# CA Quantifier

Class: NodeCAQuantifier

Calculates contrast agent (CA) concentration map based on a $$T_1$$ map [ms] a baseline signal (signal at zero Ca concentration) and dynamic data acquired during which CA is present in the imaged region. All images must correspond to the same region and Baseline and Dynamic Series must have the same settings. An optional mask can also be provided to limit the calculations to a region.

The following signal models are supported:

CA concentration is found from the ratio of the dynamic signal and the baseline signal by inverting the spoiled gradient echo equation(ignoring $$T_2^*$$-effects).

Saturation Recovery

CA concentration is found by using the signal equation

$$S=S_0(1-\exp(-T_I/T_1))$$

and a ratio between baseline ($$S_0$$) and dynamic signal ($$S$$). In the signal equation T1 is related to the contrast concentration $$C$$ through

$$T_1^{-1} = T_{10}^{-1} + r_1C$$

In these two equations $$TI$$ is the saturation delay (referred to as inversion time in the DICOM data) and $$T_{10}$$ is the $$T_1$$ without contrast agent.

Outputs a CA concentration map [mM].

## Inputs

#### T1

Input T1 map.

Type: Image4DFloat, Required, Single

#### Baseline

Input baseline image.

Type: Image4DFloat, Required, Single

#### Dynamic Series

Input dynamic series.

Type: Image4DFloat, Required, Single

Type: Image4DBool, Optional, Single

## Outputs

#### CA

Resulting contrast agent concentration map.

Type: Image4DFloat

## Settings

#### Model Selection

Signal model.

Values: SPGR, SaturationRecovery

#### R1 (mM¯¹s¯¹) Number

T1 relaxivity of the CA.

#### Set Undefined Numbers To Number

Undefined values(failed fits) are set to this value.

## References

1. Schabel and D. L. Parker, “Uncertainty and bias in contrast concentration measurements using spoiled gradient echo pulse sequences,” Phys. Med. Biol., vol. 53, no. 9, pp. 2345–2373, May 2008
1. Blüml Msc, Stefan & R. Schad, Lothar & Stepanow, Boris & J. Lorenz, Walter. (1993). Spin-lattice relaxation time measurment by means of a TurboFLASH technique. Magnetic Resonance in Medicine. 30. 289 - 295. 10.1002/mrm.1910300304.

Keywords: dce, dynamic, contrast, enhanced, t1, map