Evaluation of quantified contrast-enhanced color and power Doppler ultrasonography for the assessment of vascularity and perfusion of naturally occurring tumors in dogs

OBJECTIVE: To investigate subjective and computerized methods of evaluation of color Doppler (CD) and power Doppler (PD) ultrasonographic images (obtained before and after administration of contrast medium) for quantitative assessment of vascularity and perfusion of various naturally occurring tumors in dogs. SAMPLE POPULATION: 34 tumors in 34 dogs. PROCEDURE: Tumors in dogs were examined via CD and PD ultrasonography before and after i.v. injection of a microbubble contrast agent (pre- and postcontrast examinations, respectively). Images were digitized for subjective assessment of vessel density and vascular pattern and computer-aided assessment of parameters of vascularity (fractional area [FA]) and perfusion (color-weighted FA [CWFA] and mean color-weighted FA [CWFA] and mean color level). RESULTS: With both analysis methods, more vessels were identified in precontrast PD ultrasonographic images than in precontrast CD ultrasonographic images. Moreover, compared with values for precontrast PD ultrasonography, FA, CWFA, and mean color level were higher for postcontrast PD ultrasonography. In postcontrast images, there was a significant association between vessel densities determined through subjective and computerized assessments. Although sample size was small, vascularity of squamous cell carcinomas was significantly greater than that of other tumor types. Ten of the 19 softer than issue that sarcomas had low vessel density with minor contrast enhancement. With increasing gross tumor volume, FA and CWFA decreased for all Doppler ultrasonographic methods. CONCLUSIONS AND CLINICAL RELEVANCE: Higher values of the ultrasonographic parameters representing vascularity and perfusion of tumors in dogs were determined via PD ultrasonography after administration of contrast medium than via PD or CD ultrasonography without administration of contrast medium.     

Evaluation of serum feline trypsin-like immunoreactivity for the diagnosis of pancreatitis in cats

OBJECTIVE: To evaluate serum feline trypsin-like immunoreactivity (fTLI) concentration and results of abdominal ultrasonography, CBC, and serum biochemical analyses for diagnosis of pancreatitis in cats. DESIGN: Prospective study. ANIMALS: 28 cats with clinical signs compatible with pancreatitis. PROCEDURE: Serum fTLI concentrations were determined, and abdominal ultrasonography, CBC, and serum biochemical analyses were performed prior to histologic evaluation of pancreatic, hepatic, and intestinal specimens. On the basis of histologic results, cats were categorized as having a normal pancreas (n = 10), pancreatic fibrosis with ongoing inflammation (9), pancreatic fibrosis without inflammation (4), and acute necrotizing pancreatitis (5). Serum fTLI concentrations and results of CBC, serum biochemical analyses, and histologic evaluation of hepatic and intestinal specimens were compared among groups. RESULTS: Significant differences in serum fTLI concentrations or any hematologic or biochemical variable were not detected among the 4 groups of cats. Median serum fTLI concentrations were 51 micrograms/L (range, 18 to 200 micrograms/L) in cats with a normal pancreas, 32 micrograms/L (range, 12 to > 200 micrograms/L) in cats with pancreatic fibrosis and ongoing inflammation, 124 micrograms/L (range, 36 to > 200 micrograms/L) in cats with pancreatic fibrosis without ongoing inflammation, and 30 micrograms/L (range, 24 to 84 micrograms/L) in cats with acute necrotizing pancreatitis. We detected a high prevalence of concurrent hepatic and intestinal tract disease in cats with pancreatitis. CONCLUSIONS AND CLINICAL RELEVANCE: In cats with clinical signs of pancreatitis, serum fTLI concentration is poorly associated with histopathologic diagnosis.     

