We present a new algorithm, called marching cubes, that creates triangle models of constant density surfaces from 3D medical data. Using a divide-and-conquer approach to generate inter-slice connectivity, we create a case table that defines triangle topology. The algorithm processes the 3D medical data in scan-line order and calculates triangle vertices using linear interpolation. We find the gradient of the original data, normalize it, and use it as a basis for shading the models. The detail in images produced from the generated surface models is the result of maintaining the inter-slice connectivity, surface data, and gradient information present in the original 3D data. Results from computed tomography (CT), magnetic resonance (MR), and single-photon emission computed tomography (SPECT) illustrate the quality and functionality of marching cubes. We also discuss improvements that decrease processing time and add solid modeling capabilities.

/pdf/marching-cubes-a-high-resolution-3d-surface-construction-3ealswkmtb.pdf

Marching cubes: A high resolution 3D surface construction algorithm

Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

https://users.fmrib.ox.ac.uk/~jesper/papers/readgroup_071009/Ashburner07.pdf

A fast diffeomorphic image registration algorithm

http://midag.cs.unc.edu/pubs/papers/Neuroimage06_Yushkevich.pdf

User-guided 3D active contour segmentation of anatomical structures: Significantly improved efficiency and reliability

A novel approach to correcting for intensity nonuniformity in magnetic resonance (MR) data is described that achieves high performance without requiring a model of the tissue classes present. The method has the advantage that it can be applied at an early stage in an automated data analysis, before a tissue model is available. Described as nonparametric nonuniform intensity normalization (N3), the method is independent of pulse sequence and insensitive to pathological data that might otherwise violate model assumptions. To eliminate the dependence of the field estimate on anatomy, an iterative approach is employed to estimate both the multiplicative bias field and the distribution of the true tissue intensities. The performance of this method is evaluated using both real and simulated MR data.

/pdf/a-nonparametric-method-for-automatic-correction-of-intensity-4smqm7oz20.pdf

A nonparametric method for automatic correction of intensity nonuniformity in MRI data

Straightening the colon with curved cross sections: an approach to CT colonography.

Computer-assisted medical imaging technologies provide new tools for the study of congenital craniofacial deformities. Three-dimensional surface reconstructions have been developed to simplify the interpretation and improve the utility of CT scans of the head. While 3-D reconstructions initially were applied to assist clinical management of craniofacial deformities, these images now are finding utility in the study of unique anomalies, the definition of group characteristics for dysmorphic heads, the differentiation of similar phenotypes, and the documentation of the effects of cranial surgery on craniofacial growth. These findings should assist the formulation and evaluation of hypotheses regarding mechanisms of congenital malformation and deformation.

Three-dimensional surface imaging from CT scans for the study of craniofacial dysmorphology.

The Craniofacial Anatomy of Apert Syndrome

Spiral/helical computed tomography (CT) was introduced to scan an anatomical volume in a single breath-hold for better temporal resolution as compared to conventional CT. Recently, it was established that given an x-ray dose, spiral CT also allows better longitudinal high-contrast resolution due to retrospective reconstruction. In spiral CT, full scan with interpolation (FI) and half-scan with interpolation (HI) are limited by the degraded slice sensitivity profile and increased image noise, respectively. We combined these two interpolation methods for a desirable balance. This new interpolation method, FI + HI, was shown to produce 4% lower image noise standard deviation than conventional CT, without loss of longitudinal bandwidth according to one-tenth-cutoff and mean-square-root measures. The analytic model of image noise was validated in a water phantom experiment. Our findings suggest the superiority of spiral CT over conventional CT in terms of both low-contrast resolution and high-contrast resolution.

Low-contrast resolution in volumetric x-ray CT—Analytical comparison between conventional and spiral CT

Three-dimensional computed tomographic scan images of facial deformities provide information that has been useful in planning and evaluating therapy. However, the benefits of computed tomographic imaging in cosmetic plastic surgery are often insufficient to justify exposing the patient to radiation. This report describes application of an optical, noncontact, three-dimensional surface digitizer with subsecond scanning time for 360-degree examination of the human head. The resultant three-dimensional surface data are suitable for computer graphics display and manipulation, and for noncontact skin surface measurement. The scanner provides accurate and complete coverage of complex facial surfaces. This system was applied to digitization of the human head in the planning and evaluation of facial plastic surgery. The results indicate that the resulting image is accurate enough to detect subtle dimensional changes resulting from surgery, including postoperative edema and surface changes due to face-lift. This type of scanning can assist in a number of tasks performed by plastic surgeons, including collecting anthropomorphic measurements, preoperative and postoperative assessment, volume monitoring, customizing of implants, and interactive planning.

Michael W. Vannier

Papers

Straightening the colon with curved cross sections: an approach to CT colonography.

Three-dimensional surface imaging from CT scans for the study of craniofacial dysmorphology.

The Craniofacial Anatomy of Apert Syndrome

Low-contrast resolution in volumetric x-ray CT—Analytical comparison between conventional and spiral CT

Quantitative three-dimensional assessment of face-lift with an optical facial surface scanner.