Computed tomographic imaging characteristics of the normal canine lacrimal glands.

BackgroundThe canine lacrimal gland (LG) and accessory lacrimal gland of the third eyelid (TEG) are responsible for production of the aqueous portion of the precorneal tear film. Immune-mediated, toxic, neoplastic, or infectious processes can affect the glands directly or can involve adjacent tissues, with secondary gland involvement. Disease affecting these glands can cause keratoconjunctivitis sicca, corneal ulcers, and loss of vision. Due to their location in the orbit, these small structures are difficult to evaluate and measure, making cross-sectional imaging an important diagnostic tool. The detailed cross-sectional imaging appearance of the LG and TEG in dogs using computed tomography (CT) has not been reported to date.ResultsForty-two dogs were imaged, and the length, width, and height were measured and the volume calculated for the LGs & TEGs. The glands were best visualized in contrast-enhanced CT images. The mean volume of the LG was 0.14 cm3 and the TEG was 0.1 cm3. The mean height, width, and length of the LG were, 9.36 mm, 4.29 mm, and 9.35 mm, respectively; the corresponding values for the TEG was 2.02 mm, 9.34 mm, and 7.90 mm. LG and TEG volume were positively correlated with body weight (p < 0.05).ConclusionsContrast-enhanced CT is a valuable tool for noninvasive assessment of canine lacrimal glands

Prediction of vascular invasion using a 7-point scale computed tomography grading system in adrenal tumors in dogs

Background: Previous studies evaluating the accuracy of computed tomography (CT) in detecting caudal vena cava (CVC) invasion by adrenal tumors (AT) used a binary system and did not evaluate for other vessels. Objective: Test a 7-point scale CT grading system for accuracy in predicting vascular invasion and for repeatability among radiologists. Build a decision tree based on CT criteria to predict tumor type. Methods: Retrospective observational cross-sectional case study. Abdominal CT studies were analyzed by 3 radiologists using a 7-point CT grading scale for vascular invasion and by 1 radiologist for CT features of AT. Animals: Dogs with AT that underwent adrenalectomy and had pre- and postcontrast CT. Results: Ninety-one dogs; 45 adrenocortical carcinomas (50%), 36 pheochromocytomas (40%), 9 adrenocortical adenomas (10%) and 1 unknown tumor. Carcinoma and pheochromocytoma differed in pre- and postcontrast attenuation, contralateral adrenal size, tumor thrombus short- and long-axis, and tumor and thrombus mineralization. A decision tree was built based on these differences. Adenoma and malignant tumors differed in contour irregularity. Probability of vascular invasion was dependent on CT grading scale, and a large equivocal zone existed between 3 and 6 scores, lowering CT accuracy to detect vascular invasion. Radiologists' agreement for detecting abnormalities (evaluated by chance-corrected weighted kappa statistics) was excellent for CVC and good to moderate for other vessels. The quality of postcontrast CT study had a negative impact on radiologists' performance and agreement. Conclusions and Clinical Importance: Features of CT may help radiologists predict AT type and provide probabilistic information on vascular invasion

In-Vivo Biodistribution and Safety of 99mTc-LLP2A-HYNIC in Canine Non-Hodgkin Lymphoma

Theranostic agents are critical for improving the diagnosis and treatment of non-Hodgkin Lymphoma (NHL). The peptidomimetic LLP2A is a novel peptide receptor radiotherapy candidate for treating NHL that expresses the activated α4β1 integrin. Tumor-bearing dogs are an excellent model of human NHL with similar clinical characteristics, behavior, and compressed clinical course. Canine in vivo imaging studies will provide valuable biodistribution and affinity information that reflects a diverse clinical population of lymphoma. This may also help to determine potential dose-limiting radiotoxicity to organs in human clinical trials. To validate this construct in a naturally occurring model of NHL, we performed in-vivo molecular targeted imaging and biodistribution in 3 normal dogs and 5 NHL bearing dogs. 99mTc-LLP2A-HYNIC-PEG and 99mTc-LLP2A-HYNIC were successfully synthesized and had very good labeling efficiency and radiochemical purity. 99mTc-LLP2A-HYNIC and 99mTc-LLP2A-HYNIC-PEG had biodistribution in keeping with their molecular size, with 99mTc-LLP2A-HYNIC-PEG remaining longer in the circulation, having higher tissue uptake, and having more activity in the liver compared to 99mTc-LLP2A-HYNIC. 99mTc-LLP2A-HYNIC was mainly eliminated through the kidneys with some residual activity. Radioactivity was reduced to near-background levels at 6 hours after injection. In NHL dogs, tumor showed moderately increased activity over background, with tumor activity in B-cell lymphoma dogs decreasing after chemotherapy. This compound is promising in the development of targeted drug-delivery radiopharmaceuticals and may contribute to translational work in people affected by non-Hodgkin lymphoma

Computed tomographic measurement of canine urine concentration.

