Oct 21, 2011
Innovation: patent applications review
A round-up of the latest international patent applications in medical imaging.
Virtual tomograph enables quantitative PET comparisons
Quantitative PET/CT measurements are highly dependent on the mapping properties of the respective tomograph. In particular, this can cause problems in multicentric medical studies that presuppose quantitative comparability of data measured by participating centres. Researchers from the University of Bern in Switzerland have developed a method that supports quantitative evaluation of image data in multicentric studies (WO/2011/123964). The method involves defining a virtual tomograph with stipulated mapping properties and determining the mapping properties of different tomographs on the basis of suitable reference measurements, possibly using a calibration phantom. Using the virtual tomograph and the determined mapping properties, the method then allows conversion and quantitatively comparable representation of the image data recorded by different systems, as though all measurements were taken by the virtual system.
Coil control generates precise magnetic fields
Elekta of Sweden has developed a method for controlling the currents of a coil assembly in order to precisely generate desired magnetic fields over a large volume (WO/2011/117471). The invention can be applied as an active compensation feature for different interference shapes in magnetoencephalography (MEG) or for the precise creation of fields and gradients in MRI. The approach is an algebraic method in which a field vector is generated for a test current in each coil. Vector and matrix algebra are applied and a linear set of equations is formed. Field components and their derivatives up to the desired order can be taken into account. Principal component analysis or independent component analysis can be applied to determine the dominant external interference components. Finally, the determined currents can be installed into a current supply unit feeding the coils of the assembly.
Digital X-ray detector delivers flexible exposure control
Carestream Health (Rochester, NY) has published details of a scheme that offers greater flexibility in the use of exposure control sensors in diagnostic imaging (WO/2011/130210). Image data are obtained that relate the position of the subject to the digital radiography detector. One or more of the detector's radiant-energy sensing elements are then assigned as exposure control sensing elements. These elements are sampled one or more times during exposure to measure the exposure directed to the subject. A signal is provided to terminate exposure when sufficient radiation has been received, as measured by the exposure control sensing elements. According to the filing, this method and apparatus allow configuration of sensors to suit the conditions of each particular X-ray exam.
Display shows ultrasound, ECG data simultaneously
A system for integrated display of ultrasound images and electrocardiography (ECG) data is presented by Philips Electronics of the Netherlands. The system displays the cardiac ultrasound image of a given view along with ECG traces relating to the heart anatomy seen in that view (WO/2011/121494). The user is able to select certain ECG lead signals for display in conjunction with specific views of the heart. ST elevation values for the ECG leads can also be shown, enabling the clinician to correlate electrical abnormalities with anatomical abnormalities seen in the ultrasound image, such as abnormal wall motion or thickening. The ST elevation values are displayed on a bull's-eye chart in the associated heart regions.
Electrode assembly offers lower-cost EIT measurement
Swiss start-up Swisstom has designed a reliable and low-cost electrode assembly for electrical impedance tomography (EIT) scanning (WO/2011/113169). The assembly includes an electrode, a current supply unit, a voltage buffer unit, a switch logic unit and lines for connecting the different elements, whereby the switch logic unit comprises at least one element of a shift register and at least one element of a second shift register. This construction allows for a sequential activation of a number of electrodes aligned, for example, on a belt-like structure. As there is no need to provide each electrode with a specific address through which it is addressed by a microprocessor, the manufacturing costs of the electrode drivers may be kept low.
MRI method enhances images of moving subjects
A team from the University Medical Center Freiburg in Germany has described an MRI method that improves the quality of MR images of moving subjects (WO/2011/127942). The first step involves forming a susceptibility model of at least part of the subject, including the body part being imaged, by using a structural MR image of the body part and/or prior knowledge of the subject's anatomy. Next, susceptibility-induced field deviations in the imaging volume are computed, using the susceptibility model and knowledge of the position and orientation of the body part at each time that an MR signal is acquired. Finally, this information is used for correction of image distortions and/or intensity modulations.
About the author
Tami Freeman is editor of medicalphysicsweb.