Dr Charles Romanowsky
Royal Hallamshire Hospital, Sheffield

Magnetic resonance imaging (MRI) and computed tomography (CT) scans are routinely used in the diagnosis and follow-up treatment of pituitary tumours. A scan is usually the first point of call when a patient is first presented with visual field problems, low or high hormone levels and/or headaches. Scans measure the size and location of tumours and can be used to help decide whether surgery or medical therapy is more appropriate. MRI and CT scans are used after surgery to assess if the entire tumour has been removed or if any residual tumour remains. They are also invaluable in assessing how medical treatment is working.

Dr Romanowski discussed the advantages and disadvantages of CT scans and MRI in detail. CT scans have been used for about 30 years and are very useful for looking at the brain but less so for the Pituitary gland. They involve X-rays (radiation) and one CT scan of the head is equal to approximately 100 chest X-rays. They provide limited anatomical detail as they can only scan one plane of the body. CT scans also require an injection of contrast fluid and there is a risk of an allergic reaction. Advantages include that they take only 2-3 minutes to perform, which is good if the patient is anxious and claustrophobic; they are better for calcification (found with craniopharyngiomas) and can be used for patients of any size. They are also more readily available than MRI.

MRI does not involve X-rays or radiation and can image the pituitary gland and surrounding areas better than CT scans. The injection is less likely to cause an allergic reaction. However, MRI is not as readily available as CT scans. As MRI involves powerful magnetic fields patients must have no metal implants or aneurysm clips (as they may move), so a patient questionnaire must be completed prior to the scan. The scanner is narrower (65 cm in diameter), so limited for larger patients and scans can take 20-30 minutes so patients must lie still for longer. They must lie right in the scanner so MRI is not ideal for anxious or claustrophobic patients. Open MRI scans can be used but the magnetic field is not as powerful so scanner times are longer and are not as detailed as conventional magnets.

Dr Romanowski went on to show various scans, ranging from the most common pituitary problems, i.e. microadenoma (tumours that are less than 1 cm) and empty sella, to the rare problems, i.e. Craniopharyngioma and pituitary metastases.