Computed tomography (CT) is able to measure the attenuation of urine in Hounsfield units (HU) on abdominal imaging studies. This study was designed to measure the correlation of urine attenuation with urine specific gravity in urine samples of 40 dogs, providing a noninvasive measure of urine concentration. The HU of urine explained 72% of the variance in measured urine specific gravity [R2 = 0.72, F(1,38) = 95.55, P < 0.001]. This noninvasive measurement can be used to estimate urine concentration in dogs undergoing abdominal CT imaging

Table_1_Diagnosis and classification of portosystemic shunts: a machine learning retrospective case-control study.XLSX

Diagnosis of portosystemic shunts (PSS) in dogs often requires multiple diagnostic tests, and available clinicopathologic tests have limitations in sensitivity and specificity. The objective of this study was to train and validate a machine learning model (MLM) that can accurately predict the presence of a PSS utilizing routinely collected demographic data and clinicopathologic features. Dogs diagnosed with PSS or control dogs tested for PSS but had the condition ruled out (non-PSS) were identified. Dogs were included if a complete blood count and serum chemistry panel were available from PSS diagnostic testing. Dogs with a PSS were subcategorized as having a single intrahepatic PSS, a single extrahepatic PSS, or multiple extrahepatic PSS. An extreme gradient boosting (XGboost) MLM was trained with data from 70% of the cases, and MLM performance was determined on the test set, comprising the remaining 30% of the case data. Two MLMs were created. The first was designed to predict the presence of any PSS (PSS MLM), and the second to predict the PSS subcategory (PSS SubCat MLM). The trained PSS MLM had a sensitivity of 94.3% (95% CI 90.1–96.8%) and specificity of 90.5% (95% CI 85.32–94.0%) for dogs in the test set. The area under the receiver operator characteristic curve (AUC) was 0.976 (95% CI; 0.964–0.989). The mean corpuscular hemoglobin, lymphocyte count, and serum globulin concentration were most important in prediction classification. The PSS SubCat MLM had an accuracy of 85.7% in determining the subtype of PSS of dogs in the test set, with variable sensitivity and specificity depending on PSS subtype. These MLMs have a high accuracy for diagnosing PSS; however, the prediction of PSS subclassification is less accurate. The MLMs can be used as a screening tool to increase or decrease the index of suspicion for PSS before confirmatory diagnostics such as advanced imaging are pursued.</p

Assessment of 3 Bowel Preparation Protocols for Computed Tomography Pneumocolonography in Normal Dogs.

ObjectiveTo investigate the effects of 3 different bowel preparation protocols on interpretation of computed tomography (CT) pneumocolonography images.Study designExperimental crossover design.AnimalsIntact male, hound-cross, research colony dogs (n=4).MethodsAll dogs received the 3 different bowel preparation protocols for CT pneumocolonography in the same order, with a minimum of 2 weeks between protocols. For each segment of large bowel, the subjective adequacy of bowel cleansing was assessed, residual fecal and bowel volumes were calculated, and the density of fecal material in the bowel lumen was measured. Linear mixed effect models that included a random dog effect were used to evaluate mean differences in outcome measures across protocols.ResultsNo dogs experienced any clinical problems associated with the protocols or CT pneumocolonography. Bowel cleansing was considered adequate for CT pneumocolonography interpretation for all 3 protocols. There was a significant effect of protocol on residual fecal volumes and the fecal:bowel volume ratio, with the 2 protocols that included an extended fast producing the lowest total residual fecal volumes. There was a significant effect of protocol on maximum measured density of residual fecal material with the 2 protocols including iodinated contrast having the highest density.ConclusionsAll protocols were sufficient for CT pneumocolonography interpretation and contrast-tagging of residual fecal material was successful with oral iopamidol administration. An at-home bowel cleansing protocol may provide adequate bowel cleansing for CT pneumocolonography image interpretation

Long-term survival with stereotactic radiotherapy for imaging-diagnosed pituitary tumors in dogs.

Published studies on the use of stereotactic radiotherapy for dogs with pituitary tumors are limited. This retrospective observational study describes results of stereotactic radiotherapy for 45 dogs with imaging-diagnosed pituitary tumors. All dogs were treated at a single hospital during the period of December 2009-2015. The stereotactic radiotherapy was delivered in one 15 Gray (Gy) fraction or in three 8 Gy fractions. At the time of analysis, 41 dogs were deceased. Four were alive and censored from all survival analyses; one dog received 8 Gy every other day and was removed from protocol analyses. The median overall survival from first treatment was 311 days (95% confidence interval 226-410 days [range 1-2134 days]). Thirty-two dogs received 15 Gy (median overall survival 311 days; 95% confidence interval [range 221-427 days]), and 12 received 24 Gy on three consecutive days (median overall survival 245 days, 95% confidence interval [range 2-626 days]). Twenty-nine dogs had hyperadrenocorticism (median overall survival 245 days), while 16 had nonfunctional masses (median overall survival 626 days). Clinical improvement was reported in 37/45 cases. Presumptive signs of acute adverse effects within 4 months of stereotactic radiotherapy were noted in 10/45, and most had improvement spontaneously or with steroids. Late effects versus tumor progression were not discernable, but posttreatment blindness (2), hypernatremia (2), and progressive neurological signs (31) were reported. There was no statistical difference in median overall survival for different protocols. Patients with nonfunctional masses had longer median overall survival than those with hyperadrenocorticism (P&nbsp;=&nbsp;0.0003). Survival outcomes with stereotactic radiotherapy were shorter than those previously reported with definitive radiation, especially for dogs with hyperadrenocorticism