Patent Application
20080027315
The following detailed description of specific embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
In the following detailed description of the embodiments, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration, and not by way of limitation, specific embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the spirit and scope of the present invention.
Referring initially to
The output from the CAD algorithm 120 can then be presented 140 on a display such as, for example, an electronic monitor as CTC imagery 110 with both the colonic fluid and rectal tube removed. This new modified CT imagery 110 will also be stored in the memory storage device 130. A user, such as a radiologist or other medical personnel, will then have access to both the modified imagery from the CAD algorithm 120 as well as the original CT imagery 110 without the electronic subtraction from the memory storage device 130. The user then has the option of toggling between the presentation 140 of the two CT imageries on the display.
In step 260, the colonic air and fluid masks of the CT imagery will then be merged to form a three-dimensional representation of the patient's colon by performing a two-dimensional analysis of the high resolution CTC imagery. The colonic air mask is resampled and smoothed to the full resolution border of the colonic lumen by appending objects that are less than approximately −300 Hounsfield Units (HU) and intersected by the dilated colonic air slice. Steps are taken to ensure that extracolonic objects are not appended including the lungs. Next the fluid mask is resampled and evaluated to ensure objects of interest are maintained. Haustral fold structures are maintained by removing objects that are less than approximately 200 HU and contained inside the convex hull mask of the fluid mask perimeter. Objects that are greater than approximately 200 HU and are intersected by the dilated fluid mask are appended into the fluid mask.
The air/fluid boundary is then evaluated in an attempt to remove noise associated with this region. This is accomplished by first median filtering to remove image artifacts. Next, a gradient is evaluated and those edges with response whose magnitude is sufficiently high are considered valid edges and are appended into the fluid mask. Next any noise in the full resolution mask, defined as objects with a row projection less than approximately three, is appended into the fluid mask.
The colonic fluid will then be electronically subtracted by the CAD algorithm in step 270 by re-randomizing the imagery corresponding to the colonic fluid to simulate colonic air. All regions of interest to the radiologist, or other medical personnel, will remain including, for example, the colonic lumen, folds, and suspect polyps. This is accomplished by performing a slice by slice calculation of the statistics, including mean and standard deviation, of the colonic air for the current CT slice. If no colonic air is present in the current CT slice, the statistics are assumed that the mean is approximately −850 HU and the standard deviation is 50. For each slice, all pixels in the colonic fluid mask on that slice are assigned a normally distributed random number from the calculated distribution. A seeded random number generator is used to enforce system predictability.
In step 270, the CAD algorithm will then explicitly segment and electronically cleanse the rectal tube from the CT imagery. The rectal tube segmentation will search for objects with positive contrast to surrounding tissue and a relatively consistent cross-sectional area through the CTC slices that are contained in and adjacent to the rectum mask. Determination of the rectum mask is part of the colonic air seedpoint generation process that was discussed above. If such an object is found, three dimensional growth will be evaluated and electronic subtraction will be performed on a slice by slice basis in a manner similar to the removal of the colonic fluid as described above. This is comprised of assigning random values from a normal distribution to the pixels associated with the rectal tube. The normal distribution is evaluated from the colonic air values on that slice or default values if no colonic air is present. Removing the rectal tube will result in lower false-positive CAD marks in the rectal tube region.
The processed CTC imagery with the colonic fluid and rectal tube removed that was produced by the CAD algorithm will then be presented and displayed to the radiologist so that the entire colon can be reviewed by the radiologist in step 280. The processed CTC imagery can be displayed on an electronic monitor or on any other method typically used for displaying CTC imagery known in the art. The processed CTC imagery is then stored in a memory storage device for later retrieval by the user or other medical personnel. The user or other medical personnel also has the option of reviewing the unprocessed CTC imagery originally stored in the memory storage device. In addition, the user or other medical personnel has also the option of toggling between displaying the processed and unprocessed CTC imagery in order to compare the CTC imagery.
It is noted that terms like “preferably,” “commonly,” “approximately”, and “typically” are not utilized herein to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the present invention.
Having described the invention in detail and by reference to specific embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. More specifically, although some aspects of the present invention are identified herein as preferred or particularly advantageous, it is understood that the present invention is not necessarily limited to these preferred aspects of the invention.
