Device for obtaining perfusion images

A system and method for obtaining perfusion images is disclosed. The system and method includes hardware and software for determining physiological characteristics of a patient and determining imaging parameter values for an imaging modality based on the patient's physiological characteristics. The system also includes a controller operative to receive the imaging parameter values for controlling an X-ray device. The X-ray device is coupled with the controller and acquires projection images of the patient, and outputs the projection images to a perfusion evaluation computer for evaluating the perfusion of an region of interest represented in the projection images. The perfusion rate of the region of interest is then output to an output device, such as a display or printer.

TECHNICAL FIELD

The present embodiments relate to a system and method for obtaining perfusion images. In particular, the present invention relates to a system and method for measuring a patient's physiological characteristics, and using the measured patient's physiological characteristics to compute one or more imaging parameter values for one or more imaging modalities.

BACKGROUND

The steps in planning for the treatment of blood vessels, such as brain vessels and coronary that have been altered by atherosclerosis, include the angiographic display of those blood vessels and, the quantitative calculation of the diameter, number and length of a stenosis or blockage. Besides morphological statements, such as directly visualizing a stenosis, imaging parameter values of imaging modalities are gaining increasing importance, such as for visualizing parenchymal perfusion distally of the stenosis in the event of a stroke.

Perfusion, which is the circulation of blood through tissue, is one indicator used for diagnosing an region of interest in a patient affected by a stenosis or blockage. By determining perfusion at the capillary level of the region of interest, the effect of the stenosis or blockage of an artery can be assessed and localized directly. The extent of the stenosis or blockage can also be determined. From this information, a therapeutic treatment can be planned, and its success can then be monitored immediately after the intervention by determining the perfusion of the region of interest.

Currently, there are some established perfusion imaging modalities, including positron emission tomography (“PET”), single photon emission computed tomography (“SPECT”), magnetic resonance tomography (“MRT”), or ultrasound reinforced with contrast agent. These imaging modalities offer the ability of quantifying the perfusion status of an region of interest of a patient, such as the parenchyma/myocardium. In general, these imaging modalities can be performed in cases of stable angina pectoris, chronic total blockages, or for risk stratification after a myocardial infarction or when a stroke has occurred.

In principle, the degree of perfusion of the myocardium or the parenchyma supplied by an artery can also be obtained from the data of projection-based and angiographic computed tomography. Analyzing perfusion using projection-based techniques allows for the determination of an intervention's success, and may permit supplementing or changing the therapeutic treatment in the same session.

A general principle for ascertaining the perfusion status of a patient's region of interest, such as the patient's myocardium, using an angiographic X-ray device (cardiac perfusion assessment or “TIMI blush”) is described in U.S. Pat. App. Pub. No. 2007/0041625, which is incorporated by reference herein, and U.S. Pat. App. Pub. No. 2007/0031018, which is incorporated by reference herein.

In general, contrast agent injection is done arterially into an region of interest, and is often done directly into an affected vessel. When the region of interest is captured, the amount of the contrast agent bolus present in the region of interest is often used to determine the perfusion of the region of interest. However, current systems for determining perfusion of a region of interest in a patient use fixed, predefined recording protocols.

BRIEF SUMMARY

A system and method for obtaining perfusion images is disclosed herein. The system includes a computer operative to determine one or more physiological characteristics of a patient. The system also includes another computer that receives one or more determined physiological characteristics and uses them to compute one or more imaging parameter values of one or more imaging modalities. The system further includes an X-ray device that acquires one or more projection images, such as by using angiography, representative of an region of interest of the patient using the imaging modality. Additionally, the system has a perfusion evaluation computer that determines a perfusion rate of the region of interest based on the one or more acquired projection images. One or more output devices included in the system are configured to store and display data produced by the system, including the determined physiological characteristics, the determined imaging parameter values, the one or more acquired projection images, and the perfusion rate of the region of interest determined by the perfusion evaluation computer.

The method includes measuring one or more physiological characteristics of a patient and determining one or more imaging parameter values of one or more imaging modalities using the one or more physiological characteristics. The method also includes acquiring one or more projection images representative of an region of interest of the patient using one or more imaging modalities. Furthermore, the method encompasses determining a perfusion rate of the region of interest based on the one or more acquired projection images and, finally, outputting the acquired data, such as by storing perfusion rate of the region of interest or by displaying the one or more acquired projection images.

DETAILED DESCRIPTION

FIG. 1is a block diagram of one example of a system102used to obtain perfusion images based on one or more measured physiological characteristics of a patient104. The system102includes a computer106for measuring one or more physiological characteristics of a patient104coupled with a computer108operative to compute imaging parameter values of a selected imaging modality based on the one or more measured physiological characteristics. The system102also includes a controller110operative to control an X-ray device116, and the controller110is coupled with the computer108and a perfusion evaluation computer112. The computer106, the computer108, the controller110, the perfusion evaluation computer112, or combinations thereof, are further coupled with an output device114for outputting data. A user122interacts with the system102using the computer106, the computer108, the controller110, the perfusion evaluation computer112, or combinations thereof. As shown inFIG. 1, the user122interacts with the system102using the controller110. However, the user122could interact with the system102using the computer106or other devices.

In one embodiment, the computer106, the computer108, the controller110, the perfusion computer112, the output device114, or combinations thereof are each separate devices. In an alternative embodiment, the computer106, the computer108, the controller110, the perfusion evaluation computer112, the output device114, or combinations thereof, are the same device even when listed separately. The devices shown in the system102may be connected via a wired connection, a wireless connection, or combinations thereof. The devices shown may be in the same geographic location, different geographic locations, or combinations thereof. It is also possible that each of the devices are implemented in software, hardware, or combinations thereof.

The computer106is operative to measure one or more physiological characteristics of a patient104. In general, a physiological characteristic is a measurable or non-measurable physiological condition of a patient104. Examples of physiological characteristics include, but are not limited to, cardiac output, coronary flow reserve, fractional flow reserve, heart rate, blood pressure, age, weight, race, sex, any other characteristic describing a patient104, any other now known or later learned physiological characteristics, or combinations thereof. In one embodiment, the computer106computes one or more physiological characteristics of a patient104using a parameter-based analysis, such as by receiving a predefined volumetric dataset describing region of interest of the patient104. In another embodiment, the computer106computes one or more physiological characteristics of a patient104using a direct measurement, such as by measuring the timing of a contrast bolus injected into the patient104. The computer106can also be configured to receive input from the user122, the patient104, or combinations thereof. For example, the user122could record the age of the patient104, the weight of the patient104, the sex of the patient104, any other input describing the patient104, or combinations thereof, into the computer106using an input device (not shown) coupled thereto.

