How do radiologist make diagnosis and why they take history?

Radiology is a science and possible diagnosis given by a radiologist is evidence based. 

The conclusion radiologist makes are based on:

1. Patients symptoms eg. Pain in abdomen
2. Chronology: eg. Headaches since few years or sudden and worst headache of my life. 
3. Clinical signs: eg. Doctor felt a lump in the abdomen on palpation (examination). 

      4. Laboratory findings: eg. Bugs grown on urine culture or occult blood in the stool

       5. Past history, previous medical treatments and surgical procedure: eg. Gallbladder removed in   the past or had kidney stone few years back. 

6. Observations based on the imaging done like X-Ray or CT Scan.

Many people may believe, radiological tests are as good as X-Ray scanning machines at the airport. By the time the test is over and patient comes out of the exam room, results will be already ready. Reality…………? This is far from the truth.  Majority of diseases and patients do not have classical presentations. There is nothing in black and white. This is where radiologist’s experience, examination, and history can be extremely useful. 

Radiological interpretation is highly depend on clinical information. Without relevant clinical information correct interpretation may not be possible. It is like flying a plane without co-ordinates! A classic example would be “blood in urine”. Most commonly this happens due to a kidney stone or urinary infection. But similar presentation could be in a patient with cancer of kidney. In stone disease it is usually accompanied with pain and radiologist demonstrating the actual stone on imaging; whereas, in a cancer, it may be quite often without pain and radiologist will demonstrate the tumor and its location.

Key in medicine is differentiating between a normal variant and pathology. This difference at times may be subtle and difficult, but this where the clinical skills and experience comes in handy. It is possible that the radiologist may not come to any conclusion based on that one test. In that case a follow up or a new test may be required.

The next time you visit a radiology clinic, help your radiologist by providing as much history and  other relevant documents pertaining to laboratory test, previous radiological exam, past illness and medical/surgical treatment taken. We are likely to give better outcome and useful report for you.

References:

http://www.kevinmd.com/blog/2012/05/radiologist-provide-history.html
http://quizlet.com/6671734/radl52-ch-12-history-taking-flash-cards/original