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Background Pulmonary MRI with ultrashort echo time (UTE) has been compared with chest CT for nodule detection and classification. However, direct comparisons of these methods' capabilities for Lung CT Screening Reporting and Data System (Lung-RADS) evaluation remain lacking. Purpose To compare the capabilities of pulmonary MRI with UTE with those of standard- or low-dose thin-section CT for Lung-RADS classification. Materials and Methods In this prospective study, standard- and low-dose chest CT (270 mA and 60 mA, respectively) and MRI with UTE were used to examine consecutive participants enrolled between January 2017 and December 2020 who met American College of Radiology Appropriateness Criteria for lung cancer screening with low-dose CT. Probability of nodule presence was assessed for all methods with a five-point visual scoring system by two board-certified radiologists. All nodules were then evaluated in terms of their Lung-RADS classification using each method. To compare nodule detection capability of the three methods, consensus for performances was rated by using jackknife free-response receiver operating characteristic analysis, and sensitivity was compared by means of the McNemar test. In addition, weighted κ statistics were used to determine the agreement between Lung-RADS classification obtained with each method and the reference standard generated from standard-dose CT evaluated by two radiologists who were not included in the image analysis session. Results A total of 205 participants (mean age: 64 years ± 7 [standard deviation], 106 men) with 1073 nodules were enrolled. Figure of merit (FOM) (

Since thoracic MR imaging was first used in a clinical setting, it has been suggested that MR imaging has limited clinical utility for thoracic diseases, especially lung diseases, in comparison with x-ray CT and positron emission tomography (PET)/CT. However, in many countries and states and for specific indications, MR imaging has recently become practicable. In addition, recently developed pulmonary MR imaging with ultra-short TE (UTE) and zero TE (ZTE) has enhanced the utility of MR imaging for thoracic diseases in routine clinical practice. Furthermore, MR imaging has been introduced as being capable of assessing pulmonary function. It should be borne in mind, however, that these applications have so far been academically and clinically used only for healthy volunteers, but not for patients with various pulmonary diseases in Japan or other countries. In 2020, the Fleischner Society published a new report, which provides consensus expert opinions regarding appropriate clinical indications of pulmonary MR imaging for not only oncologic but also pulmonary diseases. This review article presents a brief history of MR imaging for thoracic diseases regarding its technical aspects and major clinical indications in Japan 1) in terms of what is currently available, 2) promising but requiring further validation or evaluation, and 3) developments warranting research investigations in preclinical or patient studies. State-of-the-art MR imaging can non-invasively visualize lung structural and functional abnormalities without ionizing radiation and thus provide an alternative to CT. MR imaging is considered as a tool for providing unique information. Moreover, prospective, randomized, and multi-center trials should be conducted to directly compare MR imaging with conventional methods to determine whether the former has equal or superior clinical relevance. The results of these trials together with continued improvements are expected to update or modify recommendations for the use of MRI in near future.

Morphological evaluation of the lung is important in the clinical evaluation of pulmonary diseases. However, the disease process, especially in its early phases, may primarily result in changes in pulmonary function without changing the pulmonary structure. In such cases, the traditional imaging approaches to pulmonary morphology may not provide sufficient insight into the underlying pathophysiology. Pulmonary imaging community has therefore tried to assess pulmonary diseases and functions utilizing not only nuclear medicine, but also CT and MR imaging with various technical approaches. In this review, we overview state-of-the art MR methods and the future direction of: (1) ventilation imaging, (2) perfusion imaging and (3) biomechanical evaluation for pulmonary functional imaging.

Temporal bone trauma is frequently encountered in the emergency department. Technologic advances have enabled timely acquisition of thin-section images and multiplanar reconstructions such that temporal bone anatomy can be evaluated in great detail, with excellent delineation of fractures. The temporal bone is composed of a myriad of tiny structures, including many fissures and canals, that must be distinguished from true fractures. In addition, injury to important structures may result in serious complications such as hearing loss, dizziness, imbalance, perilymphatic fistula, cerebrospinal fluid leakage, facial nerve paralysis, and vascular injury. Structures that should be examined include the tympanic cavity and tegmen, the ossicular chain, the bony labyrinth, the facial canal, the internal carotid artery, the jugular foramen and venous sinuses, and the intracranial contents. Radiologists should be familiar with the anatomy of the temporal bone and be able to describe any pathologic findings and make suggestions to referring clinicians to guide management and determine the prognosis. The authors describe the typical CT and MRI appearances of temporal bone trauma, entities that mimic this injury and thus must be differentiated, and compulsory points for evaluating clinically relevant associated complications. Instruction is provided for acquiring the diagnostic skills necessary to report suggested injury status, complications, and likely sequelae to clinicians.©RSNA, 2020.

