Visual assessment of calcification in solitary pulmonary nodules on chest radiography: correlation with volumetric quantification of calcification

  • Seulgi You
  • Eun Young Kim
  • Kyung Joo Park
  • Joo Sung Sun



To assess the ability of digital chest radiography (CXR) to reveal calcification in solitary pulmonary nodules (SPNs), and to examine the correlation between a visual assessment and volumetric quantification of the calcification.

Materials and methods

This study was a retrospective review of 220 SPNs identified by both CXR and chest CT. Eleven observers did blind review of the CXR images and scored nodule calcification on a confidence scale of 1 to 5. The area under the receiver operating characteristics (ROC) curve (AUC) was obtained to analyze the diagnostic performance. The intraclass correlation coefficient (ICC) for interrater reliability was calculated. The AUC and ICC were calculated according to the following nodule diameter groups: group 1 (< 10 mm), group 2 (≥ 10 mm and < 20 mm), and group 3 (≥ 20 mm).


Of the 220 SPNs, 145 SPNs (65.6%) were identified as non-calcified and 75 (34.4%) as calcified. The average percentage of calcification volume in SPN > 160 HU (Vol160HU) among the 75 calcified nodules was 47.5%. The mean Vol160HU of the 68 SPNs classified as having definite calcification was 51.1%. The overall AUC was 0.71. The AUCs for groups 1, 2, and 3 was 0.835, 0.639, and 0.620, respectively. The ICCs for groups 1, 2, 3 was 0.65, 0.48, and 0.33, respectively.


The overall diagnostic performance of digital CXR to predict calcification in SPNs was moderately accurate and the diagnostic performance for predicting calcification in SPNs was significantly higher, and interobserver reproducibility was good when SPN < 10 mm compared with ≥ 10 mm in diameter.

Key Points

• The misdiagnosis of a non-calcified nodule as a calcified one by CXR could lead to poor management choices for the SPN.

• The diagnostic performance of CXR in predicting calcification was best for nodules < 10 mm in diameter. SPNs with calcification of approximately 50% of their volume tend to be considered calcified.

• The diagnostic performance of CXR in identifying calcification was low for nodules ≥ 10 mm in diameter; therefore, we should carefully evaluate calcification carefully for nodules ≥ 10 mm.


Solitary pulmonary nodule Radiography, thoracic Tomography, X-ray computed 



Automatic exposure control


Area under the ROC curve


Confidence interval


Computed tomography


Chest radiography


False positive


Intraclass correlation coefficient


Multidetector CT


Negative predictive value


Positive predictive value


Receiver operating characteristic


Solitary pulmonary nodules



This research was supported by the MSIT (Ministry of Science and ICT), Korea, under the ITRC (Information Technology Research Center) support program (IITP-2018-2016-0-00309) supervised by the IITP (Institute for Information and Communications Technology Promotion).

Compliance with ethical standards


The scientific guarantor of this publication is Joo Sung Sun.

Conflict of interest

The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.

Statistics and biometry

No complex statistical methods were necessary for this paper.

Informed consent

Written informed consent was waived by the Institutional Review Board.

Ethical approval

Institutional Review Board approval was obtained.


