Abstract:
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Purpose: To assess how a new system to classify stenosis by carotid Doppler ultrasound (CDU) would impact patient management.
Methods and Materials: First, we performed a five year retrospective audit of carotid ultrasound using carotid angiography (CA) as the gold standard. Patients who had both studies within 99 days were included; each side contributed one data set termed a carotid unit (CU). Data recorded for each CU included percent angiographic stenosis as well as four CDU parameters; peak systolic and end diastolic velocities in the ICA (PSVi, EDVi) and internal to common carotid ratios of the peak systolic and end diastolic velocities (PSVr, EDVr). The correlation of each CDU parameter to percent angiographic stenosis was calculated. ROC analyses were performed using PSVi data. PSVi values to diagnose a mild (50% or less) stenosis and a severe (70% or greater) stenosis with 95% specificity (SP) were selected. The second part of our study from January 2001 to present was to evaluate the validity of this updated CDU criteria. The statistical performance of our updated criteria to diagnose mild and severe stenoses were calculated.
Results: 222 patients met the inclusion criteria for the first part, contributing 398 carotid units. Correlation co-efficients for PSVi, EDVi, PSVr, EDVr were 0.75, 0.65, 0.42 and 0.44 respectively. PSVi criteria with 95% specificity to diagnose a 50% or less and a 70% or greater stenosis were 200 cm/sec or less and 350 cm/sec or greater respectively. 48 patients have contributed 94 CU for the second part of the study. Sensitivity (SE) and SP for PSVi to diagnose a 50% or less stenosis in this group were 87% and 94% respectively. SE and SP to diagnose a 70% or greater ICA stenosis were 87% and 93% respectively. 9/48 (19%) of patients had one CU with a PSVi between 201 and 349 cm/sec.
Conclusion: High specificity for our updated PSVi criteria to diagnose a mild (50% or less) or severe (70% or greater) ICA stenosis has been maintained. Assuming patients with a mild or severe stenosis could be managed without CA and CA was only required for those patients with PSVi values falling between 201 and 349 cm/sec, 81% of patients would have been spared CA.
Kribs MD, S,
The Diagnosis of Mild and Severe Carotid Stenosis Using Peak Systolic Velocity Criteria Obtained by Receiver Operator Characteristic Analysis: Validation of a Five-Year Audit. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3108142.html
