| 1. BackgroundThe diseases caused by degenerative changes of lumbar intervertebral discs were very common in clinic.Among them,nucleus pulposus behaved more significantly than annular fibrosus and cartilage enderplate.Its main appearances included the change of chondroitin sulfate and keratin sulfate components,and the decrease of water content. Sequentially the biomechanics properties of nucleus pulposus altered,and caused a series of clinical symptoms.So the exact evaluation of degeneration grade was of great importance in clinical diagnosis and treatment and prognosis. At present,the signal intensity of nucleus pulposus in MRI was always used as the index to evaluate the degeneration grade.But the pathological basis of degeneration was the change of chondroitin sulfate and keratin sulfate components.Unfortunately,up-to-date,there were no concerned research focused on the relationship between signal intensity and pathological changes.2. ObjectiveOur study was designed to observe and quantify the pathological changes of nucleus pulposus in lumbar intervertebral discs,and compare them with the appearances in MRI, and then analyze their correlations,so as to provide a relative credible proof for evaluating the nucleus pulposus degeneration of lumbar disc by MRI in clinical course.3.Materials and methods3.1Clinical datumFrom 2001.1 to 2001.12,cases with operation of lumbar disc disease were selected as case group and then divided into three groups according to their age:young group,aging from 21 to 30,\vith an average of 26.9,including 7 male cases(7 discs) and 2 female ones(3discs);middle group,aging from31 to50,with an average of 43.7,including 33 male cases(35 discs) and 28 female ones(23 discs);old group, aging from51 to70,with an average of 59.9,including 11 male cases(12 discs) and 11 female ones(lldiscs).On the other hand,4 cases(6 discs)of lumbar fracture patients(without previous low back pain) and 2 cases (10 discs)of fresh brain-injury cadaver (less than 2 hours after death) were selected as control group,aging from 20-30,with an average of 26.1,including 4 male cases(14 discs) and 2 female ones(2 discs).There were all 117 discs,including 7 LI-2 ones,9 L2-3 ones,5 L3-4ones,49 L4-5 ones and 47 L5S1 ones. 3.2 Preparation of specimensThere were no macroscopic disc diseases in control group.Typical nucleus pulposus tissues were obtained through operation. A 0.5x0.5><0.5cm bit was selected and fixed with 10% formalin solution,and then embedded into paraffin wax.Other tissues were measured wet weight ,and then measured dry weight after 24 hours' dehydration. Then water content was calculated.t? /'* ? # jjjg ? ^ & j? jt<sub><sub><sub><sub><sub>3.3 Alcian blue critical electrocyte concentration (CEC) stainingAll waxes were sliced with a thickness of 4 u m.There were 4 sections in every specimen,one was stained with HE,and others were stained with 0.05% Alcian blue acetate buffer(PH 5.8) in 0.05% or 0.45% or 0.9% magnesium chloride solution respectively.The staining time was kept consistent.After staining,all sections were photographed with Olympus camera,and films were treated with photoshop 6.0 software. The dyed color was classified into 5 grades,from ?to +++,and compared among three sections of one specimen.Ten 5 mm* 5mm areas wiih the same coordinate location in three pictures were selected as a group and their color grades were observed. When the color grade altered,the concentration of magnesium chloride were recorded .This concentration was just the CEC value of that area.The frequency of CEC value of every specimen was calculated. All the dyed results were read by two independent experts.3.4 Measurement of the relative signal intensity(RSI) and relative disc height(RDH) in MRIBefore operation ,all cases were examined with MRI,with a 0.5Tes/a magnetic field .In sagital films of T2WI(TR/TE=4000/112),gray values of nucleus pulposus and adjacent cerebrospinal fluid (CSF)were measured and then RSI calculated.RSI= (SlaXNa+SIbXNb) /(Na+Nb)/SIcs... |
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