Published papers

Hereby inviting young rising stars in chest radiology in Japan for contributing what they are working currently, we would like to show the potentials and directions of the near future research trends in the research field. I will provide a reflection on my own research topics. At the end, we also would like to discuss on how to choose the themes and topics of research: What to do or not to do? We strongly believe it will stimulate and help investigators in the field.

INTRODUCTION: Bronchiectasis, closely associated with nontuberculous mycobacterial pulmonary disease (NTM-PD), exhibits unevenly distributed lesions, yet their spatial features remain unclear. We hypothesized that upright CT, which may better depict distal airways due to gravity-induced lung expansion, might more accurately reflect disease severity and its relationship with pulmonary function tests (PFTs). METHODS: In this prospective study, twenty patients underwent low-dose inspiratory and expiratory CT scans in standing and supine positions. Airways were segmented with Vincent® software and classified as bronchiectatic or non-bronchiectatic. Generation-specific quantitative CT (QCT) parameters, including inspiratory airway total area (ITA), inspiratory airway lumen area (ILA), wall thickness, and wall area percentage (WA%), were measured and correlated with PFTs. RESULTS: Bronchiectatic lesions were primarily identified in the 8th-10th generation airways (anatomically the 7th-9th generations), the transition from distal bronchi to proximal bronchioles. Standing CT detected more distal airways than supine CT. Mixed-effect models revealed significantly larger ITA and higher WA% in bronchiectatic airways (8th-10th generations) on standing CT. In non-bronchiectatic airways (trachea to 6th generation), ITA and ILA were significantly larger in the standing position, except for the main bronchus ITA. ITA, ILA, and WA% were moderate to strongly correlated with %FVC, %FEV1, and FEF25-75%, reflecting airway obstruction, with stronger correlations in the standing position. ITA in bronchiectatic airways was moderately negatively correlated with diffusing capacity of the lungs for carbon monoxide, indicating potential alveolar disease. CONCLUSION: Upright CT offers useful structural biomarkers associated with airflow limitation and possible alveolar impairment in bronchiectasis with NTM-PD. REGISTRATION: University Hospital Medical Information Network (UMIN 000026587). URL: https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000030456.

© 2017, The Japanese Society of Nuclear Medicine. Purpose: Apical wall thickening with an “ace-of-spades” configuration is a unique sign of apical hypertrophic cardiomyopathy (AHCM). We investigated spade-shaped FDG uptake around the left ventricular apex (SSUA) incidentally found in routine oncological FDG PET. Methods: Cases showing SSUA were selected based on retrospective review. The pattern or intensity of SSUA was compared with the results of electrocardiogram (ECG), echocardiography, and stress myocardial perfusion SPECT. The diagnosis of ACHM was based on the presence of giant negative T wave in ECG, thickness of spade-shaped hypertrophy in the apex in echocardiography, and increased tracer uptake in the apex in rest SPECT. Results: Among the 34 patients in 36 PET scans showing SSUA, SSUA was weak in 17 and intense in 17. There were isolated SSUA (n = 29) and SSUA with diffuse or other focal left ventricular uptake (n = 5). Three patients with the latter uptake pattern turned out to have coexistence of AHCM and asymmetric septal hypertrophy. Of the 16 SSUA-positive patients who underwent echocardiography, 13 (81%) were diagnosed as AHCM and the remaining 3 were regarded as borderline AHCM (apical wall thickness, 14–15 mm). There were 16 patients with SSUA who also underwent PET scans after the study period among which 11 (69%) had persistent SSUA in the follow-up PET. In the remaining 5, follow-up PET scans showed diffuse left ventricular uptake and SSUA was barely visible. The intensity of SSUA was significantly or marginally associated with giant negative T wave (p < 0.01), apical asynergy (p = 0.08), and impaired coronary flow reserve (p < 0.05). There were no other factors correlated with the pattern or intensity of SSUA. Conclusion: SSUA incidentally found in oncological FDG PET appeared to be associated with AHCM, especially in ischemic conditions. The moderate repeatability of SSUA was probably due to obscurity by physiological uptake.

