COMPUTED TOMOGRAPHY-GUIDED PERCUTANEOUS BIOPSY IN THE DOG AND CAT: DESCRIPTION OF TECHNIQUE AND PRELIMINARY EVALUATION IN 14 PATIENTS

A technique for computed tomography (CT)-guided percutaneous biopsy described for use in humans was adapted to the dog and cat and is evaluated in 14 patients. Nine retrobulbar, 1 cranial mediastinal and 4 pulmonary masses and 1 hilar lymph node were biopsied in 13 dogs and 1 cat. Tissue samples sufficient for diagnosis were obtained in 12 of the 15 lesions. Diagnoses were made following cytologic (3/12) or histopathologic (3/12) evaluation or both (6/12) and included retrobulbar lymphoma, carcinoma, spindle cell sarcoma and suppurative inflammation; pulmonary carcinoma, granuloma and eosinophilic/histiocytic inflammation; nasal carcinoma, thymoma and metastatic carcinoma of a hilar lymph node. In each patient, the needle tip was identified within the lesion on the CT image. The primary limitation was non-diagnostic samples in 3 of 15 lesions due to necrosis or insufficient tissue. Complications were minor. In addition to biopsy guidance, CT imaging provided information not obtainable with fluoroscopy or ultrasonography which assisted in tumor staging and therapy planning. Although a larger number of patients and biopsy locations would be required for a thorough assessment, the free-hand technique described in this preliminary report appeared to be a safe and useful option of biopsy guidance in the dog and cat.     

THE TECHNIQUE OF PERCUTANEOUS ULTRASOUND GUIDED FINE-NEEDLE ASPIRATION BIOPSY AND AUTOMATED MICROCORE BIOPSY IN SMALL ANIMAL GASTROINTESTINAL DISEASES

Techniques for obtaining percutaneous ultrasound-guided biopsies of the gastrointestinal tract were evaluated. The efficacity of ultrasonographic detection of gastrointestinal lesions has been established in veterinary medicine. Percutaneous ultrasound-guided aspiration biopsies were performed using either a 22 gauge spinal needle or a 20 gauge Westcott needle. The microcore automated biopsy was performed using a 18 gauge Tru-cut-like needle, assisted by an automated biopsy gun. These techniques are rapid, and easily performed. The techniques were considered safe for the patient, no complications such as hemorrhage, peritonitis or abscessation have occured in our study. These techniques are of particular interest when lesion can not be biopsied successfully by endoscopy and when surgical resection is not recommended.     

FLUOROSCOPICALLY GUIDED PERCUTANEOUS FINE-NEEDLE ASPIRATION BIOPSY OF THORACIC LESIONS IN DOGS AND CATS

Forty-eight fine-needle aspiration biopsy specimens of intrathoracic lesions were obtained with a Westcott needle by localizing needle placement using TV-monitored, image-amplified fluoroscopy and by detecting changes in tactile sensation. Thiryt-five lesions were pulmonary in origin and 13 were within the mediastinum. Most biospy specimens were obtained with the patients sedated, however, general anesthesia was used in one patient to prevent movement that could have resulted in puncture of a critical structure. The only clinical and radiographic complication from this procedure was pneumothorax, occurring in eight dogs and resulting in one death. Definitive diagnoses were made from tissue obtained from 37 of the 48 lesions sampled for a sensitivity rate of 77.1%. Fine-needle aspiration biopsy was found to be a simple, safe, and accurate diagnostic technique.     

CT-guided stereotactic brain biopsy using the Kopf stereotactic system

This report describes computed tomography (CT)-guided stereotactic brain biopsy using the Kopf stereotactic system, a commercially available patient restraint system which does not require additional modification for use in small animals. The accuracy of biopsy needle placement was determined by injecting dilute iohexol into cadaver brains and comparing the three-dimensional coordinates of the desired target location to the actual needle tract observed on postcontrast CT images. Overall mean error in needle placement in a dorsoventral trajectory was 0.9 +/- 0.9 mm (n = 80 injections) for dogs and 1.0 +/- 1.1 mm (n = 30 injections) for cats. The overall mean error in needle placement via an oblique trajectory in five dogs was 1.7 +/- 1.6 mm (n = 12 injections). These results suggest that this system can be used to successfully place a biopsy needle into the brain to obtain biopsies from small lesions.     

