Radiographic Positioning. Small Animal Abdominal Radiography. Lecture Outline. Matthew Paek, VMD, MS, DACVR

Transcription

1 Small Animal Abdominal Radiography Matthew Paek, VMD, MS, DACVR 7/30/ Lecture Outline Radiographic technique Introduction to systematic review and principles of interpretation Basic abdominal radiographic anatomy 7/30/ Radiographic Positioning Multiple projections should always be obtained 2 D image of 3 D structures Superimposi on, Summa. on, and Silhouetting of structures Obtain at least 2 orthogonal (90 o ) views Important for lesion localization Additional projections can be helpful 7/30/2018 3

2 Radiographic Positioning For the abdomen, typically 2 projections obtained Ventrodorsal (VD) Lateral projection Left (preferred) or Right (GDV) Lateral Remember Projections named for the direction of the x ray beam through the patient to the film Ventrodorsal: Dorsal recumbency Dorsoventral: Sternal recumbency Right lateral (Left Right lateral): Right side down Left lateral (Right Left lateral): Left side down 7/30/ Radiographic Positioning Include the entire abdomen Cranial extent: Diaphragm Caudal extent: Greater trochanter Large dogs: May not fit on a single radiograph Radiograph the cranial and caudal aspects separately for each view 7/30/ Radiographic Projection Projection obtained at maximal (end) expiration Less superimposition of structures Longer respiratory pause Goal: Take the radiograph with no movement versus Thoracic radiographs Obtained at maximal (peak) inspiration 7/30/2018 6

3 Positioning Aids Trough Sandbags Foam blocks or wedges Sedation Troughs Tape Rope Tape 7/30/ Puppy VD projection Radiographic Positioning Proper positioning is important! Aids in recognition of normal versus pathology Poor radiographs are at best inconclusive and at worst misleading. 7/30/ So now you have a radiograph Confirm appropriate positioning and technique Entire abdomen included Patient is straight VD/DV: Dorsal spinous process on midline superimposed over the vertebrae Lateral: Transverse processes, ilium, and rib heads superimposed (mildly rotated) 7/30/2018 9

4 So now you have a radiograph Check for artifacts Positioning aids, Markers, IV tubes, ECG wires, Collars, etc Wet hair Motion 7/30/ Cat Wet Hair Artifact Cat - Motion Artifact Possible Search Methods Be Consistent Organ systems Body condition Structures outside of the abdomen Abdominal wall Serosal detail, Peritoneal and retroperitoneal spaces Liver Spleen Kidneys Urinary bladder (Prostate, Uterus) Gastrointes nal tract 7/30/2018 Dog 11 Possible Search Methods Be Consistent Organ systems Body condi on Structures outside of the abdomen Abdominal wall Serosal detail, Peritoneal and retroperitoneal spaces Liver (&GB) Spleen Kidneys Urinary bladder (Prostate, Uterus) Gastrointestinal tract 7/30/2018 Dog 12

5 Possible Search Methods Organ systems Be Consistent Body condi on Structures outside of the abdomen Abdominal wall Serosal detail, Peritoneal and retroperitoneal spaces Liver (&GB) Spleen Kidneys Urinary bladder (Prostate, Uterus) Gastrointestinal tract Cecum Colon 7/30/2018 Dog 13 Systematic Approach Describe the radiographic signs (any changes or abnormalities) Roentgen signs Radiographic opacities Skipping this step and going straight to a diagnosis may lead to misdiagnosis! Establish a Radiographic diagnosis Make a list of differential diagnoses Roentgen signs: 1. Location 2. Number 3. Opacity 4. Size 5. Shape 6. Margin 7. Function or functional implications 7/30/ Metal Radiographic Opacities: 1. Air 2. Fat 3. Soft-tissue / Fluid 4. Mineral Factors Affecting Visualization of Abdominal Organs Projection Differences in radiopacity Normal variations 7/30/

6 Factors Affecting Visualization of Abdominal Organs Projection Structures closer to the detector better evaluated Changes in position of gas and fluid Gas goes up, Fluid goes down Alterations from interventions and disease 7/30/2018 Dog 16 Factors Affecting Visualization of Abdominal Organs Differences in radiopacity Most abdominal organs are so ssue opacity Low subject contrast between structures in the abdomen Bone Air Metal Bone Soft tissue and Fluid Fat Dog 7/30/2018 Fat Metal 17 Air Factors Affecting Visualization of Abdominal Organs Differences in radiopacity Abdominal and retroperitoneal fat prevents silhouetting of adjacent soft tissue structures Increased Bone Air Metal Bone Soft tissue and Fluid ST Dog 7/30/2018 Fat Metal 18 Fat Air

