No data are available on the echocardiographic reference intervals (RIs) for the main pulmonary artery (MPA) and right pulmonary artery (RPA) dimensions in a large sample of dogs. Therefore, we aimed to describe the echocardiographic RIs of the MPA and RPA dimensions in normal dogs. 269 healthy dogs of different breeds, age and body weight (BW) were prospectively enrolled in this multicenter, observational study. The MPA diameter, RPA maximum diameter (RPAmax), and RPA minimum diameter (RPAmin) were measured from the right parasternal short axis view. Prediction intervals (PIs) for MPA, RPAmax and RPAmin were generated using allometric scales. Reference intervals (RI) of MPA indexed to the ascending aorta (MPA/AO), and RPAmax and RPAmin indexed to the aortic annulus (RPAmax/Aod and RPAmin/Aod), were defined. A positive linear relationship between MPA, RPAmax, RPAmin and BW was evident after logarithmic transformation (R² = 0.859, R² = 0.787 and R² = 0.725, respectively; P<0.0001). According to allometric scales, the PI for the MPA normalized for BW (MPA_N) was between 5.50 and 8.07, the PI for the RPAmax normalized for BW (RPAmax_N) was between 3.23 and 5.62, while the PI for the RPAmin normalized for BW (RPAmin_N) was between 1.62 and 3.30. The median MPA/AO was 0.92 (RI, 0.78-1.01), the median RPAmax/Aod was 0.70 (RI, 0.53-0.98) and the median RPAmin/Aod was 0.40 (RI, 0.29-0.61). The reported RIs of the MPA and RPA dimensions in normal dogs could increase the diagnostic accuracy of transthoracic echocardiography in the identification of pulmonary artery enlargement in dogs.

Background: Evaluating the size of the pulmonary artery (PA) is key for the echocardiographic assessment of pulmonary hypertension (PH) in dogs. Hypothesis/Objectives: To compare the diagnostic accuracy of the main PA (MPA) and right PA (RPA) sizes for the echocardiographic detection of PH in dogs, and to evaluate differences between precapillary and postcapillary PH dogs. Animals: Four hundred four dogs; 136 controls and 268 with PH. Methods: Prospective, multicenter, observational study. The MPA, maximum and minimum RPA diameter were normalized to body weight (MPA_N, RPAmax_N, and RPAmin_N). The MPA was also indexed to the ascending aorta (MPA/AO), while the RPA size was indexed to the aortic annulus (RPAmax/Aod and RPAmin/Aod). The right pulmonary artery distensibility index (RPADi) was also calculated. The diagnostic accuracy of PA parameters for PH was assessed through the receiver operating characteristic curve analysis and area under the curve (AUC). Measurement variability was assessed trough the coefficient of variation (CV). Results: The RPADi, RPAmin_N, and RPAmin/Aod showed similar diagnostic accuracy for the detection of PH (AUC = 0.975, AUC = 0.971, and AUC = 0.953, respectively), higher than MPA/AO (AUC = 0.926), MPA_N (AUC = 0.880), RPAmax_N (AUC = 0.814), and RPAmax/Aod (AUC = 0.803; P < .05). Aside from RPAmax variables, no differences were found between precapillary and postcapillary PH. RPA size parameters showed lower CVs in comparison to MPA/AO and RPADi. Conclusions and Clinical Importance: Although MPA/AO showed an excellent sensitivity and specificity for the detection of PH, the RPAmin exhibited a higher diagnostic accuracy and less measurement variability, thus could represent a new useful parameter for the detection of PH in dogs.

The purpose of this study was to evaluate the reliability of precordial leads for the detection of right ventricular enlargement (RVE) in dogs. This was a prospective observational study. The RVE was defined by echocardiography. The amplitude (mV) of the Q, R, and S waves, the R/S ratio, and the mean electrical axis (MEA) of the QRS complex were assessed on the 12-lead ECG. The ROC curve and the Youden index yielded the best cutoffs for RVE detection. An area under the curve (AUC) > 0.7 defined suitable diagnostic accuracy. A total of 84 dogs, 27 with RVE and 57 healthy controls, were enrolled. Q wave amplitude in aVR (cutoff > 0.10 mV; AUC = 0.727), R/S ratio in V4 (cutoff < 1.15; AUC = 0.842), R/S ratio in V5 (cutoff < 1.95; AUC = 0.839) and S wave amplitude in V6 (cutoff > 0.70 mV; AUC = 0.703) showed suitable diagnostic accuracy in detecting RVE. Among dogs with RVE, only 9/27 (33%) presented a right shift of MEA. Differently, 19/27 (70%) showed at least one of the identified precordial lead criteria. Assessment of the R/S ratio in V4 and V5 and S wave amplitude in V6 increases the diagnostic accuracy of ECG in distinguishing between dogs with RVE and healthy dogs.

The gamma rays emitted by the T(D,γ)5He fusion reaction have been measured at the FNG neutron irradiation facility in ENEA-Frascati by using a large 3”x3” LaBr3 scintillator crystal. Since the gamma ray emission probability by the DT reaction is 10-5 lower with respect to the main fusion reaction channel T(D,n)4He a neutron attenuator is needed. In this paper we present the design of a neutron attenuator based on a combination of different materials. The neutron attenuator performances have been studied with a series of MCNP simulations benchmarked with an experiment performed with a 137Cs gamma ray source. The analysis of the experimental results shows a gamma component in the region of interest that is compatible with the T(D,γ)5He reaction. Although the results obtained at FNG indicate that the gamma rays emitted by the T(D,γ)5He can be measured with the present set-up, they also show that an improvement of the experimental set-up is needed. An analysis of the background induced by the scattered neutrons is provided and improvements to the neutron attenuator are proposed.