Artemis123 Whole Head Neonatal Biomagnetometer

A new, noninvasive investigational tool for pre- and full-term infants

Mapping brain function and detecting neurological abnormalities in infants

Detection of cortical function in newborns is needed for clinical intervention in the early stages of neurological disorders, before external signs appear and the conditions develop and worsen. Potential uses of Artemis123®1 for neonatal neurological assessment include:

• Autism
• Epilepsy
• Cerebral palsy
• Perinatal asphyxia
• Hypoxemic-ischemic encephalopathy
• Periventricular white matter injury
• Monitoring recovery from trauma

Identifying how infants learn is of interest to many sectors of society, but such studies rely heavily on behavioral analyses. Having a direct measure of cortical activity would provide precise information on the dynamic response in the brain during learning processes.

1 Artemis123® is a registered trademark of Tristan Technologies, Inc. All rights reserved

Artemis123® System Description

Principles of Operation

Like adult Magnetoencephalography (MEG) systems, Artemis123® uses superconducting sensors to non-invasively detect and map magnetic fields generated by cortical neural activity. However, Artemis123® takes advantage of the fact that the infant’s scalp and skull are very thin. Tristan’s fabrication methods put the sensing coils very close to the infant brain’s sources of activity, even though SQUIDs must operate in an ultra-cold liquid helium environment. The net result is a significant increase in amplitude of neonate MEG signals. Also, the high density of detectors results in higher spatial resolution compared to adult whole-head MEG.

System Components

Sensor/Cradle/Bed on mobile cart – easily accessed height

Power supplies and computer on companion mobile cart to minimize noise

Subject Tracking – optical tracking system updates movement at 30 Hz with ½ mm accuracy

Part-wise mapping or optional optical one-click 3D imaging system

Mapping of sites and dynamics of sensory functions – auditory, somatosensory, and visual modalities

Assay stages of nervous system development

Somatic evoked magnetic field (SEF) obtained from a 7-month old as a function of number of averages from N=4 to 173 epochs. The waveforms are the differences of the SEF at two field extrema. This shows that a small number of averages are needed to acquire SEF data. (data acquired using a Tristan babySQUID® system).

Unique Features of Artemis123®

Superior spatial resolution and sensitivity

Significantly more sensitive to neuronal sources than conventional whole-head MEG systems

Similar or better spatial resolution compared to existing whole-head MEG sensors

Better spatial resolution than EEG (EEG signals are distorted by skull defects (fontanels and sutures), making it difficult localize epileptiform tissue

Rapid scanning: a typical clinical scan can be completed within thirty minutes

Anti-vibration construction; infant motion will not cause vibrational artifacts

Sensor noise level < 10 fT/ Hz

A dense array of closely-spaced sensors located just below the outer surface of a headrest.

Allows simultaneous measurement of the occipital area and parietal and temporal areas

Includes position tracking device and software, permitting measurements during sleep or relatively quiescent wakefulness

The measurement cradle and companion electronics cart are portable and can be wheeled in and out of elevators, obstetric suites and neonate ICUs

SQUID Sensor Array

606 cm2 sensor coverage area 100+ detection coils

Coil type: 15 mm-diameter first order gradiometers. Adjacent coils can be electronically combined to form planar gradiometers

Coil gap: ~8 mm from sensor to outer surface Coil sensitivity: better than 10 fT/ Hz

Reference channels: 6-element reference array for noise reduction

BabySQUID® Patient Data

Left Hemisphere Right Hemisphere

Contralateral

Ipsilateral

A 9-year old with cerebral palsy (unilateral congenital malformation in the left hemisphere in the lower somatosensory and motor cortices). Left: MRI image of the malformation. Right: Somatosensory evoked magnetic field (SEF) produced by tactile stimulation to the tip of left and right index fingers. Note a strong SEF in the intact right cortex after left index finger stimulation, and abnormal small initial cortical response and ipsilateral response in the affected left hemisphere after the right index stimulation.

Power and Physical Requirements

Power: 1.5 kW filtered circuit

Patient bed: 1 m x 2 m x 1.1m (40″ x 79″ x 42″) Patient bed weight: 200 kg (440 lbs)
Instrument cart weight: 150 kg (330 lbs)

Larger coverage areas, higher channel counts, and/or different coil dimensions and configurations are available on request. Contact Tristan for additional information.

All Tristan products are covered by a 1-year warranty. Service contracts may be purchased to provide post-warranty coverage.