Patent Application
20080058613
The present invention relates to analysis of bone for determining risk of fracture and more particularly, to a system and method for conveying information pertaining to bone fracture/no fracture classification.
Osteoporosis is among the most common conditions to affect the musculoskeletal system, as well as a frequent cause of locomotor pain and disability. Osteoporosis can occur in both human and animal subjects (e.g. horses). Osteoporosis (OP) occurs in a substantial portion of the human population over the age of fifty. The National Osteoporosis Foundation estimates that as many as 44 million Americans are affected by osteoporosis and low bone mass. In 1997 the estimated cost for osteoporosis related fractures was $13 billion. That figure increased to $17 billion in 2002 and is projected to increase to $210-240 billion by 2040. Currently it is expected that one in two women over the age of 50 will suffer an osteoporosis-related fracture.
In predicting skeletal disease and osteoporosis, and particularly the risk of bone fracture, a doctor and/or a patient may be presented with a large amount of information. This information should be presented to the doctor and/or the patient in a manner that is easily understood, and in a manner that eases the therapeutic decision making process.
In accordance with one embodiment of the invention, a method of classifying fracture risk for a patient is presented. The method includes determining a fracture index of the patient. Either a fracture classification or a non-fracture classification is assigned to the patient based, at least in part, on the fracture index. A confidence level of the assigned classification is determined.
In accordance with another embodiment of the invention, a computer program product for use on a computer system for classifying fracture risk for a patient is presented. The computer program product includes a computer usable medium having computer readable program code thereon. The computer readable program code includes: computer code for determining a fracture index of the patient; computer code for determining one of a fracture classification and a non-fracture classification of the patient based, at least on the fracture index; and computer code for determining a confidence level of the determined classification.
In accordance with another embodiment of the invention, a system for classifying fracture risk for a patient is presented. The system includes a controller. The controller determines a fracture index of the patient. Either a fracture classification or a non-fracture classification of the patient is assigned by the controller based, at least on the fracture index. A confidence level of the assigned fracture classification is determined by the controller.
In related embodiments of the invention, the fracture index may be based, at least in part, on at least one of, or a combination of, bone mineral density, bone micro-structure, bone macro-anatomy, and bone biomechanics. The fracture index may be based, at least in part, on trabecular bone micro-structure. Determining one of a fracture classification and a non-fracture classification may include determining a threshold fracture index value. Determining a confidence level of the determined classification may include determining a probability of making a correct classification given the fracture index of the patient. The fracture index, the determined classification, and/or the confidence level may be displayed, or a report may be generated, that includes the fracture index, the determined classification, and/or the confidence level.
These and other embodiments of the present invention will readily occur to those of ordinary skill in the art in view of the disclosure herein.
The foregoing features of the invention will be more readily understood by reference to the following detailed description, taken with reference to the accompanying drawings, in which:
In illustrative embodiments, a system and method of classifying fracture risk for a patient is presented. The method may include, for example, determining a fracture index of the patient. Based, at least in part, on the fracture index, a fracture classification or a non-fracture classification is assigned. A confidence level of the assigned fracture classification is determined. The fracture index, the assigned fracture classification and/or the confidence level may be displayed and/or provided in a report. Details of illustrative embodiments are discussed below.
An index, such as a fracture index of the patient, is determined, step 102. Illustratively, the fracture index is a value pertinent to bone fracture risk that may be determined based, at least in part, on at least one of bone mineral density, bone micro-structure, bone macro-anatomy, and bone biomechanic parameters and/or measurements (for more detail, see, for example, U.S. application Ser. No. 10/944,478 (published application 20050148860), U.S. application Ser. No. 11/228,126 (published application 20060062442), and U.S. application Ser. No. 10,753,976 (published application 20040242987), each of which is incorporated herein by reference). In preferred embodiments, the fracture index may be a combination of bone mineral density, bone micro-structure, bone macro-anatomy, and bone biomechanic parameters and/or measurements. For example, the fracture index may be obtained from combining both macro and micro structural measurements from the femoral bone regions of hip radiographs using an algorithm defined through optimization and using cross-validation data.
Parameters and measurements that may be used in calculating the fracture index are shown in tables 1-3. As will be appreciated by those of skill in the art, the parameters and measurements shown in Tables 1, 2 and 3 are provided for illustration purposes and are not intended to be limiting. It will be apparent that the terms micro-structural parameters, micro-architecture, micro-anatomic structure, micro-structural and trabecular architecture may be used interchangeably. In addition, other parameters and measurements, ratios, derived values or indices can be used to extract quantitative and/or qualitative information without departing from the scope of the invention. See, e.g., co-owned International Application WO 02/30283, which is incorporated herein by reference, in its entirety. Extracted structures typically refer to simplified or amplified representations of features derived from images. An example would be binary images of trabecular patterns generated by background subtraction and thresholding. Another example would be binary images of cortical bone generated by applying an edge filter and thresholding. The binary images can be superimposed on gray level images to generate gray level patterns of structure of interest.
The flowchart shown in
The image is analyzed using image processing algorithms to evaluate bone micro-structure, bone density and/or bone macro-architecture.
Finally, the fracture index may be generated by combining the results from the bone micro-structure analysis, the bone density analysis and/or the bone macro-architecture analysis, optionally in combination with other risk factors. The combination may be performed, for example, using linear combinations, weighted averages or likelihood ratios.
