Balancing Radiation and Contrast Media Dose in Single-Pass Abdominal Multidetector CT: Prospective Evaluation of Image Quality

Acad Radiol. 2015 Nov;22(11):1419-26. doi: 10.1016/j.acra.2015.06.016. Epub 2015 Aug 8.

Abstract

Rationale and objectives: As both contrast and radiation dose affect the quality of CT images, a constant image quality in abdominal contrast-enhanced multidetector computed tomography (CE-MDCT) could be obtained balancing radiation and contrast media dose according to the age of the patients.

Materials and methods: Seventy-two (38 Men; 34 women; aged 20-83 years) patients underwent a single-pass abdominal CE-MDCT. Patients were divided into three different age groups: A (20-44 years); B (45-65 years); and C (>65 years). For each group, a different noise index (NI) and contrast media dose (370 mgI/mL) was selected as follows: A (NI, 15; 2.5 mL/kg), B (NI, 12.5; 2 mL/kg), and C (NI, 10; 1.5 mL/kg). Radiation exposure was reported as dose-length product (DLP) in mGy × cm. For quantitative analysis, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were calculated for both the liver (L) and the abdominal aorta (A). Statistical analysis was performed with a one-way analysis of variance. Standard imaging criteria were used for qualitative analysis.

Results: Although peak hepatic enhancement was 152 ± 16, 128 ± 12, and 101 ± 14 Hounsfield units (P < .001) for groups A, B, and C, respectively, no significant differences were observed in the corresponding SNRL with 9.2 ± 1.4, 9.1 ± 1.2, and 9.2 ± 3. Radiation (mGy × cm) and contrast media dose (mL) administered were 476 ± 147 and 155 ± 27 for group A, 926 ± 291 and 130 ± 16 for group B, and 1981 ± 451 and 106 ± 15 for group C, respectively (P < .001). None of the studies was graded as poor or inadequate by both readers, and the prevalence-adjusted bias-adjusted kappa ranged between 0.48 and 0.93 for all but one criteria.

Conclusions: A constant image quality in CE-MDCT can be obtained balancing radiation and contrast media dose administered to patients of different age.

Keywords: CT protocols; CT technique; contrast media; effective dose; image quality.

MeSH terms

  • Abdomen / diagnostic imaging*
  • Adult
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Contrast Media / administration & dosage*
  • Female
  • Humans
  • Image Enhancement*
  • Male
  • Middle Aged
  • Multidetector Computed Tomography / methods*
  • Prospective Studies
  • Radiation Dosage*

Substances

  • Contrast Media