Increased signal intensity of low-concentration gadolinium contrast agent by longer repetition time in heavily T2-weighted-3D-FLAIR.

PURPOSE: To apply for detecting low-concentration gadolinium contrast agent (Gd), such as those in the perilymph and cerebrospinal fluid (CSF) at 4 h after intravenous administrations (IV), we tried to clarify the degree of increased signal intensity (SI) of low-concentration Gd by longer repetition time (TR) in heavily T2-weighed 3D-FLAIR. MATERIALS AND METHODS: A phantom was designed using Gd diluted with saline at 0.250-0.008 mM and obtained images by varying the TR from 9000 to 16,000. We measured the SI of five slices for each concentration and compared the mean SI (SImean) values. Normalized SI (SInorm) values, defined as the SImean value of each TR divided by the SImean value of 9000-ms TR for each concentration were compared. RESULTS: Longer TR increased the SImean values in all solutions. In the 0.250 mM solution, the SImean value of 16,000-ms TR was 1.07-times greater than that of 9000-ms TR. In contrast, the SImean value of 16,000-ms TR was 1.67-times greater than that of 9000-ms TR in 0.008 mM solution. CONCLUSION: SI increased with longer TR and lower Gd concentration. Thus, longer TR was useful in detecting low-concentration Gd, such as those in the perilymph and CSF at 4 h after IV.

MR imaging of Ménière's disease after combined intratympanic and intravenous injection of gadolinium using HYDROPS2.

Endolymphatic hydrops (EH) in Ménière's disease is currently evaluated by 3-dimensional (3D)-real inversion recovery (IR) sequence after intratympanic (IT) administration of gadolinium (Gd) or by heavily T2-weighted (hT2W)-3D-fluid-attenuated IR (FLAIR) sequence after intravenous (IV) injection of Gd. Unilateral IT injection is usually performed. We employed a method in which we simultaneously administered contrast into one ear intravenously (IV side) and into the other ear both intravenously and intratympanically (IT + IV side) to evaluate EH in 10 patients with Ménière's disease. We then compared a HYDROPS2 image obtained by subtracting magnetic resonance cisternography from hT2W-3D-FLAIR with an image obtained by 3D-real IR and found that we could evaluate EH in all ears on the HYDROPS2 image but only in the IT + IV side on the 3D-real IR image.

Visualization of white matter tracts using a non-diffusion weighted magnetic resonance imaging method: does intravenous gadolinium injection four hours prior to the examination affect the visualization of white matter tracts?

OBJECTIVES: Visualization of white matter (WM)-tracts such as the corticospinal tract (CST), medial lemniscus (ML), and superior cerebellar peduncle (SCP) using delayed enhanced (DE)-heavily T2-weighted three-dimensional fluid-attenuated inversion-recovery (hT2w-3D-FLAIR) imaging has recently been reported. In that report, all patients were clinically suspected of having Ménière's disease, because DE-hT2w-3D-FLAIR imaging of the inner ear has been reported to separately visualize perilymph and endolymph fluid and can identify the presence of endolymphatic hydrops. Therefore, the previous report could not rule out the possible effect of delayed enhancement. From this perspective, the purpose of this study was to elucidate if the use of gadolinium affects the visualization of WM-tracts on hT2w-3D-FLAIR. MATERIALS AND METHODS: The records of nine patients with suspected Ménière's disease who underwent plain (P) and DE-hT2w-3D-FLAIR by 3-Tesla were retrospectively analyzed. The regions of interest were set on the CST, ML, and SCP, and on contiguous brain parenchyma: The thalamus (Th), pontine parenchyma (PP), and cerebellar parenchyma (CP), respectively. The signal intensity ratio between each WM-tract and the relevant contiguous brain parenchyma was calculated for both P- and DE-hT2w-3D-FLAIR images, and statistically compared using paired t-tests. RESULTS: The CST/Th signal intensity ratio was 3.75±0.67 on P-hT2w-3D-FLAIR and 3.62±0.50 on DE-hT2w-3D-FLAIR (p = 0.24). The ML/PP signal intensity ratio was 2.19±0.59 on P-hT2w-3D-FLAIR and 2.08±0.53 on DE-hT2w-3D-FLAIR (p = 0.25). The SCP/CP signal intensity ratio was 4.08±0.91 on P-hT2w-3D-FLAIR and 4.04±0.96 on DE-hT2w-3D-FLAIR (p = 0.43). There were no significant differences in the signal intensity ratios between P- and DE-hT2w-3D-FLAIR images. CONCLUSIONS: The use of gadolinium is not necessary for visualization of WM-tracts using hT2w-3D-FLAIR, and P-hT2w-3D-FLAIR without gadolinium may have future clinical applications as an imaging procedure.

Visualization of brain white matter tracts using heavily t2-weighted three-dimensional fluid-attenuated inversion-recovery magnetic resonance imaging.

