU/liter showed elevated insulin resistance levels. Multiple factors including insulin resistance may affect serum gamma-GTP activity in clinical subjects.

Anaphylactic transfusion reactions in haptoglobin-deficient patients with IgE and IgG haptoglobin antibodies.

BACKGROUND: Patients with haptoglobin deficiency associated with haptoglobin IgG antibodies, who experienced severe nonhemolytic transfusion reactions (NHTRs), have been identified in Japan. Haptoglobin deficiency therefore might be a risk factor for NHTRs. STUDY DESIGN AND METHODS: A total of 4138 cases of voluntarily reported NHTRs in Japan, including 367 cases of immediate-onset anaphylactic NHTRs, were examined to identify haptoglobin deficiency. Serum haptoglobin IgG and IgE antibodies were determined in haptoglobin-deficient patients to elucidate the mechanism underlying the transfusion reactions. RESULTS: Seven patients with haptoglobin deficiency were identified. Six of them experienced severe and acute NHTRs. Six of them were identified to be homozygous for the Hpdel allele of the haptoglobin gene. Both haptoglobin IgG and IgE antibodies were detected in serum samples of all the patients. The stimulative effects of blood transfusion on the production of hap- toglobin antibodies in the patients and the relation- ship between the presence of the antibodies and the occurrence of the transfusion reactions were observed. CONCLUSION: Anaphylactic NHTRs in these patients with haptoglobin deficiency associated with serum haptoglobin antibodies were suggested to be prevalent in Japan. In addition to IgG antibodies, IgE haptoglobin antibodies detected in the sera of such patients were suggested to play a role in the occurrence of the reactions.