Quantitative and qualitative high-resolution pulmonary

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QUANTITATIVE AND QUALITATIVE HIGH-RESOLUTION PULMONARY
VENTILATION-PERFUSION IMAGING USING SIMULTANEOUS
ACQUISITION OF KRYPTON AND Tc-MAA IN HEALTHY AND RAO
AFFECTED HORSES
D J Marlin, R C Schroter1, H A Jones2, J Weekes, J C Clark3, C Deaton, D
Kingston, C Roberts and T Donovan3.
Centre for Equine Studies, Animal Health Trust, Newmarket, UK; 1Department of
Bioengineering and 2National Heart and Lung Institute, Imperial College, London,
UK; 3Wolfson Brain Imaging Centre, University of Cambridge Clinical School, UK.
Pulmonary scintigraphy has been used in horses to assess the distribution of
ventilation (V) and perfusion (Q) and V:Q matching in healthy horses and horses
with airway disease. However, as far as we are aware, V using krypton-81m
(81Krm) has previously only been reported in healthy horses and simultaneous
acquisition of
81Krm
and technetium-99m-MAA (99Tcm-MAA) has not been
reported in horses. We determined V using
81Krm
and Q using
99Tcm-MAA
and
whole lung V/Q ratios in 8 healthy horses and ponies and 8 horses and ponies
with a history and clinical diagnosis of recurrent airway obstruction (RAO), a
condition similar to human asthma, whilst in clinical remission (bronchoalveolar
lavage neutrophil count <20/l recovered fluid). Following sedation with
romifidine,
81Krm
99Tcm-MAA
(1 MBq/Kg) was injected via a catheter in the jugular vein.
gas was administered in air via a mask and non-rebreathing valve. Once
steady state had been reached with
81Krm
(20-30 seconds), radioactive counts
were acquired as 60 x 2 sec sequential time frames in a 128 x 128 pixel matrix
using a low-energy, general-purpose collimator and a 500mm circular field of
view GE gamma camera linked to a dedicated nuclear medicine computer
system (Nuclear Diagnostics Ltd). When the lung was too large to be imaged in
one field of view,
99Tcm-MAA
markers were placed on the thorax to allow caudal
and cranial images to be obtained. Dorsal views of left and right lungs were also
obtained. Mean (±SD) V/Q ratio for the whole left lateral lung field were similar for
the 2 groups; 1.01 ± 0.26 for healthy controls and 0.98 ± 0.25 for RAO affected
horses in clinical remission (P>0.05). Left lung dorsal images had a wider spread
of V/Q ratios than seen in the left lateral images. This appears to be the first
report of the range of V/Q ratios in the lungs of healthy horses and horses with
RAO in remission.
20.0
20.0
Left Lateral
mean ± sem
18.0
16.0
16.0
14.0
14.0
12.0
12.0
normal
RAO
10.0
%
%
Left Dorsal
mean ± sem
18.0
8.0
6.0
6.0
4.0
4.0
2.0
2.0
0.0
normal
10.0
8.0
RAO
0.0
0.0
0.5
1.0
1.5
V/Q Ratio
2.0
2.5
3.0
0.0
0.5
1.0
1.5
V/Q Ratio
2.0
2.5
3.0
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