Comparisons between cats with normal and increased fPLI concentrations in cats diagnosed with inflammatory bowel disease

Objectives : The aim of this study was to compare age, serum albumin and cobalamin concentrations, serum alanine amino transferase and alkaline phosphatase activities, feline inflammatory bowel disease clinical disease activity index, pancreatic ultrasound findings, intestinal histopathology scores, outcome, treatment and clinical response between cats diagnosed with inflammatory bowel disease with normal or increased serum feline pancreatic lipase immunoreactivity concentrations. Methods : Medical records for 23 cats diagnosed with inflammatory bowel disease and with serum feline pancreatic lipase immunoreactivity concentrations available were reviewed. Three groups were compared; cats with serum feline pancreatic lipase immunoreactivity concentrations 2·0 to 6·8 µg/l (group A), 6·9 to 11·9 µg/l (group B) and ≥12·0 µg/l (group C). Results : Sixteen of the 23 cats had increased serum feline pancreatic lipase immunoreactivity concentrations; 9 cats in group B and 7 cats in group C. The remaining seven cats were in group A. Cats with serum feline pancreatic lipase immunoreactivity concentrations ≥12·0 µg/l had significantly lower median serum albumin and cobalamin concentrations. No significant differences were identified between the three groups for age, serum alanine amino transferase and alkaline phosphatase activities, feline inflammatory bowel disease clinical disease activity index, pancreatic ultrasound findings, intestinal histopathology scores, clinical outcome, treatment or clinical response. Clinical Significance : Hypoalbuminaemia and hypocobalaminaemia were more frequently observed in cats with serum feline pancreatic lipase immunoreactivity concentrations ≥12·0 µg/l.     

Computed Tomographic Angiography of the Pancreas in Cats with Chronic Diabetes Mellitus Compared to Normal Cats

Background

Diabetes mellitus (DM) is a common endocrinopathy in cats. No known diagnostic test or patient characteristic at the time of diagnosis can predict likely disease course, unlike in people in whom computed tomographic angiography (CTA) is used. No published data exist regarding the CTA appearance of the pancreas in cats with DM, and thus, it is unknown what if any CTA variables should be further assessed for associations with pancreatic endocrine function.

Hypothesis/Objectives

A significant difference in pancreatic attenuation, volume, and size will be identified between normal cats and those with chronic DM on CTA.

Animals

Ten healthy control cats and 15 cats with naturally occurring DM present for >12 months.

Methods

Prospective cross‐sectional study comparing pancreatic attenuation, enhancement pattern, size, volume, pancreatic volume‐to‐body weight ratio (V:BW), pancreatic arterial: portal phase ratio (A:P), time‐to‐arterial enhancement, and time‐to‐peak portal enhancement on CTA between sedated healthy control cats and those with chronic DM.

Results

The pancreas in cats with chronic DM was significantly larger, had higher volume, higher V:BW, and shorter time‐to‐peak portal enhancement on CTA when compared to normal cats.

Conclusions and Clinical Importance

Peak portal enhancement time, pancreatic size, pancreatic volume, and V:BW can be used to differentiate normal sedated cats from those with chronic DM by CTA. These variables warrant further investigation to identify possible associations with endocrine function.     

Duplex Doppler Estimation of Pourcelot Resistive Index in Arcuate Arteries of Sedated Normal Cats

Renal failure is an important cause of morbidity and mortality in feline patients. In human patients, intrarenal blood flow values obtained with duplex Doppler ultrasonography have been used to aid in the diagnosis and prognosis of renal failure. The purpose of this report is to present values for resistance to intrarenal blood flow in normal cats, derived by duplex Doppler ultrasonography. Ten mature clinically healthy conditioned domestic shorthaired cats were screened for normal renal anatomy and function by CBC, serum biochemical profile, urinalysis, urine protein/creatinine ratio, endogenous creatinine clearance, and renal B-mode ultrasonography; and for normal systemic blood pressure with Doppler pressure cuff measurement. Subsequently, the cats were sedated with ketamine hydrochloride, and values for mean intrarenal (arcuate artery) resistance to blood flow were determined by duplex Doppler ultrasonography, and expressed as the Pourcelot resistive index, a ratio of systolic to diastolic flow commonly used in duplex Doppler sonography in human patients. After duplex Doppler sonographic examination, histological normalcy of the kidneys was verified by evaluation of ultrasound-guided percutaneous renal biopsy. Based on the obtained resistive indices, 95% confidence intervals for normal values were calculated as follows: left kidney, 0.52 to 0.60; right kidney, 0.55 to 0.63. No statistically significant difference was noted between the values obtained for the right versus the left kidney. J Vet Intern Med 1996;10:28–33. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

