| 1. |
- Jansson, Tomas, et al.
(författare)
-
Ultrasound Doppler for improved diagnosis of disease in the paranasal sinuses
- 2005
-
Ingår i: Proceedings - IEEE Ultrasonics Symposium. - 1051-0117. - 0780393821 ; 2, s. 839-841
-
Konferensbidrag (refereegranskat)abstract
- We propose a method to improve the diagnosis of infection in the paranasal sinuses, distinguishing between mucous and serous cases. The method utilizes a previously published method whereby the viscosity in a sealed container may be measured using an ultrasound Doppler method. As ultrasound propagates in a liquid medium, due to attenuation, the resulting pressure gradient will cause the liquid to move in the propagation direction - the wellknown effect of acoustic streaming. The streaming velocity will, for a given acoustic output, be proportional to the viscosity of the fluid. In this study, we verify that acoustic streaming can be induced in an anthropomorphic sinus phantom cast from a human cranium. The sinus phantom was made from agar with added graphite providing sound attenuation prior to the sinus cavity corresponding to an in vivo situation. A number of water-glycerol solutions with scattering particles, were prepared to mimic a clinically interesting range of viscosities (7-47 mPas). Using a 4.2 MHz continuous wave Doppler probe, clearly detectable mean Doppler shifts in the range of 6.5 to 20 Hz were recorded A linear relationship was found between the Doppler shifts and 1/viscosity (R2=0.94, corrected for the square-law dependence of sound speed variation due to varying glycerol concentration).
|
|
| 2. |
- Jönsson, Peter, et al.
(författare)
-
Feasibility of measuring acoustic streaming for improved diagnosis of rhinosinusitis
- 2008
-
Ingår i: Ultrasound in Medicine and Biology. - : Elsevier BV. - 0301-5629. ; 34:2, s. 228-238
-
Tidskriftsartikel (refereegranskat)abstract
- No noninvasive methods exist currently with the capability of distinguishing between various stages of a sinus infection. We studied a method based on induced acoustic streaming in the accumulated fluid within the maxillary sinuses. The hypothesis was that acoustic streaming will not be induced at clinically acceptable intensity levels in infectious mucous fluid because of its high viscosity, whereas detected acoustic streaming is a strong indication that the sinus content is a noninfectious serous fluid. As a model, an anthropomorphic sinus phantom with bovine cortical bone to mimic the bone surrounding the maxillary sinus was constructed. Milk (1.5% fat content) was used as model fluid. From fluid and bone attenuation measurements, an ultrasound frequency of about 5 MHz was estimated to produce the highest acoustic streaming in the sinus phantom. Simulations of the acoustic streaming in a sealed cavity also showed that the width of the ultrasound beam should be about half the size of the cavity to optimize the streaming velocity. With a 4.9-MHz continuous-wave transducer operating at a spatial peak temporal average intensity of 640 mW/cm(2), an acoustic streaming velocity of 0.19 cm/s was generated and detected in the sinus phantom.
|
|
