無靜脈注射對比劑於低劑量電腦斷層掃描急性闌尾炎之診斷價值

許多研究皆證實，以多排偵測器電腦斷層掃描儀診斷急性闌尾炎是目前最有效率且準確的方式之一，並且普遍應用於各醫院急診室裡。急性闌尾炎好發於生育年齡的年輕人，病患所接受的輻射劑量應該要符合合理抑低原則。為了達到降低病患輻射劑量的目的，在本試驗中試著直接降低掃描條件，以一次性無靜脈注射對比劑方式，並固定120 kV，49 effective mAs的條件來做掃描，檢查前後完整記錄下病患的身體質量指數與影像雜訊值。請三位主治醫師與一位住院醫師各自作影像的診斷判讀。族群中有接受開刀者以外科手術以及病理組織學診斷作為確診的黃金標準；另則以臨床追蹤結果為依據。在九個月的期間內一共蒐集了106位病人，其中56位病患接受手術，有48位被證實患有急性闌尾炎。根據NCRP 160號報告，一般標準劑量全腹部電腦斷層檢查單次掃描平均為10毫西弗的有效劑量，而在本試驗中所有病患的有效劑量平均值與標準差僅為4.16±0.32毫西弗。經過分析之後的結果得到三位主治醫師在診斷準確率分別為90.6、86.8、91.5。以接受者操作特性曲線方式偵測判讀者之間的差異，得到曲線下面積分別為0.958、0.950、0.972，並且曲線接近。再以變異數分析的方式分析群體之間的關係，發現身體質量指數和雜訊值與主治醫師找出闌尾的位置並無統計學上的意義（p值大於0.05）。故本試驗推論，無靜脈注射對比劑於低劑量電腦斷層掃描急性闌尾炎之診斷價值，在於能大幅降低病患所接受到的輻射劑量，並且在主治醫師的判讀之下不失高度的準確性，亦不受身體質量指數和雜訊值所影響。

關鍵字

闌尾炎；低劑量；身體質量指數；多排偵測器電腦斷層掃描儀

並列摘要

In the past 10 years, CT has been proven as an accurate diagnostic tool for acute appendicitis. However, diagnostic radiation dose has become an issue of concern recently especially in the emergency department. Therefore, all radiological examinations should conform to the as low as reasonably achievable (ALARA) principle. All low-dose CT (LDCT) examinations were performed with a 64-detector CT (Toshiba Aquilion) at 120 kV, 49 effective mAs. No intravenous contrast medium or oral contrast medium was given for unenhanced LDCT. Body mass index (BMI) and CT noise of all patients were obtained by a technologist. Three attending radiologists and one resident radiologist who did not know the final diagnosis retrospectively reviewed all unenhanced LDCT independently using a five-point scale record sheet for acute appendicitis, and a three-point scale record sheet for the visualization of appendix. Surgical pathology or discharge diagnosis was the gold reference for comparison. Within a 9-month period, we prospectively included 106 emergency patients suspected of acute appendicitis who were referred to us for CT examination. Forty-eight of the 56 patients in the surgical operation group were classified as definite appendicitis. In this study, the mean effective dose and standard deviation were 4.16±0.32 mSv. According to NCRP 160 report, the average range of effective dose was 10 mSv by using standard-dose CT at whole abdomen per scan. In our study for attending radiologists, the diagnostic accuracy was 90.6, 86.8 and 91.5 respectively. In receiver operating characteristic curve (ROC curve) analysis, for detecting inter-observer's discrepancy, the area under the curve (AUC) was 0.958, 0.950, and 0.972 respectively. In analysis of variance (ANOVA), for detecting the relations of appendix visualization with BMI and noise, the result was no significant difference (p ＞ 0.05). Except for reducing radiation dose, in this study, the diagnostic value of unenhanced LDCT for acute appendicitis was accurate among attending radiologists, and visualization of appendix was not related to patient's BMI or CT noise.

並列關鍵字

appendicitis ； low dose ； BMI ； MDCT

國際替代計量

無靜脈注射對比劑於低劑量電腦斷層掃描急性闌尾炎之診斷價值

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