Carotid artery stenosis (NASCET and ECST) calculator

Note: This calculator estimates the degree of angiographic internal carotid artery (ICA) stenosis using the formulae of the North American Symptomatic Carotid Endarterectomy Trial (NASCET), and the European Carotid Surgery Trial (ECST). For further information scroll below the calculator.

Notes

• The calculator uses the following formulae:
  • NASCET: % ICA stenosis = (1 – [narrowest ICA diameter/diameter normal distal cervical ICA]) x 100
  • ECST: % ICA stenosis = (1 – [diameter of the most stenotic part/estimated original diameter at the site of the stenosis]) x 100
• NASCET demonstrated a benefit from surgery for those patients who have symptomatic ICA stenosis ranging between 70-99%.
  • ^{North American Symptomatic Carotid Endarterectomy Trial Collaborators, Barnett HJM, Taylor DW, Haynes RB, Sackett DL, Peerless SJ, Ferguson GG, Fox AJ, Rankin RN, Hachinski VC, Wiebers DO, Eliasziw M. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N Engl J Med. 1991 Aug 15;325(7):445-53. doi: 10.1056/NEJM199108153250701. PMID: 1852179.}
• ECST found that symptomatic patients with >80% stenosis benefit from carotid endarterectomy.
  • ^{Randomised trial of endarterectomy for recently symptomatic carotid stenosis: final results of the MRC European Carotid Surgery Trial (ECST). Lancet. 1998 May 9;351(9113):1379-87. PMID: 9593407.}

For further information and if unfamiliar with these measurements please make sure to visit the relevant Radiopaedia.org article.

Last updated: 2021-08-16