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<meta name="DC.Title" content="Predictive Value of Noncontrast Head CT with Negative Findings in the Emergency Department Setting" />
<meta name="DC.Identifier" content="10.3174/ajnr.A6408" />
<meta name="DC.Date" content="2020-02-01" />
<meta name="DC.Publisher" content="American Journal of Neuroradiology" />
<meta name="DC.Rights" content="© 2020 by American Journal of Neuroradiology" />
<meta name="DC.AccessRights" content="restricted" />
<meta name="DC.Description" content="BACKGROUND AND PURPOSE: Noncontrast head CTs are routinely acquired for patients with neurologic symptoms in the emergency department setting. Anecdotally, noncontrast head CTs performed in patients with prior negative findings with the same clinical indication are of low diagnostic yield. We hypothesized that the rate of acute findings in noncontrast head CTs performed in patients with a preceding study with negative findings would be lower compared with patients being imaged for the first time.

MATERIALS AND METHODS: We retrospectively evaluated patients in the emergency department setting who underwent noncontrast head CTs at our institution during a 4-year period, recording whether the patient had undergone a prior noncontrast head CT, the clinical indication for the examination, and the examination outcome. Positive findings on examinations were defined as those that showed any intracranial abnormality that would necessitate a change in acute management, such as acute hemorrhage, hydrocephalus, herniation, or interval worsening of a prior finding.

RESULTS: During the study period, 8160 patients in the emergency department setting underwent a total of 9593 noncontrast head CTs; 88.2% (7198/8160) had a single examination, and 11.8% (962/8160) had at least 1 repeat examination. The baseline positive rate of the “nonrepeat” group was 4.3% (308/7198). The 911 patients in the “repeat” group with negative findings on a baseline/first CT had a total of 1359 repeat noncontrast head CTs during the study period. The rate of positive findings for these repeat examinations was 1.8% (25/1359), significantly lower than the 4.3% baseline rate ( P  &lt; .001). Of the repeat examinations that had positive findings, 80% (20/25) had a study indication that was discordant with that of the prior examination, compared with only 44% (593/1334) of the repeat examinations that had negative findings ( P &lt; .001).

CONCLUSIONS: In a retrospective observational study based on approximately 10,000 examinations, we found that serial noncontrast head CT examinations in patients with prior negative findings with the same study indication are less likely to have positive findings compared with first-time examinations or examinations with a new indication. This finding suggests a negative predictive value of a prior noncontrast head CT examination with negative findings with the same clinical indication.

