Nonmagnetic J=0 State and Spin-Orbit Excitations in K_{2}RuCl_{6}.

Spin-orbit Mott insulators composed of t_{2g}^{4} transition metal ions may host excitonic magnetism due to the condensation of spin-orbital J=1 triplons. Prior experiments suggest that the 4d antiferromagnet Ca_{2}RuO_{4} embodies this notion, but a J=0 nonmagnetic state as a basis of the excitonic picture remains to be confirmed. We use Ru L_{3}-edge resonant inelastic x-ray scattering to reveal archetypal J multiplets with a J=0 ground state in the cubic compound K_{2}RuCl_{6}, which are well described within the LS-coupling scheme. This result highlights the critical role of unquenched orbital moments in 4d-electron compounds and calls for investigations of quantum criticality and excitonic magnetism on various crystal lattices.

Prenatal and adult androgen activities in alcohol dependence.

OBJECTIVE: Alcohol dependence is more prevalent in men than in women. The evidence for how prenatal and adult androgens influence alcohol dependence is limited. We investigated the effects of prenatal and adult androgen activity on alcohol dependence. Moreover, we studied how the behaviours of pregnant women affect their children's prenatal androgen load. METHOD: We quantified prenatal androgen markers (e.g., second-to-fourth finger length ratio [2D : 4D]) and blood androgens in 200 early-abstinent alcohol-dependent in-patients and 240 controls (2013-2015, including a 12-month follow-up). We also surveyed 134 women during pregnancy (2005-2007) and measured the 2D : 4D of their children (2013-2016). RESULTS: The prenatal androgen loads were higher in the male alcohol-dependent patients compared to the controls (lower 2D : 4D, P = 0.004) and correlated positively with the patients' liver transaminase activities (P < 0.001) and alcohol withdrawal severity (P = 0.019). Higher prenatal androgen loads and increasing androgen levels during withdrawal predicted earlier and more frequent 12-month hospital readmission in alcohol-dependent patients (P < 0.005). Moreover, stress levels (P = 0.002), alcohol (P = 0.010) and tobacco consumption (P = 0.017), and lifetime stressors (P = 0.019) of women during pregnancy related positively to their children's prenatal androgen loads (lower 2D : 4D). CONCLUSION: Androgen activities in alcohol-dependent patients and behaviours of pregnant women represent novel preventive and therapeutic targets of alcohol dependence.

Structural phase transitions on AgCuS stromeyerite mineral under compression.

The structural behavior of mineral Stromeyerite, AgCuS, has been studied by means of angle-dispersive X-ray diffraction measurements up to 13 GPa and ab initio total-energy calculations. Two high-pressure phase transitions are found at 1.4 and 5.7 GPa, from the initial distorted Ni(2)In-type phase (AuRbS-type, RP, space group Cmc2(1)) through an anti-PbClF-type phase (HP1, space group P4/nmm) to a monoclinic distortion of this latter phase (HP2, space group P2(1)/m). The collapse of the metal-metal interatomic distances at the RP-HP1 transition suggests a stronger metallic behavior of the high-pressure phase. The compressibility of the lattice parameters and the equation of state of the first pressure-induced phase have been experimentally determined. First-principles calculations present an overall agreement with the experimental results in terms of the high-pressure sequence and provide chemical insight into the AgCuS behavior under hydrostatic pressure.

Sphingolipids in psychiatric disorders and pain syndromes.

