T2* mapping in an equine articular groove model: Visualizing changes in collagen orientation

T2* mapping is promising for the evaluation of articular cartilage collagen. In this work, a groove model in a large animal is used as a model for posttraumatic arthritis. We hypothesized that T2* mapping could be employed to differentiate between healthy and (subtly) damaged cartilage. Eight carpal joints were obtained from four adult Shetland ponies that had been included in the groove study. In this model, grooves were surgically created on the proximal articular surface of the intermediate carpal bone (radiocarpal joint) and the radial facet of the third carpal bone (middle carpal joint) by either coarse disruption or sharp incision. After 9 months, T2* mapping of the entire carpal joint was carried out on a 7.0-T whole-body magnetic resonance imaging (MRI) scanner by means of a gradient echo multi-echo sequence. Afterwards, assessment of collagen orientation was carried out based on Picrosirius Red-stained histological sections, visualized by polarized light microscopy (PLM). The average T2* relaxation time in grooved samples was lower than in contralateral control sites. Opposite to the grooved areas, the “kissing sites” had a higher average T2* relaxation time than the grooved sites. PLM showed mild changes in orientation of the collagen fibers, particularly around blunt grooves. This work shows that T2* relaxation times are different in healthy cartilage vs (early) damaged cartilage, as induced by the equine groove model. Additionally, the average T2* relaxation times are different in kissing lesions vs the grooved sites.     

Biochemical T2* MR quantification of ankle arthrosis in pes cavovarus

Pes cavovarus affects the ankle biomechanics and may lead to ankle arthrosis. Quantitative T2 STAR (T2*) magnetic resonance (MR) mapping allows high resolution of thin cartilage layers and quantitative grading of cartilage degeneration. Detection of ankle arthrosis using T2* mapping in cavovarus feet was evaluated. Eleven cavovarus patients with symptomatic ankle arthrosis (13 feet, mean age 55.6 years, group 1), 10 cavovarus patients with no or asymptomatic, mild ankle arthrosis (12 feet, mean age 41.8 years, group 2), and 11 controls without foot deformity (18 feet, mean age 29.8 years, group 3) had quantitative T2* MR mapping. Additional assessment included plain radiographs and the American Orthopaedic Foot and Ankle Society (AOFAS) score (groups 1 and 2 only). Mean global T2* relaxation time was significantly different between groups 1 and 2 (p = 0.001) and groups 1 and 3 (p = 0.017), but there was no significance for decreased global T2* values in group 2 compared to group 3 (p = 0.345). Compared to the medial compartment T2* values of the lateral compartment were significantly (p = 0.025) higher within group 1. T2* values in the medial ankle joint compartment of group 2 were significantly lower than those of group 1 (p = 0.019). Ankle arthrosis on plain radiographs and the AOFAS score correlated significantly with T2* values in the medial compartment of group 1 (p = 0.04 and 0.039, respectively). Biochemical, quantitative T2* MR mapping is likely effective to evaluate ankle arthrosis in cavovarus feet but further studies are required. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1562–1568, 2010     

Quantitative T2* (T2 star) relaxation times predict site specific proteoglycan content and residual mechanics of the intervertebral disc throughout degeneration

Degeneration alters the biochemical composition of the disc, affecting the mechanical integrity leading to spinal instability. Quantitative T2* MRI probes water mobility within the macromolecular network, a potentially more sensitive assessment of disc health. We determined the relationship between T2* relaxation time and proteoglycan content, collagen content, and compressive mechanics throughout the degenerative spectrum. Eighteen human cadaveric lumbar (L4–L5) discs were imaged using T2* MRI. The T2* relaxation time at five locations (nucleous pulposus or NP, anterior annulus fibrosis or AF, posterior AF, inner AF, and outer AF) was correlated with sulfated‐glycosaminoglycan (s‐GAG) content, hydroxyproline content, and residual stress and strain at each location. T2* relaxation times were significantly correlated with s‐GAG contents in all test locations and were particularly strong in the NP (r = 0.944; p < 0.001) and inner AF (r = 0.782; p < 0.001). T2* relaxation times were also significantly correlated with both residual stresses and excised strains in the NP (r = 0.857; p < 0.001: r = 0.816; p < 0.001), inner AF (r = 0.535; p = 0.022: r = 0.516; p = 0.028), and outer AF (r = 0.668; p = 0.002: r = 0.458; p = 0.041). These strong correlations highlight T2* MRI's ability to predict the biochemical and mechanical health of the disc. T2* MRI assessment of disc health is a clinically viable tool showing promise as a biomarker for distinguishing degenerative changes. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1083–1089, 2014.     