INTRODUCTION AND HYPOTHESIS: This study was aimed at comparing pelvic floor parameters between the standing and supine positions using upright computed tomography (CT) and evaluating the effects of sex and age in normal healthy volunteers. METHODS: In total, 139 volunteers (70 men, mean 46.7 years; 69 women, mean 47.3 years) underwent both upright CT in the standing position and conventional CT in the supine position. The distances from the bladder neck to the pubococcygeal line (PCL) and anorectal junction (ARJ), defined as the posterior aspect of the puborectalis muscle, to PCL were measured. The length, width, and area of the levator hiatus (LH) were measured on oblique axial images. RESULTS: The bladder neck (men, 22.2 ± 4.9 mm vs 28.3 ± 5.3 mm; women, 9.0 ± 5.1 mm vs 19.0 ± 4.0 mm) and ARJ (men, -18.8 ± 5.5 mm vs -12.1 ± 5.1 mm; women, -20.0 ± 4.7 mm vs -11.2 ± 4.3 mm) were significantly lower in the standing position than in the supine position (all p < 0.0001). The LH area (men, 1,990 ± 380 mm2 vs 1,697 ± 329 mm2; women, 2,284 ± 344 mm2 vs 1,811 ± 261 mm2) was significantly larger in the standing position (both p < 0.0001). Differences in all parameters between the standing and supine positions were larger in women than in men. ARJ in women showed a significant tendency to descend with age only in the standing position (r = -0.29, p = 0.017). CONCLUSIONS: The bladder neck and ARJ descend and the LH area enlarges in the standing position. Pelvic floor mobility is greater in women than in men. Descent of the ARJ in the standing position is associated with aging in women.

Limited data exist with regard to the outcome of the Nuss procedure for pectus excavatum repair in adults. Here, we analysed changes in lung capacity and thoracic morphology based on computed tomography (CT) imaging in adults with pectus excavatum before surgery, during bar insertion and after bar removal. Patients who underwent the Nuss procedure for pectus excavatum after the age of 20 were included in this study. Chest CT scans of the included participants were taken before the Nuss procedure, immediately before removal of the pectus bar and 6 months after removal of the pectus bar. Lung capacity and thoracic morphology measurements were made from the CT scans. Six patients aged 24-43 years were included in this study. After the Nuss procedure, lung capacity was decreased in all patients. Although the pectus bar was removed, lung capacity had not significantly increased and was almost the same volume as before the Nuss procedure. After the Nuss procedure, the funnel chest shape had improved in all cases, patients' thoracic spine had also moved forward as the thorax moved forward and patients' stoop had improved. Despite a lack of change in lung capacity, surgical modification should be considered to reduce stress on the thoracic spine and in turn, reduce pain in patients with pectus excavatum. However, further long-term observation seems necessary.

The severe shortage of donor hearts hampered the cardiac transplantation to patients with advanced heart failure. Therefore, cardiac regenerative therapies are eagerly awaited as a substitution. Human induced pluripotent stem cells (hiPSCs) are realistic cell source for regenerative cardiomyocytes. The hiPSC-derived cardiomyocytes are highly expected to help the recovery of heart. Avoidance of teratoma formation and large-scale culture of cardiomyocytes are definitely necessary for clinical setting. The combination of pure cardiac spheroids and gelatin hydrogel succeeded to recover reduced ejection fraction. The feasible transplantation strategy including transplantation device for regenerative cardiomyocytes are established in this study.

BACKGROUND: The classification of knee osteoarthritis is an essential clinical issue, particularly in terms of diagnosing early knee osteoarthritis. However, the evaluation of three-dimensional limb alignment on two-dimensional radiographs is limited. This study evaluated the three-dimensional changes induced by weight-bearing in the alignments of lower limbs at various stages of knee osteoarthritis. METHODS: Forty five knees of 25 patients (69.9 ± 8.9 years) with knee OA were examined in the study. CT images of the entire leg were obtained in the supine and standing positions using conventional CT and 320-row detector upright CT, respectively. Next, the differences in the three-dimensional alignment of the entire leg in the supine and standing positions were obtained using 3D-3D surface registration technique, and those were compared for each Kellgren-Lawrence grade. RESULTS: Greater flexion, adduction, and tibial internal rotation were observed in the standing position, as opposed to the supine position. Kellgren-Lawrence grades 1 and 4 showed significant differences in flexion, adduction, and tibial internal rotation between two postures. Grades 2 and 4 showed significant differences in adduction, while grades 1 and 2, and 1 and 3 showed significant differences in tibial internal rotation between standing and supine positions. CONCLUSIONS: Weight-bearing makes greater the three-dimensional deformities in knees with osteoarthritis. Particularly, greater tibial internal rotation was observed in patients with grades 2 and 3 compared to those with grade 1. The greater tibial internal rotation due to weight-bearing is a key pathologic feature to detect early osteoarthritic change in knees undergoing osteoarthritis.

