Increased signal intensity with delayed post contrast 3D-FLAIR MRI sequence using constant flip angle and long repetition time for inner ear evaluation - 31/03/22
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Highlights |
• | After intravenous administration of gadolinium-based contrast agent, gadolinium passagethrough the blood-labyrinth barrier is weak leading to low concentration of gadolinium in the perilymphatic space. |
• | Elongation of the repetition time (TR) increases the signal intensity ratio (SIR) and contrast-to-noise ratio (CNR) while preserving diagnostic accuracy. |
• | The sensitivity of 3D-FLAIR sequences to low concentration gadolinium in the perilymphatic space is increased (+34.4%) by elongation of the TR. |
Abstract |
Purpose |
The purpose of this study was to compare the degree of perilymphatic enhancement between 4 hour post-contrast constant flip angle three-dimensional fluid attenuated inversion recovery (3D-FLAIR) images obtained with short repetition time (TR) and those obtained with long TR.
Materials and methods |
This single-center, prospective study included patients who underwent MRI of the inner ear with heavily T2-weighted sequence, 3D-FLAIR sequence with a “short” TR of 10,000 ms (s3D-FLAIR) and with a “long” TR of 16,000 ms (l3D-FLAIR). Signal intensity ratio (SIR) and contrast-to-noise ratio (CNR) obtained with s3D-FLAIR and l3D-FLAIR were quantitatively assessed using region of interest (ROI) method and compared. The morphology of the endolymphatic space on both sequences was also evaluated.
Results |
From March 2020 to July 2020, 20 consecutive patients were enrolled (9 women and 11 men; mean age, 52.1 ± 14.5 [SD] years; age range: 29–75 years). On l3D-FLAIR images, mean SIR (21.1 ± 8.8 [SD]; range: 7.6–46.1) was significantly greater than that on s3D-FLAIR images (15.7 ± 6.7 [SD]; range: 5.9–33.4) (P < 0.01). On l3D-FLAIR images, mean CNR (17 ± 8.5 [SD]; range: 2–40) was significantly greater than that on s3D-FLAIR images (12 ± 6.3 [SD]; range: 3.2–29.8) (P < 0.01). Kappa value for inter-rater agreement for endolymphatic hydrops, vestibular atelectasis and perilymphatic fistula were 0.93 (95% CI: 0.74–1), 1 (95% CI: 0.85–1) and 1 (95% CI: 0.85–1) respectively.
Conclusion |
This study demonstrates that the sensitivity of 3D-FLAIR sequences to low concentration gadolinium in the perilymphatic space is improved by elongation of the TR, with SIR and CNR increased by +34.4% and +41.3% respectively.
Il testo completo di questo articolo è disponibile in PDF.Keywords : 3D-FLAIR, Endolymphatic hydrops, Inner ear, Magnetic resonance imaging (MRI)
Abbreviations : 3D, CI, CNR, EH, FLAIR, l3D-FLAIR, MRI, ROI, s3D-FLAIR, SD, SI, SIR, SNR, TE, TR
Mappa
Vol 103 - N° 4
P. 225-229 - aprile 2022 Ritorno al numero
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