As discussed above, in one embodiment, the computer106determines one or more physiological characteristics of a patient104using a parameter-based analysis. An example of a computer106that determines one or more physiological characteristics of a patient104using a parameter-based analysis is described in U.S. Pat. App. Pub. 2006/0239528, which is incorporated by reference herein. In one embodiment of a parameter-based analysis, the computer106receives a dataset describing a region of interest of a patient104, such as a dataset describing the patient's104vascular system in three-dimensions. The dataset describing the region of interest could be pre-specified to the computer106, such as on a computer-readable medium, or the dataset could be entered in by the user122, the patient104, or combinations thereof, using an input device (not shown) coupled with the computer106. In another alternative, the dataset could be acquired using the X-ray device116, or one or more imaging devices, using an imaging modality, such as angiographic computed tomography that generates volumetric datasets of a region of interest in the patient104.

Using the dataset, the computer106is then able to compute the blood flow velocity of the region of interest described by the dataset. In one embodiment, the computer106is operative to measure the blood flow velocity of the circulatory system of the patient104. Alternatively, the computer106is operative to measure the blood flow velocity of the pulmonary circulation of the patient104. In addition to the circulatory and pulmonary systems, other regions of interest include, but are not limited to, the myocardium, the gastrointestinal tract, other anatomical structures or systems, or combinations thereof.

Alternatively, or in addition to, using a dataset describing a region of interest in the patient104to compute one or more physiological characteristics, the computer106could also use an electrocardiogram, a spirometer, an electronic blood pressure monitor, any other now known or later developed patient monitoring devices, or combinations thereof, to compute one or more physiological characteristics of the patient104. In this embodiment, the patient monitoring device may be coupled to the computer106, the computer108, the perfusion evaluation computer112, the controller110, the output device114, the X-ray device116, or combinations thereof. The data acquired by the patient monitoring device, such as the blood pressure of the patient104over a period of predetermined time, is then used as input to the computer106for calculating one or more physiological characteristics of the patient104.

In another embodiment, the computer106computes one or more physiological measurements of a patient104by direct physiological measurement. In general, direct physiological measurement includes performing one or more examinations on the patient104to determine one or more physiological characteristics. For example, direct physiological measurement may include injecting the patient104with a test bolus. As disclosed herein, it should understood that the region of interest injected with the test bolus may be the same as, or different from, the region of interest where a stenosis or blockage may be located. After injecting the test bolus, the computer106then monitors the movement of the test bolus through the injected region of interest in the patient104to compute one or more physiological characteristics of the patient104. Monitoring the injected region of interest of the patient104could also be done by one or more devices coupled with the computer106, such as the perfusion evaluation computer112, the user122, or combinations thereof.

In one embodiment, monitoring of the test bolus provides information relating to the integrated flow behavior of the patient104. For example, monitoring the test bolus movement through the injected region of interest provides information relating to the blood flow velocity of the injected region of interest. In one embodiment, the computer106is configured to monitor the speed at which the test bolus passes through the injected region of interest. In this embodiment, the X-ray device116is configured to acquire one or more projection images of the injected region of interest and, based on the time taken for the test bolus to perfuse the injected region of interest from the recorded images, the relative speed of the patient's104blood flow velocity is determined. Determining the speed at which the test bolus passes through the injected region of interest may also include the use of one or more components in the system102other than the computer106and the imaging device116, such as the controller110, the computer108, the perfusion evaluation computer112, or combinations thereof. The results of monitoring the test bolus could also be output to the output device114coupled with the computer106.

In another embodiment, monitoring of the test bolus includes an evaluation of Thrombolysis in Myocardial Infarction (“TIMI”) flow grades of the injected region of interest. In general, the evaluation of TIMI flow grades are used for the assessment of coronary artery flow in acute coronary syndromes. However, the evaluation of TIMI flow grades can also be done on other injected areas of interest, including, but not limited to, the circulatory system, the pulmonary system, the gastrointestinal tract, the myocardium, other anatomical structures or systems, or combinations thereof. TIMI flow grades include a range from 0-3, where 0 represents a complete occlusion of the infarct-related artery; 1 represents some penetration of a contrast agent material beyond an obstruction but without perfusion of a distal coronary bed; 2 represents perfusion of the entire infarct vessel into the distal coronary bed, but with delayed flow compared with a normal artery; and 3 represents a full perfusion of the infarct vessel with normal blood flow. The evaluation of the TIMI flow grades may be done by the user122, by one or more components of the system102, such as the perfusion evaluation computer112, by an external device coupled with the system102, or combinations thereof. The evaluated TIMI flow grades of the injected region of interest may then be used to generate a time attenuation curve of the injected region of interest.

Alternatively, a time attenuation curve of the injected region of interest may be calculated based on the brightness of the contrast as viewed from one or more projection images representative of the injected region of interest. In this embodiment, the computer106communicates with the X-ray device116to acquire one or more projection images of the injected region of interest. The computer106then examines the same pixel from the set of acquired projection images, and by examining the brightness of the pixel as it changes over time due to the flow of the contrast through the injected region of interest, the computer106can plot and store data representative of the brightness of the pixel as a function of time. Thus, a substantially white or bright pixel would indicate a lack of contrast and a darker or substantially black pixel would indicate the presence of contrast. Accordingly, similar to the manner in which the change of TIMI flow grades assigned to the injected region of interest can be used to plot the time attenuation curve of the injected region of interest, so can the change in brightness of the selected pixel be used to plot a time attenuation curve of the injected region of interest. Using the time attenuation curve, the computer106can further determine the blood flow velocity of the injected region of interest, such as by taking the derivative of the time attenuation curve. The blood flow velocity derived from the time attenuation curve or the data used in generating the time attenuation curve is further accessible by one or more devices in the system102.

