Prediction of tissue deformation based on mechanical and physiological factors in the prone position during surgery.

AIM: This study aimed to predict tissue deformation based on the pressure applied while lying in the prone position and physiological factors. METHODS: Healthy volunteers were instructed to lie on mattresses of four different hardness levels (50, 87.5, 175, and 262.5 N). The order in which the mattresses were used was randomized per participant. Pressure at the iliac crests was measured using a pressure mapping sensor sheet. Participants were placed in the prone position for 10 min, with pressure data used from the latter 5 min. For the tissue deformation at the iliac crests, our previous study data were used. Multiple regression analysis was used to identify predictive mechanical and physiological factors. RESULTS: The distance between the left and right greater trochanters, maximum interface pressure and age were significant predictors for compression of the skin and soft tissue. Significant predictors of internal soft tissue displacement were the distances between the left and right anterior superior iliac spines and greater trochanters. No factors predicted skin surface displacement. CONCLUSIONS: Our study provided predictive factors that may be measured easily in a clinical setting to reduce the risk of pressure ulcers during surgery in the prone position.

Evaluation of Brain Tumors Using Amide Proton Transfer Imaging: A Comparison of Normal Amide Proton Transfer Signal With Abnormal Amide Proton Transfer Signal Value.

OBJECTIVE: The aim of the study was to evaluate the relationship of amide proton transfer (APT) signal characteristics in brain tumors and uninvolved brain tissue for patients with glioblastoma and those with brain metastases. METHODS: Using the mDIXON 3D-APT sequence of the fast spin echo method, an APT image was obtained. The mean APT signal values of tumor core, peritumor edema, ipsilateral normal-appearing white matter (INAWM), and contralateral normal white matter (CNAWM) were obtained and compared between glioblastoma and brain metastases. Receiver operating characteristic curves were used to evaluate parameters for distinguishing between glioblastoma and brain metastases. In addition, the difference and change rate in APT signal values between tumor core and peritumoral edema (PE) and CNAWM were evaluated, respectively. RESULTS: The APT signal values of glioblastoma were the highest in tumor core (3.41% ± 0.49%), followed by PE (2.24% ± 0.29%), INAWM (1.35% ± 0.15%), and CNAWM (1.26% ± 0.12%, P < 0.001). The APT signal value of brain metastases was the highest in tumor core (2.74% ± 0.34%), followed by PE (1.86% ± 0.35%), INAWM (1.17% ± 0.13%), and CNAWM (1.2% ± 0.09%, P < 0.01). The APT change rate (between PE and CNAWM) was not significantly different at 78% and 56% for glioblastoma and brain metastases, respectively ( P > 0.05). CONCLUSIONS: Performing APT imaging under the same parameters used in this study may aid in the identification of brain tumors.

Spatial analysis of acoustic noise transfer function with a human-body phantom in a clinical MRI scanner.

BACKGROUND: The acoustic noise in magnetic resonance imaging (MRI) potentially depends on the measurement position and presence of a patient inside the scanner bore. PURPOSE: To analyze the spatial characteristics of the acoustic noise by using the gradient-pulse-to-acoustic-noise transfer function (GPAN-TF) with and without a human-body phantom on the examination table. MATERIAL AND METHODS: Acoustic noise waveforms were acquired at 80 and 110 measurement positions with and without a phantom. The GPAN-TFs µPa/(mT/m) in the coils were calculated by deconvolution. The phantom effect on the spatial distribution of the acoustic noise was assessed using the peak sound pressure levels (SPLs), mean values, peak values, and peak frequencies of the GPAN-TFs. RESULTS: The peak SPLs in all positions for the X-, Y-, and Z-gradient coils were increased by 11.1 dB, 1.4 dB, and 6.1 dB, respectively, compared with the peak SPL of the magnetic isocenter. The maximum peak SPLs among all positions of the X-, Y-, and Z-gradient coils with the phantom were increased by 4.9 dB, 7.4 dB, and 6.9 dB, respectively, relative to those without the phantom. However, the peak SPLs decreased at some positions with the phantom placed on the table (X-gradient coil = 4.6 dB, Y-gradient coil = 5.0 dB, Z-gradient coil = 8.4 dB). The most common peak frequencies were in the range of 2000-3000 Hz. CONCLUSION: "Hotspot" areas with and without the phantom were associated with acoustic noise sources in the clinical MRI scanner and were enhanced by the phantom's presence.

