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EP-4066261-B1 - METHOD FOR ESTIMATING HEAT TRANSFER ENERGY PARAMETERS IN AN ENCEPHALON

EP4066261B1EP 4066261 B1EP4066261 B1EP 4066261B1EP-4066261-B1

Inventors

  • RANGO, Mario
  • SQUARCINA, Letizia

Dates

Publication Date
20260506
Application Date
20201126

Claims (13)

  1. Medical apparatus adapted to implement a method for estimating heat transfer energy parameters in an encephalon through discretization and numerical calculation, the method comprising the steps of: A1) acquiring composition data regarding matter distribution in the encephalon, said composition data being discretized into volumetric units; B1) acquiring cerebral temperature data regarding a temperature distribution in the encephalon, said temperature data being discretized into volumetric units; A2) calculating a thermal conductivity distribution in the encephalon as a function of said composition data, said thermal conductivity distribution being discretized into volumetric units; C) calculating a distribution of conductive heat flows in the encephalon as a function of said cerebral temperature data and of said thermal conductivity distribution, said conductive heat flow distribution being calculated through a finite volume calculation of the "general heat conduction equation", wherein said step A1 comprising associating said composition data with respective first volumetric units, wherein said step A2 comprising calculating, for each second more extensive volumetric unit with respect to said first volumetric units, each second volumetric unit containing a plurality of first volumetric units, a quantity of white and/or grey matter and/or cerebrospinal fluid contained in said second volumetric unit, said quantity of white and/or grey matter and/or cerebrospinal fluid being extrapolated from the composition data associated with first volumetric units contained in said second volumetric unit, and wherein said step B1 comprises associating with each second volumetric unit a cerebral temperature value on the basis of said cerebral temperature data, in particular, the cerebral temperature value is assigned to a central point of the respective second volumetric unit.
  2. Medical apparatus according to claim 1, wherein said composition data acquired correspond to a distribution of white matter and/or grey matter and/or cerebrospinal fluid.
  3. Medical apparatus according to claim 1 or 2, wherein said step A1 comprises performing an acquisition of magnetic resonance images of the encephalon.
  4. Medical apparatus according to one or more of the preceding claims, wherein said step B1 comprises acquiring magnetic resonance spectroscopy data of the encephalon.
  5. Medical apparatus according to one or more of the preceding claims, further comprising the steps of: A0) creating a first mesh representative of at least a part of the encephalon in which said encephalon is split into first volumetric units; B0) creating a second mesh representative of at least a part of the encephalon in which said encephalon is split into second more extensive volumetric units with respect to said first volumetric units, each second volumetric unit containing a plurality of first volumetric units.
  6. Medical apparatus according to claim 1, wherein said step A1 comprises performing an acquisition of magnetic resonance images of the encephalon and said first volumetric units correspond to voxel of said magnetic resonance images, and wherein said step B1 comprises acquiring magnetic resonance spectroscopy data of the encephalon and said second volumetric units correspond to voxel of said magnetic resonance spectroscopy.
  7. Medical apparatus according to claim 1, wherein said thermal conductivity distribution comprises a plurality of thermal conductivity values, said step A2 comprising associating each thermal conductivity value with a second volumetric unit as a function of the respective quantity of white matter and/or grey matter and/or cerebrospinal fluid.
  8. Medical apparatus according to claim 7, wherein each thermal conductivity value is calculated as a linear combination of the thermal conductivity values of the grey matter and of the white matter weighted according to a coefficient dependent on the respective quantities of matter.
  9. Medical apparatus according to claim 7 or 8, wherein the calculation of the "general heat conduction equation" of said step C is performed on said second mesh using the thermal conductivity values of said thermal conductivity distribution.
  10. Medical apparatus according to one or more of claims 5 to 9, said step C comprising overlooking the second volumetric units containing a quantity of cerebrospinal fluid greater than a predetermined threshold.
  11. Medical apparatus according to one or more of the preceding claims, further comprising the steps of: D1) acquiring flow rate data related to blood flows in the encephalon; E1) acquiring blood temperature data related to the encephalon; F) calculating a distribution of convective heat flows between the encephalon and said blood flows as a function of said flow rate data, of said blood temperature data and of cerebral temperature data; G) calculating a map of metabolic heat generation of the encephalon by means of an energy balance equation between: said distribution of conductive heat flows, said distribution of convective heat flows and said map of metabolic heat generation.
  12. Medical apparatus according to claim 11, further comprising the steps of: D2) determining a distribution of blood flow rate values as a function of said flow rate data, each flow rate value being representative of blood flow rate through a respective second volumetric unit; said step F comprising calculating a convective heat flow value for each second volumetric unit as a function of the blood flow rate value and the cerebral temperature value related to said second volumetric unit and the blood temperature data; said step G comprising calculating a rate of metabolic heat generation for each second volumetric unit as a function of the value of conductive heat flow and of the value of convective heat flow of said second volumetric unit.
  13. Medical apparatus according to one or more of claims 10 to 12, further comprising the step of: H) calculating a distribution of cerebral oxygen consumption rates as a function of at least said map of metabolic heat generation, of a reaction enthalpy between glucose and oxygen and of an energy required for separation between oxygen and haemoglobin.

