Intraoperative optical imaging (IOI) is an experimental technique used for visualizing functional brain areas after surgical exposure of the cerebral cortex. This technique identifies areas of local changes in blood volume and oxygenation caused by stimulation of specific brain functions. The authors describe a new IOI method, including innovative data analysis, that can facilitate intraoperative functional imaging on a routine basis. To evaluate the reliability and validity of this approach, they used the new IOI method to demonstrate visualization of the median nerve area of the somatosensory cortex.
In 41 patients with tumor lesions adjacent to the postcentral gyrus, lesions were surgically removed by using IOI during stimulation of the contralateral median nerve. Optical properties of the cortical tissue were measured with a sensitive camera system connected to a surgical microscope. Imaging was performed by using 9 cycles of alternating prolonged stimulation and rest periods of 30 seconds. Intraoperative optical imaging was based on blood volume changes detected by using a filter at an isosbestic wavelength (λ = 568 nm). A spectral analysis algorithm was used to improve computation of the activity maps. Movement artifacts were compensated for by an elastic registration algorithm. For validation, intraoperative conduction of the phase reversal over the central sulcus and postoperative evaluation of the craniotomy site were used.
The new method and analysis enabled significant differentiation (p < 0.005) between functional and nonfunctional tissue. The identification and visualization of functionally intact somatosensory cortex was highly reliable; sensitivity was 94.4% and specificity was almost 100%. The surgeon was provided with a 2D high-resolution activity map within 12 minutes. No method-related side effects occurred in any of the 41 patients.
The authors' new approach makes IOI a contact-free and label-free optical technique that can be used safely in a routine clinical setup. Intraoperative optical imaging can be used as an alternative to other methods for the identification of sensory cortex areas and offers the added benefit of a high-resolution map of functional activity. It has great potential for visualizing and monitoring additional specific functional brain areas such as the visual, motor, and speech cortex. A prospective national multicenter clinical trial is currently being planned.
Abbreviations used in this paper:CCD = charge-coupled device; IOI = intraoperative optical imaging.
Address correspondence to: Stephan B. Sobottka, M.D., Department of Neurosurgery, University Hospital Carl Gustav Carus, Fetscherstrasse 74, 01307 Dresden, Germany. email: firstname.lastname@example.org.Please include this information when citing this paper: published online June 21, 2013; DOI: 10.3171/2013.5.JNS122155.
CannestraAFPouratianNForageJBookheimerSYMartinNATogaAW: Functional magnetic resonance imaging and optical imaging for dominant-hemisphere perisylvian arteriovenous malformations. Neurosurgery55:804–8142004
CannestraAF, PouratianN, ForageJ, BookheimerSY, MartinNA, TogaAW: Functional magnetic resonance imaging and optical imaging for dominant-hemisphere perisylvian arteriovenous malformations. 55:804–814, 2004)| false
GrinvaldAShohamDShmuelAGlaserDVanzettaIShtoyermanE: In-vivo optical imaging of cortical architecture and dynamics. WindhorstUJohanssonH: Modern Techniques in Neuroscience ResearchBerlinSpringer1999. 893–969
PrakashNUhlemannFShethSABookheimerSMartinNTogaAW: Current trends in intraoperative optical imaging for functional brain mapping and delineation of lesions of language cortex. Neuroimage47:Suppl 2T116–T1262009
PrakashN, UhlemannF, ShethSA, BookheimerS, MartinN, TogaAW: Current trends in intraoperative optical imaging for functional brain mapping and delineation of lesions of language cortex. 47:Suppl 2T116–T126, 2009)| false
SatoKNariaiTSasakiSYazawaIMochidaHMiyakawaN: Intraoperative intrinsic optical imaging of neuronal activity from subdivisions of the human primary somatosensory cortex. Cereb Cortex12:269–2802002
SatoK, NariaiT, SasakiS, YazawaI, MochidaH, MiyakawaN, : Intraoperative intrinsic optical imaging of neuronal activity from subdivisions of the human primary somatosensory cortex. 12:269–280, 2002)| false
SatoKNariaiTTanakaYMaeharaTMiyakawaNSasakiS: Functional representation of the finger and face in the human somatosensory cortex: intraoperative intrinsic optical imaging. Neuroimage25:1292–13012005
SatoK, NariaiT, TanakaY, MaeharaT, MiyakawaN, SasakiS, : Functional representation of the finger and face in the human somatosensory cortex: intraoperative intrinsic optical imaging. 25:1292–1301, 2005)| false
YooTSAckermanMJLorensenWESchroederWChalanaVAylwardS: Engineering and algorithm design for an image processing Api: a technical report on ITK—the Insight Toolkit. Stud Health Technol Inform85:586–5922002
YooTS, AckermanMJ, LorensenWE, SchroederW, ChalanaV, AylwardS, : Engineering and algorithm design for an image processing Api: a technical report on ITK—the Insight Toolkit. 85:586–592, 2002)| false