Extrusion of the medial meniscus under a weight-loading condition in early knee osteoarthritis: an investigation using special upright magnetic resonance imaging.

BACKGROUND: Whether the medial meniscus morphology and movement occur under upright loading conditions in early knee osteoarthritis (OA) or medial meniscus posterior root tear (MMPRT) remains unknown. This study aimed to evaluate the medial and anteroposterior extrusion of the medial meniscus under unloaded and upright-loaded conditions in patients with early knee OA. METHODS: Twelve patients with early knee OA and 18 healthy adult volunteers participated in this study. Magnetic resonance imaging using special equipment was performed with the participants in the unloaded and upright-loaded conditions. Medial, anterior, and posterior extrusions of the medial meniscus against the tibial edge were evaluated and compared between the early knee OA and healthy adult control groups. Additionally, 12 patients in the early knee OA group were divided into 2 subgroups based on whether MMPRT was observed, and the extrusion of the medial meniscus was compared. RESULTS: The amount of medial extrusion of the medial meniscus in both the unloaded and upright-loaded conditions was significantly greater in the early knee OA group than in the control group (unloaded: 2.6 ± 1.0 mm vs 0.7 ± 0.5 mm; upright-loaded: 3.7 ± 0.9 mm vs 1.8 ± 0.8 mm). Similarly, the anterior and posterior extrusion of the medial meniscus in the upright-loaded condition was significantly larger in the early knee OA group (anterior: 4.6 ± 1.0 mm vs 3.7 ± 1.1 mm; posterior: -3.4 ± 1.1 mm vs -4.6 ± 1.6 mm). However, no difference was observed in meniscal extrusion between unloaded and upright-loaded conditions. The posterior extrusion of the medial meniscus in the upright-loaded condition was significantly greater in MMPRT cases than in non-MMPRT cases in the early knee OA group (MMPRT: -2.7 ± 1.1 mm; non-MMPRT -4.1 ± 1.5 mm). CONCLUSIONS: In early knee OA, significantly large meniscal extrusions of the medial meniscus in both unloaded and upright-loaded conditions were found compared with healthy adults. Among patients with early knee OA, those with MMPRT showed a large posterior extrusion of the medial meniscus in the upright-loaded condition compared with those without MMPRT. LEVEL OF EVIDENCE: Level IV.

Validating scapular motion measurements using an optical motion analyzer and gravity magnetic resonance imaging.

[Purpose] This study aimed to validate whether scapular motion measured using a pad with retroreflective markers and optical motion analyzer (VICON MX) can reflect the motion calculated by images using multi-posture (gravity) magnetic resonance imaging. [Participants and Methods] The participants were 12 healthy males (12 dominant-side shoulders). The measurement items were the scapular angle at shoulder flexion 140° and 160° and abduction 100°, 120°, 140°, and 160°. The scapular angle changes were extracted from the upward/downward and internal/external rotations. Angular changes were calculated by subtracting the scapular angle in static position (drooped upper limb and external shoulder rotation) during resting chair sitting from the scapular angle in each of the six limb positions and subtracting it at shoulder abduction 100° from the scapular angle at shoulder abduction 120°, 140°, and 160°. [Results] The results showed no agreement in most cases and no consistent bias. [Conclusion] The result questions the validity of scapular motion analysis using pads with optical markers. However, the facility environment imposes many study limitations, and this method requires further validation eventually.

Combined maximum b-value and echo time: A practical method for determining the signal-to-noise ratio for magnetic resonance images.

PURPOSE: The aim of the present study is to develop a simple and practical method for measuring the signal-to-noise ratio (SNR) of magnetic resonance images called combined maximum b-value and echo time (COMBET) that could be suitable for pulse sequences to which a diffusion gradient can be applied. METHODS: In the COMBET method, we first obtain a signal image using the objective pulse sequence. Then, we obtain the noise image of this sequence using the diffusion gradient with the largest b-value and longest echo time. However, other imaging parameters are the same as those used for the signal image acquisition. The SNR is calculated from the mean signal intensity in the region of interest (ROI) of the signal image divided by the signal standard deviation in the ROI of the noise image after the required corrections. We compared SNRs determined using the COMBET and double echo with the longest second echo time (DELSET) methods for single-shot echo-planar imaging and fast spin-echo sequences in white mineral oil phantom, purified water phantom, human head, and upper abdomen. We used the subtraction method as the reference standard. RESULTS: The COMBET method could obtain the optimal noise image, whereas the DELSET method could not sufficiently suppress the long T2 signal in the purified water phantom, cerebrospinal fluid, and digestive fluid. Therefore, the DELSET method afforded incorrect results for the long T2 regions in the noise and SNR maps, while the COMBET method enabled the in vivo evaluation of the SNR even in the long T2 regions. CONCLUSION: The COMBET method allows simple and practical SNR measurement, which is applicable to tissues with long T2 relaxation time.

