title: Cardiac CT Differentiates Left Atrial Appendage Thrombi from Circulatory Stasis in Acute Stroke Patients.
abstract: OBJECTIVE
  The left atrial appendage (LAA) is the most typical origin for a cardioembolic thrombusins' stroke etiology. Although transesophageal echocardiography (TEE) is widely used, this technique encounters difficulties in differentiating solid thrombus from circulatory stasis/spontaneous echo contrast (SEC). We assessed whether cardiac computed tomography (cCT) could more accurately detect LAA thrombi.
  
  
  METHODS
  A total of 102 patients with suspected acute cardioembolic stroke/ transient ischemic attack (TIA) without chronic atrial fibrillation underwent arterial and venous phase cCT and TEE. TEE and cCT were consensus read to define LAA thrombus, while TEE alone was used to determine SEC. The LAA/aorta Houndsfield unit (HU) ratio was measured in both phases independently and blinded to prior visual readings. The optimal LAA/aorta HU ratio cut-off value for differentiating thrombi and SEC was estimated.
  
  
  RESULTS
  TEE indicated 10 SECs and three thrombi. Consensus reading of cCT and TEE indicated that all thrombi detected in TEE were false-positive but revealed three actual thrombi missed in TEE. The LAA/aorta HU ratio correlated significantly with the presence of SEC both in arterial (p=0.019) and venous phases (p=0.024) and with the presence of thrombi in both phases (p<0.001). The best trade-off values for LAA/aorta HU ratio for the detection of thrombi was <0.245 in both phases. SEC was characterized with HU ratios of >0.245 and <0.577 in the arterial phase and>0.245 and <0.824 in the venous phase. Values of sensitivity, specificity, positive and negative predictive value and accuracy for detection of thrombi were 100% for cCT in both phases.
  
  
  CONCLUSIONS
  cCT is more accurate than TEE in the detection of LAA thrombi, especially when combined with the measurement of LAA/aorta HU ratio.
authors: Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland Unit of Radiology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland Mikko.Taina@kuh.fi.
authors: Mikko
authors: M
authors: Taina
authors: Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland Unit of Radiology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland.
authors: Ritva
authors: R
authors: Vanninen
authors: Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland Unit of Radiology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland.
authors: Petri
authors: P
authors: Sipola
authors: Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland Unit of Radiology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland.
authors: Antti
authors: A
authors: Muuronen
authors: Unit of Neurology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland NeuroCenter, Kuopio University Hospital, Kuopio, Finland.
authors: Pekka
authors: P
authors: Jäkälä
authors: Department of Clinical Radiology, Kuopio University Hospital, Kuopio, Finland Heart Center, Kuopio University Hospital, Kuopio, Finland.
authors: Marja
authors: M
authors: Hedman
mesh_terms: D000368:Aged; D020517:Atrial Appendage / Q000000981:diagnostic imaging* / Q000473:pathology; D003287:Contrast Media / Q000008:administration & dosage; D003937:Diagnosis, Differential; D017548:Echocardiography, Transesophageal; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020521:Stroke / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000473:pathology; D013927:Thrombosis / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media
keywords: Cardiac computed tomography; solid thrombus; spontaneous echo contrast; transesophageal ecocardiography