Comparison of dynamic susceptibility contrast (DSC) using gadolinium and iron-based contrast agents in high-grade glioma at high-field MRI

PURPOSE

To compare DSC-MRI using Gadolinium (GBCA) and Ferumoxytol (FBCA) in high-grade glioma at 3T and 7T MRI field strengths. We hypothesized that using FBCA at 7T would enhance the performance of DSC, as measured by contrast-to-noise ratio (CNR).

METHODS

Ten patients (13 lesions) were assigned to 3T (6 patients, 6 lesions) or 7T (4 patients, 7 lesions). All lesions received 0.1 mmol/kg of GBCA on day 1. Ten lesions (4 at 3T and 6 at 7T) received a lower dose (0.6 mg/kg) of FBCA, followed by a higher dose (1.0-1.2 mg/kg), while 3 lesions (2 at 3T and 1 at 7T) received only a higher dose on Day 2. CBV maps with leakage correction for GBCA but not for FBCA were generated. The CNR and normalized CBV (nCBV) were analyzed on enhancing and non-enhancing high T2W lesions.

RESULTS

Regardless of FBCA dose, GBCA showed higher CNR than FBCA at 7T, which was significant for high-dose FBCA (p < .05). Comparable CNR between GBCA and high-dose FBCA was observed at 3T. There was a trend toward higher CNR for FBCA at 3T than 7T. GBCA also showed nCBV twice that of FBCA at both MRI field strengths with significance at 7T.

CONCLUSION

GBCA demonstrated higher image conspicuity, as measured by CNR, than FBCA on 7T. The stronger T2* weighting realized with higher magnetic field strength, combined with FBCA, likely results in more signal loss rather than enhanced performance on DSC. However, at clinical 3T, both GBCA and FBCA, particularly a dosage of 1.0-1.2 mg/kg (optimal for perfusion imaging), yielded comparable CNR.

Mismatch Repair Deficient Glioma with Spatially Distinct IDH-mutant and IDH-Wildtype Components Arising in the Setting of Lynch Syndrome

Mutations in MLH1, MSH2, PMS2, and MSH6 compromise DNA mismatch repair mechanisms and in the heterozygous state predispose patients to Lynch syndrome which is typified by reproductive and gastrointestinal solid tumors. Rarely, pathologic aberrations in these genes may underlie the development of primary central nervous system tumors. We present a report of an adult female with a multicentric, infiltrative supratentorial glioma involving the left anterior temporal horn and left precentral gyrus. Surgical treatment and neuropathological/molecular evaluation of these lesions revealed discordant IDH status and histologic grade at spatially distinct disease sites. A frameshift alteration within the MLH1 gene (p.R217fs*12, c.648delT) was identified in both lesions and subsequently identified in constitutional tissue, consistent with Lynch syndrome. Despite distinct histopathologic features and divergent IDH status of the patient's tumors, the molecular findings suggest that both sites of intracranial neoplasia may have developed as a consequence of underlying constitutional mismatch repair deficiency. This case illustrates the importance of characterizing the genetic profile of multicentric gliomas and highlights the oncogenic potential of germline mismatch repair gene mutations within the central nervous system.