VIIRadiol Bras. 2010 Nov/Dez;43(6):VII-VIII
EditorialThe diagnosis of diffuse liver disease, including characterization and quantification, has gained particular importance in recent years, reflecting in large measure advances in imaging techniques. During the same time period concern has escalated about the use of CT due to the harmful effects of radiation. The net result is that the non-invasive techniques of sonography and magnetic resonance imaging (MRI) have achieved considerable interest.Both methods are non-invasive, innocuous and safe, but with important and noticeable differences. While sonography is a well established and widely used method, reflecting its low cost and portability, it suffers with high operator dependence variations, low sensitivity and even lower specificity. On the other hand, MRI is a comprehensive method with multiple types of data acquisition, and unmatched ability to differentiate normal from diseased tissues. The drawbacks of MRI are less availability, no portability, and higher cost.Despite these limitations and others discussed below, both methods are progressively replacing more invasive diagnostic techniques. Portal system morphology and hemodynamics constitute suitable application areas for both Doppler sonography (DUS) and MR techniques. Clinical indications for hepatic venous pressure gradient measurements performed by angiography are: prediction of clinical events, sequential assessment of clinical evolution, assessment of pharmacologic therapy, and assessment of pre- operative risk in cirrhotic patients (1) . Because of the invasiveness of the procedure and that it is unlikely to achieve more widespread use, this direct measurement technique is likely to be confined to basic research studies and not develop substantially into clinical utilization.In this issue of Radiologia Brasileira Leão et al.( 2) have written an interesting article testing interobserver reproducibility of DUS and MRI for the evaluation of portal blood flow in schistosomal patients (2) . An intriguing finding is the poor intermethod agreement between these two methods. It is always refreshing when authors in the scientific literature provide sobering prudent observations, rather than the usual over enthusiastic description.The sonography evaluation of the portal system is probably adequate for the majority of patients. One major exception being the overly obese patients, as there is often the lack of appropriate sonographic window, and often, as a result, or due to coexistent fatty liver, which complicates visualization because of heterogeneous echotexture. With this caveat in mind, DUS can adequately diagnose hepatic schistosomiasis, characterize the portal vein flow, and display portal hypertension related findings, i.e., splenomegaly, ascites and varices. However, the challenge to identify patients at risk for upper gastrointestinal tract bleeding remains, and this has been the subject of other studies (3,4) . Compared to DUS, MRI is a much more comprehensive imaging method to evaluate the abdomen...
