Veterinary Image-Guided Interventions

Chick Weisse, Allyson Berent, Chick Weisse, Allyson Berent

• Publisher: Wiley-Blackwell
• Year: 2015
• ISBN:
  9781118378250
• Edition: 1
• Topic: Medicine
• Subtopic: Veterinary Medicine

Veterinary Image-Guided Interventions is the only book dedicated to interventions guided by imaging technology. Written and edited by leading experts in the field, interventional endoscopy, cardiology, oncology and radiology are covered in detail. Chapters include the history and background of the procedures, patient work-up, equipment lists, detailed procedural instructions, potential complications, patient follow-up protocols, and expected outcomes. Split into body systems, the technical aspects of each procedure are presented using highly illustrated step-by-step guides. Veterinary Image-Guided Interventions is a must-have handbook for internists, surgeons, cardiologists, radiologists, oncologistsand criticalists, and for anyone interested in cutting-edge developments in veterinary medicine.

Key features include:

• A highly practical step-by-step guide to image-guided procedures
• Relevant to a wide range of veterinary specialists.
• Written and edited by respected pioneers in veterinary image-guided procedures
• A companion website offers videos of many procedures to enhance the text

SECTION FIVE
Urogenital System

Edited by Allyson Berent

1. 26 Imaging of the Urinary Tract
2. 27 Interventional Management of Complicated Nephrolithiasis
3. 28 Interventional Treatment of Idiopathic Renal Hematuria
4. 29 Interventional Management of Canine and Feline Benign Ureteral Obstructions
5. 30 Interventional Management of Obstructive Pyonephrosis
6. 31 Interventional Management of Canine Malignant Ureteral Obstructions
7. 32 Cystoscopic-Guided Laser Ablation of Ectopic Ureters
8. 33 Minimally Invasive Treatment of Bladder and Urethral Stones in Dogs and Cats
9. 34 Urethral Stenting
10. 35 Endoscopic Polypectomy and Laser Ablation for Benign Urinary Bladder Lesions
11. 36 Intra-arterial Chemotherapy Infusion
12. 37 Ultrasound-Guided Endoscopic Laser Ablation for Transitional Cell Carcinoma in Dogs
13. 38 Injectable Bulking Agents for Treatment of Urinary Incontinence
14. 39 Percutaneous Perineal Approach to the Canine Urethra
15. 40 Percutaneous Antegrade Urethral Catheterization
16. 41 Percutaneous Cystostomy Tube
17. 42 Endoscopic Laser Ablation of Vestibulovaginal Remnants (ELA-VR)

CHAPTER TWENTY-SIX
Imaging of the Urinary Tract

Amy M. Habing and Julie K. Byron

Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, OH

Introduction

Imaging, plain and contrast-enhanced, and uroendoscopy is essential to interventional evaluation and treatment of the urinary tract, and are often best used in combination. Here we review the indications, procedures, complications, and interpretation of some of the most common imaging studies performed for the urinary tract. Table 26.1 offers a quick reference to various non-endoscopic imaging techniques and specific considerations of each study are discussed in the following sections.

