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Proposal to utilize simplified Swensen protocol in diagnosis of isolated pulmonary nodule
Sergio Marrone Ribeiro1, Raul Lopes Ruiz, Hugo Hyung Bok Yoo
1Department of Tropical Diseases and Diagnostic Imaging, Botucatu Medical School, UNESP - Univ Estadual Paulista, Botucatu, Sao Paulo.
Background:
The problem of diagnosing whether a solitary pulmonary nodule is benign or malignant is even greater in developing countries due to a higher prevalence of infectious diseases. These infections generate a large number of patients who are generally asymptomatic and with a pulmonary nodule that cannot be accurately defined as having benign or malignant etiology.
Purpose:
To verify the percentages of benign versus malignant non-calcified nodules, the length of time after contrast agent injection is spiral computed tomography (CT) most sensitive and specific, and whether three postcontrast phases are necessary.
Material And Methods:
We studied 23 patients with solitary pulmonary nodules identified on chest radiographs or CT. Spiral scans were obtained with Swensen protocol, but at 3, 4, and 5 min after contrast injection onset. Nodules were classified as benign or malignant by histopathological examination or by an absence or presence of growth after 2 years of follow-up CT.
Results:
Of the 23 patients studied, 18 (78.2%) showed a final diagnosis of benign and five (21.7%) malignant nodules. Despite the small sample size, we obtained results similar to those of Swensen et al., with 80.0% sensitivity, 55.5% specificity, and 60.8% accuracy. Four minutes gave the greatest mean enhancement in both malignant and benign lesions.
Conclusion:
Small non-calcified benign nodules were much more frequent than malignant nodules. The best time for dynamic contrast-enhanced CT density analysis was 4 min postcontrast. As well as saving time and money, this simplified Swensen protocol with only precontrast and 4 min postcontrast phases also reduces patient exposure to ionizing radiation.
Insights
Benign non-calcified pulmonary nodules are more common than malignant ones. Dynamic contrast-enhanced CT at 4 minutes postcontrast offers optimal sensitivity and specificity for nodule diagnosis, simplifying protocols and reducing radiation exposure.
Area of Science:
- Radiology
- Oncology
- Pulmonology
Background:
- Diagnosing solitary pulmonary nodules is challenging, particularly in developing countries with high infectious disease prevalence.
- Infectious diseases can cause asymptomatic pulmonary nodules with unclear benign or malignant etiology.
Purpose of the Study:
- To determine the prevalence of benign versus malignant non-calcified nodules.
- To identify the optimal timing for spiral computed tomography (CT) after contrast injection for nodule diagnosis.
- To assess the necessity of three postcontrast phases.
Main Methods:
- Twenty-three patients with solitary pulmonary nodules underwent spiral CT scans at 3, 4, and 5 minutes postcontrast.
- Nodule classification was based on histopathology or 2-year follow-up CT for growth.
- The Swensen protocol was adapted for timing analysis.
Main Results:
- 18 nodules (78.2%) were benign, and 5 (21.7%) were malignant.
- Sensitivity was 80.0%, specificity 55.5%, and accuracy 60.8%.
- Maximum mean enhancement for both benign and malignant lesions occurred at 4 minutes postcontrast.
Conclusions:
- Small, non-calcified benign nodules are more frequent than malignant ones.
- The optimal time for dynamic contrast-enhanced CT density analysis is 4 minutes postcontrast.
- A simplified protocol (precontrast and 4 min postcontrast) saves time, cost, and reduces radiation exposure.
