Summary

A new technique of fat quantification can specifically measure fat content of rotator cuff muscles and determine cuff chronicity and reparability

Abstract

Background.
The Goutallier method of measuring fatty infiltration is based on CT determination of broad levels of fat vs muscle, including “amount of fat = amount of muscle”. Recent articles discuss using MRI to determine the same levels as the Goutallier classification. With modern day computing abilities we should be able to assess muscle changes on a more accurate basis than the Goutallier classification

Methods.
MRI scans were taken of 148 patients of a single surgeon practice over a period of 27 months. These were then measured for rotator cuff fat quantification using a specific mDixon sequence developed on the Phillips MR 3T scanner (Olympic Park Imaging, Capitol). Unpublished reliability data shows excellent inter reliability of SSP, ISP, and Teres Minor assessment and good inter reliability for Subscapularis assessment. Rotator cuff patients were then assessed for repairability vs fatty percentage on “false colour” assessment of the fat (see diagrams).


Results.
Assessments of intact rotator cuffs all demonstrated fatty percentages of less than 10% in each of the muscles. Acute rotator cuff tears demonstrated a range between 10% and 20% of fatty percentage in rotator cuff muscle. In the few irreparable cuff tears scanned in this period, percentages of >20% were noted in the affected muscles.

Discussion

In the early assessments using this promising modality, we were able to flag likely irreparable rotator cuff tendon tears based on specific fatty percentage assesments of the cuff muscle, being much more accurate than the Goutallier classification.