RESUMO
PURPOSE: To compare image quality, iodine intake, and radiation dose in overweight and obese patients undergoing abdominal computed tomography (CT) enhancement using different scanning modes and contrast medium. METHODS: Ninety overweight and obese patients (25âkg/m2≤body mass index (BMI)<â30âkg/m2 and BMI≥30âkg/m2) who underwent abdominal CT-enhanced examinations were randomized into three groups (A, B, and C) of 30 each and scanned using gemstone spectral imaging (GSI) +320âmgI/ml, 100âkVp + 370âmgI/ml, and 120âkVp + 370âmgI/ml, respectively. Reconstruct monochromatic energy images of group A at 50-70âkeV (5âkeV interval). The iodine intake and radiation dose of each group were recorded and calculated. The CT values, contrast-to-noise ratios (CNRs), and subjective scores of each subgroup image in group A versus images in groups B and C were by using one-way analysis of variance or Kruskal-Wallis H test, and the optimal keV of group A was selected. RESULTS: The dual-phase CT values and CNRs of each part in group A were higher than or similar to those in groups B and C at 50-60âkeV, and similar to or lower than those in groups B and C at 65âkeV and 70âkeV. The subjective scores of the dual-phase images in group A were lower than those of groups B and C at 50âkeV and 55âkeV, whereas no significant difference was seen at 60-70âkeV. Compared to groups B and C, the iodine intake in group A decreased by 12.5% and 13.3%, respectively. The effective doses in groups A and B were 24.7% and 25.8% lower than those in group C, respectively. CONCLUSION: GSI +320âmgI/ml for abdominal CT-enhanced in overweight patients satisfies image quality while reducing iodine intake and radiation dose, and the optimal keV was 60âkeV.
Assuntos
Meios de Contraste , Obesidade , Sobrepeso , Radiografia Abdominal , Tomografia Computadorizada por Raios X , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade/diagnóstico por imagem , Sobrepeso/diagnóstico por imagem , Doses de Radiação , Intensificação de Imagem Radiográfica/métodos , Radiografia Abdominal/métodos , Tomografia Computadorizada por Raios X/métodos , Idoso de 80 Anos ou maisRESUMO
OBJECTIVES: To investigate the feasibility of low-concentration contrast media (LC-CM) in cerebral and cervical dual-energy CT angiography (DE-CTA) using an advanced monoenergetic (Mono+) reconstruction technique. METHODS: Sixty-five consecutive patients prospectively selected to undergo cerebral and cervical DE-CTA were randomised into two groups: 32 patients (63.7 ± 9.7 years) in the high-concentration contrast medium (HC-CM) group with iopromide 370 and 33 patients (60.7 ± 10.8 years) in the low-concentration contrast medium (LC-CM) group with iodixanol 270. Traditional monoenergetic (Mono) and Mono+ images from 40 to 100 keV levels (at 10-keV intervals) and the standard mixed (Mixed, 120 kVp equivalent) images were reconstructed. Subjective image quality parameters included the contrast-to-noise ratio (CNR) and objective image quality parameters were evaluated and compared between the two groups. RESULTS: The 40-keV Mono+ images in the LC-CM group showed comparable objective CNR (common carotid arteries: 83.7 ± 24.5 vs. 78.1 ± 23.2; internal carotid arteries: 82.2 ± 26.8 vs. 76.8 ± 24.1; middle cerebral arteries: 72.5 ± 24.6 vs. 70.6 ± 19.2; all p > 0.05) and subjective image scores (3.95 ± 0.19 vs. 3.83 ± 0.35; p > 0.05) compared with Mixed images in the HC-CM group. CONCLUSION: The Mono+ reconstruction technique could reduce the concentration of iodinated CM in the diagnosis of cerebral and cervical angiography. KEY POINTS: ⢠Mono+ shows decreased noise and superior CNR compared with Mono. ⢠The 40-keV Mono+ images show the highest CNR in the LC-CM group. ⢠The Mono+ reconstruction technique could reduce the concentration of iodinated CM.
Assuntos
Encéfalo/diagnóstico por imagem , Angiografia por Tomografia Computadorizada/métodos , Meios de Contraste/administração & dosagem , Iohexol/análogos & derivados , Pescoço/diagnóstico por imagem , Intensificação de Imagem Radiográfica , Imagem Radiográfica a Partir de Emissão de Duplo Fóton/métodos , Ácidos Tri-Iodobenzoicos/administração & dosagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Artéria Carótida Primitiva/diagnóstico por imagem , Artéria Carótida Interna/diagnóstico por imagem , Estudos de Viabilidade , Feminino , Humanos , Iohexol/administração & dosagem , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Razão Sinal-RuídoRESUMO
AIM: To evaluate the feasibility of low contrast medium and radiation dose for hepatic computed tomography (CT) perfusion of rabbit VX2 tumor. METHODS: Eleven rabbits with hepatic VX2 tumor underwent perfusion CT scanning with a 24-h interval between a conventional tube potential (120 kVp) protocol with 350 mgI/mL contrast medium and filtered back projection, and a low tube potential (80 kVp) protocol with 270 mgI/mL contrast medium with iterative reconstruction. Correlation and agreement among perfusion parameters acquired by the conventional and low dose protocols were assessed for the viable tumor component as well as whole tumor. Image noise and tumor-to-liver contrast to noise ratio during arterial and portal venous phases were evaluated. RESULTS: A 38% reduction in contrast medium dose (360.1 ± 13.3 mgI/kg vs 583.5 ± 21.5 mgI/kg, P < 0.001) and a 73% decrease in radiation dose (1898.5 mGy ⢠cm vs 6951.8 mGy ⢠cm) were observed. Interestingly, there was a strong positive correlation in hepatic arterial perfusion (r = 0.907, P < 0.001; r = 0.879, P < 0.001), hepatic portal perfusion (r = 0.819, P = 0.002; r = 0.831, P = 0.002), and hepatic blood flow (r = 0.945, P < 0.001; r = 0.930, P < 0.001) as well as a moderate correlation in hepatic perfusion index (r = 0.736, P = 0.01; r = 0.636, P = 0.035) between the low dose protocol with iterative reconstruction and the conventional protocol for the viable tumor component and the whole tumor. These two imaging protocols provided a moderate but acceptable agreement for perfusion parameters and similar tumor-to-liver CNR during arterial and portal venous phases (5.63 ± 2.38 vs 6.16 ± 2.60, P = 0.814; 4.60 ± 1.27 vs 5.11 ± 1.74, P = 0.587). CONCLUSION: Compared with the conventional protocol, low contrast medium and radiation dose with iterative reconstruction has no significant influence on hepatic perfusion parameters for rabbits VX2 tumor.