ED
:   emergency department
NCHCT
:   noncontrast head CT" />
<meta name="DC.Contributor" content="A.L. Callen" />
<meta name="DC.Contributor" content="D.S. Chow" />
<meta name="DC.Contributor" content="Y.A. Chen" />
<meta name="DC.Contributor" content="H.R. Richelle" />
<meta name="DC.Contributor" content="J. Pao" />
<meta name="DC.Contributor" content="M. Bardis" />
<meta name="DC.Contributor" content="B.D. Weinberg" />
<meta name="DC.Contributor" content="C.P. Hess" />
<meta name="DC.Contributor" content="L.P. Sugrue" />
<meta name="article:published_time" content="2020-02-01" />
<meta name="article:section" content="Adult Brain" />
<meta name="citation_title" content="Predictive Value of Noncontrast Head CT with Negative Findings in the Emergency Department Setting" />
<meta name="citation_abstract" lang="en" content="&lt;h3&gt;BACKGROUND AND PURPOSE:&lt;/h3&gt;
&lt;p&gt;Noncontrast head CTs are routinely acquired for patients with neurologic symptoms in the emergency department setting. Anecdotally, noncontrast head CTs performed in patients with prior negative findings with the same clinical indication are of low diagnostic yield. We hypothesized that the rate of acute findings in noncontrast head CTs performed in patients with a preceding study with negative findings would be lower compared with patients being imaged for the first time.&lt;/p&gt;&lt;h3&gt;MATERIALS AND METHODS:&lt;/h3&gt;
&lt;p&gt;We retrospectively evaluated patients in the emergency department setting who underwent noncontrast head CTs at our institution during a 4-year period, recording whether the patient had undergone a prior noncontrast head CT, the clinical indication for the examination, and the examination outcome. Positive findings on examinations were defined as those that showed any intracranial abnormality that would necessitate a change in acute management, such as acute hemorrhage, hydrocephalus, herniation, or interval worsening of a prior finding.&lt;/p&gt;&lt;h3&gt;RESULTS:&lt;/h3&gt;
&lt;p&gt;During the study period, 8160 patients in the emergency department setting underwent a total of 9593 noncontrast head CTs; 88.2% (7198/8160) had a single examination, and 11.8% (962/8160) had at least 1 repeat examination. The baseline positive rate of the “nonrepeat” group was 4.3% (308/7198). The 911 patients in the “repeat” group with negative findings on a baseline/first CT had a total of 1359 repeat noncontrast head CTs during the study period. The rate of positive findings for these repeat examinations was 1.8% (25/1359), significantly lower than the 4.3% baseline rate (&lt;i&gt;P &lt;/i&gt;&amp;lt; .001). Of the repeat examinations that had positive findings, 80% (20/25) had a study indication that was discordant with that of the prior examination, compared with only 44% (593/1334) of the repeat examinations that had negative findings (&lt;i&gt;P&lt;/i&gt; &amp;lt; .001).&lt;/p&gt;&lt;h3&gt;CONCLUSIONS:&lt;/h3&gt;
&lt;p&gt;In a retrospective observational study based on approximately 10,000 examinations, we found that serial noncontrast head CT examinations in patients with prior negative findings with the same study indication are less likely to have positive findings compared with first-time examinations or examinations with a new indication. This finding suggests a negative predictive value of a prior noncontrast head CT examination with negative findings with the same clinical indication.&lt;/p&gt;" />
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<meta name="citation_publication_date" content="2020/02/01" />
<meta name="citation_mjid" content="ajnr;41/2/213" />
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<meta name="citation_author" content="A.L. Callen" />
<meta name="citation_author_institution" content="aFrom the Neuroradiology Section (A.L.C., C.P.H., L.P.S.), Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California" />
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<meta name="citation_author" content="D.S. Chow" />
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<meta name="citation_author" content="Y.A. Chen" />
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<meta name="twitter:title" content="Predictive Value of Noncontrast Head CT with Negative Findings in the Emergency Department Setting" />
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<meta name="twitter:description" content="BACKGROUND AND PURPOSE: Noncontrast head CTs are routinely acquired for patients with neurologic symptoms in the emergency department setting. Anecdotally, noncontrast head CTs performed in patients with prior negative findings with the same clinical indication are of low diagnostic yield. We hypothesized that the rate of acute findings in noncontrast head CTs performed in patients with a preceding study with negative findings would be lower compared with patients being imaged for the first time.

MATERIALS AND METHODS: We retrospectively evaluated patients in the emergency department setting who underwent noncontrast head CTs at our institution during a 4-year period, recording whether the patient had undergone a prior noncontrast head CT, the clinical indication for the examination, and the examination outcome. Positive findings on examinations were defined as those that showed any intracranial abnormality that would necessitate a change in acute management, such as acute hemorrhage, hydrocephalus, herniation, or interval worsening of a prior finding.

RESULTS: During the study period, 8160 patients in the emergency department setting underwent a total of 9593 noncontrast head CTs; 88.2% (7198/8160) had a single examination, and 11.8% (962/8160) had at least 1 repeat examination. The baseline positive rate of the “nonrepeat” group was 4.3% (308/7198). The 911 patients in the “repeat” group with negative findings on a baseline/first CT had a total of 1359 repeat noncontrast head CTs during the study period. The rate of positive findings for these repeat examinations was 1.8% (25/1359), significantly lower than the 4.3% baseline rate ( P  &lt; .001). Of the repeat examinations that had positive findings, 80% (20/25) had a study indication that was discordant with that of the prior examination, compared with only 44% (593/1334) of the repeat examinations that had negative findings ( P &lt; .001).

