Automated Calculation of TT-TG Distance

Purpose	Provide automated measurement of common metric for assessment of patellofemoral instability
Tag(s)
Panel	Musculoskeletal Panel
Define-AI ID	19050025
Originator	Dan Chernoff
Lead	Dan Chernoff
Panel Chair	Jay Patti
Panel Reviewers	Musculoskeletal Panel
License	Creative Commons 4.0
Status	Public Commenting
RadElement Set	RDES87

                               

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.

Procedures(s)	{ MRI knee}
View(s)	{Axial}
Sex at Birth	{Male, Female}
Age	[15,90]

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