Triple phase computed tomography of the pancreas in healthy cats

While the availability and use of computed tomography (CT) continues to grow, no study has described the size and multiphase CT appearance of the normal feline pancreas. This information is important to not only allow more accurate identification and differentiation of disease, but it may also be useful in assessing pancreatic function. In this prospective analytical study, we described a triple phase CT protocol of the pancreas for use in sedated cats and the attenuation, enhancement pattern, size, and volume of the pancreas for a group of healthy cats. Fifteen healthy cats were enrolled in the study and a standardized protocol for acquiring arterial, portal, and delayed phase CT images of the pancreas was developed and described. The pancreas was hypo to isoattenuating to both the liver and spleen in all phases in the majority of cats with a homogenous enhancement pattern noted in all 15. Mean pancreatic attenuation was 48, 79, 166, and 126 Hounsfield units (HU) respectively on precontrast, arterial, portal, and delayed phase images. In addition, mean height, length, and width of the left lobe of the pancreas were larger than the right lobe in all 15 cats. There were no associations between volume and volume: body weight ratio with age (P = 0.6518, P = 0.6968) or sex (P = 0.7013, P = 0.2043). This baseline information may be beneficial for use in future studies characterizing pancreatic disease in cats as well as future research studies evaluating pancreatic endocrine function.     

ENDOSCOPIC ULTRASONOGRAPHY OF THE PANCREAS IN THE DOG

Endoscopic ultrasonography was done in 12 normal adult dogs to investigate its efficacy in visualization of the pancreas. The endoscopic ultrasonographic device used in the present study had a curved-array ultrasound transducer mounted in front of the objective lens. The tip of the ultrasonic endoscope was inserted into the stomach, and all examinations of the pancreas were performed from within the stomach. Endoscopic ultrasonography provided good images of most parts of the pancreas except for the ends of each lobe. Useful information about the pancreatic parenchyma, including pancreatic lobular structure, pancreatic duct, and vessels of the pancreas was obtained by endoscopic ultrasonography. Blood flow within vessels was detected using color Doppler and pulsed-wave Doppler examination. These results suggest that endoscopic ultrasonography is available as an effective diagnostic modality in small animal practice.     

B‐mode and power Doppler ultrasonography of the equine suspensory ligament branches: A descriptive study on 13 horses

Ultrasonography is routinely used to achieve the diagnosis of equine suspensory ligament desmopathy. In human medicine, power Doppler ultrasonography has also been found to be useful for the diagnosis of tendon/ligament injuries. The aim of this prospective, pilot study was to assess the presence or absence of power Doppler signal in suspensory ligament branches and compare B‐mode findings with power Doppler findings in suspensory ligament branches of lame and non‐lame limbs. Thirteen horses were used (eight lame horses, with lameness related to pain in the suspensory ligament branches, and five non‐lame horses). Ten lame limbs and 24 sound limbs were assessed by B‐mode and power Doppler ultrasonography. The severity of power Doppler signal was scored by two independent readers. The B‐mode ultrasonographic examination revealed abnormalities in branches of lame limbs and in branches of sound limbs. Suspensory ligament branches that were considered normal in B‐mode showed no power Doppler signal. However, power Doppler signal was detected in suspensory ligament branches that were abnormal in B‐mode, both in lame and sound limbs. Power Doppler scores were subjectively higher in suspensory ligament branches of lame limbs and in branches with more severe B‐mode changes. Findings supported the use of power Doppler as an adjunctive diagnostic test for lame horses with suspected suspensory desmopathy.     

Feline exocrine pancreatic disorders.

