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Principles of radiography

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Abstract

Radiography is the most commonly used diagnostic tool in veterinary practice and has an important role in the diagnosis of rabbit diseases. It is non-invasive and provides the clinician with a large amount of information. This chapter discusses equipment, radiation safety rules, patient positioning, contrast studies and radiographic interpretation. : Myelography

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Figures

Image of 3.1
3.1 Computed digital radiography is commonly used, especially for dental radiography. This rabbit is positioned for a lateral extraoral view of the skull. The open mouth allows evaluation of the occlusal surfaces. A piece of a 2 ml syringe can be cut – approximately 1 cm in length – so that it fits between the incisors.
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3.3 Patient positioning for a DV view of the skull. The rabbit is positioned on the X-ray film and a small box is placed below the mandible to support the head. The patient position can be evaluated from the front, where an imaginary medial head line should be perpendicular to the table.
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3.4 Patient positioning for a rostrocaudal view of the skull. The rabbit is placed in dorsal recumbency with its nostrils pointing upwards. The head is supported with a foam wedge. The X-ray beam should be centred on the middle of the imaginary connecting line between the medial canthus of each eye.
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3.5 Patient positioning for a lateral oblique view of the skull. The rabbit is placed in lateral recumbency; the mouth may be closed or held open. The X-ray tube is then adjusted through a 20–40 degree angle.
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3.6 Lateral oblique views of the left mandible of the rabbit in Figure 3.5 . Note that in the 40 degree view a larger part of the premolar and molar reserve crowns can be seen compared with the 20 degree view.
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3.7 Intraoral dental radiograph of the left mandibular arcade obtained using the parallel technique. All the tooth structures and the alveolar bone are visible in high detail. The last two molars were examined. For a detailed examination of the premolar apices, the film would need to be slightly repositioned. (Indirect digital radiography; film size = 20 × 30 mm; scanner = Durr CR 7 VET)
Image of 3.8
3.8 Intraoral dental radiographs of the mandibular incisors (left) and maxillary incisors (right) obtained using the bisecting angle technique. The maxillary peg teeth are missing in this patient. (Indirect digital radiography: film size = 27 × 54 mm; scanner = Durr CR 7 VET)
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3.9 Patient positioning for a DV view of the thorax. The X-ray beam is centred on the area of interest.
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3.10 Patient positioning for a right lateral view of the thorax. The X-ray beam is centred on the area of interest.
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3.11 Patient positioning for a craniocaudal view of the elbow joint. The head is elevated and retracted away from the affected limb. The X-ray beam is directed distoproximally at a 10–20 degree angle and is centred on the medial epicondyle.
Image of 3.12
3.12 Patient positioning for a dorsopalmar view of the metacarpus and digits. The rabbit is in sternal recumbency with the elbow joint positioned ventral to the body, allowing the carpus, metacarpus and digits to be parallel with the cassette without any anatomical distortion.
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3.13 VD view of the pelvis with craniocaudal view of both femurs.
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3.14 Mediolateral view of the right hind paw of a rabbit. The image is achieved by taping each individual digit in a different position. The rounded opacities are soil particles embedded in the rabbit’s fur and the radiodense lines at the bottom of the image are produced by the tape. (Indirect digital radiography: film size = 57 × 76 mm; scanner = Durr CR 7 VET)
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3.15 Patient positioning for a plantodorsal view of the right metatarsus. The rabbit is placed in sternal recumbency with both legs extended caudally. Each leg can be fixed in position using an elastic bandage or tape. The lateral aspect of the stifle needs to be supported to stabilize the leg. The X-ray beam is centred on the area of interest.
Image of 3.17
3.17 Right lateral view of the pyelographic phase of an excretory urogram taken 5 minutes after the administration of contrast medium. Renal opacity is still visible, which indicates a functional problem. The kidneys are of different sizes and there are nephroliths within the right kidney. Only the left ureter is visible. The radiopaque areas dorsal to the bladder represent regions of fatty tissue calcification.
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3.18 Pre-contrast and post-contrast right lateral radiographs of the normal nasolacrimal duct in a rabbit. The arrows indicate the tortuous route of the contrast medium. A small amount of the contrast medium (iomeprol) can be seen in the nasal cavity.
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3.19 Lateral radiographs of two rabbits with scrotal and ventral abdominal herniation. (a) This radiograph was taken 4.5 hours after contrast medium administration. The contrast medium is located mainly in the caecum and proximal colon. (b) This radiograph was taken 5.5 hours after contrast medium administration. The contrast medium is distributed throughout the gastrointestinal tract. No part of the small intestines, caecum or colon is involved within the herniated tissue in either case.
