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 | |
| Status | Published |
Clinical Implementation
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.
Considerations for Dataset Development
Procedures(s): Cardiac MRI
View(s): Cardiac MRI with T1 mapping protocol
Sex at Birth: {Male, Female}
Hematocrit Lab Value: Varied
Technical Specifications
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 | |
| 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 | |
| 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 |