Despite the high prevalence and devastating impact of psychiatric disorders, little is known about their etiopathology. In this review, we provide an overview on the participation of sphingolipids and enzymes responsible for their metabolism in mechanisms underlying psychiatric disorders. We focus on the pathway from sphingomyelin to proapoptotic ceramide and the subsequent metabolism of ceramide to sphingosine, which is in turn phosphorylated to yield anti-apoptotic sphingosine-1-phosphate (S1P).The sphingomyelinase/ceramide system has been linked to effects of reactive oxygen species and proinflammatory cytokines in the central nervous system as well as to synaptic transmission. Compared to ubiquitously expressed acid sphingomyelinase, acid and neutral ceramidase and neutral sphingomyelinase are highly active in brain regions. Depressed patients show elevated plasma ceramide levels and increased activities of acid sphingomyelinase which is functionally inhibited by many anti-depressive drugs. Exposure to alcohol is associated with an activation of acid and neutral sphingomyelinase observed in cell culture, mouse models and in alcohol-dependent patients and with increased concentrations of ceramide in various organs.Levels of sphingomyelin and ceramide are altered in erythrocytes and post-mortem brain tissues of schizophrenic patients in addition to changes in expression patterns for serine palmitoyltransferase and acid ceramidase leading to impaired myelination. After induction of anxiety-like behavior in animal models, higher serum levels of S1P were reported to lead to neurodegeneration. Correspondingly, S1P infusion appeared to increase anxiety-like behavior. Significantly upregulated levels of the endogenous ceramide catabolite N,N-dimethylsphingosine were observed in rat models of allodynia. Conversely, rats injected intrathecally with N,N-dimethylsphingosine developed mechanical allodynia. Moreover, S1P has been implicated in spinal nociceptive processing.The increasing interest in lipidomics and improved analytical methods led to growing insight into the connection between psychiatric and neurological disorders and sphingolipid metabolism and may once provide new targets and strategies for therapeutic intervention.

Chondrogenic differentiation of growth factor-stimulated precursor cells in cartilage repair tissue is associated with increased HIF-1alpha activity.

OBJECTIVE: To investigate the chondrogenic potential of growth factor-stimulated periosteal cells with respect to the activity of Hypoxia-inducible Factor 1alpha (HIF-1alpha). METHODS: Scaffold-bound autologous periosteal cells, which had been activated by Insulin-like Growth Factor 1 (IGF-1) or Bone Morphogenetic Protein 2 (BMP-2) gene transfer using both adeno-associated virus (AAV) and adenoviral (Ad) vectors, were applied to chondral lesions in the knee joints of miniature pigs. Six weeks after transplantation, the repair tissues were investigated for collagen type I and type II content as well as for HIF-1alpha expression. The functional role of phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) and mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling on BMP-2/IGF-1-induced HIF-1alpha expression was assessed in vitro by employing specific inhibitors. RESULTS: Unstimulated periosteal cells formed a fibrous extracellular matrix in the superficial zone and a fibrocartilaginous matrix in deep zones of the repair tissue. This zonal difference was reflected by the absence of HIF-1alpha staining in superficial areas, but moderate HIF-1alpha expression in deep zones. In contrast, Ad/AAVBMP-2-stimulated periosteal cells, and to a lesser degree Ad/AAVIGF-1-infected cells, adopted a chondrocyte-like phenotype with strong intracellular HIF-1alpha staining throughout all zones of the repair tissue and formed a hyaline-like matrix. In vitro, BMP-2 and IGF-1 supplementation increased HIF-1alpha protein levels in periosteal cells, which was based on posttranscriptional mechanisms rather than de novo mRNA synthesis, involving predominantly the MEK/ERK pathway. CONCLUSION: This pilot experimental study on a relatively small number of animals indicated that chondrogenesis by precursor cells is facilitated in deeper hypoxic zones of cartilage repair tissue and is stimulated by growth factors which enhance HIF-1alpha activity.

High-dose treatment with (186)Re-HEDP or (153)Sm-EDTMP combined with amifostine in a rabbit model.

