Brightness of deltoid muscle can give clues to diabetes status The echogenic appearance of the deltoid muscle makes it possible for doctors to determine, with good (but not perfect) accuracy, whether a patient complaining of shoulder pain has unrecognized diabetes, researchers suggested. When radiologists attempted to determine whether a person was diabetic on the basis of shoulder brightness observed on ultrasound, the positive predictive value was 89%, according to Kelli Rosen, DO, a resident in diagnostic radiology at Henry Ford Hospital in Detroit. "We were able to get a diagnosis of either definite diabetes or suspected diabetes in 106 out of 137 subjects who actually had a diabetes diagnosis – a 77% sensitivity," Rosen said when presenting her data at the Radiological Society of North America annual meeting. For the study, the researchers asked independent radiologists trained in musculoskeletal diagnoses if the shoulder sign would allow them to determine if patients were diabetic or not. The team reviewed charts of 137 patients with a diagnosis of type 2 diabetes, 13 patients received a diagnosis of pre-diabetes and 49 obese individuals were non-diabetic. "At Henry Ford Hospital, we do a huge number of these musculoskeletal ultrasound examinations, and we have had a number of patients come through where we have noticed this relationship between a person's diabetes status and the change in appearance of their deltoid muscle," Rosen said, when explaining why the researchers decided to formally study the phenomenon. "This relationship had been noted for many years at Henry Ford, but by doing this study ourselves, we have adopted this relationship more officially. We believe that we have the correct data now in which we can tell other radiologists to look for this phenomenon as well," she said. "The shoulder joint is often problematic in patients with diabetes, and we tend to see a lot of these patients. "Shoulder pain is frequent in every population, but more so among diabetics, especially rotator cup pathology or so-called 'frozen shoulder,'" Rosen continued. "Quite often, we have done an ultrasound scan on these patients without knowing their diabetic status, and on the basis of what we saw, we asked them if they were diabetic. We have done this multiple times, and as a result, they usually have been diagnosed as diabetic. Anecdotally at Henry Ford, we have seen this happen frequently, and we tell the patients to undergo a diabetic workup, which has resulted in new diabetes diagnoses." Rosen said that with the results of the study, "we now know that we can confidently include this in our reports." She said the brightness signal in the deltoid tissue may be related to adipose infiltration in the muscles, and disordered glycogen or energy storage. "We compared our diabetic patients with obese non-diabetic patients in order to tease out the relationship between the fat infiltration – that is, to see the difference in brightness when the fat infiltration is due to obesity versus when the fat infiltration is due to diabetes," Rosen noted. "By observing the difference in brightness, we could distinguish between those who were diabetic and those who were obese, but not diabetic. Under ultrasound, the difference in brightness between the deltoid muscle and an underlying tendon is flipped when a person has diabetes compared with a non-diabetic patient." All of the studies were performed using ultrasound, and without a contract as part of real-time care. In the retrospective study, the average body mass index for diabetic patients was 34.7, and the average body mass index for obese non-diabetic patients was 34.6. "We presented the ultrasound scans in a blinded fashion to two experienced radiologists who graded the patients on the basis of the images, and concluded whether they were normal, were suspected of having diabetes, or definitely had diabetes," Rosen said. "If the radiologists disagreed, the scan was presented to a third radiologist." When asked for his perspective, RSNA spokesperson Max Wintermark, MD, of Stanford University in California, called the findings "interesting," and added: "There are, of course, many other ways to detect diabetes such as a simple blood draw, but there are some people who don't know that they are diabetic, and they come in for some type of shoulder pain. "And, in those people, the ultrasound finding may actually uncover that they have diabetes without them being previously aware of it," Wintermark told MedPage Today. "So definitely, this is something that radiologists who practice this type of testing should be aware of." Source
