Publications by authors named "Atsuya Watanabe"

77 Publications

Interpretable and Lightweight 3-D Deep Learning Model For Automated ACL Diagnosis.

IEEE J Biomed Health Inform 2021 May 18;PP. Epub 2021 May 18.

We propose an interpretable and lightweight 3D deep neural network model that diagnoses anterior cruciate ligament (ACL) tears from a knee MRI exam. Previous works focused primarily on achieving better diagnostic accuracy but paid less attention to practical aspects such as explainability and model size. They mainly relied on ImageNet pre-trained 2D deep neural network backbones, such as AlexNet or ResNet, which are computationally expensive. Some of them tried to interpret the models using post-inference visualization tools, such as CAM or Grad-CAM, which lack in generating accurate heatmaps. Our work addresses the two limitations by understanding the characteristics of ACL tear diagnosis. We argue that the semantic features required for classifying ACL tears are locally confined and highly homogeneous. We harness the unique characteristics of the task by incorporating: 1) attention modules and Gaussian positional encoding to reinforce the seeking of local features; 2) squeeze modules and fewer convolutional filters to reflect the homogeneity of the features. As a result, our model is interpretable: our attention modules can precisely highlight the ACL region without any location information given to them. Our model is extremely lightweight: consisting of only 43K trainable parameters and 7.1G of Floating-point operations per second (FLOPs), that is 225 times smaller and 91 times lesser than the previous state-of-the-art, respectively. Our model is accurate: our model outperforms the previous state-of-the-art with the average ROC-AUC of 0.983 and 0.980 on the Chiba and Stanford knee datasets, respectively.
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http://dx.doi.org/10.1109/JBHI.2021.3081355DOI Listing
May 2021

Usefulness of Simultaneous Magnetic Resonance Neurography and Apparent T2 Mapping for the Diagnosis of Cervical Radiculopathy.

Asian Spine J 2021 May 20. Epub 2021 May 20.

Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.

Study Design: Retrospective observational study.

Purpose: We investigated the correlation between T2 relaxation times and clinical symptoms in patients with cervical radiculopathy caused by cervical disk herniation.

Overview Of Literature: There are currently no imaging modalities that can assess the affected cervical nerve roots quantitatively.

Methods: A total of 14 patients with unilateral radicular symptoms and five healthy subjects were subjected to simultaneous apparent T2 mapping and neurography with nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation enhancement signaling (SHINKEI-Quant) using a 3-Tesla magnetic resonance imaging. The Visual Analog Scale (VAS) score for neck pain and upper arm pain was used to evaluate clinical symptoms. T2 relaxation times of the cervical dorsal root ganglia of the brachial plexus were measured bilaterally from C4 to C8 in patients with radicular symptoms and from C5 to C8 in healthy controls. The T2 ratio was calculated as the affected side to unaffected side.

Results: When comparing nerve roots bilaterally at each spinal level, no significant differences in T2 relaxation times were found between patients and healthy subjects. However, T2 relaxation times of nerve roots in the patients with unilateral radicular symptoms were significantly prolonged on the involved side compared with the uninvolved side (p<0.05). The VAS score for upper arm pain was not significantly correlated with the T2 relaxation times, but was positively correlated with the T2 ratio.

Conclusions: In patients with cervical radiculopathy, the SHINKEI-Quant technique can be used to quantitatively evaluate the compressed cervical nerve roots. The VAS score for upper arm pain was positively correlated with the T2 ratio. This suggests that the SHINKEI-Quant is a potential tool for the diagnosis of cervical nerve entrapment.
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http://dx.doi.org/10.31616/asj.2020.0668DOI Listing
May 2021

Skip decompression surgeries in the treatment of holospinal epidural abscess: a case report.

Spinal Cord Ser Cases 2021 May 13;7(1):38. Epub 2021 May 13.

Department of Orthopaedic Surgery, Toho University Sakura Medical Center, Sakura, Japan.

Introduction: Holospinal epidural abscess (HEA) extending from the cervical to the lumbosacral spine is an extremely rare condition. Surgical treatment of HEA, which involves extensive decompression of the spinal lesion is difficult in emergency settings. However, the authors successfully treated a case of HEA in critical condition with severe neurological deficits through a combination of skip decompression surgeries and catheter irrigation.

Case Presentation: A 73-year-old man complained of neck and back pain and developed muscle weakness in the upper and lower extremities (C5 AIS D tetraplegia). When he was transferred to our hospital, a marked increase in leukocytes (13330/μL) and C-reactive protein levels (32.11 mg/dL) was observed. Magnetic resonance imaging (MRI) revealed a HEA extending from C1 to S2 levels. Therefore, an emergency posterior decompression on C4-5 and T4-7 was performed, followed by catheter irrigation using a venous catheter. Blood and intraoperative isolated microorganisms were identified as Streptococcus intermedius, which is a rare cause of spinal infection. He experienced marked improvement in pain after surgery. Two months after surgery, the epidural abscess completely disappeared. Motor weakness gradually improved, and he was able to walk without support and showed no pain recurrence during the final follow-up (20 months after surgery).

Discussion: Early diagnosis is important for the treatment of HEAs. Therefore, a whole spine MRI is recommended when an extensive spinal epidural abscess is suspected. Decompression surgery at limited spine levels followed by catheter irrigation should be considered in patients with HEA.
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http://dx.doi.org/10.1038/s41394-021-00401-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8119455PMC
May 2021

[Effects of health literacy on frailty status at two-year follow-up in older adults: A prospective cohort study].

Nihon Ronen Igakkai Zasshi 2021 ;58(1):101-110

Center for Liberal Arts and Sciences, Faculty of Engineering, Toyama Prefectural University.

Aim: To investigate the longitudinal association between health literacy and frailty status at two-year follow-up in community-dwelling older adults.

Methods: A total of 218 older adults (mean age, 72.5±4.9 [range 65-86] years old; men, n=81) without frailty at baseline participated in this study. Functional health literacy was assessed using the Newest Vital Sign (NVS). Comprehensive health literacy was assessed using the 47-item European Health Literacy Survey Questionnaire (HLS-EU-Q47). Comprehensive health literacy indices are constructed as a general health literacy index comprising all items along with the three sub-indices of health care, disease prevention, and health promotion domains. Demographic data and other potential confounding factors were also assessed. The total Kihon checklist score was used to monitor the presence of frailty based on a score of ≥8 at the 2-year follow-up (postal survey).

Results: Of the 253 participants in the follow-up survey, 226 responded (response rate: 89.3%). Excluding the 8 participants with missing values, 25 (11.5%) of the 218 were reported to be frail. A multiple logistic regression analysis indicated that comprehensive health literacy (total score of HLS-EU-Q47) was independently associated with a lower risk of frailty (odds ratio per standard deviation = 0.54, 95% confidence interval = 0.33-0.87) after adjusting for the covariates (age, gender, education, body mass index, gait speed, cognitive function, and comorbidities). The health care and disease prevention domain scores of the HLS-EU-Q47 were also independently associated with a lower risk of frailty. Functional health literacy (NVS score) was not associated with frailty.