UNLABELLED: The aim of this experimental study was to investigate the myeloprotective potential of amifostine in rabbits receiving high-dose treatment with either (153)Sm-ethylenediaminetetramethylene phosphonate (EDTMP) or (186)Re-hydroxyethylidene diphosphonate (HEDP) and to check for drug interactions impairing the skeletal uptake of these radiopharmaceuticals by amifostine. METHODS: To a total of 24 rabbits, we administered 1,000 MBq of either (153)Sm-EDTMP (n = 12) or (186)Re-HEDP (n = 12). Six animals of each group received 500 mg amifostine intravenously 10-15 min before injection of the radiopharmaceutical, whereas the other 6 animals served as controls. Up to 8 wk after treatment, blood samples were collected every 3-5 d to measure platelet and leukocyte counts. Furthermore, whole-body images were acquired at 3 min, 3 h, and 24 h after injection of the radiopharmaceutical to quantify the skeletal uptake. RESULTS: For (186)Re-HEDP, the mean decrease in platelets was significantly less in the amifostine group (35.5% +/- 2.4%) than in the control group (61.3% +/- 5.4%, P < 0.001). Similar results were found for (153)Sm-EDTMP (36.5% +/- 8.3% vs. 52.3% +/- 14.0%, P < 0.05). No significant differences in leukocyte counts were found for (186)Re-HEDP (75.3% +/- 12.3% in the amifostine group and 72.5% +/- 4.1% in the control group, P > 0.05), whereas rabbits treated with (153)Sm-EDTMP plus amifostine showed a significantly greater decrease in leukocytes (69.2% +/- 10.8%) than did the control group (56.6% +/- 4.0%, P < 0.05). Bone uptake in percentage of initial total whole-body activity was significantly decreased in animals treated with amifostine compared with the control groups for both (186)Re-HEDP (15.8% +/- 3.1% vs. 30.9% +/- 1.9%, P < 0.001) and (153)Sm-EDTMP (31.7% +/- 8.9% vs. 44.0% +/- 6.5%, P < 0.05). CONCLUSION: For amifostine, we found a highly significant cytoprotective effect on platelets but no leukoprotective effect. The latter probably relies on the intrinsic myelotoxicity of high-dose amifostine, which seemed to potentiate the leukodepression of the radiopharmaceuticals. The lower bone uptake in amifostine-treated animals may be caused by the chemical structure of amifostine, which is a potentially complex-forming compound that may be able to displace bisphosphonates from the rhenium- and samarium-bisphosphonate complexes, resulting in altered biodistribution patterns.

Effect of intraarticular pressure on patellar position. Computed tomography study in cadaveric specimens.

RATIONALE AND OBJECTIVES: The purpose of the study was to evaluate the effect of articular fluid distention on patellar position at different degrees of knee angulation. METHODS: Patellar position in 10 cadaveric knee specimens was determined with 30, 100, and 200 mm Hg joint distention at 45, 20, and 5 degrees of knee flexion using computed tomography. Patellar tilting and lateromedial and anteroposterior displacement of the patellar position were analyzed. RESULTS: Lateral tilting increased with greater articular distention and decreasing knee flexion. At 5 degrees of flexion and 200 mm Hg of distention, change in lateral tilting ranged from -7 to +5 degrees. At 45 degrees of flexion and increased distention, the patellar shift ranged from 6 mm medialization to 1 mm lateralization for 200 mm Hg, but the patellar position was more variable at 5 degrees of flexion with increasing intraarticular pressure (range 7 mm medialization to 8 mm lateralization). With increasing articular pressure the patellae were increasingly displaced anteriorly with the most pressure-dependent changes at 45 and 20 degrees of knee flexion. CONCLUSIONS: Fluid distentions of the knee joint have unpredictable and varying effects on the patellar position and vary considerably among persons. When judging patellar position during arthroscopy and in patients with large joint effusions, the arthroscopist and radiologist should be aware of these effects.

Dynamic changes of the spinal canal in patients with cervical spondylosis at flexion and extension using magnetic resonance imaging.

RATIONALE AND OBJECTIVES: The authors determine the dynamic changes of the spinal canal during flexion and extension in patients with cervical spondylosis. METHODS: Forty-six patients were studied inside a whole-body magnetic resonance (MR) scanner with between 50 degrees of flexion and 30 degrees of extension, using a positioning device. At neutral position (0 degree) and maximum flexion and extension sagittal T2-weighted turbo spin echo sequences were acquired. RESULTS: A significant (P < or = 0.05) increase of spinal stenosis was found at extension (48%, 22 of 46 patients) when compared with flexion (24%, 11 of 46). Cervical cord compression was diagnosed at flexion in 5 patients (11%) and at extension in 9 patients (20%). Concerning the number of patients with cervical cord compression at flexion and extension, significant differences (P < or = 0.05) were found in patients with degenerative changes at four segments compared with patients with one segment involvement. CONCLUSIONS: Magnetic resonance imaging identified a significant percentage of increased spinal stenosis at flexion and, especially, at extension, which was not observed at neutral position (0 degree). Flexion and extension MR imaging demonstrates additional information using a noninvasive technique concerning the dynamic factors in the pathogenesis of cervical spondylotic myelopathy.

