Image-guided therapy of a tissue
Inventors
Tyc, Richard • Qureshi, Salman • Grant, Mark Andrew • Fernandes, Luis Filipe Silva • Carreira, Daniel Prazeres • Schellhorn, John
Assignees
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Publication Number
US-10610317-B2
Publication Date
2020-04-07
Expiration Date
Abstract
Image-guided therapy of a tissue can utilize magnetic resonance imaging (MRI) or another medical imaging device to guide an instrument within the tissue. A workstation can actuate movement of the instrument, and can actuate energy emission and/or cooling of the instrument to effect treatment to the tissue. The workstation and/or an operator of the workstation can be located outside a vicinity of an MRI device or other medical imaging device, and drive means for positioning the instrument can be located within the vicinity of the MRI device or the other medical imaging device. The instrument can be an MRI compatible laser probe that provides thermal therapy to, e.g., a tissue in a brain of a patient.
Core Innovation
A method for monitoring tissue temperature during a magnetic resonance image-guided therapy of a tissue includes obtaining a plurality of magnetic resonance images representing a tissue region within a patient, where each image includes magnetic resonance thermometry data including phase data. A volume in the patient is identified that includes a region of interest at which to apply thermal therapy and surrounding tissue that surrounds the region of interest to which thermal therapy will not be applied. The magnetic resonance thermometry data of the plurality of images are analyzed to identify one or more pixels representing pixel locations demonstrating noise, signal degradation, and temperature instability, where the computed temperatures fall within or outside of a predefined temperature tolerance.
A noise mask for the region of interest is determined so that the noise mask excludes the one or more pixel locations demonstrating the at least one of noise, signal degradation and temperature instability if the computed temperature of the pixels is outside of the predefined temperature tolerance and includes the one or more pixel locations demonstrating the at least one of noise, signal degradation and temperature instability if the computed temperature of the pixels falls within the predefined temperature tolerance. A plurality of reference points are then selected from the pixels included in the noise mask, user confirmation includes deleting and re-selecting by the user, and a 3D polynomial fit is generated from the reference points identifying locations within the surrounding tissue. Each reference point corresponds to a pixel location of the phase data having a particular phase value.
Therapy is initiated and monitored by receiving a current magnetic resonance image and adjusting the phase data of the current magnetic resonance image according to the plurality of reference points. The phase data adjustment includes determining phase drift values to correct for magnetic resonance imaging phase drift using at least a subset of reference points without considering phase data corresponding to pixel locations within the region of interest, extrapolating phase drift values into a phase map, and applying the phase map to obtain drift-adjusted phase data. Corrected phase data are calculated using corrected drift-adjusted phase data and applied to the thermometry data to obtain corrected thermometry data, from which a temperature map is calculated for the region of interest.
From the temperature map and at least one of one or more historic temperature maps and baseline data sets, a tissue damage forecast is calculated that estimates cellular damage within at least a portion of the region of interest. The method further includes presenting, on a display, a rendering of the current image including a graphical representation of temperatures in the region of interest and a graphical indication of estimated cellular damage within the portion of the region of interest, including graphical indications based on threshold mapping and contour lines.
Claims Coverage
The document identifies three independent claims (a method, a system, and a non-transitory computer readable medium) that share a core monitoring workflow and collectively define phase-drift corrected MR thermometry using noise masking and reference-point based 3D polynomial fitting, followed by temperature mapping and tissue damage forecasting with display rendering. The inventive features below are extracted per independent claim.
Noise-masked reference-point 3D polynomial phase-drift correction for MR thermometry
Prior to therapy, obtain a plurality of magnetic resonance images with magnetic resonance thermometry data including phase data, identify a volume including a region of interest and surrounding tissue, analyze pixels for noise, signal degradation, and temperature instability relative to a predefined temperature tolerance, determine a noise mask, and select reference points from the noise mask to generate a 3D polynomial fit for locations in surrounding tissue with corresponding phase values.
Phase adjustment using reference points to produce drift-adjusted thermometry and a temperature map
Initiate therapy and monitoring by receiving a current magnetic resonance image and adjusting phase data using the reference points, including determining phase drift values without considering phase data in the region of interest, extrapolating the phase drift values into a phase map, applying the phase map to obtain drift-adjusted phase data, calculating corrected drift-adjusted phase data, applying corrected phase data to thermometry data to obtain corrected thermometry data, and calculating a temperature map for the region of interest.
Tissue damage forecast of cellular damage from temperature map and baseline or historic data
Calculate a tissue damage forecast from the temperature map and at least one of one or more historic temperature maps and one or more baseline data sets, wherein the historic temperature maps or baseline data sets are derived from images captured during a previous time period, and the forecast estimates cellular damage within at least a portion of the region of interest.
MR monitoring system with display rendering of temperature maps
A system includes processing circuitry in communication with a display and a medical imaging device and instructions to obtain a plurality of magnetic resonance images with thermometry phase data, identify a region of interest and surrounding tissue, analyze pixels for noise, signal degradation, and temperature instability relative to a predefined temperature tolerance, determine a noise mask, select reference points and generate a 3D polynomial fit, initiate therapy and monitoring, adjust current image phase data using reference points to correct magnetic resonance imaging phase drift, compute corrected thermometry data and a temperature map, and present a rendering on the display including a graphical representation of temperatures in the region of interest according to the temperature map.
Non-transitory computer readable medium for eligible reference-point selection, drift correction, and tissue damage forecast rendering
A non-transitory computer readable medium includes instructions to obtain a plurality of magnetic resonance images with thermometry phase and magnitude data, identify a volume including a region of interest and surrounding tissue, analyze pixels to identify noise, signal degradation, and temperature instability relative to a predefined temperature tolerance, mark pixels as ineligible for selection as reference points if outside the predefined temperature tolerance and select from eligible pixels reference points to generate a 3D polynomial fit with confirming deleting and/or re-selecting by a user, and during monitoring receive a current magnetic resonance image, adjust phase data using the reference points to correct for magnetic resonance imaging phase drift and compute corrected thermometry data, calculate a tissue damage forecast estimating cellular damage using corrected thermometry data and historic thermometry data, and cause presentation on a display including a graphical representation of temperatures and a graphical indication of estimated cellular damage.
Across the independent claims, the main inventive features are (1) identifying noise/signal degradation/temperature instability pixels and using a noise mask and user-selected reference points to generate a 3D polynomial fit for phase drift correction, (2) adjusting current MRI phase data via a phase map to obtain drift-adjusted and corrected thermometry data and computing a temperature map for the region of interest, and (3) calculating a tissue damage forecast estimating cellular damage using temperature maps with historic and/or baseline data, together with display rendering of temperatures and estimated cellular damage.
Stated Advantages
Enables calculation of a tissue damage forecast estimating cellular damage within at least a portion of the region of interest.
Provides corrected thermometry data and a temperature map for the region of interest by correcting for magnetic resonance imaging phase drift using reference points.
Supports excluding or marking pixels for reference-point selection using noise mask and predefined temperature tolerance to handle noise, signal degradation, and temperature instability.
Provides rendering on a display including graphical representation of temperatures and a graphical indication of estimated cellular damage.
Documented Applications
MRI-guided thermal therapy monitoring for brain tissue using interstitial thermal therapy with laser probes, with real-time thermometry-based temperature monitoring and tissue damage forecasting rendered for a region of interest.
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