CONCLUSIONS: In a retrospective observational study based on approximately 10,000 examinations, we found that serial noncontrast head CT examinations in patients with prior negative findings with the same study indication are less likely to have positive findings compared with first-time examinations or examinations with a new indication. This finding suggests a negative predictive value of a prior noncontrast head CT examination with negative findings with the same clinical indication.

ED
:   emergency department
NCHCT
:   noncontrast head CT" />
<meta name="og-title" property="og:title" content="Predictive Value of Noncontrast Head CT with Negative Findings in the Emergency Department Setting" />
<meta name="og-url" property="og:url" content="http://ajnr-stage2.stage.highwire.org/content/41/2/213" />
<meta name="og-site-name" property="og:site_name" content="American Journal of Neuroradiology" />
<meta name="og-description" property="og:description" content="BACKGROUND AND PURPOSE: Noncontrast head CTs are routinely acquired for patients with neurologic symptoms in the emergency department setting. Anecdotally, noncontrast head CTs performed in patients with prior negative findings with the same clinical indication are of low diagnostic yield. We hypothesized that the rate of acute findings in noncontrast head CTs performed in patients with a preceding study with negative findings would be lower compared with patients being imaged for the first time.

MATERIALS AND METHODS: We retrospectively evaluated patients in the emergency department setting who underwent noncontrast head CTs at our institution during a 4-year period, recording whether the patient had undergone a prior noncontrast head CT, the clinical indication for the examination, and the examination outcome. Positive findings on examinations were defined as those that showed any intracranial abnormality that would necessitate a change in acute management, such as acute hemorrhage, hydrocephalus, herniation, or interval worsening of a prior finding.

RESULTS: During the study period, 8160 patients in the emergency department setting underwent a total of 9593 noncontrast head CTs; 88.2% (7198/8160) had a single examination, and 11.8% (962/8160) had at least 1 repeat examination. The baseline positive rate of the “nonrepeat” group was 4.3% (308/7198). The 911 patients in the “repeat” group with negative findings on a baseline/first CT had a total of 1359 repeat noncontrast head CTs during the study period. The rate of positive findings for these repeat examinations was 1.8% (25/1359), significantly lower than the 4.3% baseline rate ( P  &lt; .001). Of the repeat examinations that had positive findings, 80% (20/25) had a study indication that was discordant with that of the prior examination, compared with only 44% (593/1334) of the repeat examinations that had negative findings ( P &lt; .001).

CONCLUSIONS: In a retrospective observational study based on approximately 10,000 examinations, we found that serial noncontrast head CT examinations in patients with prior negative findings with the same study indication are less likely to have positive findings compared with first-time examinations or examinations with a new indication. This finding suggests a negative predictive value of a prior noncontrast head CT examination with negative findings with the same clinical indication.

ED
:   emergency department
NCHCT
:   noncontrast head CT" />
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    <div class="highwire-article-citation highwire-citation-type-highwire-article node73073--5" data-node-nid="73073" id="top-node-73073--6975691404" data-pisa="ajnr;41/2/213" data-pisa-master="ajnr;ajnr.A6408" data-apath="/ajnr/41/2/213.atom" data-hw-author-tooltip-instance="highwire_author_tooltip"><div class="highwire-cite highwire-cite-highwire-article highwire-citation-jcore-article-title-complete clearfix has-author-tooltip highwire-citation-highwire-article-top-a">
  
  
      <div class="highwire-cite-overline"><span  class="highwire-cite-metadata-article-type highwire-cite-metadata">Research Article</span><span class="separator-pipe"></span><span  class="highwire-cite-metadata-art-cat highwire-cite-metadata"><span class="wrapper">Adult Brain</span></span></div>
  
