- 學位論文
甲狀腺超音波對於診斷甲狀腺結節良惡性的臨床價值
Diagnostic Value of Ultrasonography to Distinguish Benign from Malignant Lesion in the thyroid Nodules
摘要
研究背景 一般人大約有百分之五有明顯的甲狀腺結節，而根據大規模的解剖學研究，大約百分之五十的人有甲狀腺結節，根據各家統計，解剖學研究所見之甲狀腺結節約有百分之五到百分之十為甲狀腺惡性腫瘤。高解析度超音波問世後，因超音波檢查的費用低廉，且無副作用，使得臨床醫療人員大量使用超音波，並配合甲狀腺細針抽取細胞學檢查之應用，甲狀腺癌發生率因而年年上升。在此情況下，如何以最經濟、最安全、最沒有侵入性的診斷工具，篩檢出最需要接受手術的病人；或是在多發性結節中找出最適合做為甲狀腺細針抽取細胞學檢查的標的，一直是臨床醫師想要達成的目標。 研究目的 在甲狀腺超音波的參數中，超音波回音(echogenicity )，結節邊界( margin)，微小型鈣化( microcalcification )，明顯型鈣化( macrocalcification )，頸部淋巴結增生(neck lymph nodes)，最大結節大小(size)是最常被提及與甲狀腺癌有關的項目，我們試著發現它們的臨床應用價值。 研究方法 我們在這次的研究當中，利用回溯性的方法，在2009年 1月1日至 2010年12月31日為止，所有在彰化基督教醫院接受甲狀腺切除的病歷都予以回顧，並且將病例分為惡性組與良性組，分別記錄病歷號碼、性別、年齡、手術日期、甲狀腺細胞學報告以及病理報告，甲狀腺超音波檢查參數的紀錄包括超音波回音(echogenicity ) 、結節邊界( margin) 、微小型鈣化( microcalcification ) 、明顯型鈣化( macrocalcification ) 、頸部淋巴結增生(neck lymph nodes) 以及最大結節大小(size) 1-28。從甲狀腺超音波的檢查參數與手術病理報告進行比較，以及良性組與惡性組的檢查結果利用統計學的幫助，找出各個檢查參數的敏感性，特異性，陽性預測率，陰性預測率，陽性概似比，陰性概似比。 研究結果 在甲狀腺超音波檢查各個參數及病理報告結果用Chi-Square以及2-sample t test加以進行統計，結果發現甲狀腺惡性腫瘤在惡性組與良性組之間、年齡分布、男女性別比、結節大小、頸部淋巴結之有無均無意義上的差別，但在結節邊界清晰度(margin) 、微小鈣化(microcalcification) 、以及結節超音波回音(echogenicity)這三個參數呈現有意義的差別，如果這三個參數在同一個病患同時存在兩個以上則其敏感度到達92%，特異度到達98%，藉此我們希望可以應用在臨床上，可因此減少侵入性的甲狀腺檢查，特別是甲狀腺細針細胞學抽取檢查與甲狀腺手術，而在多發性甲狀腺結節細針抽取細胞學檢查時，可以更精確的選定目標。 結論 到目前為止尚無單獨一個甲狀腺超音波的特徵足以成為甲狀腺癌的指標。甲狀腺結節細針抽取細胞學檢查一向被認為是甲狀腺結節最佳診斷工具之一，但是甲狀腺結節細針抽取細胞學檢查具有侵入性，而且約有1.6-31%的無法診斷率及約有21%偽陰性率再加上因為超高頻超音波的使用，一些小至1~2mm的甲狀腺結節都可發現，如果要對如此小的結節也加以細胞學檢查，不實際也不符合成本效率原則。 在本研究中發現低超音波回音(hypoechoic)，微小鈣化(microcalcification)，邊界模糊(ill-defined margins)，都是很好可以利用來預測甲狀腺結節良惡性的參數。在臨床上可加以利用做為單一結節，多發性結節，結節複診，術後追蹤時細針抽取細胞學檢查目標的選取，更進而可做為是否手術的參考。
並列摘要
Background:High-frequency sonographic imaging is now widely used in evaluation of the thyroid gland which led to the detection of a large number of non-palpable thyroid nodules in the general population. It has been estimated that 40% to 50% of the population will have a thyroid nodule found incidentally on sonography when performing examination of the neck lymph nodes, carotid arteries or other structures of the neck. Yet only about 5% to 6.5% of these nodules will represent malignant disease on further workup. Biopsy of all incidentally detected thyroid nodules with sonographically guided fine-needle aspiration (FNA) would not be cost-effective and would have a very low yield in discovering the very small proportion that truly have malignant disease. Objective: The goal of the study was to find an examination of nodular disease of the thyroid that will avoid costly evaluation in most patients who have benign disease and without missing the patients who have thyroid cancer. Most of surgeons evaluate palpable thyroid nodules by sonographically guided fine needle aspiration biopsy to rule out malignancies. However, to find cost-effective way to further workup of non-palpable incidentally found thyroid nodules remains an area of much debate in clinical practice. There were studies try to identify sonographic features that are sensitive and specific for malignant thyroid nodules. Sonographic features that have been suggestive of malignancy include hypoechogenicity, ill-defined margins, the presence of neck lymph nodes and the presence of microcalcifications. We conducted a IRB-proved retrospective study from Jan. 1 2009 to Dec. 31 2010. The purpose of this study was to evaluate the correlation between sonographic features that were suggestive of risk for malignancy and the results of the surgery pathology. Methods and Materials: An intragroup analysis of various sonographic features was conducted for comparison of common characteristics among benign and malignant nodules. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratios and negative predictive ratios are all calculated. In addition, we reviewed journals referring criteria for distinguishing between benign and malignant thyroid nodules on sonography. We performed this study with an attempt to assess the overall sensitivity and specificity of these sonographic parameters to find a economic way to predict the diagnosis of the thyroid nodules. Results:A total of 299thyroidectomies were reviewed. 101 thyroid cancers and 198benign thyroid nodules. Considering of ultrasound feartures of nodules, risk factors predicting malignancy were ill-defined margins, hypoechoic goiter texture and microcalcification. When two or more risk features combined, the sensitivity and specificity were 92% and 98% respectively. Conclusions:This study demonstrates the potential value of ultrasonography in predicting malignancy in a selected group of thyroid nodule patients. Malignancy risk could be determined according to US findings. Particularly, the risk is high in case of a combination of margin irregularity,hypoechoic texture, and microcalcification. Nodule size alone is not a reliable indicator of benign or malignancy. To define the strength and limitations ofultrasonography, further large-scale studies regarding the accuracy of ultrasonography using more objective ultrasonography criteria are required.