Left Ventricle T1 Mapping Quantification

Purpose	Report quantitative left ventricle myocardial T1 relaxation time, before and after IV contrast. Use these values to compute extracellular volume.
Tag(s)
Panel	Cardiac
Define-AI ID	18040018
Originator	Peter Filev
Panel Chair	Carlo De Cecco
Panel Reviewers	Cardiac Panel
License	Creative Commons 4.0
Status	Published

Value Proposition

Cardiac magnetic resonance has become a critical, noninvasive diagnostic tool for evaluating cardiac morphology, tissue, and function. The technique of T1 mapping has been shown to be effective in providing a quantitative assessment of the myocardial tissue and, in particular, offers increased sensitivity for detecting diffuse or infiltrative myocardial disease processes. Extracellular volume (ECV) has been shown to be a marker for myocardial tissue remodeling, which is quantifiable and can be computed using T1 mapping measurements before and after contrast. An algorithm can be developed that automatically reports the numerical T1 values obtained from the T1 map sequences, alerts the user if these measurements are outside of normal range, and also computes the ECV. The algorithm will compute an ECV map with a segmented left ventricle (LV) myocardium that is color scaled based on signal intensity.

Narrative(s)

A 45-year-old male with no past medical history is admitted from the ER with new onset heart failure. Acute myocarditis is suspected, and a cardiac MRI is obtained as part of the workup to confirm this diagnosis. The proposed algorithm demonstrates diffusely elevated precontrast T1 map values as well as diffusely elevated ECV values. Using these findings along with other findings (nonischemic late gadolinium enhancement pattern and decreased LV function), the radiologist/cardiologist is able to confirm a diagnosis of acute myocarditis.

Workflow Description

Cardiac MRI protocol with T1 mapping pre- and postcontrast is performed. A precontrast native T1 map image is generated as well as a postcontrast T1 map image. The radiologist is prompted to provide the patient’s hematocrit level. An ECV map image is generated. The LV myocardium is segmented in these images, which are color labeled based on their signal intensities. The images are in the short axis plane at the mid-heart level. For each of these images (T1 maps and ECV map), the algorithm draws 4 regions of interest (ROIs) of approximately 25 mm2, which are in the anterior wall, septum, inferior wall, and lateral wall. The average values and standard deviations of signal intensities are displayed, as well as the normal (expected) ranges (which may vary on scanner and magnetic field strength).

The algorithm prompts the clinician on what diagnosis is clinically suspected. The algorithm alerts the physician if the computed values (T1 map values and ECV values) as measured in the ROI meet the appropriate threshold for that diagnosis.

Procedures(s): Cardiac MRI

View(s): Cardiac MRI with T1 mapping protocol

 

Sex at Birth: {Male, Female}

 

Hematocrit Lab Value: Varied 

Inputs

DICOM Study

Procedure	Cardiac MRI
Views	Cardiac MRI with T1 mapping protocol
Data Type	DICOM
Modality	MR
Body Region	Chest
Anatomic Focus	Heart

Primary Outputs

Native T1

RadElement ID	RDE215
Definition	Native average T1 tissue as (average value from 4 ROIs)
Data Type	Numeric
Value Set
Units	ms

 

Extracellular Volume

RadElement ID	RDE216
Definition	Average ECV (average signal value from 4 ROIs)
Data Type	Numeric
Value Set	[0,100]
Units	Percentage

Secondary Outputs

Presence of Suspected Disease

RadElement ID	RDE217
Definition	Alert if calculated native T1 map value and ECV meet threshold for suspected cardiovascular disease
Data Type	Categorical
Value Set	0-Unknown 1-Suspected disease 2-No disease
Units	N/A

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