T1-weighted Grey Matter Signal Intensity Alterations After Multiple Administrations of Gadobutrol in Patients with Multiple Sclerosis, Referenced to White Matter

Gadolinium Contrast Agent Deposition in Children

Over the past few years, a large number of studies have evidenced increased signal intensity in the deep brain nuclei on unenhanced T1-MRI images achieved by the application of gadolinium-based contrast agents (GBCAs). The deposition of gadolinium in the brain, bone, and other tissues following administration of GBCAs has also been confirmed in histological studies in rodents and in necropsy studies in adults and children. Given the distinct physiological characteristics of children, this review focuses on examining the current research on gadolinium deposition in children, particularly studies utilizing novel methods and technologies. Furthermore, the article compares safety research findings of linear GBCAs and macrocyclic GBCAs in children, with the aim of offering clinicians practical guidance based on the most recent research outcomes. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 2.

Brain deposition of gadobutrol in children-a cross-sectional and longitudinal MRI T1 mapping study

OBJECTIVES

Depositions of linear gadolinium-based MRI contrast agents are readily visible in T1-weighted MRIs of certain brain regions in both adults and children. Macrocyclic contrast agents such as gadobutrol have so far escaped detection by qualitative MRI in children. This study aimed to assess whether there is evidence for deposition of gadobutrol in children using quantitative T1 mapping.

METHODS

This retrospective study included patients, naive to other gadolinium-based contrast agents than gadobutrol, who had received gadobutrol as part of a clinically indicated MRI. For each patient, T1 relaxation times at 3 T were measured using single-shot T1 mapping at two time points. In each of six brain regions, age-adjusted T1 relaxation times were correlated with a number of previous gadobutrol administrations. To combine interindividual, cross-sectional effects with intraindividual, longitudinal effects, both linear mixed model and generalized additive mixed model were applied.

RESULTS

One hundred four examinations of 52 children (age median 11.4, IQR 6.3-15, 26 female) with a median of 7 doses of gadobutrol in the history of their neurological or neurooncological disease were included. After correction for age and indeterminate disease-related effects to T1 time, a negative correlation of T1 time with the number of gadobutrol doses administered was observed in both mixed models in the putamen (beta - 1.65, p = .03) and globus pallidus (beta - 1.98, p = .012) CONCLUSIONS: The results indicate that in children, gadobutrol is deposited in the globus pallidus and putamen.

KEY POINTS

• Previous gadobutrol administration correlates with reduced T1 relaxation times in the globus pallidus and putamen in children. • This decreased T1 might be caused by gadobutrol retention within these gray-matter nuclei.

Analysis of the Gadolinium retention in the Experimental Autoimmune Encephalomyelitis (EAE) murine model of Multiple Sclerosis

OBJECTIVES

The aim of this study is to quantitatively investigate, at the preclinical level, the extent of Gd retention in the CNS, and peripheral organs, of immune-mediated murine models (Experimental Autoimmune Encephalomyelitis -EAE) of Multiple Sclerosis, compared to control animals, upon the injection of gadodiamide. The influence of the Gadolinium Based Contrast Agent administration timing during the course of EAE development is also monitored.

METHODS

EAE mice were injected with three doses (1.2 mmol/kg each) of gadodiamide at three different time points during the EAE development and sacrificed after 21 or 39 days. Organs were collected and the amount of Gd was quantified through Inductively Coupled Plasma-Mass Spectrometry. Transmission electron microscopy (TEM) and MRI techniques were applied to add spatial and qualitative information to the obtained results.

RESULTS

In the spinal cord of EAE group, 21 days after gadodiamide administration, a significantly higher accumulation of Gd occurred. Conversely, in the encephalon, a lower amount of Gd retention was reached, even if differences emerged between EAE and controls mice. After 39 days, the amounts of retained Gd markedly decreased. TEM validated the presence of Gd in CNS. MRI of the encephalon at 7.1T did not highlight any hyper intense region.

CONCLUSION

In the spinal cord of EAE mice, which is the mostly damaged region in this specific animal model, a preferential but transient accumulation of Gd is observed. In the encephalon, the Gd retention could be mostly related to inflammation occurring upon immunization rather than to demyelination.

