CT’s fall from grace may lead to spectral redemption

The CT marketplace in the U.S. is teetering on the edge of somnolence, a smoky gray purgatory stirred by a wafting hope of redemption but stalled in melancholy. CT has slipped into this netherworld following the manic adoption of 64-slice scanners, which has saturated the U.S. installed base with CT functionality that can meet all routine-and some extraordinary-clinical needs.

The release of 128-, 256- and 320-slice scanners has elevated CT capabilities, just as multienergy and spectral imaging has raised hopes for new applications beyond the reach of conventional scanners. But because this new generation of premium scanners has found only niche applications, it has failed to ignite the surges in CT adoption that had followed each preceding generation of multislice CTs. Worse yet, their introduction pushed 64-slice scanners into the midtier, creating an abundance of value-priced high-performance systems, weakening demand, softening prices, and undercutting industry revenues.

Last year new unit sales fell to under $800 million in the U.S. from $1.75 billion three years earlier. Results from the first half of this year show continuing erosion, leading some makers of CT equipment to worry that the worst is still to come.

It is not the first time CT has suffered such a fate. The modality surged 20 years ago with the introduction of spiral scanning, which allowed patients to be pitched through CT gantries with greater efficiency than had been possible with the previously standard step-and-shoot methods. But by the mid-90s, spiral scanning had become a commodity much like present-day 64-slice scanners, as the technology had trickled from high-end to midtier portfolios. By the late 1990s, the only differentiator was the computing power built into the consoles of spiral scanners. Then in 1998 quad-slice scanners were released and the market was rejuvenated.

With this, today’s CT community, beset by patient concerns about radiation, falling reimbursements, and anecdotal reports of declining procedure volumes, must ask “what, if anything, can pull us out of this nosedive?” The answer may be right in front of us, as it was a decade ago.

Just as the dual-slice Elscint CT-Twin foreshadowed the multislice revolution, so might the fledgling spectral and multienergy imaging technologies of today foretell the next great surge in CT. Photon counting and triple- and quad-energy systems are emerging along with a new breed of contrast agents as the drivers of spectral CT. From the “energy bins” created using spectral CT may come characterizations of cancer and other diseases, characterizations not possible with conventional multislice CT.

Cardiovascular imaging is the leading candidate for new applications, including the diagnosis of pulmonary embolism and assessment of myocardial perfusion, as spectral imaging is used to characterize and visualize blood vessels, pulmonary emboli, and lumen heavily calcified with plaques or repaired using stents. Already dual-energy CT is showing promise in quantifying plaque burden by distinguishing calcium from iodine media, thereby creating “virtual noncontrast images.” In oncology, spectral imaging might be used to characterize suspicious lesions.

Through such groundbreaking advances, the seeds of CT’s future have begun to take root. And just as dual-slice CT led to the myriad-slice scanners of today, so might the present day dual-energy scanners lead to a still hard to imagine but exciting CT of tomorrow, replete with the kind of market and clinical enthusiasm we saw in the early 1990s and again a decade later.