Quantitative analyses of gamma-ray accumulation in single-photon emission computed tomography (SPECT), and the evaluation of antiresorptive agent-related osteonecrosis of the jaw (ARONJ) have been reported recently. However, the relationship between the quantitative parameters calculated from SPECT and the detailed morphological changes observed in computed tomography (CT) remains unclear. This study aimed to investigate patients’ characteristics and morphological changes observed on CT, and their effects on the quantitative values in SPECT. From April 2017 to March 2019, patients diagnosed with ARONJ at our hospital were enrolled. The data obtained before September 2017 were reviewed retrospectively, and other data were collected prospectively. CT scans were evaluated for internal texture, sequestrum formation, periosteal reaction, cortical perforation, bone expansion, and pathological fracture. For quantitative assessment, the ratio of the maximum standardized uptake value (SUV) to the mean SUV in the temporal bone (rSUVmax) was calculated from SPECT images. The factors affecting rSUVmax were investigated by multiple regression analysis. The statistical significance level was set at α = 0.05. Overall, 55 lesions of 42 patients (median age and interquartile range, 75 [67–80 years], 27 female) were evaluated. Male sex (p = 0.007) and bilateral location (p

The coronavirus disease (COVID-19) pandemic has complicated the work of general physicians due to the vagueness of fever standards. Because of the high virulence of the causative virus, the disease is rapidly spreading worldwide, even reaching the rural areas in Japan. During the first wave of the pandemic, the Japanese government set the standard as a temperature of 37.5°C lasting for more than four days. However, after the government deleted this standard from its website, there was confusion in the medical institutions, as they struggled to set their fever standards. As a result, social fear might force healthcare professionals to bring down the standard for fever to increase the sensitivity and identify patients with COVID-19 more accurately. During the second wave, the fever standard was set at 37°C to enable high sensitivity. Subsequently, general physicians had to approach many people with temperatures higher than 37°C who came to the hospital seeking treatment for their symptoms or to visit their families. People seek to avoid contracting the COVID-19 infection for health-related and social reasons. When there is a possibility of healthcare professionals testing positive, hospitals may have to shut down and face criticism from society, as the mass media generally accuses these hospitals of mismanagement.

To demonstrate the utility of compressed sensing with parallel imaging (Compressed SPEEDER) and AiCE compared with that of conventional parallel imaging (SPEEDER) for shortening examination time and improving image quality of women's pelvic MRI.Thirty consecutive patients with women's pelvic diseases (mean age 50 years) underwent T2-weighted imaging using Compressed SPEEDER as well as conventional SPEEDER reconstructed with and without AiCE. The examination times were recorded, and signal-to-noise ratio (SNR) was calculated for every patient. Moreover, overall image quality was assessed using a 5-point scoring system, and final scores for all patients were determined by consensus of two readers. Mean examination time, SNR and overall image quality were compared among the four data sets by Wilcoxon signed-rank test.Examination times for Compressed SPEEDER with and without AiCE were significantly shorter than those for conventional SPEEDER with and without AiCE (with AiCE: p 0.0001, without AiCE: p 0.0001). SNR of Compressed SPEEDER and of SPEEDER with AiCE was significantly superior to that of Compressed SPEEDER without AiCE (vs. Compressed SPEEDER, p = 0.01; vs. SPEEDER, p = 0.009). Overall image quality of Compressed SPEEDER with AiCE and of SPEEDER with and without AiCE was significantly higher than that of Compressed SPEEDER without AiCE (vs. Compressed SPEEDER with AiCE, p 0.0001; vs. SPEEDER with AiCE, p 0.0001; SPEEDER without AiCE, p = 0.0003).Image quality and shorten examination time for T2-weighted imaging in women's pelvic MRI can be significantly improved by using Compressed SPEEDER with AiCE in comparison with conventional SPEEDER, although other sequences were not tested.

Large size and low dislocation density bulk gallium nitride (GaN) crystals were successfully grown by original acidic ammonothermal method SCAAT™ (Super Critical Acidic Ammonia Technology). It enabled us to obtain extremely high crystallinity true bulk GaN. In this article, 2-inch size non-polar m-plane GaN and nearly 4-inch size polar c-plane GaN were demonstrated. The dislocation and stacking fault density of m-plane GaN were in the range of 102 to 103 cm-2 and 0 to 5 cm-1, respectively. The full width at half maximum (FWHM) of X-ray rocking curve (XRC) on (10-12) plane was 6.4 arcsec. The dislocation density of c-plane GaN was in the range of 103 to 104 cm-2. The off-angle distribution of nearly 4-inch size c-plane GaN was ±0.006° in the span of 80 mm. The types of dislocations in the c-plane GaN were identified by transmission electron microscope (TEM) observation. Hydride vapor phase epitaxy (HVPE) growth on the SCAA™ c-plane seed was carried out and obtained 2-inch wafer. The crystallinity was comparable to SCAAT™ seed; FWHM of XRC was less than 10 arcsec and off-angle distribution was ±0.017°.