Sigmoid model analysis of breast dynamic contrast-enhanced MRI: Distinguishing between benign and malignant breast masses and breast cancer subtype prediction.

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is performed to distinguish between benign and malignant lesions by evaluating the changes in signal intensity of the acquired image (kinetic curve). This study aimed to verify whether the existing breast DCE-MRI analyzed by the sigmoid model can accurately distinguish between benign and invasive ductal carcinoma (IDC) and predict the subtype. A total of 154 patients who underwent breast MRI for detailed breast mass examinations were included in this study (38 with benign masses and 116 with IDC. The sigmoid model involved the acquisition of images at seven timepoints in 1-min intervals to determine the change in signal intensity before and after contrast injection. From this curve, the magnitude of the increase in signal intensity in the early phase, the time to reach the maximum increase, and the slopes in the early and late phases were calculated. The Mann-Whitney U-test was used for the statistical analysis. The IDC group exhibited a significantly larger and faster signal increase in the early phase and a significantly smaller rate of increase in the late phase than the benign group (P < 0.001). The luminal A-like group demonstrated a significantly longer time to reach the maximum signal increase rate than other IDC subtypes (P < 0.05). The sigmoid model analysis of breast DCE-MRI can distinguish between benign lesions and IDC and may also help in predicting luminal A-like breast cancer.

Comparison of each bundle of the spring ligament complex between the standing and supine positions: A multiposture magnetic resonance imaging study.

BACKGROUND: The spring ligament complex (SLC) supports the medial longitudinal arch of the foot, particularly in standing. We evaluated posture-related changes in the thickness and length of the three SLC bundles and their histology. METHODS: The thickness and length of the supramedial calcaneonavicular ligament (smCNL), medioplantar oblique calcaneonavicular ligament (mpoCNL), and inferoplantar calcaneonavicular ligament (iplCNL) were measured in the supine and standing positions, using a multiposture magnetic resonance imaging system, in 72 healthy adult feet. Histological examination was performed for 10 feet from five cadavers. RESULTS: The smCNL thickness decreased and its length increased from the supine to the standing position (P < 0.001); no other posture-related effects were noted. Histologically, smCNL fibers overlapped along multiple directions while mpoCNL and iplCNL, fibers were oriented horizontally along the longitudinal axis and vertically along the short axis, respectively. CONCLUSION: The complex, multidirectional, orientation of the smCNL allows an adaptive response to changes in loading.

Reliability of lower leg muscle thickness measurement along the long axis of the muscle using ultrasound imaging, in a sitting position.

[Purpose] To verify the reliability and validity of lower leg muscle thickness (MT) assessment along the muscle's long axis using ultrasound imaging (USI) in a sitting position. [Participants and Methods] Twenty healthy adult female participants (aged, 20.3 ± 0.9 years) were included in the study. Intra- and inter-examiner reliability of the proximal, middle, and distal MT of the tibialis anterior (TA) and medial head of the gastrocnemius (GM) were verified using USI in a sitting position. Additionally, the relationship between MT measurement using USI and muscle cross-sectional area (MCSA) measurement using magnetic resonance imaging (MRI), as well as the ankle joint's maximum muscle strength, were examined. [Results] The reliability of TA and GM MT measurement using USI was high for all regions. The relationship between MCSA measurement using MRI and MT measurement using USI showed a significant correlation in all the regions for both muscles. The relationship between ankle muscle strength and USI of MT was not significantly correlated in any region for both muscles. [Conclusion] Measurement of MT using USI is reliable and valid for MCSA, but must be combined with assessments of other factors for muscle strength.

Quantification of Regional Cerebral Blood Flow Using Diffusion Imaging With Phase Contrast.

