How to set the value of a read-only property with generic getters and setters?

Not sure if I worded this correctly ... but I have the following code:

    public Guid ItemId
    {
        get;
    }

    public TransactionItem()
    {
        this.ItemId = Guid.Empty;
    }

Naturally I am getting a read-only issue ... which I do understand. Is there anyway to set this property value without having to do something like the below:

    Guid _itemId = Guid.Empty;
    public Guid ItemId
    {
        get
        {
            return _itemId;
        }
        set
        {
            _itemId = value;
        }
    }

or

    public Guid ItemId
    {
        get;
        internal set;
    }

Thanks in advance!