Intercenter agreement in reading Doppler embolic signals: a multicenter international study

Background and Purpose: Different frequencies of asymptomatic Doppler embolic signals have been reported in studies. There has been concern that different criteria for identification may account for some of this variation. A previous reproducibility study between two centers found good agreement, but no studies among large numbers of centers have been performed. We performed an international reproducibility study among nine centers, each of which had published recent studies of embolic signal detection in peer-reviewed journals. Methods: Each center performed blinded analysis of a taped audio Doppler signal composed of transcranial Doppler middle cerebral artery recordings from 6 patients with symptomatic carotid artery stenosis. The exact time of any embolic signal was recorded. Six centers also measured the intensity increase of any embolic signals detected. Interobserver agreement was determined by a method based on the proportion of specific agreement. Results: Seven centers reported between 39 and 55 signals, but one center reported 142 embolic signals. The probability of agreement between observers was .678, which rose to .791 when the data from the highest reporting center were excluded. Introducing a decibel threshold resulted in a significant increase in the probability of agreement; a decibel threshold of >7 dB resulted in a probability of agreement of .902. Intensity measurements made by different centers were usually highly correlated, but this was not always the case, and 3 of the 15 correlations were not significant. The absolute values of the intensities measured varied between centers by as much as 40%. Conclusions: Although most centers report similar numbers of embolic signals, some use less specific criteria and report more events. The use of a decibel threshold improves reproducibility. However, intensity thresholds developed by one center cannot be directly transferred without validation to another center; differing methods of measurement are being used, and this results in different intensity values for the same embolic signals, even when the same equipment is used

When to perform transcranial Doppler to predict cerebral hyperperfusion after carotid endarterectomy?

SummaryCerebral hyperperfusion syndrome (CHS) after carotid endarterectomy (CEA) is a potential life-threatening disease. Identification of patients at risk for CHS commonly takes place with use of intra-operative transcranial Doppler (TCD), but is associated with both false positive and false negative results. We aimed to determine the diagnostic value for predicting CHS, by adding a TCD measurement in the early post-operative phase after CEA.We retrospectively included 72 patients who underwent CEA between January 2004 and August 2010 and in whom both intra- and post-operative TCD of the ipsilateral middle cerebral artery monitoring were performed. Twelve patients (17%) had an intra-operative mean blood flow velocity (Vmean) increase >100% and 13 patients (18%) a post-operative Vmean increase of >100%. In 5 patients (7%) CHS was diagnosed; 2 of those had an intra-operative Vmean increase of >100% and all 5 a post-operative Vmean increase >100%. This results in a positive predictive value of 17% for the intra-operative and 38% for the post-operative measurement.In conclusion, a post-operative increase of the mean velocity in the ipsilateral middle cerebral artery of >100% as measured by TCD is superior to an intra-operative velocity increase, for the identification of patients at risk for the development of CHS after CEA

CCDC 228463: Experimental Crystal Structure Determination

Related Article: J.I.van der Vlugt, M.Fioroni, J.Ackerstaff, R.W.J.M.Hanssen, A.M.Mills, A.L.Spek, A.Meetsma, H.C.L.Abbenhuis, D.Vogt|2003|Organometallics|22|5297|doi:10.1021/om030522y,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 228465: Experimental Crystal Structure Determination

Related Article: J.I.van der Vlugt, M.Fioroni, J.Ackerstaff, R.W.J.M.Hanssen, A.M.Mills, A.L.Spek, A.Meetsma, H.C.L.Abbenhuis, D.Vogt|2003|Organometallics|22|5297|doi:10.1021/om030522y,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 228464: Experimental Crystal Structure Determination

Related Article: J.I.van der Vlugt, M.Fioroni, J.Ackerstaff, R.W.J.M.Hanssen, A.M.Mills, A.L.Spek, A.Meetsma, H.C.L.Abbenhuis, D.Vogt|2003|Organometallics|22|5297|doi:10.1021/om030522y,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 228462: Experimental Crystal Structure Determination

Related Article: J.I.van der Vlugt, M.Fioroni, J.Ackerstaff, R.W.J.M.Hanssen, A.M.Mills, A.L.Spek, A.Meetsma, H.C.L.Abbenhuis, D.Vogt|2003|Organometallics|22|5297|doi:10.1021/om030522y,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.