Ultrasonic instrument for accurate measurements of spatial parameters in blood vessels

Mani, Mohammad H. (2016) Ultrasonic instrument for accurate measurements of spatial parameters in blood vessels. PhD thesis, University of Nottingham.

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The present research is aimed at the development of an ultrasonic medical instrument capable of measuring the intima-media thicknesses (IMT) of artery walls that are considered by medical practitioners as good indicators of the risk of atherosclerosis. This overcomes two notable limitations of the instruments available at present – insufficient axial resolution and lack of synchronisation to the heart cycle that make the measurements difficult to use, e.g., for annual screening of patients and like-for-like comparisons. These limitations were addressed by using a combination of on-the-fly averaging and interleaved sampling for acquiring echo waveforms, and triggering the scans at a particular instant of the heart cycle. The developed electronic instrumentation consisted of a battery powered electrocardiogram (ECG) monitor that transmitted the ECG data using an infrared link to the ECG processor that triggered the scans. Such architecture eliminated any possibility of accidentally connecting the patient to a source of voltage capable of causing serious injury and of causing radio frequency interference to medical equipment located in a close proximity. The algorithm for detecting the R-waves from noisy ECGs was fully verified with simulated and experimental ECG records, and implemented in firmware on board the ECG processor. The rate of R-wave detection of the developed algorithm is 88.24% out of 204 heartbeats recorded.

In order to ease the interpretation of the recorded echoes, both mathematical and physical simulations of tubular objects were carried out. The calculated resolution of the system was estimated 2.5um. Spatial resolution of 15um was achieved during the in-vivo experiments. Some of the factors that might have caused this difference have been discussed with suggestions on possible methods of improvements. The set of experimental waveforms recorded in vivo demonstrated the correct operation of the developed instrument, appropriate consistency and some features that were expected and described in the literature. The developed instrument seems ready for application to a broader group of subjects.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Kalashnikov, A.
Hayes-Gill, B.R.
Keywords: Ultrasound, Intima-Media thickness, Ultrasound measurement, ECG, Artery thickness, Artery wall
Subjects: R Medicine > RC Internal medicine
Faculties/Schools: UK Campuses > Faculty of Engineering
Item ID: 33355
Depositing User: Mani, Mohammad
Date Deposited: 15 Jul 2016 06:40
Last Modified: 14 Sep 2016 17:15
URI: http://eprints.nottingham.ac.uk/id/eprint/33355

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