2D SPLASH: a new method to determine the fatty infiltration of the rotator cuff muscles

Abstract

The objective of this paper is to quantify the fatty degeneration (infiltration) of rotator cuff muscles with a new spectroscopic FLASH (SPLASH) sequence. Before planned surgery (reconstruction or muscle transfer), 20 patients (13 men, 7 women; 35-75 years) with different stages of rotator cuff disease underwent an MR examination in a 1.5-T unit. The protocol consists of imaging sequences and a newly implemented SPLASH, which allows an exact quantification of the fat/water ratio with a high spatial resolution in an arbitrarily shaped region of interest (ROI). The percentages of fat in the rotator cuff muscles were determined. To determine statistically significant differences between the different stages of rotator cuff tear, a Kruskal-Wallis H test was used. Fatty infiltration of the supraspinatus muscle was correlated with cross-sectional area (CSA) measures (Bravais-Pearson). We found significant differences between different stages of rotator cuff disease, the fatty infiltration and the volume loss (determined by the occupation ratio) of the supraspinatus muscle. With the increasing extent of rotator cuff disease, fatty infiltration increases significantly, as does the volume loss of the supraspinatus muscle. Comparing fatty infiltration and the occupation ratio individually, there was only a moderate inverse correlation between fatty infiltration and the occupation ratio, with considerable variation of data. Fatty infiltration of the infraspinatus muscle occurred when the infraspinatus tendon was involved to a lesser extent. The SPLASH sequence allows exact quantification of fatty infiltration in an arbitrarily shaped ROI. The extent of atrophy and fatty infiltration correlates with the size of the tear. Atrophy and fatty infiltration correlate only moderately and should be evaluated separately.

Reliability of the Grading System for Fatty Degeneration of Rotator Cuff Muscles

“…Analysis of the muscle volume in cadavers using MRI with three-dimensional image analysis software and the actual volume after dissection correlate well, with intraobserver and interobserver variabilities less than 4% [26]. Two-dimensional SPLASH MRI and proton MR spectroscopy also were developed to quantify fat content of the rotator cuff muscles [12,17]. Fatty atrophy also was evaluated with ultrasonography [11,23].…”

“…Therefore, there have been attempts to develop a more objective method to measure muscle quantity and quality [12,26,28,29]. Measuring the mean muscle density in Hounsfield units in CT (ICC, 0.98) was superior to using a visual rating (ICC, 0.63) [28].…”

MR assessment of the repaired rotator cuff: prevalence, size, location, and clinical relevance of tendon rerupture

“…In addition, lack of oblique-sagittal T1-weighted sequences in some preoperative studies was a handicap that may have altered the reproducibility of fatty degeneration staging. Alternative techniques, such as the two-dimensional (2D) SPLASH sequence, may be used to obtain more accurate results in this regard [42]. Conventional axial gradient-echo sequences for postoperative MR imaging are certainly not state of the art but were used because preoperative imaging also included such sequences.…”

Changes in Appearance of Fatty Infiltration and Muscle Atrophy of Rotator Cuff Muscles on Magnetic Resonance Imaging After Rotator Cuff Repair: Establishing New Time-Zero Traits

“…Fatty infiltration and muscle atrophy are closely interdependent and are different manifestations of the same disease, but they are not perfectly correlated. 15,27 Therefore the preoperative prognostic implications of fatty infiltration and muscle atrophy, as well as their postoperative implications with respect to functional recovery, have been evaluated separately. 1 The reversibility of fatty infiltration after surgical repair still remains controversial.…”