Mazonakis Michael, Damilakis John, Maris Thomas, Prassopoulos Panos, Gourtsoyiannis Nicholas
Department of Medical Physics, University Hospital of Iraklion, Iraklion, Crete, Greece.
J Magn Reson Imaging. 2002 May;15(5):557-63. doi: 10.1002/jmri.10109.
To compare the conventional technique of manual planimetry with the point counting technique for estimating liver volume from magnetic resonance imaging (MRI) data.
This study comprised abdominal MR examinations of 38 consecutive patients. Evaluation of the images showed that liver size appeared normal in 27 patients and increased in 11. Liver volume was estimated using the techniques of planimetry and point counting. Both techniques were used in combination with the Cavalieri method of modern design stereology. A systematic slice sampling procedure was performed to estimate liver volumes using both volumetric techniques. The point counting technique was optimized by altering the point spacing of the grid. The agreement between the two techniques was found. Measurement repeatability of both volumetric techniques was also evaluated.
Both techniques allowed the same degree of optimization through the procedure of systematic section sampling. The application of a point spacing of 2.5 cm reduced the time measurement by a factor of 3.5 in relation with the time needed with planimetry. An excellent agreement was observed between the two volumetric techniques with mean differences (+/-SD) of 2.4 +/- 41.6 cm(3) and 8.5 +/- 49.8 cm(3) for the patients presenting normal and increased liver sizes, respectively. Both techniques were highly reproducible.
The point counting technique could be considered a more efficient approach than planimetry for estimating liver volume from MRI, due to its speed and simplicity.
比较传统的手工平面测量技术与点计数技术，以从磁共振成像（MRI）数据估计肝脏体积。
本研究纳入了连续38例患者的腹部MR检查。图像评估显示，27例患者肝脏大小正常，11例增大。使用平面测量技术和点计数技术估计肝脏体积。这两种技术均与现代设计体视学的卡瓦列里方法结合使用。采用系统切片采样程序，使用这两种体积测量技术估计肝脏体积。通过改变网格的点间距对点计数技术进行了优化。发现了两种技术之间的一致性。还评估了两种体积测量技术的测量重复性。
通过系统切片采样程序，两种技术都实现了相同程度的优化。与平面测量所需时间相比，应用2.5 cm的点间距可将测量时间缩短3.5倍。对于肝脏大小正常和增大的患者，两种体积测量技术之间观察到极好的一致性，平均差异（±标准差）分别为2.4±41.6 cm³和8.5±49.8 cm³。两种技术都具有高度的可重复性。
由于其速度和简便性，点计数技术在从MRI估计肝脏体积方面可被认为是比平面测量更有效的方法。
