Sono-CT a new diagnostic tool in ultrasonography of the orbit
T. Littan, P. Jacobi, W. E. Lieb
Introduction: Recently image quality in ultrasonography has significantly been improved. Broad spectrum instead of single frequency transducers and significant advances in processor speed and image processing have made compound imaging like in CT- and MRI- technology possible. SonoCT imaging begins within the scanhead generating "off-axis" ultrasound beams using a computed steering technology.
Out of the returning information the system processes 9 complete images from separate transmit angles. This information is digitally combined to create a single image.
Method: In 18 patients (44,3 ± 26,9 years) we performed an ultrasound examination of the eye and orbit. We used a conventional ultrasound system with a 10 MHz transducer (I3 system ABD® of the innovative imaging inc.) and a new generation ultrasound system with a broad band transducer (HDI® 5000 of the ATL company, transducer L 12-5 38) with and without sono CT.
Results: The new generation system is superior to the conventional system in detection of anterior structures like dermoid cysts. Image artefacts, as they occur in phtisis bulbi, are significantly reduced and delineation of solid orbital tumors is easier. Especially with Sono CT delineation of borders and interfaces of vitreous membranes and visualization of cystic contents and internal structures in solid lesions is improved.
Discussion: With the new technique a marked improvement in image quality and suppression of artefacts compared to the conventional system was revealed in our investigation. Sono CT is another step in the advances of equipment technology and digital image processing besides harmonic imaging and broadband transducers.
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