# Differences between 2D and 3D medical Images

I have two questions:

1. What is the difference between 2D and 3D medical images?

2. Assume I have a 2D image and for example it contains 1000 ROIs. Each ROI is a matrix and we can convert it to a vector.

When we have a 3D image how can I divide it to ROIs (what will be ROIs) and how can I convert every ROI to a vector?

## 1 Answer

I assuming that by ROI you mean an axis-aligned Region of Interest, with some 2D origin and width+height.
In this case, in a 3D volume, a ROI would by an axis aligned box with some 3D origin and a width, height and depth.

Once you have the box you can write out the voxel values inside it as a vector.

• my database includes 700 lung images with size 512*512*3 in matlab and for a 3D lung image of one person,i confused,what is the relation between those 700 images and a 3D image and how i can extract a voxel from them? – Alireza Esmailzehi Apr 29 '15 at 11:46
• What do you mean by 3D image? – Adi Shavit Apr 29 '15 at 11:48
• @Alireza Esmailzehi It seems to me that you do not fully understand your data. What kind of data is it (MRI, CT, ...)? I find it unlikely that you have true 3D datasets with only 3 images in the third dimension (maybe you have 3 2D images, or you have one 2D image and 2 parameter maps that are calculated from the same spatial domain by other means of measurement?) – M529 Mar 8 '16 at 19:53