High-resolution computed tomography bronchial lumen to pulmonary artery diameter ratio in anesthetized ventilated cats with normal lungs

Evaluation of the pulmonary vein ostia during the cardiac cycle using electrocardiography-gated cardiac computed tomography in cats

Several studies in humans have provided detailed descriptions of the anatomy of the pulmonary veins (PVs) and their ostia for the implementation of thoracic interventions, such as radiofrequency ablation, for patients with atrial fibrillation. These studies have shown that electrocardiography (ECG)-gated multidetector computed tomography (MDCT) can evaluate the dimensional variations in the PVs or ostium according to the cardiac cycle. However, few studies have examined the PVs or ostia using MDCT in veterinary medicine. Therefore, this study investigated the variation in the diameter of the PV ostium in cats during the cardiac cycle using ECG-gated MDCT and determined the correlation between the size of the heart or left atrium (LA) and diameter of the PV ostium. This study included six cats, including five normal animals and one cat with hypertrophic cardiomyopathy. The PVs were found to drain into the LA via three ostia, i.e., the right cranial ostium, left cranial ostium, and caudodorsal ostium. Moreover, a diametric variation was observed in all PV ostia according to the cardiac cycle phase on ECG-gated MDCT: the maximal diameter was observed at the end of ventricular systole, and the minimal diameter was observed at the end of ventricular diastole for each PV ostium. There were no significant correlations between the heart or LA size and maximal or minimal diameter of each of the three PV ostia (p > 0.05); however, the enlargement of each PV ostium at the end of ventricular systole differed significantly from that at the end of ventricular diastole. This study suggested the clinical feasibility of ECG-gated MDCT in providing more detailed anatomical information about the PVs, including the dimensional changes during the cardiac cycle in cats. Based on this study, knowledge of the variations in the PV ostium offers interesting avenues for research into the effect of PV function. Furthermore, ECG-gated MDCT could allow for greater clinical application of interventional procedures in animals with various cardiac diseases.

64-multidetector CT anatomical assessment of the feline bronchial and pulmonary vascular structures

OBJECTIVES

The aim of the study was to provide a detailed anatomical study of the feline bronchial and vascular structures by using CT angiography (CTA).

METHODS

Adult cats with no respiratory clinical signs were enrolled in a CTA protocol to provide an anatomical study of the thorax. The dimensions, number of branches and branching pattern (monopodial vs dichotomic) of both bronchial and pulmonary vascular structures were evaluated under positive inspiration apnoea. A linear generalised estimating equations analysis (Spearman's rho) was used to identify statistical correlation between tracheal diameter, age and body weight of the cats.

RESULTS

Fourteen cats met the inclusion criteria. The pulmonary arteries had larger diameters than the pulmonary veins, and the pulmonary veins had larger diameters than the bronchial structures. A higher number of segmental bronchial and pulmonary vascular branches was observed in the left caudal lung lobe than in the other lobes. The monopodial branching pattern of both bronchial and pulmonary vascular structures was predominant in all cats of our study (100%) in cranial, caudal and right middle lung lobes, while a dichotomic branching pattern of the bronchial and pulmonary vascular structures of the accessory lung lobe was seen in 13 cats (93%). Thirteen cats (93%) had three pulmonary vein ostia, and one cat (7%) also presented with an additional left intermediate pulmonary vein ostium. Variation in the number of segmental pulmonary vein branches was noted in the right caudal lung lobe. There was no statistical correlation between tracheal diameter, age and weight.

CONCLUSIONS AND RELEVANCE

Architecture of the feline bronchovascularr structures belongs to a mixed type of monopodial and dichotomic branching pattern. In cats, the pulmonary venous drainage system predominately presents three pulmonary vein ostia. Variations in the type of formation and the number of branches of the pulmonary venous drainage system were noted.

