title: Four-dimensional ultrasound guidance during epidural anaesthesia.
abstract: BACKGROUND
  Four-dimensional (4D) ultrasound scanning (3D real-time mode) can improve the orientation of the anatomy of the area of interest and navigation by controlling the needle position. The objectives of this study were to identify the optimal technique for navigation and to assess clinically the efficacy of 4D ultrasound navigation for epidural anaesthesia at lower thoracic and lumbar levels.
  
  
  METHODS
  Single-centre case series study was performed.
  
  
  METHODS
  Sixteen patients were included. First, conventional 2D scanning was performed, followed by 4D reconstruction, and the basic tissues with high acoustic impedance (bone structures) and available acoustic windows were determined. Movement of the needle was controlled on the sagittal plane in 2D mode and at the same time in 4D mode (3D real-time mode). To improve the visibility of the needle, the 3D reconstruction was rotated during manipulation.
  
  
  RESULTS
  The 4D scanning mode provided 100 % visibility of compact bone tissues and 93 % visibility of the posterior complex. Needle visualisation strongly depended on the rotation of the reconstructed image with the sensor remaining motionless. The needle was redirected in one patient (7 %) because it was in contact with the vertebral lamina. Dilation of the epidural space during saline injection was observed in five patients (36 %). A change in the puncture level was not required any patients; no complications associated with epidural puncture were observed.
  
  
  CONCLUSIONS
  Ultrasound navigation in 4D could improve epidural anaesthesia due to the enhanced spatial orientation of the operator. The technique of "position contrast" should be used for reliable needle visualisation.
authors.affiliation: Pain Management Centre, Medical Center "Petrovskie vorota", 1-st Kolobovsky Lane, 4, 127051 Moscow, Russian Federation.
authors.forename: Alexey G
authors.initials: AG
authors.lastname: Voloshin
keywords: 3-Dimensional; Anaesthetics; Epidural; Interventional; Ultrasonography; Ultrasound