MR line-scan diffusion-weighted imaging of term neonates with perinatal brain ischemia

BACKGROUND AND PURPOSE: MR diffusion-weighted imaging provides early demons tration of neonatal brain infarction, The evolution and limitations of diff usion-weighted imaging findings in newborns, however, have not been evaluat ed, Using line-scan diffusion imaging (LSDI), we investigated perinatal isc hemic brain injury. METHODS: Nineteen term newborns (age, 9 hours to 8 days; mean age, 2.6 days ) with perinatal brain ischemia were evaluated using LSDI (1520/62.5/1 [TR/ TE/excitations]) (b maximum = 750 s/mm(2)) and T1- and T2-weighted spin-ech o (conventional) MR imaging. Follow-up examinations were performed in seven patients and autopsy in one. Apparent diffusion coefficients (ADCs) were m easured in deep gray matter, white matter, the cortex, and focal lesions. RESULTS: Based on conventional MR imaging or pathologic findings, patients were divided into two groups. Group 1 (n = 12) had symmetric/diffuse injury consistent with global hypoperfusion. Group 2 (n = 7) had focal/multifocal injury suggesting cerebrovascular occlusion, ADCs were abnormal at initial examination in 10 newborns in group 1 and in all newborns in group 2, The results of LSDI were abnormal before conventional MR imaging was performed in three newborns in group 1, ADCs were maximally decreased between days 1 and 3 in deep gray matter, perirolandic white matter, and focal lesions, De layed decreases in ADCs were observed in subcortical white matter from days 4 through 10 in three patients in group 1, CONCLUSION: After global hypoperfusion, LSDI showed deep gray matter and pe rirolandic white matter lesions before conventional MR imaging. LSDI may un derestimate the extent of injury, however, possibly because of variations i n the compartmentalization of edema, selective vulnerability, and delayed c ell death, Differences in LSDI of symmetric/diffuse and focal/multifocal le sions may reflect differences in pathophysiology or timing of the injury, T hese findings may have implications for acute interventions.