Normative Data for Brainstem Structures, the Midbrain-to-Pons Ratio, and the Magnetic Resonance Parkinsonism Index.

BACKGROUND AND PURPOSE: Imaging biomarkers derived from different brainstem structures are suggested to differentiate among parkinsonian disorders, but clinical implementation requires normative data. The main objective was to establish high-quality, sex-specific data for relevant brainstem structures derived from MR imaging in healthy subjects from the general population in their sixth and seventh decades of life. MATERIALS AND METHODS: 3D T1WI acquired on the same 1.5T scanner of 996 individuals (527 women) between 50 and 66 years of age from a prospective population study was used. The area of the midbrain and pons and the widths of the middle cerebellar peduncles and superior cerebellar peduncles were measured, from which the midbrain-to-pons ratio and Magnetic Resonance Parkinsonism Index [MRPI = (Pons Area / Midbrain Area) × (Middle Cerebellar Peduncles / Superior Cerebellar Peduncles)] were calculated. Sex differences in brainstem measures and correlations to age, height, weight, and body mass index were investigated. RESULTS: Inter- and intrareliability for measuring the different brainstem structures showed good-to-excellent reliability (intraclass correlation coefficient = 0.785-0.988). There were significant sex differences for the pons area, width of the middle cerebellar peduncles and superior cerebellar peduncles, midbrain-to-pons ratio, and MRPI (all, P < .001; Cohen D = 0.44-0.98), but not for the midbrain area (P = .985). There were significant very weak-to-weak correlations between several of the brainstem measures and age, height, weight, and body mass index in both sexes. However, no systematic difference in distribution caused by these variables was found, and because age had the highest and most consistent correlations, age-/sex-specific percentiles for the brainstem measures were created. CONCLUSIONS: We present high-quality, sex-specific data and age-/sex-specific percentiles for the mentioned brainstem measures. These normative data can be implemented in the neuroradiologic work-up of patients with suspected brainstem atrophy to avoid the risk of misdiagnosis.

Integrated pre- and intraoperative imaging in a patient with an arteriovenous malformation located in eloquent cortex.

INTRODUCTION: The use of integrated pre- and intraoperative imaging may be useful when resecting brain lesions in close proximity to eloquent areas, such as the primary motor cortex and language cortices. CASE REPORT: A 32-year-old woman with an arteriovenous malformation (AVM) located in the primary motor cortex underwent surgery using functional neuronavigation. Blood-oxygenation-level-dependent functional magnetic resonance imaging (BOLD fMRI) and diffusion tensor tractography (DTT) were used for preoperative mapping of primary motor areas and the corticospinal tracts, respectively. The BOLD fMRI activations and DTT tractograms were integrated into the neuronavigation system and visualized intraoperatively throughout the operation. Furthermore, stereoscopic visualizations of the angioarchitecture based on 3D MRI angiograms were used to rehearse the surgical approach to the feeder vessels. Finally, intraoperative ultrasound was used to locate and clip the feeding vessels. CONCLUSION: The AVM was carefully resected with the aid of the above-mentioned imaging techniques, and the intuitive usefulness of the techniques was further substantiated by the rewarding postoperative outcome.

Surgical resection of high-grade gliomas in eloquent regions guided by blood oxygenation level dependent functional magnetic resonance imaging, diffusion tensor tractography, and intraoperative navigated 3D ultrasound.

