SWE helps clinicians evaluate Achilles tendon health

By Kate Madden Yee, AuntMinnie.com staff writer

January 17, 2019 -- Ultrasound with a shear-wave elastography (SWE) technique offers an effective way to evaluate Achilles tendon health in both athletes and nonathletes, according to a study published online January 14 in Academic Radiology.

Studies have demonstrated that SWE is useful for evaluating tendon stiffness and can aid radiologists in diagnosing tendinopathy better than other ultrasound modes, as diseased or injured tendons are generally softer than healthy ones, wrote a team led by Dr. Timm Dirrichs of RWTH Aachen University Hospital in Germany. But reference data from varying population groups are lacking.

"[Our main] objective ... was to analyze tendon stiffness in semiprofessional long- and middistance running athletes and to compare [their] tendon stiffness to a nonathletic control group," the group wrote. "[The] second objective was to evaluate the specificity with which SWE was able to predict the absence of clinical symptoms."

Tendons are currently imaged primarily with B-mode ultrasound, power Doppler ultrasound, and MRI. But these methods do not always accurately visualize tendinopathy -- or help clinicians track the transition from asymptomatic to symptomatic disease, according to the researchers.

"In up to 59% of asymptomatic patients, especially athletes, abnormal imaging is present in various tendons, while ... B-mode ultrasound and power Doppler ultrasound might remain inconspicuous in patients with clinical relevant tendinopathy," they noted.

That's where SWE comes in, the researchers wrote. It provides quantitative information about tissue stiffness and, therefore, about the mechanical properties of a tendon, which could be used to estimate tendon integrity.

The study included 68 asymptomatic healthy participants: 33 were semiprofessional athletes who completed at least five training sessions of running per week, and 35 were nonathletic individuals. Each participant's Achilles tendons were imaged with B-mode ultrasound, power Doppler ultrasound, and SWE (136 tendons). SWE values were expressed in kilopascals (kPa).

The mean SWE value for the Achilles tendon was 183.8 kPa in athletes and 103.6 kPa in nonathletes, a difference that was statistically significant (p < 0.001).

"We found athletes' Achilles tendons to be 1.8 times as hard as nonathletes' tendons obtained by SWE," the group noted. "This phenomenon may be caused by repeated training effects."

The researchers found that SWE outperformed both B-mode and power Doppler ultrasound in terms of the specificity of classifying an asymptomatic tendon as healthy:

• B-mode ultrasound: 60.6%
• Power Doppler ultrasound: 93.9%
• SWE: 96.3%

SWE is useful for measuring and displaying the effects of training on the Achilles tendons of athletes, and its high specificity could help clinicians better care for patients, the group wrote.

"[SWE] ... has a high specificity to predict absence of clinical symptoms," Dirrichs and colleagues concluded. "This might be of great clinical interest, especially in asymptomatic athletes, where the rate of false-positive findings in conventional B-mode ultrasound and power Doppler ultrasound is high."

Can prenatal ultrasound predict Zika infection outcomes?

By Kate Madden Yee, AuntMinnie.com staff writer

January 8, 2019 -- Abnormal results on prenatal ultrasound scans in women infected with the Zika virus may help predict how the virus will affect the fetus after birth -- but they can't be considered definitive, according to a study published online December 28 in JAMA Network Open.

Yes, ultrasound can identify the potential for adverse outcomes in fetuses exposed to the virus, but it's not the be-all and end-all solution because many babies with normal prenatal ultrasound findings are born with complications from Zika, wrote a team led by Dr. Jose Paulo Pereira Jr. of the Instituto Nacional de Saúde da Mulher, da Criança e do Adolescente in Rio de Janeiro.

"More than half of the patients [in our study] with abnormal results on neonatal examinations had no structural findings on prenatal ultrasonography. ... Our results suggest that prenatal ultrasonography may have a limited ability to provide reassurance of a normal neonatal outcome in maternal Zika virus infection," the authors wrote.

Literature on whether prenatal ultrasound can help determine how babies will be affected by the Zika virus has mostly included cohorts of babies identified pre- or postnatally with microcephaly. But Zika can cause other complications in the central nervous system, such as calcifications, ventriculomegaly, cerebellar vermis hypoplasia, and agenesis of the corpus callosum, according to the investigators.

Pereira's team sought to investigate the association between prenatal ultrasound findings and newborn outcomes among pregnant women infected with the virus. The study included 92 mother-baby pairs; the median gestational age of the babies at delivery was 38.6 weeks. Abnormal findings included a range of central nervous system irregularities, as well as other conditions such as fetal growth restriction, arthrogryposis, fluid abnormalities, placentomegaly, and macrosomia.

Of the 92 mother-baby pairs, 55 (60%) had normal results on prenatal ultrasound and 37 (40%) had abnormal results. Of the 55 pairs with normal results, 23 newborns had an adverse outcome (42%); of the 37 pairs with abnormal results, one fetus died at 36 weeks, and 21 of the remaining 36 had an abnormal outcome (58%).

"We found that major Zika virus-associated abnormalities observed on prenatal ultrasonography were associated with a sixfold to 27-fold increase in the odds of composite adverse neonatal outcomes of abnormal results on neonatal examination or postnatal neuroimaging," the authors wrote. They defined composite adverse neonatal outcomes as perinatal death, an abnormal finding on newborn exam, or an abnormal finding on postbirth neuroimaging.

Association between ultrasound findings and adverse birth outcomes
Ultrasound result	Neonatal exam	Postnatal neuroimaging	Composite neonatal outcome
Zika virus-associated abnormal finding
Normal result	3.9%	4.4%	2.1%
Abnormal result	22%	30.4%	22.2%
Adjusted odds ratio	11.6	6.7	27.2
Central nervous system abnormality
Normal result	3.9%	2.2%	2.1%
Abnormal result	19.5%	30.4%	20%
Adjusted odds ratio	11	13.9	27.2

An abnormal result of any type on prenatal ultrasound had a sensitivity of 48.9% and a specificity of 68.1%. For a major abnormal result that was specifically associated with Zika, sensitivity was 22.2%, specificity was 97.9%, positive predictive value was 90.9%, and negative predictive value was 56.8%.

The study shows that more research is necessary, according to Pereira and colleagues.

"In the setting of confirmed Zika virus infection in pregnancy, prenatal ultrasonography is a useful tool for anticipating an association with adverse neonatal outcomes, but its negative predictive value ... is low," they concluded.