Evaluation of plaque detection and optimum time of enhancement in acute attack multiple sclerosis after contrast injection

Detection of pathological contrast enhancement with synthetic brain imaging from quantitative multiparametric MRI

BACKGROUND AND PURPOSE

We aimed to test whether synthetic T1-weighted imaging derived from a post-contrast Quantitative Transient-state Imaging (QTI) acquisition enabled revealing pathological contrast enhancement in intracranial lesions.

METHODS

The analysis included 141 patients who underwent a 3 Tesla-MRI brain exam with intravenous contrast media administration, with the post-contrast acquisition protocol comprising a three-dimensional fast spoiled gradient echo (FSPGR) sequence and a QTI acquisition. Synthetic T1-weighted images were generated from QTI-derived quantitative maps of relaxation times and proton density. Two neuroradiologists assessed synthetic and conventional post-contrast T1-weighted images for the presence and pattern of pathological contrast enhancement in intracranial lesions. Enhancement volumes were quantitatively compared.

RESULTS

Using conventional imaging as a reference, synthetic T1-weighted imaging was 93% sensitive in revealing the presence of contrast enhancing lesions. The agreement for the presence/absence of contrast enhancement was almost perfect both between readers (k = 1 for both conventional and synthetic imaging) and between sequences (k = 0.98 for both readers). In 91% of lesions, synthetic T1-weighted imaging showed the same pattern of contrast enhancement visible in conventional imaging. Differences in enhancement pattern in the remaining lesions can be due to the lower spatial resolution and the longer acquisition delay from contrast media administration of QTI compared to FSPGR. Overall, enhancement volumes appeared larger in synthetic imaging.

CONCLUSIONS

QTI-derived post-contrast synthetic T1-weighted imaging captures pathological contrast enhancement in most intracranial enhancing lesions. Further comparative studies employing quantitative imaging with higher spatial resolution is needed to support our data and explore possible future applications in clinical trials.

Delayed phases of contrast MRI, can it be valuable in multiple sclerosis active phase diagnosis?

Background:

Observing the enhancing plaques in magnetic resonance imaging (MRI) is one of the most valuable diagnostic modalities in confirming the diagnosis of multiple sclerosis (MS), its recurrence and for better detection of active disease. Since active lesions discovery can improve designating diffusion in time diagnosis of MS and controlling disease activity, and there is not any definite time for delay image acquisition, therefore, the aim of the current study was to evaluate the enhancement of MS plaques in different delayed phases.

Methods:

In this interventional study, after receiving written consent, 40 MS patients with at least one enhancing plaque in a previous MRI were evaluated in Babol Ayatollah Rouhani Hospital. Gadolinium was injected to all patients at the dose of 0.1 mg/kg, and MRI was taken at 5 and 15 minutes. The results were analyzed using SPSS 23. A p<0.05 was considered as significant level.

Results:

The mean of plaque signal intensity was 1190.20 and 1349.60 at 5 and 15 min, respectively, and this difference was significant (p<0.001). Moreover, the mean of plaque total size was 5.16 cm and 7.04 cm at 5 and 15 min with significant difference, respectively (p<0.001). The mean of plaque number was 1.92 and 2.58 at 5 and 15 min, respectively, which was significantly different (P<0.001).

Conclusion:

The results indicated improvement in detection of MS plaques in images taken in the delayed phase compared to those in the early phase. The plaque intensity, size and number were significantly higher in the delayed phase (15 min), than early phase (5 min).

Improving acute demyelinating lesion detection: which T1-weighted magnetic resonance acquisition is more sensitive to gadolinium enhancement?

OBJECTIVE

Because of the need for a standardized and accurate method for detecting multiple sclerosis (MS) inflammatory activity, different magnetic resonance (MR) acquisitions should be compared in order to choose the most sensitive sequence for clinical routine. To compare the sensitivity of a T1-weighted image to a single dose of gadolinium (Gd) administration both with and without magnetization transfer to detect contrast enhancement in active demyelinating focal lesions.

METHODS

A sample of relapsing-remitting MS patients were prospectively examined separately by two neuroradiologists using a 1.5 Tesla scanner. The outcome parameters were focused on Gd-enhancement detection attributed to acute demyelination. All MR examinations with at least one Gd-enhancing lesion were considered positive (MR+) and each lesion was analyzed according to its size and contrast ratio.

RESULTS

Thirty-six MR examinations were analyzed with a high inter-observer agreement for MR+ detection (k coefficient > 0.8), which was excellent for the number of Gd-enhancing lesions (0.91 T1 spin-echo (SE), 0.88 T1 magnetization transfer contrast (MTC) sequence and 0.99 magnetization-prepared rapid acquisition with gradient-echo (MPRAGE). Significantly more MR+ were reported on the T1 MTC scans, followed by the T1 SE, and MPRAGE scans. Confidently, the T1 MTC sequence demonstrated higher accuracy in the detection of Gd-enhancing lesions, followed by the T1 SE and MPRAGE sequences. Further comparisons showed that there was a statistically significant increase in the contrast ratio and area of Gd-enhancement on the T1 MTC images when compared with both the SE and MPRAGE images.

CONCLUSION

Single-dose Gd T1 MTC sequence was confirmed to be the most sensitive acquisition for predicting inflammatory active lesions using a 1.5 T magnet in this sample of MS patients.

MRI in multiple sclerosis: an intra-individual, randomized and multicentric comparison of gadobutrol with gadoterate meglumine at 3 T

OBJECTIVES

To compare contrast effects of gadobutrol with gadoterate meglumine for brain MRI in multiple sclerosis (MS) in a multicentre, randomized, prospective, intraindividual study at 3 T.

METHODS

Institutional review board approval was obtained. Patients with known or suspected active MS lesions were included. Two identical MRIs were performed using randomized contrast agent order. Four post-contrast T1 sequences were acquired (start time points 0, 3, 6 and 9 min). If no enhancing lesion was present in first MRI, second MRI was cancelled. Quantitative (number and signal intensity of enhancing lesions) and qualitative parameters (time points of first and all lesions enhancing; subjective preference regarding contrast enhancement and lesion delineation; global preference) were evaluated blinded.

RESULTS

Seventy-four patients (male, 26; mean age, 35 years) were enrolled in three centres. In 45 patients enhancing lesions were found. Number of enhancing lesions increased over time for both contrast agents without significant difference (median 2 for both). Lesions signal intensity was significantly higher for gadobutrol (p < 0.05 at time points 3, 6 and 9 min). Subjective preference rating showed non-significant tendency in favour of gadobutrol.

CONCLUSION

Both gadobutrol and gadoterate meglumine can be used for imaging of acute inflammatory MS lesions. However, gadobutrol generates higher lesion SI.

KEY POINTS

Contrast-enhanced MRI plays a key role in the management of multiple sclerosis. Different gadolinium-based contrast agents are available. Number of visibly enhancing lesions increases over time after contrast injection. Gadobutrol and gadoterate meglumine do not differ in number of visible lesions. Gadobutrol generates higher signal intensity than gadoterate meglumine.

[Contrast agents in MRI-diagnosis of multiple sclerosis]

Magnetic resonance imaging using contrast agents plays an important role in diagnosis and assessment of treatment efficacy in multiple sclerosis. The development of contrast agents on the basis of gadolinium or iron oxide nanoparticles has potential for diagnosis of pathological foci (tumors, amyloid plaques, inflammation and foci of demyelination or necrosis) in nervous system diseases. Newly developing types of diagnostic substances for visualization of pathological foci in multiple sclerosis are presented in this review.