## What is diffusion coefficient MRI?

Apparent diffusion coefficient (ADC) is a measure of the magnitude of diffusion (of water molecules) within tissue, and is commonly clinically calculated using MRI with diffusion-weighted imaging (DWI) 1.

### What is a diffusion B value?

The b-value is a factor that reflects the strength and timing of the gradients used to generate diffusion-weighted images. The higher the b-value, the stronger the diffusion effects.

**What is diffusion in radiology?**

Diffusion weighted imaging (DWI) is a method of signal contrast generation based on the differences in Brownian motion. DWI is a method to evaluate the molecular function and micro-architecture of the human body.

**What is Tracer diffusion?**

Tracer diffusion, which is a spontaneous mixing of molecules taking place in the absence of concentration (or chemical potential) gradient. This type of diffusion can be followed using isotopic tracers, hence the name.

## What is T1 and T2 on brain MRI?

The most common MRI sequences are T1-weighted and T2-weighted scans. T1-weighted images are produced by using short TE and TR times. The contrast and brightness of the image are predominately determined by T1 properties of tissue. Conversely, T2-weighted images are produced by using longer TE and TR times.

### What is low ADC value in MRI?

Lower ADC values were associated with more aggressive tumor behavior. Therefore, the ADC value may represent a useful biomarker for assessing the biological features and possible relationship to the status of identified rectal cancers.

**Does ADC vary with B value?**

A biexponential fit should be a basic requirement, considering that DWI of the human body requires restricted diffusion [26, 34–38]. In this case, the ADC value is known to vary along with b values used for calculating the ADC [26, 27].

**What is B value in ADC?**

To sense slow moving water molecules and smaller diffusion distances, b values should be higher (e.g. b = 500 s/mm2). Apparent diffusion coefficient is calculated using different b-values (e.g 0-1000 s/mm2). A useful rule of thumb is to choose the b value such that (b X ADC) is nearly equal to 1.

## What is the difference between DWI and DTI?

While DWI refers to the contrast of the acquired images, DTI is a specific type of modeling of the DWI datasets.

### What is T1 and T2 in MRI?

**Why is diffusion coefficient important?**

The diffusion coefficient is an important variable in many diffusion equations that describes how quickly one material can diffuse through another material. Increasing temperature increases the diffusion coefficient, as demonstrated by the equation relating the diffusion coefficient to temperature.

**What is the interdiffusion coefficient?**

The interdiffusion coefficient is usually a composition-dependent quantity. On the other hand, interdiffusion is due to the diffusive motion of A and B atoms, which in general have different intrinsic diffusion coef- ficients.