Quantitative Susceptibility Mapping Differentiates between Blood Depositions and Calcifications in Patients with Glioblastoma

Abstract

ObjectivesThe application of susceptibility weighted imaging (SWI) in brain tumor imaging is mainly used to assess tumor-related “susceptibility based signals” (SBS). The origin of SBS in glioblastoma is still unknown, potentially representing calcifications or blood depositions. Reliable differentiation between both entities may be important to evaluate treatment response and to identify glioblastoma with oligodendroglial components that are supposed to present calcifications. Since calcifications and blood deposits are difficult to differentiate using conventional MRI, we investigated whether a new post-processing approach, quantitative susceptibility mapping (QSM), is able to distinguish between both entities reliably.Materials and MethodsSWI, FLAIR, and T1-w images were acquired from 46 patients with glioblastoma (14 newly diagnosed, 24 treated with radiochemotherapy, 8 treated with radiochemotherapy and additional anti-angiogenic medication). Susceptibility maps were calculated from SWI data. All glioblastoma were evaluated for the appearance of hypointense or hyperintense correlates of SBS on the susceptibility maps.Results43 of 46 glioblastoma presented only hyperintense intratumoral SBS on susceptibility maps, indicating blood deposits. Additional hypointense correlates of tumor-related SBS on susceptibility maps, indicating calcification, were identified in 2 patients being treated with radiochemotherapy and in one patient being treated with additional anti-angiogenic medication. Histopathologic reports revealed an oligodendroglial component in one patient that presented calcifications on susceptibility maps.ConclusionsQSM provides a quantitative, local MRI contrast, which reliably differentiates between blood deposits and calcifications. Thus, quantitative susceptibility mapping appears promising to identify rare variants of glioblastoma with oligodendroglial components non-invasively and may allow monitoring the role of calcification in the context of different therapy regimes.

Magnetic resonance susceptibility weighted imaging in neurosurgery: current applications and future perspectives

“…34 SWI can effectively demonstrate intratumoral calcification as well, 23,70,76,112,118 with hypointensity seen on SW images, which correlates with CT findings (Fig. 4).…”

“…7,49 By monitoring changes in pre-and postrecanalization of the CVS, SWI can detect differences in CVS prominence before and after occlusion. 7 Thus, an equal CVS postrecanalization (that is, the appearance of similar veins in both hemispheres) is suggestive of a good clinical outcome, whereas a less prominent CVS (that is, veins in an occluded hemisphere are less prominent than veins in However, most studies 20,23,88 have focused on lesion detection in sporadic or familial cerebral cavernous malformations (CCMs), making it difficult to assess the sensitivity of SWI in detecting VMs other than CCMs.…”

“…52,53 Moreover, in more complex cases, SWI can help diagnose specific high-flow VMs, such as arteriovenous malformations (AVMs; Fig. 9), 53 and low-flow VMs, including CCM, 20,23,88 brain capillary telangiectasia, 28 or Sturge-Weber syndrome. 48,110 Most importantly, the findings from SWI, especially at ultrahigh fields (that is, 7 T), 29 are shown to correlate with histopathological studies.…”

Intracranial Calcifications and Hemorrhages: Characterization with Quantitative Susceptibility Mapping

“…GRE phase imaging has been reported to be useful for differentiating calcifications from hemorrhages (3,8,11). Recently, it has been suggested that QSM can enable the differentiation of diamagnetic calcifications from paramagnetic hemorrhages (9,17,18). To our knowledge, this study is the first systematic evaluation of the diagnostic accuracy of QSM and comparison between QSM and GRE phase imaging in the assessment of calcifications and hemorrhages.…”

“…Chen et al (13,15,16) and has been suggested for differentiating diamagnetic calcifications from paramagnetic hemorrhages (9,17,18). We performed this study to compare GRE phase imaging and QSM in the detection of intracranial calcifications and hemorrhages.…”