Main Content
Automated Calculation of TT-TG Distance
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Clinical Implementation
Value Proposition
The distance offset between the tibial tuberosity (TT) and the trochlear groove of the femur (TG) is one of several metrics used to assess the stability of the patellofemoral joint in cross-sectional imaging (CT and MRI). The anatomic landmarks are high contrast, distinctive in geometry and should be amenable to many forms of automatic identification. These landmarks used to define the TT-TG measurement are well-defined but the measurement is tedious to perform manually. An automated process to perform this measurement would be a time-saver for radiologists, is potentially more accurate, would increase the frequency with which the measurement is performed, and could assist in creation a large dataset of TT-TG values that might be used for future data-mining.
Narrative(s)
A 21-year-old patient is referred for a history of patellofemoral instability. The surgeon refers patient to perform an MRI.
Workflow Description
A MRI is taken and sent to PACS and the AI engine. The algorithm is triggered by MRI scan of the knee or manually triggered by the radiologist. Image is analyzed and returns the TT-TG distance.
The algorithm could follow the human radiologist process to measure this distance. For example, after identifying the posterior cortex of the femoral condyles, the center of the trochlear groove of the femur, and the tibial tuberosity. A simple geometric measurement is derived from those four points as follows:
- draw parallel line along the cortex of the femoral condyles
- draw perpendiculars to this line, bisecting the TT and the TG
- measure the transverse distance between these two perpendiculars (not the Euclidean distance)
For validation purposes, it is desirable to display the reference points from which the measurements are derived on key images from the study, with manual adjustment possible if the radiologist disagrees with the automated measurement.
Considerations for Dataset Development
| Procedures(s) | { MRI knee} |
| View(s) | {Axial} |
| Sex at Birth | {Male, Female} |
| Age | [15,90] |
Technical Specifications
Inputs
DICOM Study
| Procedure | MRI Knee |
| Views | Axial |
| Data Type | DICOM |
| Modality | MRI |
| Body Region | Lower Extremity |
| Anatomic Focus | Knee |
Primary Outputs
TT-TG Distance Measurement
| RadElement ID | RDE510 |
| Definition | Lateral offset of tibial tuberosity from center of trochlear groove femur |
| Data Type | Numeric |
| Value Set | N/A |
| Units | Millimeters |
Related Datasets
No known related public datasets at this time, please alert us if you know of any.