In vivo MEMRI characterization of brain metastases using a 3D Look-Locker T1-mapping sequence

Abstract

Although MEMRI (Manganese Enhanced MRI) informations were obtained on primary tumors in small animals, MEMRI data on metastases are lacking. Thus, our goal was to determine if 3D Look-Locker T1 mapping was an efficient method to evaluate Mn ions transport in brain metastases in vivo. The high spatial resolution in 3D (156 × 156 × 218 μm) of the sequence enabled to detect metastases of 0.3 mm3. In parallel, the T1 quantitation enabled to distinguish three populations of MDA-MB-231 derived brain metastases after MnCl2 intravenous injection: one with a healthy blood-tumor barrier that did not internalize Mn2+ ions, and two others, which T1 shortened drastically by 54.2% or 24%. Subsequent scans of the mice, enabled by the fast acquisition (23 min), demonstrated that these T1 reached back their pre-injection values in 24 h. Contrarily to metastases, the T1 of U87-MG glioma remained 26.2% shorter for one week. In vitro results supported the involvement of the Transient Receptor Potential channels and the Calcium-Sensing Receptor in the uptake and efflux of Mn2+ ions, respectively. This study highlights the ability of the 3D Look-Locker T1 mapping sequence to study heterogeneities (i) amongst brain metastases and (ii) between metastases and glioma regarding Mn transport.

Compressed‐Sensing MP2RAGE sequence: Application to the detection of brain metastases in mice at 7T

“…Even though the MP2RAGE TR was set at 6.2 s to maximize the acceleration of the MP2RAGE sequence, it could be lengthened to accommodate for imaging at high magnetic fields. Nonetheless, the T 1 of the mouse brain cortex and metastases measured in vivo were similar to the wide range of values found in the literature and were not modified when applying CS. In the case of very small structures, spatial smoothing can occur and affect the measurements.…”

2D multislice MP2RAGE sequence for fast T1 mapping at 7 T: Application to mouse imaging and MR thermometry

“…Fast T 1 mapping of the whole mouse brain with the MS‐MP2RAGE sequence showed the ability to measure T 1 values with low variations along time (less than 1%). The in vivo T 1 values measured with the MS‐MP2RAGE sequence had to be corrected for the inversion efficiency, leading to values within the range found in the existing literature . This study highlights the potential of this sequence to be used during longitudinal studies.…”

Manganese-enhanced MRI (MEMRI) in breast and prostate cancers: Preliminary results exploring the potential role of calcium receptors

“…Previous in vitro studies demonstrated the link between CaSR and TRPV6, where TRPV6 action induces calcium ions entry in CaSR [39,40]. The potential leading role of calcium receptors in manganese uptake has also been recently demonstrated by Castets CR et al, in a study where breast or glioma cancer cells lines pre-treated with Mn 2+ and then incubated with calcium blockers enabled to retain Mn 2+ ions into the cells [41].…”