Heart set on screening

A portable device designed to measure the heart’s magnetic fluctuations is set to enhance screening for a number of cardiac conditions and dramatically improve diagnosis.

The device — a magnetometer — is being developed at Leeds University through an Engineering and Physical Sciences Research Council-sponsored project.

Lead researcher Ben Varcoe, of the university’s Quantum Information Group, said that the device can detect problems with the heart faster than diagnostic techniques such as ultrasound and ECG.

While cardiac magnetometers are widely available, their size and cost, and the associated skills needed to operate them have prevented them being widely used to identify heart conditions.

Varcoe said that heart screening with cardiac magnetometers requires a patient to be contained within a magnetic shield to cut out other electrical interference. It also takes up a significant amount of hospital space, he added, because the devices and their associated sensors need to be cooled down with large refrigerators that maintain almost absolute-zero temperatures using expensive cryogens.

The new system overcomes these difficulties by placing the detector in its own magnetic shield. Varcoe said that, unlike usual magnetometers, the role of sensing and detecting in his device is essentially carried out in two different operations.

’The traditional thinking was the detector and sensor had to be the same thing,’ he added. ’We have separated the two roles, so we have a sensor head that picks up a field and transmits that back to the detector.’ The sensor head, which is placed over the area being examined, consists of coils that cancel out unwanted signals and amplify the required ones. These signals, which originate from the tiny magnetic fields generated by the heart, are transferred to the shielded detector.

According to Varcoe, the system then produces a moving image of the heart’s magnetic signature. The changes in the magnetic field are represented by various overlapping colours that would appear like a blurry infrared image to a laymen. A trained medical practitioner, he said, would be able to distinguish whether there is presence of certain cardiac conditions, such as arrhythmia.

’Arrhythmia often produces littleloops of current that would show up as a hot spot in the scan,’ he said. His team is now working on miniaturising the magnetometer. A device could be ready for use in routine diagnosis in three years.