Purpose: To correlate patient diameters and subjective image quality in low-voltage and standard-voltage CT of the upper abdomen in the same patient population, with the goal of identifying cutoff patient diameters for selecting patients for low-voltage scans. Methods and Materials: 32 patients underwent MDCT of the abdomen with arterial phase at 80 kV with angular dose modulation on 64-row MDCT (test group). This was compared to a previous 120-kV scan on the same scanner. Mean interval between scans was 139 days. Patient transverse and sagittal diameters were measured at celiac axis level, and the mean was calculated. Two radiologists by consensus graded image quality on a 5-point scale (5=excellent; 4=good; 3=moderate; 2=poor; 1=non-diagnostic; 3 was the chosen cutoff quality). Image quality was correlated to the transverse, sagittal and mean diameter by means of an ANOVA test. Results: Patient diameters were unchanged across exams (all p=ns). In 80-kV scans, image quality was significantly correlated to sagittal (p=0.034) and mean diameters (p=0.025), while a trend to significance was observed for transverse diameter (p=0.053). In 120-kV scans, image quality was not significantly correlated to patient diameters (all p=ns), and all patients received grade 4 or 5. In 80-kV scans, a subjective grade 3 corresponded to a transverse diameter of 329 mm and a sagittal diameter of 267 mm. Conclusion: Subjective image quality in low-voltage scans appears to be more influenced by patient size than at standard voltage scans. For our protocol, cutoff diameters for adequate image quality are transverse 329 mm and sagittal 267 mm

Low-voltage CT of the abdomen: to identify cutoff patient diameters for patient selection through the analysis of correlation between patient diameters and subjective image quality

ZAMBONI, Giulia;POZZI MUCELLI, Roberto
2013

Abstract

Purpose: To correlate patient diameters and subjective image quality in low-voltage and standard-voltage CT of the upper abdomen in the same patient population, with the goal of identifying cutoff patient diameters for selecting patients for low-voltage scans. Methods and Materials: 32 patients underwent MDCT of the abdomen with arterial phase at 80 kV with angular dose modulation on 64-row MDCT (test group). This was compared to a previous 120-kV scan on the same scanner. Mean interval between scans was 139 days. Patient transverse and sagittal diameters were measured at celiac axis level, and the mean was calculated. Two radiologists by consensus graded image quality on a 5-point scale (5=excellent; 4=good; 3=moderate; 2=poor; 1=non-diagnostic; 3 was the chosen cutoff quality). Image quality was correlated to the transverse, sagittal and mean diameter by means of an ANOVA test. Results: Patient diameters were unchanged across exams (all p=ns). In 80-kV scans, image quality was significantly correlated to sagittal (p=0.034) and mean diameters (p=0.025), while a trend to significance was observed for transverse diameter (p=0.053). In 120-kV scans, image quality was not significantly correlated to patient diameters (all p=ns), and all patients received grade 4 or 5. In 80-kV scans, a subjective grade 3 corresponded to a transverse diameter of 329 mm and a sagittal diameter of 267 mm. Conclusion: Subjective image quality in low-voltage scans appears to be more influenced by patient size than at standard voltage scans. For our protocol, cutoff diameters for adequate image quality are transverse 329 mm and sagittal 267 mm
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11562/532550
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