BACKGROUND: For knee osteoarthritis (OA) treatment, it is important to correct the lower limb alignment including the foot. However, in the upright position, lower limb alignment is generally assessed from the body surface or radiographs, and it is a challenge to capture the exact characteristics of three-dimensional lower limb alignment. The purpose of the study was to measure lower limb alignment in patients with knee OA using upright computed tomography (CT) and radiography, and to identify features of knee joint deformity. METHODS: A total of 45 limbs in 25 patients with knee OA were enrolled. The subjects underwent both upright CT and radiography for the whole lower limb in the standing position. The joint angles were calculated on both images. The degree of knee OA was classified according to Kellgren-Lawrence (KL) grade by referring to radiography, which is mainly based on the degree of articular cartilage loss and severity of osteophytes, and the characteristics or correlation between knee and ankle joint in each group was investigated. RESULTS: In KL-I, there was an association between varus of the knee joint and internal rotation of the talocrural joint (r = 0.76, P < 0.05). In KL-II, there was an association between varus of the knee joint and eversion of the subtalar joint (r = 0.63, P < 0.05) and talocrural joint (r = - 0.65, P < 0.05). In KL-III, there was an association between varus of the knee joint and internal rotation of the subtalar joint (r = - 0.62, P < 0.05), and in KL-IV, there was an association between varus of the knee joint and internal rotation of the subtalar joint (r = - 0.58, P < 0.05). CONCLUSIONS: The lower limb alignment of patients with knee OA in the standing position was found that as knee OA worsened, it became apparent that compensatory knee joint alignment depended on the ankle joint rather than the subtalar joint. The results may help in the rehabilitation of patients with knee OA, since the ankle joint alignment has a significant impact on the knee joint during coarse movements involving load.

Background Subclinical leaflet thrombosis, characterized by hypoattenuated leaflet thickening (HALT) on multidetector computed tomography, is common after transcatheter aortic valve replacement (TAVR). Because little is known about the long-term natural history of subclinical HALT, we aimed to investigate this in patients who underwent TAVR without using additional anticoagulation. Methods and Results We retrospectively evaluated patients who underwent TAVR with the Edwards SAPIEN-XT at our institute between October 2013 and December 2015. Patients were grouped according to the presence or absence of HALT within 1 year after TAVR (HALT and No-HALT groups). The primary outcome, defined as the composite of all-cause mortality, heart failure readmission, and ischemic stroke, was compared. Valve performance was assessed over time by transthoracic echocardiography. Among 124 patients (men: 29.1%; median age, 85 years), 27 (21.8%) showed HALT on multidetector computed tomography within 1 year after TAVR. No patient required additional anticoagulation for treating HALT because of the absence of valve-related symptomatic deterioration. During the median follow-up period of 4.7 years (interquartile range, 4.0-5.6), the rate of primary outcome and valve performance was not statistically different between the 2 groups (37.0% versus 38.1%; log-rank test P=0.92; mean pressure gradient, 9 mm Hg [8-14 mm Hg] versus 10 mm Hg [7-15 mm Hg]; P=0.51, respectively). Conclusions Approximately 20% of patients after TAVR had HALT within 1 year; however, that did not change the risk of subsequent adverse cardiovascular events or the valve performance with statistical significance for up to 5 years despite no additional anticoagulation therapy.