T2* mapping of ovine intervertebral discs: Normative data for cervical and lumbar spine

To obtain T2* values in histologically evaluated healthy ovine intervertebral discs of the cervical and lumbar spine. Intervertebral discs of nine sheep and nine lambs underwent histological assessment with the modified Boos score for grading of disc degeneration. Discs with a score <10 points (maximum = 40 points) underwent T2* mapping (n = 64). Mid‐sagittal T2* values were obtained in five regions: Anterior annulus fibrosus, anterior nucleus pulposus, central nucleus pulposus, posterior nucleus pulposus, and posterior annulus fibrosus. We noted a zonal T2* distribution with high values in the central nucleus and low T2* values in the anterior and posterior annulus fibrosus. The T2* values were higher in lamb than in sheep IVDs for both cervical and lumbar spine (p < 0.001). The T2* values were also higher in the cervical than in the lumbar spine (p = 0.029 for sheep and p < 0.001 for lamb IVDs). The T2* values obtained in these ovine intervertebral discs can serve as baseline values for future T2* measurements both in health and disease. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:717–724, 2016.     

T2* Mapping of the Adult Intervertebral Lumbar Disc: Normative Data and Analysis of Diurnal Effects

In this prospective study, we sought to establish normative data for T2* analysis of lumbar intervertebral discs (IVDs). Further, potential diurnal effects regarding T2* relaxometry of the lower spine were examined. Lumbar IVDs of young, healthy, adult men (n = 20) and women (n = 20; mean age = 24.5 ± 2.9 years) were assessed. Magnetic resonance imaging including T2* mapping was performed on a 3‐T scanner. Mid‐sagittal T2* values were obtained in five regions: anterior annulus fibrosus (AF), anterior nucleus pulposus (NP), central NP, posterior NP, and posterior AF. Zonal and segmental differences, as well as diurnal variations between the T2* analysis in the morning and the evening and effects of unloading, were analyzed. Discs with signs of degeneration on morphological images or imaging artifacts were excluded. We noted a zonal and segmental T2* distribution with high values in the NP, low T2* values in the AF and a T2* increase towards the caudal NP. We observed no diurnal differences between the mean T2* values in the morning and in the evening (p = 0.748). The effect of unloading the spine was low (maximum T2* difference between four measurements = 13.6 ms; significant difference noted only between the 0 and 15‐min measurement). The T2* values obtained in this study will serve as normative values for future T2* measurements. There are no diurnal influences, and we suggest that unloading of the spine has no demonstrable effect after 30 min on the T2* results. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1956–1962, 2019     

Longitudinal 3T MRI T2* mapping of Juvenile osteochondritis dissecans (JOCD) lesions differentiates operative from non-operative patients—Pilot study

Juvenile osteochondritis dissecans (JOCD) is an orthopedic joint disorder of children and adolescents that can lead to premature osteoarthritis. Thirteen patients (mean age: 12.3 years, 4 females), 15 JOCD-affected and five contralateral healthy knees, that had a baseline and a follow-up magnetic resonance imaging (MRI) (mean interval of 8.9 months) and were treated nonoperatively during this interval were included. Retrospectively, patients were assigned to operative or nonoperative groups based on their electronic medical records. Volumetric mean T₂* values were calculated within regions of interest (progeny lesion, interface, parent bone) and region matched control bone in healthy contralateral knees and condyles. The normalized percentage difference of T₂* between baseline and follow up MRI in nonoperative patients significantly increased in progeny lesion (−47.8%, p < 0.001), parent bone (−13.9%, p < 0.001), and interface (−32.3%, p = 0.011), whereas the differences in operative patients were nonsignificant and below 11%. In nonoperative patients, the progeny lesion (p < 0.001) and interface T₂* values (p = 0.012) were significantly higher than control bone T₂* at baseline, but not at follow-up (p = 0.219, p = 1.000, respectively). In operative patients, the progeny lesion and interface T₂* values remained significantly elevated compared to the control bone both at baseline (p < 0.001, p < 0.001) and follow-up (p < 0.001, p < 0.001), respectively. Clinical Significance: Longitudinal T₂* mapping differentiated nonhealing from healing JOCD lesions following initial nonoperative treatment, which may assist in prognosis and improve the ability of surgeons to make recommendations regarding operative versus nonoperative treatment.     

