Sonography of neonatal periventricular leukomalacia: recent experience with a 7.5-MHz scanner.

This study compared the relative efficacy of 5.0- and 7.5-MHz (high-resolution) transducers in the sonographic evaluation of cystic periventricular leukomalacia (PVL). Of 668 premature neonates evaluated by cranial sonography over a 4-year period, 34 were diagnosed as having PVL. Of these 34 neonates, 17 were examined with both 5.0- and 7.5-MHz transducers. Fifty-two neonates with no evidence of PVL also were evaluated by sonography with the two different-frequency transducers to determine the normal appearance of the neonatal brain. Among the neonates with PVL, features of the disease that have not been observed with routine 5.0-MHz transducers were apparent with use of the 7.5-MHz transducer: 7.5-MHz scanning clearly identified small areas of cystic PVL in three (17.6%) of 17 neonates that were not visible using the lower-resolution technique. The higher-resolution scanning also identified widening of the interhemispheric fissure by anechoic cerebrospinal fluid and demonstrated the falx as a distinct structure. The latter two superficial abnormalities were identified in combination with enlargement of the lateral and third ventricles, suggesting that diffuse cerebral atrophy accompanies PVL in most cases. The excellent near-field resolution of 7.5-MHz technology makes it the preferred method for the evaluation of PVL in the preterm neonate.