Thoracic computed tomographic interpretation for clinicians to aid in the diagnosis of dogs and cats with respiratory disease

In humans, high-resolution computed tomography (CT) is a key diagnostic modality for pulmonary disorders. Its success likely lies in excellent correlation of lung diseases with associated subgross anatomic changes, as assessed by histopathology, and because of a multidisciplinary approach between clinicians, radiologists and pathologists. Although thoracic CT studies have been performed in dogs and cats for nearly three decades, there is a lack of uniformity in both protocols for acquisition and in terminology used to describe lesions. Importantly, terms such as a bronchial, interstitial, and alveolar patterns are inappropriate descriptors for canine and feline thoracic CT imaging changes; instead, lung patterns should be classified as increased or decreased attenuation, nodular patterns, and linear patterns, with specific vocabulary to describe subtypes of lesions. In this manuscript, the authors provide an overview of basic CT principles, strategies to optimize and acquire high-quality diagnostic studies (inclusive of paired inspiratory and expiratory series, contrast and triphasic angiography) and provide a roadmap for systematic interpretation of thoracic CT images.

Ratio of the Bronchial Lumen to Pulmonary Artery Diameter in Rhesus Macaques (Macaca mulatta) without Clinical Pulmonary Disease

In human medicine, CT is widely used to detect changes in bronchial luminal diameter. The diameter of the artery that runs adjacent to the bronchus does not change dramatically along the airway path, such that this artery can be used as a reference to detect changes in the bronchial luminal diameter. The bronchoarterial ratio is increasingly used in veterinary medicine for the detection of lower airway diseases in animals. The purpose of this study was to establish the bronchoarterial ratio in rhesus macaques. We used CT to evaluate 12 rhesus macaques (Macaca mulatta) without clinical signs of pulmonary diseases and measured the bronchoarterial ratio in the right and left superior, middle, inferior and cardiac lung lobes. The overall bronchoarterial ratio (mean ± 1 SD) at all 7 locations in the 12 macaques was 0.59 ± 0.05. Moreover, there was no correlation between the BA ratio and age or sex in the study population. However, the BA ratio and weight of animals showed positive linear correlation. In this study, we established the reference range for the bronchoarterial ratio in clinically healthy rhesus macaques. This ratio is consistent among lung lobes and between animals.

High-resolution CT evaluation of bronchial lumen to vertebral body, pulmonary artery to vertebral body and bronchial lumen to pulmonary artery ratios in Dirofilaria immitis-infected cats with and without selamectin administration

Objectives The bronchial lumen to pulmonary artery (BA) ratio is utilized to evaluate pulmonary pathology on CT images. The BA ratio may be unreliable when changes are present in bronchial and pulmonary arteries concurrently. Bronchial lumen to vertebral body (BV) and pulmonary artery to vertebral body (AV) ratios have been established in normal cats and may serve as an alternative. This study aimed to evaluate the BV, AV and BA ratios in cats before and after infection with Dirofilaria immitis, with and without selamectin administration, and to characterize the distribution of disease. Methods Archived CT images were reviewed from three groups of cats: D immitis-infected untreated (n = 6); infected pretreated with selamectin (n = 6); and uninfected untreated (n = 5). The BV, AV and BA ratios were calculated for all lung lobes for baseline (D0) and day 240 (D240) postinfection. Ratios and percentage change from baseline were compared between lobes and between groups. Results BV and AV ratios were more consistent in identifying abnormalities when disease was present in bronchial and arteries concurrently than BA ratios. Infected untreated cats had significant changes in both BV and AV ratios and percentage change from baseline. Abnormal BV and AV ratios were noted in the infected selamectin group, although less widely distributed. Conclusions and relevance The BV and AV ratios more accurately identified bronchial and pulmonary artery abnormalities in D immitis-infected cats. Both bronchial and pulmonary artery changes were present in infected cats, decreasing the diagnostic application of the BA ratio. Pulmonary artery changes were more widely distributed than bronchial changes in the lung. Heartworm-infected cats receiving selamectin had bronchial and pulmonary artery changes but to a lesser extent than untreated heartworm-infected cats. The CT-derived BV and AV ratios are a useful measure to evaluate lung disease of cats.