Description

FIELD OF THE INVENTION The present invention relates to the field of the acquisition and processing of data for diagnostic purposes. In more detail, the present invention relates to a method for estimating energy parameters related to the heat transfer in an encephalon, in particular a non-invasive method and useful for diagnostic purposes for estimating the heat flow within the encephalon. STATE OF THE ART It is known that the temperature of the encephalon is not uniform and that there are heat flows inside the encephalon. The article by Huan Wang et al. entitled "Brain temperature and its fundamental properties: a review for clinical neuroscientists" (in Frontiers in Neuroscience, vol. 8, 8 October 2014) deals with these issues, but does not quantify or propose any calculations related to such heat flows. Different therapeutic methods envisage the monitoring of the internal temperature of the encephalon during various types of therapy, e.g. during thermal ablation for curing cancer. Currently, the monitoring of the internal temperature of the human body is prevalently performed invasively. In some circumstances such as, for example, the measurement of the temperature of the encephalon, the insertion of probes or other types of devices is considered to be too dangerous or risky. Magnetic resonance techniques have recently been developed that can estimate the temperature of internal organs such as the encephalon. Such techniques do not provide any indications regarding heat exchanges between areas internal to the encephalon ABSTRACT The general object of the present invention is to improve the prior art from one or more points of view. The invention is defined by the appended claims that form an integral part of the present description. Specifically, the estimate of conductive flows in the encephalon is performed through discretization and numerical calculation; more precisely, the thermal conductivity and temperature distribution in the encephalon is discretized and then a calculation on the finite volumes of the "general heat conduction equation" is performed. LIST OF FIGURES The present invention shall become more readily apparent from the detailed description that follows to be considered together with the accompanying drawings in which: Fig. 1 shows a schematic representation of a method according to the present description.Fig. 2 shows a distribution of conductive heat flows in a portion of encephalon that can be obtained through the performance of a method according to the present description. As can be easily understood, there are various ways of practically implementing the present invention which is defined in its main advantageous aspects in the appended claims and is not limited either to the following detailed description or to the appended claims. DETAILED DESCRIPTION The subject matter of the present invention is a method for estimating heat transfer energy parameters in an encephalon, represented visually by way of example in Fig. 1. In general, the method comprises the steps of: A1) acquiring composition data regarding matter distribution in the encephalon;B1) acquiring cerebral temperature data regarding temperature distribution in the encephalon;C1) calculating a thermal conductivity distribution in the encephalon as a function of on the composition data;C) calculating a distribution of conductive heat flows in the encephalon as a function of the cerebral temperature data and on the thermal conductivity distribution using Fourier's heat conduction equation. In this way, a quantitative estimate of the conductive heat flows is obtained. Typically, in step A1, the composition data are discretized into volumetric units. Typically, in step B1, the temperature data are discretized into volumetric units. Typically, in step A2, the thermal conductivity distribution is discretized into volumetric units. As will become clearer below, for technological reasons, the composition and temperature could be discretized into volumetric units of different sizes, still referring to the same portion of encephalon and therefore we talk about "first volumetric units" and "second volumetric units". Typically, the distribution of conductive heat flows is calculated through a finite volume calculation according to Fourier's heat conduction equation. In practice, the encephalon (or a portion of the encephalon) is split into small rectangular parallelepiped shaped volumes (the cube is a special case); if a small volume is considered, the equation is used to calculate the heat that flows from this small volume towards each of the six small volumes adjacent to its six faces; obviously, the sign of the value of the heat flow corresponds to the direction of the heat flow. Advantageously, in step A1 a distribution of white matter and/or grey matter and/or cerebrospinal fluid is associated with respective first volumetric units. Advantageously, in step B1 a cerebral temperature value is associated with each second volumet