In various embodiments of the invention, one or more measurements pertaining to, without limitation, bone mineral density, bone architecture or structure, macro-anatomy, and/or bone biomechanics, may be generated from two or more x-ray beam rotation angles. The x-rays may be generated, without limitation, by a conventional radiography unit, a conventional tomography unit (CT scan), or a digital radiography unit (e.g., digital radiography (DR) or computed radiography (CR) systems). If a DR or CR system is implemented, images may be obtained from multiple rotation angles so as to allow tomographic reconstruction.
The use of multiple x-ray beam rotation angles advantageously may be used to identify anatomical landmarks more reliably. Reproducibility may be improved. Furthermore, the use of multiple x-ray beam rotation angles may be used for semi or true three-dimensional and/or volume assessments.
Referring back to
A confidence level of the determined classification (e.g., either fracture classification or non-fracture classification) is then determined, step 106. For example, the confidence level of a fracture/no-fracture classification may be defined as the probability of making the correct classification given an index value and may be estimated from probabilities that can be directly estimated from result data (available information) by applying Bayes' theorem (see, for example, J. Berger. Statistical Decision Theory and Bayesian Analysis. Springer Series in Statistics. 1993; and A. Papoulis, S. U. Pillai. Probability Random Variables and Stochastic Processes. McGraw-Hill. Fourth Ed. 2001, each of which is incorporated by reference in its entirety):
The first term in the numerator on the right hand side of the equation 1, represents the likelihood of a given Fracture Index value, considering (conditioned to) available information in which the classification was correct. The second term in the numerator represents the probability of making a correct classification and the term in the denominator represents the probability of a given fracture index value. The terms on the right hand side of the equation may be estimated from cross-validation data (available test and validation data) assuming that the cross-validation data is representative of the target population.
There are several possible methods for estimating/defining the terms on the right hand side of equation 1 (see, for example B. W. Silverman. Density Estimation for Statistics and Data Analysis. Chapman & Hall, 1986, which incorporated herein by reference. One method for estimating the terms on the right hand side is through histograms or plots of the number of cases for which the fracture index is within each of a set of contiguous ranges of values. Another method is by assuming a specific parametric form, e.g. a Normal/Gaussian distribution, for the fracture index, and estimate the corresponding parameters from the cross-validation data.
The fracture index value, determined fracture classification, as well as the confidence level of the classification can then be shown on a display and/or included in a generated report, as shown in the plot of
The present invention may be embodied in many different forms, including, but in no way limited to, computer program logic for use with a processor (e.g., a microprocessor, microcontroller, digital signal processor, or general purpose computer), programmable logic for use with a programmable logic device (e.g., a Field Programmable Gate Array (FPGA) or other PLD), discrete components, integrated circuitry (e.g., an Application Specific Integrated Circuit (ASIC)), or any other means including any combination thereof.
Computer program logic implementing all or part of the functionality previously described herein may be embodied in various forms, including, but in no way limited to, a source code form, a computer executable form, and various intermediate forms (e.g., forms generated by an assembler, compiler, linker, or locator.) Source code may include a series of computer program instructions implemented in any of various programming languages (e.g., an object code, an assembly language, or a high-level language such as Fortran, C, C++, JAVA, or HTML) for use with various operating systems or operating environments. The source code may define and use various data structures and communication messages. The source code may be in a computer executable form (e.g., via an interpreter), or the source code may be converted (e.g., via a translator, assembler, or compiler) into a computer executable form.
The computer program may be fixed in any form (e.g., source code form, computer executable form, or an intermediate form) either permanently or transitorily in a tangible storage medium, such as a semiconductor memory device (e.g., a RAM, ROM, PROM, EEPROM, or Flash-Programmable RAM), a magnetic memory device ( e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM), a PC card (e.g., PCMCIA card), or other memory device. The computer program may be fixed in any form in a signal that is transmittable to a computer using any of various communication technologies, including, but in no way limited to, analog technologies, digital technologies, optical technologies, wireless technologies, networking technologies, and internetworking technologies. The computer program may be distributed in any form as a removable storage medium with accompanying printed or electronic documentation (e.g., shrink wrapped software or a magnetic tape), preloaded with a computer system (e.g., on system ROM or fixed disk), or distributed from a server or electronic bulletin board over the communication system (e.g., the Internet or World Wide Web.)
Hardware logic (including programmable logic for use with a programmable logic device) implementing all or part of the functionality previously described herein may be designed using traditional manual methods, or may be designed, captured, simulated, or documented electronically using various tools, such as Computer Aided Design (CAD), a hardware description language (e.g., VHDL or AHDL), or a PLD programming language (e.g., PALASM, ABEL, or CUPL.)
Although various exemplary embodiments of the invention have been disclosed, it should be apparent to those skilled in the art that various changes and modifications can be made which will achieve some of the advantages of the invention without departing from the true scope of the invention. These and other obvious modifications are intended to be covered by the appended claims.
This application claims the benefit of U.S. Application Ser. No. 60/825,764, filed Sep. 15, 2006. This application is also a continuation-in-part of U.S. application Ser. No. 10/944,478, filed Sep. 17, 2004, which in turn claims the benefit of U.S. provisional application Ser. No. 60/503,916, filed Sep. 19, 2003. This application is also a continuation-in-part of U.S. application Ser. No. 11/228,126, filed Sep. 16, 2005, which in turn claims the benefit of U.S. provisional application Ser. No. 60/610,447, filed Sep. 16, 2004. Each of the above-described documents is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60825764 | Sep 2006 | US | |
| 60503916 | Sep 2003 | US | |
| 60610447 | Sep 2004 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10944478 | Sep 2004 | US |
| Child | 11855939 | Sep 2007 | US |
| Parent | 11228126 | Sep 2005 | US |
| Child | 11855939 | Sep 2007 | US |