The purpose of this study was to elucidate which white matter (WM)-tracts are visualized on heavily T2-weighted three-dimensional fluid-attenuated inversion-recovery (hT2w-3D-FLAIR) images. Records of seven patients who underwent hT2w-3D-FLAIR and diffusion tensor imaging (DTI) of the head at 3 Tesla were analyzed. Two neuroradiologists determined WM-tracts visualized on hT2w-3D-FLAIR and identified anatomical points through which they ran. A third neuroradiologist determined the WM-tracts running through those points on DTI. Correspondence between hT2w-3D-FLAIR and DTI WM-tracts was used to confirm technique validity. As a result, the corticospinal tract (CST), medial lemniscus (ML), and superior cerebellar peduncle (SCP) were visualized as high intensity on hT2w-3D-FLAIR and ran through the following points: CST, 20 mm lateral from the lateral margin of the third ventricle at the thalamic level; ML, 6 mm anterior to the anterior margin of the fourth ventricle at the trigeminal nerve level; and SCP, just lateral to the fourth ventricle at the trigeminal nerve level. The third neuroradiologist determined that the WM-tracts ran through those points on DTI in all patients. Consequently, WM-tracts determined on hT2w-3D-FLAIR and DTI completely corresponded. In conclusion, the CST, ML, and SCP were visualized as high intensity on hT2w-3D-FLAIR. This technique is a potentially supplemental DTI neurographic modality.

Semi-quantification of endolymphatic size on MR imaging after intravenous injection of single-dose gadodiamide: comparison between two types of processing strategies.

PURPOSE: Many inner ear disorders, including Ménière's disease, are believed to be based on endolymphatic hydrops. We evaluated a newly proposed method for semi-quantification of endolymphatic size in patients with suspected endolymphatic hydrops that uses 2 kinds of processed magnetic resonance (MR) images. METHODS: Twenty-four consecutive patients underwent heavily T2-weighted (hT2W) MR cisternography (MRC), hT2W 3-dimensional (3D) fluid-attenuated inversion recovery (FLAIR) with inversion time of 2250 ms (positive perilymph image, PPI), and hT2W-3D-IR with inversion time of 2050 ms (positive endolymph image, PEI) 4 hours after intravenous administration of single-dose gadolinium-based contrast material (IV-SD-GBCM). Two images were generated using 2 new methods to process PPI, PEI, and MRC. Three radiologists contoured the cochlea and vestibule on MRC, copied regions of interest (ROIs) onto the 2 kinds of generated images, and semi-quantitatively measured the size of the endolymph for the cochlea and vestibule by setting a threshold pixel value. RESULTS: Each observer noted a strong linear correlation between endolymphatic size of both the cochlea and vestibule of the 2 kinds of generated images. The Pearson correlation coefficients (r) were 0.783, 0.734, and 0.800 in the cochlea and 0.924, 0.930, and 0.933 in the vestibule (P<0.001, for all). In both the cochlea and vestibule, repeated-measures analysis of variance showed no statistically significant difference between observers. CONCLUSION: Use of the 2 kinds of generated images generated from MR images obtained 4 hours after IV-SD-GBCM might enable semi-quantification of endolymphatic size with little observer dependency.

Estimation of perilymph enhancement after intratympanic administration of Gd-DTPA by fast T1-mapping with a dual flip angle 3D spoiled gradient echo sequence.

Eleven patients with suspected Ménière's disease received intratympanic (IT) administration of gadolinium (gadopentetate dimeglumine; Gd) prior to acquisition of 3-dimensional (3D) fluid-attenuated inversion recovery (FLAIR), 3D real inversion recovery (IR), and fast T1 mapping by dual flip angle 3D gradient echo (FT1-map) imaging sequences to evaluate the degree of perilymph enhancement. Though 3-dimensional FLAIR could detect lower concentrations of gadolinium than 3D real IR, in 2 patients, poor enhancement still prevented visualization of the endolymphatic space using 3D FLAIR. We could predict poor contrast enhancement in these 2 patients using the FT1-map technique.

Three-dimensional visualization of endolymphatic hydrops after intravenous administration of single-dose gadodiamide.

Endolymphatic hydrops can be visualized with high contrast-to-noise ratio even after intravenous injection of single-dose gadolinium-based contrast material (IV-SD-GBCM) using HYDROPS-Mi2 images. We applied 3-dimensional rendering software to process HYDROPS-Mi2 images of 15 ears with and without suspected Ménière's disease and separately visualized the volumes of endo- and perilymph in patients with Ménière's disease even after IV-SD-GBCM. Such dimensional visualization will aid understanding of the pathophysiology of Ménière's disease.

Imaging of Ménière's disease after intravenous administration of single-dose gadodiamide: utility of multiplication of MR cisternography and HYDROPS image.

