Key points
- A double-dose injection (0.4ml/kg) has started being applied in clinic
nowadays. The optimal image contrast was however, not observed after 4
hours post a double-dose injection. Hence, it is crucial to
investigate the optimal scan time at double dose administration.
- We found that 3D-FLAIR images with double-dose injection of gadolinium
contrast acquired at 6 hours post-injection showed the strongest image
contrast in the cochlea. The significantly higher CNR values were
shown at 6 hours than those acquire at other time points. In addition,
the optimal angles ranging from 6.20to 13.6 degrees were obtained.
- Therefore, the optimal scan time was found at 6 hours after injecting
contrast agent at double-dose. Together with the best scan angle
obtained, the EH can be accurately assessed on 3D-FLAIR images.
Introduction
Ménière’s disease(MD)is characterized by three clinical symptoms of
fluctuating low-frequency sensorineural hearing loss, tinnitus and/or
aural fullness, and vertigo attacks in about 0.2–0.5 % of the general
population (1,2).The diagnosis of MD is based upon the typical clinical
syndrome complemented with a battery of audiological, vestibular, and
electrophysiological tests and the demonstration of endolymphatic
hydrops (EH)(3,4). However, the latter onewas lack of a gold standard
diagnostic test, and could only be obtained by histological post-mortem
examination previously.
Magnetic resonance imaging(MRI) has been reported for the potential in
the clinical diagnosis of MD.After Zou et al. was the first study
reportinga separate visualization of endolymph and perilymph regions in
living humans using MRI (5), Nakashima et al (6)showed the feasibility
of gadolinium enhanced MRI in the visualization of EH in living MD
patients. With intravenous injection of gadolinium-based contrast media
(GBCM), three-dimensional fluid-attenuated-inversion-recovery (3D-FLAIR)
imaging hasbeen reported to visualize EH (7-11). The optimal scan time
reported was 4hours after the administration of GBCM at a single-dose
(0.2ml/kg)(7).The concentration of GBCM in the perilymph after
single-dose intravenous injection however is too low to be detected by
convention 3D-FLAIR in patients without impaired permeability of the
blood labyrinthine barrier (12)and is challenging to achieve consistent
gadolinium enhancement in the upper part of the cochlea
(1,13), although it has been used
widely in a number of clinical applications.Therefore, a higher dose of
contrast agent is requested in labyrinthineimaging. Under FDA approved
maximal triple dose of gadolinium (i.e. 0.3 mmol/kg) for human imaging,
a
double-dose injection (0.4ml/kg), aiming to obtain higher signal
intensity (14), has started being applied in clinic nowadays.The optimal
image contrast was however, not observed after 4 hours posta double-dose
injection. Hence, it is crucial to investigate the optimal scan time at
double dose administration.
On the other hand, the 3D image volume for bilateral inner ear is
essential to be adjusted in three directions. While a proper adjustment
in axial and coronal directions can ensure symmetrical display for
bilateral inner ears, a suitable scan angle applied in sagittal view
plays an important role in labyrinthine imaging.With this, the relative
maximum areas of the saccule, utricle and lateral semicircular canal can
thus be provided at the same level to accurately estimate the EHand
judge whether EH herniation occurs in the lateral semicircular canal.
However, this optimal scan angle with the anterior skull base remains
unknow so far.
Therefore, this study wasto explore the optimal imaging parameters of
3D-FLAIR, including the optimal scan time at double dose administration
and scan angle, in labyrinthine imaging for patients with vertigo and
sensorineural hearing loss.
Materials and methods