The investigator will give a clinical diagnosis at the first visit. All subjects undergo SPECT and duplex scanning, both tests will be judged blindly for the clinical diagnosis. After two years follow-up, all patients will be seen by the investigator and again a clinical diagnosis will be made (investigator is blinded for the results of the duplex and SPECT). At the end of the follow-up the sensitivity and specificity of the first clinical judgement, duplex and SPECT can be calculated. The golden standard is the clinical diagnosis at the end of the follow-up.