Magnetic resonance imaging of the weight-bearing spine

Weight-bearing magnetic resonance (MR) imaging of the spine can either be simulated by imaging the patient in the supine position in combination with a special axial loading device or be achieved by using vertically open-configuration MR systems, which allow for in vivo MR images of the spine under upright weight-bearing conditions in either seated or standing body positions. Weight-bearing MRI of the spine permits the study of physiological as well as pathological changes in the relationships of the intervertebral disk, the spinal canal, and the neural foramina as well as the assessment of segmental instability in physiologic body positions. With this technique, MR images may be taken in painful body positions so that morphological changes of the intervertebral disk or other spinal structures may be correlated with pain or other symptoms. In selected cases, weight-bearing MRI of the spine may demonstrate clinically relevant neural compromise or foraminal stenosis, which may be occult on conventional MR images obtained in the supine position.     

Functional MRI of the lumbar spine in erect position in a superconducting open-configuration MR system: Preliminary results

The purpose of this study was to determine the feasibility of obtaining, and findings in, functional MRI of the lumbar spine in an erect position and with flexion and extension. Thirty subjects (including 5 volunteers) were imaged in a sitting position and while performing flexion and extension. The alternations in posterior disk margin, size of neural foramina, and central canal were evaluated. In addition, routine supine imaging was accomplished in 15 of these subjects. The foraminal size and posterior disk margins did not change appreciably from supine to upright position. With extension, there was an increased disk bulge in 27% of disks (40% of those with desiccation). Central canal size (50%) and foraminal size (27%) decreased with extension, especially at levels with disk desiccation. Images obtained with our open-configuration MR unit were diagnostically adequate, although of inferior quality compared with those obtained with a conventional unit. Our preliminary results show the feasibility of obtaining diagnostic images of the erect lumbar spine with flexion and extension. The results are in agreement with those obtained with cadaveric studies. The utility of this method in diagnostic imaging of patients with low back pain remains to be determined.     

腰椎曲度及下腰椎椎间盘高度MSCT负荷前后的比较

目的：对比分析负荷前后MSCT测量的腰椎曲度及下腰椎椎间盘高度变化并与立位X线片对照,检验自制腰椎应力器加压效果。方法：采用自制腰椎应力器对30例腰腿痛患者负荷前后各作一次MSCT扫描,并摄立位X线腰椎侧位平片。在负荷前后Topogram像、负荷前正中矢状面重组图及X线平片上分别测量Th12～S1相邻椎体间夹角、L1与S1夹角、腰椎椎体长度及下腰椎椎间盘高度。在正中矢状面重组图上沿椎间隙夹角平分线重组横轴面图像,测量L3～S1三个椎间隙平面硬膜囊面积并观察椎管内结构变化。结果：负荷前Topogram像与正中矢状面重建像及负荷后Topogram像与X线侧位片上Th12～S1相邻椎体间夹角、L1与S1夹角及腰椎长度、L3～S1椎间盘高度测量结果近乎相等,组间对应测量值比较差异无显著性意义。负荷后L3与L4椎体角显著增大（t=5.36,P〈0.01）,L4与L5、L5与S1椎体角无显著增大（t=2.59,P〉0.05）,其中L4与L5椎体角变化最小。负荷后仅L4-5椎间盘高度显著缩小（t=4.21,P〈0.05）,L3～S1各平面硬膜囊面积均显著缩小,腰椎长度缩短（t=2.37,P〉0.05）,椎间盘膨隆或突出更明显,黄韧带增厚,椎管内结构毗邻关系更密切。结论：自制应力器加压检查能有效模拟人体腰部直立位生理状态情形,对腰椎退变性病变早期诊断及病情的准确评价具有重要意义。     

Please be upstanding – A narrative review of evidence comparing upright to supine lumbar spine MRI

ObjectivesThe objective of the review was to examine the evidence comparing upright to supine MRI of the lumbar spine.Key findingsA literature search identified 14 articles comparing data where subjects had been scanned in both supine and upright positions on the same scanner.Lumbar spine anatomy is dynamic and therefore subject to morphological changes when transitioning from the supine to the upright position. There is strong evidence to suggest structural changes in spinal morphology due to radiographic positioning, and that upright positioning is better for evaluating spondylolisthesis.ConclusionIt has been demonstrated that the scanning position is important in the outcome of the MRI examination of the lumbar spine. With this in mind, it would be beneficial for guidance to be written and adopted to improve the consistency and quality of scanning.Implications for practiceAs upright MRI occupies a niche in the scanning sector, many professionals are unaware of its capabilities. This article aims to increase awareness of the use of upright MRI in evaluating the lumbar spine.     