Conclusions: Older adults with higher comprehensive health literacy are less likely to be frail at two-year follow-up than those with a lower literacy.
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http://dx.doi.org/10.3143/geriatrics.58.101DOI Listing
February 2021

Influence of Preoperative Difference in Lumbar Lordosis Between the Standing and Supine Positions on Clinical Outcomes After Single-Level Transforaminal Lumbar Interbody Fusion: Minimum 2-Year Follow-Up.

Spine (Phila Pa 1976) 2021 Jan 22. Epub 2021 Jan 22.

Department of Orthopaedic Surgery, Eastern Chiba Medical Center, Togane, Chiba, Japan Department of General Medical Science, Graduate School of Medicine, Chiba University, Chiba-city, Chiba, Japan Department of Orthopaedic Surgery, Sawara Prefectural Hospital, Katori, Chiba, Japan Department of Orthopaedic Surgery, University of Tsukuba, Tsukuba, Ibaraki, Japan Department of Orthopaedic Surgery, Toho University Sakura Medical Center, Sakura, Chiba, Japan Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba-city, Chiba, Japan.

Study Design: Retrospective cohort study.

Objective: To investigate whether a preoperative difference in lumbar lordosis (D-LL) between the standing and supine positions is associated with clinical outcomes after transforaminal lumbar interbody fusion (TLIF).

Summary Of Background Data: Several factors have been reported to be associated with surgical outcomes after TLIF. However, the association between preoperative D-LL and clinical outcomes after TLIF is unknown.

Methods: We enrolled 45 lumbar degenerative disease patients (mean age: 65.7 ± 11.3 years old; 24 male) treated with single-level TLIF. Surgical outcomes were assessed using Oswestry disability index, visual analog scale (VAS; low back pain (LBP), lower-extremity pain, numbness, LBP in motion, in standing, and in sitting), Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, Japanese Orthopaedic Association score for intermittent claudication (JOA score), and Nakai's scoring system. The preoperative D-LL between the standing radiograph and computed tomography (CT) in the supine position was defined as LL in supine CT-standing radiograph. Patients were divided into two groups according to D-LL value (D-LL > -4°, and D-LL ≤ -4°). Clinical outcomes were compared between the groups, and correlations between preoperative D-LL and clinical outcomes were analyzed.

Results: There were no significant differences in preoperative clinical parameters between the two groups. Postoperative VASs for lower extremity pain, numbness, LBP in standing, and JOA score in D-LL > -4° group were significantly worse than in the D-LL ≤ -4° group (P < 0.05). Preoperative D-LL showed a weak correlation with postoperative lower extremity pain and numbness (P < 0.05).

Conclusions: This study revealed that lumbar degenerative disease patients, who have greater preoperative kyphotic lumbar alignment in the standing versus supine position, tend to have postoperative residual symptoms after TLIF. A preoperative comparison of lateral radiographs between the standing and supine positions is useful to predict patients' postoperative residual symptoms.Level of Evidence: 3.
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http://dx.doi.org/10.1097/BRS.0000000000003955DOI Listing
January 2021

In vivo kinematics of cruciate-retaining total knee arthroplasty after a change of polyethylene insert configuration.

Asia Pac J Sports Med Arthrosc Rehabil Technol 2021 Apr 31;24:1-8. Epub 2020 Dec 31.

Department of Orthopaedic Surgery, Graduate School of Medical and Pharmaceutical Sciences, Chiba University, Center for Preventive Medical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba City, Chiba, 260-8677, Japan.

Background: To investigate in vivo kinematics of total knee arthroplasty (TKA) with the introduction of a mildly constrained (MC) type of polyethylene (PE). We compared the knee kinematics with a reported pattern after surgery using the same component with a conventionally constrained (CC) type of PE.

Methods: Finite element analysis (FEA) was performed to examine different peak stress distribution of both types of PE. For in vivo study, patients who underwent cruciate-retaining TKA using a total knee system with MC-PE were included. Fluoroscopic surveillance was used to measure the weight-bearing deep knee bend (squatting) using a two-dimensional/three-dimensional (2-D/3-D) registration technique.

Results: FEA analysis revealed the edge loading of the femoral component on PE in CC but not in MC. During the study period, 42 patients underwent TKA with MC-PE. Among them, 13 agreed to participate in the present study. In vivo kinematics analysis found that starting from an average external rotation of femur being 7.1° at 0° of flexion, the rotation slightly decreased to 6.8° at 10° of flexion, then increased with increasing knee flexion until it reached 10.8° at 80° of flexion, and finally decreased to 9.8° at 100° of knee flexion. The results indicate a modest medial pivot pattern. Although the overall pattern was similar for both MC-PE and CC-PE, a slight difference was observed. MC-PE showed a slight internal rotation of 0.3° from 0 to 10° of knee flexion, whereas CC-PE showed a gradual increase of external rotation in this range.

Conclusions: Change of configuration from CC to MC did not substantially affect in vivo kinematics of knees after TKA. Considering the theoretical wider range of allowance of rotation, MC-PE is easier for knee surgeons to use.
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http://dx.doi.org/10.1016/j.asmart.2020.11.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7782324PMC
April 2021

Age-Specific Characteristics of Lumbopelvic Alignment in Patients with Spondylolysis: How Bilateral L5 Spondylolysis Influences Lumbopelvic Alignment During the Aging Process.

World Neurosurg 2021 Mar 29;147:e524-e532. Epub 2020 Dec 29.

Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba-city, Japan.

Background: To elucidate the influence of spondylolysis on age-related lumbar degenerative changes, age-specific lumbopelvic alignment in patients with or without spondylolysis was examined.

Methods: Sagittal reconstructed computed tomography images of the lumbar spine in consecutive patients (n = 581) undergoing computed tomography scans of abdominal or lumbar regions for reasons other than low back disorders were obtained. Lumbar lordosis (LL), L5-S1 angle, and sacral slope (SS) were measured. Lumbopelvic parameters in patients with or without spondylolysis were evaluated in 3 age groups (<50, 50-69, and ≥70). The influence of bilateral L5 spondylolysis (L5-lysis) and L5 vertebral slip on each lumbopelvic parameter, as well as correlation between cross-sectional area (CSA) of paraspinal muscles and the degree of vertebral slip, were examined by multiple regression analysis.

Results: Patients with bilateral spondylolysis showed greater LL and SS than patients without spondylolysis. When analyzing the influence of L5-lysis, only elderly patients (≥70) with L5-lysis showed significantly greater LL and SS than nonspondylolysis (nonlysis) patients. L5-lysis patients more frequently showed L5 vertebral slip than nonlysis patients, and a smaller L5-S1 angle was observed when L5 vertebral slip accompanied L5-lysis. The degree of vertebral slip was significantly correlated with CSA of psoas muscles, but not with CSA of paraspinal extensor muscles.