Evaluation of femoral perfusion in a non-traumatic rabbit osteonecrosis model with T2*-weighted dynamic MRI.

We evaluated femoral perfusion in a non-traumatic rabbit serum sickness osteonecrosis (ON) model, using serial repetitive T2*-weighted (T2*W) dynamic magnetic resonance imaging (MRI) and investigated prediction of ON occurrence in early stages, comparing T2*W dynamic MRI with non-enhanced (T2-, T1- and fat suppression T1-weighted) and contrast-enhanced MRI. Early microcirculatory injury or necrotic lesion was detected in 0% of femora (extravasation, 0/6) at 72 h, 33% (necrotic, 4/12) at 1 week and 100% (necrotic, 14/14) at 3 weeks using non-enhanced MRI, and in 67% of femora (extravasation, 4/6) at 72 h, 58% (necrotic, 7/12) at 1 week and 100% (necrotic, 14/14) at 3 weeks using contrast-enhanced MRI. In contrast, microcirculatory injury or necrotic lesion was detected in 83% of femora (extravasation, 5/6) at 72 h, 92% (necrotic, 11/12) at 1 week and 100% (necrotic, 14/14) at 3 weeks using T2*W dynamic MRI as no transient decrease or less marked transient decrease in signal intensity of regions of interest (ROIs), compared to normal femora, which showed a clear transient decrease in signal intensity of ROIs. These results indicate that T2*W dynamic MRI with optimal imaging parameters and a dose of contrast agent is the most sensitive of these three MRI methods and may be clinically useful for evaluating femoral perfusion in artery phase and predicting ON occurrence.     

Cartilage quantitative T2 relaxation time 2–4 years following isolated anterior cruciate ligament reconstruction

Cartilage T2 relaxation time in isolated anterior cruciate ligament reconstruction (ACLR) without concomitant meniscal pathology and their changes over time remain unclear. The purpose of this exploratory study was to: (i) compare cartilage T2 relaxation time (T2 values) in people with isolated ACLR at 2–3 years post‐surgery (baseline) and matched healthy controls and; (ii) evaluate the subsequent 2‐year change in T2 values in people with ACLR. Twenty‐eight participants with isolated ACLR and nine healthy volunteers underwent knee magnetic resonance imaging (MRI) at baseline; 16 ACLR participants were re‐imaged 2 years later. Cartilage T2 values in full thickness, superficial layers, and deep layers were quantified in the tibia, femur, trochlear, and patella. Between‐group comparisons at baseline were performed using analysis of covariance adjusting for age, sex, and body mass index. Changes over time in the ACLR group were evaluated using paired sample t‐tests. ACLR participants showed significantly higher (p = 0.03) T2 values in the deep layer of medial femoral condyle at baseline compared to controls (mean difference 4.4 ms [13%], 95%CI 0.4, 8.3 ms). Over 2 years, ACLR participants showed a significant reduction (p = 0.04) in T2 value in the deep layer of lateral tibia (mean change 1.4 ms [?7%], 95%CI 0.04, 2.8 ms). The decrease in T2 values suggests improvement in cartilage composition in the lateral tibia (deep layer) of ACLR participants. Further research with larger ACLR cohorts divided according to meniscal status and matched healthy cohorts are needed to further understand cartilage changes post‐ACLR. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2022–2029, 2018.

     

正常雌雄大鼠椎间盘微细结构差异的MRI研究

目的 利用T2 mapping和T2*mapping探究雌雄性正常大鼠椎间盘微细结构的差异.方法 选用12只正常成年雌性SD大鼠和10只正常成年雄性SD大鼠,运用T2 mapping和T2*mapping技术对正常大鼠的第6、7尾椎椎间盘C6/7和第7、8尾椎椎间盘C7/8进行扫描,并通过画取感兴趣区域的方法获得相应椎...     