Diagnostic accuracy of pre‐treatment biopsy for grading soft tissue sarcomas in dogs

Histologic grade is an important prognostic factor for both local recurrence and metastatic potential with canine soft tissue sarcoma (STS). Pre‐treatment biopsy with identification of tumour grade may aid in prognostication and determination of surgical margins necessary for local control. The purpose of this study was to evaluate the grading accuracy of various pre‐treatment biopsy techniques (wedge, punch, needle‐core) for STS in dogs. Medical records of 68 dogs diagnosed with a STS via pre‐treatment biopsy and confirmed by excisional biopsy were evaluated. The concordance in grade between excisional and pre‐treatment biopsies was 59%. Of the 41% that lacked concordance, 29% of pre‐treatment biopsies underestimated and 12% overestimated grade. The method of pre‐treatment biopsy did not significantly effect grade concordance. Based on these data, needle‐core biopsy appears to be similar in accuracy compared to open biopsy, however, grading determined by pre‐treatment biopsy in general should be interpreted with caution.     

ULTRASOUND-GUIDED FINE-NEEDLE ASPIRATION

A simple and inexpensive modification of the ultrasound-guided fine-needle aspiration biopsy technique using an extension tube attached to the needle is described. One operator can easily manipulate the ultrasound transducer and biopsy needle while monitoring the entire procedure. This simple modification was found to facilitate ultrasound-guided fine-needle aspiration.     

ULTRASOUND LOCALIZATION AND GUIDANCE FOR RENAL BIOPSY IN THE HORSE

Real-time ultrasonography was used to assist percutaneous renal biopsies in seven normal horses. Ultrasound (US) guidance and blind biopsy following US localization were compared. Ten biopsies (seven right kidney and three left kidney) were performed. A transverse approach to the lateral border of the right kidney through the 17th intercostal space was favored, with the needle angle being approximately perpendicular to the body wall. Both biopsy techniques were effective, but blind biopsy following US localization was favored as it was easily performed by one operator without the need for specialized biopsy equipment. The spleen had a variable location and its penetration with the biopsy needle was necessary to obtain two left kidney biopsies. Macroscopic and microscopic hematuria was observed postbiopsy in one and four horses, respectively, out of six horses examined. Perirenal hemorrhage was a prominent finding on necropsy in five of six horses euthanized.     

Renal biopsy in the normal cat: development of a modified disposable biopsy needle

A disposable biopsy needle was modified to reduce the length of the obturator tip and specimen notch. The modified needle was then used to take renal biopsy specimens at four sites from each kidney in four cats. Twenty-nine samples of renal tissue were obtained and the average numbers of glomeruli per specimen length compared favourably with similar studies using the standard needle.     

Percutaneous lung biopsy in the horse: comparison of two instruments and repeated biopsy in horses with induced acute interstitial pneumopathy

The aim of the study reported here was to compare complications of lung biopsy in horses and the quality of the lung specimens after biopsy using the manual Tru-Cut biopsy needle (TC) and an automated biopsy needle (ABN). For experiment 1, lung biopsy was performed in 50 horses with one instrument on one side of the thorax, and then with the other instrument on the other side. Postmortem examination was performed in 20 of the 50 horses. Coughing was detected in 10 of 50 horses and epistaxis was observed in 6 of the 50 horses. Endoscopy revealed bleeding into the airways in 16 of 49 horses and in 5 of 49 horses after biopsy with the TC or the ABN, respectively. Use of the ABN induced a significantly smaller amount of bleeding. Pneumothorax was detected by radiography in 1 of 50 horses. Hematoma diameter determined in 7 of 20 horses at postmortem examination, was significantly larger after biopsy with the TC than with the ABN. The quality of the lung specimen was good. In experiment 2, complications after repeated and multiple lung biopsies in 6 horses were evaluated. Moderate epistaxis was observed on 13 of 104 occasions. Bleeding into the airways was detected at endoscopy on 41 of 104 occasions, and pneumothorax was detected during 4 of 104 occasions. Complications such as hematoma at the biopsy site and bleeding into the airways were greater after biopsy with the TC than after use of the ABN. Lung biopsy specimens obtained with the ABN were fairly safe for the animal.     

