Dynamic Magnetic Resonance Imaging Evaluation of Craniovertebral Junction Abnormalities
ABSTRACT To evaluate the role of dynamic magnetic resonance imaging (MRI) in craniovertebral junction (CVJ) abnormalities.
Twenty-five patients with suspected CVJ abnormalities underwent dynamic MRI of the CVJ, and in 20 of these patients, noncontrast computed tomography scan of the CVJ was done. The images were evaluated for atlantoaxial instability (AAI), spinal canal narrowing, cord compression, presence of altered cord signal intensity, and bony abnormalities in neutral, flexion, and extension.
Dynamic MRI detected 15 cases of AAI (10 fixed and 5 mobile AAI), 21 patients had varying degrees of spinal canal narrowing. Five patients showed increased narrowing on flexion/extension. Two patients demonstrated direct cord compression in flexion, whereas in neutral position, only dural compression was seen. One patient had cord compression on extension that was not seen in neutral or flexed position.
Dynamic MRI was able to detect cases of cord compression that were not seen in neutral position and was diagnostic in all cases of mobile AAI where mobility at this joint affects the treatment options. Dynamic MRI is extremely useful for evaluating craniovertebral junction abnormalities and, in particular, cord compression.
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ABSTRACT: The multitude of symptoms following a whiplash injury has given rise to much discussion because of the lack of objective radiological findings. The ligaments that stabilize the upper cervical spine can be injured. Dynamic kine magnetic resonance imaging (dMRI) may reveal the pathological motion patterns caused by injury to these ligaments. To compare the findings and motion patterns in the upper cervical spine, 25 whiplash trauma patients with longstanding pain, limb symptoms and loss of balance indicating a problem at the level of C0-C2, as well as matched healthy controls were imaged using dMRI. Imaging was performed with an Intera 1.5 T (Philips Healthcare, USA) magnet. A physiotherapist performed the bending and rotation of the upper cervical spine for the subjects to ensure that the movements were limited to the C0-C2 level. An oblique coronal T2- and proton density-weighted sequence and a balanced fast field echo axial sequence were used. The movements between C0-C2 and the signal from the alar ligaments were analyzed. Contact of the transverse ligament and the medulla in rotation was seen in two patients. The signal from the alar ligaments was abnormal in 92% of the patients and in 24% of the control subjects (P<0.0001). Abnormal movements at the level of C1-C2 were more common in patients than in controls (56% versus 20%, P=0.028). Whiplash patients with longstanding symptoms had both more abnormal signals from the alar ligaments and more abnormal movements on dMRI at the C0-C2 level than controls.Pain research & management: the journal of the Canadian Pain Society = journal de la societe canadienne pour le traitement de la douleur 14(6):427-32. · 1.52 Impact Factor
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ABSTRACT: Magnetic Resonance Imaging (MRI) has become an important tool for dynamic clinical studies. Regrettably, the long acquisition time is still a challenge in dynamic MRI. Several undersampled reconstruction techniques have been developed to speed up the acquisition without significantly compromising image quality. Most of these methods are based on modeling the pixel intensity changes. Recently, we introduced a new approach based on the motion estimation of each object element (obel, a piece of tissue). Although the method works well, the outcome is a trade off between the maximum undersampling factor and the motion estimation accuracy. In this work we propose to improve its performance through the use of additional data from multiple coils acquisition. Preliminary results on cardiac MRI show that further undersampling and/or improved reconstruction accuracy is achieved using this technique. Furthermore, an approximation of the vector field of motion is obtained. This method is appropriate for sequences where the obels’ intensity through time is nearly constant.12/2007: pages 522-532;
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ABSTRACT: Kinetic MRIs of cervical spines were obtained and analyzed according to the amount of motion and the degenerative grade of the intervertebral disc. To define the relationship between the grade of disc degeneration and the motion unit of the cervical spine and elucidate changes in the role of each cervical spine unit during flexion-extension motion caused by degeneration. Degenerative changes in the cervical disc occur with age. The correlation between the degree of cervical disc degeneration and extent of cervical spine mobility has not yet been determined. The effect of degeneration on the overall motion of the functional spinal unit also remains undefined. We studied 164 patients with symptomatic neck pain. The cervical intervertebral discs were graded by spine surgeons according to the degenerative grading system (Grades I to V). All radiologic data from kinetic MRIs were recorded on a computer for subsequent measurements. All measurements and calculations for translational motion and angular variation of each segment were automatically performed by a computer analyzer. The translational motion in discs with Grade II degeneration (mild degeneration) increased to Grade III degeneration (higher degeneration). However, the translational motion and angular variation significantly decreased for the Grade V (severe degeneration). For patients with relatively low grades of degeneration, Grades I and II discs, the C4-C5 and C5-C6 segmental units contributed the majority of total angular mobility of the spine. However, for the severely degenerated segments, Grade V discs, the contributions of the C4-C5 and C5-C6 U significantly decreased. The changes that occur with disc degeneration progress from the normal state to an unstable phase with higher mobility and subsequently to an ankylosed stage. This study evaluated the contribution of different levels to the changes in overall motion that occur with degeneration.Spine 02/2008; 33(2):187-93. DOI:10.1097/BRS.0b013e3181604501 · 2.30 Impact Factor