title: Correlation between 99Tcm-HMPAO-SPECT brain image and a history of decompression illness or extent of diving experience in commercial divers.
abstract: OBJECTIVE
  To explore the use of 99technetiumm-hexamethyl propylene amine oxime single photon computed tomography (HMPAO-SPECT) of the brain as a means of detecting nervous tissue damage in divers and to determine if there is any correlation between brain image and a diver's history of diving or decompression illness (DCI).
  
  
  METHODS
  28 commercial divers with a history of DCI, 26 divers with no history of DCI, and 19 non-diving controls were examined with brain HMPAO-SPECT. Results were classified by observer assessment as normal (I) or as a pattern variants (II-V). The brain images of a subgroup of these divers (n = 44) and the controls (n = 17) were further analysed with a first order texture analysis technique based on a grey level histogram.
  
  
  RESULTS
  15 of 54 commercial divers (28%) were visually assessed as having HMPAO-SPECT images outside normal limits compared with 15.8% in appropriately identified non-diver control subjects. 18% of divers with a history of DCI were classified as having a pattern different from the normal image compared with 38% with no history of DCI. No association was established between the presence of a pattern variant from the normal image and history of DCI, diving, or other previous possible neurological insult. On texture analysis of the brain images, divers had a significantly lower mean grey level (MGL) than non-divers. Divers with a history of DCI (n = 22) had a significantly lower MGL when compared with divers with no history of DCI (n = 22). Divers with > 14 years professional diving or > 100 decompression days a year had a significantly lower MGL value.
  
  
  CONCLUSIONS
  Observer assessment of HMPAO-SPECT brain images can lead to disparity in results. Texture analysis of the brain images supplies both an objective and consistent method of measurement. A significant correlation was found between a low measure of MGL and a history of DCI. There was also an indication that diving itself had an effect on texture measurement, implying that it had caused subclinical nervous tissue damage.
authors.affiliation: Hyperbaric Research Unit, Robert Gordon University, Aberdeen.
authors.forename: T G
authors.initials: TG
authors.lastname: Shields
authors.forename: P M
authors.initials: PM
authors.lastname: Duff
authors.forename: S A
authors.initials: SA
authors.lastname: Evans
authors.forename: H G
authors.initials: HG
authors.lastname: Gemmell
authors.forename: P F
authors.initials: PF
authors.lastname: Sharp
authors.forename: F W
authors.initials: FW
authors.lastname: Smith
authors.forename: R T
authors.initials: RT
authors.lastname: Staff
authors.forename: S E
authors.initials: SE
authors.lastname: Wilcock
mesh_terms: D000328:Adult; D001927:Brain Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology; D016022:Case-Control Studies; D003665:Decompression Sickness / Q000150:complications / Q000453:epidemiology* / Q000209:etiology; D004242:Diving / Q000009:adverse effects*; D006801:Humans; D009784:Occupational Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology; D015609:Organotechnetium Compounds; D010091:Oximes; D015995:Prevalence; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D015609:Organotechnetium Compounds; D010091:Oximes; D019690:Technetium Tc 99m Exametazime