Title

數位化血管攝影的影像扭曲現象及其對血管大小測量之影響

Translated Titles

Image Distortion on Digital Subtraction Angiography and Its Impact on Measuring Sizes of Blood Vessel

Authors

朱偉發(Wei-Fa Chu);鄧木火(Michael Mu-Huo Teng);沈達亮(Ta-Liang Shen);郭萬祐(Wan-You Kuo);葛平夷(Ping-Yi Ko);葉靜政(Ching-Cheng Yeh);施俊哲(Jyuh-Jer Shih);張豐基(Feng-Chi Chang);姜仁惠(Jen-Huey Chiang);張政彥(Cheng-Yen Chang)

Key Words

血管攝影 ; 技術 ; 影像 ; 扭曲 ; Angiography ; technology ; Images ; distortion

PublicationName

中華放射線醫學雜誌

Volume or Term/Year and Month of Publication

30卷2期(2005 / 05 / 01)

Page #

95 - 101

Content Language

繁體中文

Chinese Abstract

在放射線血管攝影介入性診療過程中常需要用血管攝影影像測量血管的長度與寬度,以作為選擇使用支撐架(stent)長度與寬度以及使用栓塞之線圈(coil)大小之參考。我們研究血管攝影影像上之扭曲現象與在不同位置會有不同比率放大之現象。 首先我們抽出側面(lateral plane)影像增感器前面之防散射線格柵(anti-scatter grid),以校準格柵(grid Plate為有一公分正方金屬刻度之格子模板)插入槽內替代之,固定×光管球至影像增感器之間距離為135公分,並保持C臂(C-arm)角度位置為水平角度,分別使用四種不同大小模式;12英吋、9英吋、6英吋、4.5英吋攝取影像,取得影像後,將四組不同大小模式影像傳送到工作站(workstation 3.1)進行測量。我們測量影像不同位置縱向與橫向之二公分格線線段之畫素(pixels)值。每一線段各量測三次以計算量測者內部的可信度。 我們發現這些影像有扭曲現象與在不同位置會有不同比率放大之現象。放大倍數可達1.41倍且在周圍最明顯。這些現象最明顯為使用12英吋大影像增感器時。此種扭曲與放大之現象因為pincushion distortion及S distortion所造成。 當我們用數位化血管攝影的影像作為量取血管長度與寬度時,標準公分之刻度應盡可能靠近量測處,使影像扭曲現象之影響減至最少。如位置不同時要考慮放大倍數之差異。

English Abstract

In radiological intravascular interventional we often need to know sizes of arteries from angiograms. For carotid stenting, we need to know information about the width and length of stent to be used. For aneurysm embolization, this information is necessary for us to decide the size of coil. We study the distortion and magnification ratio in different locations of the angiogram. We replace the anti-scatter grid with a grid plate with 1 cm markers inside on the lateral arm of the angiogram. We took lateral projection with 4 modes (12, 9, 6, and 4.5 inches) separately, keeping a constant distance of 135cm between the tube and the image intensifier, and holding the C-arm of the lateral projection horizontally. Then we measured the pixel size of a 2cm length grid in vertical and horizontal orientations in different parts of the angiogram. We did each measurement for 3 times for calculation of intra-observer reliability. We found the distortion and magnification are most obvious on peripheral portion of the image. The magnification ratio may increase up to 1.41 times at the periphery of the image. The distortion and magnification are because of pincushion distortion and S distortion. When the site of the artery to be measured and the ruler are in different locations of the angiographic image, we have to consider the distortion and variation in magnification ratio when we measure the width and length of the artery.

Topic Category 醫藥衛生 > 基礎醫學