Abstract
BACKGROUND: Percentagewise quantification (PQ) of intratumoral susceptibility signals (ITSS) on susceptibility weighted imaging (SWI) serves as an objective and quantitative method capable of differentiating some primary entities of brain metastases (BMs). We aimed to evaluate PQ of ITSS in BMs of different sizes in three main lung cancer subtypes, and explore if it can improve differential diagnosis in the context of lung cancer. METHODS: In this retrospective study, 213 patients with synchronous BMs from lung cancer [141 adenocarcinoma (AD), 28 squamous cell carcinoma (SCC), 44 small cell lung cancer (SCLC)], who underwent routine brain contrast-enhanced magnetic resonance imaging (MRI) and contrast-enhanced SWI (CE-SWI), were enrolled. The BMs were delineated on CE-SWI by mutual consent of two radiologists. All voxels within the lesion and voxels presenting values lower than those of the ventricular system were evaluated separately, and then ITSS were percentagewise calculated. The incidence of PQ <1% (no ITSS) and PQ of ITSS in Group 1 (micrometastases, ≤0.125 cm(3)), Group 2 (middle metastases, 0.125 cm(3)< size <27 cm(3)) and Group 3 (macrometastases, ≥27 cm(3)) from the three subtypes of lung cancer were compared. RESULTS: The incidence of no ITSS in Group 1 was higher than that in Groups 2 and 3 in the three subtypes of lung cancer. BMs in Group 2 and Group 3 had higher PQ of ITSS than those in Group 1. In Group 3, PQ of ITSS in AD was higher than that in SCC (P=0.016) and in SCLC (P=0.010), while there was no difference between SCC and SCLC (P=0.921). Diagnostic performance of PQ of ITSS in Group 3 was good [area under the receiver operating characteristic curve (AUC) =0.81; 95% confidence interval (CI): 0.64, 0.98] to discriminate AD from non-AD. At a cut off value of 6.68%, the sensitivity and specificity for differentiation of AD and non-AD were 0.92 and 0.71, respectively. CONCLUSIONS: PQ of ITSS can contribute to the non-invasive characterization of BMs from the three subtypes of lung cancer. The larger lesions (middle metastases and macrometastases) of BMs were more likely to have positive ITSS and exhibited higher PQ of ITSS than small ones (micrometastases), and macrometastases of AD and non-AD can be distinguished with high sensitivity and specificity.