Application of the maximum entropy method for evaluating phosphorus-31-magnetic resonance spectra in patients with liver metastases.

RATIONALE AND OBJECTIVES: The clinical feasibility and application of the maximum entropy method for data analysis from in vivo phosphorus-31-magnetic resonance (P-31-MR) spectra of the liver were determined. METHODS: Image-guided localized P-31-MR spectroscopy was performed in 24 patients with liver metastases and in 20 healthy volunteers. The spectra were obtained with a whole body scanner operating at 1.5 T using a surface coil. Phosphomonoester/beta-adenosine triphosphate (ATP), phosphodiester/beta-ATP, and inorganic phosphate/beta-ATP were calculated from the maximum entropy method-spectra and from spectra evaluated with standard data processing (Fourier transformation spectra). RESULTS: Phosphomonoester/beta-ATP and phosphodiester/beta-ATP were increased significantly with both methods in patients' spectra. Maximum entropy method spectra showed a distinct pattern with low noise. It was easier to determine peak borders and to attach resonances to the different metabolites using this method. CONCLUSIONS: Maximum entropy method is an alternative method for evaluation and quantification of P-31-MR spectra data and is preferred to standard data processing with Fourier transformation in cases of reduced signal-to-noise ratio of spectra.

In vivo P-31-MR-spectroscopy of focal hepatic lesions. Effectiveness of tumor detection in clinical practice and experimental studies of surface coil characteristics and localization technique.

RATIONALE AND OBJECTIVES: The influence of partial tumor sampling in a volume of interest (VOI) on the ratios of phosphorus metabolites was examined by localized phosphorus magnetic resonance spectroscopy (P-31-MRS). Experiments were performed to investigate the characteristics of the surface coil used and precession of spatial localization. METHODS: A total of 24 patients with liver metastases and 20 volunteers were studied by P-31-MRS. Patients were divided in two groups: VOI < 50% (n = 8) and VOI > 50% (n = 16) occupied by tumor. For evaluation of the surface coil and localization method (image selected in vivo spectroscopy), phantom studies were performed. RESULTS: Superficial focal liver tumors were detectable with a surface coil at a distance within the coil radius. The image selected in vivo spectroscopy permitted the study of phosphorus metabolism in a defined VOI, phosphomonoester/beta-adenosine triphosphate and phosphodiester/beta-adenosine triphosphate were elevated significantly in spectra of both patient groups. CONCLUSIONS: Detection of small tumor volumes within a VOI filled by less than 50% of the tumor is possible, with results statistically different from that in normal volunteers.

The total entropy for evaluating 31P-magnetic resonance spectra of the liver in healthy volunteers and patients with metastases.

RATIONALE AND OBJECTIVES: The authors describe the clinical status of liver tissue with only a single numerical quantity (total entropy) derived from spectroscopic data of 31P-magnetic resonance (MR) spectra. METHODS: Twenty-four patients with liver metastases and 20 volunteers were investigated with image-guided volume selective 31P-MR spectroscopy on a 1.5-T whole body scanner. From each in vivo 31P-MR spectrum, the ratios of phosphomonoester (PME)/beta-adenosine triphosphate (ATP), inorganic phosphate (Pi)/beta-ATP and phosphodiester (PDE)/ beta-ATP and the total entropy (H*) were calculated. Mean values and standard deviations were determined and significance of the differences were tested with Student's t test. RESULTS: For patients, the H* = 4.7 +/- 4.3, PME/beta-ATP 0.72 +/- 0.28, Pi/beta-ATP = 1.00 +/- 0.39, PDE/beta-ATP = 1.68 +/- 0.59. For the volunteers, H* = 7.6 +/- 2.5, PME/beta-ATP = 0.39 +/- 0.15, Pi/beta-ATP = 0.90 +/- 0.19, PDE/beta-ATP = 1.25 +/- 0.28. The total entropy of patients' spectra showed significantly lower values compared with those of volunteers. PME/beta-ATP and PDE/beta-ATP of the patients increased and differed significantly from volunteer data. CONCLUSIONS: It was demonstrated that the results of in vivo 31P-MR spectroscopy may be described with a single criterion by means of the total entropy.