The computer108is operative to compute imaging parameter values for one or more imaging modalities based on the one or more measured physiological characteristics. The computer108can also compute one or more imaging parameter values for a previously selected imaging modality. In another embodiment, the user122can direct the computer108, such as through an input device (not shown), to compute a selected imaging parameter value for a selected imaging modality. The computer108computes the imaging parameter values of one or more imaging modalities based on a parameter-based analysis performed by the computer106, by the results of a direct physiological measurement performed on the patient104, or combinations thereof.

The imaging parameter values computed by the computer108include, but are not limited to, a time delay, the framerate of the images recorded by the X-ray device116, the amount of contrast agent to inject into the patient104, the length of time in which the contrast agent should be injected into the patient104, the length of time in which projection images are recorded, the number of projection images to be acquired by the X-ray device116of the region of interest, any other now known or later developed imaging parameter values, or combinations thereof. In one embodiment, the time delay determined by the computer108is a delay between the time in which the patient104is injected with a contrast agent and the time in which the X-ray device116begins imaging the patient104.

In one embodiment, the computer108implements a look-up table that correlates a predetermined set of values, such as imaging parameter values, with one or more physiological characteristics. Where the computer108implements a look-up table, for each physiological characteristic determined or measured by the computer106, there may be one or more imaging parameter values that correspond to the physiological characteristic. For example, given the patient's104blood flow velocity as input, the computer108uses the look-up table to calculate the time between the time in which the patient104is injected with contrast and the time in which the controller110should instruct the X-ray device116to begin recording images, and then outputs the computed time delay. The look-up table may also be populated with values that are predetermined by one or more experimental trials based on a population of patients having similar physiological characteristics. In another embodiment, the look-up table is populated with values that are computed based on one or more simulations previously performed.

In yet a further embodiment, the look-up table is modified by the computer108, by the user122, or combinations thereof, when the physiological characteristics of the patient104do not correlate to one or more imaging parameter values. For example, where the physiological characteristics of the patient104do not correlate to one or more imaging parameter values, an output on the output device114, such as an error message, may prompt the user122to enter in one or more imaging parameter values for the one or more physiological characteristics. Alternatively, the computer108may derive one or more imaging parameter values corresponding to one or more physiological characteristics based on an approximation of the values previously entered into the look-up table.

In another embodiment, the computer108is implemented as an expert system that uses one or more physiological characteristics as input to determine one or more imaging parameter values. In general, an expert system is a computer system, often implemented as a computer program, that contains a stock of rules, a set of particular facts, and a “logical engine” that allows the system to apply the supplied facts to the programmed rules to reach conclusions that can be drawn from them. In this manner, an expert system is often defined as “knowledge-based” system operative to solve problems in one or more disciplines. In one embodiment, the expert system is supplied with facts and rules relating to imaging parameter values and physiological characteristics that allow the expert system to derive one or more imaging parameter values for one or more physiological characteristics entered as input. The expert system may be further configured to communicate with the user122via the output device114, or one or more devices in the system102, where the expert system requires further information to derive one or more imaging parameter values.

In yet a further embodiment, the computer108is implemented as a neural network that uses one or more physiological characteristics as input to determine one or more imaging parameter values. In general, a neural network, or ANN (Artificial Neural Network), is designed to take a pattern of data and generalize from it, much as would the human brain, even if the data is “noisy” or incomplete. It does this in effect by a sophisticated form of trial and error, or in other words, by varying the strengths of connections between individual processing elements (analogous to neurons in the human brain) until the input yields the right output. The neural network may be initially preconfigured with a set of experimentally determined data of one or more imaging parameter values that correlate to one or more physiological characteristics. The neural network may further be configured to augment, supplement, alter, or combinations thereof, the initially preconfigured data when the computer108is supplied with one or more physiological characteristics from the computer106. The neural network may also allow the user122to augment, supplement, alter, or combinations thereof, the data representative of the associations between one or more imaging parameter values and one or more physiological characteristics.

Alternatively, or in addition to, computing one or more imaging parameter values from the parameter-based analysis of the computer106, the computer108is also configured to compute the one or more imaging parameter values from the results of the direct physiological measurement performed on the patient104. As the data representative of the time attenuation curve calculated by the computer106is accessible by the computer106, the time attenuation curve can be manipulated by the computer108to determine one or more imaging parameter values, such as through the use of the look-up table, the expert system, the neural network, or combinations thereof. For example, as the time attenuation curve is representative of the change in perfusion of an injected region of interest over time due to the introduction of a contrast agent, the computer108can use the time attenuation curve to determine the amount of contrast agent required to perfuse the injected region of interest. Additional information the computer108can derive from the time attenuation curve includes, but is not limited to, the minimum amount of contrast to inject for perfusion to occur, the maximum amount of contrast for perfusion to occur, the time taken for the contrast to perfuse the injected region of interest, the time delay between when perfusion occurs and when the contrast was first injected, any other information derivable from the time attenuation curve, or combinations thereof.

The one or more imaging parameter values determined by the computer108can be output to the output device114, such as by being displayed on a monitor, or being printed on a printer. The user122can also supplement or alter the imaging parameter values output to the output device114by one or more input devices (not shown) coupled with the computer108. For example, using a keyboard, the user122could enter in additional imaging parameter values for one or more imaging modalities.

The controller110is coupled with the computer108and operative to receive the one or more imaging parameter values from the computer108. In one embodiment, the controller110is implemented as a system controller operative to control the X-ray device116as described in U.S. Pat. App. Pub. No. 2006/0120507, which is incorporated by reference herein. When coupled with the computer108, the controller110uses the imaging parameter values received from the computer108as the imaging parameter values for one or more selected imaging modalities. Alternatively, or in addition, the controller110may use predetermined default imaging parameter values for one or more imaging parameter values where the computer108does not provide a complete set of imaging parameter values. By way of simplistic example only, an imaging modality, such as angiographic computed tomography, may require values for three imaging parameters: image quality, framerate, and scene duration. In this example, if the computer108determines an image quality value and a framerate value based on one or more physiological characteristics, but does not compute a scene duration value, the controller110may use a predetermined default scene duration value. Alternatively, the controller110may compute an imaging parameter value not determined by the computer108, or the user122may input one or more imaging parameter values to the controller110to supplement, override, or combinations thereof, the imaging parameter values provided by the computer108, the controller110, or combinations thereof.