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      <h1 class="highwire-cite-title" id="page-title">Predictive Value of Noncontrast Head CT with Negative Findings in the Emergency Department Setting</h1>  
    	<div class="highwire-cite-authors"><span  class="highwire-citation-authors"><span class="highwire-citation-author first" data-delta="0">A.L. Callen</span>, <span class="highwire-citation-author" data-delta="1">D.S. Chow</span>, <span class="highwire-citation-author" data-delta="2">Y.A. Chen</span>, <span class="highwire-citation-author" data-delta="3">H.R. Richelle</span>, <span class="highwire-citation-author" data-delta="4">J. Pao</span>, <span class="highwire-citation-author" data-delta="5">M. Bardis</span>, <span class="highwire-citation-author" data-delta="6">B.D. Weinberg</span>, <span class="highwire-citation-author" data-delta="7">C.P. Hess</span> and <span class="highwire-citation-author" data-delta="8">L.P. Sugrue</span></span></div>
  
    	<div class="highwire-cite-metadata"><span  class="highwire-cite-metadata-journal highwire-cite-metadata">American Journal of Neuroradiology </span><span  class="highwire-cite-metadata-date highwire-cite-metadata">February 2020,  </span><span  class="highwire-cite-metadata-volume highwire-cite-metadata">41 </span><span  class="highwire-cite-metadata-issue highwire-cite-metadata">(2) </span><span  class="highwire-cite-metadata-pages highwire-cite-metadata">213-218; </span><span  class="highwire-cite-metadata-doi highwire-cite-metadata">DOI: https://doi.org/10.3174/ajnr.A6408 </span></div>
  
  
  