BACKGROUND: The rotational motion of the spine plays a crucial role in daily activities. Understanding the mechanisms of spinal rotation is essential for evaluating normal spinal function, especially in standing positions due to the influence of gravity. However, previous studies on spinal rotation have been limited. RESEARCH QUESTION: What are the differences in thoracolumbar rotation during trunk rotation in a standing position among different age and gender groups? METHODS: This cross-sectional study involved 49 healthy volunteers without back pain, including 24 younger participants (13 males, 11 females) and 25 elderly participants (12 males, 13 females). Upright and trunk-rotated CT (right-rotated standing positions) scans were taken. Vertebral rotation was measured using the femoral head center as an axis. RESULTS: Analysis of spinal alignment in the standing position revealed mild rotation from the lumbar to thoracic vertebrae. The lumbar spine exhibited left rotation at apex of L3 (L3: -1.3±3.8°, p=0.01), while the lower thoracic spine showed right rotation at apex of T8 (T8: 1.9±2.4°, p<0.001) and the upper thoracic spine showed left rotation at apex of T3 (T3: -2.6±2.9°, p<0.001). The lumbar spine showed minimal rotation during maximum trunk rotation, with significant rotation noted above T10 (16 % vs 84 %). The total thoracolumbar spinal rotation at T1 showed significant differences by gender and age (male vs. female: 23.9±° vs. 30.3±°, p=0.001; young vs. elderly: 29.2±° vs. 25.0±°, p=0.028; elderly male vs. elderly female: 19.2±° vs. 30.4±°, p<0.001). Younger participants did not show significant gender differences, while elderly females retained more rotation compared to males. SIGNIFICANCE: This pioneering study provides the first detailed report on the range of spinal rotation in a physiological standing situation, highlighting significant differences by gender and age. These findings offer new insights into the natural patterns of spinal rotation and their potential implications for diagnosing and treating spinal disorders.

BACKGROUND: Hypoattenuated leaflet thickening (HALT) after transcatheter aortic valve implantation (TAVI) detected on multidetector computed tomography (MDCT) is considered leaflet thrombosis. However, its impact on long-term clinical outcomes remains unclear. This study aimed to investigate the impact of early HALT detection after TAVI on long-term clinical outcomes and structural valve deterioration beyond 6 years. METHODS: Of the 672 consecutive patients who underwent TAVI between 2013 and 2018, 448 were treated with either SAPIEN XT or SAPIEN 3 and underwent MDCT analysis within 30 days after TAVI. MDCT results and echocardiographic data were analyzed annually. RESULTS: HALT was detected in 68 (15.2%) of 448 eligible patients within 30 days after TAVI. No significant difference in effective orifice area was observed by echocardiography within 30 days after TAVI between the HALT and the non-HALT groups in SAPIEN XT (HALT vs. non-HALT: 1.62 ± 0.66 cm2 vs. 1.72 ± 0.43 cm2; p = 0.26) and in SAPIEN 3 (1.42 ± 0.35 cm2 vs. 1.45 ± 0.34 cm2; p = 0.63). No significant differences in all-cause mortality (52.9% vs. 60.0%; hazard ratio (HR): 1.19; 95% confidence interval (CI): 0.83-1.70; p = 0.3), stroke incidence (5.9% vs. 7.1%; HR: 1.06; 95% CI: 0.08-13.7; p = 0.97), heart failure rehospitalization (10.3% vs. 15.0%; HR: 2.3; 95% CI: 0.89-5.99; p = 0.09), and structural valve deterioration (14.7% vs. 17.9%; HR: 0.89; 95% CI: 0.45-1.73; p = 0.73) were observed between the HALT and the non-HALT groups during the median follow-up of 1872 (interquartile range; 1203-2468) days. CONCLUSIONS: HALT within 30 days was not associated with clinical outcomes or hemodynamic performance during long-term follow-up.

