Purpose: There is a significant association between carotid artery (CA) stenosis and atherosclerosis, with those patients often presenting with carotid tortuosity. However, the relationship between atherosclerotic risk factors and carotid tortuosity remains controversial. Previous assessments of tortuosity have predominantly utilized qualitative 2D methods. This retrospective study aimed to quantitatively evaluate the tortuosity of CAs in 3D geometry and to investigate the relationship with atherosclerotic risk factors.

Methods: A total of 168 CAs in 96 patients diagnosed with at least either-side CA stenosis on magnetic resonance angiography (MRA) between 2011 and 2019 were included in this single-center study, following the exclusion of post-treatment CAs and those with poor imaging quality. The 3D geometries of CAs were segmented using MRA and the centerlines were generated. Vascular tortuosity rate (VTR) was calculated as the curved distance divided by the linear distance between the specified 2 points. The relationship between VTRs and 8 atherosclerotic risk factors—age, body mass index, systolic blood pressure, hemoglobin A1c, high-density lipoprotein, total cholesterol (TC), non-fasting serum triglyceride (TG), and Brinkman index—was analyzed.

Results: Higher VTRs were associated with ≥65 years of age, body mass index ≥25 [kg/m²], serum TC ≥220 [mg/dL], and non-fasting serum TG ≥175 [mg/dL] in common CAs, and body mass index ≥25 [kg/m²], and systolic blood pressure ≥140 [mmHg] in internal CAs.

Conclusion: Quantitative assessment of carotid tortuosity revealed significant associations with several atherosclerotic risk factors, including obesity, hypertension, advanced age, and dyslipidemia, suggesting that VTRs may reflect the presence of these risk factors.

Purpose: This study evaluated salivary gland function using MR cine sialography (MRCS) based on the time-spatial labeling inversion pulse (Time-SLIP) technique combined with a deep learning reconstruction–based denoising method (dDLR). Bilateral salivary flow from the submandibular glands (SMGs) and parotid glands (PGs) was visualized, and its correlation with whole-saliva volume was examined.

Methods: Optimal MRCS parameters were identified, and imaging was performed in 11 healthy volunteers. Correlations between salivary flow on MRCS and unstimulated whole-saliva volume (UWS) and stimulated whole-saliva volume (SWS), as well as side-to-side differences, were analyzed. UWS was obtained using the spitting method, and SWS was obtained using the gum-chewing test. Salivary-flow distance was defined as the length from the labeling position to the point where the labeled saliva signal became indistinguishable from background signal. Spearman’s rank correlation coefficients (ρ) were calculated to evaluate the association between whole-saliva volume and MRCS, and Wilcoxon’s signed-rank test was used to assess side-to-side differences.

Results: Correlation coefficients between MRCS and whole-saliva volume were as follows: under unstimulated conditions, SMG ρ = 0.825, PG ρ = −0.05, SMG + PG ρ = 0.802; under stimulated conditions, SMG ρ = 0.606, PG ρ = 0.72, and SMG + PG ρ = 0.820. Strong correlations (ρ > 0.8) were observed for SMG and SMG + PG under unstimulated conditions and for SMG + PG under stimulation. No significant overall side-to-side differences were found except for PG under stimulation (P = 0.016). However, several individuals showed notable side-to-side differences, underscoring the value of bilateral imaging.

Conclusion: Bilateral SMG and PG salivary flows obtained using MRCS with dDLR showed strong correlations with UWS and SWS. These findings suggest that MRCS is a promising noninvasive method for assessing salivary volume and supports both separate and combined evaluation of SMG and PG function.

Purpose: This preliminary study aimed to investigate the agreement in endolymphatic hydrops (EH) grading between high-resolution non-contrast and contrast-enhanced HYDROPS (HYbriD of Reversed image Of Positive endolymph signal and native image of positive perilymph Signal) techniques in the same subjects and to clarify the effect of patient age on the concordance between the 2 methods.

