To perform qualitative and quantitative analysis of positron emission tomography (PET)/CT images using spontaneous ventilation (SV) and positive-pressure breath-hold (PPBH) techniques in order to demonstrate the feasibility of PPBH PET/CT to decrease respiration-induced artifacts.
5 healthy female mixed-breed dogs.
2-([18F]fluoro)-2-deoxy-D-glucose (was administered to each anesthetized dog. An SV PET/CT scan was performed from the head to the femur using 8 bed positions (3 min/bed) followed by a PPBH scan centered over the diaphragm with a single bed position (1.5 min/bed). PET image quality, the misalignment of organs between PET and CT images, and standardized uptake values (SUVs) of liver adjacent to diaphragm were compared between SV and PPBH.
Overall image quality and conspicuity of anatomic structures were superior in PPBH than in SV PET images. PPBH induced significantly less misalignment of the liver and diaphragm in all planes compared to SV. For the gall bladder, PPBH showed significantly less misalignment than SV only in the transverse plane. The maximum SUV in all of the liver areas was significantly higher with PPBH compared to SV. PPBH exhibited significantly higher mean SUV in the liver adjacent to the left diaphragmatic dome and left lateral border and higher minimum SUV only in the liver adjacent to the left diaphragmatic dome.
PPBH was demonstrated to be a feasible PET/CT protocol with higher PET image quality, less organ misalignment on fused PET/CT, and more accurate SUVs of the liver compared to SV PET/CT in healthy dogs.
OBJECTIVE To assess the feasibility of esophageal insufflation CT (EICT) for evaluation of the esophagus in dogs.
ANIMALS 7 clinically normal adult Beagles.
PROCEDURES Each dog was anesthetized twice with 1 week between anesthesia sessions. Dogs were positioned in sternal recumbency during all CT scans. During the first anesthesia session, a CT scan was performed before the esophagus was insufflated (insufflation pressure, 0 mm Hg) and unenhanced and contrast-enhanced EICT scans were performed after CO2 was insufflated into the esophageal lumen to achieve a pressure of 5 mm Hg. For the contrast-enhanced scan, each dog received iohexol (600 mg/kg, IV), and the scan was performed 30 seconds later. During the second anesthesia session, unenhanced and contrast-enhanced EICT scans were performed in the same manner except the insufflation pressure achieved was 10 mm Hg. The esophageal luminal cross-sectional area and wall thickness were measured at each of 5 segments, and mean values were compared among the 3 insufflation pressures and between unenhanced and contrast-enhanced images.
RESULTS Mean esophageal luminal cross-sectional area increased and esophageal wall thickness decreased as insufflation pressure increased. Measurements did not differ significantly between unenhanced and contrast-enhanced images. The stomach became distended with CO2 at an insufflation pressure of 10 mm Hg but not at 5 mm Hg. No adverse effects were observed.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested EICT was feasible for esophageal evaluation in dogs. Further research is necessary to determine the optimal insufflation pressure for the procedure and its diagnostic efficacy in diseased patients.
To evaluate effects of airway pressure on contrast enhancement and diameter of the pulmonary artery and determine the optimal airway pressure for pulmonary CT angiography in dogs.
8 healthy Beagles.
Thoracic CT was performed at end-expiration (0 cm H2O) and 2 positive-pressure end-inspirations (10 and 20 cm H2O). Attenuation curves of enhancement for the sinus of the pulmonary trunk artery were obtained by use of a bolus technique. Contrast medium (300 mg of I/kg) was administered IV, and CT imaging began at the time of peak enhancement. At each pressure, time to peak enhancement, ratio of blood flow from the caudal vena cava to the right side of the heart (KCdVC), and enhancement characteristics and diameter changes of the pulmonary artery were evaluated.
All dogs had a significant delay for time to peak enhancement in the sinus of the pulmonary trunk artery as airway pressure increased. The KCdVC progressively increased as airway pressure increased, and there was low contrast enhancement and increased pulmonary artery filling defects at 20 cm H2O. All pulmonary arteries had marked increases in diameter as pressure increased. Arterial distensibility in the gravity-dependent cranial lung region was greater than that in the gravity-independent caudal lung region at the 2 positive-pressure end-inspirations.
CONCLUSIONS AND CLINICAL RELEVANCE
Airway pressure affected time to peak enhancement, KCdVC, contrast enhancement, and pulmonary artery diameter. Results suggested that 10 cm H2O could be an optimal pressure for evaluation of the pulmonary artery of dogs by use of CT angiography. (Am J Vet Res 2019;80;756–763)