英国伯明翰大学医学院肝脏研究中心Philip Newsome博士
Hepatology Digest: Controlled attenuation parameter (CAP) meets what clinical needs?
Dr Newsome: CAP is a useful development in that it allows us to measure the level of fat inside the liver more accurately than before and at lower levels than before. In that sense, the functions of CAP can probably be thought of in two ways. One is to try and identify levels of fat in patients but more importantly I think allowing us to assess changes in liver fat in response to treatment or in response to progression of liver disease.
Hepatology Digest: What factors affect the application of CAP? How can we avoid and reduce these factors when we use CAP?
Dr Newsome: In most patients where you are thinking of using CAP you are dealing with patients who have fatty liver disease and many of those patients will have elevated body mass indices and will be overweight. In those patients, using the M probe is problematic so one needs to use the XL probe. At the moment, the XL probe doesn’t have the CAP facility but that is a work in progress. So at the moment, a large number of patients about whom you want to know about, cannot be studied with CAP functionality. We know that fasting status, for example, is important in terms of determining levels of hepatic fat so having patients fasted or performing the CAP analysis at the same time of day will be important to ensure that one reading can be extrapolated to follow-on readings.
Hepatology Digest: Can you introduce the relationship between the accuracy of CAP and fat content?
Dr Newsome: There have been several studies that have looked at CAP and the ability to quantify levels of fat inside the liver. There is a very good correlation between CAP levels and fat readings by biopsy. I think the association between those readings is best when trying to categorize high levels of fat and low fat and for that I think it performs very well. Where it becomes more problematic is trying to tease out differences between different levels of steatosis. So rather than saying presence of fat and absence of fat, trying to distinguish between levels of fat such as S3 or S2 is where CAP is more problematic.
