calculated middle cerebral artery inner diameter measurement resting tone of middle cerebral artery 2012-10-23T10:09:32Z CMO:0001190 JSmith This is a calculated measurement of the relative difference in the middle cerebral artery inner diameter between a treated, fully relaxed state and a control resting state, expressed as a percentage. This calculated value is given by this equation: [(Dmax - Drest) /Dmax] x 100. VT:0002191 active resting tone of middle cerebral artery active tone of MCA clinical_measurement_ontology spontaneous resting tone of MCA tone of middle cerebral artery