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<div id="hw-article-author-popups-top-node-73073--6975691404" style="display: none;"><div class="author-tooltip-0"><div class="author-tooltip-name">A.L. Callen </div><div class="author-tooltip-affiliation"><span class="author-tooltip-text"><div class='author-affiliation'><span class='nlm-sup'>a</span>From the Neuroradiology Section (A.L.C., C.P.H., L.P.S.), Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California</div></span></div><ul class="author-tooltip-find-more"><li class="author-tooltip-gs-link first"><a href="/lookup/google-scholar?link_type=googlescholar&amp;gs_type=author&amp;author%5B0%5D=A.L.%2BCallen%2B" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on Google Scholar</a></li><li class="author-tooltip-pubmed-link"><a href="/lookup/external-ref?access_num=Callen%20A&amp;link_type=AUTHORSEARCH" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on PubMed</a></li><li class="author-site-search-link"><a href="/search/author1%3AA.L.%2BCallen%2B" rel="nofollow" class="" data-icon-position="" data-hide-link-title="0">Search for this author on this site</a></li><li class="author-orcid-link last"><a href="https://orcid.org/0000-0003-2315-7767" target="_blank" class="" data-icon-position="" data-hide-link-title="0">ORCID record for A.L. Callen</a></li></ul></div><div class="author-tooltip-1"><div class="author-tooltip-name">D.S. Chow </div><div class="author-tooltip-affiliation"><span class="author-tooltip-text"><div class='author-affiliation'><span class='nlm-sup'>b</span>Neuroradiology Section (D.S.C., H.R.R., J.P., M.B.), Department of Radiology, University of California, Irvine, Irvine, California</div></span></div><ul class="author-tooltip-find-more"><li class="author-tooltip-gs-link first"><a href="/lookup/google-scholar?link_type=googlescholar&amp;gs_type=author&amp;author%5B0%5D=D.S.%2BChow%2B" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on Google Scholar</a></li><li class="author-tooltip-pubmed-link"><a href="/lookup/external-ref?access_num=Chow%20D&amp;link_type=AUTHORSEARCH" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on PubMed</a></li><li class="author-site-search-link"><a href="/search/author1%3AD.S.%2BChow%2B" rel="nofollow" class="" data-icon-position="" data-hide-link-title="0">Search for this author on this site</a></li><li class="author-orcid-link last"><a href="https://orcid.org/0000-0002-2359-7394" target="_blank" class="" data-icon-position="" data-hide-link-title="0">ORCID record for D.S. Chow</a></li></ul></div><div class="author-tooltip-2"><div class="author-tooltip-name">Y.A. Chen </div><div class="author-tooltip-affiliation"><span class="author-tooltip-text"><div class='author-affiliation'><span class='nlm-sup'>c</span>Trillium Health Partners (Y.A.C.), University of Toronto, Toronto, Ontario, Canada</div></span></div><ul class="author-tooltip-find-more"><li class="author-tooltip-gs-link first"><a href="/lookup/google-scholar?link_type=googlescholar&amp;gs_type=author&amp;author%5B0%5D=Y.A.%2BChen%2B" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on Google Scholar</a></li><li class="author-tooltip-pubmed-link"><a href="/lookup/external-ref?access_num=Chen%20Y&amp;link_type=AUTHORSEARCH" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on PubMed</a></li><li class="author-site-search-link"><a href="/search/author1%3AY.A.%2BChen%2B" rel="nofollow" class="" data-icon-position="" data-hide-link-title="0">Search for this author on this site</a></li><li class="author-orcid-link last"><a href="https://orcid.org/0000-0001-5315-8328" target="_blank" class="" data-icon-position="" data-hide-link-title="0">ORCID record for Y.A. Chen</a></li></ul></div><div class="author-tooltip-3"><div class="author-tooltip-name">H.R. Richelle </div><div class="author-tooltip-affiliation"><span class="author-tooltip-text"><div class='author-affiliation'><span class='nlm-sup'>b</span>Neuroradiology Section (D.S.C., H.R.R., J.P., M.B.), Department of Radiology, University of California, Irvine, Irvine, California</div></span></div><ul class="author-tooltip-find-more"><li class="author-tooltip-gs-link first"><a href="/lookup/google-scholar?link_type=googlescholar&amp;gs_type=author&amp;author%5B0%5D=H.R.%2BRichelle%2B" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on Google Scholar</a></li><li class="author-tooltip-pubmed-link"><a href="/lookup/external-ref?access_num=Richelle%20H&amp;link_type=AUTHORSEARCH" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on PubMed</a></li><li class="author-site-search-link"><a href="/search/author1%3AH.R.%2BRichelle%2B" rel="nofollow" class="" data-icon-position="" data-hide-link-title="0">Search for this author on this site</a></li><li class="author-orcid-link last"><a href="https://orcid.org/0000-0002-8671-4893" target="_blank" class="" data-icon-position="" data-hide-link-title="0">ORCID record for H.R. Richelle</a></li></ul></div><div class="author-tooltip-4"><div class="author-tooltip-name">J. Pao </div><div class="author-tooltip-affiliation"><span class="author-tooltip-text"><div class='author-affiliation'><span class='nlm-sup'>b</span>Neuroradiology Section (D.S.C., H.R.R., J.P., M.B.), Department of Radiology, University of California, Irvine, Irvine, California</div></span></div><ul class="author-tooltip-find-more"><li class="author-tooltip-gs-link first"><a href="/lookup/google-scholar?link_type=googlescholar&amp;gs_type=author&amp;author%5B0%5D=J.%2BPao%2B" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on Google Scholar</a></li><li class="author-tooltip-pubmed-link"><a href="/lookup/external-ref?access_num=Pao%20J&amp;link_type=AUTHORSEARCH" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on PubMed</a></li><li class="author-site-search-link"><a href="/search/author1%3AJ.%2BPao%2B" rel="nofollow" class="" data-icon-position="" data-hide-link-title="0">Search for this author on this site</a></li><li class="author-orcid-link last"><a href="https://orcid.org/0000-0002-9424-932X" target="_blank" class="" data-icon-position="" data-hide-link-title="0">ORCID record for J. Pao</a></li></ul></div><div class="author-tooltip-5"><div class="author-tooltip-name">M. Bardis </div><div class="author-tooltip-affiliation"><span class="author-tooltip-text"><div class='author-affiliation'><span class='nlm-sup'>b</span>Neuroradiology Section (D.S.C., H.R.R., J.P., M.B.), Department of Radiology, University of California, Irvine, Irvine, California</div></span></div><ul class="author-tooltip-find-more"><li class="author-tooltip-gs-link first"><a href="/lookup/google-scholar?link_type=googlescholar&amp;gs_type=author&amp;author%5B0%5D=M.%2BBardis%2B" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on Google Scholar</a></li><li class="author-tooltip-pubmed-link"><a href="/lookup/external-ref?access_num=Bardis%20M&amp;link_type=AUTHORSEARCH" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on PubMed</a></li><li class="author-site-search-link"><a href="/search/author1%3AM.%2BBardis%2B" rel="nofollow" class="" data-icon-position="" data-hide-link-title="0">Search for this author on this site</a></li><li class="author-orcid-link last"><a href="https://orcid.org/0000-0002-3223-2127" target="_blank" class="" data-icon-position="" data-hide-link-title="0">ORCID record for M. Bardis</a></li></ul></div><div class="author-tooltip-6"><div class="author-tooltip-name">B.D. Weinberg </div><div class="author-tooltip-affiliation"><span class="author-tooltip-text"><div class='author-affiliation'><span class='nlm-sup'>d</span>Radiology and Imaging Sciences (B.D.W.), Emory University, Atlanta, Georgia.</div></span></div><ul class="author-tooltip-find-more"><li class="author-tooltip-gs-link first"><a href="/lookup/google-scholar?link_type=googlescholar&amp;gs_type=author&amp;author%5B0%5D=B.D.%2BWeinberg%2B" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on Google Scholar</a></li><li class="author-tooltip-pubmed-link"><a href="/lookup/external-ref?access_num=Weinberg%20B&amp;link_type=AUTHORSEARCH" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on PubMed</a></li><li class="author-site-search-link"><a href="/search/author1%3AB.D.%2BWeinberg%2B" rel="nofollow" class="" data-icon-position="" data-hide-link-title="0">Search for this author on this site</a></li><li class="author-orcid-link last"><a href="https://orcid.org/0000-0002-7992-1747" target="_blank" class="" data-icon-position="" data-hide-link-title="0">ORCID record for B.D. Weinberg</a></li></ul></div><div class="author-tooltip-7"><div class="author-tooltip-name">C.P. Hess </div><div class="author-tooltip-affiliation"><span class="author-tooltip-text"><div class='author-affiliation'><span class='nlm-sup'>a</span>From the Neuroradiology Section (A.L.C., C.P.H., L.P.S.), Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California</div></span></div><ul class="author-tooltip-find-more"><li class="author-tooltip-gs-link first"><a href="/lookup/google-scholar?link_type=googlescholar&amp;gs_type=author&amp;author%5B0%5D=C.P.%2BHess%2B" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on Google Scholar</a></li><li class="author-tooltip-pubmed-link"><a href="/lookup/external-ref?access_num=Hess%20C&amp;link_type=AUTHORSEARCH" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on PubMed</a></li><li class="author-site-search-link"><a href="/search/author1%3AC.P.%2BHess%2B" rel="nofollow" class="" data-icon-position="" data-hide-link-title="0">Search for this author on this site</a></li><li class="author-orcid-link last"><a href="https://orcid.org/0000-0002-5132-5302" target="_blank" class="" data-icon-position="" data-hide-link-title="0">ORCID record for C.P. Hess</a></li></ul></div><div class="author-tooltip-8"><div class="author-tooltip-name">L.P. Sugrue </div><div class="author-tooltip-affiliation"><span class="author-tooltip-text"><div class='author-affiliation'><span class='nlm-sup'>a</span>From the Neuroradiology Section (A.L.C., C.P.H., L.P.S.), Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California</div></span></div><ul class="author-tooltip-find-more"><li class="author-tooltip-gs-link first"><a href="/lookup/google-scholar?link_type=googlescholar&amp;gs_type=author&amp;author%5B0%5D=L.P.%2BSugrue%2B" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on Google Scholar</a></li><li class="author-tooltip-pubmed-link"><a href="/lookup/external-ref?access_num=Sugrue%20L&amp;link_type=AUTHORSEARCH" target="_blank" class="" data-icon-position="" data-hide-link-title="0">Find this author on PubMed</a></li><li class="author-site-search-link"><a href="/search/author1%3AL.P.%2BSugrue%2B" rel="nofollow" class="" data-icon-position="" data-hide-link-title="0">Search for this author on this site</a></li><li class="author-orcid-link last"><a href="https://orcid.org/0000-0001-7315-4519" target="_blank" class="" data-icon-position="" data-hide-link-title="0">ORCID record for L.P. Sugrue</a></li></ul></div></div></div>  </div>

