Intracranial pressure correlates with brain stiffness measured by noninvasive ultrasound-based transcranial time-harmonic elastography in children and young adults.

Purpose: Elevated intracranial pressure (ICP) accompanies many neurological disorders, and delayed diagnosis can cause irreversible brain damage. Current diagnostic testing is invasive. Ultrasound elastography allows non-invasive assessment of tissue stiffness, which is influenced by pressure. Transcranial time-harmonic elastography (THE), using externally induced low-frequency vibrations and standard ultrasound to generate quantitative stiffness maps, has proven sensitive to ICP changes in adults. This study evaluated the quantitative correlation between ICP and brain stiffness in children and adolescents using a novel point-of-care THE system with a portable vibration unit. Materials and Methods: Ten pediatric and one young adult patient (four females; mean age 11±5 years; range 6-24 years) with an implanted sensor reservoir (n=7) or external ventricular drainage (EVD; n=4) underwent transcranial THE with a portable vibration driver providing external multifrequency vibration. Quantitative shear-wave speed maps (m/s) of the temporal lobe were acquired. ICP was measured via sensor reservoir within two hours of THE or via EVD simultaneously. Three patients with sensor reservoirs were examined repeatedly at intervals of at least one month, yielding 16 ICP-THE pairs. Results: The median ICP was 8mmHg (range 2-13) and the median shear-wave speed was 1.54m/s (range 1.20-1.94). ICP correlated positively with brain stiffness measured by THE (r=0.72, p<0.05). Conclusion: Cerebral stiffness quantified by transcranial THE closely reflects invasively measured ICP. Therefore, portable, point-of-care THE may provide a cost-effective, non-invasive tool to monitor cerebral stiffness and detect increased ICP.