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Diagnostic benefits of presurgical fMRI in patients with brain tumours in the primary sensorimotor cortex.

Wengenroth M, Blatow M, Guenther J, Akbar M, Tronnier VM, Stippich C - Eur Radiol (2011)

Bottom Line: FMRI-based presurgical risk assessment correlated in 88% with a positive postoperative clinical outcome.Routine presurgical FMRI allows for superior assessment of the spatial relationship between brain tumour and motor cortex compared with a very detailed analysis of structural 3D MRI, thus significantly facilitating the preoperative risk-benefit assessment and function-preserving surgery.The additional imaging time seems justified.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroradiology, University of Heidelberg Medical School, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany. martina.wengenroth@med.uni-heidelberg.de

ABSTRACT

Objectives: Reliable imaging of eloquent tumour-adjacent brain areas is necessary for planning function-preserving neurosurgery. This study evaluates the potential diagnostic benefits of presurgical functional magnetic resonance imaging (fMRI) in comparison to a detailed analysis of morphological MRI data.

Methods: Standardised preoperative functional and structural neuroimaging was performed on 77 patients with rolandic mass lesions at 1.5 Tesla. The central region of both hemispheres was allocated using six morphological and three functional landmarks.

Results: fMRI enabled localisation of the motor hand area in 76/77 patients, which was significantly superior to analysis of structural MRI (confident localisation of motor hand area in 66/77 patients; p < 0.002). FMRI provided additional diagnostic information in 96% (tongue representation) and 97% (foot representation) of patients. FMRI-based presurgical risk assessment correlated in 88% with a positive postoperative clinical outcome.

Conclusion: Routine presurgical FMRI allows for superior assessment of the spatial relationship between brain tumour and motor cortex compared with a very detailed analysis of structural 3D MRI, thus significantly facilitating the preoperative risk-benefit assessment and function-preserving surgery. The additional imaging time seems justified. FMRI has the potential to reduce postoperative morbidity and therefore hospitalisation time.

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Anatomical landmarks of the central region (24-year-old female patient). Axial sections (top): hand knob (left), thickness sign (middle), bracket sign (right). Sagittal sections (bottom): gyrus frontalis inferior (GFI, left), precentral hook (middle), pars marginalis (right). From [43]
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Fig1: Anatomical landmarks of the central region (24-year-old female patient). Axial sections (top): hand knob (left), thickness sign (middle), bracket sign (right). Sagittal sections (bottom): gyrus frontalis inferior (GFI, left), precentral hook (middle), pars marginalis (right). From [43]

Mentions: Magnetic resonance imaging (MRI) is the established standard imaging technique for brain tumours in particular because of its high-resolution multiplanar images, excellent soft tissue contrast and lack of ionising radiation. For identification of the central region several morphological landmarks are being used, however, their reliability is often compromised by large inter-individual anatomical variability, even in healthy subjects [2]. The most robust morphological landmark is the motor hand area, which represents as a characteristic dorsally oriented convexity in the precentral gyrus, the so-called “hand knob” on transverse planes or “hook sign” on sagittal planes [3–6] (Fig. 1). Other representations of the human body lack such distinct morphological correlates [7], hence their localisation is restricted to a rough estimate based on the somatotopic organisation of the primary motor and somatosensory cortices (homunculus) [8]. In addition, diagnostic inaccuracy is often prompted by infiltrative and displacing mass lesions and pathological signal alterations involving the pre- or postcentral gyrus, which can lead to extensive changes of anatomical proportions, partially or completely impeding presurgical neuroimaging. Furthermore, functional areas may be shifted by brain tumours beyond typical landmarks [9–11]. To avoid permanent damage to neurological function, identification of eloquent cortical areas plays a critical role in the presurgical planning of tumour resection [12, 13]. Intra-operative mapping of brain functions by means of electrocorticography (ECoG) or sensory-evoked potential monitoring are still considered the reference techniques [12]. However, contrary to these invasive techniques, functional magnetic resonance imaging (fMRI) offers such diagnostic information non-invasively before surgery and with justifiable clinical expenditure [13, 14]. fMRI assesses brain activity indirectly by detection of local haemodynamic changes that reflect actual neuronal activity of functional areas. The blood-oxygen-level-dependent (BOLD) technique measures function-dependent decreased desoxyhaemoglobin concentrations of activated brain areas on T2*-weighted images [15–18]. Several studies comparing BOLD-fMRI with established reference methods such as ECoG validated the reliability of presurgical localisation of the primary motor cortex [19–23]. Although presurgical localisation of the motor cortex is the most established clinical application of fMRI nowadays, employed in a continuously increasing number of clinics, there are still no consistent and uniform guidelines regarding data acquisition, analysis and medical interpretation. Additionally, only a few authors have attempted to analyse the diagnostic value of presurgical fMRI, and existing reports are mainly based on non-standardised investigations in smaller groups of patients [24–28]. The lack of large-scale presurgical fMRI studies is apparent and so far impeded further clinical implementation of this technique within the diagnostic setting prior to neurosurgery [12]. Undoubtedly, it is absolutely essential to critically evaluate diagnostic potential and clinical benefits of such a powerful preoperative imaging technique with standardised methods in a representative group. Accordingly, this study compares diagnostic benefits of presurgical fMRI with those of morphological MRI in a large number of patients with brain tumours of the central region.Fig. 1


Diagnostic benefits of presurgical fMRI in patients with brain tumours in the primary sensorimotor cortex.