7 Cats Factors Affecting Visualization of Abdominal Organs Fat Content Obese Good subject contrast Emaciated Very poor subject contrast 7/30/ Factors Affecting Visualization of Abdominal Organs Normal variations In SIZE Stomach, Colon, Urinary bladder Canine: Spleen In CONTENT Of the GI tract: Gas, Fluid, Food, Feces Body conformation Species, Breed Body condition Respiratory phase 7/30/ Interpreting the Radiograph 7/30/

8 Abdomen Dog 7/30/ Abdomen as a Whole Body condition Affects subject contrast and therefore visualization of organs Abdominal wall Abdominal distension Body wall defects 7/30/2018 Cats 23 Abdomen as a Whole Peritoneum Serosal detail Retroperitoneum Demarcated ventrally by the parietal peritoneum & dorsally by the sublumbar musculature Extends caudally to the pelvic inlet Kidneys, ureters, adrenal glands, aorta, caudal vena cava, sublumbar lymph nodes cisterna chyli 7/30/

9 Serosal Detail The ability to see the serosal margins of abdominal viscera due to the presence of outlining fat Alterations may be focal or diffuse 7/30/ Dog Serosal Detail Fat Cat Very good serosal detail Very Thin (Cachectic) Cat 7/30/2018 Poor serosal detail 26 Serosal Detail Causes of decreased serosal detail Poor technique Underexposure Immaturity Young dogs and cats due to brown fat Lack of abdominal fat Thin or poor body condition, Emaciation, Cachexia Peritoneal effusion (any type of fluid) Mass effect Mass or enlarged structure results in displacement and silhouetting of adjacent organs Peritonitis Carcinomatosis 7/30/

10 Serosal Detail Mottled serosal detail Ground glass appearance Differential diagnoses: Peritonitis Carcinomatosis Ground glass 7/30/ Dog Serosal Detail Increased Serosal Detail (free abdominal gas) Differential diagnoses: Perforated Intestine Gas Producing Bacteria Penetrating Wound Recent Laparotomy Ground glass 7/30/ Dog 8 year old Germ Shep PC: abdominal distension and retching Intestinal Perforation 7/30/

11 Abdominal Organs Visible organs Gastrointestinal tract Portions of the stomach, small intestines, and large intestine Liver Ventral and caudal ventral margins Spleen Especially in dogs Kidneys In dogs, especially the left Urinary bladder Prostate (Intact male dogs) 7/30/ Abdominal Organs Not routinely visualized Gallbladder Pancreas Sometimes seen in fat cats on VD projection Lymph nodes Adrenal glands Ovaries Uterus Prostate (Cats or neutered dogs) 7/30/ Gastrointestinal Tract Stomach Small intestines Colon 7/30/

12 GI Tract Stomach Cardia and Fundus Left craniodorsal abdomen Caudal to the left diaphragmatic crus Body Ventral Pyloric antrum (canal) Right ventrolateral abdomen 7/30/ GI Tract Stomach Appearance depends on Radiographic projection Species and Body conformation Gastric contents 7/30/ GI Tract Stomach Radiographic projection Location of the gas and fluid changes with patient position Anatomy Gravity Gas goes up, Fluid goes down Can help identify the projection RIGHT LEFT 7/30/

13 Right Lateral Radiograph RLR Gas in Fundus Fluid in Antrum 7/30/2018 Cr 37 Left Lateral Radiograph Gas in Antrum Fluid in Fundus LLR 7/30/2018 Cr 38 DV versus VD Gas in Fundus Fluid in body Gas in body (+/- antrum) Fluid in Fundus & Antrum DV VD 7/30/

14 GI Tract Stomach Species Cats VD/DV projection: J shaped The pyloric antrum is on or slightly to the right of midline on the VD/DV Cat Dog 7/30/ GI Tract Stomach Gastric axis Line from the fundus to the antrum Lateral view: Perpendicular to the spine or parallel to the ribs VD/DV: Perpendicular to the spine 7/30/ GI Tract Stomach Body conformation Dogs Gastric axis Barrel chested breeds: Parallel with the ribs Deep chested breeds: Perpendicular to the spine Barrel- Chested Average Deep- Chested Lateral 7/30/ VD View

15 GI Tract Stomach Gastric contents Type Volume (degree of gastric distension) Unless distended, it is normally within the costal arch (rib cage margin) and does not project caudal to the last ribs Dog - Stomach markedly distended with food 7/30/ year old Germ Shep PC: abdominal distension and retching Gastric Dilatation and Volvulus with Gastric Pneumatosis 7/30/ /30/

