Overview

Knowledge gaps, Background and Foreground knowledge

Imagine a 1st year resident sitting in with a staff radiologist for an abdominal CT reporting session. The case in question is one in which a focal liver lesion, incidentally diagnosed in a young adult female, is being further investigated. The most likely diagnosis is focal nodular hyperplasia (FNH). The ‘knowledge gaps’ of the first year resident and the staff radiologist will be very different. The resident will need ‘background’ knowledge about abdominal anatomy, CT technique, pathology and appearances of FNH and other lesions. The staff radiologist will (probably) know enough to interpret the case, but may have other ‘foreground’ knowledge needs. For example, he/she may consider the lesion is probably FNH but want to suggest another test. He/she may have heard, at a refresher course, that triphasic hepatic CT was less specific than enhanced hepatic MRI for the diagnosis of FNH and may want to choose between SPIO and Gd-BOPTA for this indication.

The resident has questions about ‘background’ knowledge. The staff radiologist has questions about ‘foreground’ knowledge. As we proceed in training and specialisation, our need for background knowledge decreases. The further we get from our ‘graduation’ – be it Boards or Fellowship, the need for ‘foreground’ knowledge increases. Clearly the distinction is never absolute ‘We are never too green to learn foreground knowledge, nor too experienced to outlive the need for background knowledge.’ [2]. Traditionally, we rely on local ‘expert opinion’, journal scanning and CME meetings to fill these ‘knowledge gaps.’ These measures can be usefully supplemented (and sometimes superseded!) by ‘Evidence-Based’ methods that use modern informatics to bring reliable, up-to-date information to the point of care.

Textbooks are usually a few years behind the ‘cutting edge’ and can rapidly go out of date. This is a major problem in Internal Medicine. It may be less of a problem in certain ‘stable’ aspects of radiology – take, for example, Morton Meyers’ description of ‘Intraperitoneal Spread of Malignancies’ [3]. Regardless of interval changes in therapeutic protocols, the description remains valid. This is because, once radiologic-pathologic correlation has been well worked out for a particular disease and imaging application, the knowledge base should remain applicable over time. On the other hand, we lack a transparent, reproducible process for appraisal of ‘radiologic-pathologic’ studies and the rapid pace of technology development makes up-to-date knowledge essential for modern radiologists.

In Diagnostic Radiology, therefore, the main ‘foreground’ questions EBR can address are related to the superiority of one imaging method over another in resolving clinical dilemmas and the power of imaging signs to reliably confirm or exclude suspected disease processes. In interventional radiology, the main ‘foreground’ questions are related to the short, medium and long-term benefit / harm of new interventional techniques compared with older interventional methods or more invasive surgical procedures. We will approach ‘The Answerable Question’ for Diagnostic and Interventional Radiology in this context. To get the best out of the site, bring along a question from your own practice.

References

1. Sackett DL, Richardson WS, Rosenberg W ,Haynes RB, Evidence Based Medicine, How to Practice and Teach EBM. 2nd Ed, 2000, Edinburgh: Churchill Livingstone. [ link ]

2. Sackett DL, Strauss SE, Richardson WS, Rosenberg W ,Haynes RB, Introduction, in Evidence Based Medicine; How to Practice and Teach EBM. 2000, Churchill Livingstone: Edinburgh. p. 1-4. [ link ]