title: Left ventricular thrombus attenuation characterization in cardiac computed tomography angiography.
abstract: BACKGROUND
  Because of their similar visual appearance, differentiation of left ventricular thrombotic material and myocardial wall can be difficult in contrast-enhanced coronary computed tomography (CT) angiography.
  
  
  OBJECTIVE
  We identified typical thrombi attenuation of left ventricular thrombi with the use of CT measurement.
  
  
  METHODS
  Over a time period of 6 years, we retrospectively identified 31 patients who showed a left ventricular thrombus in CT angiography datasets. Patients underwent routine contrast cardiac CT to investigate coronary artery disease. CT attenuation of each thrombus was assessed in the 4-chamber view. CT densities were also determined in the ascending aorta, left ventricle, and myocardial wall both in the mid-septal and mid-lateral segments. The mean CT attenuation of thrombi and the difference between attenuation in thrombi, left ventricular cavity, and myocardial wall were determined. The ratio of attenuation values in thrombus versus aorta and myocardium versus aorta were also determined.
  
  
  RESULTS
  Mean (±SD) CT attenuation of all left ventricular thrombi in 31 patients was 43.2 ± 15.3 HU (range, 25-80 HU). Mean CT densities of septal and lateral myocardial wall were 102.9 ± 23.1 HU (range, 63-155 HU) and 99.3 ± 28.7 HU (range, 72-191 HU), respectively, and were thus significantly higher than the CT attenuation of thrombi (P < 0.001). A threshold of 65 HU yielded a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively, to differentiate thrombus from the myocardial wall. The mean ratio between CT attenuation of thrombus and CT attenuation within the ascending aorta was 0.11 ± 0.05 (range, 0.04-0.23), which was significantly lower compared with the mean ratio between CT attenuation of the myocardial wall and the CT attenuation within the ascending aorta.
  
  
  CONCLUSIONS
  CT attenuation within left ventricular thrombi was significantly lower than myocardial attenuation in CT angiography datasets. Assessment of CT attenuation may contribute to the differentiation of thrombi.
authors.affiliation: Internal Medicine Division, University Hospital, University of São Paulo Medical School, Av. Lineu Prestes 2565, CEP: 05508-000, Butanta, Sao Paulo, Brazil. msbittencourt@bol.com.br
authors.forename: Márcio Sommer
authors.initials: MS
authors.lastname: Bittencourt
authors.forename: Stephan
authors.initials: S
authors.lastname: Achenbach
authors.forename: Mohamed
authors.initials: M
authors.lastname: Marwan
authors.forename: Martin
authors.initials: M
authors.lastname: Seltmann
authors.forename: Gerd
authors.initials: G
authors.lastname: Muschiol
authors.forename: Dieter
authors.initials: D
authors.lastname: Ropers
authors.forename: Werner G
authors.initials: WG
authors.lastname: Daniel
authors.forename: Tobias
authors.initials: T
authors.lastname: Pflederer
mesh_terms: D000368:Aged; D017023:Coronary Angiography / Q000379:methods*; D005858:Germany; D006331:Heart Diseases / Q000000981:diagnostic imaging*; D006352:Heart Ventricles / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D009206:Myocardium / Q000473:pathology; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013927:Thrombosis / Q000000981:diagnostic imaging*; D013997:Time Factors; D014057:Tomography, X-Ray Computed