Korean J Radiol.  2008 Oct;9(5):401-408. 10.3348/kjr.2008.9.5.401.

Solitary Pulmonary Nodule on Helical Dynamic CT Scans: Analysis of the Enhancement Patterns Using a Computer-Aided Diagnosis (CAD) System

• Choi EJ
• Jin GY
• Han YM
• Lee YS
• Kweon KS

• KMID: 1385397
• DOI: http://doi.org/10.3348/kjr.2008.9.5.401

Abstract

OBJECTIVE
We wanted to investigate the usefulness of a computer-aided diagnosis (CAD) system in assisting radiologists to diagnosis malignant solitary pulmonary nodules (SPNs), as compared with diagnosing SPNs with using direct personal drawing. MATERIALS AND METHODS: Forty patients with SPNs were analyzed. After the pre-contrast scan was performed, an additional ten series of post-contrast images were obtained at 20-second intervals. Two investigators measured the attenuation values of the SPNs: a radiologist who drew the regions of interest (ROIs), and a technician who used a CAD system. The Bland and Altman plots were used to compare the net enhancement between a CAD system and direct personal drawing. The diagnostic characteristics of the malignant SPNs were calculated by considering the CAD and direct personal drawing and with using Fisher's exact test. RESULTS: On the Bland and Altman plot, the net enhancement difference between the CAD system and direct personal drawing was not significant (within +/- 2 standard deriation). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of diagnosing malignant SPNs using CAD was 92%, 85%, 75%, 96% and 88%, respectively. The sensitivity, specificity, PPV, NPV and accuracy of diagnosing malignant SPNs using direct drawing was 92%, 89%, 79%, 92% and 88%, respectively. CONCLUSION: The CAD system was a useful tool for diagnosing malignant SPNs.

Keyword

Computers, diagnosis aid; Lung neoplasms, diagnosis; Lung neoplasms, nodule

MeSH Terms

Adult
Aged
Contrast Media
Diagnosis, Computer-Assisted/*methods
Diagnosis, Differential
Female
Humans
Iohexol/analogs & derivatives/diagnostic use
Lung Neoplasms/*radiography
Male
Middle Aged
Predictive Value of Tests
Radiographic Image Enhancement/*methods
Retrospective Studies
Sensitivity and Specificity
Solitary Pulmonary Nodule/*radiography
Tomography, Spiral Computed/*methods

Figure

• 

  Fig. 1 Methods of enhancement pattern analysis using CAD system. A. Before intravenously injecting contrast medium, series of images was obtained throughout entire nodule along z-axis, and additional ten sets (20s, 40s, 60s, 80s, 120s, 140s, 160s, 180s, 240s and 300s) of images were obtained at 20-second intervals over 5-minute period after injecting contrast medium. Region of interest covered approximately full diameter of nodule and single radiologist directly drew region of interest. B. Solitary pulmonary nodule was region of interest drawn by expert technician with using CAD system.

• 

  Fig. 2 Bland and Altman plot showing difference between using CAD system and direct personal drawing. A. Difference in peak enhancement between using CAD system and direct personal drawing. B. Difference in net enhancement between using CAD system and direct personal drawing. X-axis represented average values of using CAD system and direct personal drawing while y-axis represented difference in peak enhancement and net enhancement between using CAD system and direct personal drawing. Dashed lines represent mean value of two measurements and lines above and below it represent 95% limits of agreement. Peak enhancement was out of 95% limits of agreement only in one case, while net enhancement was out of 95% limits of agreement in two cases.

• 

  Fig. 3 CT scan of a benign solitary pulmonary nodule with enhancement (≥15 HU wash-in, ≥25 HU washout) in 43-year-old female diagnosed with sclerosing hemangioma by open lung biopsy. Time attenuation curve obtained through nodule for 5 minutes showed similar enhancement patterns of CAD system (short line) and direct personal drawing (long line).

• 

  Fig. 4 CT scan of adenocarcinoma with enhancement (≥15 HU wash-in, 5-25 HU washout) in 72-year-old man. Time attenuation curve obtained through nodule for 5 minutes showed similar enhancement patterns of CAD system (short line) and direct personal drawing (long line).

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