A noninvasive ultrasound technique is capable of quickly pulverizing kidney stones, an early study shows — in what researchers call a first step toward a simpler, anesthesia-free treatment for the painful problem. The study reports on the first 19 patients who’ve had kidney stones treated with the ultrasound “bursts.” So far, it’s been able to completely, or nearly completely, break up stones within 10 minutes. Much more research lies ahead, but experts not involved in the study called the early results “exciting.” If it pans out, they said, the ultrasound technique could make noninvasive treatment for kidney stones more readily available to patients. Kidney stones are common, affecting about 10% of people at some point, according to the National Kidney Foundation. Often, a stone can be passed in the urine without too much agony. In other cases — such as when a larger stone is causing a blockage or unbearable pain …