A NEW DEVICE FOR STEREOTACTIC CT-GUIDED BIOPSY OF THE CANINE BRAIN: DESIGN, CONSTRUCTION, AND NEEDLE PLACEMENT ACCURACY

An inexpensive device was created for computed tomographic (CT)-guided stereotactic biopsy of the canine brain. The accuracy of the device was tested using 16, formalin-perfused, canine head specimens. For each dog, a 6-inch biopsy needle was guided into pituitary gland and caudate nucleus targets. Needle tracks were measured using the CT computer and infused with tissue staining solution. Hit success and actual needle track lengths were determined from sliced brain specimens. The device enabled accurate orientation and placement of the canine head in the slice plane, such that progressive penetration of the biopsy needle could be monitored. The caudate nucleus was hit 12/16 times (75% accuracy) and the pituitary gland 15.5/16 times (98.6% accuracy). Hit proportions for the two targets did not differ (P < 0.05). A significant difference was found between CT and actual track length for both targets (P < 0.01). This was attributed to incomplete staining of the bevel portion of the needle track.     

LAPAROSCOPIC ULTRASONOGRAPHY IN SIX DOGS

The aim of this study was to describe the technique of laparoscopic ultrasonography in six dogs with intra-abdominal disease. Investigation of the abdominal cavity was undertaken initially in each dog by laparoscopy alone. After exploration and visualization of a diseased organ, a 7.5 MHz microconvex ultrasound probe was introduced into the abdomen through a laparoscopic cannula for videoguided ultrasound examination. Laparoscopic ultrasonography allows core biopsy or needle aspiration to be performed by guiding the needle into nonsuperficial lesions, where videoendoscopic guidance alone is not enough. In addition, color Doppler ultrasonography is useful to examine the vascular pattern to minimize or eliminate complications when a biopsy is performed.     

Diagnostic accuracy of pre‐treatment biopsy for grading cutaneous mast cell tumours in dogs

Mast cell tumours (MCTs) are common tumours of the canine skin, and are estimated to represent up to 20% of all skin tumours in dogs. Tumour grade has a major impact on the incidence of local recurrence and metastatic potential. In addition to helping the clinician with surgical planning, knowledge of the tumour grade also assists in proper prognostication and client education. For pre‐treatment biopsies to be useful, there must exist a high level of correlation between the histopathological grade obtained from the pre‐treatment biopsy and the actual histopathological grade from the excisional biopsy. The aim of this study was to determine concordance of tumour grade between various biopsy techniques (wedge, punch, needle core) and the “gold standard” excisional biopsy method. We found an overall concordance rate of 96% based on the Patnaik grading system, and an overall concordance rate of 92% based on the Kiupel grading system. The accuracy of the various biopsy techniques (wedge, punch and needle core) when compared with excisional biopsy was 92%, 100% and 100%, respectively, based on the Patnaik grading system, and 90%, 95% and 100%, respectively, based on the Kiupel grading system. Of the cases with discordant results, the pre‐treatment biopsies tended to underestimate the grade of the tumour. Based on these results, we conclude that pre‐treatment biopsies are sufficiently accurate for differentiating low‐grade from high‐grade MCTs, regardless of biopsy technique or tumour location.     

COMPARISON OF GLOMERULAR NUMBER AND SPECIMEN LENGTH OBTAINED FROM 100 DOGS VIA PERCUTANEOUS ECHO-ASSISTED RENAL BIOPSY USING TWO DIFFERENT NEEDLES

Our objective was to evaluate possible differences in the number of glomeruli and length of renal biopsies collected in canine subjects by two different types of biopsy needles: a semiautomatic 18-gauge Trucut and an automated 18-gauge Jamshidi modified (Biopince). One hundred biopsy samples obtained from dogs of different ages and gender affected by different nephropathies were evaluated retrospectively. All animals were biopsied using one of the two different needles. Biopsies were performed under ultrasound guidance and evaluated by a single pathologist. Statistical analysis was performed to evaluate possible differences in the number of glomeruli and length of renal biopsies collected comparisons were determined between subgroups of dogs with or without the identification of renal interstitial infiltrates and/or fibrosis. Neither the mean difference of the number of glomeruli nor the length of tissue sample collected with the different needles was significantly different. Likewise, the average biopsy length did not differ in dogs with or without renal interstitial infiltrate in animals biopsied with either biopsy needle. Both the Biopince and the Trucut devices provide diagnostically adequate biopsy renal specimens using ultrasound-guidance.     

