Converter Boosts MRI Image Quality

A new digital-to-analog converter (DAC) promises to providebetter image quality for magnetic resonance imagers (MRIs), enabling radiologiststo detect illnesses earlier.

Engineersat Analog Devices Inc., maker of the newDAC, believe its combination of high accuracy and low-noise performance couldhelp reduce the number of "artifacts" in images and thereby lessen the need formultiple MRI scans for patients. ADI says the device could have a profoundeffect on MRI procedures, which are now done approximately 60 million times peryear worldwide.

"Radiologistsare looking for clearer images to diagnose illnesses at an earlier stage," saysBrendan Cronin, product marketing manager for precision data converters at ADI."This product enables clearer and faster scans to be performed, which leads tobetter diagnostic outcomes."

Known asthe AD5791DAC, the device reportedly offers 1-ppm performance, with four times betteraccuracy, four times more resolution and 30 percent less noise than existingDACs.

"Veryoften, there's a tradeoff between accuracy, resolution and noise," Cronin says."You use bigger resistors to get better accuracy, but that leads to highernoise. This product balances both and achieves very low noise levels withhigher resolution and better accuracy."

ADIengineers say the AD5791 incorporates approximately 10 discrete components -including amplifiers, field effect transistors (FETs), resistors and otherconverters - into a single form factor measuring 4.4 x 6.5 mm. The companyclaims that the device could help reduce an MRI's electronic package size andcut time from the design process.

"Previously,the smart MRI engineers could make low-ppm systems, but they would have done itwith a heap of discrete components, including as many as 10 or 15 converters,"Cronin says. "This eliminates the headache of using all those discretecomponents by providing a single-chip solution."

ADI says theAD5791's combination of accuracy and low noise also make it a candidate fortest and measurement systems, high-end aerospace instrumentation, communicationequipment and industrial control systems.