Dynamic Effects of Axial Loading on the Lumbar Spine During Magnetic Resonance Imaging in Patients with Suspected Spinal Stenosis

BackgroundPrevious studies have shown that axial compression in extension (ACE) of the spine during magnetic resonance imaging (MRI) has revealed unexpected pathological features compared with the conventional psoas-relaxed position (PRP) used in imaging. The purpose of this study was to evaluate the dynamic effect of axial loading on lumbar spinal stenosis using MRI in patients with spinal stenosis.MethodsA total of 14 women and 11 men with lumbar spinal stenosis were examined in both PRP and ACE positions. We calculated the dural-sac cross-sectional area (DCSA) to evaluate severity of spinal canal stenosis. DCSA, as well as the dural-sac anteroposterior diameter (DAPD) and dural-sac transverse diameter (DTD) in both positions were measured using a digital image view station. A paired t test determined the differences in DCSA, DAPD and DTD between the two positions at each intervertebral disc level.ResultsAxial loading increased severity of lumbar spinal stenosis during MRI, as demonstrated by a decrease in DCSA from 20.5% to 6.3% (mean, 11.40 ± 3.66%) between the PRP and ACE positions (p < 0.01). Significant differences were also noted in DAPD and DTD between the PRP and ACE positions (p < 0.01). A significant correlation was found between the decrease in mean DCSA and that in DAPD and DTD. The decrease in mean DCSA, DAPD and DTD following axial compression was greatest at the L4/5 and L5/S1 levels.ConclusionAxial loading increases severity of lumbar canal stenosis and the effect of axial loading on MRI examination is greatest at the L4/5 and L5/S1 levels

Combination of Tissue Harmonic Sonography, Real-Time Spatial Compound Sonography and Adaptive Image Processing Technique for the Detection of Carotid Plaques and Intima-Medial Thickness

Background and purpose: Conventional sonography (CS) had many unwanted artifacts, which obscured the carotid artery lesions. We try to explore whether the combination of tissue harmonic imaging (THI), real-time spatial compound sonography (SCS), and adaptive image processing (Alp) techniques (CTX) could be a better way to reduce the artifacts in the carotid artery and enhance the visualization of its plaques and intima- medial thickness ( IMT) than CS. Methods: Eighty-three patients who harbored IMT (73) and carotid plaques (19) with variable degrees of stenosis underwent scanning for which five different ultrasound techniques were performed for overall image quality, lesion conspicuity, and elimination of artifacts. Two observers, who were blinded to the imaging techniques, graded the different images. A Friedman test was used for multiple statistical comparisons between the five techniques . To make paired comparisons between different imaging modes , Wilcoxon's signed- rank test was used. Results: The mean Kappa score for the two independent observers was 0.812 ( standard error, 0.021), and reflected moderate-to- high interobserver agreement. Combining SCS + THI + All? (CTX) provided the best for overall image quality, lesion conspicuity, and elimination of undesired artifacts of carotid plaques whereas CS produced the worst quality (p < 0 .001). There were significant differences among the five techniques (p < 0.001); however, there were no differences between SCS and THI on either image quality (p = 0.417), lesion conspicuity (P = 0.594), or elimination of artifact ( p = 0.064). Conclusions: The combined technique of SCS, THI , and AIP may represent the optimal ultrasonic technique for the evaluation of the IMT and carotid plaque echomorphology