  
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    <div class="highwire-markup"><div xmlns="http://www.w3.org/1999/xhtml" data-highwire-cite-ref-tooltip-instance="highwire_reflinks_tooltip" class="content-block-markup" xmlns:xhtml="http://www.w3.org/1999/xhtml"><div class="article abstract-view "><span class="highwire-journal-article-marker-start"></span><div class="section abstract" id="abstract-1"><h2>Abstract</h2><div id="sec-1" class="subsection"><p id="p-1"><strong>BACKGROUND AND PURPOSE:</strong> Noncontrast head CTs are routinely acquired for patients with neurologic symptoms in the emergency department setting. Anecdotally, noncontrast head CTs performed in patients with prior negative findings with the same clinical indication are of low diagnostic yield. We hypothesized that the rate of acute findings in noncontrast head CTs performed in patients with a preceding study with negative findings would be lower compared with patients being imaged for the first time.</p></div><div id="sec-2" class="subsection"><p id="p-2"><strong>MATERIALS AND METHODS:</strong> We retrospectively evaluated patients in the emergency department setting who underwent noncontrast head CTs at our institution during a 4-year period, recording whether the patient had undergone a prior noncontrast head CT, the clinical indication for the examination, and the examination outcome. Positive findings on examinations were defined as those that showed any intracranial abnormality that would necessitate a change in acute management, such as acute hemorrhage, hydrocephalus, herniation, or interval worsening of a prior finding.</p></div><div id="sec-3" class="subsection"><p id="p-3"><strong>RESULTS:</strong> During the study period, 8160 patients in the emergency department setting underwent a total of 9593 noncontrast head CTs; 88.2% (7198/8160) had a single examination, and 11.8% (962/8160) had at least 1 repeat examination. The baseline positive rate of the “nonrepeat” group was 4.3% (308/7198). The 911 patients in the “repeat” group with negative findings on a baseline/first CT had a total of 1359 repeat noncontrast head CTs during the study period. The rate of positive findings for these repeat examinations was 1.8% (25/1359), significantly lower than the 4.3% baseline rate (<em>P </em>&lt; .001). Of the repeat examinations that had positive findings, 80% (20/25) had a study indication that was discordant with that of the prior examination, compared with only 44% (593/1334) of the repeat examinations that had negative findings (<em>P</em> &lt; .001).</p></div><div id="sec-4" class="subsection"><p id="p-4"><strong>CONCLUSIONS:</strong> In a retrospective observational study based on approximately 10,000 examinations, we found that serial noncontrast head CT examinations in patients with prior negative findings with the same study indication are less likely to have positive findings compared with first-time examinations or examinations with a new indication. This finding suggests a negative predictive value of a prior noncontrast head CT examination with negative findings with the same clinical indication.</p></div></div><div class="section glossary" id="glossary-1"><h2 class="">ABBREVIATIONS:</h2><dl id="def-list-1"><dt id="def-item-1">ED<span class="def-item-dt-sep"></span></dt><dd>emergency department<span class="def-item-dd-sep"></span></dd><dt id="def-item-2">NCHCT<span class="def-item-dt-sep"></span></dt><dd>noncontrast head CT</dd></dl></div><ul class="copyright-statement"><li class="fn" id="copyright-statement-1">© 2020 by American Journal of Neuroradiology</li></ul><span class="highwire-journal-article-marker-end"></span></div><span class="related-urls"></span></div><a href="http://ajnr-stage2.stage.highwire.org/content/41/2/213.full" class="hw-link hw-link-article-full-text" data-icon-position="" data-hide-link-title="0">View Full Text</a></div>  </div>