To directly compare the capability of compressed sensing (CS) and parallel imaging (PI) accelerated T2 FSE (Fast Spin Echo) sequence with PI for head and neck MR imaging.Thirty consecutive patients with various head and neck diseases (15 men and 15 women, mean age 53 ± 22 years) underwent MR imaging by PI with CS and by PI. Reduction factors were as follows: PI with CS, 3 and PI, 1.5. Examination times for PI with CS and PI were all recorded. For quantitative image quality assessment, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. For qualitative assessment, two investigators assessed overall image quality, artifacts and diagnostic confidence level using a 5-point scoring system, and final scores were determined by consensus of two readers. Mean examination time and all indexes were compared by means of paired t-test and Wilcoxon signed-rank test. Inter-observer agreement for each qualitative index was assessed in terms of kappa statistics.Mean examination time for PI with CS (83.5 ± 11.0 s) was significantly shorter than that for PI (173.0 ± 54.4 s, p 0.0001). SNR and CNR of PI with CS were significantly better than those with PI (mean SNR; 11.2 ± 3.6 vs 8.9 ± 2.6, median of CNR; 7.4 vs. 6.1, p 0.0001). All inter-observer agreements were assessed as significant and substantial (0.62 κ 0.81).PI with CS accelerated T2 weighted sequence performs equally well or even slightly better than its PI accelerated, conventional counterpart at reduced scan times in the context of head and neck MR imaging.

Fluid collections in the retropharyngeal space (RPS) result from a wide spectrum of diseases, including retropharyngeal abscess, cervical osteomyelitis, and calcific tendinitis of the longus colli muscle. These conditions should be managed by different specialties; beginning with care in the emergency room, physicians from orthopedics, pediatrics, otolaryngology, and oncology are in charge of the treatment. Since these diseases demonstrate similar fluid collections in the RPS on computed tomography (CT) and magnetic resonance imaging (MRI), the radiologist's diagnosis based on the characteristic imaging findings is very important to identify the primary disease. Also, since some of the diseases require immediate surgical intervention to avoid life-threatening mediastinitis or airway obstruction, radiologists must distinguish these diseases correctly and provide recommendations for their management to physicians. Understanding clinical features and imaging findings of these fluid collections in the RPS is crucial for the best care.

Single-center, single-arm, prospective time-series study.To assess the cost-effectiveness and improvement in quality of life (QOL) of percutaneous vertebroplasty (PVP).PVP is known to relieve back pain and increase QOL for osteoporotic compression fractures. However, the economic value of PVP has never been evaluated in Japan where universal health care system is adopted.We prospectively followed up 163 patients with acute vertebral osteoporotic compression fractures, 44 males aged 76.4±6.0 years and 119 females aged 76.8±7.1 years, who underwent PVP. To measure health-related QOL and pain during 52 weeks observation, we used the European Quality of Life-5 Dimensions (EQ-5D), the Rolland-Morris Disability Questionnaire (RMD), the 8-item Short-Form health survey (SF-8), and visual analogue scale (VAS). Quality-adjusted life years (QALY) were calculated using the change of health utility of EQ-5D. The direct medical cost was calculated by accounting system of the hospital and Japanese health insurance system. Cost-effectiveness was analyzed using incremental cost-effectiveness ratio (ICER): Δ medical cost/Δ QALY.After PVP, improvement in EQ-5D, RMD, SF-8, and VAS scores were observed. The gain of QALY until 52 weeks was 0.162. The estimated lifetime gain of QALY reached 1.421. The direct medical cost for PVP was ¥286,740 (about 3061 US dollars). Cost-effectiveness analysis using ICER showed that lifetime medical cost for a gain of 1 QALY was ¥201,748 (about 2154 US dollars). Correlations between changes in EQ-5D scores and other parameters such as RMD, SF-8, and VAS were observed during most of the study period, which might support the reliability and applicability to measure health utilities by EQ-5D for osteoporotic compression fractures in Japan as well.PVP may improve QOL and ameliorate pain for acute osteoporotic compression fractures and be cost-effective in Japan.

