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AJNR - American Journal of Neuroradiology

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Curved-Surface Projection: An Alternative Method for Visualizing Functional MR Imaging Results

Lukas Scheef^a, Klaus Hoenig^a, Horst Urbach^a, Hans Schild^a and Roy Koenig^a

^a From the Department of Radiology, University of Bonn, Germany

View larger version (65K): [in a new window]   FIG 1. Definition of a path along the outer curvature of the brain. After the first path is defined, additional paths can be calculated by collapsing the initial path parallel to the path gradients. Displayed are the outer (a) and the inner (b) paths, which define the reconstructed volume. The thickness of the slab to be reconstructed as curved surfaces, as well as the section thickness, can be freely chosen.

View larger version (65K): [in a new window]   FIG 2. Construction of a curved surface by means of parallel shifting of a predefined path.

View larger version (142K): [in a new window]   FIG 3. The first six reconstructed sections defined in Figure 1 are displayed (section thickness, 1 mm).

View larger version (122K): [in a new window]   FIG 4. Figure shows the result of an finger-tapping experiment on a T1-weighted reference image (block design, self-paced finger tapping of the left hand). The examination was performed in the context of presurgical evaluation of a patient after recurrence of a frontocentral astrocytoma (World Health Organization grade III) in the right hemisphere. The tumor margins reach the precentral gyrus close to the hand area of the primary motor cortex. The motor area, as detected with fMRI, is marked in white (a). The central sulcus can be identified by using five anatomic features: 1, The superior frontal sulcus ends in the precentral gyrus (b). 2, The lower part of the precentral sulcus and the inferior sulcus define the T sign (c). 3, The bracket sign defines the interception of the marginal part of the cingulate sulcus and the central sulcus close to the midline (d). 4, The omega shape of the precentral gyrus defines the hand motor area, the hand knob of the primary motor cortex (e). 5, The relative thickness of the precentral gyrus to the postcentral gyrus (pre > post) can help in identifying the central sulcus (e)

View larger version (110K): [in a new window]   FIG 5. A direct comparison of a curved reconstruction (A) with orthogonal projections (B–D). The patient was admitted with a suspected central glioma (1). The curved projection reveals the location of the glioma as being posterior to the central sulcus; this is demarked by the functional overlay (2). It can be unmistakably assigned to the inferior parietal lobulus. On orthogonal projections, the assignment was more difficult and possible only after we browsed through all three projections (paradigm: block design, self-paced finger tapping of the right hand).