Application Of CT Perfusion Imaging Combined With CT Angiography In Ischemic Stroke

Part I:Exploring the CTP optimum values for dividing the infarct core and penumbra in ischemic stroke patientsPurpose:To explore the accuracy and the optimal parameter values of CT Perfusion (CTP) for detecting infarct core and ischemic penumbra in ischemic stroke patients by means of CTP original image post-processing, statistical analysis and receiver-operating characteristics (ROC) curve.Methods:From December2011to September2012, there were altogether58suspected ischemic stroke patients, and5were found no infarct core by MR-DWI while1was confirmed as TIA. So finally52ischemic stroke patients’clinical and imaging data from neurologic emergency Huashan hospital were collected. All patients accepted admission CT scan, CTP (baseline CTP) and CTA (baseline CTA) examinations. After24hours all patients would receive a second-time CTP (24-hour CTP) and CTA (24-hour CTA) for review and MR-DWI (24-hour DWI).CTA^CTP and MR images were processed by post-processing softwares. Taking the high signal region in24-hour DWI images for the golden standard, and compared with the mimical areas of infarct core and penumbra produced by different values of different parameters, statistical processing was done by SPSS20.0to find out the best parameters.Results:The optimum parameters to divide the infarct core and ischemic penumbra are relative cerebral blood volume (rCBV)≥60%and relative mean transit time (rMTT)≥150%, sensitivity and specificity respectively are (88%,74%) and (81%,78%).Conclusion:CTP can scan ischemic patients rapidly、safely with almost no contraindication and accurately show the extent of infarct core and penumbra, and it also can provide multi-parameter information of cerebral hemodynamics.Part II:Exploring the value of CTP and CTA examinations in the assessment of ischemic stroke patients’conditionPurpose:By analyzing the onset time and baseline NIHSS (National Institute of Health stroke scale) score with sizes of cerebral infarct core and penumbra and observing the result of detecting the large and medium-sized vessels by CTA to confirm the necessity of CTP and CTA examinations in ischemic patients.Methods:From December2011to September2012, there were altogether52ischemic stroke patients’clinical and imaging data from neurologic emergency Huashan hospital were collected. All patients accepted admission CT scan, CTP (baseline CTP) and CTA (baseline CTA) examinations. After24hours all patients would receive a second-time CTP (24-hour CTP) and CTA (24-hour CTA) for review and MR-DWI (24-hour DWI). CTA、CTP and MR images were processed by post-processing softwares. Taking the high signal region in24-hour DWI images for the golden standard, and compared with the mimical areas of infarct core and penumbra produced by different values of different parameters, statistical processing was done by SPSS20.0to find out the best parameters. Taking the best parameters as the default values and each patient’s baseline volumes of infarct core and penumbra are calculated by MIStar software. Correlation analysis of onset time and baseline NIHSS score with volumes of baseline infarct core and ischemic penumbra in ischemic stroke patients. Furthermore analyzing volumetric differences of baseline penumbra and infarct core among different time periods (within3hours,3-6hours,6hours or more) in different locations (basal ganglia, cerebral cortex, brainstem); Observation of the CT Angiography (CTA) abilities for detecting lumen status in large or medium arteries and suggesting possible etiology.Results:There is no obvious correlation between onset time and volume of baseline penumbra or infarct core in ischemic stroke patients;Baseline NIHSS score has weak correlation with the sum of the volumes of baseline penumbra and infarct core, but it is unable to distinguish the core and the penumbra;The average volume of baseline infarct core has no differences in different locations and time periods(within3hours、3-6hours、6hours or more), suggesting that in the case of severe ischemia, rate of neuron death is extremely high. The average volumes of baseline penumbra in cerebral cortex within3hours and6hours have statistical differences, indicating that compared with other parts, the cerebral cortex compensatory ability is stronger;CTA images with2D and3D reconstruction can clearly reflect the vascular information such as occlusive location、degree、plaque character and so on, which play an important role in finding the causes and grasping patients’conditions.Conclusion:Comparing to the onset time and baseline NIHSS score, CTP can more accurately show the cerebral hemodynamics in ischemic stroke patients. CTA can detect large and medium-sized vascular lesions and suggest possible causes.Part Ⅲ:Exploring the role of CTP and CTA examinations in the prediction of ischemic stroke patients’clinical outcomes after thrombolysisPurpose:Analyzing the relationship between results of CTP and CTA examination and effects of thrombolysis therapy to explore the value of CTP combined with CTA examination in estimating the clinical outcomes after thrombolysis in ischemic stroke patients.Methods:From December2011to September2012, there were altogether52ischemic stroke patients’clinical and imaging data from neurologic emergency Huashan hospital were collected. Physicians took patients’general condition、risk factors、laboratory test results、 imaging results and informed consent into account before making the thrombolysis decision or not, therapies:rt-PA0.9mg/Kg, maximum dose of90mg. All patients accepted admission CT scan, CTP (baseline CTP) and CTA (baseline CTA) examinations. After24hours all patients would receive a second-time CTP (24-hour CTP) and CTA (24-hour CTA) for review and MR-DWI (24-hour DWI).CTA、CTP and MR images were processed by post-processing softwares. Taking the high signal region in24-hour DWI images for the golden standard, and compared with the mimical areas of infarct core and penumbra produced by different values of different parameters, statistical processing was done by SPSS20.0to find out the best parameters. Taking the best parameters as the default values and each patient’s baseline volumes of infarct core and penumbra are calculated by MIStar software. Defining the blood mismatch as the specific value of baseline penumbra and baseline infarct core is larger than0.2, otherwise there is no mismatch; whether there is vascular occlusion is determined by two radiologists if they both confirm a existence of occlusion. Comparing different clinic outcomes(short-term outcome:24-hour NIHSS score change, long-term outcome:3-month mRS score) in following groups.(1)Receiving thrombolysis treatment or not in all patients.(2)CTA showing vascular occlusion or not in patients received thrombolysis treatment.(3)CTP showing hemodynamic mismatch or not in patients received thrombolysis treatment.(4)According to different CTA and CTP results (occlusion and mismatch、occlusion but no mismatch、mismatch but non-occlusion).Results:A total of29patients were treated with thrombolysis, and the short-term outcomes in patients received thrombolysis treatment is better than those without thrombolysis treatment. In predicting the effect of thrombolysis treatment, the short-term outcomes of patients with both vascular occlusion and CTP mismatch are the best,while the long-term outcomes have no significant correlation with baseline CTP and CTA examination results due to numerous influent factors.Conclusion:CTP combination CTA examination is helpful to predict short-term outcome after thrombolysis.