The controller110can also receive one or more projection images recorded by the X-ray device116and store them on a storage device (not shown) coupled with the controller110, or the controller110can output the one or more projection images on the output device114. The X-ray device116includes an X-ray source118and an X-ray detector120. The patient104is positioned between the X-ray source118and the X-ray detector120, such that an region of interest can be captured in one or more projection images. The projection images recorded by the X-ray device116may be two-dimensional angiographic images, a set of projection images used to construct a three-dimensional image, or combinations thereof. For example, the X-ray device116may be configured to record projection images using traditional angiography. Alternatively, or in addition to traditional angiography, the X-ray device116may be configured to record projection images using angiographic computed tomography, whereby a set of projection images are reconstructed into a three-dimensional volumetric image as described in U.S. Pat. App. Pub. 2006/0120507.

The perfusion evaluation computer112is coupled with the controller110and operative to receive one or more projection images recorded by the X-ray device116. The perfusion evaluation computer112is further operative to evaluate the recorded projection images to determine the amount of perfusion of the region of interest recorded by the X-ray device116. The perfusion evaluation computer112is also configured to compute the perfusion rate of the region of interest. For example, and as described in U.S. Pat. App. Pub. No. 2007/0041625, the perfusion evaluation computer112can use a comparison of myocardial blush for a set of acquired projection images to determine the rate of perfusion for an region of interest. Alternatively, the user122may be trained to determine the perfusion rate of the region of interest based on assigning TIMI flow grades as previously discussed above. The perfusion rate of the region of interest can also be output to the output device114coupled with the perfusion evaluation computer112.

FIG. 2is a block diagram of one example of a computer106used to measure one or more physiological characteristics of a patient104. In one embodiment, the computer106includes an input device202coupled with an input interface204. The input interface204is further coupled with a processor206. The processor206is coupled with a storage device208, a graphics controller210, and an output interface212. The graphics controller210is also coupled with the output interface212. The output interface212is further coupled with an output device214and can communicate with one or more devices coupled with the processor206.

With reference toFIG. 1andFIG. 2, the input device202is operative to receive an input from the patient104, the user122, one or more devices coupled with the system102, or combinations thereof. The input device202may be an audio input device, a tactile input device, a memory storage device, any now known or later developed input device, or combinations thereof. In one example, the input device202is a microphone. In another example, the input device202is a keyboard, mouse, trackball, touch pad or other pointer control. In another example, the input device202is a memory storage device, such as a hard disk drive, compact disc, digital video disc, flash memory, random access memory, or combinations thereof. In yet another example, the input device202is an electrocardiogram, a spirometer, an electronic blood pressure monitor, any other known or later developed patient monitoring device, or combinations thereof.

In one embodiment, the input device202is operative to receive input for a parameter-based analysis of one or more physiological characteristics of a patient104. For example, the input device202may be a keyboard where a user122inputs one or more physiological characteristics relating to the patient104including, but not limited to, heart rate, blood pressure, age, weight, race, or sex. As an alternative example, the input device202may be a compact disc that contains a dataset describing an region of interest in the patient104, such as a dataset describing the patient's104vascular system as described in U.S. Pat. App. Pub. 2006/0239528. The input collected by the input device202is passed to the input interface204for processing by the processor206.

The input interface204coupled with the input device202is operative to receive the input collected by the input device202. The input interface202may be a wired interface, such as PS/2, USB, Ethernet, IDE/ATA, SCSI, SATA, or IEEE 1394, a wireless interface, such as 802.11 a/b/g, Bluetooth, RF, infrared, an audio interface, such as stereo, S/PDIF, AES/EBU, or combinations thereof. In one embodiment, the input interface204is a PS/2 interface coupled with the input device202, which is a keyboard. In another embodiment, the input interface204is an IDE/ATA interface and the input device202is a hard drive. In yet a further embodiment, the input interface204is an IDE/ATA interface and the input device202is a compact disc. In an alternative embodiment, the input interface204is an Ethernet interface, and the input device202is the X-ray device116.

The processor206is operative to process the information collected by the input device202. The processor206may be a general processor, a data signal processor, graphics card, graphics chip, personal computer, motherboard, memories, buffers, scan converters, filters, interpolators, field programmable gate array, application-specific integrated circuit, analog circuits, digital circuits, combinations thereof, or any other now known or later developed processor. Alternatively, or in addition, the processor206is adapted to implement software written in a computer programming language, such as BASIC, C, Dylan, Euphoria, ASP, C++, Java, Python, PHP, Javascript, any now known or later developed computer programming language, or combinations thereof.

In one embodiment, the processor206receives one or more physiological characteristics inputted by the user122and communicates with the storage device208to store them for later retrieval. In another embodiment, the processor206receives data from the input device202and calculates one or more physiological characteristics. For example, the processor206may contain software for calculating the blood flow velocity of an region of interest in the patient104using one or more volumetric datasets entered as input using the input device202that describe the region of interest. As another example, the processor206may contain software for calculating the cardiac output of the patient104using an electrocardiogram as an input device202. In yet another embodiment, the processor206is operative to calculate one or more physiological characteristics of the patient104based on a direct physiological measurement. For example, the processor206may be operative to evaluate the TIMI flow grades of an region of interest injected with a test bolus, as described in U.S. Pat. App. Pub. 2007/0041625. The processor206may further receive input from the X-ray device116, such as one or more projection images, acting as an input device202. Other components, such as the controller110, the perfusion evaluation computer112, the computer108, or combinations thereof, may further serve as one or more input devices for the computer106.

The storage device208is operative to store input received from the input device202, data processed by the processor206, data processed by the graphics controller210, or combinations thereof. The storage device208may be random access memory, cache memory, dynamic random access memory, static random access memory, flash memory, virtual memory, video memory, magnetic memory, optical memory, any known or later developed memory technology, or combinations thereof. In one embodiment, the storage device208is a hard drive. In another embodiment, the memory storage device208is a DVD+RW. In a further embodiment, the storage device208is a secure digital (SD) card, or other now known or later developed data storage device. The storage device208is further operative to allow access to stored data by one or more devices including, but not limited to, the processor206, the graphics controller210, the output device214, one or more devices of the system102, or combinations thereof.

