以16多列式電腦斷層掃描儀評估顯影劑注射速率與體重影響於犬後大動脈顯影特性之研究

Abstract

研究目的： 本研究以16多列式電腦斷層掃描儀探討於兩種情況下顯影劑在犬隻後大動脈顯影的特性，包括： 1. 相同體重群犬隻，以不同顯影劑注射速率 2. 不同體重群犬隻，以相同顯影劑注射速率 期望瞭解顯影劑於犬隻血管顯影之特性，以擴大應用檢查範圍與標準化影像品質，進而增進獸醫臨床診療品質。 研究對象： 19隻臨床篩選非心臟血管疾病的犬隻，分為三組，A組與B組為統計上體重無明顯差異的犬隻，B組與C組為統計上體重呈現明顯差異的犬隻（C組>B組）。 研究方法： 將犬隻全身麻醉，腹側躺於多列式電腦斷層檢查台上，並以500mg I/kg之劑量經由頭靜脈給予濃度370mgI/ ml之非離子性顯影劑，同時在位於支氣管分叉同一平面之後大動脈處間隔掃描50次，所得影像以軟體計算出該處後大動脈顯影與時間之關係，三組施打顯影劑之速率如下：A組3ml/sec., B組4ml/sec.,和C組4ml/sec.。 研究結果： 三組顯影與時間的關係以直條圖和時間顯影曲線表示，在A組與B組中，B組較快到達最適顯影值（7.43 ± 1.01 秒），且有較高的最大顯影值（566.41 ± 56.13 HU），而A組有較長的最適顯影期間（12.8 ± 3.31 秒）。在B組與C組中，C組較慢達到最大顯影值時間（23.75 ± 2.7 秒），而B組的最適顯影期間較短（11.18 ± 2.47 秒）。 研究結論： 較快之顯影劑注射速率可較快達到最適掃描顯影值，且比低注射速率時能出現較高之最大顯影值，然而最適掃描期間會相對縮短。而越重之犬隻，達到最適掃描顯影值時間會延後，但其最適掃描期間較體重輕者較久。三組分別以時間顯影曲線顯示，其整體特性與人醫文獻之結果相類似，但明顯不同之處是時間顯影曲線明顯往左偏移。

Objective: To evaluate the effects of contrast medium in canine caudal aorta under 16- row multidetector computed tomography (MDCT) within two controlled variations, including: 1. Different contrast medium injection rate in two groups of similar body weight. 2. Two groups with different body weight administrate the same injection rate of contrast medium We expect to figure out the properties of contrast enhancement in the canine vascular system to improve the quality of contrast imaging, and to extend the applications of MDCT use in clinical veterinary medicine. Animals: Nineteen clients owned dogs without cardiovascular system diseases were collected and classified into three groups in this study. Group A and B were no statistically significant difference in body weight, and Group C were heavy than Group B. Material and method: All dogs were anesthetized and positioned in sternal recumbency under 16-MDCT scanning. The total dose 500mg I/kg non-ionic contrast medium (370mg I/ml) were then administrated via cephalic vein. The injection rate was 3ml/sec., 4ml/sec. and 4ml/sec. for Group A, B and C, respectively. We measured the attenuation values in Hounsfield Unit (HU) for the caudal aorta at the level of trachea bifurcation which can be showed on the image. Result: In Group A and B, while group B (7.43 ± 1.01 sec) is faster than group A (9.35 ± 0.61 sec.) in achieving at the point of optimal enhancement and also has higher maximum enhancement attenuation (566.41 ± 56.13 HU) , Group A has longer period for optimal enhancement (12.8 ± 3.31 sec.). Compare Group B to Group C, Group C (13.74 ± 0.83 sec.) is slower than Group B (7.43 ± 1.01 sec.) in achieving at the point of enhancement, and Group B has shorter period for optimal enhancement (11.18 ± 2.47 sec.) Discussion: With similar body weight, the faster injection rate (4ml/sec.), the shorter time to reach the attenuation of initial optimal enhancement as well as the higher attenuation of maximum enhancement and the shorter optimal enhancement period. At the same injection rate the heavy dogs delayed the initial time of optimal enhancement, but has longer optimal enhancement period. The results of three groups were showed in time-enhancement curve within which the entire properties were similar to the relative reports of human medicine. However, an obvious difference is that the time- enhancement curve shift leftward.