Tomoyuki Noguchi
Blood flow is an important physiological variable that reflects biological activity, and tends to reflect functional aspects of a particular tissue. Arterial spin-labeling MR imaging (ASL-MRI) is an innovative imaging sequence capable of mapping blood flow distribution without the use of a contrast agent, that is, noninvasively. Considering that, in recent years, the application of contrast agents has been strictly regulated, ASL-MRI is highly desirable as an answer to clinical demands for the imaging of function-related activity without administration of extrinsic tracers.
In this article, we aimed to explore the pathologic background of the contrast provided by ASL-MRI, and applied it to brain tumors in a search for histopathologic indicators. A good correlation was found between relative tumor vessel density measured from specimens and relative signal intensity value on ASL-MRI, irrespective of histopathologic type. Moreover, ASL-MRI was capable of differentiating high-grade glioma from low-grade glioma, or hemangioblastoma from others. Based on this powerful evidence, ASL-MRI can facilitate the estimation of blood vessel density in brain tumors, differentiate malignant histopathologic types, or identify specific types of brain tumors.
I have been specializing in ASL-MRI for over a decade. Now I am energetically approaching clinical research, employing ASL-MRI in pediatric CNS disease, cerebrovascular disease, and symptomatic epilepsy in a Far East land—that is, in Tokyo, Japan. I truly hope that advances in the clinical application of ASL-MRI will help us better understand functional changes of the brain in diseases of the CNS.
References
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- Kimura H, Takeuchi H, Koshimoto Y, et al. Perfusion imaging of meningioma by using continuous arterial spin-labeling: comparison with dynamic susceptibility-weighted contrast-enhanced MR images and histopathologic features. AJNR Am J Neuroradiol 2006;27:85–93
- Weber MA, Zoubaa S, Schlieter M, et al. Diagnostic performance of spectroscopic and perfusion MRI for distinction of brain tumors. Neurology 2006;66:1899–1906, 10.1212/01.wnl.0000219767.49705.9c
- Noguchi T, Kawashima M, Irie H, et al. Arterial spin-labeling MR imaging in moyamoya disease compared with SPECT imaging. Eur J Radiol 2011;80:e557–62, 10.1016/j.ejrad.2011.01.016