16 Feline GDV 7/30/ Guinea Pig GDV 7/30/ year old Labradoodle Vomiting and Inappetance Gastric Outflow Obstruction Fruit Pit 7/30/

17 8 year old FS DSH PC: Vomiting and Inappetance Gastric Mass Large Cell Lymphoma 7/30/ GI Small Intestines Duodenum Right sided Proximally is against the caudal surface of the liver Descending duodenum courses parallel to the body wall Dogs: Lateral, adjacent to the body wall Cats: More medial course than dogs Fat Cat 7/30/ Dog GI Small Intestines Jejunum & Ileum Variable position in the mid abdomen Distribution depends on: Body conformation Size, shape, and position of adjacent viscera Distended organs and masses displace the SI Mass effect What projection??? 7/30/

18 GI Small Intestines Obese dogs and cats Intraabdominal fat tends to displace SI into the central midabdomen In obese cats, most located in the right mid abdomen Cat 7/30/ year Lab PC abdominal distension Intraperitoneal Lipoma Cat 7/30/ GI Tract Small Intestines Duodenum - Jejunum - Ileum Contains variable amounts of intraluminal gas Cats have less intraluminal gas Peristalsis Cats: String of pearls What projection??? Cat 7/30/ Barium Upper GI Study R

19 GI Tract Small Intestines Duodenum - Jejunum - Ileum Maximal Diameter (serosa to serosa) Dogs: <1.6x the height of L5 at the midbody (narrowest) < 2 3x the width of a rib < width of an intercostal space *The lateral projection is used to evaluate vertebral body height b c a 7/30/ GI Tract Small Intestines Duodenum - Jejunum - Ileum Maximal Diameter (serosa to serosa) Cats: < 2x the height of L4 at the midbody < 2x the height of the cranial L2 endplate < 12 mm (US) b a *The lateral projection is used to evaluate vertebral body height 7/30/ GI Tract Small Intestines Duodenum - Jejunum - Ileum Maximal Diameter (serosa to serosa) Similar in diameter to each other Abnormal if > 1.5 2x (50 100%) larger than other segments = Two populations (little/normal ones & big ones) (Duodenum may normally be mildly larger than other segments) Duodenum 7/30/

20 3 year old DSHA PC: Vomiting 7/30/ year old Mixed Breed PC: Vomiting Linear foreign body anchored in the stomach 7/30/ Year Old Pitbull PC: Vomiting 7/30/

21 8 year old Germ Shep PC: Vomiting, abdominal pain, recumbent 7/30/ Mesenteric Torsion 7/30/ GI Tract Large Intestines Cecum (c): Right mid, Level of L3 Dogs: cork screw or C shaped Often contains gas Cats: Small, Not usually visible Ascending colon (a): Right mid to cranial Transverse colon (t): Caudal to stomach Descending colon (d): Left Rectum (r): Pelvic canal and caudal Dog Cat 7/30/

22 GI Tract Large Intestines Cecum Colon 7/30/ year old Jack Russel Terrier PC: vomiting and inappetance. Recently ate a cow bone Signs and Symptoms: 7/30/ year old Jack Russel Terrier PC: vomiting and inappetance. Recently ate a cow bone Post Pneumocolonogram Mineral material within the ileum 7/30/

23 7yo Lab Straining to defecate and pacing 7/30/ /30/ /30/

24 7/30/ Liver Cranial abdomen Caudal to and conforms to the diaphragm Caudoventral margin: Right lateral view: Right medial lobe Left lateral view: Left lateral lobe 7/30/ Liver Cranial abdomen Caudal to and conforms to the diaphragm Caudoventral margin: Right lateral view: Right medial lobe Left lateral view: Left lateral lobe 7/30/

25 Liver Quadrate - Near midline, Ventral Left medial - Cranial, Ventral Right medial - Cranial, Ventral Left lateral - Caudal, Ventral Right lateral - Cranial, more dorsal Caudate - Caudal-dorsal 7/30/ Liver Assessment: Does not extend caudal to the costal arch Sharp caudoventral margins (not rounded) Normal gastric axis // to ribs or to spine 7/30/ Liver Assessment: Does not extend caudal to the costal arch ( ) Sharp caudoventral margins (not rounded) Normal gastric axis // to ribs or to spine 7/30/

26 Liver Assessment: Gastric axis Normal: // to ribs, to spine Normal 7/30/ Liver Assessment: Hepatomegaly: Caudal displacement of antrum (gastric axis) Extends caudal to costal arch Rounded margins Hepatomegaly Normal 7/30/ Liver Assessment: Microhepatica: Cranial displacement of antrum (gastric axis) Hepatomegaly Normal Microhepatica 7/30/

