Image quality of photon counting and energy integrating chest CT-Prospective head-to-head comparison on same patients

Purpose: To prospectively compare the image quality of high-resolution, low-dose photon-counting detector CT (PCD-CT) with standard energy-integrating-detector CT (EID) on the same patients. Method: IRB-approved, prospective study; patients received same-day non-contrast CT on EID and PCD-CT (NAEOTOM Alpha, blinded) with clinical protocols. Four blinded radiologists evaluated subsegmental bron-chial wall definition, noise, and overall image quality in randomized order (0 = worst; 100 = best). Cases were quantitatively compared using the average Global-Noise-Index (GNI), Noise-Power-Spectrum average frequency (fav), NPS frequency-peak (fpeak), Task-Transfer-Function-10%-frequency (f10) an adjusted detectability index (d'adj), and applied output radiation doses (CTDIvol).Results: Sixty patients were prospectively imaged (27 men, mean age 67 & PLUSMN; 10 years, mean BMI 27.9 & PLUSMN; 6.5, 15.9-49.4 kg/m2). Subsegmental wall definition was rated significantly better for PCD-CT than EID (mean 71 [56-87] vs 60 [45-76]; P < 0.001), noise was rated higher for PCD-CT (48 [26-69] vs 34 [13-56]; P < 0.001). Overall image quality was rated significantly higher for PCD-CT than EID (66 [48-85] vs 61 [42-79], P = 0.008). Automated image quality measures showed similar differences for PCD-CT vs EID (mean GNI 70 & PLUSMN; 19 HU vs 26 & PLUSMN;8 HU, fav0.35 & PLUSMN; 0.02 vs 0.25 & PLUSMN; 0.02 mm � 1, fpeak0.07 & PLUSMN; 0.01 vs 0.09 & PLUSMN; 0.03 mm � 1, f10 0.7 & PLUSMN; 0.08 vs 0.6 & PLUSMN; 0.1 mm-1, all p-values < 0.001). PCD-CT showed a 10% average d'adj increase (-49% min, 233% max). PCD-CT studies were acquired at significantly lower radiation doses than EID (mean CTDIvol 4.5 & PLUSMN; 2.1 vs 7.7 & PLUSMN; 3.2 mGy, P < 0.01).Conclusion: Though PCD-CT had higher measured and perceived noise, it offered equivalent or better diagnostic quality compared to EID at lower radiation doses, due to its improved resolution.

Automated summary

This study compared the image quality between high-resolution, low-dose photon-counting detector CT (PCD-CT) and standard energy-integrating detector CT (EID) on the same patients. The results showed that PCD-CT had better subsegmental bronchial wall definition, higher noise, and overall image quality compared to EID. PCD-CT provided equivalent or better diagnostic quality at lower radiation doses, thanks to its improved resolution.