The graphics controller210is operative to control the display of data on the output device214coupled with the processor206. In one embodiment, the graphics controller210is operative to control the display of one or more projection images acquired by the X-ray device116. In another embodiment, the graphics controller210is configured to control the display of one or more images representative of an region of interest described by a volumetric dataset processed by the processor206. The images displayed on the output device214may be two-dimensional projection images, or one or more volumetric images representative of one or more two-dimensional projection images. In another embodiment, the graphics controller210is operative to control display of one or more physiological characteristics inputted by the input device202. In one embodiment, the graphics controller210is a processor. In another embodiment, the graphics controller210is software written in a computer programming language, such as BASIC, C, Dylan, Euphoria, ASP, C++, Java, Python, PHP, Javascript, any now known or later developed computer programming language, or combinations thereof.

The output interface212facilitates the output of data by the processor206, the graphics controller210, any other device coupled with the processor306, or combinations thereof to the output device214. The output interface212may be a wired interface, such as PS/2, USB, Ethernet, IDE/ATA, SCSI, SATA, IEEE 1394, VGA, DVI, or HDMI, a wireless interface, such as 802.11 a/b/g/n, Bluetooth, RF, infrared, an audio interface, such as stereo, S/PDIF, AES/EBU, EIAJ optical, or combinations thereof.

The output device214outputs data processed by the processor206, the graphics controller210, or combinations thereof, communicated through the output interface212. The data output by the output device214may text, graphics, or combinations thereof. The output device214may be a display device such as a monitor, CRT, LCD, plasma screen, flat-panel, projector, any other now known or later developed display device, a printing device, such as a laserjet printer, a color printer, any other now known or later developed printing device, a storage device, another computer, or combinations thereof. The output device214can also be the output device114. The output device214can also be any other device of the system102, including, but not limited to, the computer108, the controller110, the X-ray device116, the perfusion evaluation computer112, the output device114, or combinations thereof.

The data output by the output device214may include one or more physiological characteristics calculated by the processor206, one or more physiological characteristics input to the input device202, one or more projection images output by the X-ray device116, one or more images, two-dimensional or otherwise, representative of an region of interest in the patient104, or combinations thereof. The output device214may also output a user interface allowing the patient104, the user122, any other device of the system102, or combinations thereof, to interact with the computer106.

FIG. 3is block diagram of one example of the computer108used to determine one or more imaging parameter values of one or more imaging modalities using the one or more physiological characteristics from the computer106. In one embodiment, the computer108includes an input device302coupled with an input interface304. The input interface304is further coupled with a processor306. The processor306is coupled with a storage device308, a graphics controller310, an imaging parameter database314, and an output interface312. The graphics controller310is also coupled with the output interface312. The output interface312is further coupled with an output device314and can communicate with one or more devices coupled with the processor306.

With reference toFIG. 1andFIG. 3, the input device302is operative to receive an input from the patient104, the user122, the computer106, or combinations thereof. The input device302may be an audio input device, a tactile input device, a memory storage device, any now known or later developed input device, or combinations thereof. In one example, the input device302is a microphone. In another example, the input device302is a keyboard, mouse, trackball, touch pad or other pointer control. In another example, the input device302is a memory storage device, such as a hard disk drive, compact disc, digital video disc, flash memory, random access memory, or combinations thereof. In yet another example, the input device302is the computer106.

In one embodiment, the input device302is operative to receive input for computing one or more imaging parameter values from a parameter-based analysis of one or more physiological characteristics of a patient104or from the results of a direct physiological measurement. For example, the input device302may be a keyboard where a user122inputs one or more physiological characteristics relating to the patient104including, but not limited to, heart rate, blood pressure, age, weight, race, or sex. As an alternative example, the input device302may be a compact disc that contains a dataset of one or more physiological characteristics of the patient104. In yet a further example, the input device302is the computer106, which communicates one or more physiological characteristics of the patient104to the computer108over a wired connection, a wireless connection, or combinations thereof.

The input interface304coupled with the input device302is operative to receive the input collected by the input device302. The input interface302may be a wired interface, such as PS/2, USB, Ethernet, IDE/ATA, SCSI, SATA, or IEEE 1394, a wireless interface, such as 802.11 a/b/g, Bluetooth, RF, infrared, an audio interface, such as stereo, S/PDIF, AES/EBU, or combinations thereof. In one embodiment, the input interface304is a PS/2 interface coupled with the input device302, which is a keyboard. In another embodiment, the input interface304is an IDE/ATA interface and the input device302is a hard drive. In yet a further embodiment, the input interface304is an IDE/ATA interface and the input device302is a compact disc. In another embodiment, the input interface304is an Ethernet interface, and the input device302is the computer106.

The processor306is operative to process the information collected by the input device302. The processor306may be a general processor, a data signal processor, graphics card, graphics chip, personal computer, motherboard, memories, buffers, scan converters, filters, interpolators, field programmable gate array, application-specific integrated circuit, analog circuits, digital circuits, combinations thereof, or any other now known or later developed processor. Alternatively, or in addition, the processor206is software written in a computer programming language, such as BASIC, C, Dylan, Euphoria, ASP, C++, Java, Python, PHP, Javascript, any now known or later developed computer programming language, or combinations thereof.

In one embodiment, the processor306receives one or more physiological characteristics from the computer106and communicates with the storage device308to store them for later retrieval. In another embodiment, the processor306receives data from the input device302and calculates one or more imaging parameter values. Calculating one or more imaging parameter values from the one or more physiological characteristics may include the use of a look-up table, a neural network, an expert system, or combinations thereof.

In another embodiment, the imaging parameter database314is implemented as multiple databases, wherein each database represents an imaging modality. In this embodiment, there may be a separate database for traditional angiography and a separate database for angiographic computed tomography. Each of the separate databases then implements one or more tables, wherein each table represents a distinct imaging parameter. For example, the tables in the database for traditional angiography may include the number of projection images to record, the framerate for a set of projection images, the amount of contrast to use (minimum or maximum), the time delay between when the patient is injected with contrast and the time to begin recording projection images of the region of interest, or combinations thereof. Accordingly, using nesting, two-dimensional or multi-dimensional tables, sub-tables, multiple databases, or combinations thereof, the computer108can implement the imaging parameter database314as a look-up table that allows for relatively fast retrieval of one or more imaging parameter values for one or more imaging modalities given one or more physiological characteristics.