Methods: A retrospective study was performed on 12 patients (24 ears; age range: 24–76 years) suspected of EH, all of whom underwent both non-contrast and 4-hour post-contrast 3T MRI. EH in the cochlea and vestibule was graded by the Nakashima scale. Agreement analyses were assessed using the weighted Cohen’s kappa (κ). Statistical significance, including the difference between Younger (24–54 years) and Older (57–76 years) patient subgroups, was determined via bootstrap analysis.

Results: The overall agreement between non-contrast and contrast-enhanced methods was fair for both the cochlea (κ = 0.343) and vestibule (κ = 0.398). Subgroup analysis revealed a significant age-related difference in vestibular agreement (P = 0.005), showing substantial agreement in the Older group (κ = 0.795) but only slight agreement in the Younger group (κ = 0.113). No significant age-related difference was found for cochlear agreement. Quantitatively, the non-contrast method demonstrated a significantly lower contrast-to-noise ratio compared to the contrast-enhanced method.

Conclusion: The concordance between non-contrast and contrast-enhanced MRI for EH assessment is site- and age-dependent. The substantially higher agreement found in older patients suggests that age-related physiological changes facilitate non-contrast visualization. However, caution is advised when interpreting non-contrast findings in younger patients due to potential risks of vestibular overestimation and cochlear underestimation. Given the preliminary nature and small sample size of this study, further investigations with larger cohorts are necessary to validate these findings and the appropriateness of age-based categorization.

Purpose: To evaluate whether periodically rotated overlapping parallel lines with enhanced reconstruction–diffusion-weighted imaging (PROPELLER-DWI) combined with deep learning–based reconstruction (DLR) improves head and neck DWI, we conducted a primary comparison of PROPELLER-DWI with DLR at varying strengths and without DLR, and a secondary comparison of DLR-processed PROPELLER-DWI with DLR-processed single-shot echo-planar imaging (EPI)-DWI.

Methods: Ten healthy adults (8 males, 2 females) participated in the study. PROPELLER-DWI and single-shot EPI-DWI images were acquired using a 3-Tesla MRI system (Discovery MR750w; GE Healthcare, Waukesha, WI, USA) with various recon deep-learning strength (DLS) values: off (DLS-Off), low (DLS-L), medium (DLS-M), and high (DLS-H). We measured the SNR and contrast ratio on DWI images and value of coefficient of variation (CV) on apparent diffusion coefficient (ADC) maps for a quantitative evaluation. For a qualitative evaluation, we visually evaluated the overall image quality, degree of geometric distortion, and magnetic susceptibility artifacts.

Results: The SNRs for PROPELLER and EPI-DWI improved with the increase in the DLS level, with DLS-H showing a significantly higher SNR than DLS-Off. ADC maps demonstrated lower CVs at higher DLS levels, significantly lower in DLS-H than DLS-Off. The qualitative evaluation revealed that PROPELLER-DWI with DLR (at all DLS levels: -L, -M, and -H) provided significantly better overall image quality than that without DLR. In addition, PROPELLER-DWI demonstrated significantly higher qualitative scores across all evaluation items (i.e., overall image quality, geometric distortion, and magnetic susceptibility artifacts) compared with EPI-DWI.

Conclusion: In head and neck DWI, PROPELLER-based acquisition with DLR enabled the acquisition of visually superior image quality. This approach is clinically useful for the head and neck radiology.

Purpose: To investigate the relationship between the signal intensity (SI) of the entire labyrinthine fluid on non–contrast-enhanced 3D real inversion recovery (3D–real IR) imaging and the endolymphatic volume measured on contrast-enhanced HYDROPS-Mi2 (HYbriD of Reversed image Of Positive endolymph signal and native image of positive perilymph Signal image Multiplied with hT2w MR cisternography) imaging.

Methods: This retrospective study included 37 patients (74 ears) with suspected endolymphatic hydrops (EH). The volume ratio of the endolymphatic space (%EL_vol) was measured on contrast-enhanced HYDROPS-Mi2 images, and the normalized volume-averaged signal intensity (nSI_vol) of the entire labyrinthine fluid was measured on non–contrast-enhanced 3D–real IR images. Statistical analyses included comparisons of nSI_vol between the cochlea and vestibule, side-to-side differences in EH-negative ears, paired comparisons of nSI_vol between larger- and smaller-%EL_vol sides, correlations between %EL_vol and nSI_vol, and receiver operating characteristic (ROC) curve analysis of nSI_vol for discriminating severe from mild/no EH. The presence of EH was defined based on the clinical diagnosis using Nakashima grading.

