HBM01

Human Brain Mapping, in press, 2001

Integrated Volume Visualization of Functional Image Data and Anatomical Surfaces using Normal Fusion

A generic method, called Normal Fusion, for integrated 3D visualization of functional data with surfaces extracted from anatomical image data is described.  The first part of the Normal Fusion method derives quantitative values from functional input data by sampling the latter along a path determined by the (inward) normal of a surface extracted from anatomical data; the functional information is thereby projected onto the anatomical surface independently of the viewpoint.  Fusion of the anatomical and functional information is then performed with a color encoding scheme based on the HSV model. This model is preferred over the RGB model to allow easy, rapid, and intuitive retrospective manipulation of the color encoding of the functional information in the integrated display and two possible strategies for this manipulation are explained. The results first show several clinical examples that are used to demonstrate the viability of the Normal Fusion method. These same examples are then used to evaluate the two HSV color  manipulation strategies. Furthermore, five nuclear medicine physicians used several other clinical cases to evaluate the overall approach for manipulation of the color encoded functional contribution to an integrated 3D visualization. The integrated display using the Normal Fusion technique combined with the added functionality provided by the retrospective color manipulation was highly appreciated by the clinicians and can be considered an important asset in the investigation of data from multiple modalities.

NeuroImage, 2000

Automatic Morphology-based Brain Segmentation (MBRASE) from MRI-T1 Data

A method called MBRASE (Morphology-based BRAin SEgmentation) has been developed for fully automatic segmentation of the brain from T1--weighted MR image data. The starting point is a supervised segmentation technique~\cite{Hohne92} which has proven highly effective and accurate for quantitation and visualization purposes. The proposed method automates the required user interaction, \IE, defining a seed point and a threshold range, and is based on the simple operations thresholding, erosion, and geodesic dilation. The thresholds are detected in a region growing process and are defined by connections of the brain to other tissues. The method is first evaluated on three computer simulated datasets by comparing the automated segmentations with the original distributions. The second evaluation is done on a total of 30 patient datasets, by comparing the automated segmentations with supervised segmentations carried out by a neuro-anatomy expert. The comparison between two binary segmentations is performed both quantitatively and qualitatively.  The automated segmentations are found to be accurate and robust. Consequently, the proposed method can be used as a default segmentation for quantitation and visualization of the human brain from T1--weighted MR images in routine clinical procedures.
 

Journal of Nuclear Medicine, pp 311-316, vol 40, no 2, February 1999

Integrated Visualization of Functional and Anatomic Brain Data: A Validation Study

2D SPECT display and three methods for integrated visualization of SPECT and MRI patient data are evaluated by a multi-observer study to determine whether localization of functional data can be improved by adding anatomical information to the display.
Methods: SPECT and MRI data of 30 patients were gathered and presented using four types of display; one of SPECT in isolation, two integrated 2D displays, and one integrated 3D display. Cold and hot-spots in the peripheral cortex were pre-selected and indicated on black-and-white hard copies of the image data. Nuclear medicine physicians were asked to assign the corresponding spots in the image data on the computer screen to a lobe and a gyrus, and give a confidence rating for both localizations.  Inter-observer agreement using kappa statistics and average confidence ratings were assessed to interpret the reported observations.
Results: Both the inter-observer agreement and the  confidence of the observers was larger for the integrated 2D displays  than for the 2D SPECT display.  A further increase in agreement and  confidence was witnessed with the integrated 3D display.
Conclusions: Integrated display of SPECT and MR brain images provides improved localization of cerebral blood perfusion abnormalities in the peripheral cortex in relation to the anatomy of the brain over single modality display and increases the confidence of the observer.

Journal of Nuclear Medicine, pp 624-629, vol 38, no 4, April 1997

Normal Fusion for Three-Dimensional Integrated Visualization of SPECT and Magnetic Resonance Brain Images

Multimodality visualization aims at efficiently presenting integrated information obtained from different modalities, usually combining a functional modality (SPECT, PET, fMRI) with an anatomical modality (CT, MRI).  This paper presents a technique for 3D integrated visua\-lization of SPECT and MR brain images, where MRI is used as a framework of reference for the display of the SPECT data.
Methods: A novel technique for 3D integrated visualization of functional and anatomical information, called Normal Fusion, is presented. With this technique local functional information is projected onto an anatomic structure.
Results: The Normal Fusion technique is applied to three cases of SPECT/MRI integration.  The results are presented, discussed and evaluated for clinical relevance.
Conclusions: The results for 3D integrated display of SPECT and MR brain images
indicate that the Normal Fusion technique provides a potentially comprehensive and diagnostic\-ally valuable presentation of cerebral blood perfusion in relation to the anatomy of the brain.