Axial loaded MRI of the lumbar spine

Magnetic resonance imaging is established as the technique of choice for assessment of degenerative disorders of the lumbar spine. However, it is routinely performed with the patient supine and the hips and knees flexed. The absence of axial loading and lumbar extension results in a maximization of spinal canal dimensions, which may in some cases, result in failure to demonstrate nerve root compression. Attempts have been made to image the lumbar spine in a more physiological state, either by imaging with flexion-extension, in the erect position or by using axial loading. This article reviews the literature relating to the above techniques.     

Intrathecal ligaments and nerve root tension: possible sources of lumbar pain during spaceflight

Lumbar intrathecal ligaments have recently been demonstrated to randomly bind dorsal nerve roots to the dura within the lumbar vertebral column. Lengthening of the vertebral column and associated lumbar back pain experienced by astronauts is common in microgravity. This study was designed to investigate the relationship of lumbar intrathecal ligaments in spinal lengthening as a possible mechanism for back pain. METHODS: A two-part study was designed using 36 vertebral columns from embalmed cadavers. There were 12 vertebral columns studied in mid-sagittal section to demonstrate the possible movement of the spinal cord during lengthening of the vertebral column. The remainder were assessed for the amount of tension placed on a dorsal nerve root by the lumbar intrathecal ligament during lengthening of the vertebral column. RESULTS: The spinal cord moves in a cephalic direction approximately 2.8 mm with 4 cm lengthening of the vertebral column. During lengthening, a loss of thoracic and lordotic curvature was noted with an increase in disk height. Tension was significantly increased on the dorsal nerve roots being tethered by the lumbar intrathecal ligaments in comparison to non-tethered nerve roots during lengthening of the vertebral column. CONCLUSION: A significant amount of tension is placed on dorsal nerve roots tethered by intrathecal ligaments within the lumbar spine during spinal lengthening. These ligaments randomly bind dorsal nerve roots in the lumbar spine and may be involved in the back pain experienced by astronauts in microgravity.     

Positional MR imaging of the lumbar spine: does it demonstrate nerve root compromise not visible at conventional MR imaging?

PURPOSE: To evaluate whether positional magnetic resonance (MR) images of the lumbar spine demonstrate nerve root compromise not visible on MR images obtained with the patient in a supine position (conventional MR images). MATERIALS AND METHODS: Thirty patients with chronic low back pain unresponsive to nonsurgical treatment and with disk abnormalities but without compression of neural structures were included. Positional MR images were obtained by using an open-configuration, 0.5-T MR imager with the patients seated and with flexion and extension of their backs. The disk and nerve root were related to the body position. Nerve root compression and foraminal size were correlated with the patient's symptoms, as assessed with a visual analogue scale. RESULTS: Nerve root contact without deviation was present in 34 of 152 instances in the supine position, in 62 instances in the seated flexion position, and in 45 instances in the seated extension position. As compared with the supine position, in the seated flexion position nerve root deviation decreased from 10 to eight instances; in the seated extension position, it increased from 10 to 13 instances. Nerve root compression was seen in one patient in the seated extension position. Positional pain score differences were significantly related to changes in foraminal size (P =.046) but not to differences in nerve root compromise. CONCLUSION: Positional MR imaging more frequently demonstrates minor neural compromise than does conventional MR imaging. Positional pain differences are related to position-dependent changes in foraminal size.     

Effect of axial loading on neural foramina and nerve roots in the lumbar spine

The hypothesis that the neural foramina in some patients are critically narrowed by axial compression of the spine has not been studied with direct imaging techniques. Frozen cadaveric motion segments of the lumbar spine (intervertebral disk and contiguous vertebrae) were imaged with computed tomography (CT). The segments were thawed and compressed in a hydrostatic press to simulate axial loading, and then the segments were frozen and imaged again. The motion segments were subsequently sectioned with a cryomicrotome, and the chronic degenerative changes present in the disks were classified. Pre- and post-compression CT images were compared, and anatomic relationships were studied. In 41 randomly selected segments (some with preexisting radial, transverse, and concentric annular tears), compression diminished the diameters and cross-sectional areas of the spinal canal and neural foramina. In no cases were nerve roots displaced, distorted, or compressed by axial loading. This study suggests that axial loading, such as that produced by ordinary weight bearing, does not critically compromise the neural foramina even in the presence of chronic degenerative disk changes.     

