The Government Accountability Office (GAO) has identified shortcomings in CMS’s implementation of accreditation requirements for suppliers of advanced diagnostic imaging (ADI) services under the Medicare Improvements for Patients and Providers Act of 2008 (MIPPA). For instance, the GAO found significant differences among the accrediting organizations arising from the lack of minimum national standards, rendering it difficult for CMS to monitor and assess such factors as qualifications of technologists and medical directors and the quality of clinical images. The GAO also reports that CMS’s oversight of the accreditation requirement is limited, with the initial focus on ensuring that claims were paid only to accredited suppliers. According to the GAO, CMS has not developed an oversight framework that would enable it to monitor and measure performance. The three accrediting organizations for ADI facilities approved by CMS are the American College of Radiology, the Intersociety Accreditation Commission and The Joint Commission (TJC). One area of controversy in the report involves the GAO’s criticism of TJC’s accreditation program for having less focus on imaging quality and physician qualifications than the other two accrediting organizations, assertions the TJC strongly contested. The GAO recommends that CMS: publish minimum national standards for the accreditation of ADI suppliers; develop an oversight framework for evaluating accrediting organization performance; develop more specific requirements for accrediting organization audits; and clarify guidance on immediate-jeopardy deficiencies. HHS concurred with the recommendations.