<?php
$html = 'Muita cena aqui pelo meio e com tags<br><img alt="imagem 1" src="imagem1.jpg"/><br/><img alt="imagem 2" src="imagem2.jpg"/><br/>';
foreach ($matches[1] as $key=>$value) {
echo PHP_EOL . $value;
break;
}
PD9waHAKCiRodG1sID0gJ011aXRhIGNlbmEgYXF1aSBwZWxvIG1laW8gZSBjb20gdGFnczxicj48aW1nIGFsdD0iaW1hZ2VtIDEiIHNyYz0iaW1hZ2VtMS5qcGciLz48YnIvPjxpbWcgYWx0PSJpbWFnZW0gMiIgc3JjPSJpbWFnZW0yLmpwZyIvPjxici8+JzsKCnByZWdfbWF0Y2hfYWxsKCcvPGltZyBbXj5dKnNyYz1bInxcJ10oW14ifFwnXSspL2knLCAkaHRtbCwgJG1hdGNoZXMpOwoKZm9yZWFjaCAoJG1hdGNoZXNbMV0gYXMgJGtleT0+JHZhbHVlKSB7CiAgICBlY2hvIFBIUF9FT0wgLiAkdmFsdWU7CiAgICBicmVhazsKfQ==