No Changes in T1 Relaxometry After a Mean of 11 Administrations of Gadobutrol

OBJECTIVES

Quantitative T1 relaxometry is the benchmark in imaging potential gadolinium deposition and known to be superior to semiquantitative signal intensity ratio analyses. However, T1 relaxometry studies are rare, commonly limited to a few target structures, and reported results are inconsistent.We systematically investigated quantitative T1 relaxation times (qT1) of a variety of brain nuclei after serial application of gadobutrol.

MATERIALS AND METHODS

Retrospectively, qT1 measurements were performed in a patient cohort with a mean number of 11 gadobutrol applications (n = 46) and compared with a control group with no prior gadolinium-based contrast agent administration (n = 48). The following target structures were evaluated: dentate nucleus, globus pallidus, thalamus, hippocampus, putamen, caudate, amygdala, and different white matter areas. Subsequently, multivariate regression analysis with adjustment for age, presence of brain metastases and previous cerebral radiotherapy was performed.

RESULTS

No assessed site revealed a significant correlation between qT1 and number of gadobutrol administrations in multivariate regression analysis. However, a significant negative correlation between qT1 and age was found for the globus pallidus as well as anterior and lateral thalamus (P < 0.05 each).

CONCLUSIONS

No T1 relaxation time shortening due to gadobutrol injection was found in any of the assessed brain structures after serial administration of 11 doses of gadobutrol.

Does the proteasome inhibitor bortezomib sensitize to DNA-damaging therapy in gastroenteropancreatic neuroendocrine neoplasms? - A preclinical assessment in vitro and in vivo

BACKGROUND

Well-differentiated gastroenteropancreatic neuroendocrine neoplasms are rare tumors with a slow proliferation. They are virtually resistant to many DNA-damaging therapeutic approaches, such as chemo- and external beam therapy, which might be overcome by DNA damage inhibition induced by proteasome inhibitors such as bortezomib.

METHODS AND RESULTS

In this study, we assessed several combined treatment modalities in vitro and in vivo. By cell-based functional analyses, in a 3D in ovo and an orthotopic mouse model, we demonstrated sensitizing effects of bortezomib combined with cisplatin, radiation and peptide receptor radionuclide therapy (PRRT). By gene expression profiling and western blot, we explored the underlying mechanisms, which resulted in an impaired DNA damage repair. Therapy-induced DNA damage triggered extrinsic proapoptotic signaling as well as the induction of cell cycle arrest, leading to a decreased vital tumor volume and altered tissue composition shown by magnetic resonance imaging and F-18-FDG-PET in vivo, however with no significant additional benefit related to PRRT alone.

CONCLUSIONS

We demonstrated that bortezomib has short-term sensitizing effects when combined with DNA damaging therapy by interfering with DNA repair in vitro and in ovo. Nevertheless, due to high tumor heterogeneity after PRRT in long-term observations, we were not able to prove a therapeutic advantage of bortezomib-combined PRRT in an in vivo mouse model.

Signal changes in enhanced T1-weighted images related to gadolinium retention: A three-time-point imaging study

BACKGROUND AND PURPOSE

Concern has grown about the finding of gadolinium deposits in the brain after administering gadolinium-based contrast agents (GBCAs). The mechanism is unclear, and related questions remain unanswered, including the stability over time. Therefore, we conducted a three-time-point study to explore T1-weighted (W) signal changes in the dentate nucleus (DN) and globus pallidus (GP), after the first, fifth, and tenth injections of either a macrocyclic agent (gadoterate meglumine) or a linear agent (gadobenate dimeglumine).

MATERIALS AND METHODS

For this retrospective, multicenter, longitudinal study, two groups of 18 (gadoterate meglumine) and 19 (gadobenate dimeglumine) patients were identified. The evolution of the signal over time was analyzed using DN/pons (DN/P) and GP/thalamus (GP/T) ratios.

RESULTS

DN/P and GP/T ratios tended to increase after the fifth administration of gadobenate dimeglumine, following by a downward trend. A trend in a decrease in DN/P and GP/T ratios were found after the fifth and tenth administrations of gadoterate meglumine.

