Image auto size

Hi
I need do Image width max and image height auto size.
I try

<Frame Padding="5">
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="auto"/>
        </Grid.RowDefinitions>
        <Image Source="{Binding Title}" Aspect="AspectFill"/>
    </Grid>
</Frame>

The frame is in the ListView item.
But it is not work. How i can do it?