Transverse ligament and its effect on meniscal motion. Correlation of kinematic MR imaging and anatomic sections.

RATIONALE AND OBJECTIVES: To evaluate the effect of the transverse ligament on translation of the menisci. METHODS: Six cadaveric knees were examined by MR imaging inside a positioning device before and after transecting the transverse ligament. The knees were examined at various positions: extension, 30 degrees of flexion, 60 degrees of flexion, and full flexion. Sagittal T1-weighted spin-echo images were generated at each knee position and evaluated for statistical differences with regard to anterior-posterior meniscal excursion. RESULTS: Statistically significant differences in meniscal excursion were found before and after transsecting the transverse ligament for anterior-posterior meniscal motion of the anterior horn of the medial meniscus at 30 degrees of knee flexion. No such significant differences were found, however, at 60 degrees of flexion and full flexion in anterior-posterior meniscal excursion of the anterior or posterior horn of either meniscus before and after transsecting the transverse ligament. CONCLUSIONS: The transverse ligament has a restricting effect on anterior-posterior excursion of the anterior horn of the medial meniscus at lower degrees of knee flexion.

Evaluation of the triangular fibrocartilage and the scapholunate and lunotriquetral ligaments in cadavers with low-field-strength extremity-only magnet. Comparison of available imaging sequences and macroscopic findings.

RATIONALE AND OBJECTIVES: The authors assessed the ability of a low-field-strength extremity-only magnet to provide visualization of the triangular fibrocartilage and the scapholunate and lunotriquetral ligaments. METHODS: Twelve human wrists were examined with a 0.2 T extremity-only magnet. T1-weighted spin echo, proton density-weighted, and T2-weighted turbo spin echo, short-tau inversion recovery, and three-dimensional gradient recalled echo images were acquired, and sections of the specimens were then made that corresponded to the magnetic resonance images. Masked imaging analyses were correlated with macroscopic and limited histopathologic findings. RESULTS: Low-field-strength extremity-only magnet allowed consistent visualization of the triangular fibrocartilage and accurate assessment of a small number of complete tears of the triangular fibrocartilage. The scapholunate ligaments in all cases were identified using a combination of imaging sequences. Consistent visualization of the lunotriquetral ligament with a low-field-strength extremity magnet was difficult. CONCLUSIONS: Magnetic resonance imaging with a low-field-strength extremity-only magnet can be used to visualize the triangular fibrocartilage and the scapholunate ligament, but not the lunotriquetral ligament.

Exacerbated pain in cervical radiculopathy at axial rotation, flexion, extension, and coupled motions of the cervical spine: evaluation by kinematic magnetic resonance imaging.

