US5509412A
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Magnetic resonance imaging of blood volume
Assignee: Wisconsin Alumni Research Foundation
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Filing: 1994-08-24
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Granted: 1996-04-23
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Expires: 2014-08-24
Abstract
Abstract An MRI system acquires a series of images over a course of time using an echo planar imaging pulse sequence. A susceptibility contrast agent is injected into the subject during the scan to momentarily reduce NMR signal strength from voxels with blood flow. A nonlinear regression parameter estimation process is employed to calculate blood volume at each voxel directly from the acquired NMR data.
Inventors
- 👤 Mark M. Bahn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:45
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/05; A61B5/055; G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/54; G01R33/56; G01R33/563; G01R33/28; G01R33/281; G01R33/561; G01R33/5615; G01R33/5616
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
207 words
A method for producing an NMR image which indicates blood volume within a slice in a stationary patient, the steps comprising: a) acquiring NMR data from the slice for a set of T 2 weighted images depicting the patient over a course of time; b) injecting a susceptibility contrast agent into the patient during the course of time such that the patient's blood transports the susceptibility agent through the slice as the NMR data is being acquired; c) reconstructing the set of T 2 weighted images using the acquired NMR data, each T 2 weighted image including an array of NMR signal intensity values S xy ; d) calculating a blood volume value BV at a voxel location within the slice by forming a time course NMR signal S xy (t) using the corresponding NMR signal intensity values S xy from successive T 2 weighted images and fitting a model curve defined by a set of parameters which include the blood volume BV to the time course NMR signal S xy (t) using a nonlinear regression parameter estimation process; e) repeating step d) for each voxel location in the NMR image; and f) producing the NMR image using the blood volume values BV calculated in step d).
Claim 2
Independent Claim
207 words
A method for producing an NMR image which indicates blood volume within a slice in a stationary patient, the steps comprising: a) acquiring NMR data from the slice for a set of T 2 weighted images depicting the patient over a course of time; b) injecting a susceptibility contrast agent into the patient during the course of time such that the patient's blood transports the susceptibility agent through the slice as the NMR data is being acquired; c) reconstructing the set of T 2 weighted images using the acquired NMR data, each T 2 weighted image including an array of NMR signal intensity values S xy ; d) calculating a blood volume value BV at a voxel location within the slice by forming a time course NMR signal S xy (t) using the corresponding NMR signal intensity values S xy from successive T 2 weighted images and fitting a model curve defined by a set of parameters which include the blood volume BV to the time course NMR signal S xy (t) using a nonlinear regression parameter estimation process; e) repeating step d) for each voxel location in the NMR image; and f) producing the NMR image using the blood volume values BV calculated in step d).
Claim 3
Dependent Claim
66 words
The method as recited in claim 1 in which the model curve is defined as ##EQU22## where S 0 , β, α, T a and BV are the parameters estimated by the nonlinear regression parameter estimation process, t represents time, k is a proportionality constant, TE is echo time of an NMR pulse sequence used to acquire the NMR data and Γ represents a gamma function.
Claim 4
Dependent Claim
40 words
The method as recited in claim 2 in which seed values of the parameter S 0 , β, α, T a and BV are calculated before the model curve is fit to the time course NMR signal S xy (t).
Claim 5
Dependent Claim
51 words
The method as recited in claim 3 in which the seed parameter values are calculated by fitting the model curve defined by the parameters to a time course average NMR signal S a (t) formed by calculating an average NMR signal intensity in each of said acquired T 2 weighted images.
Claim 6
Dependent Claim
37 words
The method as recited in claim 1 which includes producing a mask that indicates voxels outside the patient, and employing the mask to limit the calculation of blood volume BV to those voxels located within the patient.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-04-23 | 1999-10-23 | 2000-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-04-23 | 2003-10-23 | 2004-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-04-23 | 2007-10-23 | 2008-04-23 | $7700.00 | Window Closed / Lapsed |