“PCCT was associated with superior quantitative and subjective image quality in both vascular and parenchymal structures in intraindividual comparisons with energy-integrating detector CT,” pointed out lead study author Jan Hegmanns, who is affiliated with the Institute of Diagnostic and Interventional Radiology and Neuroradiology at University Hospital Essen in Essen, Germany, and colleagues.
The study authors noted that increased SNR differences between PCCT and EID-CT in parenchymal organs and vessels paralleled increases in body mass index (BMI).
Three Key Takeaways
• Better image quality in patients with obesity. In this intraindividual comparison of 51 patients, photon-counting CT (PCCT) gave significantly higher signal-to-noise ratio (SNR) than energy-integrating detector CT (EID-CT) in both vascular structures and parenchymal organs. SNR in the ascending aorta was 19.65 vs. 13.22, and in the liver 5.53 vs. 4.71. Readers also rated contrast, sharpness and overall image quality higher with PCCT. The SNR advantage grew as BMI increased, so the benefit may be largest in the patients whose scans usually suffer most from attenuation and scatter.
• Meaningful dose reduction. PCCT reduced median CTDIvol by nearly 30 percent (11.99 vs. 17.05 mGy) and median DLP by about 26 percent (526.25 vs. 709.32 mGy·cm). This may support safer longitudinal imaging in patients with obesity who need frequent follow-up. The authors suggest further dose reduction may be possible without losing diagnostic quality.
• Interpret with caution pending further validation. This was a single-center retrospective study. Acquisition parameters differed between the two scanner types, and only two radiologists rated subjective image quality. Quantitative measurements came from a single contrast-enhanced section per site. Prospective, multicenter studies with matched protocols would strengthen the case for preferring PCCT in this population.
Photon-counting CT also facilitated a nearly 30 percent reduction of volume CT dose index (CTDIvol) with a median CTDIvol of 11.99 mGy in comparison to 17.05 mGy, according to the study authors. The researchers pointed out a nearly 26 percent reduction in median dose-length product (DLP) with PCCT (526.25 mGy cm vs. 709.32 mGy cm).
“These advantages are particularly relevant in patients with obesity, where increased attenuation and scatter typically degrade image quality. The combination of meaningful dose reduction and improved SNR may support safer longitudinal imaging strategies in patient groups requiring frequent follow-up. Our findings further indicate that additional dose reduction may be feasible without compromising diagnostic integrity,” emphasized Hegmanns and colleagues.
(Editor’s note: For related content, see “Does kV Still Matter in Photon-Counting CT?,””CT Radiation Dosing: Where Things Stand, Part 1” and “Could Photon-Counting CT Supplant Echocardiography for Primary Imaging of Transcatheter Heart Valves?”)
Beyond the inherent limitations of a single-center retrospective study, the researchers acknowledged differences in image acquisition parameters with EID-CT and PCCT, subjective image quality evaluations from two radiologists and quantitative analysis derived from one contrast-enhanced section per measurement site.
