本研究之目的是於常規腹部多切面電腦斷層，有注射顯影劑與無注射顯影劑將腰部椎體(第一節至第四節)利用定量電腦斷層分析出其骨質密度，並評估組間及組內之再現性，且比較無注射顯影劑與有注射顯影劑時，其椎體之骨質密度之差異。收集51位(男性34位, 女性17位)，平均年齡50.2歲，於常規無注射顯影劑與有注射顯影劑之腹部電腦斷層，由兩位有經驗之放射師在一個月內將第一節至第四節腰椎椎體各分析兩次。利用線性廻歸及Bland and Altman plot統計分析其結果。發現椎體骨質密度在無注射顯影劑定量電腦斷層於組內及組間有高度之再 現性(平均骨質密度105.30 g/cm3)，且可應用在臨床之常規作業上。此次所得結果注射顯影劑與無顯影劑注射尚可運用一轉換係數而得其互相關係：BMDCECT = 0.9871 x BMDNECT + 1.6575。

This study performs quantitative computed tomography (QCT) of the spine using noncontrast-enhanced (NE) and contrast-enhanced (CE) standard abdominal multidetector computed tomography (MDCT) data sets for bone mineral density (BMD) assessment based on volumetric QCT data sets. The reproducibility of intraobserver and interobserver measurements of vertebral bone mineral density (vBMD) are assessed using phantom-less quantitative computed tomography (PL-QCT) in clinical CT scan, and the differences in vBMD values are compared between NECT and CECT. Fifty-one patients (34 men, 17 women) with a mean age of (50.2±13.5 SD) years, underwent routine no contrast and contrast-enhanced abdominal MDCT, standard volumetric QCT of the spine (L1-L4). Two hundred and four vertebrae were measured by two experienced technologists two times. The measurement interval was within one month. Relations between QCT and contrast-enhanced MDCT findings were assessed using linear regression and Bland and Altman plot analysis. The vertebral BMD measurements from NECT QCT exhibited high intra-observer and inter-observer reproducibility, (the mean BMD were 105.30 g/cm3 by two readers) and could be used for clinical work-up. With conversion factor application, conversion Factor: BMDCECT = 0.9871 x BMDNECT + 1.6575, the BMD measurements could be calculated for the spine from routine abdominal MDCT data set.