Encoding problem with caption in Imagemagick on php - php

Question

I'm adding some heading in Russian on the image using newPseudoImage and CAPTION.
Heading can have some entities like — etc, so I clean it with html_entity_decode.
In some cases it works well, but in some cases text after decoded entity goes in wrong encoding, like that:
look at second line - there is the problem
Please, help me to find the solution.
If I use annotateImage - everything is nice.
If I use newPseudoImage and LABEL - everything is nice.
The problem appears only with newPseudoImage and CAPTION (but I have to CAPTION, cause I need to scale my headings depending on their length).
At the same time I have to use these entities in headings (i.e. to avoid wrapping of the dash to the next line).
Some headings shows nice:
'Путешествие в Карелию' - is fine, but 'Нуорунен в Карелии' - shows with error.
My code:
$postTitle = 'Нуорунен в Карелии';
$postTitle = html_entity_decode($postTitle);
$mainImage = new Imagick('source.jpg');
$title = new Imagick();
$colorize = new Imagick();
$mainImage->setImageCompressionQuality(85);
$title->setBackgroundColor('transparent');
$title->setFont('/fonts/roboto-slab_semibold.ttf');
$title->setGravity(imagick::GRAVITY_CENTER);
$title->newPseudoImage( 780, 480, "CAPTION:" . $postTitle );
$colorize->newImage(1, 1, new ImagickPixel('#f8bb00'));
$title->clutImage($colorize);
$colorize->destroy();
$mainImage->compositeImage($title, imagick::COMPOSITE_DEFAULT, 210, 110);
$mainImage->writeImage('image.jpg');