BACKGROUND: The perfusion-related diffusion coefficient obtained from triexponential diffusion analysis is closely correlated with regional cerebral blood flow (rCBF), as assessed by arterial spin labeling (ASL) methods. However, this provides only a semiquantitative measure of rCBF, thereby making absolute rCBF quantification challenging. PURPOSE: To obtain rCBF in a noninvasive manner using a novel diffusion imaging method with phase contrast (DPC), in which the total CBF from phase-contrast (PC) MRI was utilized to convert perfusion-related diffusion coefficients to rCBF values. STUDY TYPE: Prospective. SUBJECTS: Eleven healthy volunteers (nine men and two women; mean age, 23.9 years) participated in this study. FIELD STRENGTH/SEQUENCE: A 3.0 T, single-shot diffusion echo-planar imaging with multiple b-values (0-3000 s/mm2 ), PC-MRI, pulsed continuous ASL, and 3D T1 -weighted fast field echo. ASSESSMENT: rCBF and its correlations in the gray matter (GM) and white matter (WM) were compared between DPC and ASL methods. rCBF in the GM and WM and the GM/WM ratio were compared with the literature values obtained using [15 O]-water positron emission tomography (15 O-H2 O PET). STATISTICAL TESTS: Spearman's correlation coefficient and Wilcoxon signed-rank test were used. Significance was set at P < 0.05. RESULTS: A significant positive correlation between DPC and ASL in terms of rCBF was observed in GM (R = 0.9), whereas the correlation between the two methods was poor in WM (R = 0.09). The rCBF in GM and WM and the GM/WM ratio obtained using DPC were consistent with the literature values assessed using 15 O-H2 O PET. The rCBF value obtained using DPC was significantly higher in the GM and WM than that using ASL. DATA CONCLUSION: DPC enabled noninvasive quantification of rCBF. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 1.

Changes in Apparent Diffusion Coefficient (ADC) during Cardiac Cycle of the Brain in Idiopathic Normal Pressure Hydrocephalus Before and After Cerebrospinal Fluid Drainage.

BACKGROUND: The causative mechanisms of idiopathic normal-pressure hydrocephalus (iNPH) symptoms are currently unknown. PURPOSE: To assess the dynamic changes in the apparent diffusion coefficient (ADC) during the cardiac cycle (ΔADC) of the brain before and after the lumbar tap and shunt surgery for the purpose of determining changes in hydrodynamic and biomechanical properties in the brain after cerebrospinal fluid (CSF) drainage for iNPH. STUDY TYPE: Retrospective. SUBJECTS: Overall, 22 patients suspected to have iNPH were examined before and after the lumbar tap and were divided into patients who showed symptomatic improvements (positive group, n = 17) and those without improvement (negative group, n = 5) after the lumbar tap. Seven patients in the positive group were examined after the shunt surgery. FIELD STRENGTH/SEQUENCE: 1.5T, electrocardiographically synchronized single-shot diffusion echo-planar imaging. ASSESSMENT: The frontal white matter ΔADC and mean ADC (ADCmean ) were compared between before and 24 hours after lumbar tap and from 1 week to 1 month after the shunt surgery. STATISTICAL TESTS: Wilcoxon signed-rank test was used. P < 0.05 was considered statistically significant. RESULTS: The ΔADC after the lumbar tap in the positive group was significantly lower than that before (P < 0.05), whereas no significant difference was found in the negative group (P = 0.23). After the lumbar tap, ΔADC decreased in 16 of 17 patients in the positive group, whereas ADCmean did not significantly change (P = 0.96). After the shunt surgery, ΔADC decreased in all seven patients (P < 0.05), whereas ADCmean did not significantly change (P = 0.87). DATA CONCLUSION: The frontal white matter ΔADC in iNPH decreased after the lumbar tap and shunt surgery. ΔADC analysis may provide detailed information regarding changes in the hydrodynamic and biomechanical properties through CSF drainage. LEVEL OF EVIDENCE: 4. TECHNICAL EFFICACY STAGE: 4.

Analysis of risk factors for multidrug-resistant pathogens and appropriate treatment indications for pneumonia in children with neurologic impairment.