Conclusions: When patients have L5-lysis, lumbar lordosis and pelvic anteversion occurred age dependently. In elderly patients with L5-lysis, L5 vertebral slip with decrease of the L5-S1 angle occurs frequently. The progression of vertebral slip was correlated with atrophy of psoas muscles, but not that of paraspinal extensor muscles.
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http://dx.doi.org/10.1016/j.wneu.2020.12.097DOI Listing
March 2021

Effects of repeated intra-articular hyaluronic acid on cartilage degeneration evaluated by T1ρ mapping in knee osteoarthritis.

Mod Rheumatol 2020 Oct 16:1-7. Epub 2020 Oct 16.

Minami-Shinjuku Orthopaedic Rehabilitation Clinic, Tokyo, Japan.

Objectives: Intra-articular injection of hyaluronic acid (IAHA) has been used for the treatment of knee osteoarthritis (OA), but its effectiveness remains controversial. This study analyzed knee OA over time by magnetic resonance imaging (MRI) T1ρ mapping to objectively evaluate whether long-term repeated administration of IAHA influences cartilage degeneration.

Methods: Sixty knees of 60 patients [58.3 ± 12.5 years (mean ± standard deviation)] who had multiple T1ρ mapping images were retrospectively analyzed. We calculated the T1ρ values of the medial femorotibial cartilage and classified changes in degenerative areas over time into 3 groups: Improvement, No Change, and Deterioration.

Results: Average time between 2 MRI scans was 7.6 ± 1.2 months. The number of IAHA administrations was 15.5 ± 21.3, 8.39 ± 7.19, and 5.80 ± 7.49 in the Improvement, No Change, and Deterioration groups, respectively. Body mass index and number of IAHA administrations were significant factors causing change in the area of degeneration ( < .05) independent of age, sex, Kellgren-Lawrence grade, and posterior horn meniscus tears.

Conclusion: Cartilage degeneration may be improved with a higher number of administrations of IAHA, based on T1ρ mapping results. This highlights the possibility of increased treatment effectiveness of IAHA for knee OA with repeated administrations.
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http://dx.doi.org/10.1080/14397595.2020.1830483DOI Listing
October 2020

Myovascular Preserving Open-Door Laminoplasty for Cervical Spondylotic Myelopathy With Miniplate Fixation.

Int J Spine Surg 2020 Aug 31;14(4):476-482. Epub 2020 Jul 31.

Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.

Objective: Laminoplasty is an effective procedure for treating cervical spondylotic myelopathy. We conduct myovascular preserving open-door laminoplasty (MPLP) in combination with a laminoplasty plate to improve the stability of the enlarged lamina. We compare the details of the MPLP technique with conventional open-door laminoplasty.

Methods: We compared 25 cases of MPLP (mean age = 70.5, mean follow-up period = 19 months) with 15 controls who received conventional open-door laminoplasty using hydroxyapatite spacers (mean age = 74, mean follow-up period = 53 months). Regarding surgical outcomes, blood loss, operative time, Japanese Orthopaedic Association score, and postoperative visual analog score for neck pain were measured. Regarding image analysis, preoperative and postoperative range of motion (ROM), C2-7 angle, implant back out, hinge bone fusion time, presence or absence of hinge bone union failure, and posterior neck fat infiltration rate were evaluated.

Results: Operative time was significantly shorter for MPLP, and postoperative neck pain was significantly decreased. In image evaluation, %ROM was significantly increased in MPLP, but no difference in C2-7 angle existed between the 2 groups. Implant back out was not recognized in either group. In MPLP, the hinge union period was significantly shortened, and the postoperative fat infiltration rate was significantly decreased.

Conclusions: We were able to reduce neck pain after surgery by an approach entailing longitudinal splitting of the spinous processes. We were able to ensure shorter operation times due to cervical plates and better hinge bone fusion times due to initial stability.

Level Of Evidence: 4.
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http://dx.doi.org/10.14444/7062DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7478064PMC
August 2020

Does the increased motion probing gradient directional diffusion tensor imaging of lumbar nerves using multi-band SENSE improve the visualization and accuracy of FA values?

Eur Spine J 2020 07 4;29(7):1693-1701. Epub 2020 May 4.

Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba, 260-8670, Japan.

Purpose: Diffusion tensor imaging (DTI) is useful to evaluate lumbar nerves visually and quantitatively. Multi-band sensitivity encoding (MB-SENSE) is a technique to reduce the scan time. This study aimed to investigate if super-multi-gradient DTI with multi-band sensitivity encoding (MB-SENSE) is better in evaluating lumbar nerves than the conventional method.

Methods: The participants were 12 healthy volunteers (mean age 33.6 years). In all subjects, DTI was performed using echo planar imaging with different motion probing gradient (MPG) directions (15 without MB, and 15, 32, 64, and 128 with MB) and the lumbar nerve roots were visualized with tractography. In the five groups, we evaluated the resultant DTI both visually and quantitatively. For visual measures, we counted the number of fluffs and disruptions of the nerve fibers. For quantitative measures, the fractional anisotropy (FA) and standard deviation of the fractional anisotropy (FA-SD) values at two regions (proximal and distal) of the lumbar nerve roots were quantified and compared.

Results: Among the five groups, the number of fluffs decreased as the number of MPG directions increased. However, the number of disruptions showed no significant differences. The FA-SD values decreased as the number of MPG directions increased, indicating that the signal variation was reduced with multi-gradient directional DTI.

Conclusion: High-resolution multi-directional DTI with MB-SENSE may be useful to visualize nerve entrapments and may allow for more accurate DTI parameter quantification with opportunities for clinical diagnostic applications.
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http://dx.doi.org/10.1007/s00586-020-06430-7DOI Listing
July 2020

Diagnosis of lumbar radiculopathy using simultaneous MR neurography and apparent T2 mapping.

J Clin Neurosci 2020 Aug 24;78:339-346. Epub 2020 Apr 24.

Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, 1-8-1 Inohana, Chuo-ku 260-0856, Japan. Electronic address:

We sought to assess the utility of simultaneous apparent T2 mapping and neurography with the nerve-sheath signal increased by inked rest-tissue rapid acquisition of relaxation-enhancement imaging (SHINKEI-Quant) for the quantitative evaluation of compressed nerves in patients with lumbar radiculopathy. Thirty-two patients with lumbar radiculopathy and 5 healthy subjects underwent simultaneous apparent T2 mapping and neurography with SHINKEI-Quant. Regions of interest (ROIs) were placed in the lumbar dorsal root ganglia (DRG) and the spinal nerves distal to the lumbar nerves bilaterally at L4-S1. The T2 relaxation times were measured on the affected and unaffected sides. The T2 ratio was calculated as the affected side/unaffected side. Pearson correlation coefficients were calculated to determine the correlation between the T2 relaxation times or T2 ratio and clinical symptoms. An ROC curve was used to examine the diagnostic accuracy and threshold of the T2 relaxation times and T2 ratio. We observed no significant differences in the T2 relaxation times between the nerve roots on the left and right at each spinal level in healthy subjects. In patients, lumbar neurography revealed swelling of the involved nerve, and prolonged T2 relaxation times compared with that of the contralateral nerve. The T2 ratio correlated with leg pain. The ROC analysis revealed that the T2 relaxation time threshold was 127 ms and the T2 ratio threshold was 1.07. To our knowledge, this is the first study to show the utility of SHINKEI-Quant for the quantitative evaluation of lumbar radiculopathy.
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http://dx.doi.org/10.1016/j.jocn.2020.04.072DOI Listing
August 2020

Prevalence of lumbar spondylolysis and spondylolisthesis in patients with degenerative spinal disease.

