Predictive value of early DCE and DSC perfusion MRI parameters for midterm clinical outcomes in lung cancer brain metastases treated with stereotactic radiosurgery

Abstract

Purpose: Stereotactic Radiosurgery (SRS) is an effective way of controlling the brain metastasis (BM) of lung carcinoma. This study evaluates the performance of dynamic contrast-enhanced MRI (DCE-MRI) and dynamic susceptibility contrast MRI (DSC-MRI) parameters to distinguish responders from non-responders at midterm follow-up in lung carcinoma BMs.

Methods: Twenty-six patients (mean age 62 ± 10 years) with 54 lung carcinoma BMs (NSCLC 67%, SCLC 33%) underwent SRS. The DCE-MRI and DSC-MRI were performed at baseline and repeated 4-8 weeks post-SRS to predict treatment responses at the midterm follow-up (6-12 months). Midterm outcomes were classified according to RANO-BM criteria as responders (complete response, partial response, or stable disease) or non-responders (progressive disease). Receiver operating characteristic (ROC) analyses evaluated the diagnostic accuracy of individual perfusion parameters and their combinations.

Results: Forty lesions (74%) were responders, while 14 (26%) were non-responders. Progressive lesions showed a mean volume increase of 5.5-fold, whereas responders demonstrated a 60% mean volume reduction. Responders showed significantly lower absolute post-SRS K-trans (median 0.015 vs. 0.035 min⁻¹; p = 0.005), a higher proportional decrease in K-trans from baseline (- 27% vs. +13%; p = 0.017), and lower post-SRS Ve (p = 0.009) compared to non-responders. Absolute post-SRS K-trans had the highest individual predictive accuracy (AUC = 0.75, accuracy = 78%, sensitivity = 86%, specificity = 55%). Neither the dynamic change nor post-SRS nCBV alone predicted midterm response; however, combining post-SRS nCBV with K-trans slightly improved predictive performance (AUC = 0.76, accuracy = 79%).

Conclusion: Early post-SRS absolute K-trans is the best perfusion parameter for predicting midterm response in lung carcinoma BMs. DSC-MRI parameters alone offer limited predictive value.

Keywords: Brain metastasis; Lung carcinoma; Perfusion MRI; Stereotactic radiosurgery.

Fig. 1

Lesion-based progression-free survival after the SRS. No difference was noted in the response status of the cerebral metastasis based on tumor subtype, (p = 0.46). SCLC, Small cell lung carcinoma; NSCLC, non-small cell lung carcinoma

Fig. 2

Representative cases of stereotactic radiosurgery (SRS) responder and non-responder brain metastases (BMs) from lung carcinoma, demonstrating multiparametric MRI findings at pre- and early post-SRS timepoints. (a) In the responder case, a 66-year-old patient with lung adenocarcinoma had a solid metastasis located in the right deep parietal white matter (precuneus). (b) Pre-SRS K-trans was measured at 0.058 min⁻¹, and (c) the normalized cerebral blood volume (nCBV) was 3.4 with the same region of interest (ROI). (d) Four weeks after SRS, there was a marked reduction in lesion size and perilesional edema. (e) The early post-SRS K-trans decreased to 0.042 min⁻¹, corresponding to a 28% reduction. (f) nCBV of BMs decreased to 2.9 at the early post-SRS stage. (g) At the 28-week midterm follow-up, the lesion had completely resolved with regressed surrounding edema consistent with a complete treatment response. (h) In the non-responder case, a 55-year-old patient with small cell lung carcinoma had a solid metastasis in the right superior temporal gyrus. (i) Pre-SRS K-trans of the BMs was 0.121 min⁻¹, and (j) the corresponding nCBV was 3.9 with the same ROI. (k) Early post-SRS imaging showed a slight increase in lesion size, (l) with a persistently high K-trans of 0.125 min⁻¹, and (m) a modest reduction in nCBV to 3.2. (n) At the 24-week midterm follow-up, the lesion is enlarged further with prominent surrounding edema, necessitating an additional SRS session. In this non-responder case, persistently high K-trans despite a mild nCBV decrease suggested treatment resistance and poor response to SRS

Fig. 3

Lesion-level illustration of dynamic changes in K-trans values following stereotactic radiosurgery (SRS) for brain metastases (BMs) from lung carcinoma. Each line represents an individual BM, depicting the K-trans change from pre-SRS to early post-SRS evaluation. The responder group (n = 40) demonstrated a mean K-trans reduction of 27% ± 50%, whereas the non-responder (n = 14) group showed a mean increase of 13% ± 52% (p = 0.017)

Fig. 4

Volumetric changes in lung carcinoma cerebral metastases stratified by K-trans alterations 4–8 weeks after SRS. Tumors with increased K-trans showed significantly higher volumes at the midterm time point compared to those with decreased K-trans (p = 0.004)

Fig. 5

Receiver operating characteristics (ROC) analysis for the significant parameters at 4–8 weeks after the SRS in terms of midterm response of lung carcinoma cerebral metastasis. (A) ROC curves of absolute post-SRS K-trans, V_e, nCBV value, and proportion of K-trans change from the pretreatment stage. (B) ROC analysis of combined tests between the significant DCE-MRI and DSC-MRI parameters