Elsevier

Academic Radiology

Volume 16, Issue 8, August 2009, Pages 934-939
Academic Radiology

Original investigation
Volumetric Measurement Pulmonary Ground-Glass Opacity Nodules with Multi-detector CT: Effect of Various Tube Current on Measurement Accuracy—A Chest CT Phantom Study

https://doi.org/10.1016/j.acra.2009.02.020Get rights and content

Rationale and Objectives

The purpose of this study was to evaluate the effect of various tube currents on the accuracy of volumetric measurements of ground-glass opacity (GGO) nodules using a chest phantom.

Materials and Methods

A chest phantom containing 13 artificial GGO nodules with known volumes was scanned using a 64-slice computed tomographic scanner at different tube currents (30, 60, 90, 120, 150, 180, and 210 mA). Volumetric measurements were performed using software. The relative percentage error and the absolute percentage error between the volume measures on computed tomography and the reference-standard volumes were calculated. Correlations between the mean absolute percentage error and the mean attenuation of nodules and between the ratio of solid component and the mean attenuation of nodules were analyzed.

Results

The relative percentage errors showed that there was substantial underestimation of nodule volumes at 30, 60, and 90 mA and substantial overestimation of volumes at 120, 150, 180, and 210 mA, but there was no statistically significant difference in absolute percentage errors (P = .876). Pearson's correlation coefficient of the mean absolute percentage errors of nodules on volumetric measurement versus the mean attenuation value of nodules showed a negative correlation, and the ratio of solid component to whole nodule versus the mean attenuation of nodules showed a positive correlation.

Conclusion

Volume measurement is a promising method for the quantification of GGO nodule volume. It is important to know that different tube currents can affect the accuracy of volumetric measurements.

Section snippets

Phantom

A chest phantom was used to replicate a 110-mm-thick transverse section of a human thorax. This phantom uses an acrylic container constructed to simulate a outline of chest. The thoracic cavity was filled with ground cork to simulate the lung parenchyma (13) (Fig 1); the mean CT attenuation of the cork was −910.56 ± 45.06 Hounsfield units (HU). The mediastinum and chest wall were simulated by gelatin (chemically pure; Sinopharm Chemical Reagent Co Ltd, Shanghai, China); the mean CT attenuation

Results

Segmentation and calculation were successful for all nodules (Fig 3). The reference-standard volumes in the nodules ranged from 589 to 897 mm3. The mean CT attenuation of nodules ranged from −633.22 ± 51.12 to −147.36 ± 28.62 HU.

The APEs of GGO nodules on volumetric measurement ranged from 0.14% to 22.67%. Table 1 shows the mean APE and the mean RPE of GGO nodules on volumetric measurement obtained with different tube currents; there was no statistically significant difference in the mean APEs.

Discussion

Recent advances in imaging technology enable the precise three-dimensional volumetric measurement of pulmonary nodules. In patients with solid nodules, volumetric measurements are said to be more accurate than the use of traditional one-dimensional or two-dimensional measurement methods 11, 12, 14, 17. For volumetric analysis of GGO nodules to be useful, the volume measurement software must be both accurate and reproducible.

The volumetric software used in this study showed good overall

References (24)

  • T. Aoki et al.

    Peripheral lung adenocarcinoma: correlation of thin-section CT findings with histologic prognostic factors and survival

    Radiology

    (2001)
  • S.G. Jennings et al.

    Lung tumor growth: assessment with CT—comparison of diameter and cross-sectional area with volume measurements

    Radiology

    (2004)
  • Cited by (32)

    • Volumetric measurement of artificial pure ground-glass nodules at low-dose CT: Comparisons between hybrid iterative reconstruction and filtered back projection

      2015, European Journal of Radiology
      Citation Excerpt :

      Regarding the volumetric measurement of solid nodules, previous studies have reported that the volume measurement was not affected by exposure dose reduction even at an ultra-low-dose level (120 kV, 5 mAs, FBP) or reduced tube voltage and tube current-time product (80 kV, 25 mAs, both FBP and IR) [7,16]. In addition, studies on volumetry focusing on pure GGNs without IR showed that there were no significant differences in diagnostic accuracy among various dose levels [17,18]. Moreover, recent investigations have reported that iterative reconstruction did not have an adverse impact on the volume measurement of pulmonary nodules [7–11].

    • Influence of radiation dose and iterative reconstruction algorithms for measurement accuracy and reproducibility of pulmonary nodule volumetry: A phantom study

      2014, European Journal of Radiology
      Citation Excerpt :

      A prerequisite is the preservation of diagnostic accuracy and feasibility of nodule measurements. Previous research dealt with the volumetric analysis of pulmonary nodules with respect to a reduced radiation dose [8–12], IR algorithms [13] or both [14–17] as well as reported the availability of semi-automated volumetry in the setting of low radiation dose and IR applications. However, IMR has not been investigated to date and research is limited on the effect of CT radiation dose and reconstruction algorithms for the accuracy and reproducibility of volumetric measurement.

    • Impact of the adaptive statistical iterative reconstruction technique on image quality in ultra-low-dose CT

      2013, Clinical Radiology
      Citation Excerpt :

      The study was approved by the ethics committee of Beijing Friendship Hospital, Capital Medical University. A chest CT phantom was used to simulate an 11 cm thick transverse section of the thorax.16 The phantom was 30 cm in width (left to right), 20 cm in height (anterior to posterior), and 11 cm in length (superior to inferior) when placed such that its positioning emulates a patient in the supine orientation.

    View all citing articles on Scopus
    View full text