In yet another embodiment, the processor306includes software that allows the user122to input the imaging parameter values using input device302where one or more imaging parameter values are not in the look-up table given an input of one or more physiological characteristics. Alternatively, or in addition, the processor306communicates with a central repository, such as over a Local Area Network, a Wide Area Network, or combinations thereof, to update the look-up table for the missing one or more imaging parameter values.

Alternatively, or in addition to implementing a look-up table, the computer108may use the imaging parameter database314as part of a neural network or expert system, as previously discussed above. In one embodiment where the computer108is implemented as an expert system, the imaging parameter database314is pre-programmed with facts and rules relating to imaging parameter values and physiological characteristics that allow the processor306to derive one or more imaging parameter values for one or more physiological characteristics entered as input from the computer106, the user122, or combinations thereof.

For example, the imaging parameter database314may be populated with a set facts relating to one or more imaging modalities, such as the number and types of imaging parameters used by the one or more imaging modalities, and a set of rules establishing a relationship between the imaging parameter values of the imaging modalities and one or more physiological characteristics that are possible for a patient. The rules of the imaging parameter database314may be goal driven using backward chaining to test whether some hypothesis is true, or data driven, using forward chaining to draw new conclusions from existing data, or combinations thereof. In this embodiment, the processor306communicates with the imaging parameter database314to derive one or more imaging parameter values using one or more physiological characteristics from the computer106, the user122, or combinations thereof, as input to the imaging parameter database314.

Alternatively, or in addition, the expert system implemented by the processor306, may include other computers, processors, databases, or combinations thereof, that are used to derive one or more imaging parameter values from one or more physiological characteristics. For example, the computer108may use one or more processors as part of the expert system used to derive imaging parameter values, or the computer108may be connected to one or more computers using a wired connection, wireless connection, or combinations thereof, as part of an expert system.

The storage device308is operative to store input received from the input device302, data processed by the processor306, data processed by the graphics controller310, or combinations thereof. The storage device is also operative to store data relating to the imaging parameter database314. The storage device308may be random access memory, cache memory, dynamic random access memory, static random access memory, flash memory, virtual memory, video memory, magnetic memory, optical memory, any known or later developed memory technology, or combinations thereof. In one embodiment, the storage device308is a hard drive. In another embodiment, the memory storage device308is a DVD+RW. In a further embodiment, the storage device308is a secure digital (SD) card, or other now known or later developed data storage device. The storage device308is further operative to allow access to stored data by one or more devices including, but not limited to, the processor306, the graphics controller310, the output device314, one or more devices of the system102, or combinations thereof.

The graphics controller310is operative to control the display of data on the output device314coupled with the processor306. In one embodiment, the graphics controller310is operative to control the display of one or more projection images acquired by the X-ray device116. In another embodiment, the graphics controller310is configured to control the display of one or more imaging parameter values calculated by the processor306. In one embodiment, the graphics controller310is a processor. In another embodiment, the graphics controller310is software written in a computer programming language, such as BASIC, C, Dylan, Euphoria, ASP, C++, Java, Python, PHP, Javascript, any now known or later developed computer programming language, or combinations thereof.

The output interface312facilitates the output of data by the processor306, the graphics controller310, any other device coupled with the processor306, or combinations thereof to the output device314. The output interface312may be a wired interface, such as PS/2, USB, Ethernet, IDE/ATA, SCSI, SATA, IEEE 1394, VGA, DVI, or HDMI, a wireless interface, such as 802.11 a/b/g/n, Bluetooth, RF, infrared, an audio interface, such as stereo, S/PDIF, AES/EBU, EIAJ optical, or combinations thereof.

The output device314outputs data processed by the processor306, the graphics controller310, or combinations thereof, communicated through the output interface312. The data output by the output device314may text, graphics, or combinations thereof. The output device314may be a display device such as a monitor, CRT, LCD, plasma screen, flat-panel, projector are other now known or later developed display device, a printing device, such as a laserjet printer, a color printer, any other now known or later developed printing device, a storage device, another computer, or combinations thereof. The output device314can also be the output device114. The output device314can also be any other device of the system102, including, but not limited to, the computer106, the controller110, the X-ray device116, the perfusion evaluation computer112, the output device114, or combinations thereof.

The data output by the output device314may include one or more imaging parameter values calculated by the processor306, one or more imaging parameter values input to the input device302, one or more projection images output by the X-ray device116, two-dimensional or otherwise, representative of an region of interest in the patient104, or combinations thereof. The output device314may also output a user interface allowing the patient104, the user122, any other device of the system102, or combinations thereof, to interact with the computer108.

FIG. 4is a flowchart of one example of obtaining perfusion images based on one or more measured physiological characteristics of a patient. With reference toFIG. 1, the user122, the computer106, or combinations thereof, measure one or more physiological characteristics of a patient104(Block402). The one or more physiological characteristics are then used by a processor to calculate or determine one or more imaging parameter values (Block404). Using the calculated imaging parameter values, the X-ray device116acquires one or more projection images using a selected imaging modality (Block406). After the one or more projection images are acquired, the controller110, the user122, or combinations thereof, may communicate with the computer108to calculate additional imaging parameter values for another imaging modality. After the one or more projection images are acquired, a perfusion rate of the region of interest is determined by the perfusion evaluation computer112, the user122, or combinations thereof (Block408).

FIG. 5is a flowchart of one example of measuring one or more physiological characteristics of a patient. Initially, the user122, the computer106, or combinations thereof, determine a measuring methodology for measuring one or more physiological characteristics of a patient104(Block502). For example, the user122, the computer106, or combinations thereof, may determine that the patient104should first undergo a parameter-based measurement, and then later, a direct physiological measurement. Alternatively, the user122, the computer106, or combinations thereof, may determine that one measuring methodology is preferable over another, such as preferring a parameter-based measurement where the patient104is unable or unwilling to undergo a direct physiological measurement. Determining which measuring methodology to perform may include receiving input from the user122, the patient104, or combinations thereof, or may include the computer106performing calculations on previously provided information.

