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Application of half-dose contrast-enhanced T2-fluid-attenuated inversion recovery (FLAIR) sequence in brain metastasis

Teng Jin¹, Zhenwei Yao¹, Jianxun Qu², and Yong Zhang³

¹Huashan Hospital, Fudan University, Shanghai, China, ²GE Healthcare, Shanghai, China, ³GE Healthcare,Shanghai,China, Shanghai, China

Synopsis

The treatment for brain metastasis are mainly depended on the number, size and location of lesions, to evaluate the number of brain metastatic lesions sensitively with contrast enhanced series is more important for patient treatment. The aim of this study was to assess the efficiency of half-dose contrast enhanced T2FLAIR used in the detection of intracranial metastases in comparison to full-dose enhanced T1-weighted imaging.

Background and objective

Background: Brain metastasis treatment mainly depends on the number, size, and location of lesions. It is important for treatment to sensitively evaluate the number of brain metastases using a contrast enhanced (CE) series.

Objective: To assess the detection rate and image quality of ½-dose CE T2-fluid-attenuated inversion recovery (FLAIR) in intracranial metastases, compared with CE-T1-weighted imaging (T1WI).

Materials and Methods

Materials and Methods：Thirty-three patients with known cancers and brain metastasis underwent pre- and post-contrast sequences including: i) ½-dose CE-T2-FLAIR, ii) ½-dose CE-T1WI, and iii) full-dose CE-3D-BRAVO sequence scan. The optimum scanning time for ½-dose CE-T2-FLAIR was analyzed, and we compared contrast ratio (CR) and the number of parenchymal metastases on three sequences above.

Results:

Results: One hundred and forty-one ½-dose CE-T2-FLAIR, 88 ½-dose CE-T1WI, and 123 full-dose CE-BRAVO sequence-enhanced lesions were classified as metastases. When metastases were ring-enhanced or solid-enhanced with a diameter of <5 mm, the number of metastases detected in ½-dose CE-T2-FLAIR was higher than that in ½-dose CE-T1WI and full-dose CE-BRAVO. However, if solid-enhanced metastases were ≥5 mm, the number of metastases detected in ½-dose CE-T2-FLAIR was less than that in ½-dose CE-T1WI or full-dose CE-BRAVO. In 77 metastatic lesions which both displayed in three sequences, the median CR was significantly higher using optimized ½-dose CE-T2-FLAIR (in phase 2, CR=71.6) than ½-dose CE-T1WI (CR=11.7, P<0.001) or full-dose CE-BRAVO sequence (CR=18.9, P<0.001).

Conclusion

Conclusion: Half dose CE-T2-FLAIR has distinct advantage in detecting brain metastases, especially ring-enhanced or small solid-enhanced lesions.

Acknowledgements

Bracco international B.V.

GE healthcare

References

Figures

Fig. 1. A 64-year-old male with lung adenocarcinoma (a) Plain T2-FLAIR demonstrated high signal intensity on the right parietal cortex (arrowhead). (b–d) Lesion on a ½-dose CE-T2-FLAIR immediate scan with a delay for 5 min and delay for 8 min showed ring-enhancement. The CR of the ring-wall presented with increasing tendency. The enhancement degree of the metastases delay in phase 2 (c) and phase 3 (d) was obviously higher than in phase 1 (b, arrowhead). (e) The ring-enhanced lesion in ½-dose CE-T1WI is obscure (arrowhead), and the CR of the ring-wall was obviously lower than in the ½-dose CE-T2-FLAIR in any phase. (f) The CR of the ring-wall in full-dose CE-BRAVO (arrowhead) was lower than in the ½-dose CE-T2-FLAIR delay in phase 2 and phase 3, but was higher than in ½-dose CE-T1WI.

Fig. 2. Images obtained from a 63-year-old male with lung adenocarcinoma demonstrated multiple small solid-enhanced (with diameter <5 mm) and ring-enhanced parenchymal metastases. (a) Many lesions were found on the plain T2-FLAIR sequence, and most lesions were located in the cortex and the subcortical white matter. The number and CR value are superior on the ½-dose CE-T2-FLAIR (b) compared with the ½-dose CE-T1WI (c) and full-dose CE-BRAVO (d) sequence (arrowheads).

Fig. 3. Images of a 48-year-old male with lung adenocarcinoma. (a) Plain T2-FLAIR image. (b) ½-dose CE-T2-FLAIR image. (c) ½-dose CE-T1WI image. (d) Full-dose CE-BRAVO image. Solid-enhanced metastases with shortest diameter of ≥5 mm in the right parietal cortex were clearly detected using the ½-dose CE-T1WI and full-dose CE-BRAVO (long arrowhead), but were misdiagnosed using ½-dose CE-T2-FLAIR (long arrowhead). Solid-enhanced metastases with shortest diameter of <5mm in the left prefrontal cortex (short arrowhead) were clearly detected using the ½-dose CE-T2FLAIR and not clearly displayed in full-dose CE-BRAVO (short arrowhead), but were misdiagnosed using ½-dose CE-T1WI sequence.

Proc. Intl. Soc. Mag. Reson. Med. 27 (2019)

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