[The MR signal behavior of a 4-week-old occlusive myocardial infarct in an animal experiment].
OBJECTIVE
To correlate signal behaviour in T1- and T2-weighted images after Gd-DTPA with regional histopathology in occlusive myocardial infarction (MI).


METHODS
Ligation of a diagonal branch of the LAD was performed in seven sheep. Four weeks later 0.1 mmol Gd-DTPA/kg were injected in five sheep 15 min before cardiac arrest and the sheep were slaughtered. In vitro imaging was performed at 1.5 T included T1- and T2-weighted spin echo sequences in long and short axis views. Signal intensities (SI) were determined in 36 myocardial segments per slice and compared to macro- and microscopy.


RESULTS
In all animals an antero-lateral infarct region was evident histologically. This region presented with increased T2 SI and T1 SI after Gd-DTPA. The number of segments with increased SI in T1-weighted images was higher (n = 195 segments) compared to segments with increased T2 SI (n = 122 segments). Granulation tissue could be differentiated from rarely vascularized connective tissue at a high level of significance (p < 0.001) by T1 and T2 SI analysis. Wall thickness was significantly decreased in necrotic myocardium (3.8 +/- 1.2 mm) compared to normal tissue (9.8 +/- 1.1 mm, p < 0.001).


CONCLUSIONS
In four-week-old occlusive MI the extent of necrosis can be accurately assessed by analysis of post contrast T1-weighted images. Considering regional T2 SI, granulation tissue can be differentiated from regions with predominant fibrous organisation.
Abteilung Radiologische Diagnostik, Eberhard-Karls-Universität Tübingen. stephan.miller@uni-tuebingen.de
S
S
Miller
F S
FS
Eckstein
U
U
Vogel
U
U
Hahn
A M
AM
Scheule
T
T
Nägele
F
F
Schick
C D
CD
Claussen
D000818:Animals; D003287:Contrast Media; D004195:Disease Models, Animal; D019786:Gadolinium DTPA; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000706:statistics & numerical data; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000473:pathology; D009206:Myocardium / Q000473:pathology; D009336:Necrosis; D012756:Sheep; D013997:Time Factors
D003287:Contrast Media; D019786:Gadolinium DTPA