Development of a teaching laboratory aid for instruction of fine needle aspiration biopsy cytology technique

Specialized training is required to obtain adequate cytology smears by needle aspiration biopsy. An educational method that would provide opportunity for numerous trainees to acquire needle aspiration biopsy and cytodiagnostic skills, and which would not result in the interruption of teaching hospital patient care nor result in the use or sacrifice of animals from laboratory animal resources was sought. An aspiration biopsy cytology teaching aid was developed by placing portions of fresh organ tissue from routine submissions to the necropsy laboratory into a specimen container partially filled with chilled normal saline solution. Specimens were stored immersed in saline at 4 degrees C for up to 48 hours. Prior to the cytopathology teaching laboratory period, the specimen container was removed from storage and covered with a latex diaphragm. Instructors responsible for teaching cytodiagnostic techniques used this ex vivo aspiration biopsy cytology device for instruction of fine needle aspiration biopsy, specimen processing, and microscopy. In the teaching laboratory, puncture of the diaphragm and aspiration of a tissue sample with hypodermic needle and syringe was instructed to, and practiced by, numerous trainees simultaneously using clinical operative technique without the need for live animals. Trainees prepared and stained cytology smears as well as evaluated and interpreted specimens in a single, realistic exercise. Such training experience may improve ability of trainees to procure diagnostic-quality biopsy specimens for cytodiagnosis of lesions from clinic patients.     

SAFETY OF PERCUTANEOUS ULTRASOUND–GUIDED BIOPSY OF RENAL ALLOGRAFTS IN THE CYNOMOLGUS MONKEY: RESULTS OF 348 CONSECUTIVE BIOPSIES

The safety of a technique for ultrasound-guided biopsy of renal allografts was evaluated based on 348 consecutive procedures in cynomolgus monkeys. A spring-loaded biopsy device with an 18G tru-cut biopsy needle was used to biopsy renal allografts in 139 cynomolgus monkeys performed either on clinical indication (n = 95 animals) or as serial protocol biopsies (n = 44 animals) for a total of 348 biopsies. Monkeys having serial biopsies received between 3-9 biopsies per animal. All others received non-protocol biopsies that were performed on clinical indication, and the range was 1-15 biopsies per animal. No life-threatening complications or deaths occurred and there were no clinically detectable minor complications such as macrohematuria. Self-limiting complications such as small arteriovenous fistulas (n = 4, 3-5 mm large) were detected with Doppler ultrasound and resolved hemodynamically after 2-4 weeks. Three animals developed hematomas ranging 4 mm-2 cm in diameter and were no longer sonographically evident 2-4 weeks later. Ultrasound-guided biopsy of renal allografts can be performed with a high degree of safety in small (3-5 kg) laboratory animals such as the cynomolgus monkey and provides a valuable tool for renal transplantation research. Even when cores were taken at two week intervals no major complications occurred and only rarely were clinically irrelevant complications detected. Experience with diagnostic ultrasound, both gray scale and Doppler, is important for both safety and the recognition of complications that may arise.     

ULTRASOUND-GUIDED BIOPSY OF THE CANINE LIVER, KIDNEY, AND PROSTATE

Sixty-nine hepatic, 25 renal, and 16 prostatic biopsies were performed under ultrasound guidance using a biopsy guide. The majority (98 of 110) were tissue-core biopsies. Multiple attempts at obtaining a sample were required; however, in the kidney, the number of attempts was restricted to two. Adequate samples were obtained in 94% (65/69) hepatic, 88% (22/25) renal, and 94% (5/6) prostatic biopsies. Postbiopsy scanning did not demonstrate parenchymal hemorrhage. In three renal and one prostatic biopsy, gross hematuria, noted immediately following biopsy, resolved in 2–3 days. Animals with prostatic disease frequently had hematuria, making evaluation for this complication difficult. One animal died acutely 2 days following prostatic biopsy due to an unrelated problem, a ruptured aortic àneurysm. Complications were not encountered with the liver biopsy procedure. Animals biopsied under sedation tolerated the procedure well. The authors preferred to anesthetize uncooperative animals and those needing kidney biopsy to minimize the likelihood of complications. Problems encountered during the procedure, overlying bowel gas obscuring the target organ or poor visualization of the biopsy needle, were corrected by changing patient or transducer position or the procedure was postponed. The usefulness of the biopsy procedure is illustrated in four case reports.     

