Purpose or Case Report: In neonates, ultrasound is the initial neuroimaging modality used to detect and follow intracranial pathologies, since MRI is challenging due to immobilization, costs and sedation issues. Ultrasound is typically acquired in 2D and interpretations are performed slice by slice. However, recent reports suggest a longitudinal follow-up of structure volumes and shapes may be relevant for investigation of neurodevelopmental disorders. The objective of this study is to test the diagnostic efficiency of the 3D ultrasound technology to measure total brain volume as well as lateral ventricular volume compared to volumetric measurements obtained from MRI.
Methods & Materials: In this prospective study, 12 infants ranging between 2mo to 8.5mo were recruited (normal condition except one with hydrocephaly). For each patients, T1 MRI images were acquired on a 3T MR 750 GE scanner. Following the MRI, infants were transferred to the wake-up room and underwent a 3D volume US acquisition performed in the coronal plane using the EPIQ7 system with the X6-1 matrix array transducer (Philips), acquired through the anterior fontanel. To estimate total brain volume on US, a geometric-based method was developed, which uses 3D ellipses that are well fitted to the bone edges of the skull. All MRI scans were processed to extract total brain sizes and structure volumes. Lateral ventricles volumes were manually segmented and validated by an experienced radiologist on both MRI and ultrasound (Fig 1).
Results: Figure 2 depicts the volumes of the left and right ventricles for each subject, as well as for total brain volumes. There was a near perfect correlation between individual ventricle volumes obtained with 3D US and those with MRI (r=0.999). Based on paired student t-test and F-Test, there was no statistically significant difference (T: p = 0.204) (F: p=0,429) between both distributions. For the total brain size, the correlation between both modalities was r=0,988, and no statistically significant difference (T: p = 0.309) (F: p=0,477) was found between both distributions. Figure 3 shows the evolution of ventricle volumes with respect to the age of the patient.
Conclusions: This study establishes the feasibility of performing volumetric ultrasound of the ventricles and the head volume for assessment of macrocephaly, opening a wide range of opportunities for radiologists to evaluate childhood brain development, and its implication in certain neurological and neurosurgical conditions using non-invasive portable imaging modalities.