A comparative study of pancreas transplantation between type 1 and 2 diabetes mellitus

BackgroundPancreas transplantation remains the best long-term treatment option to achieve physiological euglycemia and insulin independence in patients with labile diabetes mellitus (DM). It is widely accepted as an optimal procedure for type 1 DM (T1DM), but its application in type 2 DM (T2DM) is not unanimously acknowledged.MethodsIn total, 146 diabetes patients undergoing pancreas transplantation were included in this study. Clinical data and outcomes were compared between the T1DM and T2DM groups.ResultsMajority (93%) of the pancreas transplantations in T2DM were for uremic recipients. Complications occurred in 106 (73%) patients, including 70 (48%) with early complications before discharge and 79 (54%) with late complications during follow-up period. Overall, rejection of pancreas graft occurred in 37 (25%) patients. Total rejection rate in T2DM recipients was significantly lower than that in T1DM. The short- and long-term outcomes for endocrine function in terms of fasting blood sugar and hemoglobin A1c levels and graft survival rates are comparable between the T2DM and T1DM groups.ConclusionsT2DM is not inferior to T1DM after pancreas transplantation in terms of surgical risks, immunological and endocrine outcomes, and graft survival rates. Therefore, pancreas transplantation could be an effective option to treat selected uremic T2DM patients without significant insulin resistance.     

SGLT2抑制剂对2型糖尿病患者骨骼的影响

钠葡萄糖共转运体2(sodium-glucose cotransporter 2,SGLT2)抑制剂是一种新型降糖药物,其作用机理是通过抑制肾小管对尿糖的重吸收,以增加尿糖排泄降低血糖。近期来自国外的多个临床药物试验发现SGLT2抑制剂可能对2型糖尿病患者的骨代谢、骨密度以及骨折率产生影响。本文将通过复习国内外相关研究,尝试综述SGLT2抑制剂对2型糖尿病患者骨骼的影响。     

Possibility of quantitative T2‐mapping MRI of cartilage near metal in high tibial osteotomy: A human cadaver study

T2‐mapping is a widely used quantitative MRI technique in osteoarthritis research. An important challenge for its application in the context of high tibial osteotomy (HTO) is the presence of metallic fixation devices. In this study, we evaluated the possibility of performing T2‐mapping after a HTO, by assessing the extent of magnetic susceptibility artifacts and the influence on T2 relaxation times caused by two commonly used fixation devices. T2‐mapping with a 3D fast spin‐echo sequence at three Tesla was performed on 11 human cadaveric knee joints before and after implantation of a titanium plate and screws (n = 5) or cobalt chrome staples (n = 6). Mean T2 relaxation times were calculated in six cartilage regions, located in the distal and posterior cartilage of femoral condyles and the cartilage of tibial plateaus, both medially and laterally. T2 relaxation times before and after the implantation were compared with paired t‐tests and Wilcoxon rank tests. Due to the extent of the magnetic susceptibility artifact, it was not possible to segment the knee cartilage and thus calculate T2 relaxation times in the lateral weight‐bearing femoral and tibial cartilage regions only in the cobalt chrome group. In all cartilage regions of the titanium implanted knees and those unaffected by artifacts due to cobalt chrome implants, T2 relaxation times did not significantly differ between the two scans. Our results suggest that accurate T2‐mapping after a HTO procedure is possible in all areas after implantation of a titanium fixation device and in most areas after implantation of a cobalt chrome fixation device. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1206–1212, 2018.

     

定量CT对2型糖尿病性骨质疏松的诊断意义

2型糖尿病(type 2 diabetes mellitus, T2DM)通过多种因素影响骨微结构和骨密度,导致骨强度下降,骨折风险增加。定量CT(quantitative computed tomography, QCT)测定三维体积骨密度(volume bone mineral density, vBMD)优于双能X线吸收法(dual energy X-ray absorptiometry, DXA)测定的面积骨密度(area bone mineral density, aBMD)对T2DM患者骨折风险评估,还能发现松质骨的结构改变、皮质骨多孔性结构,对骨量细微改变具有高敏感性。将QCT与有限元分析法结合,通过骨密度、骨组织结构同时分析骨应力来评价骨强度,对T2DM患者骨折风险的预测更有价值。     