INTRODUCTION: The features of pneumonia in children with neurologic impairment (NI) resemble those of healthcare-associated pneumonia is defined as pneumonia occurring in the community associated with healthcare risk factors. There are currently no guidelines for the treatment of pneumonia in children with NI. Here, we assessed whether the guidelines applicable for treating pneumonia in adults could be applied to children with NI. METHODS: Between 2008 and 2019, we enrolled children with NI who developed pneumonia and were treated in the pediatric ward of Kawasaki Medical School Hospital. We evaluated patient characteristics, the frequency of isolation of multidrug-resistant (MDR) pathogens, and clinical outcomes. RESULTS: MDR pathogens were more frequently isolated from patients receiving tube feeding (TF) and/or with tracheostomy than from patients without these risk factors. Other risk factors, including a history of antibiotic therapy and methicillin-resistant Staphylococcus aureus isolation, recent hospitalization, residence in a nursing home or extended care facility, and low-dose, long-term macrolide therapy, did not significantly affect the frequency of MDR pathogen isolation. In patients receiving TF and/or with tracheostomy, treatment success was achieved in all cases treated with broad-spectrum antibiotics and 72.2% of cases treated with non-broad-spectrum antibiotics (P = 0.007). Conversely, among patients without these risk factors, no such difference was observed. CONCLUSIONS: Our findings indicate that the guideline to select antibiotics for treating pneumonia in children with NI should be simpler and more useful than the current guidelines for adult pneumonia, based on risk factor assessment for MDR pathogens.

Recent acute reduction in macrolide-resistant Mycoplasma pneumoniae infections among Japanese children.

INTRODUCTION: Mycoplasma pneumoniae contributes to numerous pneumonia cases among children and young adults. Therefore, this study aimed to investigate the prevalence of M. pneumoniae infections among Japanese children, occurring since 2008. METHODS: Nasopharyngeal swab specimens were obtained from all cases, following which real-time PCR was performed to identify M. pneumoniae. Further, the p1 genotypes of isolates were determined using the PCR restriction fragment length polymorphism typing method. RESULTS: The annual rate of macrolide-resistant M. pneumoniae (MRMP) infections peaked at 81.8% in 2012 and decreased annually until 2015. Although the infection rate increased to 65.3% in 2016, it decreased again to 14.3% in 2018. Although >90% of isolates harbored the type 1 genotype until 2012, this rate decreased, and approximately 80% harbored p1 genotypes other than type 1 in 2018. Furthermore, the occurrence rate of MRMP among the type 1 isolates was very high (82.4%), whereas that among p1 genotypes other than type 1 was very low (6.5%). CONCLUSIONS: MRMP occurrence potentially decreased owing to changes in not only antibiotic usage but also in the distribution of p1 genotype among isolates.

Evaluation of gravity effect on inferior vena cava and abdominal aortic flow using multi-posture MRI.

BACKGROUND: Inferior vena cava flow (IVCF) and abdominal aortic flow (AAF) are essential components of the systemic circulation. Although postural changes might alter IVCF and AAF by the gravity effect, the exact details are unknown. PURPOSE: To evaluate the effect of gravity on IVCF and AAF using a novel magnetic resonance imaging (MRI) system that can image in any position. MATERIAL AND METHODS: Caval velocity-mapped images were obtained using the cine phase-contrast technique in the upright and supine positions with multi-posture MRI (n = 12). The mean IVCF/AAF velocity, maximum IVCF/AAF velocity, cross-sectional area of IVC/AA, mean IVCF/AAF, maximum IVCF/AAF, and heart rate in the two positions were assessed. RESULTS: The mean IVCF velocity, maximum IVCF velocity, cross-sectional area of IVC, mean IVCF, maximum IVCF, mean AAF velocity, maximum AAF velocity, mean AAF, and maximum AAF were significantly lower in the upright position compared with the supine position (P < 0.05 for all), with differences of 52% ± 33%, 36% ± 19%, 56% ± 18%, 26% ± 18%, 19% ± 11%, 33% ± 13%, 33% ± 22%, 42% ± 21%, and 37% ± 28%, respectively. Heart rate was significantly higher in the upright position compared with the supine position (116% ± 9.2%; P = 0.003). There were no differences in cross-sectional area of AA between the two positions (108% ± 22%; P = 0.583). CONCLUSION: The effect of gravity decreases IVCF and AAF. Clarifying the effect of gravity on IVCF and AAF during a postural change may help to improve the management of patients with circulatory disease.

Epidemiology of urinary tract infections in children: Causative bacteria and antimicrobial therapy.

