Most of the algorithms developed for object detection employ a background-subtraction technique which requires heavy computation. In this paper, we present a fast background-subtraction technique which can be readily applied to many existing object detection algorithms. The proposed technique consists of three parts: persistent background-subtraction, background-subtraction with nearby searchin...

Intracranial vessels were examined in 55 patients with both conventional selective catheterization and intravenous digital subtraction angiography using a prototype digital subtraction unit. In 65% of the patients, the digital subtraction angiogram was diagnostic, but the overall quality was inferior to conventional selective angiography. In 22%, the digital subtraction angiogram provided diagn...

to make an accurate estimation of the uptake of radioactivity in an organ using the conjugate view method, corrections of physical factors, such as background activity, scatter, and attenuation are needed. the aim of this study was to evaluate the accuracy of four different methods for background correction in activity quantification of the heart in myocardial perfusion scans. the organ activit...

A model of the signal path in arterial spin labeling (ASL)-based functional magnetic resonance imaging (fMRI) is presented. Three subtraction-based methods for forming a perfusion estimate are considered and shown to be specific cases of a generalized estimate consisting of a modulator followed by a low pass filter. The performance of the methods is evaluated using the signal model. Contaminati...

Analysis of Subtraction Methods in 3D Contrast-Enhanced MR Digital Subtraction Angiography Yuexi Huang Master of Science 2001 Department of Medical Biophysics University of Toronto 3D Contrast-enhanced MR angiography is promising as a replacement to catheter-based x-ray angiography due to its non-invasive nature. However, the image quality of MR angiography is still inferior to that of x-ray an...

conclusions the advantages of dsa in fluoroscopy-guided transforaminal epidural block and nerve block are identification of the degree of appropriate contrast flow (epidural and nerve root sleeve) and the intravascular administration without overlapping radiodense structures. introduction most pain physicians know that fluoroscopy might improve the safety, accuracy, and efficacy of nerve block;...

For 4 months, a prototype digital subtraction system was used to obtain images of the cerebral vasculature after intraarterial contrast injections. In 12 instances, the intraarterial injections were recorded with both a digital subtraction unit and conventional direct magnification film-screen system. The digital subtraction and conventional film subtraction images were compared and graded for ...