Physiologic imaging of the spine

Spine imaging poses unique challenges to radiologist and clinician. The dynamic nature of the spine and its mobility across multiple segments is difficult to depict with any single imaging modality. Supine imaging fails to demonstrate the physiologic effects seen with axial load, physiologic posture or positional change. Physiologic imaging begins with standing radiographs. Advanced techniques include axial loading devices on conventional CT or MRI, dynamic (upright) MRI and stereoradiography (EOS). These techniques may unmask dynamic pathology that otherwise would be hidden on conventional supine imaging. Caution must be exercised where such techniques (upright MRI) reduce sensitivity to sinister disease.     

X-ray computed tomographic aspects of lumbar articular synovial cysts with intraspinal development

CT scan imaging findings are described in 22 patients with lumbar spine joint synovial cysts, of intraspinal development, provoking sciatica or lumbosciatica from nerve compression in spinal canal. Diagnosis was suggested by a mass at the posterior joint level, of variable density, sometimes with peripheral calcification, presenting a vacuum appearance on occasions, and with enhanced image with contrast. Differential diagnosis is from excluded hernia and postoperative fibrosis. Posterior intraarticular arthrography can confirm diagnosis and allow treatment with prolonged action corticoid infiltrations.     

腰椎轴向负荷CT检查的临床意义

目的:评估轴向负荷CT检查在腰椎退性行疾病诊断中的临床价值。方法:采用腰大肌放松体位(PRP)和腰椎伸位轴向负荷(ACE)两种体位进行CT检查,进行最大密度投影(MIP)重建,观察加压前后L2～S1各椎间盘中心层面的椎管腔最大横径、纵径及硬膜囊面积的变化,进行比较和统计学分析。结果:对比ACE与PRP体位CT检查,发现ACE体位检查后椎管横径、纵径变小,横截面积变小,均有显著性意义。结论:与PRP体位CT检查比较,ACE体位CT检查获得了更多的放射学诊断信息,可以作为临床诊断椎管狭窄的重要依据,其临床意义优于PRP体位CT检查。     

脊柱支撑器治疗胸腰段骨折脱位（合并或不合并脊髓损伤）

自1981年以来，用脊柱支撑器治疗胸腰段骨折脱位14例，其中11例合并完全或不全脊髓损伤。按脊椎的三柱稳定概念，中柱破坏不稳定者7例。用压缩法及撑开法固定各7例。据生物力学分析，压缩法更符合胸腰段固定的要求，除椎体后缘严重粉碎者外，一般应选用压缩性固定。     

Spine system changes in soldiers after load carriage training in a plateau environment:A prediction model research

Background:Low back pain is the most common spinal disorder among soldiers,and load carriage training (LCT) is considered the main cause.We aimed to investigate changes in the spine system of soldiers after LCT at high altitudes and the change trend of the lumbar spine and surrounding soft tissues under different load conditions.Methods:Magnetic resonance imaging scans of the lumbar spines of nine soldiers from plateau troops were collected and processed.We used ImageJ and Surgimap software to analyze changes in the lumbar paraspinal muscles,intervertebral discs (IVDs),intervertebral foramina,and curvature.Furthermore,the multiple linear regression equation for spine injury owing to LCT at high altitudes was established as the mathematical prediction model using SPSS Statistics version 23.0 software.Results:In the paraspinal muscles,the cross-sectional area (CSA) increased significantly from (9126.4±691.6)mm2 to (9862.7±456.4)mm2,and the functional CSA (FCSA) increased significantly from (8089.6±707.7)mm2 to(8747.9±426.2) mm2 after LCT (P＜0.05);however,the FCSA/CSA was not significantly different.Regarding IVD,the total lumbar spine showed a decreasing trend after LCT with a significant difference (P＜0.05).Regarding the lumbar intervertebral foramen,the percentage of the effective intervertebral foraminal area of L3/4 significantly decreased from 91.6％±2.0％ to 88.1％±2.9％ (P＜0.05).For curvature,the lumbosacral angle after LCT (32.4°±6.8°) was significantly higher (P＜0.05) than that before LCT (26.6°±5.3°),while the lumbar lordosis angle increased significantly from(24.0°±7.1°) to (30.6°±7.4°) (P＜0.05).The linear regression equation of the change rate,ΔFCSA％=-0.718+23.085xload weight,was successfully established as a prediction model of spinal injury after LCT at high altitudes.Conclusion:The spinal system encountered increased muscle volume,muscle congestion,tissue edema,IVD compression,decreased effective intervertebral foramen area,and increased lumbar curvature after LCT,which revealed important pathophysiological mechanisms of lumbar spinal disorders in soldiers following short-term and high-load weight training.The injury prediction model of the spinal system confirmed that a load weight ＜60％ of soldiers' weight cannot cause acute pathological injury after short-term LCT,providing a reference supporting the formulation of the load weight standard for LCT.     

