title: Contrast-enhanced sonographic characterization of the vascularity of the repaired rotator cuff: utility of maximum intensity projection imaging.
abstract: OBJECTIVE
  To characterize the distribution of vascularity of the postoperative rotator cuff tendon using a maximum intensity projection technique after contrast-enhanced sonography.
  
  
  METHODS
  We retrospectively evaluated image data on 23 patients (11 male and 12 female) with intact rotator cuff repairs who had previously undergone contrast-enhanced sonography of their shoulders using lipid microspheres before and after a standardized exercise protocol. The patients were on average 3 months out from their surgery. Using offline image analysis software, a maximum intensity projection image was obtained for each patient, reflecting the regional vascular distribution within the repair and adjacent soft tissue. Subjective analysis was performed in 4 regions of interest: peribursal, articular medial, articular lateral, and suture anchor, independently by 2 musculoskeletal radiologists using a semiquantitative scale ranging from 0 to 4 for each region (0, no enhancement; 1, 1%-25% enhancement; 2, 26%-50%; 3, 51%-75%; and 4, 76%-100%). A combined vascularity score (0-8) was produced for each region and formed the basis for the subjective analysis.
  
  
  RESULTS
  Using a Mann-Whitney nonparametric test, the data showed significantly higher regional enhancement in the peribursal and suture anchor regions compared to the tendon (P < .001). Exercise resulted in a statistically significant increase in the extent of enhancement in all regions (P < .002). Inter-rater reliability analysis using a weighted κ statistic showed strong agreement (0.63-0.64) for the suture anchor site and moderate agreement for the others (peribursal, 0.35-0.39; articular medial, 0.45-0.55; and articular lateral 0.32-0.33).
  
  
  CONCLUSIONS
  The maximum intensity projection technique after contrast-enhanced sonography provides a topographic map of rotator cuff vascularity; the latter has been implicated as an important factor in promoting bone-tendon healing. Approximately 3 months after rotator cuff repair, the suture anchor and peribursal regions showed the most robust vascularity. Maximum intensity projection imaging further establishes that there is a global increase in vascular response at the repair site after exercise.
authors.affiliation: Department of Radiology and Imaging, Hospital for Special Surgery, 535 E 70th St, New York, NY 10021, USA. adlerr@hss.edu
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Adler
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Johnson
authors.forename: Stephen
authors.initials: S
authors.lastname: Fealy
authors.forename: Alex
authors.initials: A
authors.lastname: Maderazo
authors.forename: Robert A
authors.initials: RA
authors.lastname: Gallo
authors.forename: Seth C
authors.initials: SC
authors.lastname: Gamradt
authors.forename: Russell F
authors.initials: RF
authors.lastname: Warren
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D005260:Female; D005466:Fluorocarbons; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D017006:Rotator Cuff / Q000098:blood supply* / Q000000981:diagnostic imaging* / Q000601:surgery*; D018709:Statistics, Nonparametric; D053441:Suture Anchors; D013708:Tendon Injuries / Q000000981:diagnostic imaging* / Q000601:surgery*; D014159:Transducers; D014463:Ultrasonography
chemical_list: D003287:Contrast Media; D005466:Fluorocarbons; C042852:perflutren