Results: The vestibular %EL_vol was significantly higher and the vestibular nSI_vol significantly lower than that in the cochlea (both P < 0.001). In EH-negative ears, no significant side-to-side difference in nSI_vol was observed. In both cochleae and vestibules, nSI_vol was significantly lower on the larger-%EL_vol side than on the smaller-%EL_vol side (cochlea: P = 0.002; vestibule: P = 0.007). Significant negative correlations between %EL_vol and nSI_vol were observed in both the cochlea (Spearman’s rank correlation coefficient [R_s] = –0.598, P < 0.001) and vestibule (R_s = –0.417, P < 0.001). The area under the ROC curve was 0.827 in the cochlea, and 0.698 in the vestibule.

Conclusion: The SI of the entire labyrinthine fluid measured on non–contrast-enhanced 3D–real IR imaging showed a significant negative correlation with the endolymphatic volume measured on contrast-enhanced HYDROPS-Mi2. These findings suggest that the SI of labyrinthine fluid, as measured on non–contrast-enhanced 3D–real IR images, may serve as an indirect indicator for estimating the degree of EH.

Purpose: To evaluate short T₂ components potentially reflecting calcification or other susceptibility-affected tissue components in atherosclerotic plaques, using multicomponent analysis with ultrashort TE (UTE) MRI.

Methods: A phantom experiment was conducted using a 4-echo UTE sequence, mimicking the sample as a small amount of calcification found intra-voxel. The phantom included 6 samples containing varying concentrations of hydroxyapatite (calcification) and mayonnaise (lipid–water emulsion). Data acquired from the UTE sequence were compared with those obtained using a conventional multi-echo gradient-echo (mGRE) method.

Results: Bi-exponential analysis of UTE data successfully separated short- and long-T₂* components, with ranges of 0.44–4.81 ms and 4.29–24.37 ms, respectively. Short T₂* values derived from UTE showed minor changes with increasing hydroxyapatite concentration. Using bi-exponential analysis of mGRE data, short and long T₂* values ranged from 0.17–0.77 ms and 6.16–39.20 ms, respectively. For mono-exponential fitting of mGRE data, T₂* values ranged from 4.84–38.32 ms. In all datasets, 1/T₂* increased with hydroxyapatite concentration. The signal fraction of short T₂* components in the UTE dataset decreased as hydroxyapatite concentration increased. A clinical scan of 1 patient with an atherosclerotic plaque yielded mean short and long T₂* values of 0.12 ± 0.35 ms and 33.22 ± 17.25 ms, respectively.

Conclusion: T₂* analysis using UTE data enabled the separation of mixed calcification and mayonnaise (lipid–water emulsion) within a sample into 2 components and detected short T₂* components that may reflect calcification-related susceptibility effects, without directly indicating calcification. Multicomponent T₂* analysis with UTE-MRI is a promising technique for evaluating calcification and other short T₂* components in atherosclerotic plaques.

This study presents a novel data augmentation approach to improve deep learning (DL)-based segmentation for 3D phase-contrast magnetic resonance angiography (PC-MRA) images affected by pulsation artifacts. Augmentation was achieved by simulating pulsation artifacts through the addition of periodic errors in k-space magnitude. The approach was evaluated on PC-MRA datasets from 16 volunteers, comparing DL segmentation with and without pulsation artifact augmentation to a level-set algorithm. Results demonstrate that DL methods significantly outperform the level-set approach and that pulsation artifact augmentation further improves segmentation accuracy, especially for images with lower velocity encoding. Quantitative analysis using Dice-Sørensen coefficient, Intersection over Union, and Average Symmetric Surface Distance metrics confirms the effectiveness of the proposed method. This technique shows promise for enhancing vascular segmentation in various anatomical regions affected by pulsation artifacts, potentially improving clinical applications of PC-MRA.

