Comparing brain white matter on sequential cranial ultrasound and MRI in very preterm infants

Abstract

Introduction Periventricular white matter (WM) echodensities, frequently seen in preterm infants, can be associated with suboptimal neurodevelopment. Major WM injury is well detected on cranial ultrasound (cUS). cUS seems less sensitive for diffuse or more subtle WM injury. Our aim was to assess the value of cUS and magnetic resonance imaging (MRI) for evaluating WM changes and the predictive value of cUS and/or MRI findings for neurodevelopmental outcome in very preterm infants with normal to severely abnormal WM on sequential high-quality cUS. Materials and methods Very preterm infants (<32 weeks) who had sequential cUS and one MRI within the first three postnatal months were included. Periventricular WM on cUS and MRI was compared and correlated with neurodevelopmental outcome at 2 years corrected age. Results Forty preterm infants were studied; outcome data were available in 32. WM changes on sequential cUS were predictive of WM changes on MRI. Severely abnormal WM on cUS/MRI was predictive of adverse outcome, and normal-mildly abnormal WM of favorable outcome. Moderately abnormal WM on cUS/MRI was associated with variable outcome. Additional MRI slightly increased the predictive value of cUS in severe WM changes.

Interobserver variability in assessment of cranial ultrasound in very preterm infants

“…showing that infants with normal cUS at term age had normal MRI or only mildly WM abnormalities [8], consistent with the study by Leijser et al [6,7]. A study comparing cUS and MRI showed that inhomogeneous grade I WM echogenicities seen on cUS seem to correlate with subtle white matter abnormalities such as punctuate WM lesions on MRI [9] These two studies have been performed in centres of high expertise in cUS ultrasound performance and interpretation.…”

“…Depending on the local settings and the interaction between the neonatologist and radiologist the level of expertise may vary significantly. Poor kappa values in this study suggest that cUS performance and interpretation should be improved by structured and continuous training as other units have shown that cUS well done is effective at detecting abnormality and normality and predicting outcome [5,6,19].…”

“…Recent studies compared sequential cUS and single cUS at term equivalent age respectively with Magnetic Resonance Imaging (MRI) at term equivalent age [5][6][7]. Comparison of sequential cUS and conventional MRI at term equivalent age and their relation to neurodevelopmental outcome revealed predictive values of normal to mildly abnormal white matter (WM) on cUS for normal to mildly abnormal WM on MRI a sensitivity of 0.92, specificity of 0.86, positive predictive value (PPV) of 0.92 and a negative predictive value (NPV) of 0.86 [6,7]. Hence, cUS seems a reliable tool for detecting major forms of WM injury including cPVL and parenchymal infarction, but a poorer predictor of diffuse or more subtle WM lesions [7].…”

The rationale for routine cerebral ultrasound in premature infants

“…Studies using this protocol [21,22] have demonstrated a higher sensitivity in predicting outcomes than those applying brain US on a less frequent basis [23,24]. Serial US will not miss: (1) periventricular cysts of focal periventricular leukomalacia (PVL), which appear after the first postnatal week, progressively coalesce and then disappear at about term-equivalent age by forming the wall of the lateral ventricles [4,11]; (2) periventricular clastic lesions secondary to sepsis, necrotizing enterocolitis and viral and fungal infections developing any time in the neonatal period [11,[14][15][16]25]; (3) post-haemorrhagic ventricular dilatation that may develop any time after intraventricular hemorrhage [26], and (4) perforator stroke occurring any time after the first week and sometimes affecting the posterior limb of the internal capsule [12].…”

Ultrasound screening in a neonatal unit

“…Periventricular flaring in infants of less than 32 weeks gestation may present ischemic and/or inflammatory damage. 5 When persisting for over one week, and when the echogenicity exceeds that of choroid plexus, flares are considered the first stage of periventricular leukomalacia. 5 MRI is the examination of choice for suspected HIE.…”