We report a case of ileal internal hernia through the foramen of Winslow into the lesser sac. Preoperative computed tomography (CT) demonstrated that the herniated ileum, which showed a closed-loop obstruction, was located behind the portal vein, and the vein was subsequently compressed and narrowed by the herniated ileum. We found that similar cases in the literature of Winslow's foramen hernias that caused portal vein compression; however, portal vein narrowing has not been described as a characteristic CT finding. The narrowed portal vein sign could be useful in diagnosing the hernia through the foramen of Winslow.

We propose a method to compute the restoring force characteristics and dissipated energy to detect damage level of viaducts for railways and highways, using only acceleration. The acceleration data were measured by accelerometers which were installed on the top and the bottom of the structures. Wireless sensor network is used to compute and collect the data. Using this system, the information of restoring force characteristic and dissipated energy can be created.

For rating unambiguous performance of a light-emitting semiconductor material, determination of the absolute quantum efficiency (AQE) of radiation, which is basically a product of internal quantum efficiency (IQE) and light-extraction efficiency, is the most delightful way. Here, we propose the use of omnidirectional photoluminescence (ODPL) spectroscopy for quantifying AQE of the near-band-edge (NBE) emission, in order to evaluate bulk GaN crystals and wafers. When the measurement was carried out in the air, the AQE showed a continuous decrease most likely due to the formation of extrinsic nonradiative recombination channels at the surface by photo-pumping. However, such an influence was suppressed by measuring ODPL in an inert ambient such as nitrogen or in vacuum. Consequently, AQE was revealed to depend on the photo-pumping density. The increase in AQE of the NBE emission caused by the increase in the excess carrier concentration was significant, indicating gradual saturation of nonradiative recombina...

On May 2001 Shizuoka prefecture announced the third estimation of disasters that could possibly be caused by Tokai Earthquake. Some social conditions have changed and earthquake resistance buildings have been developed since 1993 when the previous estimation was studied. 1, 400 billion yen, for example, has been invested to prepare against earthquake disasters. The new damage estimation methods were developed after studying the great Hanshin-Awaji (Kobe) earthquake, and this study contributed to improvement of methods to predict disasters.Ishibashi's model in 1976 and the Central Disaster Prevention Council model in 1978 were combined for the new estimation. The Western part of Shizuoka prefecture was predicted to be more intensive than in the previous estimation.Disasters caused by earthquakes depend on the time it occurrs. In the study disasters were estimated in 8 cases such as 5 am in the winter, noon in the spring or in the fall, and 6 pm in the winter. These cases also included whether people were notified in advance or not. As a result, it was discoverd that the worst disaster would ocurr at 5 am in the winter when most people were sleeping in their beds, the same as in the Kobe Earthquake. 5, 851 lives would be lost in the disaster.To further prepare for an earthquake, it is important to return to the basic concept of disaster countermeasures, to fix the target of countermeasure implementation, to announce the result of the estimation to the public, and to reflect the disaster scenario in local disaster countermeasure plans.

Omnidirectional photoluminescence (ODPL) measurement using an integrating sphere was carried out to absolutely quantify the quantum efficiency of radiation ( η) in high quality GaN single crystals. The total numbers of photons belonging to photoluminescence (PL photons) and photons belonging to an excitation source (excitation photons) were simultaneously counted in the measurement, and η was defined as a ratio of the number of PL photons to the number of absorbed excitation photons. The ODPL spectra near the band edge commonly showed a two-peak structure, which originates from the sharp absorption edge of GaN. A methodology for quantifying internal quantum efficiency ( ηint) from such experimentally obtained η is derived. A record high ηint of typically 15% is obtained for a freestanding GaN crystal grown by hydride vapor phase epitaxy on a GaN seed crystal synthesized by the ammonothermal method using an acidic mineralizer, when the excitation photon energy and power density were 3.81 eV and 60 W/cm2, r...

Fundamental electronic and optical properties of a low-resistivity m-plane GaN single crystal, which was grown by hydride vapor phase epitaxy on a bulk GaN seed crystal synthesized by the ammonothermal method in supercritical ammonia using an acidic mineralizer, were investigated. The threading dislocation and basal-plane staking-fault densities of the crystal were around 104 cm−2 and less than 100 cm−1, respectively. Oxygen doping achieved a high electron concentration of 4 × 1018 cm−3 at room temperature. Accordingly, a photoluminescence (PL) band originating from the recombination of hot carriers was observed at low temperatures, even under weak excitation conditions. The simultaneous realization of low-level incorporation of Ga vacancies (VGa) less than 1016 cm−3 was confirmed by using the positron annihilation technique. Consistent with our long-standing claim that VGa complexes are the major nonradiative recombination centers in GaN, the fast-component PL lifetime of the near-band-edge emission at room temperature longer than 2 ns was achieved.

