The Application Of Mri In Term Newborns With Perinatal Arterial Ischemic Stroke

Part I Conventional MRI, Diffusion weighted imaging and ADC value in normal term neonatal brainObjective:To investigate the appearance of normal neonatal brain on conventional MRI and diffusion weighted imaging and the diversity of ADC values in various brain regions, establish normal parameters for the follow-up study. Materials and Methods: 9 term neonates without abnormal obstetric history during pregnancy were examined with a 1.5T MR imaging system(Avanto; Siemens, Erlangen, Germany). Their perinatal medical records and nervous system examinations were nothing remarkable. All of 9 neonates were performed with conventional MRI and DWI, and there was no abnormal signal-intensity on conventional MRI and diffusion weighted imaging. The routine MR imaging protocol include transverse T1-weighted, transverse T2-weighted, transverse diffusion-weighted imaging. ADC values in bilateral cerebellar cortex(CC), posterior limb of internal capsule(PLIC), cerebral peduncle(CP), splenium of corpus callosum(Splenium), lentiform nucleus (LN), ventrolateral nuclei of the thalamus(VLN), occipital cortex(OC), occipital white matter(OWM), parietal cortex(PC), parietal white matter(PWM), frontal cortex(FC) and frontal white matter(FWM) were analyzed. Results:All of 9 neonates were successfully performed with conventional MRI sequences and DWI. The appearance of neonatal brain on MRI is different from adults, since the immaturity of neonatal brain with high content of moisture. ADC values in the same region of interest(ROI) had no statistic difference between left and right hemisphere(P>0.05). ADC values of superficial white matter were significantly higher than deep white matter, deep nuclear, and superficial grey matter (P<0.05). In deep white matter, deep nuclear, and cortex, ADC value of different regions was with no difference between each other except for CP and FC, CP and PC, and VLN and PC(P<0.05). In superficial white matter, ADC value of OWM was lower than FWM and PWM(P<0.05). Conclusion:ADC values in the same brain regions of normal term newborns have no statistic difference between left and right hemisphere. ADC values in various brain regions is different, it reflects the myelination time and the features of myelin sheath.Part Ⅱ The application of MRI in term newborns with perinatal arterial ischemic strokeObjective:To discuss the role of conventional MRI, diffusion weighted imaging and magnetic resonance angiography in term newborns with perinatal arterial ischemic stroke. To investgate the difference of ADC values in various regions between stroke brain and control group by quantitative analysing of ADC values. Materials andMethods:21 term neonates diagnosed with PAIS, including 12 males and 9 females, birth weight 3 383±422 g.5 cases of emergency cesarean delivery,15 cases presented with seizure, admission time was 3 h to 5 d after birth. All MRI examinations were performed within 7 days after birth including routine MRI and DWI. And 9 cases performed magnetic resonance angiography (MRA) scan. ADC values of different regions of affected side and the other side including VLN, LN, CC, FC, CP, PLIC, Splenium, PC, PWM, lesions, symmetrical region on the other hemisphere, a total of 18 ROIs were analyzed with the control group. Different MCA infarction types were analyzed. Results:In the first series of conventional MRI images, there were hypointensity in T1WI in the affected areas (7 cases), subtle hypointensity (11 cases); there were hyperintensity in T2WI in the affected areas (14 cases), subtle hyperintensity (5 cases) and with poor differentiation between grey and white matter. First series of DWI images showed distinct hyperintensity in 21 cases in affected areas, the edge of the lesions were clearer than routine MRI. In addition, DWI found more lesions than routine MRI including the genu and splenium of corpus callosum, thalamus, posterior limb of internal capsule and cerebral peduncle.19 patients’MCA territory was involved.9 patients had MRA examination.6 patients presented with cortical branches increased in the affected areas. Compared with superficial type, mixed infarction had a strong relationship with the involving of CP, VLN, and with a higher incidence of PLIC, CP corpus callosum(CC) involved. ADC values of PLIC, CP, VLN in affected side were significantly lower than the other side(P<0.05), and the affected areas was the most significantly decreased region(P< 0.01). There was no statistic difference between regions of health side and control group(P>0.05). Compared with superficial group, ADC values of PLIC, LN and VLN in the affected hemisphere of mixed group were lower (P=0.0246,0.0268, 0.0153), and the rest were with no difference(P>0.05). Conclusion:Compared with conventional MRI, DWI can diagnosis PAIS earlier and find small lesions in the deep brain. The combined use of conventional MRI and DWI can detect the occurring time of the disease. The early MRA mostly show the cortical branches increased in the affected areas, which is different from arteriostenosis or occlusion in adults. ADC values of PLIC, CP, VLN in affected side were significantly lower than health side(vulnerable to affcet), and the affected areas was the most significantly decreased region. ADC values of other areas were similar to that of control group.