[Early diagnostic significance and dynamic pattern of DWI compared with conventional MRI in newborns with neonatal cerebral infarction].

OBJECTIVE: To evaluate the early diagnostic significance of diffusion weighted imaging (DWI) compared with conventional magnetic resonance imaging (MRI) and to find the dynamic pattern of DWI and conventional MRI in newborn infants with neonatal cerebral infarction (NCI).

METHODS: The imaging studies and clinical records of six newborn infants with NCI admitted to our ward between April 2004 and October 2005 were reviewed. All examinations were performed on a 3.0-T MRI system (Philips Intera Acheva Magnetom Vision) with echo-planar imaging capability with the use of a standard protocol. The imaging protocol for all the patients contained diffuse weighted images (EPI-SE, TR = 2144 ms, TE = 56 ms), T(1)-weighted images (TR = 389 ms; TE = 15 ms; slice thickness = 4 mm) as well as T(2)-weighted images (TR = 3035 ms; TE = 100 ms; slice thickness = 4 mm). Except the magnetic resonance image examination mentioned above, the following examinations were performed in all patients: whole blood cells count, serum total calcium and ionized calcium, blood glucose, C-reactive protein (CRP), blood culture, prothrombin time and partial thromboplastin time, chest radiograph (CR), cardiac color Doppler, conventional MRI and DWI of brain.

RESULTS: All the patients were full term infants. One had severe asphyxia and the other five had neither intrauterine distress nor birth asphyxia. Five of the patients had no localized neurological signs in the early course except for abnormal muscular tone to some extent, but just seizure as their major symptom. A seizure episode was the most common sign and no other positive signs of nervous system was found in the newborn with NCI. All the patients had normal white blood cells, red blood cells, blood platelet, blood glucose, serum total calcium and ionized calcium, prothrombin time and partial thromboplastin time, CRP and cardiac color Doppler. The first MRI was performed from 18 hours to 4 days after the onset of illness when four patients showed abnormal findings on routine MRI (T(1)WI hypointensity, T(2)WI hyperintensity) and the other two showed normal results while all the six showed abnormal hyperintensty on DMI. On following up, all the patients showed T(1)WI hypointensity and T(2)WI hyperintensity on routine MRI while hypointensity was shown on DWI. There were cortical and subcortical white matter damage with obvious high signal intensity on DWI in left temporal lobe and parietal-occipital lobes of 4 cases and in left frontal-parietal lobes of one patient and in left basal ganglia of another patient, but lesions of hypointensity on T(1)W and hyperintensity on T(2)W in only 3 patients between 2nd day and 3rd day after onset; two weeks later there were the lesions of hypointensity on T(1)W and on DWI and hyperintensity on T(2)W seen in all patients in the areas similar to those found before on DWI. Lesions of hypointensity on T(1)W and DWI and of hyperintensity on T(2)W remained in two patients at sixth month and in one patients at 15th month.

CONCLUSION: Seizure was the most common sign of newborn infants with NCI and seizures in the neonatal period may be the single symptom of acute ischemic cerebral infarction. It was difficult to establish the diagnosis in the acute phase by the use of ultrasound, CT, and conventional MRI because of the high water content of the immature brain.. DWI seems to be a sensitive early diagnostic measure for NCI. Hyperintensity was shown on DWI at the early stage of the disease. Two weeks later, the hyperintensity turned to hypointensity and lasted long with the same signal characters and lesions on T(1)WI. The lesions of hypointensity on T(1)W and DWI and hyperintensity on T(2)W appeared at 2 weeks and remained for more than 1 year. T(2)-weighted sequences should supplement DW images to reliably detect subacute ischemic infarctions in the neonatal period.