RATIONALE AND OBJECTIVES: The authors evaluate the functional changes in patients with cervical radiculopathy and increasing symptoms after provocative maneuvers at flexion, extension, axial rotation, and coupled motions of the cervical spine. METHODS: Twenty-one patients with cervical disc herniation (n = 17) or cervical spondylosis (n = 4) in whom symptoms were elicited at flexion, extension, axial rotation, and coupled motions of the cervical spine were studied. The patients were examined inside a positioning device by using a circular surface coil for signal reception. At neutral position (0 degrees) and at provocative positions sagittal T2-weighted turbo spin-echo, axial T2-weighted two-dimensional flash sequence, sagittal three-dimensional (3D) fast imaging with steady state precision sequence and coronal 3D double-echo-in-the-steady-state sequences were obtained. The 3D sequences were reformatted in the axial and oblique coronal planes perpendicular to the exiting nerve roots. The images were evaluated for the size of disc herniations, the foraminal size and cervical cord rotation or displacement at provocative position compared with neutral position (0 degrees). RESULTS: Compared with neutral position (0 degrees), change in size of disc herniation was not found in any (0%) of the provocative positions. In five (24%) patients cervical cord rotation or displacement was noted at axial rotation. The foraminal size increased at flexion, axial rotation to the opposite side of pain and flexion combined with axial rotation to the opposite side of the pain. The foraminal size decreased at extension combined with axial rotation to the side of the pain. A decrease or no change in foraminal size was observed at either extension or axial rotation to the side of the pain. CONCLUSIONS: In patients with cervical disc herniation or cervical spondylosis, exacerbated pain at defined provocative maneuvers is related more to changes in the foraminal size and to nerve root motion with, in some cases, cervical cord rotation or displacement than to changes in the size of herniated discs.

Classification system based on kinematic MR imaging in cervical spondylitic myelopathy.

BACKGROUND AND PURPOSE: Functional myelographic studies are often used to evaluate the dynamic changes of the cervical spinal canal during flexion and extension. The purposes of this study were to use kinematic MR imaging to assess the dynamic changes of the cervical spine in patients at different stages of degenerative disease and to describe a classification system based on static and dynamic factors in the pathogenesis of cervical spondylitic myelopathy. METHODS: Eighty-one patients with different stages (I-IV) of degenerative disease of the cervical spine were examined with MR imaging. In the neutral position (0 degrees) and at maximum flexion and extension, spinal stenosis was classified for each segment according to the following grading system: 0 = normal, 1 = partial obliteration of the anterior or posterior subarachnoid space, 2 = complete obliteration of the anterior or posterior subarachnoid space, and 3 = cervical cord compression or displacement. RESULTS: At flexion and extension, the prevalence of spinal stenosis and cervical cord impingement increased as the stage of degenerative disease progressed. With regard to a pincer effect (anterior and posterior cord impingement) and cord encroachment at multiple segments, statistically significant differences were observed at stages III and IV as compared with stages I and II. Significant increase in cord impingement was seen in 22 (27%) of 81 patients at extension, as compared with four (5%) of 81 patients at flexion. CONCLUSION: Regardless of the stage of degenerative disease and grade of spinal stenosis at the neutral position (0 degrees), cervical spinal motion may contribute to the development of cervical spondylitic myelopathy.

Motion-triggered cine MR imaging of active joint movement.

MRI cine studies of active physiological joint movement can provide additional functional information as a supplement to standard examinations. With the ankle joint as an example, it is shown that it is possible to measure kinematic MRI presentations of active joint movement. A pneumatic pressure transducer, a respiratory monitor, and an active differentiator transformed the skin muscle shifting of periodically performed joint movement to a pseudo-ECG, which finally triggered the MRI scanner as in cardiac cine MR imaging.

In vivo changes in the neuroforaminal size at flexion-extension and axial rotation of the cervical spine in healthy persons examined using kinematic magnetic resonance imaging.

