EchoSens creates non-invasive liver diagnosis medical devices. The company’s line of products, called FibroScan, work by measuring the speed of ultrasound waves as they move through liver tissue. This measurement can tell us about the state of the liver. For example, ultrasound waves move faster through fibrotic/scarred livers. EchoSens recently appointed Dominique Legros as their new global CEO, and we recently spoke about his plans for growth in a Medgadget exclusive.
To learn more about how a clinician would use the FibroScan, we spoke with Dr. Stephen A. Harrison, Medical Director of Pinnacle Clinical Research and Visiting Professor of Hepatology at the University of Oxford.
Ben Ouyang, Medgadget: Tell me about yourself.
Dr. Steven Harrison: I’m a gastroenterologist and hepatologist who has spent the past 15 years focusing my research efforts on non-alcoholic fatty liver disease. In particular I’ve focused on epidemiology, non-invasive testing, and therapeutic modalities to treat the disease. I have worked closely with Echosens over the past several years, developing their non-invasive ultrasound-based shear wave elastography modality FibroScan to identify patients with fatty livers through the use of a Controlled Attenuation Parameter (CAP), and assess the stiffness using their kilopascal technology (kPa). Ultimately, I’m helping to identify patients who do not have disease and identifying patients that are at risk of having liver disease.
Medgadget: What’s the current state of fatty liver disease?
Dr. Harrison: We’re living in an epidemic. Non-alcoholic fatty liver disease (NAFLD) is really linked very closely and very tightly to obesity in insulin resistance and diabetes mellitus. Both of those conditions are increasing both in incidence and prevalence throughout the world. We’ve seen a rise in the incidence in prevalence of both NAFLD and its more severe form of fatty liver called non-alcoholic steatohepatitis (NASH). That’s a big fancy word, but ultimately, steatohepatitis means “inflamed fatty liver”. We distinguish this from alcoholic liver disease by taking the patients that drink fewer than two drinks a day on average (female), and fewer than three drinks a day on average (male).
Medgadget: What’s the magnitude of NAFLD and NASH?
Dr. Harrison: We can look at a recent perspective prevalence study that Echosens helped me work on, conducted right here in San Antonio, Texas. We found the overall prevalence of NAFLD to be 37%. That’s almost more than one in three people over or at the age of 55 having fatty liver. Some estimates go as far as 100 million Americans. The prevalence is of NASH is 15%. So this is not a rare disease and this is by all accounts a major problem for us.
Medgadget: How is NASH diagnosed? How is NAFLD diagnosed?
Dr. Harrison: Diagnosing NASH still requires a liver biopsy. Unfortunately, we haven’t developed our non invasive testing quite good enough yet to make that distinction between a little fat in the liver, versus NASH, where fat is inflamed and irritated and leading to scar tissue associated with it.
Non alcoholic fatty liver disease can be diagnosed several different ways. First of all, we take a patient’s history and first exclude the alcohol. Secondly, we have to exclude medicines that cause fatty liver which would be the classic ones: methotrexate, amiodarone, valproic acid, steroids and tamoxifen. Then after that, we get an imaging study, whether that’s an ultrasound, a CT, an, MRI or a FibroScan.
Medgadget: How does FibroScan tie into your clinical workflow?
Dr. Harrison: I use it like what I would call a “sixth vital sign”. We need a test that’s quick, easy to use, non invasive, and has a high negative predictive value. What I want to do is exclude people that don’t have disease that I would need to worry about as a liver doctor. So before I see the patient, I have one of my techs do a FibroScan. If they have fat in their liver, then I quantify that or at least say yes or no. And then I get the liver stiffness.
FibroScan guides me to say: “Is it fat or is it not fat?” If it’s fat, now I need to ask my patient about alcohol. If there’s no or minimal alcohol, now I’m focused on NAFLD. And if it’s NAFLD, I need to focus on metabolic syndrome, so: does the patient have diabetes, hypertension, hyperlipidemia, obesity? Let’s say they do and the kPa [stiffness] is low – then let’s talk about lifestyle. If the kPa is high, let’s consider referral or liver biopsy. Now if it’s not a fatty liver, that takes me down a whole new track, which includes drug induced liver injury, viral hepatitis, autoimmune hepatitis, cholestatic liver disease, iron overload, alpha-1 antitrypsin deficiency, copper overload – that sort of thing.
Medgadget: How does the liver stiffness measurement influence your management?
Dr. Harrison: What I use in clinical practices is that if their liver stiffness score is 6 or less, I tell them: “You have fat in your liver, but it’s not doing any damage to your liver.” So that changes my discussion with the patient to one now that becomes advice to modify lifestyle: “eat less, run more”. Now if the stiffness score is above 8.5 and they have fat in the liver, now I’m saying to them: “Well, you might have a problem, we need to do more work”. And that’s where we move on to MRI plus or minus liver biopsy to determine their risk for NASH with fibrosis.
Medgadget: How many of your patients does the FibroScan work for?
Dr. Harrison: I could call it my 80% solution, because it’s really good at excluding the 75 or 80% of people that aren’t going to have NASH that I need to worry about.
Medgadget: What’s the limitation on the other 20%?
Dr. Harrison: While it is a very effective tool, there are some caveats that need to be considered. Patients need to be fasting for ideally three hours prior to the test. It’s also not a very effective tool in the setting of ascites: so if you have fluid in your belly, that’s not going to allow us to get a good reading. And if you have a pacemaker, they don’t recommend doing the FibroScan. Then I would say also in morbidly obese patients it can be challenging to get an accurate reading because if you have several centimeters of subcutaneous fat that you’re unable to compress, then your probe will begin reading this fat prior to getting to the liver.
The major caveat that I would say that clinicians need to be really clear about is this test is not ideal at predicting stages of fibrosis. So sometimes my colleagues will make mistakes and say, “okay, CAP is 380 and clearly that’s fatty liver”. I agree with that because anything above 280 is fatty liver. But then they’ll see kPa at 10.5, and they’ll say “Oh my gosh, this patient has advanced liver disease”. Then they tell their patients, and that’s where it falls apart. That diagnosis requires a biopsy to make. If the kPa is between is between 8.5 and 13, and the cap is higher than 280, I instead say: “likely fatty liver and possible moderate to severe scarring; follow up for further evaluation. Consider participation in a clinical trial for fatty liver disease.” If they don’t have access to clinical trial, I would say consider liver biopsy.
Medgadget: How might other clinicians use FibroScan in their workflow?
Dr. Harrison: We use it in a couple of different ways. I use it in my clinical practice to help set the stage for my conversation with the patient. Before I go in the room to see the patient, I know “do they have fat? Do they not have fat? Is there scarring?” It changes my conversation depending on what I see. Now, as a primary care doc or an endocrinologist, I would use it in the same vein, but then I would use it to determine which patient needs to be referred to a GI doc or liver doc.
There’s also a portable unit that’s the size of a large laptop that you can take with you. I use that in a novel way: I take that into primary care clinics and independent clinics and I do the scanning for them, and then I share the results on their patients. I guide them to say this is a patient that you don’t need to refer or this is what I would consider referring for further work.
Product info page: FibroScan…