Evidence map›Paper›PMID 40523084›Full record

ArticleMagnetic resonance in medicine2025

Exact analytical solutions of the Bloch equation for the hyperbolic-secant and chirp pulses.

Ryan H B Smith, Donald Garwood, Michael Garwood

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Article in Magnetic resonance in medicine, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.

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3citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

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3 · Its place in the literature

Who cites it

3 citing papers in PubMed.

  1. Magnetic resonance imaging.Science advances · 2026
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4 · The record

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5 · Who and what money

Authors and funding

3 authors.

Ryan H B SmithDepartment of Radiation Oncology, University of Minnesota School of Medicine, Minneapolis, Minnesota, USA.ORCID https://orcid.org/0000-0002-9207-4108
Donald GarwoodCenter for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA.
Michael GarwoodCenter for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA.ORCID https://orcid.org/0000-0003-1578-9166

Funding

TRD4 - Ultrahigh Field Engineering and SafetyP41EB027061 · NIBIB · UNIVERSITY OF MINNESOTA · PI Gregory John Metzger, KAMIL UGURBIL · 2019 to 2026
$11.7M
Breakthrough Technology to Expedite the Democratization of High Field MRIR56EB033347 · NIBIB · UNIVERSITY OF MINNESOTA · PI GARWOOD, MICHAEL, PARKINSON, BENJAMIN JOHN · 2024 to 2024
$499k
NIBIB NIH HHS P41 EB027061NIBIB NIH HHS R56 EB033347
6 · The paper itself

Abstract

purposeTo improve the accuracy and generality of analytical solutions of the Bloch equation for the hyperbolic-secant (HS1) and chirp pulses in order to facilitate application to truncated and composite pulses and use in quantitative methods. THEORY AND

methodsPrevious analytical solutions of the Bloch equation during an HS1 pulse driving function are refined and extended in this exact solution for arbitrary initial magnetization and pulse parameters including asymmetrical truncation. An unapproximated general solution during the chirp pulse is derived in a non-spinor formulation for the first time. The solution on the extended complex plane for the square pulse is included for completeness.

resultsThe exact solutions for the HS1, chirp, and square pulses demonstrate high consistency with Runge-Kutta simulations for all included pulse and isochromat parameters. The HS1 solution is strictly more accurate than the most complete prior general solution. The analytical solution of the BIR-4 composite pulse constructed using asymmetrically truncated HS1 component pulses likewise agrees with simulation results.

conclusionThe derived analytical solutions for the Bloch equation during an HS1 or chirp pulse are exact regardless of pulse parameters and initial magnetization and precisely conform with simulations enabling their use in quantitative MRI applications and setting a foundation for the analytical consideration of relaxation and pulses in multiply rotating frames.

Indexed as

AlgorithmsImage EnhancementImage Interpretation, Computer-AssistedMagnetic Resonance ImagingComputer SimulationReproducibility of ResultsSensitivity and Specificityanalytical solutionBIR‐4Bloch equationchirphyperbolic‐secantradiofrequency pulse

Identifiers

PMID40523084
PMCPMC12393199

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.