title: Automated segmental-IMT measurement in thin/thick plaque with bulb presence in carotid ultrasound from multiple scanners: Stroke risk assessment.
abstract: OBJECTIVE
  Standardization of the carotid IMT requires a reference marker in ultrasound scans. It has been shown previously that manual reference marker and manually created carotid segments are used for measuring IMT in these segments. Manual methods are tedious, time consuming, subjective, and prone to errors. Bulb edge can be considered as a reference marker for measurements of the cIMT. However, bulb edge can be difficult to locate in ultrasound scans due to: (a) low signal to noise ratio in the bulb region as compared to common carotid artery region; (b) uncertainty of bulb location in craniocaudal direction; and (c) variability in carotid bulb shape and size. This paper presents an automated system (a class of AtheroEdge™ system from AtheroPoint™, Roseville, CA, USA) for locating the bulb edge as a reference marker and further develop segmental-IMT (sIMT) which measures IMT in 10mm segments (namely: s1, s2 and s3) proximal to the bulb edge.
  
  
  METHODS
  The patented methodology uses an integrated approach which combines carotid geometry and pixel-classification paradigms. The system first finds the bulb edge and then measures the sIMT proximal to the bulb edge. The system also estimates IMT in bulb region (bIMT). The 649 image database consists of varying plaque (light, moderate to heavy), image resolutions, shapes, sizes and ethnicity.
  
  
  RESULTS
  Our results show that the IMT contributions in different carotid segments are as follows: bulb-IMT 34%, s1-IMT 29.46%, s2-IMT 11.48%, and s3-IMT 12.75%, respectively. We compare our automated results against reader's tracings demonstrating the following performance: mean lumen-intima error: 0.01235 ± 0.01224mm, mean media-adventitia error: 0.020933 ± 0.01539mm and mean IMT error: 0.01063 ± 0.0031mm. Our system's Precision of Merit is: 98.23%, coefficient of correlation between automated and Reader's IMT is: 0.998 (p-value < 0.0001). These numbers are improved compared to previous publications by Suri's group which is automated multi-resolution conventional cIMT.
  
  
  CONCLUSIONS
  Our fully automated bulb detection system reports 92.67% precision against ideal bulb edge locations as marked by the reader in the bulb transition zone.
authors.affiliation: Division of Cardiovascular Medicine, Toho University Ohashi Medical Center, 2-17-6 Ohashi Meguro-ku, Tokyo, Japan.
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Ikeda
authors.affiliation: Point of Care Devices, Global Biomedical Technologies, Inc., Roseville, CA, USA.
authors.forename: Nilanjan
authors.initials: N
authors.lastname: Dey
authors.affiliation: Cardiovascular Medicine, University of Virginia, VA, USA.
authors.forename: Aditya
authors.initials: A
authors.lastname: Sharma
authors.affiliation: Department of Radiology, Brain and Mind Research Institute, Weill Cornell Medical College, NY, USA.
authors.forename: Ajay
authors.initials: A
authors.lastname: Gupta
authors.affiliation: Point of Care Devices, Global Biomedical Technologies, Inc., Roseville, CA, USA.
authors.forename: Soumyo
authors.initials: S
authors.lastname: Bose
authors.affiliation: Point of Care Devices, Global Biomedical Technologies, Inc., Roseville, CA, USA.
authors.forename: Suvojit
authors.initials: S
authors.lastname: Acharjee
authors.affiliation: CorVasc Vascular Laboratory, 8433 Harcourt Rd #100, Indianapolis, IN, USA.
authors.forename: Shoaib
authors.initials: S
authors.lastname: Shafique
authors.affiliation: IMIM - Hospital del Mar, PasseigMarítim 25-29, Barcelona, Spain.
authors.forename: Elisa
authors.initials: E
authors.lastname: Cuadrado-Godia
authors.affiliation: Division of Cardiovascular Medicine, Centre for Global Health and Medicine (NCGM), 1-21-1 Toyama Shinjuku-ku, Tokyo, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Araki
authors.affiliation: Azienda Ospedaliero Universitaria (A.O.U.) di Cagliari - Polo di Monserrato, Università di Cagliari, s.s. 554 Monserrato, Cagliari 09045, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Saba
authors.affiliation: UC Davis Vascular Center, University of California, Davis, CA, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Laird
authors.affiliation: Vascular Screening and Diagnostic Centre, London, and Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus.
authors.forename: Andrew
authors.initials: A
authors.lastname: Nicolaides
authors.affiliation: Point of Care Devices, Global Biomedical Technologies, Inc., Roseville, CA, USA; Diagnostic and Monitoring Division, AtheroPoint™ LLC, Roseville, CA, USA; Electrical Engineering Department (Aff.), Idaho State University, ID, USA. Electronic address: jasjit.suri@atheropoint.com.
authors.forename: Jasjit S
authors.initials: JS
authors.lastname: Suri
mesh_terms: D001331:Automation; D059168:Carotid Intima-Media Thickness; D003628:Database Management Systems; D006801:Humans; D015203:Reproducibility of Results; D018570:Risk Assessment; D020521:Stroke / Q000453:epidemiology*
keywords: Carotid ultrasound; Heavy plaque; Segmental-IMT; Stroke risk assessment; bIMT; cIMT