Table 26.1

Procedure	Patient preparation	Contrast	Dose/ Volume	Technique	Additional considerations
EU (fluoroscopy/ radiography)	12–24 hr fast +/– Enema Sedation/ general anesthesia IV catheter	Aqueous iodinated (non- ionic preferred)	600–880 mgI/kg Inc. dose by 20% if renal azotemia is present	Survey RT and VD Rapid IV bolus injection RL and VD time 0, 5, 20, 40 minutes Repeat RT and LT OBL as needed starting at 5 minutes for UVJ	Concurrent negative contrast cystogram may be performed for ectopic ureter evaluation If poor filling of the renal pelves, caudal abdominal compression may be applied using a tight elastic bandage after the 5 minute image. Images are made after 5–10 minutes and the bandage is removed. Caudal abdominal compression should not be performed with negative contrast cystogram.
CT EU^8			400–880 mgI/kg Inc. dose by 20% if renal azotemia is present	Position in sternal recumbency with pelvis elevated Survey CT (cranial to kidneys to caudal urethra) Rapid IV bolus injection Repeat scan at time 0, 3 minutes Repeat scans from mid bladder to caudal urethra as needed for UVJ
Ultrasound guided percutaneous pyelogram	12–24 hr fast +/–Enema General anesthesia/ heavy sedation Surgical scrub of skin	Aqueous iodinated	Replace 50–100% of renal pelvic fluid with positive contrast media	Survey RL and VD Using ultrasound guidance, aseptically advance a 22 gauge spinal needle through the renal cortex, and into the dilated renal pelvis Remove approximately 50% renal pelvic fluid and replace with positive contrast RT and V/D time 0, 15 minutes	Repeat bolus injections and images as needed for diagnosis
Positive contrast cystogram	12–24 hr fast +/– Enema Sedation/ general anesthesia Aseptic urinary bladder catheterization with urine removal +/– 2% lidocaine (2–5 ml) injected into urinary bladder to reduce bladder pain/ spasm	20 % aqueous iodinated (diluted with sterile saline/ sterile water)	5–10 ml/kg (dog) 2–5 ml/kg (cat)	Survey RT and VD Inject positive contrast through urinary catheter. RL, VD, RT and LT OBL	Terminate injection if bladder feels turgid and/or back pressure is felt on the syringe plunger
Negative contrast cystogram		Nitrogen or CO2 (preferred), or room air	5–10 ml/kg (dog) 2–5 ml/kg (cat)	Survey LL and VD Inject negative contrast through urinary catheter. LL, VD, RT and LT OBL
Double contrast cystogram		Aqueous iodinated	5–10 ml (dog) 3 ml (cat)	Survey LL and VD Inject positive contrast through urinary catheter Rotate patient to allow adequate coating of the bladder mucosa Place in LEFT lateral recumbency Inject negative contrast through urinary catheter LL, VD, RT and LT OBL
		Nitrogen or CO2 (preferred), or room air	5–10 ml/kg (dog) 2–5 ml/kg (cat)
Urethrogram	Sedation/ general anesthesia Aseptic distal urethral catheterization +/– 2% lidocaine (2–5 ml) injected into urethra to reduce spasm	Aqueous iodinated	10–15 ml (dog) 5–10 ml (cat)	Survey RL and RL with legs pulled forward (male dogs) Inject 50% of contrast media RL with legs forward (image made at end of injection) Inject remaining contrast RL, RL and LT OBL	Urinary bladder should be fully distended to facilitate urethral distension Terminate injection if back pressure is felt on the syringe plunger Foley catheter is preferred in male dogs Red rubber or Tomcat catheter is used in cats and females
Vaginourethrogram	General anesthesia Aseptic vestibule foley catheterization	Aqueous iodinated	10–15 ml (dog) 5–10 ml (cat)	Survey RL and VD Inject 50% of contrast media RL (image made at end of injection) Inject remaining contrast RL and VD	Plastic hemostats are used to clamp vulvar lips around the catheter to prevent contrast leakage The tip of the catheter should be cut to prevent it from extending into the vagina Terminate injection if back pressure is felt on the syringe plunger

*CT technique may vary and should be optimized based on machine (generation), size of patient and question to be answered. At the author’s institution, helical imaging is performed using 125 mAs and 130 kVp. and a pitch of 1.25. Slice thickness ranges from 2.5 mm – 5 mm for both pre and post contrast acquisition, depending on size of patient. Transverse images from the mid urinary bladder through the urethra are obtained using 1.25 mm slice thickness to document ureteral termination. If multi-detector CT is used, images may be reconstructed in thinner slices.

Excretory Urography

Indications

Excretory urography (EU) is of use in a variety of diagnostic scenarios. The study allows for examination of kidney morphology and subjective assessment of renal function. Assessment of the renal pelves and a suspicion of the presence of masses, hematomas, or nephroliths is a frequent indication for EU.

EU may assist in the differentiation between acute kidney injury, chronic renal dysfunction, and renal dysplasia based on the timing and persistence of renal opacification, as well as the morphologic characteristics of the kidneys. Its use in this diagnostic capacity may be limited, however, by the concern around contrast-induced kidney injury and further morbidity in an already compromised patient. Ultrasound-guided percutaneous pyelography is particularly useful in patients that are being evaluated for ureteral disease, avoiding contrast-...