Sci Rep 2020 04 21;10(1):6739. Epub 2020 Apr 21.

Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.

Lumbar spondylolysis generally occurs in adolescent athletes. Bony union can be expected with conservative treatment, however, the fracture does not heal in some cases. When the fracture becomes a pseudoarthrosis, spondylolysis patients have the potential to develop isthmic spondylolisthesis. A cross-sectional study was performed to determine the incidence of spondylolysis and spondylolisthesis, and to elucidate when and how often spondylolisthesis occurs in patients with or without spondylolysis. Patients undergoing computed tomography (CT) scans of abdominal or lumbar regions for reasons other than low back pain were included (n = 580). Reconstruction CT images were obtained, and the prevalence of spondylolysis and spondylolisthesis were evaluated. Of the 580 patients, 37 patients (6.4%) had spondylolysis. Of these 37 patients, 19 patients (51.4%) showed spondylolisthesis, whereas only 7.4% of non-spondylolysis patients showed spondylolisthesis (p < 0.05). When excluding unilateral spondylolysis, 90% (18/20) of spondylolysis patients aged ≥60 years-old showed spondylolisthesis. None of the patients with isthmic spondylolisthesis had received fusion surgery, suggesting that most of these patients didn't have a severe disability requiring surgical treatment. Our results showed that the majority of bilateral spondylolysis patients aged ≥60 years-old show spondylolisthesis, and suggest that spondylolisthesis occurs very frequently and may develop at a younger age when spondylolysis exists.
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http://dx.doi.org/10.1038/s41598-020-63784-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7174286PMC
April 2020

Microstructural heterogeneity in the electrodeposited Ni: insights from growth modes.

Sci Rep 2020 Mar 26;10(1):5548. Epub 2020 Mar 26.

Department of Materials Design Innovation Engine, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan.

Microstructures of electrodeposited Ni were studied from the perspective of growth modes during electrodeposition. The electrodeposited Ni had a heterogeneous microstructure composed of nanocrystalline- and microcrystalline-grains. Electron backscatter diffraction analyses showed that nanocrystalline- and microcrystalline-grains were preferentially oriented to specific planes. Secondary ion mass spectrometry also revealed that coarse-grained regions had higher S content than that of finer-grained regions. Hence, microstructural heterogeneity in electrodeposited Ni is reflected by the overlap of inhibited and free growth modes. Our discussion surrounding microstructural heterogeneity also provides insight into other electrodeposited nanocrystalline systems.
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http://dx.doi.org/10.1038/s41598-020-62565-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7098977PMC
March 2020

Evaluating Spinal Canal Lesions Using Apparent Diffusion Coefficient Maps with Diffusion-Weighted Imaging.

Asian Spine J 2020 Jun 14;14(3):312-319. Epub 2020 Feb 14.

Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.

Study Design: Observational study.

Purpose: To evaluate healthy volunteers and patients with spinal canal lesions using apparent diffusion coefficient (ADC) maps with diffusion-weighted imaging.

Overview Of Literature: Decompression surgery for lumbar spinal stenosis (LSS) is selected on the basis of subjective assessment and cross-sectional magnetic resonance imaging (MRI). However, there is no objective standard for this procedure.

Methods: We performed 3T MRI in 10 healthy volunteers and 13 patients with LSS. The ADC values in the spinal canal were evaluated at 46 vertebrae (L4/5 and L5/S1 for each participant), and the reduced and conventional fields of view were compared.

Results: The ADC values were 2.72±0.12 at L4/5 in healthy volunteers, 2.76±0.19 at L5/S1 in healthy volunteers, 1.77±0.58 at L4/5 in patients with LSS, and 2.35±0.29 at L5/S1 in patients with LSS. The ADC value at L4/5 in patients with LSS was significantly lower than that at L5/S1 in patients with LSS and that at L4/5 and L5/S1 in healthy volunteers (p <0.05). With an ADC cutoff value of 2.46 to identify LSS, this approach provided an area under the curve of 0.81, sensitivity of 0.92, and specificity of 0.76 (p <0.05).

Conclusions: Preoperative examination using ADC maps permits visualization and quantification of spinal canal lesions, thus proving the utility of ADC maps in the selection of decompression surgery for LSS.
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http://dx.doi.org/10.31616/asj.2019.0266DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7280930PMC
June 2020

Simultaneous MR neurography and apparent T2 mapping of cervical nerve roots before microendoscopic surgery to treat patient with radiculopathy due to cervical disc herniation: Preliminary results.

J Clin Neurosci 2020 Apr 13;74:213-219. Epub 2019 Sep 13.

Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, 1-8-1 Inohana, Chuo-ku, 260-0856, Japan. Electronic address:

There is no imaging modality to quantitatively evaluate compressed cervical nerve roots in cervical radiculopathy. Here we sought to evaluate the usefulness of simultaneous apparent T2 mapping and neurography with nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation-enhancement imaging (SHINKEI-Quant) to evaluate compressed nerves quantitatively in patients with cervical radiculopathy due to cervical disc hernia before microendoscopic surgery. One patient with cervical radiculopathy due to cervical disc hernia before microendoscopic surgery and 5 healthy subjects underwent simultaneous apparent T2 mapping and neurography with SHINKEI-Quant. The patient was a 49-year-old man with severe right upper arm pain and numbness. Based on MRI images, we suspected right C7 radiculopathy due to C6-7 cervical disc hernia. The T2 relaxation times of the cervical dorsal root ganglia of the brachial plexus bilaterally at C5-C8 were measured. We observed no significant differences in T2 relaxation times between the nerve roots on the left and right at each spinal level with values in healthy subjects. In our patient, neurography revealed swelling of the right C7 nerve, and a prolonged T2 relaxation time compared with that of the contralateral, unaffected C7 nerve. We performed microendoscopic surgery and the symptoms improved. We were able to evaluate the injured nerve root quantitatively in a patient with cervical radiculopathy using the SHINKEI-Quant technique, being the first study to our knowledge to show the usefulness of this technique to evaluate cervical radiculopathy quantitatively before microendoscopic surgery.
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http://dx.doi.org/10.1016/j.jocn.2019.08.099DOI Listing
April 2020

Efficacy of HYADD®4-G single intra-discal injections in a rabbit model of intervertebral disc degeneration.

Biomed Mater Eng 2019 ;30(4):403-417

Fidia Farmaceutici SpA, Abano Terme, Italy.

Background: Various biomaterials/technologies have been tested for treatment of intervertebral disc (IVD) degeneration (IDD). Only few non-surgical options exist.

Objective: Assessment of efficacy and safety of the hyaluronic acid derivative hydrogel HYADD®4-G in IDD using a well-established rabbit annular puncture model.