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3.20 Pre-contrast and post-contrast DV radiographs showing the ear canals in a rabbit. The tympanic membrane in the right ear is intact, whereas the left tympanic bulla is completely filled with contrast medium, indicating that the membrane is perforated.
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3.21 Lateral and VD radiographs of the head of a rabbit showing swelling of the soft tissues (an abscess) in the ventral mandibular area due to foreign body (wire) penetration (arrowed). The length of the wire on the lateral radiograph measured 1 cm, whereas on the VD radiograph it measured 3.5 cm.
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3.22 Right lateral radiograph of the abdomen of a rabbit. All parts of the radiograph should be evaluated to determine whether the features are normal or if there is abnormal pathology. In this case, apart from the obvious urolithiasis (two cystoliths), the uterus is enlarged and the caecum contains gas. The final diagnoses were obesity, cystolithiasis, uterine adenocarcinoma and ileus. The image in has been coloured to show the positions of the colon (blue), kidneys (yellow), liver (brown) and uterus (red).
Image of Lateral and dorsal views of cisterna magna puncture in the rabbit. A needle is inserted into the dorsal midline of the atlanto-occipital region (white arrow), approximately in the middle (blue spot) of a triangle connecting the dorsal tip of the occipital protuberance and the lateral wings of the atlas (C1) vertebra. The correct position is located cranial to the craniodorsal tip of the dorsal spine of the axis (C2) vertebra.
Lateral and dorsal views of cisterna magna puncture in the rabbit. A needle is inserted into the dorsal midline of the atlanto-occipital region (white arrow), approximately in the middle (blue spot) of a triangle connecting the dorsal tip of the occipital protuberance and the lateral wings of the atlas (C1) vertebra. The correct position is located cranial to the craniodorsal tip of the dorsal spine of the axis (C2) vertebra. Lateral and dorsal views of cisterna magna puncture in the rabbit. A needle is inserted into the dorsal midline of the atlanto-occipital region (white arrow), approximately in the middle (blue spot) of a triangle connecting the dorsal tip of the occipital protuberance and the lateral wings of the atlas (C1) vertebra. The correct position is located cranial to the craniodorsal tip of the dorsal spine of the axis (C2) vertebra.
Image of A spinal needle is introduced into the cisterna magna where a slight depression can be palpated.
A spinal needle is introduced into the cisterna magna where a slight depression can be palpated. A spinal needle is introduced into the cisterna magna where a slight depression can be palpated.
Image of Lateral and dorsal views of lumbar puncture in the rabbit. The needle (white arrow) is inserted in a cranioventral direction just caudal to the dorsal spinal process of L6.
Lateral and dorsal views of lumbar puncture in the rabbit. The needle (white arrow) is inserted in a cranioventral direction just caudal to the dorsal spinal process of L6. Lateral and dorsal views of lumbar puncture in the rabbit. The needle (white arrow) is inserted in a cranioventral direction just caudal to the dorsal spinal process of L6.
Image of Spinal canal and spinal needle position. A = correct position. B = spinal cord puncture; the needle should be repositioned dorsally or ventrally. C = the needle should be slightly retracted to achieve subarachnoid puncture. D = correct position.
Spinal canal and spinal needle position. A = correct position. B = spinal cord puncture; the needle should be repositioned dorsally or ventrally. C = the needle should be slightly retracted to achieve subarachnoid puncture. D = correct position. Spinal canal and spinal needle position. = correct position. = spinal cord puncture; the needle should be repositioned dorsally or ventrally. = the needle should be slightly retracted to achieve subarachnoid puncture. = correct position.
Image of Lateral myelograms of a rabbit with hindlimb paresis. No abnormalities were evident. When taking a myelogram it is advisable to include at least two or three regions (cervical, thoracic, lumbar) within the field of view to obtain as much information as possible.
Lateral myelograms of a rabbit with hindlimb paresis. No abnormalities were evident. When taking a myelogram it is advisable to include at least two or three regions (cervical, thoracic, lumbar) within the field of view to obtain as much information as possible. Lateral myelograms of a rabbit with hindlimb paresis. No abnormalities were evident. When taking a myelogram it is advisable to include at least two or three regions (cervical, thoracic, lumbar) within the field of view to obtain as much information as possible.
Image of (a) During a cisterna magna puncture, high pressure was applied, resulting in contrast medium passing into the ventricles of the brain (cadaver specimen). This volume of contrast medium in the CSF of a live rabbit will cause seizures or even death. (b) Myelogram showing leakage of the contrast medium into the surrounding soft tissues as a result of inadequate needle placement.
(a) During a cisterna magna puncture, high pressure was applied, resulting in contrast medium passing into the ventricles of the brain (cadaver specimen). This volume of contrast medium in the CSF of a live rabbit will cause seizures or even death. (b) Myelogram showing leakage of the contrast medium into the surrounding soft tissues as a result of inadequate needle placement. During a cisterna magna puncture, high pressure was applied, resulting in contrast medium passing into the ventricles of the brain (cadaver specimen). This volume of contrast medium in the CSF of a live rabbit will cause seizures or even death. Myelogram showing leakage of the contrast medium into the surrounding soft tissues as a result of inadequate needle placement.
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