US 2026/0294248 A1 · SYSTEM AND METHOD FOR DETERMINING A CARDIOMYOCYTE MANGANESE ION UPTAKE RATE CONSTANT TO INDICATE A T-TUBULE DENSITY

A method for determining a cardiomyocyte manganese ion uptake rate constant in one or more regions of interest in a heart of a subject comprising:

a providing step comprising:
providing a left ventricular myocardial image slice covering one or more regions of interest taken during a first time period;
providing one or more longitudinal relaxation time weighted images of the left ventricular blood pool, in the form of a saturation recovery imaging pulse sequence with a 90 degree flip angle and a short echo time, taken during the first time period to measure an average signal intensity in blood during the first time period;
providing a hematocrit measurement;
providing an extracellular volume measurement for each of the one or more regions of interest;
an administration step comprising administering a contrast agent comprising manganese 2+ ions;
an image acquisition step comprising:
performing image acquisition of the left ventricular blood pool using a longitudinal relaxation time weighted pulse sequence, in the form of a saturation recovery pulse sequence with a 90 degree flip angle and a short echo time at a plurality of time intervals during a second time period to measure respective signal intensities in blood at the plurality of time intervals;
performing a longitudinal relaxation time map image acquisition of a left ventricular myocardial image slice covering the one or more regions of interest during a third time period;
a measurement step comprising measuring a signal intensity in blood at each of the plurality of time intervals using an image taken at a time point within said corresponding time interval;
and
a calculation step comprising:
calculating a change in a myocardial longitudinal relaxation rate for each region of interest from a baseline myocardial longitudinal relaxation rate extracted from the myocardial image slice taken during the first time period and a myocardial longitudinal relaxation rate at an end time point of an MRI examination extracted from the myocardial image slice during the third time period;
calculating a saturation recovery calibration constant from the saturation recovery imaging pulse sequence taken during the first time period and the average signal intensity in the blood, wherein calculating the saturation recovery calibration constant at the region of interest comprises using the equation:
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wherein SIblood(tBL) is the average signal intensity in blood at the first time period, TD is the trigger delay, and T1blood(tBL) is the longitudinal relaxation time in blood taken during the first time period;
and
calculating a blood longitudinal relaxation rate for each of the plurality of time intervals using respective measured signal intensities in blood at the plurality of time intervals and a relationship between signal intensity and said plurality of relaxation rates according to the equation:
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wherein SIblood(ti) is the measured signal intensity in blood at time interval ti, kSR is the saturation recovery calibration constant, and TD is trigger delay;
calculating a change in blood longitudinal relaxation rate for each of the plurality of time intervals and for the MRI examination end timepoint;
integrating over all of the changes in blood longitudinal relaxation rate for each of the plurality of time intervals;
and
using the integral over all the changes in blood longitudinal relaxation rate in conjunction with the myocardial longitudinal relaxation rate at the end time point in a proportionality relationship with a cardiomyocyte Mn2+ uptake rate constant to estimate the cardiomyocyte Mn2+ uptake rate constant for each of the one or more regions of interest;
wherein said first time period is before an administration of the contrast agent, said second time period is during and after an administration of the contrast agent, and said third time period encompasses the end timepoint of an MRI examination.

116 more elements

A system for determining a cardiomyocyte manganese 2+ ion uptake rate constant in one or more regions of interest in a heart of a subject comprising:

a database module;
a measuring module;
a calculation module;
and
computer readable media comprising instructions that, when executed on a processor, perform the tasks of:
determining a cardiomyocyte manganese 2+ ion uptake rate constant in one or more regions of interest in a heart of a subject by:
a) retrieving a myocardial image slice covering the one or more regions of interest at a first time period to retrieve a baseline myocardial longitudinal relaxation rate;
b) retrieving a myocardial image slice covering the one or more regions of interest at a third time period to retrieve an examination end time myocardial longitudinal relaxation rate;
and
c) calculating a change in a myocardial longitudinal relaxation rate at each region of interest using the baseline myocardial longitudinal relaxation rate and the examination end time myocardial longitudinal relaxation rate at respective regions of interest;
and
d) retrieving a longitudinal relaxation time map of left ventricle blood pool from the first time period to measure a baseline longitudinal relaxation time in blood;
e) retrieving an average signal intensity in the blood from the first time period, from a saturation recovery pulse sequence;
and
f) accessing a pre-performed left ventricular imaging slice covering the left ventricular blood pool using a Saturation Recovery pulse sequence with a 90 degree flip angle and a short echo time at the plurality of time intervals;
g) measuring a signal intensity in blood at each of the plurality of time intervals from Saturation Recovery pulse sequence image taken at a respective time interval;
h) calculating a saturation recovery calibration constant at the region of interest using the equation:
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wherein SIblood(tBL) is the average signal intensity in blood at the first time period, TD is the trigger delay, and T1blood(tBL) is the longitudinal relaxation time in blood taken during the first time period.
i) calculating a blood longitudinal relaxation rate for each of the plurality of time intervals using the retrieved signal intensity in blood at the corresponding plurality of time intervals, and a relationship between signal intensity and said plurality of relaxation rates according to the equation:
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wherein SIblood(t) is a signal intensity in blood at the plurality of time intervals, kSR is the saturation recovery calibration constant, and TD is trigger delay;
and
j) retrieving a blood longitudinal relaxation rate at the first time period;
and
k) calculating a change in blood longitudinal relaxation rate for each of the plurality of time intervals using the blood longitudinal relaxation rate for each of the plurality of time intervals and the blood longitudinal relaxation rate at the first time period;
l) integrating over the change in blood longitudinal relaxation rate for all time intervals;
and
m) retrieving a hematocrit value;
n) retrieving an extracellular volume for the region of interest;
and
o) calculating the manganese 2+ ion cellular uptake rate constant using a proportionality relationship between:
the change in myocardial longitudinal relaxation rate at the region of interest;
the change in blood longitudinal relaxation rate;
the hematocrit;
the extracellular volume at the region of interest;
and
the integral of the change in blood longitudinal relaxation rate for all time intervals;
wherein the first time period is before an administration of a contrast agent comprising manganese 2+ ions, the second time period is during and after the administration of the contrast agent, and the third time period encompasses an end time in the examination;
wherein the said computer readable media is distributed across at least the measuring module and the calculation module of the system;
wherein the computer readable media distributed in the measuring module is configured, when executed on the processor, to perform at least task g);
and
wherein the computer readable media distributed in the calculation module is configured, when executed on the processor, to perform at least task h), i), k) and o).

132 more elements

System and method for determining a cardiomyocyte manganese ion uptake rate constant to indicate a t-tubule density

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System and method for determining a cardiomyocyte manganese ion uptake rate constant to indicate a t-tubule density

Life of this patent

Abstract

Claims23