OBJECTIVE: The aims of this study of patients with high-grade gliomas in eloquent brain areas were 1) to assess the postoperative functional outcome, 2) to determine the extent of tumour resection in these difficult locations, 3) to evaluate the practical usefulness of navigated blood oxygenation level-dependent functional magnetic resonance imaging and diffusion tensor tractography. PATIENTS AND METHODS: 25 consecutive patients were included in the study. The patients' gross functional neurological status was determined using the 7-step modified Rankin scale. The extent of tumour resection was determined using pre- and postoperative T(1)-weighted or T(1)-weighted, contrast-enhanced MRI images. RESULTS: The average preoperative modified Rankin scale was 1.56+/-0.77, whereas the average postoperative modified Rankin scale was 1.08+/-1.29. There was a significant improvement in mean modified Rankin scale score after surgery. The mean percentage of residual tumour was calculated to 16+/-22% of the original tumour volume (median 8%). Blood oxygenation level-dependent functional magnetic resonance imaging and diffusion tensor tractography were performed in 23 and 18 patients, respectively. Blood oxygenation level-dependent functional magnetic resonance imaging and diffusion tensor tractography facilitated identification of probable functional regions in 91% and 94% of the respective investigations. CONCLUSION: We feel that the combination of blood oxygenation level-dependent functional magnetic resonance imaging, diffusion tensor tractography, and 3D ultrasound facilitated maximal tumour resection with minimal deficits. The method permits an image-based functional monitoring of the brain during surgery that may aid the preservation of motor and language function.

A growth in bipolar disorder?

OBJECTIVE: This case report suggests that screening of patients with psychiatric symptoms using modern neuroimaging can help identify organic causes of mental illness. METHOD: A single case study was reported. RESULTS: We report the case of a 25-year-old woman with a recent diagnosis of bipolar II disorder having an magnetic resonance imaging (MRI) scan as part of a research project that reveals an intraventricular brain tumour. The latter is most likely the cause of her irritability and 'hypomanic' symptoms and is defined anatomically using diffusion tensor imaging and structural and functional imaging using MRI and positron emission tomography. CONCLUSION: The lesion in this individual case most probably produces mood symptoms by impinging upon the fornix, a component of the limbic system. However, more generally, the increase in diagnosis of bipolar disorder has to be tempered against alternate causes of similar symptoms and necessitates vigilance of potential organic mechanisms.

Functional neuronavigation combined with intra-operative 3D ultrasound: initial experiences during surgical resections close to eloquent brain areas and future directions in automatic brain shift compensation of preoperative data.

OBJECTIVE: The aims of this study were: 1) To develop protocols for, integration and assessment of the usefulness of high quality fMRI (functional magnetic resonance imaging) and DTI (diffusion tensor imaging) data in an ultrasound-based neuronavigation system. 2) To develop and demonstrate a co-registration method for automatic brain-shift correction of pre-operative MR data using intra-operative 3D ultrasound. METHODS: Twelve patients undergoing brain surgery were scanned to obtain structural and fMRI data before the operation. In six of these patients, DTI data was also obtained. The preoperative data was imported into a commercial ultrasound-based navigation system and used for surgical planning and guidance. Intra-operative ultrasound volumes were acquired when needed during surgery and the multimodal data was used for guidance and resection control. The use of the available image information during planning and surgery was recorded. An automatic voxel-based registration method between preoperative MRA and intra-operative 3D ultrasound angiography (Power Doppler) was developed and tested postoperatively. RESULTS: The study showed that it is possible to implement robust, high-quality protocols for fMRI and DTI and that the acquired data could be seamlessly integrated in an ultrasound-based neuronavigation system. Navigation based on fMRI data was found to be important for pre-operative planning in all twelve procedures. In five out of eleven cases the data was also found useful during the resection. DTI data was found to be useful for planning in all five cases where these data were imported into the navigation system. In two out of four cases DTI data was also considered important during the resection (in one case DTI data were acquired but not imported and in another case fMRI and DTI data could only be used for planning). Information regarding the location of important functional areas (fMRI) was more beneficial during the planning phase while DTI data was more helpful during the resection. Furthermore, the surgeon found it more user-friendly and efficient to interpret fMRI and DTI information when shown in a navigation system as compared to the traditional display on a light board or monitor. Updating MRI data for brain-shift using automatic co-registration of preoperative MRI with intra-operative ultrasound was feasible. CONCLUSION: In the present study we have demonstrated how both fMRI and DTI data can be acquired and integrated into a neuronavigation system for improved surgical planning and guidance. The surgeons reported that the integration of fMRI and DTI data in the navigation system represented valuable additional information presented in a user-friendly way and functional neuronavigation is now in routine use at our hospital. Furthermore, the present study showed that automatic ultrasound-based updates of important pre-operative MRI data are feasible and hence can be used to compensate for brain shift.