Correlation between 99Tcm-HMPAO-SPECT brain image and a history of decompression illness or extent of diving experience in commercial divers.
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.
Shields
T G
TG
Hyperbaric Research Unit, Robert Gordon University, Aberdeen.
Duff
P M
PM
Evans
S A
SA
Gemmell
H G
HG
Sharp
P F
PF
Smith
F W
FW
Staff
R T
RT
Wilcock
S E
SE
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
D015609:Organotechnetium Compounds; D010091:Oximes; D019690:Technetium Tc 99m Exametazime