Ultrasound-guided serial transabdominal cardiac biopsies in cats

A percutaneous/transdiaphragmatic core needle biopsy technique was developed in cats to obtain serial biopsies from different locations of the left ventricle, through which morphological and molecular changes within the same individual can be studied to unravel the mechanisms of feline cardiomyopathies. Transmural left ventricular myocardial samples were obtained from 29 anesthetized, healthy, adult cats with ultrasound guidance. An 18G automatic biopsy needle was inserted between the last left rib and the sternum through the diaphragm into the thorax. Biopsies were obtained from the left ventricular wall. In five cats, three single biopsies were taken with 4-week intervals. Autopsy was performed on six cats, of which three cats had serial biopsies. In total, 87 biopsies were obtained without long-term effects on cardiac function or structure. The biopsies caused transient single ventricular premature complexes and mild pericardial effusion without tamponade. Necropsy revealed a minimal amount of fibrous connective tissue in the diaphragm and the heart without any significant microscopic lesions in the adjacent muscle tissue. The high quality biopsy material was suitable for morphological and molecular studies. This minimally invasive, ultrasound-guided cardiac biopsy technique thus allows for the safe collection of serial biopsies to study feline cardiomyopathies in an experimental setting.     

Jamshidi needle biopsy for diagnosis of bone lesions in small animals

Sixty-two bone lesions in 59 small animals were biopsied using a Jamshidi-type biopsy needle. In all instances, the Jamshidi needle biopsy diagnosis was confirmed or disputed by results of histologic examination of specimens obtained by surgical resection or by amputation or at necropsy. In 57 of 62 bone lesions, biopsy resulted in an accurate diagnosis of tumor vs nontumor, yielding an accuracy rate of 91.9%. The specific tumor type or lesion type was identified accurately by Jamshidi needle biopsy in 51 of 62 lesions, yielding an accuracy of 82.3%. Of the 62 bone lesions, 48 were intramedullary osteosarcoma and 62.5% of these were subclassified correctly by Jamshidi needle biopsy results as osteoblastic, chondroblastic, fibroblastic, osteoclastic, or poorly differentiated osteosarcoma. Jamshidi needle biopsy was easy, quick, and safe, and its high accuracy rate of diagnosis indicated that it should be a valuable aid for diagnosis of bone lesions in small animals.     

A Comparison of Liver Sampling Techniques in Dogs

Background

The liver sampling technique in dogs that consistently provides samples adequate for accurate histopathologic interpretation is not known.

Hypothesis/Objectives

To compare histopathologic results of liver samples obtained by punch, cup, and 14 gauge needle to large wedge samples collected at necropsy.

Animals

Seventy dogs undergoing necropsy.

Methods

Prospective study. Liver specimens were obtained from the left lateral liver lobe with an 8 mm punch, a 5 mm cup, and a 14 gauge needle. After sample acquisition, two larger tissue samples were collected near the center of the left lateral lobe to be used as a histologic standard for comparison. Histopathologic features and numbers of portal triads in each sample were recorded.

Results

The mean number of portal triads obtained by each sampling method were 2.9 in needle samples, 3.4 in cup samples, 12 in punch samples, and 30.7 in the necropsy samples. The diagnoses in 66% of needle samples, 60% of cup samples, and 69% of punch samples were in agreement with the necropsy samples, and these proportions were not significantly different from each other. The corresponding kappa coefficients were 0.59 for needle biopsies, 0.52 for cup biopsies, and 0.62 for punch biopsies.

Conclusion and Clinical Importance

The histopathologic interpretation of a liver sample in the dog is unlikely to vary if the liver biopsy specimen contains at least 3–12 portal triads. However, in comparison large necropsy samples, the accuracy of all tested methods was relatively low.