Dynamic MRI of solitary pulmonary nodules: comparison of enhancement patterns of malignant and benign small peripheral lung lesions.
OBJECTIVE
The purpose of this study was to compare the dynamic contrast-enhanced MRI enhancement characteristics of malignant and benign solitary pulmonary nodules.


METHODS
The characteristics of 202 solitary pulmonary nodules (diameter, 1-3 cm; 144 cases of primary lung cancer, 31 cases of focal organizing pneumonia, 15 tuberculomas, 12 hamartomas) were reviewed retrospectively. In all cases dynamic MR images were obtained before and 1, 2, 3, 4, 5, 6, and 8 minutes after bolus injection of gadopentetate dimeglumine. Maximum enhancement ratio, time at maximum enhancement ratio, slope of time-enhancement ratio curves, and washout ratio were assessed. Statistical analyses were performed with the Kruskal-Wallis test with Bonferroni correction, chi-square test, and receiver operating characteristic curves.


RESULTS
For 122 (85%) of 144 primary lung cancers, time at maximum enhancement ratio was 4 minutes or less. For all tuberculomas and hamartomas, time at maximum enhancement ratio was greater than 4 minutes or gradual enhancement occurred without a peak time (p < 0.0001). Lung cancers had different maximum enhancement ratios and slopes than benign lesions (all p < 0.005). With 110% or lower maximum enhancement ratio as a cutoff value, the positive predictive value for malignancy was 92%; sensitivity, 63%; and specificity, 74%. With 13.5%/min or greater slope as a cutoff value, sensitivity, specificity, positive predictive value, and negative predictive value for malignancy were 94%, 96%, 99%, and 74%, respectively.


CONCLUSIONS
Dynamic contrast-enhanced MRI is helpful in differentiating benign from malignant solitary pulmonary nodules. Absence of significant enhancement is a strong predictor that a lesion is benign.
Kono
Rei
R
Department of Radiology, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan.
Fujimoto
Kiminori
K
Terasaki
Hiroshi
H
Müller
Nestor L
NL
Kato
Seiya
S
Sadohara
Junko
J
Hayabuchi
Naofumi
N
Takamori
Shinzo
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001185:Artificial Intelligence; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008175:Lung Neoplasms / Q000145:classification / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010363:Pattern Recognition, Automated / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D003074:Solitary Pulmonary Nodule / Q000145:classification / Q000175:diagnosis*
D003287:Contrast Media; D019786:Gadolinium DTPA