Despite the uncommon clinical diagnosis, cats frequently suffer from disorders of the exocrine pancreas. Pancreatitis is the most common feline exocrine pancreatic disorder. Pancreatitis can be acute or chronic and mild or severe. The etiology of most cases of feline pancreatitis is idiopathic. Some cases have been associated with severe abdominal trauma, infectious diseases, cholangiohepatitis, and organophosphate and other drug intoxication. The clinical presentation of cats with pancreatitis is nonspecific. Vomiting and signs of abdominal pain, which are the clinical signs most commonly observed in humans and dogs with pancreatitis, are only uncommonly observed in cats with pancreatitis. Routine laboratory findings are also nonspecific. Abdominal ultrasonography is a valuable diagnostic tool in feline patients with pancreatitis. Serum activities of lipase and amylase are rarely increased in cats with pancreatitis; however, these cats often have elevated serum fTLI concentrations. The goals of management are removal of the inciting cause, provision of supportive and symptomatic therapy, and careful monitoring for and aggressive treatment of systemic complications. Exocrine pancreatic insufficiency is a syndrome caused by insufficient synthesis of pancreatic digestive enzymes by the exocrine portion of the pancrease. The clinical signs most commonly reported are weight loss, loose and voluminous stools, and greasy soiling of the hair coat. Serum fTLI is subnormal in affected cats. Treatment of cats with EPI consists of enzyme supplementation with powdered pancreatic extracts or raw beef pancreas. Many cats with EPI have concurrent small intestinal disease. Most cats with EPI also have severely decreased serum cobalamin concentrations and may require parenteral cobalamin supplementation. Pancreatic adenocarcinoma is the most common neoplastic condition of the exocrine pancreas in the cat. At the time of diagnosis, the tumor has already metastasized in most cases, and the prognosis is poor. Pancreatic pseudocyst, pancreatic abscess, pancreatic parasites, pancreatic bladder, and nodular hyperplasia are other exocrine pancreatic disorders, that are less commonly seen in cats.     

Feline pancreatic ducts are consistently identified on CT and more likely to be dilated in the body of pancreas in cats with elevated feline pancreatic lipase immunoreactivity

Feline pancreatitis is a challenge to diagnose and no previously published study has described the CT characteristics of the pancreatic duct (PD) in cats. The current prospective analytical study was performed to identify and describe the CT characteristics of the PD in normal cats and to compare that to those cats with an elevated feline pancreatic lipase immunoreactivity (fPLI). Contrast‐enhanced CT was performed in 16 normal cats and 13 cats with an elevated fPLI. Two ACVR‐certified radiologists blinded to the fPLI status assessed whether or not the PD could be identified, contrast phase during which the PD was most conspicuous, and PD shape in the body, right and left lobes. A second‐year radiology resident blinded to the fPLI status measured maximum PD diameter and PD:parenchyma. The PD was identified in 84 of 87 pancreatic segments, which was most conspicuous in the portal phase in 28 of 29 cats. The PD shape was tubular (48/84), tapered (34/84), or beaded (2/84) with no significant difference (P = 1.0 to .1615) between groups. Mean maximal PD diameters of normal cats were 1.5‐1.7 mm, which was significantly larger in the body of the pancreas in cats with an elevated fPLI (2.4 mm, P = .0313). Mean PD:parenchyma was not significantly different between groups (P = .2001 to .949). In conclusion, the feline PD can be consistently identified on CT, for which the portal phase is preferred. Cats with an elevated fPLI are more likely to exhibit dilation of the PD in the body of the pancreas on CT.     

Description of the use of contrast‐enhanced ultrasonography in four dogs with pancreatic tumours

Canine pancreatic tumours are rare compared to human medicine and the detection and differentiation of pancreatic neoplasia is challenging with B‐mode ultrasonography, which often leads to late clinical diagnosis and poor prognosis. This case report describes the findings of contrast‐enhanced ultrasonography in four dogs with pancreatic adenocarcinoma or insulinoma. B‐mode ultrasonography of the pancreas revealed a hypoechoic nodule in three dogs and heterogenous tissue in one dog. Contrast‐enhanced ultrasonography was able to differentiate between two tumour types: adenocarcinomas showed hypoechoic and hypovascular lesions, whereas insulinomas showed uniformly hypervascular lesions. Contrast‐enhanced ultrasonography findings were confirmed by cytology and/or histopathology. The results demonstrated that contrast‐enhanced ultrasonography was able to establish different enhancement patterns between exocrine (adenocarcinoma) and endocrine (insulinoma) tumours in dogs .     