Methods: Rabbits were punctured at two IVDs to induce IDD. Thirty days after, IVDs were injected with HYADD®4-G or saline. IVD hydration, height, appearance and tissue organization were assessed by radiographs, MRI and histopathology. Safety of HYADD®4-G injection was evaluated in non-punctured IVDs.

Results: HYADD®4-G injection restored disc height to over 75% of the pre-punctured disc, saline injections led to 50% of initial disc height. Compared to saline, HYADD®4-G treatment resulted in improved water retention as revealed by MRI quantification. 83.3% of HYADD®4-G injected discs had normal appearance and reached grade I of the Pfirrmann scale. Regarding tissue organization and cellularity, HYADD®4-G treatment resulted in significantly lower IDD scores than saline (p < 0.01). HYADD®4-G injected into healthy IVDs did not induce inflammation or foreign body reactions.

Conclusions: Intra-discal HYADD®4-G injection is safe and has therapeutic benefits: IDD could be limited through restoration of disc height and hydration and maintenance of normal IVD tissue organization.
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http://dx.doi.org/10.3233/BME-191062DOI Listing
February 2020

Relationship between postoperative retear and preoperative fatty degeneration in large and massive rotator cuff tears: quantitative analysis using T2 mapping.

J Shoulder Elbow Surg 2019 Aug;28(8):1562-1567

Department of Orthopaedic Surgery, Eastern Chiba Medical Center, Togane, Chiba, Japan.

Background: Fatty degeneration of the rotator cuff muscles is reported to be associated with retear after rotator cuff repair. The purpose of this study was to assess the relationship between retear and preoperative fatty degeneration, as quantified by T2 mapping.

Methods: This prospective cohort study included 83 large and 24 massive rotator cuff tears (average age, 67 years; range, 46-82 years). All patients preoperatively underwent T2 mapping magnetic resonance imaging, and T2 values of the supraspinatus and infraspinatus muscles were quantified. Cuff integrity was evaluated with magnetic resonance imaging 1 year postoperatively. Preoperative T2 values were compared between the retear and intact groups. The preoperative Goutallier stage, Constant score, and the shoulder score of the University of California at Los Angeles were also compared between the 2 groups.

Results: Retear was found in 32 shoulders (30%). Postoperative Constant and University of California at Los Angeles scores were significantly higher in intact shoulders than in retear shoulders (P < .001 for both). Mean preoperative T2 values of supraspinatus and infraspinatus were 77.4 ± 13.2 ms and 73.2 ± 15.3 ms in retear shoulders and 66.5 ± 11.1 ms and 58.6 ± 11.7 ms in intact shoulders, respectively; the differences were significant in both muscles (P < .001). Cutoff values for prediction of retear were 71.8 ms in supraspinatus and 63.1 ms in infraspinatus. There were no significant differences in the preoperative Goutallier stages of supraspinatus and infraspinatus between the 2 groups.

Conclusions: Retear shoulders demonstrated significantly higher preoperative T2 values than intact shoulders. T2 mapping can be a useful tool for predicting postoperative retears.
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http://dx.doi.org/10.1016/j.jse.2019.04.036DOI Listing
August 2019

Functional Assessment of Lumbar Nerve Roots Using Coronal-plane Single-shot Turbo Spin-echo Diffusion Tensor Imaging.

Magn Reson Med Sci 2020 May 13;19(2):159-165. Epub 2019 Jun 13.

Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University.

We investigated the usefulness of diffusion tensor imaging using single-shot turbo spin-echo sequence (TSE-DTI) in detecting the responsible nerve root by multipoint measurements of fractional anisotropy (FA) values. Five patients with bilateral lumbar spinal stenosis showing unilateral neurological symptoms were examined using TSE-DTI. In the spinal canal, FA values in the symptomatic side were lower than those in the asymptomatic side. TSE-DTI using multipoint measurements of FA values can differentiate the responsible lumbar nerve root.
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http://dx.doi.org/10.2463/mrms.tn.2019-0014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7232038PMC
May 2020

Diffusion tensor tractography of the lumbar nerves before a direct lateral transpsoas approach to treat degenerative lumbar scoliosis.

J Neurosurg Spine 2019 Jan 25:1-9. Epub 2019 Jan 25.

2Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba.

OBJECTIVEThe purpose of this study was to determine the relationship between vertebral bodies, psoas major morphology, and the course of lumbar nerve tracts using diffusion tensor imaging (DTI) before lateral interbody fusion (LIF) to treat spinal deformities.METHODSDTI findings in a group of 12 patients (all women, mean age 74.3 years) with degenerative lumbar scoliosis (DLS) were compared with those obtained in a matched control group of 10 patients (all women, mean age 69.8 years) with low-back pain but without scoliosis. A T2-weighted sagittal view was fused to tractography from L3 to L5 and separated into 6 zones (zone A, zones 1-4, and zone P) comprising equal quarters of the anteroposterior diameters, and anterior and posterior to the vertebral body, to determine the distribution of nerves at various intervertebral levels (L3-4, L4-5, and L5-S1). To determine psoas morphology, the authors examined images for a rising psoas sign at the level of L4-5, and the ratio of the anteroposterior diameter (AP) to the lateral diameter (lat), or AP/lat ratio, was calculated. They assessed the relationship between apical vertebrae, psoas major morphology, and the course of nerve tracts.RESULTSAlthough only 30% of patients in the control group showed a rising psoas sign, it was present in 100% of those in the DLS group. The psoas major was significantly extended on the concave side (AP/lat ratio: 2.1 concave side, 1.2 convex side). In 75% of patients in the DLS group, the apex of the curve was at L2 or higher (upper apex) and the psoas major was extended on the concave side. In the remaining 25%, the apex was at L3 or lower (lower apex) and the psoas major was extended on the convex side. Significant anterior shifts of lumbar nerves compared with controls were noted at each intervertebral level in patients with DLS. Nerves on the extended side of the psoas major were significantly shifted anteriorly. Nerve pathways on the convex side of the scoliotic curve were shifted posteriorly.CONCLUSIONSA significant anterior shift of lumbar nerves was noted at all intervertebral levels in patients with DLS in comparison with findings in controls. On the convex side, the nerves showed a posterior shift. In LIF, a convex approach is relatively safer than an approach from the concave side. Lumbar nerve course tracking with DTI is useful for assessing patients with DLS before LIF.
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http://dx.doi.org/10.3171/2018.9.SPINE18834DOI Listing
January 2019

Volume change in infrapatellar fat pad is associated not with obesity but with cartilage degeneration.

J Orthop Res 2019 03 3;37(3):593-600. Epub 2019 Jan 3.

Department of Orthopaedic Surgery, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113-8603, Japan.