Spinal compression fractures in osteoporotic women: patterns and relationship to hyperkyphosis

A prospective study of thoracic and lumbar spinal fracture distribution and its relationship to thoracic kyphosis was performed in 87 women with osteoporosis. Anterior wedge fractures were most commonly seen in the midthoracic spine and about the thoracolumbar junction, whereas central compression fractures were most common from the first to the fourth lumbar levels. Solitary wedge fractures did not occur above the seventh thoracic vertebra, suggesting that a cause other than osteoporosis must be suspected in any patient with an isolated high thoracic fracture. Analysis of the spinal radiographs obtained in an additional 16 women without osteoporosis revealed that both forms of fracture were unusual in this small group with normal spinal mineralization. The number of anterior wedge fractures in the thoracic spine correlated (r = .546) with the degree of thoracic kyphosis. However, 19% of the women with no thoracic fractures still had thoracic hyperkyphosis. The authors conclude that the hyperkyphosis of osteoporotic women is related to anterior compression fractures but also has contributing nonskeletal factors.     

Isolated posterior pre-marginal hernia. Apropos of 6 cases

Posterior pre-marginal disk hernia, a rare lesion, was diagnosed in six young adults with lumbago. Lateral lumbar spine radiographic images showed an unusual appearance, combining a posterior marginal defect of a vertebral corner and a small bony spicule projecting into lumbar canal. A literature review revealed 27 similar cases, mostly in adolescents. These vertebral disk anomalies are considered by some authors to be fractures of the posterior margin border. A more plausible hypothesis is a pre-marginal hernia, because of lack of a history of injury, the radiologic appearance comparable with that of sequelae of Scheuermann's disease, and the frequent association of these lesions with a spinal growth dystrophy.     

Colpocystoproctography in the upright and supine positions correlated with dynamic MRI of the pelvic floor

PURPOSE: To test whether there are statistically significant differences between measurement results on colpocystoproctography in the upright and the supine positions, and to correlate these results with dynamic MRI. PATIENTS AND METHODS: Seven patients with pelvic floor descent had received colpocystoproctography in the upright and supine positions and, additionally, dynamic MRI of the pelvic floor. Bladder neck position, angle of urethral inclination, posterior vesicourethral angle, and vaginal vault position were measured at relaxed pelvic floor and at pelvic strain. Differences between the measurement results of each parameter in the upright and supine position on colpocystoproctography were calculated and correlated with the measurement results from the dynamic MRI. RESULTS: At pelvic strain, bladder neck position, angle of urethral inclination, posterior vesicourethral angle and vaginal vault position measurements showed no statistically significant differences between colpocystoproctography in the upright and supine positions or dynamic MRI. For the bladder neck height at pelvic floor relaxation, significant differences were found between colpocystoproctography in the upright and supine positions, and colpocystoproctography in the upright position versus dynamic MRI. CONCLUSION: At pelvic strain, measurement data from dynamic MRI are not statistically different from data from colpocystoproctography either in supine and upright positions.     

使用U-Net深度学习网络对腰椎矢状T2WI图像自动分割的可行性研究

目的:研究训练U-Net模型自动分割腰椎矢状面T₂WI图像中各结构的可行性。方法:回顾性搜集腰椎矢状面T2WI图像数据,共获得80个矢状面T₂WI序列。由2位影像医师手工标注矢状面腰椎椎体、椎间盘、椎间孔、椎管/硬膜囊、脊髓及马尾神经。将数据随机分为训练集、调优集和测试集,使用U-Net网络分两步(coarse-to-fine)训练腰椎矢状T₂WI分割模型。模型评价指标包括客观评估(Dice系数)和主观评估。结果:11例测试集数据中U-Net模型预测腰椎5个解剖部位分割的Dice值分别为椎体0.82~0.9(平均0.864)、椎间盘0.86~0.92(平均0.898)、椎管/硬膜囊0.76~0.87(平均0.837)、椎间孔0.6~0.76(平均0.67)、脊髓及马尾神经0.55~0.9(平均0.669)。主观评估各解剖部位分割满意率分别为椎体97.5%、椎间盘97.9%、椎管/硬膜囊86.4%、椎间孔76.7%、脊髓及马尾神经78.6%。结论:基于U-Net深度学习网络对腰椎矢状T₂WI图像的解剖结构进行自动分割是可行的。     

