Techniques to improve the imaging of patients who are obese must be employed, researchers say.

According to a WHO report, obesity consumed 2-8 per cent of overall healthcare budgets in 2005 and the condition poses unique challenges to the field of radiology.

Speaking at the European Congress of Radiology in Vienna, Dr Anthony Ryan of Waterford City, Ireland, identified the problems. "Will the patient fit on the imaging equipment, and if they fit, will the images be diagnostic?"

But he said that steps could be taken to overcome these challenges. Vendors are beginning to address the issue, and current MR scanners have a weight limit of up to 550lb in vertical field.

Dr Ryan warned: "The diameter of the MR scanner quoted is the full internal diameter and what it doesn't account for is the table. If you subtract that, you end up with a diameter that's actually up to 15cm less."

Using multiple cassettes in standard radiography might help to ensure that the area of interest is overlying the cassette, he said, and increasing the kVp and mAs could also help. He added: "The most important line on this side is to use a grid - scatter is a huge problem with these patients."

Dr Ryan advised reviewing CT images before the patient is taken off the table, and again to "turn up the power" with an increased kVp.

Touching on nuclear medicine, he said: "The major issue is you're giving a weight-related dose so you could potentially exceed the maximum allowed dose. So if that's the case you just have to give the maximum allowable dose and image for a longer time.

"If patients exceed the weight limit of the table then you might need to image them on the stretcher if you've got a mobile gamma camera."

Also speaking at the meeting, Dr Orla Buckley of Dublin, Ireland added: "We must aim for best practice for these patients. The equipment must be made available so that patients are not denied radiological investigations owing to their size."