Infrapatellar fat pad has been implicated in knee osteoarthritis. We examined whether infrapatellar fat pad volume is associated with quantitative cartilage changes using magnetic resonance imaging T1ρ mapping. Fifty-eight knees of knee pain patients (19 men, 39 women, mean age 57.0 [range 29-85] years) who were conservatively managed and had >1 T1ρ mapping images taken over time were evaluated. We used three slices from the medial femoral and tibial cartilage; areas showing T1ρ values <130 ms and >50 ms were designated as having cartilage degeneration. Cases were categorized into three groups: Improvement, No Change, and Deterioration. Fat-suppressed T2-weighted sagittal magnetic resonance images were used for measuring infrapatellar fat pad volume. Percent change in infrapatellar fat pad volume was -5.01 ± 5.66%, -2.06 ± 4.92%, and 0.05 ± 6.09% in the Improvement (n = 22), No Change (n = 22), and Deterioration (n = 14) groups, respectively, demonstrating significantly reduced infrapatellar fat pad volume in the Improvement group (p < 0.05). Multivariate regression analyses revealed that the percent change in infrapatellar fat pad volume significantly affected T1ρ change category independent of age, sex, follow-up period, baseline infrapatellar fat pad volume, and Kellgren-Lawrence grade. Infrapatellar fat pad volume and obesity or body weight change showed no correlation. Infrapatellar fat pad volume was reduced in patients with improved quantitative cartilage assessment on magnetic resonance imaging T1ρ mapping. This is the first study demonstrating associations between quantitative cartilage changes and infrapatellar fat pad morphological changes, suggesting a detrimental role of infrapatellar fat pad volume in articular cartilage degeneration. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.
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http://dx.doi.org/10.1002/jor.24201DOI Listing
March 2019

Superior graft maturation after anatomical double-bundle anterior cruciate ligament reconstruction using the transtibial drilling technique compared to the transportal technique.

Knee Surg Sports Traumatol Arthrosc 2019 Aug 29;27(8):2468-2477. Epub 2018 Oct 29.

Department of Radiology, Toho University Sakura Medical Center (Chiba), Chiba, Japan.

Purpose: To evaluate and compare the femoral tunnel aperture position, graft bending angle and the magnetic resonance imaging (MRI) graft signal intensity after anatomical double-bundle anterior cruciate ligament (ACL) reconstruction between transtibial and transportal drilling techniques of the femoral tunnel.

Methods: Eighty-seven patients who underwent anatomic double-bundle ACL reconstruction with hamstring tendon autograft between January 2012 and December 2014 were included in this retrospective study. Forty-one patients underwent reconstruction using a transportal technique (TP group) and 46 patients underwent reconstruction using a transtibial technique (TT group). The anteromedial (AM) femoral aperture position and the graft bending angle were assessed using transparent three-dimensional CT 2 weeks postoperatively. MRI assessment was performed with proton density-weighted images in an oblique coronal plane 6 and 12 months postoperatively. Signal/noise quotient was calculated for two specific graft sites (femoral tunnel site and mid-substance site). Femoral aperture position, the graft bending angle and signal/noise quotient were compared between the TP and TT groups.

Results: There was no significant difference in the aperture position between the two groups. The graft bending angle of the AM tunnel in the axial plane was significantly greater in the TP group (p < 0.001). On the other hand, the TP group had a significantly more acute angle in the coronal plane (p < 0.001). There was no significant difference at either site in the signal/noise quotient of the graft between the two groups at 6 months. However, the TT group had a lower signal/noise quotient at 12 months at both sites (femoral aperture: p = 0.04, mid-substance: p = 0.004).

Conclusion: There was a significant difference in signal/noise quotient between the two drilling techniques 12 months postoperatively. There was no significant difference in femoral tunnel aperture position between the two groups. However, graft bending angle at the femoral tunnel aperture was significantly different between the two groups, indicating the possibility that graft bending angle is a factor that influences graft maturation. This indicates that the TT technique has an advantage over the TP technique in terms of graft maturation.
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http://dx.doi.org/10.1007/s00167-018-5240-8DOI Listing
August 2019

Muscle type-specific RNA polymerase II recruitment during PGC-1α gene transcription after acute exercise in adult rats.

J Appl Physiol (1985) 2018 Aug 16. Epub 2018 Aug 16.

Graduate School of Health Sciences, Matsumoto University, Japan.

Epigenetic regulation of gene expression differs between fast- and slow-twitch skeletal muscles in adult rats, although the precise mechanisms are still unknown. The present study investigates the differences in responses of RNA polymerase II (Pol II) and histone acetylation during transcriptional activation in the plantaris and soleus muscles of adult rats after acute treadmill running. We targeted the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) gene to analyze epigenomic changes by chromatin immunoprecipitation. The mRNA expression of the PGC-1α-b isoform was significantly up-regulated in both plantaris and soleus muscles 2 h after acute running, although the magnitude of the up-regulation was more pronounced in the plantaris muscle. The sequences of proximal exons of the PGC-1α locus were expressed more in the plantaris muscle after acute running. Accumulation of Pol II was noted near the alternative exon 1 in both plantaris and soleus muscles in association with the enhanced distribution of acetylated histone 3. Accumulation of Pol II was also observed at the transcription start site, exon 2, and exon 3 in the plantaris muscle, but not the soleus muscle. It was noted that in the soleus muscle, acetylation of histone 3 at lysine 27 was enhanced throughout the PGC-1α locus in response to transcriptional activation, suggesting that elongating Pol II was capable of traveling through to the end of the locus. These results indicate that the mobility of Pol II during PGC-1αtranscription differed between fast- and slow-twitch skeletal muscles, affecting the strength of the transcriptional activity.
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http://dx.doi.org/10.1152/japplphysiol.00202.2018DOI Listing
August 2018

Evaluation of Lumbar Intervertebral Disc Degeneration Using T1ρ and T2 Magnetic Resonance Imaging in a Rabbit Disc Injury Model.

Asian Spine J 2018 Apr 16;12(2):317-324. Epub 2018 Apr 16.

Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.

Study Design: An histologic and magnetic resonance imaging (MRI) study of lumbar intervertebral disc (IVD) degeneration was conducted.

Purpose: To clarify the sensitivity and efficacy of T1ρ/T2 mapping for IVD degeneration, the correlation between T1ρ/T2 mapping and degenerative grades and histological findings in the lumbar IVD were investigated.

Overview Of Literature: The early signs of IVD degeneration are proteoglycan loss, dehydration, and collagen degradation. Recently, several quantitative MRI techniques have been developed; T2 mapping can be used to evaluate hydration and collagen fiber integrity within cartilaginous tissue, and T1ρ mapping can be used to evaluate hydration and proteoglycan content.

Methods: Using New Zealand White rabbits, annular punctures of the IVD were made 10 times at L2/3, 5 times at L3/4, and one time at L4/5 using an 18-gauge needle (n=6) or a 21-gauge needle (n=6). At 4 and 8 weeks post-surgery, MRI was performed including T1ρ and T2 mapping. The degree of IVD degeneration was macroscopically assessed using the Thompson grading system. All specimens were cut for hematoxylin and eosin, safranin-O, and toluidine blue staining.

Results: Disc degeneration became more severe as the number of punctures increased and when the larger needle was used. T1ρ and T2 values were significantly different between grade 1 and grade 3 IVDs, grade 1 and grade 4 IVDs, grade 2 and grade 3 IVDs, and grade 2 and grade 4 IVDs (<0.05). There was a significant difference between grade 1 and grade 2 IVDs only in terms of T1ρ values (<0.05).