BACKGROUND: Urinary tract infections (UTIs) are the most common bacterial infections in children. This study aimed to review characteristics of causative bacteria and the effectiveness of antimicrobial therapy in children with febrile UTIs. METHODS: Clinical records of 108 patients (130 episodes) with febrile UTIs admitted to the Kawasaki Medical School Hospital between July 2009 and October 2016 were retrospectively reviewed. The characteristics of the causative bacteria, antibacterial therapy, and therapeutic effect were verified. RESULTS: Patients were aged between 0 and 183 months (median age: 3 months). Seventy-three (67.6%) were males. Sixty-three episodes (48.5%) were diagnosed with complicated UTIs. Forty-seven episodes (36.2%) were observed in patients aged <3 months; 15 of them had complicated UTIs. Escherichia coli (E. coli) was the most common pathogen, followed by Enterococcus faecalis (E. faecalis). Blood cultures were positive in three episodes. Among the 130 episodes, 62 (47.7%) were treated with a combination of ampicillin and third-generation cephalosporins, followed by third-generation cephalosporins (31 episodes, 23.8%) and sulbactam sodium / ampicillin sodium (15 episodes, 11.5%). In case of patients with uncomplicated/complicated UTIs and patients aged <3 and ≥3 months, the most common pathogen was E. coli, followed by E. faecalis. There was no difference in therapeutic effects between "combination ampicillin and third-generation cephalosporins" and "third-generation cephalosporin monotherapy" administered for the treatment of UTIs caused by E. coli. CONCLUSIONS: Escherichia coli is the most common pathogen among pediatric UTIs. For antibacterial therapy, third-generation cephalosporin monotherapy is effective and may not require combination therapy with ampicillin.

Low prevalence of Chlamydia pneumoniae infections during the Mycoplasma pneumoniae epidemic season: Results of nationwide surveillance in Japan.

OBJECTIVE: Chlamydia pneumoniae and Mycoplasma pneumoniae are both common causes of atypical pneumonia. We conducted an annual national survey of Japanese children to screen them for C. pneumoniae infections during the M. pneumoniae epidemic season. METHODS: Nasopharyngeal swab specimens were collected from children aged 0-15 years with suspected acute lower respiratory tract infection due to atypical pathogens, at 85 medical facilities in Japan from June 2008 to March 2018. Specimens were tested for infection using real-time polymerase chain reaction assays. RESULTS: Of 5002 specimens tested, 1822 (36.5%) were positive for M. pneumoniae alone, 42 (0.8%) were positive for C. pneumoniae alone, and 20 (0.4%) were positive for both organisms. In children with C. pneumoniae infection, the median C. pneumoniae DNA copy number was higher in those with single infections than in those with M. pneumoniae coinfection (p = 0.08); however it did not differ significantly according to whether the children had received antibiotics prior to sample collection (p = 0.34). CONCLUSIONS: The prevalence of C. pneumoniae infection was substantially lower than that of M. pneumoniae infection during the study period. The change in prevalence of C. pneumoniae was not influenced by that of M. pneumoniae. Children with single C. pneumoniae infection are likely to have had C. pneumoniae infection, while those with coinfection are likely to have been C. pneumoniae carriers.

Investigation of extrusion of the medial meniscus under full weight-loading conditions using upright weight-loading magnetic resonance imaging and ultrasonography.

BACKGROUND: Meniscal morphology under full weight-loading conditions is currently unknown. This study aimed to evaluate extrusion in the medial meniscus between unloaded and upright-loaded conditions in healthy adults using upright magnetic resonance imaging (MRI) and ultrasonography and to investigate the relationship between MRI and ultrasonography in upright-loaded conditions. METHODS: Eighteen healthy adult volunteers (13 men and 5 women) participated in the study. MRI and ultrasonography were performed with patients in the supine, double-leg upright (DLU), and single-leg upright (SLU) positions. Medial, anterior, and posterior extrusions of the medial meniscus against the tibial edge were evaluated and compared across the three positions. Medial extrusion correlations between MRI and ultrasonography were examined. Demographic data and hip-knee-ankle (HKA) angles were measured and correlated with changes in the medial extrusion. The medial meniscal extrusions detected via MRI and ultrasonography were compared across the three positions. Correlations were examined using Pearson's correlation coefficients. RESULTS: Negative correlations were found between the change in medial extrusion of the medial meniscus and HKA angle (MRI: r = -0.52, ultrasonography: r = -0.51). Although no significant differences among the three conditions were observed for the anterior and posterior extrusions of the medial meniscus, the medial extrusion of the medial meniscus was significantly greater in DLU and SLU positions than that in the supine position for MRI and ultrasonography (P < 0.05). Positive correlations for the medial extrusion of the medial meniscus were found between MRI and ultrasonography in all three positions (supine: r = 0.74, DLU; r = 0.71, SLU; r = 0.61). CONCLUSIONS: Although no significant differences in anterior and posterior extrusions of the medial meniscus were seen across the studied positions, the medial meniscus was found to undergo significant medial extrusion during upright weight-loading conditions. The strong correlation between MRI and ultrasonography highlighted the usefulness of ultrasonography. LEVEL OF EVIDENCE: Level IV.

