Workaround found.

I found the problem. There is some bug into Umbraco.Media. It return a value that is not an image type.
To solve I create a Macro in this manner and call it into partial view.

Macro:
@inherits umbraco.MacroEngines.DynamicNodeContext
@using umbraco.cms.businesslogic.media;
@using umbraco.BusinessLogic;

    @{
                string imageId = Convert.ToString(Model.immagineLateralePagina);
             var dynamicMediaItem = Model.MediaById(int.Parse(imageId));
            }
            

<img src="@dynamicMediaItem.crop.Find("@name", "320x613").url" alt="@imageId" title="@Model.Name"/>

and then into partiel view:

@Umbraco.RenderMacro("320x613")