Skip to main content
Advertisement

Main menu

  • Home
  • Content
    • Current Issue
    • Publication Preview--Ahead of Print
    • Past Issue Archive
    • Case of the Week Archive
    • Classic Case Archive
    • Case of the Month Archive
  • For Authors
  • About Us
    • About AJNR
    • Editors
    • American Society of Neuroradiology
  • Submit a Manuscript
  • Podcasts
    • Subscribe on iTunes
    • Subscribe on Stitcher
  • More
    • Subscribers
    • Permissions
    • Advertisers
    • Alerts
    • Feedback
  • Other Publications
    • ajnr

User menu

  • Subscribe
  • Alerts
  • Log in

Search

  • Advanced search
American Journal of Neuroradiology
American Journal of Neuroradiology

American Journal of Neuroradiology

  • Subscribe
  • Alerts
  • Log in

Advanced Search

  • Home
  • Content
    • Current Issue
    • Publication Preview--Ahead of Print
    • Past Issue Archive
    • Case of the Week Archive
    • Classic Case Archive
    • Case of the Month Archive
  • For Authors
  • About Us
    • About AJNR
    • Editors
    • American Society of Neuroradiology
  • Submit a Manuscript
  • Podcasts
    • Subscribe on iTunes
    • Subscribe on Stitcher
  • More
    • Subscribers
    • Permissions
    • Advertisers
    • Alerts
    • Feedback
  • Follow AJNR on Twitter
  • Visit AJNR on Facebook
  • Follow AJNR on Instagram
  • Join AJNR on LinkedIn
  • RSS Feeds
LetterLetter

Reply

Shuzo Shintani, Shin Tsuruoka and Tatsuo Shiigai
American Journal of Neuroradiology May 1999, 20 (5) 942-943;
Shuzo Shintani
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Shin Tsuruoka
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Tatsuo Shiigai
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • Article
  • Figures & Data
  • Info & Metrics
  • References
  • PDF
Loading

We apologize that we did not perform the “gold standard” method of measuring CBF—133Xenon SPECT. Nonetheless, we think that the “hyperfixation of HMPAO” is not caused by high CBF (hyperperfusion), but occurs in an area of low to slightly high CBF where the trapping of HMPAO is enhanced. First, the HMPAO SPECTs were performed in our study (1) 4 hours (case 1), 2, 6, and 19 days (case 2), 17 days (case 3), and 5 and 16 days (case 4) after the onset of stroke, respectively. The paradoxical hyperfixation appeared in every stage in cerebral infarction: extremely acute stage (4 hours in case 1); earlier acute stage (2 days in case 2); delayed acute stage (6 days in case 2, 5 days in case 4); and subacute stage (19 days in case 2, 17 days in case 3, and 16 days in case 4).

In case 1, the radiotracer counts in the region of interest (ROI) in the area of HMPAO hyperfixation and the corresponding region of the contralateral hemisphere averaged 195.3±17.6 vs 42.7±1.4 and 145.3±10.0 vs 41.3±3.0, respectively (1). The tracer counts of ROIs in hyperfixation are four to five times higher than those of the normal region. True CBF of reperfusion hyperemia cannot be so much.

In case 2, on day 3, 2 days after the onset of stroke of the left middle cerebral artery (MCA), HMPAO SPECT showed unexpected hyperfixation in the left hemisphere (Fig 1A) during the period when the patient deteriorated to deep coma and required intubation. Clinical manifestations did not suggest recanalization in case 2 on day 3. Moreover, the HMPAO hyperfixation in the area of infarct persisted for a long time—2 days (Fig 1A), 6 days (Fig 1B), and 19 days (Fig 1C) after stroke onset. On day 13, cerebral angiography revealed normal filling of the MCAs and anterior cerebral arteries bilaterally suggesting recanalization of the left MCA. Clinical manifestations and angiographic findings suggested that recanalization occurred between day 4 and 13. Serial hyperfixations of HMPAO in case 2 were not attributed to recanalization of the vessels.

Figure1
  • Download figure
  • Open in new tab
  • Download powerpoint

FIG 1. HMPAO SPECT 2 days (A), 6 days (B), and 19 days (C) after stroke onset (Case 2).

FIG 2. Angiography shows occlusion of the temporopareital branch of the MCA (Case 3).

Likewise, in case 3, cerebral angiography revealed the occlusion of the temporoparietal branch of the left MCA without evidence of recanalization (Fig 2). We think that hyperfixation can occur in all stages of infarction, and does not appear to depend on recanalization (1).