This review provides key insights into sacroiliitis imaging, covering anatomy, imaging techniques, and interpretation. It focuses on normal physiological changes in young to middle-aged women, children, and the elderly that can resemble sacroiliitis. We emphasize the importance of distinguishing between active and structural lesions, as highlighted in the recent ASAS-SPARTAN standardized magnetic resonance imaging protocol. Physicians should be aware that bone marrow oedema signals on magnetic resonance imaging, a hallmark of active inflammation in axial spondyloarthritis, can also be observed in young to middle-aged women, especially postpartum, even without spondyloarthritis. Paediatric sacroiliac joints may show changes mimicking inflammation due to ongoing bone growth. Furthermore, degenerative changes in the sacroiliac joint are common with advancing age and can be mistaken for sacroiliitis or interpreted as structural changes. The presence of accessory sacroiliac joints, prone to degeneration, further complicates diagnosis. Accurate interpretation requires considering these normal variations to avoid misdiagnosing spondyloarthritis. Collaboration between clinicians and radiologists is crucial, especially when encountering atypical or clinically inconsistent findings.

BACKGROUND: Coronal wedge insoles are commonly prescribed to mitigate musculoskeletal disorders, yet their static-standing kinematic and kinetic effects on lower extremity joints remain insufficiently understood. METHODS: This cross-sectional experimental study included 15 healthy older adults (mean 64.9 ± 6.0 y; 11 females, 4 males) who underwent CT imaging of the entire lower limbs during static standing. Ground reaction forces (GRFs) were simultaneously recorded using right and left force plates, with their sum equal in magnitude and opposite in direction to the body weight vector. Three floor conditions were tested: a 10-degree medial wedge, a flat surface, and a 10-degree lateral wedge. Lower limb alignment, GRF vector inclinations, projected GRF location at the height of the joint center, and external joint moments were assessed under 3 floor conditions. RESULTS: Coronal wedges altered hip and subtalar joint angles, with medial wedges inducing hindfoot supination and hip abduction, whereas lateral wedges promoted hindfoot pronation and hip internal rotation. The GRF vector was found to generally pass lateral to the tibiotalar and subtalar joints and medial to the hip joint, generating eversion and adduction moments, respectively. Notably, these moments increased on the lateral wedge but were reduced on the medial wedge. In contrast, projected GRF location at joint height remained near the knee joint center across all conditions, resulting in minimal varus/valgus knee moments. CONCLUSION: This study provides the first quantifications of the 3-dimensional GRF vector concerning joint centers during static standing; these exploratory findings warrant confirmation during gait and in symptomatic cohorts. Our study suggests that lateral wedges tend to increase external joint moments at the hip and tibiotalar. Although further investigation is needed, these mechanical effects at the hip may have potential relevance and should be considered with caution when prescribing lateral wedge insoles.

© 2017 Elsevier B.V. Objectives To compare the image quality between virtual monochromatic spectral (VMS) images obtained using 320-row detector CT and polychromatic 120-kVp images reconstructed with or without iterative reconstruction using various phantom sizes. Materials and methods Torso phantoms simulating three patient sizes and containing four syringes filled with water or different contrast media (5, 10, 15 mgI/mL15 mgI/ml) were used. The phantoms were scanned using dual-energy (80/135-kVp) and single-energy (120-kVp) protocols at different settings (20 mGy, 12 mGy, and 6 mGy). VMS images were generated at 1-keV intervals (range, 35–135 keV). Both the VMS images and the single-energy 120-kVp images were reconstructed using filtered back projection (FBP) and adaptive iterative dose reduction 3D (AIDR-3D). The signal-to-noise ratio (SNR), and the contrast-to-noise ratio (CNR) were assessed. Results Using FBP reconstruction, the SNR and CNR of the VMS images were lower than or similar to those of the 120-kVp images for most dose settings. Using AIDR-3D reconstruction, however, the 70-keV VMS images had higher SNRs and CNRs than the 120-kVp images at most settings. Conclusions The image quality of VMS images with FBP reconstruction tended to be lower than that of the 120-kVp images. With the use of AIDR-3D, however, approximately 70-keV VMS images had a higher image quality than the 120-kVp images.

