Abstract for presentation at 38th Annual Scientific Meeting of the Australian and New Zealand Society of Nuclear Medicine 2008

Optimising the Ventilation Study in SPECT V/Q Scans

  • Dr Geofffrey Schembri, Royal North Shore Hospital, Sydney, Australia
  • Dr Benjamin Harris, Woolcock Institute of Medical Research, Department of Respiratory Med, RNSH, Australia
  • Dr Paul Roach, Royal North Shore Hospital, Sydney, Australia
  • Pr Dale Bailey, Royal North Shore Hospital, Sydney, Australia
  • Ms Elizabeth Bailey, Royal North Shore Hospital, Sydney, Australia
  • Ms Catherine Walsh, Woolcock Institute of Medical Research, Department of Respiratory Med, RNSH, Australia
  • Dr Greg King, Woolcock Institute of Medical Research, Department of Respiratory Med, RNSH, Australia

    • Objectives : SPECT V/Q imaging is superior to traditional planar scintigraphy in the diagnosis of PE. Some ventilation studies are affected by increased tracer activity in the dependent portions of the lungs producing a “rind” like effect. This can negatively impact on the scan interpretation. Our aim was to determine whether altering the method of administering Technegas or the scanning technique could reduce or eliminate this finding.

    Methods : 5 young non smoking male volunteers underwent ventilation using Technegas by two techniques: the standard technique (deep inhalation to TLC with breath holding) and a modified technique where inspiratory volume was restricted to 1 litre. Following each technique, data was acquired with the subject supine, supine with CPAP at 8 and 16mmHg and prone. Visual and quantitative assessment was made of the images -count profiles and anterior/posterior count ratios.

    Results :
    Standard technique: Increased activity was demonstrated in the dependent portion of the lungs on standard supine imaging resulting in an anterior/posterior ratio on the right of 0.5. This improved with CPAP 8, 16 and prone imaging (0.56, 0.65 and 0.64).
    Restricted inspiratory volume: The posterior rind was reduced with an anterior/posterior ratio on the right of 0.69. .This further improved with CPAP 8, 16 and prone imaging (0.73, 0.88 and 0.91). Similar results were found on the left.

    Conclusions : This study demonstrates that the SPECT ventilation image can be improved by a number of techniques with reduction of the posterior rind in particular.

    Conference Organiser - ICMS Pty Ltd