The mechanism of HMPAO hyperfixation in infarction is not known. 99mTc-d, 1-HMPAO is the first clinically available 99mTc-labeled CBF retention tracer. The cerebral retention of 99mTc-HMPAO is believed to involve the intracellular conversion of the hydrophobic Tc-HMPAO to a species that is incapable of rapid back diffusion (2). The proposed mechanism of this conversion is thought to involve interaction of 99mTc-HMPAO with glutathione (GSH) (3). GSH is responsible for intracellular trapping. Neirinckx et al suggested the accumulation of 99mTc-meso-HMPAO was dependent more on GSH content than blood flow (4). In acute and subacute stages of cerebral infarction, increased GSH levels may result in increased HMPAO retention.

Spurious hyperfixations in cerebral infarction probably happen less in 99m Tc-ECD and Iodine-123-iodoamphetamine SPECTs than in HMPAO SPECT.

References

  1. 13.↵
    Shintani S, Tsuruoka S, Shiigai T. Paradoxical hyperfixation of HMPAO in cerebral infarction. . AJNR Am J Neuroradiol 1997;18:1905-1908
    Abstract
  2. 14.↵
    Babich JW. Technetium-99m-HMPAO retention and the role of glutathione: the debate continues. J Nucl Med 1991;32:1681-1683
    FREE Full Text
  3. 15.↵
    Neirinckx RD, Harrison RC, Foster AM,, et al. A model for the in vivo behavior of TC-99m-d, 1-HMPAO in man [Abstract]. J Nucl Med 1987;28:559
  4. 16.↵
    Neirinckx RD, Burke JF, Harrison RC,, et al. The retention mechanism of TC-99m-HMPAO: intracellular reaction with glutathione. J Nucl Cereb Blood Flow Metab 1988;9 (suppl):4-12
  • Copyright © American Society of Neuroradiology
PreviousNext
Back to top

In this issue

American Journal of Neuroradiology
Vol. 20, Issue 5
1 May 1999
  • Table of Contents
  • Index by author
Advertisement
Print
Download PDF
Email Article

Thank you for your interest in spreading the word on American Journal of Neuroradiology.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
Reply
(Your Name) has sent you a message from American Journal of Neuroradiology
(Your Name) thought you would like to see the American Journal of Neuroradiology web site.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Citation Tools
Reply
Shuzo Shintani, Shin Tsuruoka, Tatsuo Shiigai
American Journal of Neuroradiology May 1999, 20 (5) 942-943;

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Share
Reply
Shuzo Shintani, Shin Tsuruoka, Tatsuo Shiigai
American Journal of Neuroradiology May 1999, 20 (5) 942-943;
del.icio.us logo Digg logo Reddit logo Twitter logo CiteULike logo Facebook logo Google logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One

Jump to section

  • Article
    • References
  • Figures & Data
  • Info & Metrics
  • References
  • PDF

Related Articles

  • No related articles found.
  • Google Scholar

Cited By...

  • No citing articles found.
  • Crossref
  • Google Scholar

This article has not yet been cited by articles in journals that are participating in Crossref Cited-by Linking.

More in this TOC Section

  • Reply:
  • COVID-19-Associated Acute Disseminated Encephalomyelitis–Like Disease
  • Primary Angiitis of the CNS with Unremarkable Vessel Wall MR Imaging: How the “T1 Shinethrough” Effect on SWI Adds to the Detection of Gadolinium Enhancement of Small Intraparenchymal Brain Vessels
Show more LETTER

Similar Articles

Advertisement

News and Updates

  • Lucien Levy Best Research Article Award
  • Thanks to our 2020 Distinguished Reviewers
  • Press Releases

Resources

  • Evidence-Based Medicine Level Guide
  • How to Participate in a Tweet Chat
  • AJNR Podcast Archive
  • Ideas for Publicizing Your Research
  • Librarian Resources
  • Terms and Conditions

Opportunities

  • Share Your Art in Perspectives
  • Get Peer Review Credit from Publons
  • Moderate a Tweet Chat

American Society of Neuroradiology

  • Neurographics
  • ASNR Annual Meeting
  • Fellowship Portal
  • Position Statements

© 2021 by the American Society of Neuroradiology | Print ISSN: 0195-6108 Online ISSN: 1936-959X

Powered by HighWire