  
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      <div class="highwire-cite-title">Predictive Value of Noncontrast Head CT with Negative Findings in the Emergency Department Setting</div>  
    	<div class="highwire-cite-authors"><span  class="highwire-citation-authors"><span class="highwire-citation-author first" data-delta="0"><span class="nlm-given-names">A.L.</span> <span class="nlm-surname">Callen</span></span>, <span class="highwire-citation-author" data-delta="1"><span class="nlm-given-names">D.S.</span> <span class="nlm-surname">Chow</span></span>, <span class="highwire-citation-author" data-delta="2"><span class="nlm-given-names">Y.A.</span> <span class="nlm-surname">Chen</span></span>, <span class="highwire-citation-author" data-delta="3"><span class="nlm-given-names">H.R.</span> <span class="nlm-surname">Richelle</span></span>, <span class="highwire-citation-author" data-delta="4"><span class="nlm-given-names">J.</span> <span class="nlm-surname">Pao</span></span>, <span class="highwire-citation-author" data-delta="5"><span class="nlm-given-names">M.</span> <span class="nlm-surname">Bardis</span></span>, <span class="highwire-citation-author" data-delta="6"><span class="nlm-given-names">B.D.</span> <span class="nlm-surname">Weinberg</span></span>, <span class="highwire-citation-author" data-delta="7"><span class="nlm-given-names">C.P.</span> <span class="nlm-surname">Hess</span></span>, <span class="highwire-citation-author" data-delta="8"><span class="nlm-given-names">L.P.</span> <span class="nlm-surname">Sugrue</span></span></span></div>
  
