Her insurer refused to pay for another scan, but the doctor said he was sure she had torn cartilage that stabilizes the knee and suggested an operation to fix it. After the surgery, Ms. Kislevitz, 57, of Ridgewood, N.J., received a surprise: the cartilage had not been torn after all.
She had a long rehabilitation. And her insurer paid for the operation. But her knee is no better.
More than 95 million high-tech scans are done each year, and medical imaging, including CT, M.R.I. and PET scans, has ballooned into a $100-billion-a-year industry in the United States, with Medicare paying for $14 billion of that. But recent studies show that as many as 20 percent to 50 percent of the procedures should never have been done because their results did not help diagnose ailments or treat patients.
"The system is just totally, totally broken," said Dr. Vijay Rao, the chairwoman of the radiology department at Thomas Jefferson University Hospital, in Philadelphia.