Observer reliability of CT Perfusion scans

Salwa El Tawil, Grant Mair, X. Huang, Eleni Sakka, Jeb Palmer, I. Ford, L. Kalra, Keith Muir, Joanna Wardlaw

Research output: Contribution to conferencePosterpeer-review

Abstract / Description of output

Background: CT perfusion (CTP) provides potentially
valuable information to guide treatment decisions in
acute stroke. Assessment of inter-observer reliability of
CTP has, however, been limited to small, mostly single
centre studies. We performed a large, internet- based
study to assess observer reliability of CTP interpretation
in acute stroke.
Methods: We selected 24 cases from the IST-3, ATTEST
and POSH studies to illustrate various perfusion abnormalities.
Observers were presented with non-contrast CT,
maps of cerebral blood volume (CBV), cerebral blood flow
(CBF), mean transit time (MTT), delay time (DT) and thresholded
‘‘penumbra’’ maps (dichotomised into penumbra
and core), together with a short clinical vignette. A structured
questionnaire asked observers to comment on
presence of perfusion deficit, its extent compared to
ischemic changes on NCCT, and on whether CTP supported
a decision to give or withhold thrombolytic therapy.
We assessed observer agreement with Krippendorff’salpha
Results: Fifty seven observers commented on one to 24
scans (median¼10). Inter-observer agreement was substantial
for presence of an abnormality on perfusion
sequences (k alpha values CBV¼0.73, CBF¼0.64,
MTT¼0.77, DT¼0.78 and PM¼0.8). There was fair
agreement for mismatch between perfusion and NCCT
(k alpha values CBV¼0.21, CBF¼0.26, MTT¼0.39
DT¼0.38 and PM¼0.39). There was only slight agreement
on treatment decisions. (k alpha¼0.2).
Conclusions: Despite substantial agreement between
observers on presence of perfusion abnormalities, there
was less agreement on the degree of ‘‘mismatch’’, and only
slight agreement on treatment decisions.
Original languageEnglish
Number of pages2
Publication statusPublished - May 2016
EventEuropean Stroke Organisation Conference 2016 - Spain, Barcelona, United Kingdom
Duration: 10 May 201612 May 2016


ConferenceEuropean Stroke Organisation Conference 2016
Country/TerritoryUnited Kingdom


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