NORMAL REGIONAL DISTRIBUTION OF CEREBRAL BLOOD FLOW IN DOGS: COMPARISON BETWEEN ^99mTc‐ETHYLCYSTEINATE DIMER AND ^99mTc‐ HEXAMETHYLPROPYLENE AMINE OXIME SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY

Abstract

Functional imaging provides important insights into canine brain pathologies such as behavioral problems. Two (99m) Tc-labeled single photon emission computed tomography (SPECT) cerebral blood flow tracers-ethylcysteinate dimer (ECD) and hexamethylpropylene amine oxime (HMPAO)-are commonly used in human medicine and have been used previously in dogs but intrasubject comparison of both tracers in dogs is lacking. Therefore, this study investigated whether regional distribution differences between both tracers occur in dogs as is reported in humans. Eight beagles underwent two SPECT examinations first with (99m) Tc-ECD and followed by (99m) Tc-HMPAO. SPECT scanning was performed with a triple head gamma camera equipped with ultrahigh resolution parallel hole collimators. Images were reconstructed using filtered backprojection with a Butterworth filter. Emission data were fitted to a template permitting semiquantification using predefined regions or volumes of interest (VOIs). For each VOI, perfusion indices were calculated by normalizing the regional counts per voxel to total brain counts per voxel. The obtained perfusion indices for each region for both tracers were compared with a paired Student's T-test. Significant (P < 0.05) regional differences were seen in the subcortical region and the cerebellum. Both tracers can be used to visualize regional cerebral blood flow in dogs, however, due to the observed regional differences, they are not entirely interchangeable.

Effect of local mild hypothermia on regional cerebral blood flow in patients with acute intracerebral hemorrhage assessed by ^{99m}Tc-ECD SPECT imaging

“…Mean differences in L/NT (lesion to normal tissue) were used to estimate relative changes of rCBF, as previously reported [19,20]. This study showed that local mild hypothermia therapy could significantly increase rCBF as assessed by SPECT imaging at day 7 in ICH patients.…”

The influence of subanaesthetic ketamine on regional cerebral blood flow in healthy dogs measured with 99mTc-HMPAO SPECT

“…Regional cerebral blood flow was evaluated with SPECT using the 99m Tc-labelled tracer HMPAO (d, 1, hexamethylpropylene amine oxime, Ceretec, GE healthcare LTD, UK). This is a validated technique to study rCBF in dogs [ 40 , 41 ] . The lipophilic tracer passes the blood brain barrier and is taken up by neurons, in a manner proportionally to cerebral blood flow and neuronal function.…”

“…The lipophilic tracer passes the blood brain barrier and is taken up by neurons, in a manner proportionally to cerebral blood flow and neuronal function. In the neurons, it is transformed into a hydrophilic form and becomes trapped intracellular [ 40 ] . After dexmedetomidine premedication, a cephalic catheter was placed and the tracer was administered intravenously (30.9 MBq/kg ± 3.0 MBq).…”

Anaesthesia, not number of sessions, influences the magnitude and duration of an aHF-rTMS in dogs

“…It was hypothesized that the PI, at the stimulation site would differ significantly (α = 0.05) for each stimulation condition. [ 99m Tc]HMPAO SPECT (Single Photon Emission Computed Tomography; d, 1, hexamethylpropylene amine oxime) scans were used to semi-quantify the perfusion indices (PI) of the cortical, cerebellar, subcortical areas and the olfactory bulb [ 39 , 40 ].…”