title: The use of computed tomography for the estimation of DIEP flap weights in breast reconstruction: a simple mathematical formula.
abstract: BACKGROUND
  Estimation of the volume of abdominal tissue is desirable when planning autologous abdominal based breast reconstruction. However, this can be difficult clinically. The aim of this study was to develop a simple, yet reliable method of calculating the deep inferior epigastric artery perforator flap weight using the routine preoperative computed tomography angiogram (CTA) scan.
  
  
  METHODS
  Our mathematical formula is based on the shape of a DIEP flap resembling that of an isosceles triangular prism. Thus its volume can be calculated with a standard mathematical formula. Using bony landmarks three measurements were acquired from the CTA scan to calculate the flap weight. This was then compared to the actual flap weight harvested in both a retrospective feasibility and prospective study.
  
  
  RESULTS
  In the retrospective group 17 DIEP flaps in 17 patients were analyzed. Average predicted flap weight was 667 g (range 293-1254). The average actual flap weight was 657 g (range 300-1290) giving an average percentage error of 6.8% (p-value for weight difference 0.53). In the prospective group 15 DIEP flaps in 15 patients were analyzed. Average predicted flap weight was 618 g (range 320-925). The average actual flap weight was 624 g (range 356-970) giving an average percentage error of 6.38% (p-value for weight difference 0.57).
  
  
  CONCLUSIONS
  This formula is a quick, reliable and accurate way of estimating the volume of abdominal tissue using the preoperative CTA scan.
authors.affiliation: Department of Plastic, Reconstructive and Burns Surgery, Chelsea and Westminster Hospital, 369 Fulham Rd, London SW10 9NH, United Kingdom. Electronic address: t.nanidis@yahoo.co.uk.
authors.forename: Theodore G
authors.initials: TG
authors.lastname: Nanidis
authors.affiliation: Department of Plastic and Reconstructive Surgery, Imperial College Healthcare NHS Trust, Charing Cross Hospital Campus, Fulham Palace Rd, London W6 8RF, United Kingdom.
authors.forename: Hyder
authors.initials: H
authors.lastname: Ridha
authors.affiliation: Department of Plastic and Reconstructive Surgery, Imperial College Healthcare NHS Trust, Charing Cross Hospital Campus, Fulham Palace Rd, London W6 8RF, United Kingdom.
authors.forename: Navid
authors.initials: N
authors.lastname: Jallali
mesh_terms: D000328:Adult; D000368:Aged; D000792:Angiography; D019074:Epigastric Arteries / Q000000981:diagnostic imaging; D005260:Female; D057918:Fiducial Markers; D006801:Humans; D016462:Mammaplasty / Q000379:methods*; D008875:Middle Aged; D009929:Organ Size; D061525:Perforator Flap / Q000473:pathology*; D014057:Tomography, X-Ray Computed
keywords: Breast reconstruction CTA; DIEP; Volume calculation