The Government Accountability Office (GAO) has issued its second statutorily-mandated report regarding implementation of the Medicare Improvements for Patients and Providers Act of 2008 (MIPPA) accreditation requirement for Medicare suppliers that furnish the technical component of advanced diagnostic imaging (ADI) services. The first report assessed CMS's standards for ADI accreditation and the agency’s oversight of the accreditation requirement. In the second report, "Medicare Imaging Accreditation: Effect on Access to Advanced Diagnostic Imaging Is Unclear amid Other Policy Changes," the GAO concentrates on the Medicare beneficiary impact of the accreditation requirement, focusing on beneficiary use of magnetic resonance imaging, computed tomography, and nuclear medicine (including positron emission tomography services). The GAO found that the number of such ADI services provided to Medicare beneficiaries in the office setting declined at similar rates both before and after the accreditation requirement went into effect on January 1, 2012, which suggests that the overall decline was driven at least in part by factors other than accreditation. The GAO also observed that the effect of accreditation on access is unclear given the other recent policy changes implemented by CMS and private payers (e.g., payment reductions and prior authorization requirements) that also could have contributed to the decline in the number of these services. CMS officials, accrediting organization representatives, and accredited ADI suppliers that the GAO interviewed suggested that any effect of accreditation on access was likely limited.