Transanal endoscopic microsurgery and radical surgery for T1 and T2 rectal cancer

Background: Transanal endoscopic microsurgery (TEM) has gained increasing acceptance as a local treatment of early rectal cancer. The purpose of this study was to compare the results of TEM and radical surgery in patients with T1 and T2 rectal cancer. Methods: From October 1994 to December 2000, 74 patients with T1 and T2 rectal adenocarcinoma treated with TEM were compared with 100 patients with T1N0M0 and T2N0M0 rectal adenocarcinoma treated with radical surgery. Retrospective analysis was performed regarding to recurrence and survival rate. Neither group received adjuvant chemoradiation. There was no significant difference in age, gender, tumor location, or follow-up period between the two groups. The only difference was in tumor size. Results: Of the 74 patients in TEM group, 52 were T1 (70.3%) and 22 were T2 (29.7%). Of the 100 patients in radical surgery group, 17 were T1 (17%) and 83 patients were T2 (83%). The 5-year local recurrence rates were 4.1% for T1, 19.5% for T2 after TEM, 0% for T1, and 9.4% for T2 after radical surgery. There was no statistical difference between the TEM and radical surgery groups for T1 rectal cancer (p = 0.95), but for T2 rectal cancer, the 5-year local recurrence rate was higher after TEM than after radical surgery (p = 0.04). There were no significant statistical difference between the two groups in terms of the 5-year disease-free survival rate and the survival rate. Conclusions: For T1 rectal cancer, there was no difference in recurrence or 5-year survival rate between the TEM and the radical surgery groups. For T2 rectal cancer, there was no statistical difference in the 5-year survival rate between the two groups, but TEM carried higher risk of local recurrence. Therefore, careful selection of the patients is required for TEM, and when proper muscle invasion is proven, the TEM procedure should be supplemented by further treatment, or radical surgery should be performed. Presented at the Society of American Gastrointestinal Endoscopic Surgeons (SAGES) meeting and the 8th World Congress of Endoscopic Surgery, New York, New York, USA, 13–16 March 2002     

T2图在脊柱结核中的应用价值

目的结合磁共振成像常规序列成像,应用T2弛豫时间图(T2 relaxation time mapping)成像测量脊柱结核病变,分析脊柱结核的特征表现、T2值范围及其诊断价值。方法对病例组25名脊柱结核患者60个病变椎体、自身对照组60个病变临近正常椎体及对照组25名健康志愿者60个正常椎体行脊柱矢状面自旋回波(fast spin echo,FSE)序列8回波扫描,自动生成T2图,并划定感兴趣区(region of interest,ROI)测量T2值。病例组分别与自身对照组和对照组之间采用配对t检验和两独立样本t检验,以P0.01为差异有统计学意义。结果病变椎体及椎旁冷脓肿在T2图上均显示为红绿蓝的混杂色阶,且病变椎体、病变临近正常椎体、对照组正常椎体的T2值分别为(110.32±13.84)ms、(70.06±9.03)ms、(77.29±4.19)ms,病例组分别与自身对照组和对照组之间有统计学差异(P0.01)。结论 T2弛豫时间图技术可以量化评估脊柱结核病变内组织成分的变化,对脊柱结核的诊断及鉴别诊断有一定的指导意义。     

大承气汤对肠源性内毒素血症大鼠组织PLA_2、SOD活性变化的影响

采用静注５－ＨＴ、Ｐｂ－Ａｃｅｔ同时口灌ＬＰＳ对大鼠进行肠源性内毒素血症造模。造模后三小时，测血、组织ＰＬＡ２和ＳＯＤ活性。结果表明，模型组大鼠血清、肺、肝、肾组织匀浆的ＦＬＡ２活性明显高于正常组，而大承气汤治疗组则与正常组无异；相反模型组肺、肝、肾组织匀浆ＳＵＤ活性，则较正常组明显下降，而大承气汤治疗组则与正常组无异，说明大承气汤在肠源性内毒素血症病理形成过程中能明显抑制ＰＬＡ２活性的升高，有益于减轻组织的损害；此外，又可阻止ＳＯＤ活力的下降，从而增强对过量产生的Ｏ２的消除能力。