News & Events

News & Events

A poster titled, “The Association between 16-slice versus 64-slice Computed Tomography Angiography of the Neck and Subsequent Invasive Cerebrovascular Angiography” has been presented at the 2020 American College of Radiology Annual Meeting, which was held virtually from May 16th to 19th. The study was produced by the ongoing outcomes research collaboration between HealthHelp and Humana. HealthHelp’s DiagnosticSite site certification program captures information on the diagnostic imaging equipment present at outpatient facilities. Information on the models of computed tomography (CT) machines used by different facilities, held within the site certification program’s database, was combined with Humana claims data to gain insights into how the type of CT machine used influences care outcomes.

While there is evidence that CT studies performed on machines with more slices have higher positive and negative predictive value, the association between the type of CT machine used to perform initial imaging and downstream patient care has not been well studied. To explore this issue, this study examines whether claims for CT angiography of the neck performed on a 64-slice CT machine are less likely to be followed by invasive cerebrovascular angiography (ICA) in the subsequent 60 days than those performed on a 16-slice CT machine. As catheterization has a 1.7% major complication rate, reducing the ICA rate has a potential impact on patient safety.

Health insurance claims pertaining to adults with commercial or Medicare Advantage health plans were extracted from a database. Claims were included if they pertained to patients receiving CT angiography of the neck between September 15, 2017 and September 14, 2018, the patients were continuously enrolled in their health plan from 90 days prior to 60 days post, and they did not receive CT, magnetic resonance imaging, or positron emission tomography of the head or neck, or a catheterization or a percutaneous coronary intervention, in the 90 days prior to CT. Site certification data were used to label CT claims as 16-slice, 64-slice, or neither/unknown. Patients’ claims in the 60 days post-CT were examined for performance of ICA. The association between slices and ICA claims was tested using a Chi-square test. An adjusted analysis was additionally conducted using logistic regression.

A total of 1,766 claims met selection criteria. Of these, 63.7% (1,125) related to CT performed on a 64-slice machine. Claims for 16-slice CT had a 5.1% (33/641) subsequent ICA rate, while claims for 64-slice CT had a 3.1% (35/1,125) subsequent ICA rate (P<.05). The adjusted analysis found that there was a significant association between the number of slices and subsequent ICA (OR: 1.64; 95% CI: 1.00-2.69). The study concluded that encouraging clinicians to direct patients towards 64-slice CT may reduce downstream invasive testing and unnecessary radiation exposure, while improving patient experience.

In response to the study’s findings, the study’s lead author, Adam C. Powell, Ph.D., remarked, “By combining HealthHelp’s site certification data with Humana’s claims data, we were able to improve our understanding of how the diagnostic imaging equipment used to provide care may impact the outcomes that patients experienced. As claims data do not indicate the type of CT machine used to produce an image, we were in a unique position to study this question using a national sample. Our team found that 64-slice CT was associated with less downstream invasive testing than 16-slice CT. This suggests that by encouraging the use of 64-slice CT, it may be possible to enhance the quality of care that patients receive.”

To learn more about the 2020 American College of Radiology Annual Meeting, visit