With a widening array of CT scanner options, purchasers need to be aware of what each manufacturer offers and avoid some common sources of confusion, according to an Oct. 17 web conference presented by the ECRI Institute.

It’s important to understand the type of technology being purchased, particularly because there’s a factor of four difference from a low-end 16 channel scanner to the latest premium technology, explained Jason Launders, senior project officer and medical physicist for the ECRI Institute. “It makes a lot of sense to choose what really meets your need,” he said. “We believe that a lot of people probably over-buy technology, but we also know there are [many] considerations.”

The number of slices a scanner offers has become a source of confusion, according to Launders. Counting slices is no longer sufficient, as purchasers must also consider total coverage, detector rows, data channels and advanced technology. “Over the last three or four years, slices have become less important as other technology within the CT scanner has become more important.”

Manufacturers can double channels to increase slices, Launders explained. For example, a scanner can have 64 detector rows, but acquire 128 slices using double sampling, which provides sharper images. He added this only provides advantages if a study calls for thinner slices to begin with, which many routine studies do not require.

Looking past the number of slices is especially important when considering high-end premium systems, as they will have more unique offerings with regard to dose reduction and other advanced technologies. Additionally, the type of studies that will be performed on the scanner plays a key role. Rotation time, for instance, is generally only a significant issue with cardiac studies.

ECRI member survey information has shown a declining interest in 64 channel systems, which garnered the most relative interest as recently as Q4 2011. They have given way to increasing interest among purchasers for 128 slice scanners and more advanced premium systems.

Launders closed his presentation with by summarizing the advantages and disadvantages of the different classes of CT scanners, including:

- 16 Channel: These scanners can perform all routine studies at a low cost, However, they represent the lower end of scanner technology, and don’t support advanced studies. These systems are the last to get dose reduction technology upgrades. Larger patients are not well accommodated.

- 20 to 40 Channel: This next step up in CT scanner class opens the door to some upgrade options at a modest cost. They are still limited with regard to the types of advanced studies they can perform and don’t support cardiac imaging.

- 64 Channel: Launders described this class of scanners as the workhorse in CT imaging over the last six or seven years. These middle-of-the-road scanners perform all routine and some advanced studies, and offer many upgrade options, though they still lag behind higher class scanners for advanced studies.

- 128 Slice: These scanners include all options, better artifact reduction and many dose reduction features, though these advantages mean a higher cost and a steeper learning curve for users.

- Premium: This class encompasses a wide array of the latest scanners offering the very latest in technology and dose reduction. Here again, Launders cited high costs and more required training as a disadvantage, and noted some of the latest features may not yet be well established.