Related Experiment Video

Updated: Aug 6, 2026

A Murine Model of Subarachnoid Hemorrhage
07:40

A Murine Model of Subarachnoid Hemorrhage

Published on: November 21, 2013

Effect of methemoglobin formation on the MR appearance of subarachnoid hemorrhage

W G Bradley, P G Schmidt

    Radiology
    |July 1, 1985
    PubMed

    Insights

    Subarachnoid hemorrhage becomes more visible on MR images over time due to methemoglobin formation. This paramagnetic substance shortens T1 relaxation, enhancing the intensity of subarachnoid hemorrhage in scans.

    Area of Science:

    • Radiology
    • Biochemistry
    • Neuroscience

    Background:

    • Subarachnoid hemorrhage (SAH) detection on MR imaging (MRI) is challenging in acute stages.
    • SAH intensity on T1-weighted MR images increases significantly within the first week.

    Purpose of the Study:

    • To investigate the biochemical basis for the increasing MR signal intensity of subarachnoid hemorrhage over time.
    • To understand the role of blood degradation products in altering MR imaging characteristics of SAH.

    Main Methods:

    • Spectroscopic analysis of cerebrospinal fluid (CSF) with varying blood concentrations.
    • Ultraviolet-visible spectroscopy of hypoxic bloody CSF.
    • Assessment of T1 and T2 relaxation times of CSF.

    Main Results:

    • Spectroscopy did not reveal significant acute alterations in CSF T1 and T2 relaxation due to blood or lysed red blood cells.
    • Ultraviolet-visible spectroscopy identified methemoglobin in hypoxic bloody CSF after 3 days.
    • Methemoglobin's paramagnetic iron facilitates T1 relaxation.

    Conclusions:

    • Methemoglobin formation contributes to the increased MR signal intensity of subarachnoid hemorrhage over time.
    • T1 shortening by methemoglobin formation likely explains the intensifying MR appearance of SAH.
    • This mechanism may also account for intense imaging of subacute hemorrhage in other body regions.

    More Related Videos

    Double Direct Injection of Blood into the Cisterna Magna as a Model of Subarachnoid Hemorrhage10:34

    Double Direct Injection of Blood into the Cisterna Magna as a Model of Subarachnoid Hemorrhage

    Published on: August 30, 2020

    Endovascular Perforation Model for Subarachnoid Hemorrhage Combined with Magnetic Resonance Imaging (MRI)06:30

    Endovascular Perforation Model for Subarachnoid Hemorrhage Combined with Magnetic Resonance Imaging (MRI)

    Published on: December 16, 2021

    Related Concept Videos

    Hemorrhagic Stroke l: Introduction01:17

    Hemorrhagic Stroke l: Introduction

    A hemorrhagic stroke is an acute neurological event that occurs when a weakened cerebral blood vessel ruptures, allowing blood to accumulate within or around the brain. The sudden release of blood forms a focal hematoma that increases intracranial pressure, displaces neural tissue, and can obstruct cerebrospinal fluid pathways. These effects may be compounded by intraventricular extension of the hemorrhage, cerebral edema, or compression of adjacent structures, all of which contribute to...
    Hemorrhagic Stroke ll: Pathophysiology01:29

    Hemorrhagic Stroke ll: Pathophysiology

    A hemorrhagic stroke develops when a cerebral blood vessel ruptures, allowing blood to escape into the surrounding brain tissue, as in intracerebral hemorrhage (ICH), or into the subarachnoid space, as in subarachnoid hemorrhage (SAH). Because the skull is a rigid compartment, the sudden presence of extravascular blood rapidly increases intracranial pressure and compresses adjacent neural structures, leading to immediate tissue injury and impaired cerebral perfusion.Mass Effect and Primary...