High-resolution computed tomography evaluation of the bronchial lumen to vertebral body diameter and pulmonary artery to vertebral body diameter ratios in anesthetized ventilated normal cats

Objectives Bronchial lumen to pulmonary artery diameter (BA) ratio has been utilized to investigate pulmonary pathology on high-resolution CT images. Diseases affecting both the bronchi and pulmonary arteries render the BA ratio less useful. The purpose of the study was to establish bronchial lumen diameter to vertebral body diameter (BV) and pulmonary artery diameter to vertebral body diameter (AV) ratios in normal cats. Methods Using high-resolution CT images, 16 sets of measurements (sixth thoracic vertebral body [mid-body], each lobar bronchi and companion pulmonary artery diameter) were acquired from young adult female cats and 41 sets from pubertal female cats. Results Young adult and pubertal cat BV ratios were not statistically different from each other in any lung lobe. Significant differences between individual lung lobe BV ratios were noted on combined age group analysis. Caudal lung lobe AV ratios were significantly different between young adult and pubertal cats. All other lung lobe AV ratios were not significantly different. Caudal lung lobe AV ratios were significantly different from all other lung lobes but not from each other in both the young adult and pubertal cats. Conclusions and relevance BV ratio reference intervals determined for individual lung lobes could be applied to both young adult and pubertal cats. Separate AV ratios for individual lung lobes would be required for young adult and pubertal cats. These ratios should allow more accurate evaluation of cats with concurrent bronchial and pulmonary arterial disease.

High resolution computed tomographic evaluation of bronchial wall thickness in healthy and clinically asthmatic cats

The objective of study is to determine the thickness of bronchial walls of clinically diagnosed asthmatic cats using high resolution computed tomography (HRCT) compared to that of healthy cats. The bronchial walls and pulmonary arteries were measured in healthy 16 cats and clinically asthmatic 4 cats. The bronchial walls and pulmonary arteries were measured under general anesthesia with positive pressure inspiration using HRCT. In healthy and asthmatic cats, bronchial lumen to the artery ratio (BA ratio), the ratio of bronchial wall thickness to bronchial diameter (TD ratio) and ratio of bronchial wall thickness to pulmonary artery (TA ratio) were measured. The mean BA ratio, TD ratio and TA ratio in healthy cats were 0.86 ± 0.12, 0.18 ± 0.02 and 0.25 ± 0.05, respectively. Under the same condition, the mean BA ratio, TD ratio and TA ratio in asthmatic cats were 0.93 ± 0.21, 0.22 ± 0.24 and 0.37 ± 0.06. The TD ratio and TA ratio in asthmatic cats were significantly higher than healthy cats (P<0.001). BA ratio was not significantly different in both groups (P>0.05). The evaluation of bronchial wall thickness by HRCT could be useful for diagnosis of disease of bronchial wall thickening, such as feline asthma.

Tracheobronchial foreign bodies in cats: a retrospective study of 12 cases

Objectives The aim of the study was to evaluate age, sex, breed, clinical signs, time between onset of signs and presentation, diagnostic procedures, method of extraction, location and nature of foreign bodies (FBs) in confirmed cases of tracheobronchial FBs in cats. We hypothesised that bronchoscopy was effective in extracting tracheobronchial FBs in cats. Methods A retrospective study was performed using clinical reports from three private practices in France between May 2009 and November 2014. Cats were included if an intraluminal tracheobronchial FB had been identified and extracted (either by bronchoscopy or surgery). Results Twelve cats (six male, six female) were included. Mean age was 3.75 ± 2.5 years. Coughing was the main complaint and was present in 9/12 (75%) of the cats. Thoracic radiographs were obtained in 12/12 cats (100%) and a FB was suspected in 11/12 (92%). Bronchoscopy was performed in all of the cats and enabled FB extraction in 10/12 (83%) of them. In 2/12 cats (17%), an additional surgical approach was required. In 6/12 (50%) cats, FBs were located in the trachea, while in 6/12 (50%) cats FBs were in the bronchial tree, particularly in the right caudal bronchus (4/6; 66%). Seven of 12 (58%) FBs were vegetal in nature, 3/12 (25%) were mineral and 2/12 (17%) were undetermined. All the mineral FBs were extracted from the trachea, while the majority of the vegetal ones (5/7; 71%) were found in the bronchi. Conclusions and relevance Feline respiratory FBs can be found in the trachea and in the bronchial tree, particularly in the right caudal bronchus. Vegetal FBs tend to migrate through the bronchial tree, whereas mineral ones tend to lodge in the trachea. Bronchoscopy seems to be a highly effective procedure for the extraction of tracheobronchial FBs in cats.