After determining which measuring methodology to perform, the user122, the computer106, or combinations thereof, then selects the measuring methodology to perform (Block504). In one embodiment, the computer106selects a parameter-based measurement for determining one or more physiological characteristics of a patient. In this embodiment, the user122, the computer106, or combinations thereof, first selects one or more physiological characteristics to measure (Block506). For example, the computer106may communicate with the computer108to determine which physiological characteristics are needed to compute one or more imaging parameter values. Alternatively, the computer106may be preprogrammed with a set of physiological characteristics to measure as a default set of physiological characteristics. In yet another embodiment, the user122may provide the computer106with a list of physiological characteristics to measure and an order in which to measure each physiological characteristic. After selecting the physiological characteristic to measure, the computer106then measures the selected physiological characteristic (Block508). The computer106may then select and measure additional physiological characteristics. After measuring the physiological characteristic, the data representing the physiological characteristic is then output, such as by being stored in the storage device208or output to the output device114(Block510). The computer106may then prompt the user122whether to perform another measurement, such as by selecting an additional measuring methodology, or by selecting an additional physiological characteristic to measure (Block522).

Alternatively, or in addition to performing a parameter-based measurement, the computer106, the user122, or combinations thereof, may select to perform a direct physiological measurement. In one embodiment, performing a direct physiological measurement on the patient104includes injecting the patient104with a contrast agent (test bolus). In this embodiment, the computer106initially determines the amount of contrast to administer to the patient104(Block512). The user122could also determine the amount of contrast to administer to the patient104. The amount of contrast agent to inject in the patient104may be specified according to a previously established protocol, the patient's104medical history, or any other measure for determining an amount of contrast to inject into a patient, or combinations thereof.

After the amount of contrast agent is determined, an region of interest in the patient104is selected in which to inject the contrast agent (Block514). The selected region of interest may be the same, or different from, the region of interest in the patient104for which the rate of perfusion is determined. For example, where there is a stenosis in a coronary artery, the selected region of interest to inject the contrast agent may include the lower extremities of the patient104. However, in this example, the selected region of interest to inject the contrast agent may include an region of interest near the constricted coronary artery. Criteria for selecting the region of interest in which to inject the contrast agent may be based on a predefined protocol programmed into the computer106, a discretionary selection by the user122, a selection based on the health of the patient104, any other criteria used for selecting an area in which to perform an injection, or combinations thereof.

Following a determination of the region of interest in which to inject the contrast agent, the contrast agent is then injected into the patient104(Block516). The injection may be performed by the computer106, by a device coupled with the computer106, by the user122, or combinations thereof.

The contrast agent injected into the region of interest is then monitored or measured (Block518). As previously described above, monitoring of the contrast agent through the injected region of interest may include acquiring one or more projection images of the injected region of interest with the X-ray device116, evaluating TIMI flow grades of the injected region of interest, monitoring the time of perfusion of the injected region of interest, counting the number of projection images acquired by the X-ray device116, any other type of monitoring, or combinations thereof. The measurements derived from monitoring the flow of contrast agent through the injected region of interest include can be further used to generate data representative of a time attenuation curve or to determine the blood flow velocity of the injected region of interest. The measurements of the flow of the contrast agent through the injected region of interest are then output, such as by being stored in the storage device208or output to the output device214(Block520).

After the user122, the computer106, or combinations thereof, have finished determining one or more physiological characteristics and does not select to perform another measurement, the results of the one or more measuring methodologies are output (Block524). In one embodiment, the results of the one or more measuring methodologies are buffered stored in the computer106, and then output to the output device214. In an alternative embodiment, the results of the one or more measuring methodologies are transferred from the storage device208to the output device214, from the output device214to the storage device208, or combinations thereof.

Referring now toFIG. 6with reference toFIG. 1andFIG. 3, is a flowchart of one example of determining imaging parameter values of one or more imaging modalities based on measured physiological characteristics of a patient104. In one embodiment, the computer108, the user122, or combinations thereof, selects an imaging modality for the controller110to use in acquiring one or more projection images of an region of interest in the patient104(Block602). Examples of imaging modalities include traditional angiography, angiographic computed tomography, any other type of angiographic imaging modality, or combinations thereof. After selecting an imaging modality, the computer108retrieves or receives one or more physiological characteristics measured by the computer106. In one embodiment, the physiological characteristics are sent as output to the computer108after being determined. In another embodiment, the computer108requests the computer106to transmit or send one or more physiological characteristics.

Using the selected imaging modality and one or more measured physiological characteristics, the computer108determines one or more imaging parameter values for the selected imaging modality (Block606). As previously discussed above, the computer108may determine one or more imaging parameter values using a look-up table, a neural network, an expert system, or combinations thereof. In an alternative embodiment, the computer108determines one or more imaging parameter values for each of the imaging modalities supported by the controller110and the X-ray device116. For example, the computer108may determine one or more imaging parameter values for traditional angiography and for angiographic computed tomography. The determined one or more imaging parameter values are then output by the computer108(Block608). The output of the determined one or more imaging parameter values may include storing the one or more imaging parameter values on the storage device308, displaying the one or more imaging parameter values on a display device, transmitting the one or more imaging parameter values to the controller110, any other type of output, or combinations thereof.

With reference toFIG. 1,FIG. 7is a flowchart of one example of acquiring projection images of an region of interest in the patient104using the one or more determined imaging parameter values. According to the embodiment shown inFIG. 7, the user122, the controller110, or combinations thereof, initially positions the patient104on the X-ray device116(Block702). Positioning the patient104may include positioning an region of interest of the patient104between the X-ray source118and the X-ray detector120. Alternatively, where the region of interest was acquired by the X-ray device116in performing a direct physiological measurement, the user122, the controller110, or combinations thereof, may not position the patient104.

After the patient104is positioned, or while the patient104is being positioned, the controller110retrieves or receives the determined one or more imaging parameter values from the computer108for a selected imaging modality. Alternatively, the controller110retrieves or receives one or more imaging parameter values determined by the computer108for each of the imaging parameter values performable by the controller110and the X-ray device116. In one embodiment, the controller110is configured to allow the user122to select which imaging modality to use with the X-ray device116, which imaging parameter values to use with one or more imaging modalities, or combinations thereof.

