Measurement of Relative Blood Flow by the Video Dilution Technique ...

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blood flow (RBF). uipment: Apple II, 48K, one disk drive, and a. Mountain Computer Inc. A/D + D/A board. Language: Applesoft BASIC & 6502 machine language ...
MEASUREMENT OF RELATIVE BLOOD FLOW BY THE VIDEO DILUTION TECHNIQUE WITH THE AID OF A MICROCOIPUTER Michael L. Richardson MD, Daniel P. Link MD, Bruce A. Porter MD, and Bo M.T. Lantz MD Dr. Richardson:

All others:

c/o 5467 Plantain Circle, Orangevale, CA 95662

c/o Department of Radiology, University of California, Davis, CA

Description: The video dilution technique (VDT) has been shown to be a valuable tool in assessing blood flow during arteriography. This technique has been improved with the aid of an inexpensive microcomputer, which is used to digitize and store data from a videodensitometer (VDM) and to automatically calculate relative blood flow (RBF).

a vessel. This curve is digitized in real-time by an Apple II microcomputer (Apple Computer Co., Cupertino, CA) which also measures the curve area and calculates relative blood flow. Our current system cost about $2500.

Results

Our current system is fast and accurate. Once a curve has been digitized, the calculated relative blood flow is available seconds later. With the previous paper strip chart recorder and mechanical planimeter for measuring curve areas, such calculations took several minutes. Blood flow measurements with this system are extremely close to those measured by an electromagnetic flowmeter, with a coefficient of correlation of Curve area measurements by the computer are more precise than those done by hand on the planimeter, and data storage is more compact. One 5 1/4 inch floppy disk can store about the same number of curves as 500 feet of strip chart paper.

uipment: Apple II, 48K, one disk drive, and a Mountain Computer Inc. A/D + D/A board. Language: language.

Applesoft BASIC & 6502 machine

Availability: Program listings are available in return for an s.a.s.e. Introduction

Arteriography is widely used to obtain anatomic information in patients with vascular disease. However, one can understand a patient's condition much better if one can accurately measure the blood flow through a lesion. With such measurements, one can determine the hemodynamic significance of peripheral vascular disease or arteriovenous malformations. They can also be used to measure the effect of vasoactive drugs and percutaneous transluminal angioplasty upon vessels. Prior to the development of the VDT, obtaining such me,fsurements was not a simple or a convenient task .

Discussion The addition of a microcomputer solves several current problems of the VDT. By eliminating the strip chart recorder and mechanical planimeter in our old system, RBF measurements are obtained in seconds instead of minutes. By adding a commercially available real-time video *digitizer board and gray scale display system, we hope to someday have the microcomputer able to perform the functions of the VDM unit as well.

However, the VDT currently requires a VDM unit, which is not yet commercially available. With the addition of an inexpensive microcomputer, we are attempting to make the VDT even more convenient, and to make a VDT system easier for others to duplicate.

References Link DP, Foerster JM, Lantz BMT, 1. Holcroft JW. Assessment of peripheral blood flow in man by video dilution technique: a preliminary report. Invest Radiol 1981;16:298.

Methods The method we use is almost identica to that previously reported by Lantz et al ) . A small bolus of contrast is injected into the vessel of interest and into a reference vessel (usually the aorta). Each injection is recorded during fluoroscopy with a videotape recorder. The videotape is then replayed into a VDM. The VDM outputs a videodilution curve, whose area is inversely proportional to the blood flow within

2. Lantz BMT, Foerster JM, Link DP, Holcroft JW. Determination of relative blood flow in single arteries: new video dilution technique. AJR 1980;134:1161.

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0195-4210/82/0000/0648$00.75 © 1982 IEEE