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"ASL-CE mismatch": An Imaging Finding for Diagnosis of Brain Tumor, Multicenter Research
Takashi Abe1, Maki Otomo1, Mihoko Kondo1, Yuta Arai1, Yoichi Otomi1, Yuki Matsumoto2, Yuki Kanazawa2, Kohei Nakajima3, Yoshifumi Mizobuchi3, Yasushi Takagi3, and Masafumi Harada2
1Radiology and Radiation Oncology, Tokushima University Hospital, Tokushima, Japan, 2Tokushima University, Tokushima, Japan, 3Neurosergery, Tokushima University Hospital, Tokushima, Japan

Synopsis

One hundred one cases with brain tumor were included (62: HGG, 10: LGG, 18: metastasis, 11: lymphoma), and divided into two groups by the presence or absence of ASL hyperintensity outside of CE area (ASL-CE mismatch). Only the cases with glioma or lymphoma (23 HGG, 7 LGG, 3 lymphoma) revealed ASL-CE mismatch, and the cases with metastasis didn't (p = 0.001). Similar results were obtained in a sub-analysis where data were divided by MRI vendor. This novel finding may reflect tumor invasion and/or vascular growth in the surrounding brain parenchyma, and is useful for identifying metastasis from the other tumors.

INTRODUCTION

The differential diagnosis of brain tumors is critical in determining optimal therapy and estimating prognosis. High grade glioma (HGG), brain metastasis and lymphoma are common types of brain malignancies in adults and can manifest similar findings on conventional MRI. ASL offers a non-invasive measurement of blood flow image, without any contrast media. We’ve reported the usefulness of ASL hyperintensity outside of CE area (ASL-CE mismatch) for brain tumor diagnosis in single center trial 1 2. At this time, we would validate its usefulness in multi-institutional research.

METHODS

One-hundred fifty-four cases who underwent MR examination (T1WI, T2WI, ASL and CE-T1WI) for suspected brain tumor were registered to this institutional review board approved study, and 101 cases were included for the analysis (62: HGG, 10: low grade glioma, LGG, 18: metastasis, 11: lymphoma). The cases were divided into two groups by the presence or absence of ASL hyperintensity outside of contrast enhanced area (ASL-CE mismatch). Tumor histology were compared between the two groups.

RESULT

Thirty-three cases showed ASL-CE mismatch (23: HGG, 7: LGG, 3: lymphoma). All cases with metastatic brain tumor didn’t show ASL-CE mismatch, and this finding was useful for differentiate metastasis from the other tumors (p = 0.001, Mann-Whitney U, SPSS v.24). Similar results were obtained in a sub-analysis where data were divided by MRI vendor.

DISCUSSION

Metastatic brain tumors tend to be confined to the contrast enhanced area, but gliomas and lymphomas, these are infiltrative tumors that are known to infiltrate outside the contrast enhanced area. The ASL-CE mismatch findings are thought to reflect the tumor invasion outside this contrast area and the accompanying vascular growth. It is also possible that the cytokine produced by the tumor may have induced vascular growth around the contrast zone. Pathological examination is necessary. Pathological examination is needed to confirm what ASL-CE mismatch means.

CONCLUSION

ASL-CE mismatch would be potentially useful for diagnosis of brain tumor.

Acknowledgements

This work was supported by the research grant from Bayer Yakuhin, Japan.We would like to express our deep appreciation to the participating institutions: Tokushima University, Hokkaido University, Hirosaki University, Tohoku University, Yamagata University, Yamanashi University, Jichi Medical University,Nippon Medical School Chiba Hokusoh Hospital, Kanazawa Medical University, Osaka medical College, Kagoshima University, Japan.

References

1. Abe T, Irahara S, Otomi Y, et al. Discrepancy between arterial spin labeling images and contrast-enhanced images of brain tumors. Proc Intl Soc Mag Reson Med 2015;23:2276 2. Abe T, Mizobuchi Y, Sako W, et al. Clinical Significance of Discrepancy between Arterial Spin Labeling Images and Contrast-enhanced Images in the Diagnosis of Brain Tumors. Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine 2015;14:313-319

Figures

Fig.1. Flow diagram summarizing the identification and inclusion of the cases.

Fig. 2. Summary of the result. Thirty-three cases showed ASL-CE mismatch (23: HGG, 7: LGG, 3: lymphoma). All cases with metastatic brain tumor didn’t show ASL-CE mismatch, and this finding was useful for differentiate metastasis from the other tumors (p = 0.001, Mann-Whitney U, SPSS v.24).

Fig. 3. Lymphoma that invades the brain stem and cerebellum. Contrast-enhanced T1WI (left), T2WI (center), and ASL image (right). In addition to a round strong contrast enhancement in their right cerebellum, punctate and linear contrast effects along the cerebellar pia matter are also seen. In ASL image, a strong high signal is seen outside the solid contrast zone (arrow).

Fig. 4. Metastatic brain tumor from primary lung adenocarcinoma. Contrast-enhanced T1WI (left), T2WI (center), and ASL image (right). A ring-like enhancement is observed in the left parietal occipital lobe (left), that indicating metastatic brain tumor. Hyperintensity spreads around the tumor on T2WI, which is thought to be a peritumoral edema (center). There is no hyperintensity on ASL image on and around the contrast enhanced tumor (right).

Proc. Intl. Soc. Mag. Reson. Med. 28 (2020)
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