Medical Imaging Dictionary

Voxel: A voxel represents a value on a regular grid in three-dimensional space

Pixel: A pixel is the smallest unit of a digital image or graphic that can be displayed and represented on a digital display device.

Deep Neural Network (DNN): an artificial intelligence system modeled on human brain where through a hierarchy of layers, the model learns low to high features of the input. Convolutional Neural Network (CNN): type of DNN adopted for imagery input. Number of parameters in a CNN is significantly less than that of a DNN due to a parameter sharing architecture made feasible by convolutional operations.

FLAIR image: an MRI pulse sequence that suppresses fluid (mainly cerebrospinal fluid (CSF)) while enhancing edema.

Diffusion weighted image (DWI): MR imaging technique measuring the diffusion of water molecules within tissue voxels. DWI is often used to visualize hyper intensities.

Proton density weighted (PDW) image: MR image sequence used to measure the density of protons; an intermediate sequence sharing some features of both T1 and T2. In current practices, PDW is mostly replaced by FLAIR.

T1-weighted image: one of the basic MRI pulse sequences showing the difference in the T1 relaxation times of tissues.

T1 Contrast-enhanced image: a T1 sequence acquired after a gadolinium injection. Gadolinium changes signal intensities by shortening the T1 time in its surroundings. Blood vessels and pathologies with high vascularity appear bright on T1 weighted post gadolinium images.

T2-weighted image: one of the basic MRI pulse sequences. The sequence highlight differences in the T2 relaxation time of tissues.

High-grade glioma: malignant brain tumors of types 3 and 4.

Low-grade glioma: slow growing brain tumors of types 1 and 2.

MICCAI: is an International Conference on Medical Image Computing (MIC) and Computer Assisted Intervention (CAI) which has two parts MIC and CAI held annually since 1997.

ISBI: is an IEEE International Symposium on Biomedical Imaging since 2002.