Enter the signal intensity, baseline signal intensity, and b-value into the calculator to determine the apparent diffusion coefficient (ADC).

Apparent Diffusion Coefficient Calculator

Enter any 3 values to calculate the missing variable

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Apparent Diffusion Coefficient Formula

The following formula is used to calculate the apparent diffusion coefficient (ADC) for a given set of values. 

ADC = -\frac{ln(S / S0)}{b}

Variables:

  • ADC is the apparent diffusion coefficient (mm²/s)
  • S is the signal intensity
  • S0 is the baseline signal intensity
  • b is the b-value (s/mm²)

To calculate the apparent diffusion coefficient, take the natural logarithm of the ratio of the signal intensity to the baseline signal intensity, and divide the result by the b-value.

What is Apparent Diffusion Coefficient?

The apparent diffusion coefficient (ADC) is a measure used in magnetic resonance imaging (MRI) to quantify the diffusion of water molecules within tissue. It is particularly useful in the diagnosis and characterization of various medical conditions, including stroke and cancer. The ADC value is derived from diffusion-weighted imaging (DWI) and reflects the degree of water diffusion within a voxel of tissue. Higher ADC values indicate greater water mobility, while lower values suggest restricted diffusion, which can be indicative of pathological changes in the tissue.

How to Calculate Apparent Diffusion Coefficient?

The following steps outline how to calculate the Apparent Diffusion Coefficient (ADC).

  1. First, measure the signal intensity (S) from the diffusion-weighted image.
  2. Next, measure the baseline signal intensity (S0) from the non-diffusion-weighted image.
  3. Determine the b-value (b), which is a parameter that reflects the strength and timing of the gradients used in the diffusion-weighted imaging sequence.
  4. Calculate the ADC using the formula: ADC = -ln(S / S0) / b.
  5. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Signal Intensity (S) = 500

Baseline Signal Intensity (S0) = 1000

b-value (b) = 800 s/mm²