Radiological Output

Radiological investigations that I deal with can give information of the followings:

1. Space occupying lesion (SOL) - presence of a lesion which is 'new' or 'extra' and occupies the area that supposedly belongs to the native organ. E.g. a kidney cyst is an SOL. A kidney cancer is also an SOL. Distinction of a fluid or non-fluid lesion is delicately handled by ultrasound.
2. Alteration or distortion of normal architecture / anatomy - the anterior cruciate ligament is supposed to have an angle similar to the roof of the intercondylar notch. If it is more horizontal than the angle of the roof, ruptured ligament has to be considered.
3. Replacement of normal tissue - e.g. in stroke, the normal brain tissue is replaced with oedematous, dead brain tissue, rendering the abnormal area to be delineated from the normal tissue. On CT scan, infarcted brain is hypodense (low attenuated) while on MRI (T2WI), infarcts are hyperintense (bright signal).
4. Presence of foreign object - swallowed coin in the intestine. Metallic fragment in the muscles.
5. Artifacts - troublesome but cannot be avoided. Sometimes due to the dense skull structures in the base of the skull, beam hardening artifacts are present causing the brainstem to be less well visualized. A solution is to rescan with MRI which does not face problem with the dense basal skull bones.

Having said that, a radiologists often cannot tell conclusively of the true nature of the lesion. Radiologists are clues hunte. In a case of a suspicious tumour, looking for concomitant presence of lymph nodes enlargement, ascites and distant disease, which if all are present, will suggest a malignant process. I think patients often have better understanding when I explained that radiologists can confidently tell that there is abnormality involving certain organs but cannot 100% confirm the true nature other than having the surgeon remove the lesion, put the lesion under microscope and establish the histopathological diagnosis.

The exception is in functional imaging, e.g. PET-CT, nuclear medicine scans and DEXA where quantitative data can be obtained.