Acoustocerebrography

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The Akustocerebrografie ( ACG ) is a diagnostic tool in medicine, primarily for the diagnosis of diseases of the brain and central nervous system functions. It can also be used for continuous brain and intracranial pressure monitoring . The ACG is a non-invasive, transcranial acoustic spectroscopy based on molecular acoustics and allows the investigation of the cell and molecular structure of the brain. It works without side effects without the use of ionizing radiation. The ACG also enables the assessment of blood flow and cerebral circulatory disorders.

Passive and active acoustocerebrography

Passive acoustocerebrography

The flow of blood through the vascular system of the brain exerts force on the surrounding tissue and creates its movement. Each heartbeat causes the brain to vibrate in the skull according to a repetitive pattern. This vibration is dependent on the size, shape, structure and blood flow in the vascular system of the brain. The oscillating movement moves the brain tissue and the spinal fluid and exerts minimal pressure on the skull (changes in intracranial pressure). The effect of these vibrations on the skull can in turn be recorded and measured. In order to detect these signals on the scalp, passive sensors such as accelerometers are currently used, and sometimes highly sensitive microphones are used for the purpose of recording signals. Thanks to the digitization of the sensor signals, it is possible to measure the movement patterns of the skull. The brain signal properties (the signatures) are examined with special algorithms and identified as normal or as patterns with various abnormal courses.

Active acoustocerebrography

The active ACG uses a multi-frequency ultrasound signal to detect and classify undesirable cellular or molecular changes in brain tissue. In addition to the advantages of the passive ACG, the active ACG also enables a spectrum analysis of the acoustic signals. With such spectral analyzes, not only the changes in the vascular system of the brain, but also in its cell and molecular structure can be assessed.

A variant of the active ACG is the TCD examination (from English Transcranial Doppler). Transcranial Doppler and its newer version, the transcranial color Doppler (TCCD), are ultrasound measuring methods that enable the speed of blood flow through the blood vessels of the brain to be measured. They are used to diagnose embolism , stenosis, or vasoconstriction due to e.g. B. to support subarachnoid hemorrhage (bleeding from the aneurysm ).

Fields of application of acoustocerebrography

In contrast to results from snapshots such as MRT and CT , the ACG enables continuous real-time monitoring of the patient with little effort, especially in the time-critical acute phase after a stroke or traumatic brain injury . The measurement data are evaluated using statistical and mathematical methods and displayed on a monitor. The computer-aided analysis of the signals enables the doctor or medical nursing staff to clearly interpret the results immediately after using the device. The ACG also enables a preventive diagnosis of pathophysiological changes in brain tissue.

Individual evidence

  1. ^ Bogdan et al .: Computer Aided Multispectral Ultrasound Diagnostics Brain Health Monitoring System based on Acoustocerebrography . (PDF) 2015
  2. ↑ Werner Schaaffs: Molecular acoustics - An introduction to the relationships between ultrasound and molecular structure in liquids and gases . 1963, DNB 454290918
  3. ↑ Smith et al .: Cranial Accelerometry Can Detect Cerebral Vasospasm Caused by Subarachnoid Hemorrhage . 2015
  4. ↑ M. Sun, LN Sekhar, RJ Sclabassi, JF Wasserman, HB Blue, KA Luyckx: Recording and processing aneurysmal vibration signals in dogs. In: Journal of biomedical engineering. Volume 10, Number 4, July 1988, pp. 336-342, PMID 3070164 .
  5. ↑ Sekhar et al .: Acoustic recordings from experimental saccular aneurysms in dogs . 1990
  6. ↑ Kosugi et al .: Detection and Analysis of Cranial Bruit . 1987
  7. ^ RP Dutton, J. Sewell, B. Aarabi, TM Scalea: Preliminary trial of a noninvasive brain acoustic monitor in trauma patients with severe closed head injury. In: The Journal of trauma. Volume 53, Number 5, November 2002, pp. 857-863, doi : 10.1097 / 01.TA.0000033745.86989.AC , PMID 12435935 .
  8. ↑ Wrobel et al .: On ultrasound classification of stroke risk factors from randomly chosen respondents using non-invasive multispectral ultrasonic brain measurements and adaptive profiles . 2015