Gastroesophageal reflux studies using milk in infants and children--the need for multiple views

The aim of this study was to assess the value of multiple acquisitions in detecting position-related gastroesophageal reflux (GER). We retrospectively reviewed milk scans of 105 patients with suspected GER and possible lung complications. After 2 h of fasting, 11.4 MBq Tc-99m-sulfur colloid was given to the patient orally along with formula or milk (infants). Without sedation in most patients, serial images (30 s each for 15 frames=8 min) were acquired in the supine, prone, right-side down, and left-side down positions. If reflux was detected in one position, before proceeding to the next position the patient was given water or milk to clear the esophagus.The study was considered positive if the activity reappeared in the esophagus. Anterior and posterior chest images were obtained after a delay of 2-4 h to detect any pulmonary aspiration. A total of 59 patients (56.2%) tested negatively for GER in all four positions and also showed a negative delayed scan for pulmonary aspiration. In contrast, 46 patients tested positively for GER in variable positions (prone=4, supine=6, left-side down=3, right-side down=12, and in more than one position=21, of which six included the supine position). The percentage yield of a positive GER position-related technique was three-fold that of conventional single supine position. These results may aid a better understanding of the pathophysiology of the disease and the design of preventive and therapeutic measures.     

Changes in cross-sectional measurements of the spinal canal and intervertebral foramina as a function of body position: in vivo studies on an open-configuration MR system

OBJECTIVE: The purpose of this study was to evaluate physiologic changes of the cross-sectional area of the spinal canal and neural foramina in young asymptomatic volunteers. SUBJECTS AND METHODS: Twelve asymptomatic volunteers were examined in a 0.5-T open-configuration MR system. T2-weighted fast spin-echo sequences were obtained in upright neutral, upright flexed, upright extended, and supine extended positions. The cross-sectional area of the spinal canal and the thickness of the ligamentum flavum were measured on angled axial images at the L4-L5 level. The anteroposterior diameter of the spinal canal and cross-sectional areas of the neural foramina were measured on sagittal images from L1 to S1. RESULTS: At disk level, the cross-sectional area of the spinal canal varied significantly between body positions, most notably between the upright flexed (mean, 268 mm2) and the upright extended (mean, 224 mm2) positions (p < .0001). The maximum thickness of the ligamenta flava increased in the extended positions (p < .0001). The cross-sectional area of the neural foramina underwent position-dependent variations of as much as 44.4%. The smallest cross-sectional areas were found in the extended positions. CONCLUSION: In asymptomatic volunteers, MR imaging is able to show position-dependent changes in the cross-sectional areas of the spinal canal and the intervertebral foramina. The extended positions best reveal important findings.     

Intervertebral disk calcification of the spine in an elderly population: radiographic prevalence, location, and distribution and correlation with spinal degeneration

PURPOSE: To determine the prevalence, distribution, and location of intervertebral disk calcification (IDC) in the thoracic and lumbar spine and the association of IDC with radiographically evident spinal degenerative changes in cadavers. MATERIALS AND METHODS: Anterior vertebral columns comprising T1 through L5 were removed from 223 cadavers (183 men, 40 women; mean age at death, 67 years; range, 37-94 years). Approximately 5-mm-thick parasagittal sections were investigated with high-contrast radiography. The presence of IDC, osteophytes, vertebral endplate abnormalities, and vacuum phenomena was recorded, and the height of disk space was measured at 3,568 intervertebral levels. Logistic regression analysis was performed. RESULTS: IDC was identified in 178 (80%) of the 223 cadavers. Of 3,568 disks, 459 (13%) had IDC, and 289 cases (63%) were located in the annulus fibrosus. IDC was most common in the lower thoracic spine, occurring in 275 (60%) of 459 disks. IDC occurred in 159 (87%) of 183 men and 19 (48%) of 40 women. Logistic regression analysis was adjusted for age, and results showed that the frequency of IDC was significantly higher in men in upper, middle, and lower segments of the thoracic spine (P <.05) but not in the lumbar spine (P =.09). IDC correlated with increasing age (P <.001) and disk space loss (P <.001) at all spinal levels. There was no association of IDC with vacuum phenomena or vertebral endplate abnormalities at any spinal level. CONCLUSION: IDC is common in elderly persons, especially in the annulus fibrosus and lower thoracic spine. The prevalence of IDC increases with age and extent of disk space loss.