Morphological changes in the long axis of the lower leg muscles during isometric contraction in the sitting position.

[Purpose] To compare the changes in the muscle cross-sectional area (MCSA) along the long axis of the lower leg muscles at rest and during ankle plantar flexors isometric contraction and to obtain basic information regarding the movement of lower leg muscles during ankle plantar flexors contraction. [Participants and Methods] Sixteen healthy young female participants (20.9 ± 1.2 years) were asked to sit with their ankles in a neutral ankle position. Images were obtained at rest and during isometric contraction of the ankle plantar flexors using gravity magnetic resonance imaging. The MCSAs of the triceps surae and tibialis anterior were measured. [Results] The middle region of the soleus muscle had a lower MCSA on contraction than at rest. In addition, the medial head of the gastrocnemius had a lower MCSA on contraction than at rest in the distal quarter. Moreover, the tibialis anterior had a lower MCSA at rest than on contraction in the middle region. [Conclusion] The area to be used as an indicator and the movement to be induced differ depending on the muscle during isometric contraction of the triceps surae.

Comparing Antimicrobial Susceptibilities among Mycoplasma pneumoniae Isolates from Pediatric Patients in Japan between Two Recent Epidemic Periods.

We compared the antimicrobial susceptibility of Mycoplasma pneumoniae isolates from pediatric patients in Japan in 2011-2012 and 2015-2016, when epidemics occurred. The antimicrobial activity of macrolides and tetracyclines against M. pneumoniae infection tended to be restored in 2015-2016. There was no change in the antimicrobial activity of quinolones against M. pneumoniae infection.

Effect of gravity on portal venous flow: Evaluation using multiposture MRI.

BACKGROUND: Analysis of portal venous flow (PVF) is important when evaluating the severity and prognosis of liver disease. PVF might be altered by postural changes (ie, difference in the effects of gravity). PURPOSE: To evaluate the effect of gravity on PVF using a novel MRI system, which can obtain abdominal MRIs in both the supine and the upright positions. STUDY TYPE: Prospective self control. SUBJECTS: Twelve healthy young male volunteers. FIELD STRENGTH/SEQUENCE: Caval velocity-mapped images were obtained using the electrocardiography-triggered cine phase-contrast technique in the supine and upright positions with multiposture MRI (paired 0.4 T permanent magnets). ASSESSMENT: The mean PVF velocity in the region of interest in each cardiac phase was determined. A PVF curve in the cardiac cycle was also obtained from the PVF velocity multiplied by the cross-sectional area. The mean PVF velocity, maximum PVF velocity, cross-sectional area of the PV, mean PVF, maximum PVF, and heart rate in the supine and upright positions were assessed. STATISTICAL TESTS: Wilcoxon signed-rank tests were applied. P < 0.05 was considered statistically significant. RESULTS: The mean PVF velocity, maximum PVF velocity, cross-sectional area of the PV, mean PVF, and maximum PVF were all significantly lower in the upright position compared with the supine position (P = 0.002 for all), with differences of 42% ± 15%, 38% ± 12%, 60% ± 17%, 24% ± 11%, and 22% ± 9.3%, respectively. However, heart rate was significantly higher (116% ± 9.2%, P = 0.003) in the upright position compared with the supine position. DATA CONCLUSION: The effect of gravity during postural change from a supine to an upright position significantly decreases the PVF. Multiposture MRI allows acquisition of more detailed information on liver function. LEVEL OF EVIDENCE: 2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:83-87.