Study On ESWAN Parameter Settings Optimization And Imaging Of Hemorrhagic Cerebral Infarction

PART Ⅰ COMPARISON OF ESWAN PERFORMANCESWITH DIFFERENT PARAMETERS OF PARAMAGNETICMATERIAL AT3TObjective: To study the influences of the enhanced gradient echo T2*weighted angiography （ESWAN） sequence parameter settings on thecharacteristics of imaging and the sensitivity of paramagnetic ion withexperimental methods in vitro to do optimization on the ESWAN parametersettings.Methods: To establish a model of paramagnetic material, to change thenumbers of echo time, flip angle （FA）, bandwidth （BW）, field of view （FOV）on the ESWAN sequence and repeat scanning. The signal changes wereobserved and the phase values of the interesting area in different positions atall images were measured. The relationship between the ESWAN imagingquality and the different parameters was analyzed.Results: The ESWAN signal of Fe²⁺was slightly high, the phase value increased with the concentration when it was low, while the phase valuedecreased with the increased artifacts. The phase values’ changes were lackof specificity with different number of echo time, FA, BW, and FOV. Thecontrast to noise ratio （CNR） was greater when the number of echo time wassmaller since the concentration was increased （P<0.05）, the CNR differencebetween different flip angles was not statistically significant （P>0.05）, theCNR value was greater when bandwidth was wider （P<0.05）, the CNRdifference between different FOVs was not statistically significant （P>0.05）.Conclusion: The CNR was different with choosing differentparameters according to different concentrations. The ESWAN features varywith different parameters. Reasonable parameter settings play an importantrole in showing paramagnetic substances with ESWAN sensitively andeffectively. PARTⅡ STUDY ON IMAGING OF CEREBRALINFARCTION WITH CEREBRAL MICROBLEEDSObjective: To investigate the value of ESWAN performance in cerebralinfarction with cerebral microbleeds （CMBs）. Methods:55patients from March to October in2011in our hospitalwith MRI diagnosis of cerebral infarction were collected with axial T₁fuid-attenuated inversion recovery imaging （FLAIR）, T₂WI, T₂FLAIR,diffusion-weighted imaging （DWI） and ESWAN sequences performed. Thesites, numbers, characteristics of CMBs were recorded. The value of earlydetection of microbleeds by ESWAN was analyzed.Results: CMBs were detected in29cases （52.73%） on ESWAN, whichwere detected in16cases （29.09%） on conventional MR sequences （χ²=6.36,P<0.05）, and in3cases of34patients who took CT scan （8.82%）（χ²=29.79,P<0.01）. Among the29cases, CMBs in15patients （51.72%） represented assmall round signal loss, which located only outside of the infarct lesions,CMBs in11patients （37.93%） represented as small sheet, strip signal lost,only in the infarct lesions, and CMBs in3patients （10.34%） were both inand outside of the infarct lesions.11cases （37.93%） were lacunar infarctionpatients in the29cases,9cases （81.82%） of which were outside CMBs.14cases （48.28%） were large infarction patients in the29cases,10cases（71.43%） of which were inside CMBs. The difference between teamsof these cerebral infarction stages was statistically significant （P<0.05）.Presence of CMBs with encephalomalacia focus occurred more easily（P<0.05）.Conclusion: CMBs were closely related to the degree of vascularinjury and ESWAN can help confirm the diagnosis of cerebral infarction with microbleeds.