Jog wheel turns heads and wrists

A gadget similar to one popular among video editors is earning radiologists' approval for the navigation of large multislice CT data sets, according to a study published in the February issue of Radiology.

Anthony J. Sherbondy and colleagues at Stanford University analyzed the navigation of large CT angiography data sets acquired with an eight-slice CT scanner from patients with peripheral vascular disease, aortic dissection, and abdominal aortic aneurysms.

Five radiologists with CTA experience were asked to find 25 clinically relevant targets - previously chosen by a cardiovascular imaging expert - for vascular disease diagnosis. The researchers gauged the radiologists' efficiency and accuracy in accomplishing this task using five different navigation tools:

• jog-shuttle wheel

• mouse

• tablet and stylus divided into two independent mapping control devices

• trackball

The jog-shuttle wheel ranked highest in terms of speed and comfort, while the trackball scored the lowest.

Several other studies bear out Sherbondy's findings. In one presented at the 2003 RSNA meeting, Ohio researchers led by Dr. Thorsten R. Fleiter, now a radiologist at the University of Maryland, compared several input devices to detect lung nodules. The jog wheel scored highest in terms of preference and comfort and the lowest in terms of potential fatigue.

Preliminary findings on a trauma MSCT study by Fleiter to be published soon suggest that, when confronted with the choice between the jog-shuttle wheel and a mouse, radiologists prefer the former. Meanwhile, they score no statistically significant differences with either device for detection of fractures.

The implementation of PACS might have inadvertently aggravated ergonomic issues, Sherbondy said. PACS vendors usually offer their workstations with either a standard trackball or a three-button mouse for control on increasingly sophisticated CT and MR image navigation systems. Researchers have documented radiologists' complaints about wrist, forearm, and hand soreness attributed to these devices.

Although several factors beyond utility and ergonomics determine whether a particular device will catch on, radiologists and clinicians should demand that PACS workstation vendors consider including devices like the jog-shuttle wheel. Their qualitative advantages seem clear when measured against the common trackball and mouse devices, Sherbondy said.

The implementation of input devices that make for a better fit to MSCT data set navigation may reduce repetitive injuries incurred by radiologists and clinicians, he said.

For more information from the Diagnostic Imaging archives:

PACS reading protocols tame information overload

CT slices yield to 'computerized volumetric imaging'

True 3D moves into practice

3D challenges radiology