PRE‐ AND POSTTREATMENT ULTRASONOGRAPHY OF THE THYROID GLAND IN HYPERTHYROID CATS

Ultrasonography is useful for assessing the morphology of the thyroid gland in hyperthyroid cats. Our aim was to describe the ultrasonographic changes of the thyroid gland in hyperthyroid cats after ¹³¹I therapy. Ultrasonography was performed in 15 hyperthyroid cats at initial presentation and 6 months after ¹³¹I using a multifrequency linear transducer set at 12 MHz. The following criteria were evaluated: length, width, height, volume, shape, homogeneity, and vascularity, using Power Doppler. Pretreatment, 10 cats had bilaterally abnormal thyroid lobes, four cats one abnormal lobe with the contralateral lobe being normal or reduced in size, and one cat with one normal lobe and one lobe not visible. Six months after ¹³¹I therapy, there was a reduction in median volume from 819 to 210 mm³, reduced rounding, reduced heterogeneity, and decreased vascularity. In conclusion, ultrasonography may be used to monitor thyroid changes in order to assess ¹³¹I treatment response. Further studies are necessary to determine whether ultrasonography could contribute to the detection of a relapsing course of hyperthyroidism.     

CONTRAST‐ENHANCED ULTRASOUND OF THE FELINE KIDNEY

Contrast‐enhanced ultrasound offers a noninvasive means of subjectively and quantitatively evaluating renal perfusion in cats with renal disease, or in renal transplant patients. In this study, we characterized the pattern of ultrasonographic contrast enhancement in 16 normal feline kidneys in eight cats using contrast‐enhanced power Doppler and contrast‐enhanced harmonic ultrasound techniques. Mean time to peak contrast enhancement for the whole kidney was longer using contrast‐enhanced harmonic ultrasound (16.8s, SD 4.7s) than contrast‐enhanced power Doppler ultrasound (12.2s, SD 1.8s). The time to peak enhancement for the cortex alone in contrast‐enhanced harmonic ultrasound was 13s (SD 3.2s), and for the renal medulla was 25.5s (SD 8.7s). The half time for washout of contrast agent was 39s (SD 14.5s) for contrast‐enhanced harmonic ultrasound. The pattern of contrast enhancement in these normal feline kidneys can be used as normal reference values for the evaluation of clinical patients. Contrast‐enhanced harmonic ultrasound may allow the differentiation between cortical and medullary perfusion patterns.     

Comparison of gel column agglutination with monoclonal antibodies and card agglutination methods for assessing the feline AB group system and a frequency study of feline blood types in northern Italy

Background: A new commercial gel column agglutination system is reported to have high sensitivity in detecting cats with blood type AB. Objectives: The aims of this study were to compare gel column agglutination and card agglutination methods for feline blood‐typing and to determine the frequency distribution of feline blood types in northern Italy. Methods: Blood‐typing was performed on 120 cats using both a commercial gel column containing monoclonal antibodies (ID Gel‐Test Micro Typing System) and a card agglutination method (RapidVet‐H Feline). Results were confirmed with back‐typing. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated for the 2 methods. A second group of 140 Domestic Shorthair (DSH) cats was blood‐typed using the gel column technique to determine the frequency distribution of feline blood types in northern Italy. Results: The card agglutination method demonstrated poor sensitivity in identification of type‐AB cats (61%) and was only 95% specific when identifying type‐B cats. The gel column agglutination technique demonstrated 100% sensitivity and specificity for typing all 3 blood types (A, B, and AB). The frequency distribution study of 140 cats demonstrated that 127 (90.7%) cats were type A, 10 (7.1%) were type B, and 3 (2.1%) were type AB. Conclusion: When blood‐typing cats of breeds with a relatively high frequency of blood types B and AB, methods that use monoclonal antibodies for detection of blood types B and AB are recommended. Alternatively, blood type can be confirmed by more sensitive supplemental testing, such as back‐typing. The high frequency of blood type A in DSH cats in northern Italy was comparable to previously reported frequencies in Italy and world‐wide.     

