Piccinini Filippo, Tesei Anna, Bevilacqua Alessandro
Advanced Research Center on Electronic Systems for Information and Communication Technologies "E. De Castro" (ARCES), University of Bologna, Bologna, Italy.
Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST), IRCCS, Meldola, FC, Italy.
Comput Methods Programs Biomed. 2016 Oct;135:51-60. doi: 10.1016/j.cmpb.2016.07.024. Epub 2016 Jul 18.
Cancer multicellular spheroids are commonly used as 3D tumour models for testing drugs and radiotherapy treatments. The volume plays a key role in analysis of the results. Several methods have been proposed in the literature to compute the spheroid's volume from one 2D microscopy image (i.e. a single projection). However, the literature lacks reviews summarising the different methods available. Furthermore, there are no well-established approaches by which to compare the different methods and determine the best one.
In this work we (a) revise the existing single-image based methods used to estimate the volume of multicellular spheroids, also providing different implementations for classical spherical and ellipsoidal pre-defined models; (b) present an upgrade of a volume estimation software recently proposed, Reconstruction and Visualization from a Single Projection (ReViSP), just validated by using four real spheroids imaged in 3D with a light-sheet microscope; (c) propose a quality assessing approach for single-image based methods, relying on 3D home-made macroscopic synthetic models mimicking the shapes of real multicellular spheroids.
Seven image-based methods used to estimate the volume of spheroids were compared using six 3D home-made synthetic models. First, the material used to make the synthetic models was characterised to estimate its density. Then, the ground-truth volume of the 3D models was measured by simply weighing them. The volume instances estimated by the different methods were compared with ground truth. ReViSP attained the best result three times out of six and on average.
The results obtained proved that (a) different implementations for the classical spherical and ellipsoidal pre-defined models may lead to very different results; (b) ReViSP is the best single-image based method available today to estimate the volume of multicellular spheroids.
癌症多细胞球体通常用作测试药物和放射治疗的三维肿瘤模型。体积在结果分析中起着关键作用。文献中已经提出了几种从一张二维显微镜图像(即单个投影)计算球体体积的方法。然而,文献中缺乏对现有不同方法的综述。此外,没有成熟的方法来比较不同的方法并确定最佳方法。
在这项工作中,我们(a)修订了用于估计多细胞球体体积的现有基于单图像的方法,还为经典的球形和椭圆形预定义模型提供了不同的实现方式;(b)展示了最近提出的体积估计软件“单投影重建与可视化”(ReViSP)的升级版,该软件刚刚通过使用光片显微镜对四个真实球体进行三维成像进行了验证;(c)提出了一种基于单图像方法的质量评估方法,该方法依赖于模仿真实多细胞球体形状的三维自制宏观合成模型。
使用六个三维自制合成模型比较了七种用于估计球体体积的基于图像的方法。首先,对用于制作合成模型的材料进行表征以估计其密度。然后,通过简单称重测量三维模型的真实体积。将不同方法估计的体积实例与真实值进行比较。ReViSP在六次中有三次且平均而言获得了最佳结果。
获得的结果证明:(a)经典球形和椭圆形预定义模型的不同实现方式可能导致非常不同的结果;(b)ReViSP是目前可用的用于估计多细胞球体体积的最佳基于单图像的方法。