CONCLUSION

After exposure to gadobenate dimeglumine, the signal intensity (SI) tended to increase after the fifth injection owing to gadolinium accumulation, however, a SI increase was not found after the tenth administration supporting the hypothesis of a slow elimination of the previously retained gadolinium (wash-out effect) from the brain or of a change in form (by dechelation), causing the signal to fade. No increasing SI was found in the DN and GP after exclusive exposure to gadoterate meglumine, thus confirming its stability. We found, instead, a trend for a significative gadolinium elimination over time.

Spine MRI in Spontaneous Intracranial Hypotension for CSF Leak Detection: Nonsuperiority of Intrathecal Gadolinium to Heavily T2-Weighted Fat-Saturated Sequences

BACKGROUND AND PURPOSE

Spine MR imaging plays a pivotal role in the diagnostic work-up of spontaneous intracranial hypotension. The aim of this study was to compare the diagnostic accuracy of unenhanced spine MR imaging and intrathecal gadolinium-enhanced spine MR imaging for identification and localization of CSF leaks in patients with spontaneous intracranial hypotension.

MATERIALS AND METHODS

A retrospective study of patients with spontaneous intracranial hypotension examined from February 2013 to October 2017 was conducted. Their spine MR imaging was reviewed by 3 blinded readers for the presence of epidural CSF using 3 different sequences (T2WI, 3D T2WI fat-saturated, T1WI gadolinium). In patients with leaks, the presumed level of the leak was reported.

RESULTS

In total, 103 patients with spontaneous intracranial hypotension (63/103 [61%] women; mean age, 50 years) were evaluated. Seventy had a confirmed CSF leak (57/70 [81%] proved intraoperatively), and 33 showed no epidural CSF on multimodal imaging. Intrathecal gadolinium-enhanced spine MR imaging was nonsuperior to unenhanced spine MR imaging for the detection of epidural CSF (P = .24 and .97). All MR imaging sequences had a low accuracy for leak localization. In all patients, only 1 leakage point was present, albeit multiple suspicious lesions were reported in all sequences (mean, 5.0).

CONCLUSIONS

Intrathecal gadolinium-enhanced spine MR imaging does not improve the diagnostic accuracy for the detection of epidural CSF. Thus, it lacks a rationale to be included in the routine spontaneous intracranial hypotension work-up. Heavily T2-weighted images with fat saturation provide high accuracy for the detection of an epidural CSF collection. Low accuracy for leak localization is due to an extensive CSF collection spanning several vertebrae (false localizing sign), lack of temporal resolution, and a multiplicity of suspicious lesions, albeit only a single leakage site is present. Thus, dynamic examination is mandatory before targeted treatment is initiated.

Visible T1-hyperintensity of the dentate nucleus after multiple administrations of macrocyclic gadolinium-based contrast agents: yes or no?

OBJECTIVES

To investigate the appearance of visible dentate nucleus (DN) T1-hyperintensity and quantify changes in DN/pons (DN/P) signal intensity (SI) ratio in MS patients after the exclusive administration of macrocyclic GBCAs.

MATERIALS AND METHODS

One hundred forty-nine patients with confirmed MS were evaluated. Patients received at least two administrations of gadobutrol (n = 63), gadoterate (n = 57), or both (n = 29). Two experienced neuroradiologists in consensus evaluated unenhanced T1-weighted MR images from all examinations in each patient for evidence of visible DN hyperintensity. Thereafter, SI measurements were made in the left and right DN and pons on unenhanced T1-weighted images from the first and last scans. A two-sample t test compared the DN/P SI ratios for patients with and without visible T1-hyperintensity.

RESULTS

Visible T1-hyperintensity was observed in 42/149 (28.2%) patients (19 after gadobutrol only, 15 after gadoterate only, 8 after both), typically at the 4th or 5th follow-up exam at 3-4 years after the initial examination. Significant increases in DN/P SI ratio from first to last examination were determined for patients with visible T1-hyperintensity (0.998 ± 0.002 to 1.153 ± 0.016, p < 0.0001 for gadobutrol; 1.003 ± 0.004 to 1.110 ± 0.014, p < 0.0001 for gadoterate; 1.004 ± 0.011 to 1.163 ± 0.032, p = 0.0004 for both) but not for patients without visible T1-hyperintensity (p > 0.05; all groups).

CONCLUSION

Multiple injections of gadobutrol and/or gadoterate can lead to visible and quantifiable increases in DN/P SI ratio in some patients with MS.