Solitary pulmonary nodule: characterization with combined wash-in and washout features at dynamic multi-detector row CT

Radiology. 2005 Nov;237(2):675-83. doi: 10.1148/radiol.2372041549.


Purpose: To prospectively assess the accuracy of combined wash-in and washout characteristics at dynamic contrast material-enhanced multi-detector row computed tomography (CT) in distinguishing benign from malignant solitary pulmonary nodules.

Materials and methods: Institutional review board approval and informed consent were obtained. The study included 107 patients (62 men, 45 women; mean age, 55 years; range, 22-81 years) with a solitary pulmonary nodule. After unenhanced CT (2.5-mm collimation) scans were obtained, dynamic CT was performed by using a helical technique (series of images obtained throughout the nodule, with 2.5-mm collimation, at 30, 60, 90, and 120 seconds and 4, 5, 9, 12, and 15 minutes) after intravenous injection of contrast medium (120 mL). Tissue diagnosis was made in 70 nodules, and follow-up images showed benignancy in the remaining 37 (no change in size, n = 32; decrease in size, n = 5). CT findings were analyzed in terms of wash-in and washout of contrast medium. Sensitivity, specificity, and accuracy for malignant nodules were calculated by considering both the wash-in and washout characteristics at dynamic CT.

Results: There were 49 malignant and 58 benign nodules. When diagnostic criteria for malignancy of both wash-in of 25 HU or greater and washout of 5-31 HU were applied, sensitivity, specificity, and accuracy for malignancy were 94% (46 of 49 nodules), 90% (52 of 58 nodules), and 92% (98 of 107 nodules), respectively. Of 58 benign nodules, 27 showed less than 25 HU wash-in, 14 showed persistent contrast enhancement without washout and with wash-in of 25 HU or greater, and 11 showed washout greater than 31 HU and wash-in of 25 HU or greater.

Conclusion: Evaluation of solitary pulmonary nodules by analyzing combined wash-in and washout characteristics at dynamic contrast-enhanced multi-detector row CT showed 92% accuracy for distinguishing benign nodules from malignant nodules.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Chi-Square Distribution
  • Contrast Media / administration & dosage
  • Contrast Media / pharmacokinetics*
  • Diagnosis, Differential
  • Female
  • Humans
  • Injections, Intravenous
  • Iopamidol / administration & dosage
  • Iopamidol / analogs & derivatives*
  • Iopamidol / pharmacokinetics
  • Logistic Models
  • Lung Neoplasms / diagnostic imaging*
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Radiation Dosage
  • Sensitivity and Specificity
  • Solitary Pulmonary Nodule / diagnostic imaging*
  • Statistics, Nonparametric
  • Tomography, Spiral Computed*


  • Contrast Media
  • iomeprol
  • Iopamidol