A novel imaging technique, CT-like MRI, specifically Fast Field Echo Resembling a CT Using Restricted Echo-spacing (FRACTURE), has been developed to depict bones. The purpose of this study is to evaluate the feasibility of FRACTURE MRI in cranial and facial bone lesions. Our results suggest that FRACTURE MRI can be used in addition to conventional MRI to evaluate a variety of pathologies of the cranial and facial bones.

A recently proposed non-contrast MRI technique for evaluating endolymphatic hydrops employs inversion recovery without T2-preparation and the subtraction of 2 inversion time images. However, our high-resolution non-contrast positive endolymph images (PEI) reveal inconsistencies in delineating the endolymphatic space, challenging this method’s reliability. Comprehensive analysis is required to address the interplay among signal intensity, T1 relaxation times, and inversion efficiency within endolymphatic and perilymphatic spaces to establish its diagnostic accuracy.

Purpose: This study aimed to quantitatively evaluate whether non-echoplanar diffusion-weighted MRI (non-EP DWI) lesion size and detectability can predict mastoid extension and complications such as labyrinthine fistula and dural exposure in middle ear cholesteatoma.

Methods: This retrospective study included 120 lesions with surgically confirmed middle ear cholesteatoma. Non-EP DWI was performed within 6 months preoperatively and evaluated for lesion detectability and size measurements, including maximum axial diameter, maximum axial area, and volume. Surgical findings were used to assess mastoid extension, labyrinthine fistula, and dural exposure.

Results: Of the 120 lesions, 30 were undetectable and 90 were detectable on non-EP DWI. Undetectable lesions had significantly less mastoid extension or labyrinthine fistula compared to detectable lesions (P < 0.001 − P = 0.006). The undetectable finding on non-EP DWI for identifying mastoid extension-negative lesions showed a sensitivity of 0.59, specificity of 0.95, and for labyrinthine fistula-negative lesions showed a sensitivity of 0.29, specificity of 1.00. Among the 90 detectable lesions, all size parameters (maximum axial diameter, maximum axial area, and volume) were significantly larger in cases with positive mastoid extension and positive labyrinthine fistula compared to negative cases (P < 0.001 − P = 0.005). For dural exposure, the maximum axial diameter and maximum axial area were significantly larger in positive cases (P = 0.002), but volume did not differ significantly. Optimal diagnostic cut-off values were determined for mastoid extension (8.9 mm diameter and 56 mm² area, both with sensitivity 0.89 and specificity 0.97), labyrinthine fistula (82 mm² area, sensitivity 0.47, specificity 1.00), and dural exposure (14.3 mm diameter, sensitivity 0.59, specificity 0.87; 112 mm² area, sensitivity 0.68, specificity 0.73).

Conclusion: Non-EP DWI lesion size and detectability can predict important operative findings in middle ear cholesteatoma. Undetectable lesions on non-EP DWI indicate a lack of mastoid extension or labyrinthine fistula, while larger detectable lesions correlate with increased risks of extension and complications.

Purpose: To investigate whether significant differences exist in labyrinthine lymph fluid signal intensities on non-contrast-enhanced 3D real inversion recovery (3D-real IR) images between patients with and without significant endolymphatic hydrops (EH), potentially enabling the non-contrast detection of EH.

Methods: Thirty-nine patients suspected of having EH underwent 3D-real IR MRI before and 4 hours after intravenous administration of a single dose of gadobutrol. Signal intensities of the cerebrospinal fluid (CSF), perilymph, and endolymph were manually measured on pre-contrast images using ROIs. Patients were categorized into 2 groups based on post-contrast imaging: those with significant EH and those without. Normalized signal intensities (nSIs) of the endolymph were calculated and compared between the groups using the Mann–Whitney U test.