A HYDROPS (HYbriD of Reversed image Of Positive endolymph signal and native image of positive perilymph Signal) image, created by subtracting a positive endolymph image from a positive perilymph image after intravenous injection of single-dose gadodiamide, has been reported to facilitate recognition of endolymphatic hydrops. To further increase the contrast-to-noise ratio (CNR) of HYDROPS images, we multiplied a T2-weighted MR cisternographic image onto the HYDROPS image. Ten patients with suspected Ménière's disease were included. The average CNR of generated images increased to more than 200 times that of HYDROP images.

Imaging of Ménière's disease by subtraction of MR cisternography from positive perilymph image.

To visualize endolymph, perilymph, and bone separately in a single image after intravenous injection of single-dose gadodiamide, we generated a HYDROPS2 image (subtraction of MR cisternography from heavily T(2)-weighted 3-dimensional fluid-attenuated inversion recovery image) in 12 patients with suspected Ménière's disease. The contrast-to-noise ratio of endo- and perilymph did not differ significantly between the HYDROPS2 and previously reported HYDROPS (hybrid of reversed image of positive endolymph signal and native image of positive perilymph Signal) images, and scan time was 40% shorter for the HYDROPS2 than HYDROPS.

Imaging of Ménière's disease after intravenous administration of single-dose gadodiamide: utility of subtraction images with different inversion time.

For the separate visualization of endolymph, perilymph, and bone on a single image after intravenous injection of single-dose gadodiamide, we fused gray-scale inverted positive endolymph (PEI) with native positive perilymph (PPI) images, that is, we subtracted PEI from PPI. Subtraction significantly improved the contrast noise ratio between endolymph and perilymph and the subjective visibility score for endolymphatic space. The 24 patients with the suspect of Ménière's disease were included.

Imaging of endolymphatic and perilymphatic fluid after intravenous administration of single-dose gadodiamide.

To visualize endolymph as bright signal after intravenous injection of single-dose gadodiamide, we shortened the inversion time of heavily T(2)-weighted 3-dimensional (3D) fluid-attenuated inversion recovery (FLAIR) to 2050 ms. In 14 patients with suspected Ménière's disease, we observed high signal of vestibular endolymph in all ears, including 6 ears without vestibular endolymphatic hydrops. We observed high signal of cochlear endolymph in 17 ears with cochlear endolymphatic hydrops but not 11 ears without cochlear endolymphatic hydrops.

Visualization of endolymphatic hydrops in Ménière's disease after single-dose intravenous gadolinium-based contrast medium: timing of optimal enhancement.

PURPOSE: Visualization of endolymphatic hydrops (EH) in patients with Ménière's disease (MD) is now possible by heavily T(2)-weighted 3-dimensional fluid-attenuated inversion recovery (hT(2)W-3D-FLAIR) obtained 4 hours after intravenous (IV) administration of single dose gadolinium-based contrast medium (GBCM). Although maximum enhancement has been reported 4 hours after contrast administration in healthy volunteers, the timing of optimal enhancement in patients with MD is not reported. We investigated if that optimal timing is earlier or later than 4 hours. MATERIALS AND METHODS: We evaluated 10 consecutive patients with suspected MD whom we randomly divided into 2 groups. We obtained hT(2)W-3D-FLAIR before GBCM administration and 10 min, 3.5 hours, and 4 hours after GBCM administration in Group A and before and 10 min, 4 hours, and 4.5 hours after GBCM administration in Group B. We compared signal intensity ratio (SIR) values of the perilymph and pons between 3.5 and 4 hours in Group A and between 4 and 4.5 hours in Group B and evaluated grades of EH at 3.5 and 4 hours in Group A and at 4 and 4.5 hours in Group B. RESULTS: SIR values did not differ significantly between 3.5 and 4 hours in Group A and between 4 and 4.5 hours in Group B. However, SIR values at 4 hours were significantly higher in Group A than Group B. Grades of EH agreed between 3.5 and 4 hours in Group A and between 4 and 4.5 hours in Group B. CONCLUSION: The optimal timing of contrast enhancement in patients with suspected MD remains unclear, but evaluation of EH may be possible from 3.5 to 4.5 hours after contrast administration.

Visualization of endolymphatic hydrops in Ménière's disease with single-dose intravenous gadolinium-based contrast media using heavily T(2)-weighted 3D-FLAIR.

Heavily T(2)-weighted 3-dimensional fluid-attenuated inversion recovery (hT(2)W-3D-FLAIR) technique has been reported to be more sensitive than conventional 3D-FLAIR in detecting low concentrations of gadolinium-based contrast media (GBCM) in fluid. We applied hT(2)W-3D-FLAIR to visualize endolymphatic hydrops of Ménière's disease in 3 patients 4 hours after single-dose intravenous injection of GBCM and successfully visualized endolymphatic hydrops in either the cochlea or vestibule in all patients. This technique can be implemented in a clinical setting.