In this paper, we discusse the origin of basal-plane stacking faults (BSFs) generated in the homoepitaxial hydride vapor phase epitaxy (HVPE) growth of m-plane gallium nitride (GaN). We investigated the effects of seed quality, especially dislocation density, on BSF generation during homoepitaxy. The results clearly identify basal-plane dislocation in the seed as a cause of BSF generation. We realized high-quality m-plane GaN substrates with a 2-in. diameter using HVPE on low-dislocation-density m-plane seeds.

A wireless sensor network system for automatic diagnosis of damage level of structures under strong seismic loading is presented in this paper. Restoring force characteristics and dissipated energy of the structures under strong seismic loading can be computed on sensor node using measured acceleration data. The acceleration data are measured by accelerometers installed on the top and the bottom of the structures. Wireless sensor network is used to compute and collect the data. Using this system, the information of restoring force characteristic and dissipated energy can be created on-board.

An m-plane freestanding GaN substrate satisfying both low resistivity (ρ = 8.5 × 10−3 Ωcm) and a low point-defect concentration, being applicable to vertically conducting power-switching devices, was grown by hydride vapor phase epitaxy on a nearly bowing-free bulk GaN seed wafer synthesized by the ammonothermal method in supercritical ammonia using an acidic mineralizer. Its threading dislocation and basal-plane staking-fault densities were approximately 104 cm−2 and lower than 100 cm−1, respectively. A record-long fast-component photoluminescence lifetime of 2.07 ns at room temperature was obtained for the near-band-edge emission, reflecting a significantly low concentration of nonradiative recombination centers composed of Ga vacancies.

Local excitation and emission dynamics of an isolated “Type-I1” basal-plane stacking-fault (BSF) in very low dislocation density GaN were studied using spatio-time-resolved cathodoluminescence. The low temperature lifetime of the BSF emission was quantified to be 640 ps. The carrier diffusion length was estimated by observing the temporal delay of the BSF peak relative to the free-exciton signal as a function of distance from the BSF. The results indicate that the near-band-edge emission leads to subsequent optical excitation of the BSF that increases the apparent diffusion length. Limiting the observation volume can improve the spatial resolution.

In mammography units, the X-ray tube focal spot is located directly above the chest wall edge of the detector. Therefore, the X-ray beam is incident at a different angle along the cathode-anode axis. When the X-ray beam is incident on the imaging plate (IP) at a relatively large angle, the resolution property of a new imaging plate with dual-sided reading system would be degraded compared with the conventional imaging plate because of the parallax effect, which produces a shift in the image on two sides of the imaging plate. To evaluate the oblique incidence effect of the X-ray beam on the degradation of resolution properties and detection of simulated microcalcifications of a new CR system with a pixel size of 50 microm, its basic imaging properties and observer performance tests were compared with those of a conventional CR system. The resolution properties were evaluated by measuring modulation transfer functions (MTFs). Observer performance tests were conducted to compare the detectability of simulated microcalcifications of CR systems. Degradation of presampling MTFs for the new system is greater than that of the conventional CR system when the X-ray beam was incident at the same angle on the imaging plate. We found that the degradation of the area under the ROC curve (Az) for the new CR system was greater than that of the conventional CR system when the X-ray beam was incident at the same angle on the imaging plate.

Structural and optical qualities of half-a-μm-thick m-plane Al1−xInxN epilayers grown by metalorganic vapor phase epitaxy were remarkably improved via coherent growth on a low defect density m-plane freestanding GaN substrate prepared by hydride vapor phase epitaxy. All the epilayers unexceptionally suffer from uniaxial or biaxial anisotropic in-plane stress. However, full-width at half-maximum values of the x-ray ω-rocking curves were nearly unchanged as the underlayer values being 80 ∼ 150 arc sec for ( 101¯0) and ( 101¯2) diffractions with both ⟨0001⟩ and ⟨112¯0⟩ azimuths, as long as pseudomorphic structure was maintained. Such Al1−xInxN epilayers commonly exhibited a broad but predominant luminescence peak in ultraviolet (x ≤ 0.14) to green (x = 0.30) wavelengths. Its equivalent value of the internal quantum efficiency at room temperature was as high as 67% for x = 0.14 and 44% for x = 0.30. Because its high-energy cutoff commonly converged with the bandgap energy, the emission peak is assigned to ori...