Results: The nSIs of the vestibular endolymph on non-contrast 3D-real IR images were significantly lower in the group with significant EH compared to the group without EH (P  < 0.05), suggesting T1 prolongation in the vestibular endolymph of patients with significant EH. However, considerable overlap was observed in the nSIs between the 2 groups, and significant EH did not always result in T1 prolongation. No significant differences were found in the nSIs of the perilymph or CSF between the groups.

Conclusion: The study suggests that T1 prolongation occurs in the vestibular endolymph in cases of significant EH. This finding indicates the potential for developing non-contrast MRI methods to detect EH and underscores the importance of understanding the mechanisms behind T1 changes in the endolymph. Further research with larger patient cohorts and inclusion of healthy control subjects is necessary to validate these results and to elucidate the pathophysiology of EH in Ménière’s disease.

Purpose: We aimed to evaluate the quality of various 3D T₁-weighted images (T₁WIs) of the stent lumen using a carotid stent phantom and determine the suitable T₁WI sequence for visualization of the stent lumen after carotid artery stenting.

Methods: The carotid stent phantom consisted of polypropylene tubes that mimicked common carotid arteries with and without stenting. On 1.5T and 3.0T MRI scanners, transverse T₁WIs of the carotid stent phantom were obtained using 3D turbo spin-echo (TSE), 3D fast field-echo (3D-FFE), and 3D turbo field echo volumetric interpolated breath-hold examination (VIBE) under clinical conditions. The signal intensity ratio (SIR) was determined using the mean signal intensity of the stent lumen (SI_stent) divided by the lumen without a stent in each T₁WI. The SNR of the stent lumen (SNR_stent) was calculated from SI_stent divided by the standard deviation of the uniform region near the stent lumen.

Results: The 3D-FFE and VIBE had higher SNR_stent than other T₁WIs and clearly visualized the stent lumen. The 3D-TSE had the lowest SIR and SNR_stent, preventing stent lumen visualization.

Conclusion: T₁WIs obtained using 3D-FFE and VIBE allows stent lumen visualization.

Purpose: The 8th edition of the American Joint Committee on Cancer staging system included the depth of invasion (DOI) for the T classification of oral cancer. However, no standardized method has been established to clinically measure the DOI. This study aimed to investigate the accuracy of MRI-based DOI for oral tongue squamous cell carcinoma (OTSCC) in each MRI sequence.

Methods: We enrolled 49 patients with histologically proven OTSCC, treated surgically between April 2017 and February 2021. We divided the DOI into three groups using 5 and 10 mm, the thresholds for determining the T stage, and retrospectively evaluated the agreement between MRI-based DOI and pathological DOI (pDOI) for each MRI sequence, axial T1-weighted imaging (T1WI), T2-weighted imaging with fat suppression (FS-T2WI), contrast-enhanced T1WI with fat suppression (CE-T1WI), diffusion-weighted imaging (DWI), and apparent diffusion coefficient (ADC) maps. We also divided the DOI into two groups using 3 mm, the threshold for considering elective neck dissection, and evaluated the overestimation rate of MRI-based DOI in lesions with pDOI ≤ 3 mm.

Results: With 5-mm and 10-mm divisions, the accuracy of the DOI assessment was highest on DWI (0.82, weighted kappa = 0.85). With a 3-mm division, the accuracy was also highest on DWI (0.87, kappa = 0.73). The overestimation rate of the MRI-based DOI in lesions with pDOI ≤ 3 mm was lowest on DWI (27.8%).

Conclusion: DOI on DWI exhibits a comparatively higher rate of concordance with pDOI. DWI may be more useful than other MRI sequences in evaluating the DOI of OTSCC.

Purpose: The endolymph of the inner ear, vital for balance and hearing, has long been considered impermeable to intravenously administered gadolinium-based contrast agents (GBCAs) due to the tight blood-endolymph barrier. However, anecdotal observations suggested potential GBCA entry in delayed heavily T2-weighted 3D-real inversion recovery (IR) MRI scans. This study systematically investigated GBCA distribution in the endolymph using this 3D-real IR sequence.

