Purpose: It has been reported that intravenously administered gadolinium-based contrast agents (IV-GBCAs) leak into the cerebrospinal fluid (CSF) even in healthy subjects. The purpose of this study was to evaluate GBCA leakage from the cortical veins in patients with delayed imaging after IV-GBCA.

Materials and Methods: There are two parts of retrospective study. In the first part, we reviewed six patients with suspected endolymphatic hydrops (EH) who received a single dose of IV-GBCA (37–58 years old). The 3D-real inversion recovery images were obtained prior to the contrast administration as well as 5 min and 4 h after IV-GBCA. Leakage from the cortical veins to the CSF was graded as positive if enhancement around the cortical veins at 5 min was observed and had further spread into the CSF at 4 h after IV-GBCA.

In the second part of this study, we reviewed 21 patients with suspected EH (17–69 years old). Images were obtained only at 4 h after IV-GBCA. The number of slices (NOS) with a positive GBCA leakage from the cortical veins was counted. The correlation of the NOS with age, gender, and degree of EH was evaluated by Spearman’s rank correlation coefficient.

Results: In the first part of the study, the GBCA leakage from the cortical veins was positive in all patients. In the second part of the study, the GBCA leakage from the cortical veins was seen in all older patients (above 37 years old), but not in the five younger patients (younger than 37 years old). The NOS correlated significantly only with age (r = 0.755, P < 0.01), but not with gender or degree of EH.

Conclusion: IV-GBCA leaks from the cortical veins into the surrounding CSF. The leakiness of the cortical veins significantly correlated with age, but not with gender or degree of EH.

Purpose: To compare four free-breathing scan techniques for gadoxetic acid-enhanced hepatobiliary phase imaging with conventional breath-hold scans.

Materials and Methods: Gadoxetic acid-enhanced hepatobiliary phase imaging with six image acquisition sets performed in 50 patients. Image acquisition sets included fat-suppressed 3D T₁-weighted turbo field echo with free-breathing pseudo-golden-angle radial stack-of-stars (FBRS) acquisition, FBRS with track (FBRS_T), FBRS with gate and track (FBRS_G&T), thin-slice FBRS with gate and track (thin-slice FBRS_G&T), free-breathing Cartesian acquisition (Cartesian_FB), and breath-hold Cartesian acquisition (Cartesian_BH). Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and image quality compared to the six-image acquisition sets.

Results: Signal-to-noise ratio and CNR were significantly higher in FBRS, FBRS_T, FBRS_G&T, and thin-slice FBRS_G&T than in Cartesian_FB and Cartesian_BH (P < 0.001). Based on sharpness, motion artifacts, visibility of intrahepatic vessels, and overall image quality, thin-slice FBRS_G&T had the highest image quality followed by Cartesian_BH and FBRS_G&T (P < 0.001). Severe motion artifacts were observed in 25 patients in Cartesian_FB and three patients in Cartesian_BH, whereas image quality remained above the acceptable range in FBRS_G&T, FBRS_T, FBRS, and thin-slice FBRS_G&T in all cases.

Conclusion: Thin-slice FBRS_G&T demonstrated excellent image quality compared with conventional Cartesian_BH in gadoxetic acid-enhanced hepatobiliary phase imaging. It can be apply to supplemental sequences of patients with unstable breath holding.

Purpose: Identifying plaque components such as intraplaque hemorrhage, lipid rich necrosis, and calcification is important to evaluate vulnerability of carotid atherosclerotic plaque; however, conventional vessel wall MR imaging may fail to discriminate plaque components. We aimed to evaluate the components of plaques using quantitative susceptibility mapping (QSM), a newly developed post-processing technique to provide voxel-based quantitative susceptibilities.

Methods: Seven patients scheduled for carotid endarterectomy were enrolled. Magnitude and phase images of five-echo 3D fast low angle shot (FLASH) were obtained using a 3T MRI, and QSM was calculated from the phase images. Conventional carotid vessel wall images (black-blood T₁-weighted images [T₁WI], T₂-weighted images [T₂WI], proton-density weighted images [PDWI], and time-of-flight images [TOF]) were also obtained. Pathological findings including intraplaque hemorrhage, calcification, and lipid rich necrosis at the thickest plaque section were correlated with relative susceptibility values with respect to the sternocleidomastoid muscle on QSM. On conventional vessel wall images, the contrast–noise ratio (CNR) between the three components and sternocleidomastoid muscle was measured respectively. Wilcoxon signed-rank test analyses were performed to assess the relative susceptibility values and CNR.

Results: Pathologically, lipid rich necrosis was proved in all of seven cases, and intraplaque hemorrhage in five of seven cases. Mean relative susceptibility value of hemorrhage was higher than lipid rich necrosis unexceptionally (P = 0.0313). There were no significant differences between CNR of hemorrhage and lipid rich necrosis on all sequences. In all six cases with plaque calcification, susceptibility value of calcification was significantly lower than lipid rich necrosis unexceptionally (P = 0.0156). There were significant differences between CNRs of lipid rich necrosis and calcification on T₁WI, PDWI, TOF (P < 0.05).

Conclusion: QSM of carotid plaque would provide a novel quantitative MRI contrast that enables reliable differentiation among intraplaque hemorrhage, lipid rich necrosis, and calcification, and be useful to identify vulnerable plaques.

Purpose: To investigate whether the genu of the corpus callosum is involved in patients with clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) type I.

Methods: Twenty-three cases of clinically confirmed MERS I were analyzed retrospectively, and MRI features of the lesion were observed. The apparent diffusion coefficient (ADC) values of the same region of interests in lesions at the splenium and genu of the corpus callosum were measured before and after treatment (i.e., four groups), and the average ADC values were calculated. Paired t-tests were used to compare the ADC values of lesions in the splenium and genu before and after treatment. Independent sample t-tests were used to compare the values in the splenium and genu after treatment.

Results: The mean ADC values of the splenium before and after treatment were 0.448 ± 0.124 and 0.790 ± 0.070 × 10⁻³ mm²/s, respectively, showing significant difference (P < 0.01). The mean ADC values in the genu before and after treatment were 0.783 ± 0.067 and 0.829 ± 0.070 × 10⁻³ mm²/s, respectively, also showing significant difference (P < 0.01). There was no significant difference in the ADC values between the splenium and genu after treatment (P > 0.05).

Conclusion: The genu showed a slight restriction in diffusion in the acute stage of type I MERS. After treatment, this diffusion restriction diminished as it typically does in the splenium. Our results indicate that the pathology in MERS extends well beyond the visible lesions.

Magnetic resonance fingerprinting (MRF) is a promising framework that allows the quantification of multiple magnetic resonance parameters with a single scan. MRF using fast imaging with steady-state precession (MRF-FISP) has robustness to off-resonance artifacts and has many applications in inhomogeneous fields. However, the spoiler gradient used in MRF-FISP is sensitive to diffusion motion, and may lead to quantification errors when the spoiler moment increases. In this study, we examined the effect of the diffusion weighting in MRF-FISP caused by spoiler gradients. The T₂ relaxation times were greatly underestimated when large spoiler moments were used. The T₂ underestimation was prominent for tissues with large values of T₂ and diffusion coefficients. The T₂ bias was almost independent of the apparent diffusion coefficient (ADC) and T₂ values when the ADC map was measured and incorporated into the matching process. These results reveal that the T₂ underestimation resulted from the diffusion weighting caused by the spoiler gradients.