When the controller110has the imaging parameter values, a determination is made whether to adjust one or more imaging parameter values (Block706). The determination may be made by the controller110based on the imaging modality selected by the user122. Alternatively, the controller110may prompt the user122to adjust one or more imaging parameter values. Adjusting one or more imaging parameter values includes, but is not limited to, increasing or decreasing the value of an imaging parameter, adding or removing an imaging parameter, re-calculating an imaging parameter value, any other type of adjustment, or combinations thereof. For example, the user122, the controller110, or combinations thereof, may determine to increase the number of projection images acquired by the X-ray device116. Alternatively, the user122, the controller110, or combinations thereof, may determine to increase the framerate of the projection images acquired by the X-ray device116. In yet a further example, the user122, the controller110, or combinations thereof, may determine to increase or decrease the time delay determined by the computer108. If a determination is made to adjust one or more imaging parameter values, the user122, the controller110, or combinations thereof, adjusts the one or more imaging parameter values (Block708).

Whether the user122, the controller110, or combinations thereof, decide to adjust one or more imaging parameter values, the user122then administers the contrast agent to the patient104(Block710). In one embodiment, the user122administers the contrast agent to the patient104by injecting the contrast agent near the region of interest. After the contrast agent has been administered to the patient104, one or more projection images712are acquired of the injected region of interest using the one or more imaging parameter values determined by the computer108. As discussed above, the one or more imaging parameter values used to acquire one or more projection images of the region of interest may have been adjusted. As the X-ray device116is acquiring the one or more projection images of the region of interest of the patient104, the one or more projection images are displayed (Block714). In one embodiment, the one or more projection images being acquired are displayed on the output device114coupled with the controller110.

After the X-ray device116has acquired one or more projection images of the region of interest according to one or more imaging parameter values, the controller110, the user122, or combinations thereof, makes a determination whether to acquire another set of one or more projection images using an alternative imaging modality (Block716). For example, where one or more projection images of the region of interest were acquired using traditional angiography, the controller110, the user122, or combinations thereof, may decide to acquire one or more projection images using angiographic computed tomography.

Where the controller110, the user122, or combinations thereof, decide to acquire one or more projection images using an alternate imaging modality, the controller110, the user122, or combinations thereof, selects an alternate imaging modality (Block602). Alternatively, the controller110, the user122, or combinations thereof, may decide to acquire another set of one or more projection images of the region of interest using the same imaging modality. For example, the controller110, the user122, or combinations thereof, may decide to acquire one or more projection images using the same imaging modality but with a different set of one or more imaging parameter values. In this example, the controller110, the user122, or combinations thereof, would be given the opportunity to adjust one or more imaging parameter values before acquiring one or more projection images of the region of interest using the same imaging modality. However, the controller110, the user122, or combinations thereof, may determine to acquire another set of one or more projection images using the same imaging modality with the same one or more imaging parameter values.

After the X-ray device116has acquired one or more projection images of the region of interest, the one or more projection images are output to the output device114, the perfusion evaluation computer112, or combinations thereof (Block718). Alternatively, each time the X-ray device116has finished acquiring one or more projection images for a selected imaging modality, the one or more projection images are output to the output device114. For example, where a first set of one or more projection images are acquired using the X-ray device116, and a second set of one or more projection images are to be acquired, the first set of one or more projection images are output to the output device114before the second set of one or more projection images are acquired. However, it is also possible that the first set of projection images is buffered stored while the second set of projection images are acquired. Outputting to the output device114includes, but is not limited to, displaying one or more projection images, storing one or more projection images, printing one or more projection images, any other now known or later developed method of output, or combinations thereof. Outputting one or more projection images of the region of interest also includes outputting data representative of one or more projection images of the region of interest.

With reference toFIG. 1,FIG. 8is a flowchart of one example of determining the perfusion rate of an region of interest in the patient104based on acquired one or more projection images. As previously described above, the evaluation of the perfusion rate of the region of interest may be performed by the user122, the perfusion evaluation computer112, or combinations thereof. In one embodiment, data representative of the one or more projection images is received by the perfusion evaluation computer112(Block802). In another embodiment, the user122views the one or more projection images on the output device114. An analysis of the one or more projection images is then performed by the user122, the perfusion evaluation computer122, or combinations thereof (Block804). In one embodiment, the analysis of the one or more projection images includes assigning TIMI flow grades to one or more projection images. In another embodiment, the analysis of the one or more projection images includes evaluating one or more pixel values for one or more pixels. In yet a further embodiment, analysis of the one or more projection images includes assigning a reference image for the one or more projection images and comparing each of the one or more projection images to the reference image. Analyzing the one or more projection images may also include outputting data to the output device114, or communicating with one or more devices in the system102.

After the analysis of the one or more projection images is complete, a perfusion rate of the region of interest represented by the one or more projection images is determined (Block806). As discussed above with reference toFIG. 1, the perfusion rate of the region of interest may be determined by the user122, the perfusion evaluation computer112, any other devices or components coupled with the system102, or combinations thereof. In one embodiment, the perfusion rate of the region of interest is output to the output device114. For example, where the output device114is a printer, the perfusion rate of the region of interest over the period in which the one or more projection images were acquired is printed as a time-series graph. Alternatively, where the output device114is a display device, the perfusion rate of the region of interest is displayed for viewing by the user122. In yet a further embodiment, the perfusion rate of the region of interest is output to the computer106, the computer108, the controller110, any other devices coupled with the system102, or combinations thereof.

The perfusion rate of the region of interest may be used to evaluate the performance of an intervention, or to further determine the location of a stenosis or blockage in the region of interest. For example, where an intervention is performed on the patient104, the perfusion rate of the region of interest can be used to determine whether the intervention was successful. In this example, if the perfusion rate of the region of interest is greater after the intervention is performed, this would indicate to the user122that the intervention was most likely successful. Similarly, if the perfusion rate of the region of interest remains unchanged before an intervention and after the intervention, this would indicate to the user122that the intervention was most likely unsuccessful. In this manner, the user122, the computer106, the computer108, the controller110, the perfusion evaluation computer112, or combinations thereof, can adjust one or more imaging parameter values to further locate a stenosis or blockage.

It is intended that the foregoing detailed description be understood as an illustration of selected forms that the invention can take and not as a definition of the invention. It is only the following claims, including all equivalents, that are intended to define the scope of this invention.