title: Volumetric assessment of lesion severity with optical coherence tomography: relationship with fractional flow.
abstract: OBJECTIVE
  Frequency-domain optical coherence tomography (FD-OCT) provides a rapid tomographic scan of a coronary vessel, with an accurate reconstruction of its lumen profile. An FD-OCT-based metric that corresponds more closely with physiological significance of lesions may enable more precise guidance of interventional procedures. The aim of this feasibility study was to evaluate a new method for quantifying coronary lesion severity that estimates hyperaemic flow resistance of branched vessel segments imaged by FD-OCT.
  
  
  RESULTS
  An analytical flow model was developed that relates fractional flow reserve (FFR) to the vascular resistance ratio (VRR), a measure of blood flow resistance derived from volumetric FD-OCT lumen profiles. The VRR-FFR relationship was evaluated in 21 patients on whom both pressure measurement and FD-OCT imaging were performed in a random order during maximal hyperaemia. Lesion severity assessed by VRR showed a stronger linear correlation with FFR measurements (before model optimisation [blinded]: r=0.81; p<0.001; root mean square error [RMSE]=0.095 FFR units; after model optimisation [unblinded]: r=0.91; p<0.001; RMSE=0.066 FFR units) than quantitative coronary angiography and FD-OCT-derived measurements of minimum lumen area (r=0.67; p=0.0012) and per cent area stenosis (r=-0.61; p=0.004).
  
  
  CONCLUSIONS
  Accurate volumetric measurement of the lumen profile with FD-OCT correlates more closely with FFR than standard metrics derived from single image cross-sections. VRR shows promise as a method for evaluating lesion severity.
authors: Cardiovascular Department, Ospedali Riuniti di Bergamo, Bergamo, Italy. guagliumig@gmail.com
authors: Giulio
authors: G
authors: Guagliumi
authors: Vasile
authors: V
authors: Sirbu
authors: Christopher
authors: C
authors: Petroff
authors: Davide
authors: D
authors: Capodanno
authors: Giuseppe
authors: G
authors: Musumeci
authors: Hirosada
authors: H
authors: Yamamoto
authors: Amr
authors: A
authors: Elbasiony
authors: Christopher
authors: C
authors: Brushett
authors: Aleksandre
authors: A
authors: Matiashvili
authors: Nikoloz
authors: N
authors: Lortkipanidze
authors: Orazio
authors: O
authors: Valsecchi
authors: Hiram G
authors: HG
authors: Bezerra
authors: Joseph M
authors: JM
authors: Schmitt
mesh_terms: D000368:Aged; D003331:Coronary Vessels / Q000473:pathology*; D005260:Female; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence; D014655:Vascular Resistance