Biomaterial Database

[Automated detection of microemboli in transcranial Doppler signals]. 1994

M Casty

BIOMAC Engineering Ltd., Frauenfeld, Schweiz.

The detection of micro-emboli (ME) in the intracranial brain arteries by means of transcranial Doppler sonography depends on signal quality and on the definition of the detection levels. The qualitative analysis by ear should be replaced by quantitative measurement techniques to provide results that are cross-comparable to the ones of other studies. Algorithms for ME detection have been developed and implemented on a Doppler signal analyzer. Three quantitative criteria were established with test data. Tape recordings of 44 middle cerebral arteries from an ongoing study including patients before and after implantation of prosthetic heart valves were examined. The data were first corrected for frequency response, phase and amplitude and examined by two independent investigators and by the instrument. Within the 44 measurements both examinations by ear found the same 26 samples to contain zero audible ME signals. The instrument detected in 21 cases zero ME signals, in 4 cases 1 signal and in 1 case 4 signals. For 18 tapes the ear-method provided counts of 1 to 160 ME's. In 12 cases the two investigators got the same result, in the remaining 6 cases the higher of both figures was selected for comparison to the automated count. The counting by the instrument was exactly the same for 7 cases, in 7 cases the instrument counted more, in 4 cases it detected fewer ME signals compared to the reference. The method and the proposed detection criteria provided more false positive than false negative results. This appeared to be due to artifact detection and on higher resolution in time leading to better separation of double events compared to the ear method. Assuming an adequate quality of the quadrature signals, the method may lead to automatic screening for ME signals.

UI	MeSH Term	Description	Entries
D007091	Image Processing, Computer-Assisted	A technique of inputting two-dimensional or three-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.	Biomedical Image Processing,Computer-Assisted Image Processing,Digital Image Processing,Image Analysis, Computer-Assisted,Image Reconstruction,Medical Image Processing,Analysis, Computer-Assisted Image,Computer-Assisted Image Analysis,Computer Assisted Image Analysis,Computer Assisted Image Processing,Computer-Assisted Image Analyses,Image Analyses, Computer-Assisted,Image Analysis, Computer Assisted,Image Processing, Biomedical,Image Processing, Computer Assisted,Image Processing, Digital,Image Processing, Medical,Image Processings, Medical,Image Reconstructions,Medical Image Processings,Processing, Biomedical Image,Processing, Digital Image,Processing, Medical Image,Processings, Digital Image,Processings, Medical Image,Reconstruction, Image,Reconstructions, Image
D011183	Postoperative Complications	Pathologic processes that affect patients after a surgical procedure. They may or may not be related to the disease for which the surgery was done, and they may or may not be direct results of the surgery.	Complication, Postoperative,Complications, Postoperative,Postoperative Complication
D002542	Intracranial Embolism and Thrombosis	Embolism or thrombosis involving blood vessels which supply intracranial structures. Emboli may originate from extracranial or intracranial sources. Thrombosis may occur in arterial or venous structures.	Brain Embolism and Thrombosis,Cerebral Embolism and Thrombosis,Embolism and Thrombosis, Brain
D003936	Diagnosis, Computer-Assisted	Application of computer programs designed to assist the physician in solving a diagnostic problem.	Computer-Assisted Diagnosis,Computer Assisted Diagnosis,Computer-Assisted Diagnoses,Diagnoses, Computer-Assisted,Diagnosis, Computer Assisted
D004867	Equipment Design	Methods and patterns of fabricating machines and related hardware.	Design, Equipment,Device Design,Medical Device Design,Design, Medical Device,Designs, Medical Device,Device Design, Medical,Device Designs, Medical,Medical Device Designs,Design, Device,Designs, Device,Designs, Equipment,Device Designs,Equipment Designs
D006350	Heart Valve Prosthesis	A device that substitutes for a heart valve. It may be composed of biological material (BIOPROSTHESIS) and/or synthetic material.	Prosthesis, Heart Valve,Cardiac Valve Prosthesis,Cardiac Valve Prostheses,Heart Valve Prostheses,Prostheses, Cardiac Valve,Prostheses, Heart Valve,Prosthesis, Cardiac Valve,Valve Prostheses, Cardiac,Valve Prostheses, Heart,Valve Prosthesis, Cardiac,Valve Prosthesis, Heart
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000465	Algorithms	A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.	Algorithm
D016477	Artifacts	Any visible result of a procedure which is caused by the procedure itself and not by the entity being analyzed. Common examples include histological structures introduced by tissue processing, radiographic images of structures that are not naturally present in living tissue, and products of chemical reactions that occur during analysis.	Artefacts,Artefact,Artifact
D017585	Ultrasonography, Doppler, Transcranial	A non-invasive technique using ultrasound for the measurement of cerebrovascular hemodynamics, particularly cerebral blood flow velocity and cerebral collateral flow. With a high-intensity, low-frequency pulse probe, the intracranial arteries may be studied transtemporally, transorbitally, or from below the foramen magnum.	Doppler Sonography, Transcranial,Doppler Transcranial Sonography,Doppler Transcranial Ultrasonography,Doppler Ultrasonography, Transcranial,Sonography, Transcranial Doppler,Ultrasonography, Transcranial Doppler,Neurosonology,Sonography, Doppler Transcranial,Transcranial Doppler Sonography,Transcranial Doppler Ultrasonography,Transcranial Sonography, Doppler,Transcranial Ultrasonography, Doppler,Ultrasonography, Doppler Transcranial,Neurosonologies