“…Owing to the low specificity and PPV, our results show that temporal bone HR-CT is a poor indicator of coalescence. As the presence of coalescence is regarded as an indication for mastoidectomy [1,7,12,27,28], we conclude that HR-CT in isolation is not sufficient to predict whether surgery is necessary. However, because of its high sensitivity and NPV, it can be used reliably to rule out coalescence.…”