Wengenroth M, Blatow M, Guenther J, Akbar M, Tronnier VM, Stippich C - Eur Radiol (2011)

Anatomical landmarks of the central region (24-year-old female patient). Axial sections (top): hand knob (left), thickness sign (middle), bracket sign (right). Sagittal sections (bottom): gyrus frontalis inferior (GFI, left), precentral hook (middle), pars marginalis (right). From [43]
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3101350&req=5

Fig1: Anatomical landmarks of the central region (24-year-old female patient). Axial sections (top): hand knob (left), thickness sign (middle), bracket sign (right). Sagittal sections (bottom): gyrus frontalis inferior (GFI, left), precentral hook (middle), pars marginalis (right). From [43]
Mentions: Magnetic resonance imaging (MRI) is the established standard imaging technique for brain tumours in particular because of its high-resolution multiplanar images, excellent soft tissue contrast and lack of ionising radiation. For identification of the central region several morphological landmarks are being used, however, their reliability is often compromised by large inter-individual anatomical variability, even in healthy subjects [2]. The most robust morphological landmark is the motor hand area, which represents as a characteristic dorsally oriented convexity in the precentral gyrus, the so-called “hand knob” on transverse planes or “hook sign” on sagittal planes [3–6] (Fig. 1). Other representations of the human body lack such distinct morphological correlates [7], hence their localisation is restricted to a rough estimate based on the somatotopic organisation of the primary motor and somatosensory cortices (homunculus) [8]. In addition, diagnostic inaccuracy is often prompted by infiltrative and displacing mass lesions and pathological signal alterations involving the pre- or postcentral gyrus, which can lead to extensive changes of anatomical proportions, partially or completely impeding presurgical neuroimaging. Furthermore, functional areas may be shifted by brain tumours beyond typical landmarks [9–11]. To avoid permanent damage to neurological function, identification of eloquent cortical areas plays a critical role in the presurgical planning of tumour resection [12, 13]. Intra-operative mapping of brain functions by means of electrocorticography (ECoG) or sensory-evoked potential monitoring are still considered the reference techniques [12]. However, contrary to these invasive techniques, functional magnetic resonance imaging (fMRI) offers such diagnostic information non-invasively before surgery and with justifiable clinical expenditure [13, 14]. fMRI assesses brain activity indirectly by detection of local haemodynamic changes that reflect actual neuronal activity of functional areas. The blood-oxygen-level-dependent (BOLD) technique measures function-dependent decreased desoxyhaemoglobin concentrations of activated brain areas on T2*-weighted images [15–18]. Several studies comparing BOLD-fMRI with established reference methods such as ECoG validated the reliability of presurgical localisation of the primary motor cortex [19–23]. Although presurgical localisation of the motor cortex is the most established clinical application of fMRI nowadays, employed in a continuously increasing number of clinics, there are still no consistent and uniform guidelines regarding data acquisition, analysis and medical interpretation. Additionally, only a few authors have attempted to analyse the diagnostic value of presurgical fMRI, and existing reports are mainly based on non-standardised investigations in smaller groups of patients [24–28]. The lack of large-scale presurgical fMRI studies is apparent and so far impeded further clinical implementation of this technique within the diagnostic setting prior to neurosurgery [12]. Undoubtedly, it is absolutely essential to critically evaluate diagnostic potential and clinical benefits of such a powerful preoperative imaging technique with standardised methods in a representative group. Accordingly, this study compares diagnostic benefits of presurgical fMRI with those of morphological MRI in a large number of patients with brain tumours of the central region.Fig. 1

Bottom Line: FMRI-based presurgical risk assessment correlated in 88% with a positive postoperative clinical outcome.Routine presurgical FMRI allows for superior assessment of the spatial relationship between brain tumour and motor cortex compared with a very detailed analysis of structural 3D MRI, thus significantly facilitating the preoperative risk-benefit assessment and function-preserving surgery.The additional imaging time seems justified.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroradiology, University of Heidelberg Medical School, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany. martina.wengenroth@med.uni-heidelberg.de

ABSTRACT

Objectives: Reliable imaging of eloquent tumour-adjacent brain areas is necessary for planning function-preserving neurosurgery. This study evaluates the potential diagnostic benefits of presurgical functional magnetic resonance imaging (fMRI) in comparison to a detailed analysis of morphological MRI data.

Methods: Standardised preoperative functional and structural neuroimaging was performed on 77 patients with rolandic mass lesions at 1.5 Tesla. The central region of both hemispheres was allocated using six morphological and three functional landmarks.

Results: fMRI enabled localisation of the motor hand area in 76/77 patients, which was significantly superior to analysis of structural MRI (confident localisation of motor hand area in 66/77 patients; p < 0.002). FMRI provided additional diagnostic information in 96% (tongue representation) and 97% (foot representation) of patients. FMRI-based presurgical risk assessment correlated in 88% with a positive postoperative clinical outcome.

Conclusion: Routine presurgical FMRI allows for superior assessment of the spatial relationship between brain tumour and motor cortex compared with a very detailed analysis of structural 3D MRI, thus significantly facilitating the preoperative risk-benefit assessment and function-preserving surgery. The additional imaging time seems justified. FMRI has the potential to reduce postoperative morbidity and therefore hospitalisation time.

Show MeSH
Related in: MedlinePlus