Real-time sonography to estimate muscle thickness: Comparison with MRI andCT

Purpose. We investigated the feasibility of using real-time sonography to m easure muscle thickness, Clinically, this technique would be used to measur e the thickness of human muscles in which intramuscular microstimulators ha ve been implanted to treat or prevent disuse atrophy. Methods. Porcine muscles were implanted with microstimulators and imaged wi th sonography, MRI, and CT to assess image artifacts created by the microst imulators and to design protocols for image alignment between methods. Sono graphy and MRI were then used to image the deltoid and supraspinatus muscle s of 6 healthy human subjects. Results. Microstimulators could be imaged with all 3 methods, producing onl y small imaging artifacts. Muscle-thickness measurements ag reed well betwe en methods, particularly when external markers were used to precisely align the imaging planes. The correlation coefficients for sonographic and MRI m easurements were 0.96 for the supraspinatus and 0.97 for the deltoid muscle . Repeated sonographic measurements had a low coefficient of variation: 2.3 % for the supraspinatus and 3.1% for the deltoid muscle. Conclusions. Real-time sonography is a relatively simple and inexpensive me thod of accurately measuring muscle thickness as long as the operator adher es to a strict imaging protocol and avoids excessive pressure with the tran sducer. (C) 2001 John Wiley & Sons, Inc.