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ULTRASOUND TECHNOLOGY ALLOWS US TO ACCURATELY STAGE FATTY LIVER DISEASE

Ultrasound has been a godsend for medicine. We can take a deep look into the inner workings of organs and systems, while at the same time, not breaking the bank. We rely on ultrasound for prenatal ultrasound because through intense scientific studies and investigations it has been proven to be the safest method. Recently, there has been a boom in ultrasound technology paving the way for methods like Fibroscan, acoustic radiation force impulse imaging (ARFI) and acoustic structure quantification (ASQ). Lucky for us, science is an ever-evolving giant and now, with its help, we may soon be able to stage liver steatosis (fatty liver disease) accurately, and most importantly, noninvasively.

Why hasn’t this been thought of before?

Ultrasound is capable of visualizing many diseases of the liver, steatosis being one of them. But the main distinction here, is that before advancements made by scientists from Radboud University Medical Center in Nijmegen, the Netherlands, we were unable to accurately stage and diagnose fatty liver disease with ultrasound. Through their painstaking work, they were able to perfect a computer-aided technique that can run on almost any ultrasound machine.

Although the group specifically studied patients on home parenteral nutrition (infusing food through a vein), that are particularly susceptible to steatosis, their results are far-reaching. They compared their software’s performance to MR spectroscopy measurements and the study proved similar performance between the two methods, which is incredibly promising.

"By simply using a calibrated ultrasound machine and our software, a noninvasive, easily applicable method for staging liver steatosis is obtained, which might in the future prevent biopsies," lead author, Gert Weijers said.

The road to progress is arduous

Liver steatosis is an accumulation of fat in the liver which is usually cause by alcohol consumption, obesity, and other metabolic disorders. It’s important to know that this disease is reversible if lifestyle changes are made in time. Patients on parenteral nutrition can develop liver dysfunction and subsequently, liver fibrosis, cirrhosis and everything in between.

Like other famous inventions and advancements made in medicine, researchers stumbled upon the possible use of computer-aided ultrasound for assessing liver steatosis. They initially developed the software for veterinary use for cows, who are often plagued by fatty livers. Before even testing it on animals, they had to use phantoms to calibrate the system.

The software figures out and compensates for the depth dependence of the ultrasound beam and attenuation from superficial tissues. It then automatically picks out a region of interest and comes up with a number (in decibels per centimeter). This quantitative measurement shows what the signal attenuation is, compared to normal liver images. If the attenuation is higher, then the fat concentration is higher.

How it compares to MR spectroscopy

After the initial animal testing, the researchers set their sights on confirming the software’s possible use in humans. To find the true worth of a diagnostic method, it has to be compared to existing, accepted methods. MR spectroscopy (MRS) is an accepted method that gives is quantitative information on fat content. When the study authors put their results up against MRS, they were delighted to find strong correlation across the board, especially in the residual attenuation coefficient. What we get from this is the simple fact that this yet unnamed method has high specificity and sensitivity for quantitatively evaluating liver steatosis.

There’s still so much to be discovered

The study on parenteral patients was performed using ultrasound scanner PHILIPS Sonos 7500 with a 3- to 8-MHz phased-array transducer. This shows what’s really great about this nifty tool – it can be used on any ultrasound system with digital DICOM output. With the advent of this computer-aided ultrasound method we may be able to screen for steatosis for early diagnosis and treatment.  

By Dr. Yuriy Sarkisov, BiMedis staff writer

04.05.2016

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