Computed tomographic bronchioarterial ratio for brachycephalic dogs without pulmonary disease

The bronchoarterial (BA) ratio measured with computed tomography is widely used in human medicine to diagnose bronchial dilation or collapse. Although use of the BA ratio in veterinary medicine has been recently studied, this has not been evaluated in brachycephalic dogs predisposed to bronchial diseases including bronchial collapse. The purpose of this study was to establish BA ratios for brachycephalic dogs and compare the values with those of non-brachycephalic dogs. Twenty-three brachycephalic dogs and 15 non-brachycephalic dogs without clinical pulmonary disease were evaluated. The BA ratio of the lobar bronchi in the left and right cranial as well as the right middle, left, and right caudal lung lobes was measured. No significant difference in mean BA ratio was observed between lung lobes or the individual animals (p = 0.148). The mean BA ratio was 1.08 ± 0.10 (99% CI = 0.98~1.18) for brachycephalic dogs and 1.51 ± 0.05 (99% CI = 1.46~1.56) for the non-brachycephalic group. There was a significant difference between the mean BA ratios of the brachycephalic and non-brachycephalic groups (p = 0.00). Defining the normal limit of the BA ratio for brachycephalic breeds may be helpful for diagnosing bronchial disease in brachycephalic dogs.

Accuracy of a computed tomography bronchial wall thickness to pulmonary artery diameter ratio for assessing bronchial wall thickening in dogs

Computed tomography is increasingly being used in veterinary medicine to evaluate animals with pulmonary signs such as coughing, tachypnea, and exercise intolerance, however, a quantitative measure of bronchial wall thickening has yet to be validated in veterinary medicine. Canine chronic bronchitis is a disease that is characterized histologically by thickening of the bronchial walls. Thoracic CT images of 16 dogs with chronic bronchitis and 72 dogs presenting for conditions unrelated to cough were evaluated. A ratio comparing the bronchial wall thickness to the adjacent pulmonary artery diameter was obtained in the right and left cranial and caudal lung lobes. There was no significant difference in dogs with chronic bronchitis or unaffected dogs between the left and right hemithorax, patient weight, patient age, image slice thickness, or CT machine used. Dogs with chronic bronchitis were found to have a significantly greater ratio than unaffected dogs (P < 0.001). The ratios in the cranial lung lobes were found to be significantly greater than the caudal lung lobes in both chronic bronchitis and unaffected dogs (P < 0.001). A receiver operating characteristic curve of the ratios in the cranial lung lobes had an area under the curve of 0.912, indicating high accuracy in predicting for bronchial wall thickening. A ratio of ≥ 0.6 in the cranial lung lobes was found to have a sensitivity of 77% and specificity of 100% in predicting for the presence of chronic bronchitis, and we propose using this cut-off as supportive of bronchial wall thickening on CT.

Effect of ventilation technique and airway diameter on bronchial lumen to pulmonary artery diameter ratios in clinically normal beagle dogs

In dogs, a mean broncho-arterial ratio of 1.45 ± 0.21 has been previously defined as normal. These values were obtained in dogs under general inhalational anesthesia using a single breath-hold technique. The purpose of the study was to determine whether ventilation technique and bronchial diameter have an effect on broncho-arterial ratios. Four healthy Beagle dogs were scanned twice, each time with positive-pressure inspiration and end expiration. For each ventilation technique, broncho-arterial ratios were grouped into those obtained from small or large bronchi using the median diameter of the bronchi as the cutoff value. Mean broncho-arterial ratios obtained using positive-pressure inspiration (1.24 ± 0.23) were statistically greater than those obtained at end expiration (1.11 ± 0.20) P = 0.005. There was a strong positive correlation between bronchial diameter and broncho-arterial ratios for both ventilation techniques (positive-pressure inspiration rs = .786, P < 0.0005 and end expiration rs = .709, P < 0.0005). Mean broncho-arterial ratio for the large bronchi obtained applying positive-pressure inspiration was 1.39 cm ± 0.20 and during end expiration was 1.22 cm ± 0.20. Mean broncho-arterial ratio for the small bronchi obtained during positive-pressure inspiration was 1.08 cm ± 0.13 and during end expiration was 1.01 cm ± 0.13. There was a statistically significant difference between these groups (F = 248.60, P = 0.005). Findings indicated that reference values obtained using positive-pressure inspiration or from the larger bronchi may not be applicable to dogs scanned during end expiration or to the smaller bronchi.