EVALUATION OF THE FELINE PANCREAS USING COMPUTED TOMOGRAPHY AND RADIOLABELED LEUKOCYTES

This study was designed to test the feasibility and utility of computed tomography and radiolabeled granulocytes in evaluating the feline pancreas in six normal cats. Autologous granulocytes were labeled with 99mTc-hexamethylpropyleneamine oxime (HMPAO) and injected into each cat. Whole body scintigraphic images were acquired at 1, 5, 15, and 30 minutes, and 1, 2, and 4 hours following injection. The following day, each cat was anesthetized and computed tomographic images of the abdomen were acquired both pre- and post-contrast. Following CT, a surgical pancreatic biopsy was collected. Feline granulocytes were successfully labeled with 99mTc-HMPAO with a labeling efficiency of 15-42% (average of 27%). An average of 5.42 x 10(7) cells in a 2 mL volume were injected into each cat. Less than 1 minute was required to acquire 500,000 count images. Granulocytes distributed predominantly to the lung, spleen and liver in order of decreasing activity. Only background activity was identified in the region of the pancreas. The pancreas was easily identified on CT images of the abdomen. The pancreas was hypoattenuating relative to both the spleen and liver. The pancreas enhanced with the administration of contrast medium, peaking immediately, then gradually clearing over the 30-minute test period. Following contrast medium administration the pancreas remained hypoattenuating relative to the spleen. All biopsies confirmed the absence of pancreatic inflammation in the study cats and no adverse effects were recognized as a result of pancreatic biopsy. Both computed tomography and radiolabeled granulocytes appear to hold promise as imaging procedures for the detection of feline pancreatitis. We predict that these described normal parameters may be altered in the face of inflammation, facilitating detection of feline pancreatitis. Data from cases of suspect feline pancreatitis are needed to evaluate these methods for clinical utility.     

Ultrasonographic findings in cats with clinical,gross pathologic,and histologic evidence of acute pancreatic necrosis: 20 cases (1994-2001)

OBJECTIVE: To determine ultrasonographic findings in cats with clinical, gross pathologic, and histologic evidence of acute pancreatic necrosis. DESIGN: Retrospective study. ANIMALS: 20 cats. PROCEDURE: Ultrasound reports and permanent ultrasonographic images were reviewed, and ultrasonographic findings were recorded. Thoracic and abdominal radiographs were also reviewed, when available. Anatomic localization of pancreatic necrosis was determined from the gross pathology report; duration and severity of pancreatic necrosis were determined by reviewing histologic specimens. The presence of concurrent disease was recorded from the final pathology report. RESULTS: The pancreas was considered ultrasonographically normal in 10 cats and was not observed in 3. Ultrasonographic findings were considered compatible with pancreatitis in the remaining 7 cats. Gross pathologic findings indicated that pancreatitis was multifocal in all 7 of these cats; histologically, pancreatitis was acute or subacute in 5 and associated with severe or moderate necrosis in 6. In the remaining 13 cats, gross pathologic findings indicated that pancreatitis was multifocal (n = 8) or focal (2), or gross pathologic findings were normal (3). Histologically, pancreatitis was peracute or acute in 11 of these 13 cats and associated with severe or moderate necrosis in 8. Thoracic and abdominal radiographic findings were nonspecific. CONCLUSIONS AND CLINICAL RELEVANCE: Results of ultrasonography were consistent with a diagnosis of pancreatitis in only 7 of 20 cats with acute pancreatic necrosis in the present study. This suggests that new diagnostic criteria must be established if abdominal ultrasonography is to be an effective tool in the diagnosis of pancreatitis in cats.     

