Qualitative and Quantitative Assessment of Noncontrast Head CT Quality on a Newer-Generation Portable Scanner

Objective: Portable computed tomography (CT) scanners allow bedside brain imaging in critically ill patients without the risks of transport, but historically these scanners have demonstrated image quality inferior to that of fixed scanners. In this study, the quality of head CT examinations using a newer-generation portable scanner, the On.site, was compared with that of an older-generation portable scanner, the CereTom, as well as to that of fixed CT scanners. Methods: Head CT examinations performed on the On.site scanner were retrospectively compared with those conducted on the same patient within 24 hours using the CereTom scanner or fixed scanners. A similar analysis was also carried out between the CereTom and fixed scanners. Three neuroradiologists rated the images qualitatively. Quantitative assessment included signal difference to noise ratio (SdNR) and noise magnitude in the cerebrospinal fluid, bone, and pons. Results: The On.site scanner had higher image quality scores than the CereTom scanner ( P <0.001) and was 10 to 20 times less likely to produce subpar images. Mean noise in the pons was slightly higher with On.site than with CereTom ( P =0.014). Fixed scanners had higher qualitative scores than the On.site scanner, but there was no significant difference between the scanners in the probability of producing subpar images. The CereTom scanner had significantly lower qualitative scores than fixed scanners, and significantly increased probability of producing subpar and nondiagnostic images ( P <0.001). The SdNR was lower with the On.site scanner than with the fixed scanners ( P <0.001). Noise magnitude measures were higher with On.site than with fixed scanners ( P <0.001 for all). Conclusions: The On.site scanner had significantly better qualitative image quality than the CereTom scanner and had a much lower probability of producing subpar or nondiagnostic images. Although the On.site scanner had inferior qualitative and quantitative image quality compared with the fixed scanners, there was no significant difference in the probability of producing subpar or nondiagnostic images. This may indicate a decreased need to transport sick patients out of the neurological intensive care unit for imaging in the future.