Post processing of computed tomography

post processsing in computted tomography

1. Post processing of computed tomography by: neha singh mrit 3 rd semester

2. Contents: 1. introduction 2. multiplanar reconstruction 3.curved planar reconstruction 4.maximum intensity projection Minimum intensity projection Volume rendering Surface shaded display References Questions

3. What is image post processing? It refers to the use of various technique { image processing software and algorithm} that modify the reconstructed images displayed for viewing and interpretation .

4. Significance of post processing : Post processing of CT images has been valuable tool in variety of clinical application due to its ability to provide additional diagnostic information. It has application in various organ and system such as chest, abdomen, brain, spine etc. It is essential to have the original data of excellent quality, to perform a post processing. This technique allow us to obtain anatomical information from original images and also gives us functional and molecular information.

5. After acquiring image data, it can be reconstructed and subjected to a variety of post processing techniques. In spiral CT axial image can be reconstructed at any point along the spiral path. Conventional CT section obtained 5mm collimation can only be reconstructed at 5mm intervals, where the spiral section acquired 5mm collimation can be reconstructed every 5mm, 1mm even at submillimeter intervals. 3D rendered images provide views of the imaging volume from different angles. True 3D image are not always necessary for diagnostic purpose.

6. Different types of post processing technique: There are six different techniques for post processing: Multiplanar reconstruction Curved planner reconstruction Maximum intensity projection Minimum intensity projection Surface shaded display Volume rendering

7. Multiplanar reconstruction: MPR allows images to be reconstructed from the original axial plane in either coronal, sagittal, or oblique plane. Spiral CT has greatly improved the quality of MPR by limiting the stair steps artefacts that used to occur with conventional slice by slice scanning. Multi-slice CT has further improved the quality of MPR as it allows isotropic imaging in which the quality of reconstructed image is similar to the original axial image.

8. Uses of MPR: MPR is most widely used post processing 3D application. It is used in MRI, CT and nuclear medicine study. It gives good visualization on images.

9. Curved planar reconstruction: It also called curved multi-planner reconstruction of curved MPR. CPR represents a single voxel thick tomographic section and are prescribed by drawing a curved on either axial section and reformatted section. It involves the tracing a structure, usually blood vessel, ureter etc.

10. Maximum intensity projection: It is a simple 3D visualization tool that can be used to display angiographic data. MIP is the data visualizing method that enables detection of highly intense structure. MIP displays the higher CT number in a volume of interest when projected into a new plane. MIP images generated by casting imaginary ray through the volume data set from a given viewing direction.

11. Uses of maximum intensity projection: MIP reconstruction is mainly used to show the vessels with contrast material in CT angiography to provide clear view of lesions. The primary clinical application of MIP is to improve the detection of pulmonary nodules.

12. Minimum intensity projection: It is a data visualizing method that enables detection of flow density structure in a given volume. It enables detection of low-density structures. 2D image of a selected volume is generated where each pixel is represented by displaying the lowest attenuation value in each voxel.

13. Use of minimum intensity projection: It is mainly used to diagnose lung diseases. For example: traction of bronchiectasis and emphysema.

14. Volume rendering: It is a process in which a computer programmer uses the acquired data to generate a recognizable 3D image. Volume rendering technique enables edge enhance visualization from an extra luminal perspective or endoscope. The advantage of VR that it allows visualizing the structure beyond the surface along with vascular anatomy. it is used to detect any blockage in vessels and fracture.

15. Surface shaded display: SSD is surface rendered image that provide a realistically looking 3D view of the surface of interest within the acquired volume rest. SSD uses less than 10% of original data in 3D plane

16. Reference: Radio- pedia Computed tomography: Euclid seeram .

17. Questions : 1. what is use of minimum intensity projection? 2. SSD stands for? 3.what is the use of curved planar projection?