© 2017 Elsevier Ltd Background and objectives Pulmonary Mycobacterium avium complex (pMAC) disease manifests as various types of lesions, such as infiltrates, nodules, cavities, and bronchiectasis. However, the important determinants for clinical parameters in lung involvement are poorly understood. The objective of this study was to obtain quantitative parameters by 3-dimensional CT, and investigate the relationship between these parameters and the pulmonary function tests (PFTs) and health-related quality of life. Material and methods Quantitative analysis using CT was performed in 67 pMAC patients. The relationship between new quantitative parameters for evaluating lung involvement using 3-dimensional CT and PFTs or St George's Respiratory Questionnaire (SGRQ) was evaluated. Results The ratio of infiltration to total lung volume showed significant correlation with the PFT results, especially the percent-predicted forced vital capacity (%FVC; ρ = −0.52), residual volume (ρ = −0.51), and total lung capacity (ρ = −0.59). The cavity volume was strongly correlated with the %FVC (ρ = −0.78) in the cavity group, while the ratio of infiltration to total lung volume was strongly correlated with the %FVC (ρ = −0.53) in the non-cavity group. The ratio of infiltration to total lung volume was significantly correlated with all SGRQ parameters (ρ = 0.41–0.52) in the non-cavity group. Conclusions Infiltration was an important parameter for the PFTs and SGRQ in pMAC patients according to the 3-dimensional CT analysis. Moreover, cavity volume was an important parameter of the PFTs in the cavity group. Therefore, infiltration and cavity volume are key features for the management of pMAC disease.

Objectives: To evaluate how well the tonsils can be viewed, in addition to echogenicity, using ultrasound, and to compare these results between children younger and older than the age of 3. Methods: We evaluated the tonsils of 99 patients (72.0 ± 59.1 months) by ultrasound. Ultrasound scans of both the left and right side, in both the transverse and longitudinal planes, were obtained. Images were scored with one of four grades according to how well the tonsil border could be distinguished, 0 being the worst and 3 being the best. Grades 2 or 3 (>50% of the tonsil border was detectable) in both tonsils, in either the transverse or longitudinal image, were considered "evaluable." Echogenicity was designated as imperceptible, low echoic, or striated in appearance. Statistical analysis was performed using the Mann-Whitney U test. Results: Bilateral tonsils were evaluable in 96.0% (96/99) of cases. The mean grades were 2.44 ± 0.65/2.03 ± 0.68 in the right transverse/longitudinal images, and 2.40 ± 0.59/2.12 ± 0.73 in the left transverse/longitudinal images. The grades in children older than the age of 3 were significantly higher than those in younger patients (all P <.05). Echogenicity classification on the right and left side revealed a striated appearance in 97.0% (96/99) and 90.0% (89/99) of cases, respectively. Conclusions: The tonsils of almost all pediatric patients could be evaluated by ultrasound, particularly for patients older than 3 years. Additionally, a striated pattern of the tonsils was observed in most cases.

© 2017 Elsevier Inc. Complications after transcatheter aortic valve implantation (TAVI) remain an important issue. This study aimed to evaluate the impact of systematic postprocedural multidetector computed tomography (MDCT) to detect subclinical complications after TAVI. From October 2013 to August 2015, a total of 135 patients who underwent transfemoral TAVI (n = 116) or transapical TAVI (n = 19) with Sapien XT and MDCT preprocedure and postprocedure were enrolled. Postprocedural MDCT findings were compared with the preprocedural MDCT findings. Cardiovascular complications were observed in 25.9% of patients, including 6 cases (4.5%) with major complications. Of those, clinically apparent major complications were reported in 2 cases including rupture of the sinus of Valsalva and iliac rupture. The complications in the remaining 4 cases (3.0%) included aortic dissection, aortic intramural hematoma, and left ventricular apical pseudoaneurysm, which were totally asymptomatic and only detected by MDCT. The apical pseudoaneurysm required surgical repair. Minor complications were observed in 21.5% of patients, 50% of which were subclinical. Only 1 case with femoral pseudoaneurysm required an additional procedure. Noncardiovascular findings were detected in 27.4% of patients; the most frequent were pleural effusions and atelectasis, which were predominantly observed in those treated through a transapical approach. Contrast-induced acute kidney injury after postprocedural MDCT was reported in 1 patient whose clinical course was complicated by sepsis. In conclusion, postprocedural MDCT was useful in detecting important subclinical complications that may affect the clinical course without deterioration of renal function.