Pancreatitis in cats: diagnosis and management of a challenging disease

Feline pancreatitis can be a very difficult disease to diagnose and often requires a combination of clinical suspicion, appropriate physical examination findings, elevations in serum feline pancreatic lipase immunoreactivity, and changes on abdominal ultrasonography consistent with pancreatic disease. The diagnostic difficulties encountered are related to a lack of specific and readily attributable clinical signs in cats. The sensitivity and specificity of the diagnosis of pancreatitis are highest when a combination of tests is utilized; but even when such tests are employed, the diagnosis is still problematic, especially in cats with chronic pancreatitis. Therapy is symptomatic and focuses on maintaining fluid volume, controlling pain and vomiting, preventing infection, and adjusting to changes in the cat's condition as they occur.     

Measurements of hypoxia ([18F]‐FMISO, [18F]‐EF5) with positron emission tomography (PET) and perfusion using PET ([15O]‐H2O) and power Doppler ultrasonography in feline fibrosarcomas*

The aim of this study was to evaluate if hypoxia in feline fibrosarcomas can be detected. This was done using positron emission tomography (PET), two hypoxia tracers and polarographic pO₂ measurements. Of the seven cats included, five received [¹⁸F]‐fluoromisonidazole and two 2‐(2‐nitro‐1H‐imidazol‐1‐yl)‐N‐(2,2,3,3,3‐pentafluoropropyl) acetamide. Perfusion was evaluated with [¹⁵O]‐H₂O (n = 4) and with contrast‐enhanced power Doppler ultrasonography (n = 5). Hypoxia was detected in three cats. Polarographic pO₂ measurements did not confirm PET results. In the ultrasonographic evaluation, low vascularity and low perfusion were seen with a peripheral vascular pattern and no perfusion in the centre of the tumour. This was in contrast to the [¹⁵O]‐H₂O scans, where central perfusion of the tumour was also found. In conclusion, it appears that hypoxia exists in this tumour type. The presence of tumour necrosis and heterogeneous hypoxia patterns in these tumours may explain the found discrepancies between the applied techniques.     

ULTRASOUND ELASTOGRAPHY OF THE LIVER,SPLEEN, AND KIDNEYS IN CLINICALLY NORMAL CATS

A large amount of overlap exists in the B‐mode ultrasound appearance of normal and abnormal liver, spleen, and kidney tissues in cats. Therefore, invasive tissue sampling procedures remain the standard method for diagnosing diseases in these organs. The purpose of our study was to assess the feasibility of ultrasound elastography as a technique for improving noninvasive characterization of the feline liver, spleen, and kidneys. Elastography was performed on 10 unsedated, clinically healthy cats. Numeric (strain) values (0 = softest to 255 = firmest) assigned to color pixels within regions of interest resulted in median scores (interquartile ranges) of body wall, 207.50 (189.75–224.00); liver, 119.00 (105.00–138.25); spleen, 127.50 (121–00–142.00); right renal cortex, 83.50 (64.00–130.00); right renal near field, 125.50 (110.75–139.75); left renal cortex, 77.50 (52.00–116.25); and left renal near field, 126.00 (114.00–145.25). Strain values were not different between organs. Body wall median was the only significantly different value (P < 0.05). Strain ratio values of body wall:organ were as follows: liver, 1.76 (1.38–2.00); spleen, 1.68 (1.47–1.83); right renal cortex, 2.31 (1.61–3.15); right renal near field, 1.62 (1.41–2.01); left renal cortex, 2.66 (1.45–4.13); and left renal near field, 1.51 (1.29–1.89). Subjectively, hepatic and splenic parenchymal tissues were homogeneous in compressibility and similar in elasticity to one another. Renal cortical tissue was softer compared to medullary tissue. Findings indicated that ultrasound elastography is a feasible technique for objectively and subjectively characterizing the feline liver, spleen, and kidneys. Further research is needed in cats with confirmed diseases of these organs, to compare the diagnostic sensitivity of ultrasound elastography vs. B‐mode ultrasonography.