Methods: Forty-one patients suspected of endolymphatic hydrops (EHs) underwent pre-contrast, 4-h, and 24-h post-contrast 3D-real IR imaging. Signal intensity in cerebrospinal fluid (CSF), perilymph, and endolymph was measured and analyzed for temporal dynamics of GBCA uptake, correlations between compartments, and the influence of age and presence of EH.

Results: Endolymph showed a delayed peak GBCA uptake at 24h, contrasting with peaks in perilymph and CSF at 4h. Weak to moderate positive correlations between endolymph and CSF contrast effect were observed at both 4 (r = 0.483) and 24h (r = 0.585), suggesting possible inter-compartmental interactions. Neither the presence of EH nor age significantly influenced endolymph enhancement. However, both perilymph and CSF contrast effects significantly correlated with age at both time points.

Conclusion: This study provides the first in vivo systematic confirmation of GBCA entering the endolymph following intravenous administration. Notably, endolymph uptake peaked at 24h, significantly later than perilymph and CSF. The lack of a link between endolymph contrast and both perilymph and age suggests distinct uptake mechanisms. These findings shed light on inner ear fluid dynamics and their potential implications in Ménière’s disease and other inner ear disorders.

Purpose: Recently, the utility of non-contrast MR endolymphatic hydrops imaging was reported, but the pitfall was indicated based on T2 preparation pulse sensitiveness to local static magnetic field (B0) inhomogeneity. The purpose of this study is to clarify the effects of surrounding magnetic environment of temporal bone to lymphatic fluid signal intensity on the T2 preparation and fluid attenuated inversion recovery pulse combination (T2prep 3D-FLAIR) technique in human inner ear study.

Methods: We prepared a custom-made phantom comprising a chicken leg bone submersed in saline. To evaluate signal characteristics of saline close to bone, multiple TE gradient echoes, T2 relaxation time measurement, and T2prep 3D-FLAIR image were acquired. In the vicinity of the vestibule of a healthy volunteer, similar examinations were executed. Additionally, to investigate the influence of the magnetic environment from B0, the evaluation was performed in five head position settings relative to B0.

Results: In both the phantom case and volunteer case, together with T2 star signal intensity attenuation, T2 relaxation time shortening was observed on fluid around bone. Specifically, at the outer edge in the vestibule and cochlea of the volunteer, T2 relaxation time was shorter than that of center of vestibule and that of cochlea. In the T2prep 3D-FLAIR image, higher signal intensity was observed at the same location on the outer edge of them. These results showed that bone affects surrounding fluid magnetic environment. Also, for B0 influence, despite a large area variation ratio, there is no statistically significant difference correlated to orientation within B0.

Conclusion: The surrounding magnetic environment of the temporal bone affects lymphatic fluid signals of the peripheral part of the human inner ear on T2prep 3D-FLAIR technique.

In this study, we present images acquired by a fast-imaging method for the evaluation of endolymphatic hydrops after intravenous administration of a single dose of gadolinium-based contrast agent. We utilized the hybrid of reversed image of MR cisternography and a positive perilymph signal by heavily T2- weighted 3D-fluid attenuated inversion recovery-multiplied by T2 (HYDROPS2-Mi2) method combined with deep learning reconstruction denoising. The scan time for the fast protocol was approximately 5 mins, which is far shorter than previously reported scan times. The fast acquisition provides similar image quality and less motion artifacts compared to the longer method.

Purpose: To evaluate the relationship between the size of the venous structures related to the inner ear and the degree of endolymphatic hydrops (EH).

Methods: Thirty-four patients with a suspicion of EH underwent whole brain MR imaging including the inner ear. Images were obtained pre- and post-administration, and at 4 and 24 hours after the intravenous administration of a gadolinium-based contrast agent (IV-GBCA). The cross-sectional areas (CSA) of the internal jugular vein (IJV), superior petrosal sinus (SPS), and inferior petrosal sinus (IPS) were measured on the magnetization prepared rapid acquisition of gradient echo (MPRAGE) images obtained immediately after the IV-GBCA. The grade of EH was determined on the hybrid of reversed image of positive endolymph signal and native image of positive perilymph signal (HYDROPS) images obtained at 4 hours after IV-GBCA as no, mild, and significant EH according to the previously proposed grading system for the cochlea and vestibule, respectively. The ipsilateral CSA was compared between groups with each level of EH grade. P < 0.05 was considered statistically significant.

