Postcontrast Fluid-attenuated Inversion Recovery Research Articles

Imaging meningiomas: Is there a need for post-contrast FLAIR?

The aim of this study was to compare post-contrast fluid-attenuated inversion recovery (FLAIR) imaging with post-contrast T1-weighted images (T1WI) in depicting meningiomas. Twenty-nine patients with 46 meningiomas were included in this study. FLAIR and T1WI were obtained before and after intravenous administration of gadopentetate dimeglumine. The contrast enhancement degree, contrast enhancement pattern, lesion conspicuity, and the detection of the dural sign were compared between post-contrast FLAIR images and post-contrast T1WI. The enhencement degree on FLAIR was equal or less than T1WI for all meningiomas. Among 46 meningiomas 38 (83%) enhanced homogeneously and eight (17%) inhomogeneously on T1WI. On contrast-enhanced FLAIR images, of the total 46 meningiomas 22 (48%) enhanced homogeneously, eight (17%) inhomogeneously, whereas 14 (30%) meningiomas showed a peripheral rim enhancement not observed on T1WI. Two (5%) meningiomas showed no contrast enhancement on post-contrast FLAIR images. Among the 14 meningiomas showing rim enhancement using FLAIR imaging, 12 (85%) were measured to be 2 cm or more in diameter. A dural tail sign was found in 16 (35%) and 23 (50%) meningiomas on post-contrast T1WI and FLAIR images, respectively. In contrast to other extra-axial diseases, post-contrast FLAIR sequence was not found to be a valuable adjunct to contrast-enhanced T1WI in the depiction of meningiomas.

Relationship between contrast enhancement on fluid‐attenuated inversion recovery MR sequences and signal intensity on T2‐weighted MR images: Visual evaluation of brain tumors

To investigate the relationship between the degree of contrast enhancement in fluid-attenuated inversion recovery (FLAIR) sequences and tumor signal intensity on T2-weighted images. A total of 96 patients suspected of having brain tumors were examined by MR imaging, and whenever a brain tumor with an enhancing part larger than the slice thickness was demonstrated on postcontrast T1-weighted images, postcontrast FLAIR images were additionally acquired. The tumor signal intensity on the T2-weighted images was visually classified as follows: equal or lower compared with normal cerebral cortex (group 1), higher than normal cortex (group 2), and as high as cerebrospinal fluid (CSF) (group 3). When a lesion contained several parts with different signal intensities on T2-weighted images, we assessed each part separately. In each group, we visually compared pre- and postcontrast FLAIR images and assessed whether tumor contrast enhancement was present. When contrast enhancement was present on FLAIR sequence, the degree of contrast enhancement in T1-weighted and FLAIR sequences was visually compared. Postcontrast T1-weighted images showed 46 enhancing lesions, including 48 parts, in 31 MR examinations. FLAIR images of the lesion-parts in group 1 (N=18) did not show significant contrast enhancement. In group 2 (N=12), all the parts were enhanced in FLAIR sequences, and three parts were enhanced more clearly in the FLAIR sequences than in the T1-weighted sequences. In group 3 (N=18), all the parts were enhanced equally or more clearly in the FLAIR sequences than in the T1-weighted sequences. The signal intensity in FLAIR sequences is largely influenced by both T1 and T2 relaxation time; there is a close relationship between the signal intensity of brain tumors on T2-weighted images and the degree of contrast enhancement on FLAIR sequences. When tumors have higher signal intensity than normal cortex on T2-weighted images, additional postcontrast FLAIR imaging may improve their depiction.