STUDY DESIGN: In vivo flexion-extension and axial rotation magnetic resonance imaging (MRI) studies of the cervical spine were performed inside a positioning device. OBJECTIVE: To determine the functional changes of neuroforaminal size that occur during flexion-extension and axial rotation of the cervical spine in healthy persons. SUMMARY OF BACKGROUND DATA: Kinematic MRI studies of the cervical spine were performed to obtain detailed information about the functional changes that occur in neuroforaminal size during flexion-extention and axial rotation. The results were compared with published data of in vitro functional flexion-extension and axial rotation studies of the cervical spine. METHODS: Inside a positioning device, the cervical spines of 30 healthy persons were examined in a whole-body magnetic resonance scanner from 40 degrees of flexion to 30 degrees of extension at nine different angle positions. In addition, axial rotation was performed at neutral position (0 degrees ) and at 20 degrees and 40 degrees of axial rotation to both sides. The images were analyzed with respect to the neuroforaminal size at each position using a reformatted 3D-FISP sequence. RESULTS: At flexion, widening of the neuroforaminal size of up to 31% (compared with neutral position, 0 degrees ) was observed. Conversely, at extension a decrease in the size of the neuroforamen of up to 20% was recognized. At 20 degrees and 40 degrees of ipsilateral rotation of the head, a reduction in the neuroforaminal size of up to 15% and 23%, respectively, compared with the neutral position was noted. In contrast, a widening of the foraminal size was recognized on the contralateral side of 9% and 20% at 20 degrees and 40 degrees rotation. Statistically significant differences (p <== 0.05) were found in the neuroforaminal size between different degrees of flexion and extension and in addition for axial rotation compared to neutral position (0 degrees ). CONCLUSION: Compared with the results of previous biomechanical studies of human cadaver cervical spines, kinematic MRI provides additional noninvasive data concerning the physiological changes of the neuroforaminal size during flexion-extension and axial rotation in healthy individuals.

Biomechanical aspects of the subarachnoid space and cervical cord in healthy individuals examined with kinematic magnetic resonance imaging.

STUDY DESIGN: In vivo flexion-extension magnetic resonance imaging studies of the cervical spine were performed inside a positioning device. OBJECTIVE: To determine the functional changes of the cervical cord and the subarachnoid space that occur during flexion and extension of the cervical spine in healthy individuals. SUMMARY OF BACKGROUND DATA: As an addition to static magnetic resonance imaging examinations, kinematic magnetic resonance imaging studies of the cervical spine were performed to obtain detailed information about functional aspects of the cervical cord and the subarachnoid space. The results were compared with published data of functional flexion-extension myelograms of the cervical spine. METHODS: The cervical spines of 40 healthy individuals were examined in a whole-body magnetic resonance scanner from 50 degrees of flexion to 30 degrees of extension, using a positioning device. At nine different angle positions, sagittal T1-weighted spin-echo sequences were obtained. The images were analyzed with respect to the segmental motion, the diameter of the subarachnoid space, and the diameter of the cervical cord. RESULTS: The segmental motion between flexion and extension was 11 degrees at C2-C3, 12 degrees at C3-C4, 15 degrees at C4-C5, 19 degrees at C5-C6, and 20 degrees at C6-C7. At flexion, a narrowing of the ventral subarachnoid space of up to 43% and a widening of the dorsal subarachnoid space of up to 89% (compared with the neutral position, 0 degrees) were observed. At extension, an increase in the diameter of the ventral subarachnoid space of up to 9% was observed, whereas the dorsal subarachnoid space was reduced to 17%. At flexion, there was a reduction in the sagittal diameter of the cervical cord of up to 14%, and, at extension, there was an increase of up to 15%, compared with the neutral position (0 degrees; these values varied depending on the cervical segment. Statistically significant differences (P < 0.05) were found between flexion and extension in the diameter of the ventral and dorsal subarachnoid space and in the diameter of the cervical cord. CONCLUSIONS: Compared with the results of previous studies using functional cervical myelograms, kinematic magnetic resonance imaging provides additional noninvasive data concerning the physiologic changes of the cervical subarachnoid space and the cervical cord during flexion and extension in healthy individuals.

Effect of a patellar realignment brace on patients with patellar subluxation and dislocation. Evaluation with kinematic magnetic resonance imaging.

The object of this study was to evaluate the effect of a patellar realignment brace on patients with patellar subluxation or dislocation. Twenty-one patients (24 patellofemoral joints) with clinical evidence of patellar subluxation (N = 16) or dislocation (N = 5) were examined with the joint inside a positioning device to allow active-motion, kinematic magnetic resonance imaging. To analyze the patellar tracking pattern, the same imaging parameters (patellar tilt angle, bisect offset, and lateral patellar displacement) and section locations were used before and after application of a patellar realignment brace. No statistically significant differences were found in any of the three parameters for the patellofemoral relationships before or after wearing the patellar brace. The results indicated no stabilizing effect of the tested brace in patients with patellar subluxation or dislocation during active joint motion.