Conclusions: T1ρ and T2 quantitative MRI could detect these small differences. Our results suggest that T1ρ and T2 mapping are sensitive to degenerative changes of lumbar IVDs and that T1ρ mapping can be used as a clinical tool to identify early IVD degeneration.
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http://dx.doi.org/10.4184/asj.2018.12.2.317DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913024PMC
April 2018

Distortion-free diffusion tensor imaging for evaluation of lumbar nerve roots: Utility of direct coronal single-shot turbo spin-echo diffusion sequence.

Magn Reson Imaging 2018 06 31;49:78-85. Epub 2018 Jan 31.

Department of Radiology, Eastern Chiba Medical Center, 3-6-2 Okayamadai, Togane, Chiba 2838686, Japan.

Purpose: Diffusion tensor imaging (DTI) based on a single-shot echo planer imaging (EPI-DTI) is an established method that has been used for evaluation of lumbar nerve disorders in previous studies, but EPI-DTI has problems such as a long acquisition time, due to a lot of axial slices, and geometric distortion. To solve these problems, we attempted to apply DTI based on a single-shot turbo spin echo (TSE-DTI) with direct coronal acquisition. Our purpose in this study was to investigate whether TSE-DTI may be more useful for evaluation of lumbar nerve disorders than EPI-DTI.

Materials And Methods: First, lumbar nerve roots of five healthy volunteers were evaluated for optimization of imaging parameters with TSE-DTI including b-values and the number of motion proving gradient (MPG) directions. Subsequently, optimized TSE-DTI was quantitatively compared with conventional EPI-DTI by using fractional anisotropy (FA) values and visual scores in subjective visual evaluation of tractography. Lumbar nerve roots of six patients, who had unilateral neurologic symptoms in one leg, were evaluated by the optimized TSE-DTI.

Results: TSE-DTI with b-value of 400 s/mm and 32 diffusion-directions could reduce the image distortion compared with EPI-DTI, and showed that the average FA values on the symptomatic side for six patients were significantly lower than those on the non-symptomatic side (P < 0.05).

Conclusion: Tractography with TSE-DTI might show damaged areas of lumbar nerve roots without severe image distortion. TSE-DTI might improve the reproducibility in measurements of FA values for quantification of a nerve disorder, and would become a useful tool for diagnosis of low back pain.
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http://dx.doi.org/10.1016/j.mri.2018.01.003DOI Listing
June 2018

Recent advances in magnetic resonance neuroimaging of lumbar nerve to clinical applications: A review of clinical studies utilizing Diffusion Tensor Imaging and Diffusion-weighted magnetic resonance neurography.

Spine Surg Relat Res 2017 20;1(2):61-71. Epub 2017 Dec 20.

Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Japan.

Much progress has been made in neuroimaging with Magnetic Resonance neurography and Diffusion Tensor Imaging (DTI) owing to higher magnetic fields and improvements in pulse sequence technology. Reports on lumbar nerve DTI have also increased considerably. Many studies have shown that the use of DTI in lumbar nerve lesions, such as lumbar foraminal stenosis and lumbar disc herniation, makes it possible to capture images of interruptions of tractography at stenotic sties, enabling the diagnosis of stenosis. DTI can also reveal significant decreases in fractional anisotropy (FA) with significant increases in apparent diffusion coefficient (ADC) values in compression lesions. FA values have higher accuracy than ADC values. Furthermore, strong correlations exist between FA values and indications of neurological severity, including the Japanese Orthopedic Association (JOA) score, the Oswestry Disability Index (ODI), and the Roland-Morris Disability Questionnaire (RDQ) in patients with lumbar disc herniation-induced radiculopathy. Most lumbar DTI has become 3T; 3T MRI has made it possible to take high-resolution DTI measurements in a short period of time. However, increased motion artifacts in the magnetic susceptibility effect lead to signal irregularities and image distortion. In the future, high-resolution DTI with reduced field-of-view may become useful in clinical applications, since visualization of nerve lesions and quantification of DTI parameters could allow more accurate diagnoses of lumbar nerve dysfunctions. Future translational studies will be necessary to successfully bring MR neuroimaging of lumbar nerve into clinical use.
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http://dx.doi.org/10.22603/ssrr.1.2016-0015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6698557PMC
December 2017

Visualization of lumbar nerves using reduced field of view diffusion tensor imaging in healthy volunteers and patients with degenerative lumbar disorders.

Br J Radiol 2017 Dec 13;90(1080):20160929. Epub 2017 Sep 13.

1 Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Inohana, Chuo-ku , Graduate School of Medicine, Chiba University, Inohana, Chuo-ku , Chiba , Japan.

Objective: We investigated high resolution diffusion tensor imaging (DTI) of lumbar nerves with reduced field of view (rFOV) using 3 T MRI.

Methods: DTI measured with rFOV was compared with conventional FOV (cFOV) 3.0 T MRI in 5 healthy volunteers and 10 patients with degenerative lumbar disorders. The intracanal, foramina and extraforamina of the L5 nerve were established as the regions of interest and fractional anisotropy (FA) values and apparent diffusion coefficient (ADC) values were measured. Image quality for tractography and FA maps and ADC maps, interindividual and intraindividual reliability of FA and ADC, and signal-to-noise (SNR) were studied.

Results: Both of image qualities with tractography, FA map and ADC map showed that lumbar nerves were more clearly imaged with the rFOV. Intraindividual reliability was higher with rFOV compared with the conventional method for ADC values, while interindividual reliability was higher for both FA values and ADC values with the rFOV method over the conventional method (p < 0.05). Significantly higher SNR was obtained with rFOV compared with cFOV in the spinal canal (p < 0.05).

Conclusion: rFOV enabled clearer imaging of the lumbar nerve, allowing for more accurate measurement of FA and ADC values. Significantly higher SNR was obtained with rFOV compared with cFOV in the spinal canal. To our knowledge, this research showed for the first time the usefulness of rFOV in patients with degenerative lumbar disorders. High resolution DTI using rFOV may become useful in clinical applications because visualization of nerve entrapments and quantification of DTI parameters may allow more accurate diagnoses of lumbar nerve dysfunction. Advances in knowledge: Compared with traditional methods, rFOV allows for clear imaging of the lumbar nerve and enables accurate measurements of the FA and ADC values. High-resolution DTI with rFOV may be used to visualize nerve entrapments and allow for more accurate diagnosis of DTI parameter quantification with opportunities for clinical applications.
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http://dx.doi.org/10.1259/bjr.20160929DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6047648PMC
December 2017

Comparative Analysis of Gene Expression between Cartilage and Menisci in Early-Phase Osteoarthritis of the Knee-An Animal Model Study.

J Knee Surg 2018 Aug 15;31(7):664-669. Epub 2017 Sep 15.

Department of Orthopaedic Surgery, Chiba University, Graduate School of Medicine, Chiba, Japan.