Results: There were no statistically significant differences between EH grades for the CSA of the IJV or that of the IPS in either the cochlea or the vestibule. The CSA of the SPS in the groups with significant EH was significantly smaller than that in the group with no EH, for both the cochlea (P < 0.01) and the vestibule (P < 0.05). In an ROC analysis to predict significant EH, the cut-off CSA value in the SPS was 3.905 mm² for the cochlea (AUC: 0.8762, 95% confidence interval [CI]: 0.7952‒0.9572) and 3.805 mm² for the vestibule (AUC: 0.7727, 95% CI: 0.6539‒0.8916).

Conclusion: In the ears with significant EH in the cochlea or vestibule, the CSA of the ipsilateral SPS was smaller than in the ears without EH.

Purpose: Peripheral retinal leakage (PRL) of contrast medium from the ora serrata (i.e., the peripheral part of the retina) was recently reported in normal eyes using ultra-widefield fluorescein angiography. We occasionally see PRL of gadolinium-based contrast agents (GBCAs) in the vitreous from the temporal and inferior sides of the ora serrata on MR images of subjects without ophthalmic disease. In this study, we retrospectively evaluated these MR images to determine if PRL was associated with aging. We also evaluated whether the initial leakage appeared in the temporal and inferior sides, and whether there was uniform distribution within the vitreous after 24 hours.

Methods: In 127 subjects (9 volunteers, 85 patients with sudden deafness, and 33 patients with a suspicion of endolymphatic hydrops), pre- and post-contrast-enhanced heavily T2-weighted 3D-fluid attenuated inversion recovery (FLAIR) images were obtained. The presence or absence of PRL was subjectively evaluated. For patients with a suspicion of endolymphatic hydrops, 3D-real inversion recovery (IR) images were also obtained at pre-, 10 mins, 4 hours, and 24 hours after intravenous administration (IV) of GBCA. Four circular ROIs were placed in the vitreous humor and the signal intensity was measured.

Results: In the cases with PRL (n = 88) and without PRL (n = 47), the median age was 59 and 47 years, respectively (P = 0.001). At 4 hours after IV-GBCA, the mean signal increase in the inferior temporal ROI was greater than all the other ROIs. At 24 hours after IV-GBCA, no significant difference in signal intensity was observed for the four ROIs.

Conclusion: PRL of GBCA is age-dependent and occurs mainly from the inferior temporal side of the ora serrata. The contrast effect was uniformly distributed at 24 hours after IV-GBCA. Future observations in a variety of diseases will determine the clinical significance of these findings.

Purpose: To evaluate whether readout-segmented echo-planar imaging (RS-EPI) diffusion-weighted imaging (DWI) can reduce image distortion and improve the lesion identification in parathyroid adenomas (PTAs) compared to single-shot EPI (SS-EPI) DWI, and to determine whether PTAs can be differentiated from other soft tissue structures of the head and neck region by using the apparent diffusion coefficient (ADC) value.

Methods: We retrospectively analyzed the preoperative MR images including DWI of 24 patients with surgically confirmed PTA. RS-EPI and SS-EPI DWI were evaluated by two independent readers for the identification of the lesions and distortion. The ADC values of the PTAs were compared with those of thyroid glands and cervical lymph nodes.

Results: RS-EPI provided significantly less distortion compared to SS-EPI. RS-EPI tended to have better lesion identification compared with SS-EPI without a statistically significant difference. On SS-EPI, the PTAs had significantly higher ADC values compared with the cervical lymph nodes. On RS-EPI, the PTAs had significantly higher ADC values compared with the thyroid glands and cervical lymph nodes.

Conclusion: RS-EPI reduces the DWI distortion in PTAs. The ADC value obtained using RS-EPI enables the differentiation of PTAs from nearby structures, such as thyroid glands and cervical lymph nodes.