If there is evidence of equivocal disease progression on WB-MRI only, a repeat WB-MRI is undertaken between 28 and 42 days after the equivocal WB-MRI to confirm or refute the presence of progressive disease. If this confirmed disease progression, then the date of progression is defined as that of the original WB-MRI (i.e. the one performed 4-6 weeks earlier). No repeat CT scans are performed alongside the confirmatory WB-MRI.