The National Health Service (NHS) has supsended a five-year contract for IT services firm Atos Origin to supply diagnostic scanning pending a review after 900 patients had to be recalled due to technical problems.

Atos has been running a pilot MRI and ultrasound scanning service in the north west of England since December. The service was set to be expanded this month, to include DEXA bone density and Computerised Tomography (CT) scanning in a five-year deal.

But the contract, negotiated through the Department of Health (DoH), is now under review after 900 patients referred for ultrasound scans had to be recalled for rescanning following an audit that revealed administrative and technical problems with the scans.

The DoH had been expecting Atos to provide an additional 230,000 scans a year to clear bottlenecks in diagnostic testing and help meet government waiting time targets.

A statement from the NHS North West said concerns had been raised about the service in mid-February when a clinical audit found that some patient information was not being correctly recorded and that better quality images could be obtained by using higher specification equipment.

A separate review of the MRI scanning service found delays in passing diagnostic information to referring GPs. A decision was then taken to suspend the service while a review is carried out.

Mike Farrar, chief executive of NHS North West, said: "Starting the service early in a limited way has helped flush out these operational issues. We are being vigilant and cautious, but we want to assure ourselves and the public that the additional services we are commissioning on their behalf are safe and of the highest quality."

A spokesperson for the IT services firm said: "Atos Origin, in consultation with the Department of Health and the NHS, has taken the decision to stop accepting referrals for all diagnostic examinations while a full process review takes place. The three parties continue to work together in preparation for service delivery scheduled to commence in the coming months."