Elastography shows promise for rotator cuff tears

By Theresa Pablos, AuntMinnie staff writer

December 4, 2020 -- Ultrasound with a shear-wave elastography (SWE) technique was comparable to MRI for preoperative evaluation of rotator cuff tears, according to a Thursday presentation at the RSNA 2020 virtual meeting. Elastography measurements showed moderate correlation with MR metrics in the 60-patient study.

Assessing muscle quality is critical for planning surgery to repair the supraspinatus muscle in patients with a torn rotator cuff. While MRI has been long used to evaluate rotator cuff muscles, SWE has emerged as a promising new metric that can be performed at the point of care in order to measure muscle elasticity.

"SWE may be useful to predict tendon repairability by evaluating muscle quality," said presenter Dr. Eun Kyung Khil from the radiology department at Hallym University Dongtan Sacred Heart Hospital in Hwaseong, South Korea.

The prospective study compared ultrasound SWE measurements and conventional MRI metrics for predicting whether surgery to repair the supraspinatus muscle would be successful. It included 60 patients with supraspinatus tears who underwent both preoperative MRI and ultrasound scans between May 2019 and August 2020.

One radiologist with five years of musculoskeletal imaging experience performed the ultrasound scans, which the researchers used to calculate the mean elasticity score, median elasticity score, and elasticity ratio.

Elasticity was calculated using a longitudinal ultrasound scan of three regions of interest of the supraspinatus muscle, and the scan was repeated three times in order to have nine total region-of-interest measurements. Meanwhile, the elasticity ratio was calculated by dividing the mean elasticity of the supraspinatus muscle by mean elasticity of the trapezius muscle.

In addition, two radiologists read MRI images, which were acquired with a 3-tesla system. The researchers used the following three standard tools to measure muscle evaluation:

• Goutallier grade system to account for fat-to-muscle ratio
• Occupation ratio of the area of supraspinatus muscle to the supraspinatus fossa
• Warner's muscle atrophy grade

The authors compared the ultrasound and MRI measurements for patients whose surgery was successful, defined as a complete or near-complete repair of the rotator cuff, to patients with an incomplete rotator cuff repair.

MRI and SWE measurements in patients who underwent supraspinatus repair surgery
		Complete repair	Incomplete repair	p-value
MRI	Goutallier grade	1.8	3.78	< 0.001
	Occupation ratio	59.88	31.56	< 0.001
	Muscle atrophy grade	0.39	2.33	< 0.001
SWE	Emean, kPa	31.25	43.84	< 0.001
	Emedian, kPa	29.9	43.54	< 0.001
	Eratio(SST/Tra)	1.84	3.68	< 0.001

Patients with a successful rotator cuff repair surgery had significantly higher scores on both ultrasound and MRI. Both the mean and median elastography measurements were at least 10 kPa higher in the incomplete repair group.

In addition, Khil said the sensitivity and specificity of SWE were high when using a mean elasticity cutoff value of 35.06 kPa and an elasticity ratio cutoff value of 2.61.

Furthermore, the three elastography measurements on ultrasound showed decent correlation with the MRI metrics. The correlation was particularly strong for the elasticity ratio, which had a coefficient agreement of 0.57 with Goutallier grade and 0.66 with muscle atrophy grade on MRI.

"The correlation coefficient was over 0.4, showing a significant moderate correlation, especially in elasticity ratio," Khil said.

The findings were limited by a small number of participants, especially those in the failed repair group. However, it still demonstrated that SWE looks promising for preoperative evaluation of rotator cuff tears.

"In the preoperative evaluation of [supraspinatus] muscle quality using SWE, especially elasticity ratio, showed moderate correlation with existing MR measurements," Khil said.

MRI, U S diagnose post-COVID-19 muscle weakness

By Kate Madden Yee, AuntMinnie.com staff writer

December 1, 2020 -- A combination of MR neurography and ultrasound could help clinicians better diagnose what is causing some recovered COVID-19 patients to continue to experience chronic pain, numbness, or weakness in their hands or limbs, according to commentary published December 1 in Radiology.

The article suggests that combining the two imaging modalities is an effective way to identify nerve damage that results from COVID-19, especially as patients recover and are tracked long-term, lead author Dr. Swati Deshmukh of Northwestern University in Chicago said in a statement released by the university.

"There are physicians out there who are seeing these otherwise young, healthy patients, and they don't know exactly what's wrong and they're thinking, 'What am I supposed to do for patients with post-COVID pain and weakness?' " Deshmukh said. "I want physicians and patients to be aware of the diagnostic options available due to recent innovations in technology and inquire if advanced imaging might be right for them."

As the COVID-19 pandemic has continued, clinicians have observed neuromuscular complications of the illness as those who have recovered participate in rehabilitative care. Imaging is a key tool for evaluating what causes these complications -- from inflammatory neuropathy, to prone positioning-related compression injuries, to nerve entrapment as the result of hematoma, Deshmukh's group noted.

An MR image of a patient in their early 20s shows nerve injury of the left brachial plexus in the neck. The patient experienced left arm weakness and pain after recovering from COVID-19 respiratory illness, which prompted them to see their primary care physician. As a result of the MRI findings, the patient was referred to the COVID-19 neurology clinic for treatment. Image and caption courtesy of Northwestern University.

Determining the cause makes treatment more effective, according to the team. If the cause is due to injury from prone positioning, a patient would be referred for rehabilitation or peripheral nerve surgery. If nerve damage has been caused by inflammatory response, the patient should see a neurologist. And if the damage is caused by hematoma, blood thinner medications should be adjusted and surgery may be necessary, according to the group.

Ultrahigh-resolution ultrasound and MR neurography (which visualizes the peripheral nerves) can localize the problem and assess the severity of nerve damage and whether that damage has affected the muscles, according to the team.

"Peripheral nerve imaging aids diagnosis and may guide management in COVID-19 patients with neuromuscular symptoms arising from the infectious disease, hospitalization course, or secondary to a complication in treatment