Browsing by Author "Lofino, Ludovica"

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    Comparison of image quality of abdominal CT examinations and virtual noncontrast images between photon-counting and energy-integrating detector CT
    (2023-11-26) Lofino, Ludovica; Schwartz, fides; Ria, francesco; Zarei, Mojtaba; Samei, Ehsan; Abadia, Andres; Marin, Daniele
    Purpose: To compare image quality of portal venous phase (PVP) abdominal CT examinations and virtual non-contrast (VNC) images between photon-counting CT (PCCT) and energy-integratingDetector CT (EID). Methods and Materials: In this HIPAA compliant, IRB-approved, retrospective study, multi-phase CT scans from one commercially available PCCT (NAEOTOM Alpha, Siemens Healthineers) and two EID dual-source dual-energy CT systems (SOMATOM Definition Flash and SOMATOM Force, Siemens Healthineers) were retrieved. A total of 45 BMI-matched patients (21 women, 24 men; mean age58.5 ± 15.3 years, range 19-81 years; mean BMI 29.0 ± 6.8 kg/m2, range 13-47 kg/m2) were included: 15 for PCCT and 15 for each EID system. In vivo image quality parameters (MTFf10, noisemagnitude, Fav, Fpeak, NPSf10) were measured and compared between PCCT and EID for standard PVP and VNC images. A subset analysis was also performed in the overweight patient population(BMI>25 kg/m2). CTDIvol values were recorded for the three scanners. Because scanner tube current modulation adapts to patient size, radiation dose was compared among scanners accounting forBMI using a figure of merit: FOM=1/(BMI*lnCTDIvol). A five-point scale (1=best and 5=worst) was used to assess reader perception of noise, visibility of small structures, and overall image quality. Results: Compared to the two EID systems, PCCT yielded significantly improved resolution and noise magnitude for both PVP (MTFf10 = 0.55 ± 0.08 for PCCT vs. 0.50 ± 0.04 and 0.49 ± 0.03 for Flashand Force, P = 0.02; noise = 9.76 ± 3.10 vs. 15.35 ± 4.14 and 10.70 ± 1.34, P = 0.02) and VNC images (MTFf10 = 0.56 ± 0.01 for PCCT vs. 0.51 ± 0.05 and 0.51 ± 0.03 for Flash and Force, P = 0.02; noise =9.59 ± 2.77 vs. 13.90 ± 3.57 and 10.83 ± 2.83, P = 0.02). A similar statistically significant trend was confirmed in the smaller subset of overweight patients. Our FOM analysis suggests that, for equal radiation exposure levels and comparable patient size, PCCT yields 20% noise reduction compared to the two EID systems, with 18% reduction in overweight patients. Reader’s perceived image noise was significantly lower for PCCT compared to EID for both PVP (1.85 ± 0.88 vs. 2.60 ± 0.88 and 2.70 ± 0.80) and VNC images (1.95 ± 0.83 vs. 3.0 ± 0.97 and 2.90 ±0.85). Of note, overall image quality improved significantly for PCCT compared to EID (1.35 ± 0.67 vs. 2.60 ± 0.82 and 2.45 ± 0.69 for PVP and 1.50 ± 0.67 vs 2.85 ± 0.81 and 2.55 ± 0.60 for VNC). Conclusions: Compared to conventional EID systems, PCCT yields significantly lower radiation dose along with improved image quality on PVP and VNC images of abdominal CT examinations. Clinical Relevance/Application: PCCT has a lower radiation dose compared to EID CT, with better image quality parameters and lower noise magnitude.
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    ItemOpen Access
    Comparison of photon-counting and energy-integrating detector CT systems for the characterization of cystic renal lesions on virtual noncontrast imaging
    (2023-11-26) Lofino, Ludovica; Schwartz, Fides; Al Tarhuni, Mohammed; Abadia, Andres; Ria, Francesco; Samei, Ehsan; Marin, Daniele
    Purpose: The purpose of this study is to compare the absolute CT attenuation errors of cystic renal lesions and abdominal organs on virtual noncontrast images (VNC) between photon-counting (PCCT) and energy-integrating (EID) detector CT systems. Methods and Materials: In this HIPAA compliant, IRB-approved retrospective study, multiphase CT scans from one commercially available PCCT (NAEOTOM Alpha, Siemens Healthineers) and two EID dual-source dual-energy CT systems (SOMATOM Definition Flash and SOMATOM Force, Siemens Healthineers) were retrieved. A total of 56 BMI-matched patients (26 women, 30 men; mean age 58.5 ± 15.3 years; range 19-81 years, mean BMI 29.0 ± 6.8 kg/m2, range 13-47 kg/m2) were included: 16 for PCCT and 20 each per EID systems. Attenuation measurements of abdominal organs (liver, pancreas, spleen, kidney, and aorta) were recorded on VNC and True Noncontrast (TNC) datasets. Furthermore, attenuation measurements of 16 cystic renal lesions (eight for PCCT and eight for EID) were compared on VNC and TNC datasets. Absolute CT attenuation errors |HUVNC-HUTNC| were calculated and compared between PCCT and EID systems for the entire population and a subset of 20 obese patients (BMI: >30 kg/m2), using paired t-tests. Absolute CT attenuation errors were also compared for all cystic renal lesions and for renal lesions <1 cm, separately. *Results: PCCT yielded significantly lower absolute CT attenuation errors than EID using VNC in comparison with TNC images for the liver (4.3 ± 5.4 vs 8.8 ± 10.4), spleen (2.6 ± 6.2 vs 8.0 ± 10.3) and pancreas (4.4 ± 1.8 vs 7.7 ± 9.7) for all patients (P<0.01) and for spleen and pancreas in the obese patient cohort (P<0.05). Furthermore, PCCT yielded significantly lower absolute CT attenuation errors compared to EID for all cystic renal lesions (2.0 ± 1.3 vs. 12.0 ± 8.9; P<0.01) and for renal lesions <1 cm (1.4 ± 0.9 vs. 19.1 ± 6.8; P<0.01). Conclusions: PCCT yields significantly lower absolute CT attenuation errors for abdominal organs and cystic renal lesions in VNC images, compared to two dual-source dual-energy EID systems. Our results were corroborated in a subset of obese patients and small (<1 cm) renal lesions. Clinical Relevance/Application: Reliable CT attenuation values of virtual non-contrast imaging are necessary to replace true non-contrast acquisitions. This can be achieved with photon-counting CT with important implications in radiation dose reduction.