Spectral CT: It Pays to Weigh the Costs and Benefits

Since the first commercial dual-energy computed tomography (CT) scanners made their debut more than 20 years ago, there have been ongoing advances in this technology. The latest improvement is the Philips Spectral CT 7500. Its unique dual-layer Spectral detector takes dual energy to the next level, allowing for “always-on” spectral results regardless of patient type. This allows for all the benefits of multi-energy CT without any of the drawbacks of traditional dual-energy systems, making a compelling case for adding this system to a healthcare facility.

As with any significant acquisition of new technology, it pays for facilities to perform a cost-benefit analysis to ensure such an investment makes sense, from both financial and clinical perspectives.

Clinical benefits of implementing Spectral CT

Spectral CT has many advantages over conventional CT, including the availability of an iodine decomposition map, said Aran Toshav, MD, adjunct clinical associate professor of radiology at Louisiana State University in New Orleans.  “For me, the most important thing is the iodine decomposition map because it tells me where iodine is displayed using the two spectral/photon energy points,” Dr. Toshav explained, citing the example of a patient with renal cancer being treated with an inhibitor. In this case, the spectral CT iodine decomposition map revealed the lack of enhancement in portions of the renal mass, while conventional CT images did not.

“There’s some iodine still going to this mass, so there are still parts of this tumor that are viable,” he said. “But I'm able to show that there is treatment response, which is something I wouldn't be able to do on a conventional CT.” Spectral CT also enables radiologists to choose different spectral/photon energy points for viewing images. At a low monochromatic keV of 45, the conspicuity of iodine within images can be increased, helping them to easily identify liver lesions and view differential enhancement of the pancreas. Conversely, a higher spectral/photon energy point allows for reductions in noise and artifacts. In addition, spectral CT’s Z-effective – the atomic energy display – color codes lesions for ready visualization.

 

 

Value vs. costs of Spectral CT

As hospital administrators evaluate the costs and benefits of conventional CT versus Spectral CT, several features should be considered to ensure Spectral CT will benefit the patient, hospital and referring community.  It’s critical to consider patient safety, diagnostic accuracy and efficiency of the CT suite. Ensuring an efficient workflow for technologists and radiologists is paramount as the industry faces a growing technologist shortage. It’s also worth noting that, in many cases, conventional CT can require more time to protocol patients compared to Spectral CT. Improving consistency from scan to scan is important, as well as driving throughput while maintaining patient safety and diagnostic accuracy.

Patient selection is also worth considering. Other dual-energy CTs in the market can’t image patients weighing more than 270 pounds or with a BMI of 30 or higher, due to the amount of energy that must be delivered with the lower energy source. Historically, a higher radiation burden was required to make low-dose sequences possible on larger patients. With Spectral CT 7500, the challenges of patient selection are negated and workflow issues can be significantly minimized, as Spectral CT has no weight limitations.  Dr. Toshav agreed these challenges can be largely mitigated with Philips’ new Spectral CT 7500, which provides spectral information for every patient without compromising image quality, dose, or workflow. The fast, always-on spectral detector delivers rich results in a single scan and requires no special protocols.

“The synthetic monoenergetic images created from the low- and high-energy detector-based imaging are actually better than the conventional imaging. There’s less noise, partly because of how Philips does dual energy from the detector. There is anti-correlating noise suppression, and because there is perfect co-registration with the detector-based imaging, Philips can lower the noise in these images,” said Dr. Toshav.

In addition, the single-source, dual-detector has expanded accessibility of spectral CT to obese patient populations previously considered inappropriate for dual-energy scanners. The dual-energy monoenergetic images provide excellent contrast and signal-to-noise ratio in these patients, and the scanners’ iodine maps are of diagnostic quality.  “We saw all of this without a dose penalty on the Spectral CT 7500. This is one of the ‘costs’ that was automatically reduced because dual-energy imaging was appropriate for the entire patient population because the dual-energy imaging is always there,” he said.

 

 

Cost savings and improved diagnostic certainty

Spectral detector CT helps salvage sub-optimal injection scans without requiring patients to be re-scanned, which shortens time to diagnosis. The Spectral CT 7500 was designed for first-time-right diagnosis; in a recent analysis, the technology reduced time to diagnosis by 34%, repeat scans by 25%, and follow-up scans by 30%.1

To fully understand the impact of these issues, Dr. Toshav led a cost-benefit analysis through a single-center, retrospective review of patients receiving contrasted abdominal and pelvic CT imaging.  They started with follow-up recommendations in three categories of exams: single-energy CT, dual-energy CT without the iodine map, and dual-energy CT with the iodine map. Findings showed that follow-up imaging was significantly lower after studies that used an iodine map. Combined, follow-up MRI and PET/CT exams dropped from 13% to 9.6%.

“We found that incomplete diagnosis was significantly higher in the conventional CT reports than in the iodine-mapped CT, dual-energy images,” he said.  Based on these findings, Dr. Toshav believes facilities using the Medicare reimbursement schedule for physician fees could realize significant cost savings with iodine-mapped, dual-energy CT versus conventional CT.  “We felt there was a strong potential for cost savings and multiple results suggesting improved radiologists’ diagnostic certainty with the dual-energy data sets,” concluded Dr. Toshav.

 

 

1Analysis by CARTI Cancer Center in Little Rock Arkansas and University Hospitals of Cleveland. Results from case studies are not predictive of results in other cases, which may vary.

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