Myocardial Dipyridamole-Stress Dynamic SPECT and Cardiac Adenosine-Stress MRI Unmasking the Janus Face of Coronary Microvascular Dysfunction in a 15-Year-Old Boy Incurring Recurrent Angina Pectoris, Myocardial Ischemia, and No Obstructive Coronary Artery Disease: An 11-Year Follow-Up.