• Retrospective

• Observational

• Performed at one institution


  1. 1.
    Tan BB, Flaherty KR, Kazerooni EA, Iannettoni MD, American College of Chest Physicians (2003) The solitary pulmonary nodule. Chest 123:89S–96SGoogle Scholar
  2. 2.
    Shah PK, Austin JH, White CS et al (2003) Missed non-small cell lung cancer: radiographic findings of potentially resectable lesions evident only in retrospect. Radiology 226:235–241CrossRefGoogle Scholar
  3. 3.
    Steele JD (1963) The solitary pulmonary nodule. Report of a cooperative study of resected asymptomatic solitary pulmonary nodules in males. J Thorac Cardiovasc Surg 46:21–39PubMedGoogle Scholar
  4. 4.
    Siegelman SS, Khouri NF, Leo FP, Fishman EK, Braverman RM, Zerhouni EA (1986) Solitary pulmonary nodules: CT assessment. Radiology 160:307–312CrossRefGoogle Scholar
  5. 5.
    Zerhouni EA, Stitik FP, Siegelman SS et al (1986) CT of the pulmonary nodule: a cooperative study. Radiology 160:319–327CrossRefGoogle Scholar
  6. 6.
    Gurney JW, Lyddon DM, McKay JA (1993) Determining the likelihood of malignancy in solitary pulmonary nodules with Bayesian analysis. Part II. Application. Radiology 186:415–422CrossRefGoogle Scholar
  7. 7.
    Bateson EM (1965) An analysis of 155 solitary lung lesions illustrating the differential diagnosis of mixed tumours of the lung. Clin Radiol 16:51–65CrossRefGoogle Scholar
  8. 8.
    Yankelevitz DF, Henschke CI (2000) Small solitary pulmonary nodules. Radiol Clin North Am 38:471–478CrossRefGoogle Scholar
  9. 9.
    Henschke CI, McCauley DI, Yankelevitz DF et al (1999) Early lung cancer action project: overall design and findings from baseline screening. Lancet 354:99–105CrossRefGoogle Scholar
  10. 10.
    Proto AV, Thomas SR (1985) Pulmonary nodules studied by computed tomography. Radiology 156:149–153CrossRefGoogle Scholar
  11. 11.
    Tang AW, Moss HA, Robertson RJ (2003) The solitary pulmonary nodule. Eur J Radiol 45:69–77CrossRefGoogle Scholar
  12. 12.
    Adebonojo SA (1975) Evaluation and management of solitary pulmonary nodules. Am Surg 41:806–813PubMedGoogle Scholar
  13. 13.
    Leef JL 3rd, Klein JS (2002) The solitary pulmonary nodule. Radiol Clin North Am 40:123–143 ixCrossRefGoogle Scholar
  14. 14.
    Caskey CI, Templeton PA, Zerhouni EA (1990) Current evaluation of the solitary pulmonary nodule. Radiol Clin North Am 28:511–520PubMedGoogle Scholar
  15. 15.
    Grewal RG, Austin JH (1994) CT demonstration of calcification in carcinoma of the lung. J Comput Assist Tomogr 18:867–871CrossRefGoogle Scholar
  16. 16.
    Khan AN, Al-Jahdali HH, Allen CM, Irion KL, Al Ghanem S, Koteyar SS (2010) The calcified lung nodule: what does it mean? Ann Thorac Med 5:67–79CrossRefGoogle Scholar
  17. 17.
    Berger WG, Erly WK, Krupinski EA, Standen JR, Stern RG (2001) The solitary pulmonary nodule on chest radiography: can we really tell if the nodule is calcified? AJR Am J Roentgenol 176:201–204CrossRefGoogle Scholar
  18. 18.
    Ketai L, Malby M, Jordan K, Meholic A, Locken J (2000) Small nodules detected on chest radiography: does size predict calcification? Chest 118:610–614CrossRefGoogle Scholar
  19. 19.
    Woodard PK, Slone RM, Sagel SS et al (1998) Detection of CT-proved pulmonary nodules: comparison of selenium-based digital and conventional screen-film chest radiographs. Radiology 209:705–709CrossRefGoogle Scholar
  20. 20.
    Siegelman SS, Zerhouni EA, Leo FP, Khouri NF, Stitik FP (1980) CT of the solitary pulmonary nodule. AJR Am J Roentgenol 135:1–13CrossRefGoogle Scholar
  21. 21.
    Khouri NF, Meziane MA, Zerhouni EA, Fishman EK, Siegelman SS (1987) The solitary pulmonary nodule. Assessment, diagnosis, and management. Chest 91:128–133CrossRefGoogle Scholar
  22. 22.
    Greiner M, Pfeiffer D, Smith RD (2000) Principles and practical application of the receiver-operating characteristic analysis for diagnostic tests. Prev Vet Med 45:23–41CrossRefGoogle Scholar
  23. 23.
    Landis JR, Koch GG (1977) The measurement of observer agreement for categorical data. Biometrics 33:159–174CrossRefGoogle Scholar
  24. 24.
    Theros EG (1977) 1976 Caldwell lecture: varying manifestation of peripheral pulmonary neoplasms: a radiologic-pathologic correlative study. AJR Am J Roentgenol 128:893–914CrossRefGoogle Scholar
  25. 25.
    Jain DG (2012) Cancer in the solitary pulmonary nodule. Journal, Indian Academy of Clinical Medicine JIACM 13(2):116–126Google Scholar
  26. 26.
    Quekel LG, Kessels AG, Goei R, van Engelshoven JM (1999) Miss rate of lung cancer on the chest radiograph in clinical practice. Chest 115:720–724CrossRefGoogle Scholar
  27. 27.
    O'Keefe ME Jr, Good CA, McDonald JR (1957) Calcification in solitary nodules of the lung. Am J Roentgenol Radium Ther Nucl Med 77:1023–1033PubMedGoogle Scholar
  28. 28.
    Mahoney MC, Shipley RT, Corcoran HL, Dickson BA (1990) CT demonstration of calcification in carcinoma of the lung. AJR Am J Roentgenol 154:255–258CrossRefGoogle Scholar

Copyright information

© European Society of Radiology 2019

Authors and Affiliations

  1. 1.Department of RadiologyAjou University Medical CenterSuwonSouth Korea
  2. 2.Department of RadiologyHankook HospitalCheongjuSouth Korea

Personalised recommendations