/**
 * @ORM\Column(name="image_path", type="string", length=255, nullable=true)
 */
private $imagePath;

public function getImagePath()
{
    return $this->imagePath;
}

public function setImagePath($imagePath)
{
    $this->imagePath = $imagePath;
}

{% for category in categories %}
    {% set image = category.imagePath %}
    {% if not image and category.parent %}
        {% set image = category.parent.imagePath %}
    {% endif %}

    <div class="category">
        {% if image %}
            <img src="{{ asset(image) }}" alt="{{ category.name }}">
        {% endif %}
        <div class="category-name">{{ category.name }}</div>
    </div>
{% endfor %}