Longitudinal magnetic resonance elastography detects stiff ness changes in post-operative brain tumor patient

Introduction<br/>After surgery and radiochemotherapy, glioma patients are followed with serial magnetic resonance imaging (MRI) scans. The follow-up may be complicated by the occurrence of pseudoprogression, which mimics true disease progression on contrast-enhanced MRI, but requires a different treatment approach. Magnetic resonance elastography (MRE) is a new imaging technique that may be able to discern pseudoprogression from true progression, as it gives quantitative information about tissue stiff ness, similar to manual palpation. Here, we report on the first use of longitudinal MRE in a patient and its potential to detect stiff ness changes in contrast-enhancing lesions during MRI follow-up.<br/>Materials and methods<br/>This is an ongoing case study, where a patient treated for a IDH1 mutated astrocytoma WHO grade 4 has been imaged with the standard MRI protocol and MRE for the past thirteen months. During this period, the patient developed contrast-enhancement adjacent to the operation cavity. Stiff ness is measured in three regions of interest (ROI) in the contrast-enhancing area. ROIs are also delineated in the anatomical locations where contrast enhancement appeared on later scans. Additionally, stiff ness is recorded in normal-appearing white matter in the contralateral hemisphere.<br/>Results<br/>Stiff ness is lower in the contrast-enhancing area compared to the contralateral hemisphere throughout the follow-up period (mean 2.14 kilo pascals (kPa) vs. 3.07 kPa, p &lt; 0.0001). In two ROIs, stiff ness first increases up to the point when the contrast enhancement appears. In the third ROI, stiff ness continuously decreases throughout follow-up. In all ROIs, stiff ness tends to decrease as contrast enhancing area increases.<br/>Conclusion<br/>MRE can detect stiff ness changes prior to and after contrast enhancement develops. Further MRE and follow-up data is needed before drawing conclusions about the nature of the contrast-enhancing area and implementing MRE in the clinical routine.