Academic Journal
Improvement of image quality of transcranial Doppler ultrasound
| العنوان: | Improvement of image quality of transcranial Doppler ultrasound |
|---|---|
| المؤلفون: | Gupta, Shreyank |
| بيانات النشر: | École de technologie supérieure |
| سنة النشر: | 2021 |
| المجموعة: | École de technologie supérieure, Montréal: Espace ÉTS |
| مصطلحات موضوعية: | échographie médicale, ondes ultrasonores massives, échographie Doppler, traitement du signal, impédance acoustique |
| الوصف: | Transcranial Doppler (TCD) sonography is an ultrasound method that measures blood flow velocity (FV) from the cerebral vessels. The use of TCD sonography is highly attractive as a modality because of its non-invasive nature and portability. Although TCD is recommended in the clinics, its usage is hindered in cases like vasospasm, which requires blood flow rate calculation. Blood flow rate calculation requires accurate measurement of the diameter of the blood vessel, and it can only be calculated when the image quality is good. The problem with TCD lies in the low ultrasonic energy penetrating inside the brain through the skull which leads to a low signal-to-noise ratio. This is because of several effects including phase aberration, variations in the speed of sound in the skull, scattering, the acoustic impedance mismatch, and absorption of the three-layer medium made up of soft tissues, the skull, and the brain. Secondly, there is also an energy loss because of the texture of the temporal bone. This thesis seeks to mitigate such limitations firstly through the development of an analytical model that studies the effect of transmission losses because of the acoustic impedance mismatch on the transmitted energies as a function of frequency. To do so, the wave propagation model will be shown from the ultrasonic transducer into the brain. This model calculates frequency-dependent transmission coefficient for a given skin and bone thickness. This approach was validated experimentally by comparing the analytical results with measurements obtained from a bone phantom plate mimicking the skull. The results showed that there is a possibility to choose an optimized excitation frequency based on the skin and the bone thicknesses improving the image quality of TCD. Based on these results, Doppler experiments were performed on the flat bone phantom plate considering the acoustic impedance mismatch effect. The results allowed the visualization of FV in the blood vessel phantom for the selected frequencies for which there is a ... |
| نوع الوثيقة: | article in journal/newspaper thesis |
| وصف الملف: | application/pdf |
| اللغة: | English |
| Relation: | https://espace.etsmtl.ca/id/eprint/3056/1/GUPTA_Sheyrank_v6.pdf; Gupta, Shreyank (2021). Improvement of image quality of transcranial Doppler ultrasound. Thèse de doctorat électronique, Montréal, École de technologie supérieure. |
| الاتاحة: | https://espace.etsmtl.ca/id/eprint/3056/ https://espace.etsmtl.ca/id/eprint/3056/1/GUPTA_Sheyrank_v6.pdf |
| رقم الانضمام: | edsbas.6DE6D5F1 |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |