| ObjectivesTo evaluate diffusion-weighted imaging (DWI) in clinical and experimental studies and suggest it might be a new method of diagnosis in spinal cord diseases. Firstly, study the progressive features of DWI signals and the relative pathological changes of spinal cord ischemia models. Secondly, investigate the clinical cases in order to further clarify the DWI features of spinal cord infarction. Thirdly, observe cases of relative spinal cord diseases to assess the capacity of DWI in differential diagnosis.Methods1. Establish the msh-DWI method of human or canine spinal cord by a 1.5-Tesla MR system.2. Use embolizaiton agent with different matching of lipiodol and diatrizoate meglumine and different dosage, which are injected into bilateral intercostal arteries at T9-11 level guided by DSA monitor, to establish different spinal cord ischemia models of canine. MRI features and pathologic changes of spinal cord ischemia lesions are analyzed.3. Select medium-degree models of spinal cord ischemia to carry out MRI examination. Conventional MRI and DWI are performed continuously atone hour, two hours, six hours. 24 hours. 80 hours and seven days after the models are made. MR signal features of spinal cord ischemia are analyzed.4. Summarize DWI festures of human spinal cord infarction.5. Study relative clinical cases of spinal cord diseases, focusing on analyzing the DWI features.Results1. Msh-DWI methods of human and canine spinal cord are established successfully. Main parameters include: b value 500 s/mm"; TE 18 ms or shortest; thickness 5 mm. PPU or electrocardio-gating is necessary.2. Except one case, the other eight cases of embolization models are established in different degrees successfully. Among three groups, mild-group gets minor injury. The muscle power is about 3-5 grade and the range of injury is about two vertebrae distance; Medium-group presents obvious paraplegia. The muscle power is 0-1 grade and the range of injury is between 3-4 vertebrae distance; Severe-group shows greater severity and larger range of injury. The muscle power is 0 grade and the range of injury is over 4 vertebrae distance. All lesions present high signals on conventional MRI and DWI.3. Pathological changes of canine spinal cord infarction between three and seven days after models are established: HE staining shows hydropic degeneration, hyperemia and necrosis in spinal cord lesions. Glees-Marslcuel's staining reveals axis-cylinder swelling and disrupt. Electronic microscope shows mitochondria swelling, axis-cylinder of myelinated nerve fiber shrinking and separating from myelin sheath. Lamina structure of myelin sheath becomes derangement and fragmentation.4. All six embolization models of medium degree are established successfully. Diffusion-weighted images of all cases show signal changeswithin one hour after spinal cord infarction models are made; whereas only four cases present slight hyper-intensity on T2-weighted images. Six hours later. ADC values of infarction lesions diminish continuously, reaching the bottom at 24 hours, ft begins to increase gradually at 80 hours and seven days. In these infarction lesions. ADC values of transverse-diffusion and longitudinal-diffusion diminish. In three cases. DWI detects hemorrhage with low signal at 24 hours, which is obviously earlier than T|WI (at 80 hours). In addition, infarction vertebrae body and surrounding tissues also show according signal changes as well.5. Six patients (two male, four female) with typical sudden onset of neurological deficits caused by spinal cord ischemia are evaluated. Three cases occur in the thoracolumbar region and three others in the cervical cord. MR] is performed within 1-12 days after the initial neurological symptoms. MR abnormalities are demonstrated on sagittal T2-weighted images with "patch-like" or "strip-like" hyperintensities (6/6) and spinal cord enlargement (5/6). Axial T2-weighted images show bilateral (6/6) hyperintensities. Some lesions may show a typical sign of "snake eyes". In one case, only the posterior spinal artery territory is involved. Among three contrast-enhanced MRI cases, only one case shows irregular slight enhancement. ADC values of all infarction lesions range from 230xl0"6mm2/s to 470xl0"6 mm2/s (average value 360±100xl0"6mm2/s), which is markedly lower than the values of normal areas (average value 890±80xl0~6mm2/s). There are significant differences between lesions and normal regions (?=4.71, PO.01). All cases have better signal contrast in DW images than in T2W images. Two cases are followed up. ADC values of lesions increase gradually and get to almost normal value in three months.6. Relative diseases of spinal cord :(1) Twenty cases of acute spinal cord contusion. Two cases examined byssh-DWI show local lesions with significant high signals. Eighteen cases examined by msh-DWI are classified into three categories depending on different degrees of tissue injury and the characteristics of DWI: /. Edema-type: twelve cases present high DWI signals with different degree in local lesions. There are significant difference of ADC values between lesions and normal areas (7 = 4.783, /><0.01). //. Mixed-type: four cases show heterogeneous high DWI signals due to hemorrhage and edema in lesions. ///. Hemorrhage-type: two cases showed DWI low signals. (2) Twenty-eight cases of cervical spondylotic myelopathy. Sixteen out of 18 cases with TtWI hyper-signals show increased ADC values. In ten cases with negative T?WI. five present increased ADC values, which show DWI is more sensitive than conventional MRI. Three patients underwent surgical decompression treatment get follow-up examinations. They show different lowered ADC values than that before the operation. (3) Five cases of spinal cord inflammation. DWI of spinal cord inflammation lesions may present iso-intensity. slight hyper-intensity, or marked hyper-intensity signals. (4) Six cases of spinal canal tumors including meningioma, glioma, and teratoma. DWI describe meningioma as slight hyper-intensity, cystic component of glioma as low intensity, and cystic part of teratoma as hyper-intensity.Conclusions1. Msh-DWI of spinal cord can be performed successfully by 1.5 tesla MR system, which provides high quality images and can be used to measure ADC values.2. Guided by DSA monitor, embolizaiton agent with different matching of lipiodol and diatrizoate meglumine and different dosage are injected into bilateral intercostal arteries, which can establish different spinal cord ischemia models of canine. |
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