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Neurology India, Vol. 58, No. 6, November-December, 2010, pp. 875-876 Topic of the Issue-Editorial The clinical application of blood oxygen level-dependent echo planar imaging functional magnetic resonance imaging in the preoperative planning of neurosurgical procedures involving language-related brain regions Basant K Puri Department of Imaging, Hammersmith Hospital, London, United Kingdom Code Number: ni10250 PMID: 21150052 When, in 1991, Rosen's group at Harvard published the first quantitative determination of human brain activation using magnetic resonance imaging (MRI), he and his colleagues pointed out that "knowledge of regional cerebral hemodynamics has widespread application for both physiological research and clinical assessment because of the well-established interrelation between physiological function, energy metabolism, and localized blood supply." [1] Unfortunately, the widespread clinical application of this functional MRI (fMRI) technique for clinical assessment did not materialize during the 1990s. One difficulty was that this initial technique entailed the administration of the MRI contrast agent gadolinium-diethylenetriamine penta-acetic acid (Gd-DTPA). However, the following year the same group published a noninvasive fMRI study utilizing the endogenous BOLD (blood oxygen level-dependent) effect. [2] Another difficulty related to temporal considerations, there being a need to be able to acquire large numbers of relatively low-resolution images during fMRI data acquisition so that the subject is not asked to carry out cognitive activating tasks for long stretches of time while lying inside an MRI scanner. This difficulty has also largely been solved by means of the use of echo planar imaging (EPI), which enables fMRI data to be acquired relatively rapidly. This is based on a multi-planar sequence, originally proposed by Mansfield. [3] Sir Peter Mansfield went on to win the Nobel Prize in Physiology or Medicine (co-awarded to Paul C. Lauterbur) in 2003 for this and many other advances he had helped make in MRI. Another difficulty, which proved highly controversial during the 1990s, related to the possibility of fMRI artifacts occurring which were possibly associated with stimulus-related head motion during scanning. [4] This potential difficulty has now, happily, also largely been solved, partly through the use of head restraints (and asking subjects to keep their heads as still as possible during the scanning procedure) and partly by means of post-processing software. [5] As we approach the 20 th anniversary of the inception of fMRI, it is becoming clear that there is indeed clinical utility in utilizing BOLD EPI fMRI in cerebral mapping prior to neurosurgery. As Wu and colleagues point out in their paper, 'Functional magnetic resonance imaging (fMRI)-aided therapeutics of Chinese speech area-related lesions: screening of fMRI-stimulating mode and its clinical application', in this issue of the journal, [6] the goal of minimally invasive neurosurgery is focused on both lesion removal and the retention of neurological function, of which the preservation of language function is recognized as being of great importance as well as being complicated. [6] In their excellent study, this group recruited 10 right-handed healthy Chinese volunteers and 18 patients having left-sided cerebral lesions (mostly tumors) to undergo BOLD EPI fMRI. Cerebral regions concerned with sensory language-related function ('Wernicke's area') and motor language-related function ('Broca's area') were activated using phrase comprehension testing and reading tasks, respectively. The reading tasks included silent reading, recitation, picture naming and verbal reading. The authors then go on to give a detailed case report of how these language-function regions were avoided in a 31-year-old male patient who underwent neurosurgical resection of a left temporal lobe-based tumor, complete with preoperative and postoperative scan images. Following the operation, the patient could speak clearly, and his memory and comprehension were markedly improved. This innovative study has demonstrated the clinical utility of BOLD EPI fMRI in the preoperative planning of neurosurgical procedures involving language-related brain regions. This study clearly warrants replication, and it seems probable that this investigative technique is now set to become part of the standard workup in centers of excellence when caring for such patients. The reader is strongly encouraged to read this paper. Nineteen years after Bruce Rosen's group published their first fMRI study, it is good to see the beginnings of the fulfillment of their prescient words relating to the use of this technique for clinical assessment, as quoted above. References
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