    	<div class="highwire-cite-metadata"><span  class="highwire-cite-metadata-journal highwire-cite-metadata">American Journal of Neuroradiology </span><span  class="highwire-cite-metadata-date highwire-cite-metadata">Feb 2020, </span><span  class="highwire-cite-metadata-volume highwire-cite-metadata">41 </span><span  class="highwire-cite-metadata-issue highwire-cite-metadata">(2) </span><span  class="highwire-cite-metadata-pages highwire-cite-metadata">213-218; </span><span  class="highwire-cite-metadata-doi highwire-cite-metadata"><span class="label">DOI:</span> 10.3174/ajnr.A6408 </span></div>
  
  
  
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    	<div class="highwire-cite-authors"><span  class="highwire-citation-authors"><span class="highwire-citation-author first" data-delta="0"><span class="nlm-given-names">A.L.</span> <span class="nlm-surname">Callen</span></span>, <span class="highwire-citation-author" data-delta="1"><span class="nlm-given-names">D.S.</span> <span class="nlm-surname">Chow</span></span>, <span class="highwire-citation-author" data-delta="2"><span class="nlm-given-names">Y.A.</span> <span class="nlm-surname">Chen</span></span>, <span class="highwire-citation-author" data-delta="3"><span class="nlm-given-names">H.R.</span> <span class="nlm-surname">Richelle</span></span>, <span class="highwire-citation-author" data-delta="4"><span class="nlm-given-names">J.</span> <span class="nlm-surname">Pao</span></span>, <span class="highwire-citation-author" data-delta="5"><span class="nlm-given-names">M.</span> <span class="nlm-surname">Bardis</span></span>, <span class="highwire-citation-author" data-delta="6"><span class="nlm-given-names">B.D.</span> <span class="nlm-surname">Weinberg</span></span>, <span class="highwire-citation-author" data-delta="7"><span class="nlm-given-names">C.P.</span> <span class="nlm-surname">Hess</span></span>, <span class="highwire-citation-author" data-delta="8"><span class="nlm-given-names">L.P.</span> <span class="nlm-surname">Sugrue</span></span></span></div>
  
    	<div class="highwire-cite-metadata"><span  class="highwire-cite-metadata-journal highwire-cite-metadata">American Journal of Neuroradiology </span><span  class="highwire-cite-metadata-date highwire-cite-metadata">Feb 2020, </span><span  class="highwire-cite-metadata-volume highwire-cite-metadata">41 </span><span  class="highwire-cite-metadata-issue highwire-cite-metadata">(2) </span><span  class="highwire-cite-metadata-pages highwire-cite-metadata">213-218; </span><span  class="highwire-cite-metadata-doi highwire-cite-metadata"><span class="label">DOI:</span> 10.3174/ajnr.A6408 </span></div>
  
  
  
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