Cartilage degeneration is believed to be the primary event in the development of osteoarthritis (OA). On the other hand, meniscal degeneration is observed with high prevalence, and some researchers have pointed out that pathological changes in menisci precede that of cartilage. The purpose of the present study is to investigate comprehensive gene expression pattern of cartilage and menisci in the initial phase of surgically induced OA and to compare them. Secondary OA was surgically induced in 10-week-old male Wistar rats by anterior cruciate ligament transection (ACLT). Articular cartilage and menisci were separately dissected from six ACLT- and six sham-operated rats. Each specimen was analyzed by microarray, histological, and immunohistochemical analysis 3 weeks after surgery. Of the 36,685 transcripts detectable by microarray, the number of upregulated transcripts in ACLT menisci was >2.5-fold compared with that in ACLT menisci in any given threshold. Cluster analysis using the Database for Annotation Visualization and Integrated Discovery (DAVID) showed genes related to OA, such as response to stimulus, angiogenesis, and apoptosis, which were predominantly found in menisci in ACLT rats. Representative proteases including Adamts2, 4, Mmp2, 12, 13, 14, 16, extracellular matrix genes including versican (Vcan), lumican (Lum), syndecan1 (Sdc1), and Prostaglandin endoperoxide synthase2 (Ptgs2) were up-regulated in menisci, but were not up-regulated in cartilage. Our results indicated that the molecular changes that occurred in menisci preceded those occurred in cartilage in the very early phase of surgically induced OA models.
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http://dx.doi.org/10.1055/s-0037-1606549DOI Listing
August 2018

Bone morphological factors influencing cartilage degeneration in the knee.

Mod Rheumatol 2018 Mar 23;28(2):351-357. Epub 2017 Aug 23.

a Department of Orthopaedic Surgery , Nippon Medical School , Tokyo , Japan.

Objectives: Morphological features of the distal femur and proximal tibia associated with cartilage degeneration are unknown. This study aimed to elucidate local anatomical parameters of the knee which correlate with articular cartilage degeneration using MRI T1ρ mapping.

Methods: This study involved 200 subjects with knee pain (mean age, 48.7 years; range, 14-80 years) with no severe osteoarthritic changes on plain X-ray. T1ρ values were measured in the regions of interest on the surface layer of the cartilage on mid-coronal images of the femorotibial joint. Assessment of medial and lateral posterior tibial slope (MTS, LTS) and medial and lateral femoral condylar offset ratio (MFCOR, LFCOR) was performed using sagittal proton density-weighted imaging. Morphological assessment of posterior root and horn of menisci was also performed according to a modified Whole Organ Magnetic Resonance Imaging Score (WORMS) of the knee.

Results: Multiple regression analysis revealed that a decrease in MTS was associated with increased T1ρ values in the medial tibia, independent of age, osteoarthritic changes on plain X-ray, femur-tibia angle (FTA), and posterior medial meniscal lesions.

Conclusions: Shallow MTS correlates with cartilage degeneration in symptomatic patients. This parameter could help in understanding the etiology of osteoarthritis in the early stage. Future kinematic studies will be needed to confirm our findings.
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http://dx.doi.org/10.1080/14397595.2017.1332539DOI Listing
March 2018

Running training experience attenuates disuse atrophy in fast-twitch skeletal muscles of rats.

J Appl Physiol (1985) 2017 Oct 3;123(4):902-913. Epub 2017 Aug 3.

Department of Sports and Health Science, Faculty of Human Health Science, Matsumoto University, Niimura, Matsumoto City, Nagano, Japan;

Responsiveness to physiological stimuli, such as exercise and muscular inactivation, differs in individuals. However, the mechanisms responsible for these individual differences remain poorly understood. We tested whether a prior experience of exercise training affects the responses of skeletal muscles to unloading. Young rats were assigned to perform daily running training with a treadmill for 8 wk. After an additional 8 wk of normal habitation, the rats were hindlimb unloaded by tail suspension for 1 wk. Fast-twitch plantaris, gastrocnemius, and tibialis anterior muscles did not atrophy after unloading in rats with training experience, although soleus muscle lost weight similar to sedentary rats. We also analyzed the transcriptome in plantaris muscle with RNA sequencing followed by hierarchical clustering analysis and found that a subset of genes that were generally upregulated in sedentary rats after unloading were less responsive in rats with training experience. The distribution of histone 3 was diminished at the loci of these genes during the training period. Although the deposition of histone 3 was restored after an additional period of normal habitation, the incorporation of H3.3 variant was promoted in rats with training experience. This remodeling of nucleosomes closely correlated to the conformational changes of chromatin and suppressed gene expression in response to unloading. These results suggest that exercise training stimulated the early turnover of histone components, which may alter the responsiveness of gene transcription to physiological stimuli. The present study demonstrates that disuse atrophy was suppressed in fast-twitch skeletal muscles of rats with training experience in early life. We also found a subset of genes that were less responsive to unloading in the muscle of rats with training experience. It was further determined that exercise training caused an early turnover of nucleosome components, which may alter the responsiveness of genes to stimulus in later life.
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http://dx.doi.org/10.1152/japplphysiol.00289.2017DOI Listing
October 2017

Anatomical evaluation of lumbar nerves using diffusion tensor imaging and implications of lateral decubitus for lateral transpsoas approach.

Eur Spine J 2017 11 7;26(11):2804-2810. Epub 2017 Apr 7.

Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba, 260-8670, Japan.

Purpose: Recently, lateral interbody fusion (LIF) has become more prevalent, and evaluation of lumbar nerves has taken on new importance. We report on the assessment of anatomical relationships between lumbar nerves and vertebral bodies using diffusion tensor imaging (DTI).

Methods: Fifty patients with degenerative lumbar disease and ten healthy subjects underwent DTI. In patients with lumbar degenerative disease, we studied nerve courses with patients in the supine positions and with hips flexed. In healthy subjects, we evaluated nerve courses in three different positions: supine with hips flexed (the standard position for MRI); supine with hips extended; and the right lateral decubitus position with hips flexed. In conjunction with tractography from L3 to L5 using T2-weighted sagittal imaging, the vertebral body anteroposterior span was divided into four equally wide zones, with six total zones defined, including an anterior and a posterior zone (zone A, zones 1-4, zone P). We used this to characterize nerve courses at disc levels L3/4, L4/5, and L5/S1.

Results: In patients with degenerative lumbar disease, in the supine position with hips flexed, all lumbar nerve roots were located posterior to the vertebral body centers in L3/4 and L4/5. In healthy individuals, the L3/4 nerve courses were displaced forward in hips extended compared with the standard position, whereas in the lateral decubitus position, the L4/5 and L5/S nerve courses were displaced posteriorly compared with the standard position.

Conclusions: The L3/4 and L4/5 nerve roots are located posterior to the vertebral body center. These were found to be offset to the rear when the hip is flexed or the lateral decubitus position is assumed. The present study is the first to elucidate changes in the course of the lumbar nerves as this varies by position. The lateral decubitus position or the position supine with hips flexed may be useful for avoiding nerve damage in a direct lateral transpsoas approach. Preoperative DTI seems to be useful in evaluating the lumbar nerve course as it relates anatomically to the vertebral body.
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http://dx.doi.org/10.1007/s00586-017-5082-yDOI Listing
November 2017