27 Case 11 year Mixed Breed PC: Vomiting, abdominal pain, clinician is suspicious of sepsis 7/30/ Hepatic Abscess with Septic Peritonitis 7/30/ Gall bladder Right cranioventral abdomen Not usually seen Cats: When distended, may produce a bulge along the ventral hepatic silhouette Cat 7/30/

28 Gall bladder Right cranioventral abdomen Not usually seen Cats: When distended, may produce a bulge along the ventral hepatic silhouette Differential diagnosis: Hepatic nodule or mass Cat 7/30/ year Mixed Small Breed PC: Lethargy, tachypnea, recent vomiting 7/30/ Emphysematous Cholecystitis Spleen Flat, elongated Dorsal extremity Left, cranial, dorsal, lateral Caudal to the gastric fundus Ventral extremity Dogs: Variable Cats: Not seen ventrally on lateral projection Enlarged if seen along ventral abdomen 7/30/2018 Dog 84

29 Spleen Flat, elongated Dorsal extremity Left, cranial, dorsal, lateral Caudal to the gastric fundus Ventral extremity Dogs: Variable Cats: Not seen ventrally on lateral projection Enlarged if seen along ventral abdomen What projection??? VD 7/30/2018 Dog 85 8 year old Germ Shep PC: Vomiting, abdominal pain Splenic Torsion 7/30/ Kidneys Retroperitoneal Ureters not seen More mobile in cats Dog 7/30/2018 Cat 87

30 Kidneys L1 L2 L3 L4 L5 L6 L7 Retroperitoneal Ureters not seen More mobile in cats Right kidney: More difficult to visualize Adjacent to & silhouettes with caudate liver lobe Cranial margin: Dog: ~ T13 L1 Cat: ~ L1 L2 Dog L1 L2 L3 L4 L5 L6 L7 7/30/2018 Cat 88 Kidneys L1 L2 L3 L4 L5 L6 L7 Retroperitoneal Ureters not seen More mobile in cats Right kidney: Cranial margin: Dog: ~ T13 L1 Cat: ~ L1 L2 Left kidney: Cranial margin: Dog: ~ 1 vertebral body caudal to Right kidney Cat: ~ L1 L3 7/30/2018 Cat 89 Dog L1 L2 L3 L4 L5 L6 L7 Kidneys Kidney size: Ratio: Renal length to L2 body length VD projection Dog: x length of L2 Cats: Intact: x length of L2 Neutered: x length of L2 Dog 7/30/ Cat

31 Kidneys Kidney size: Ratio: Renal length to L2 body length VD projection Dog: x length of L2 Cats: Intact: x length of L2 Neutered: x length of L2 Dog 7/30/ Cat Case 13 year old FS DSH PC: Vomiting, Anorexia, Azotemia 7/30/ Case 13 year old FS DSH PC: Vomiting, Anorexia, Azotemia Renal Lymphoma 7/30/

32 9 yo MN DSH Underlying GI IBD Urinary Bladder Ectopic R Kidney 7/30/ Adrenal Glands Retroperitoneal Craniomedial to kidney Not normally seen Cats: Incidental mineralization Dogs: Mineralization associated with neoplasia Lateral Kidneys Cats 7/30/ Lateral VD 13 year old Beagle PC: Abdominal distension, PU/PD Mineralized Adrenal Mass 7/30/

33 Urinary Bladder Caudal ventral abdomen Cranial to pubis Ventral to descending colon and rectum Cat 7/30/ Urinary Bladder Caudal ventral abdomen Round, Tear or Pear shaped Variably sized Exerts mass effect when large Cat Mass Effect 7/30/ yo MN Scottish Terrier PC: Recurrent urinary tract infections 7/30/

34 12yo MN Scottish Terrier PC: Recurrent urinary tract infections Transitional Cell Carcinoma 7/30/ yo MI Boston Terrier PC: Straining to Urinate/Defecate with a perineal mass What s not there? 7/30/ yo MI Boston Terrier PC: Straining to Urinate/Defecate with a perineal mass Perineal hernia with bladder herniation 7/30/

35 Prostate Dog Caudal abdomen / Cranial pelvic canal Caudal to bladder, Ventral to rectum Not normally seen in cats or neutered dogs 7/30/ Prostate Caudal abdomen / Cranial pelvic canal Caudal to bladder, Ventral to rectum Fat triangle: between body wall (ventral), bladder (caudoventral margin), prostate (cranioventral margin), Not normally seen in cats or neutered dogs Bladder Prostate Dog 7/30/ Prostate Intact male dogs: Lateral: Length or height as % of Pubic brim to sacral promontory dimension Normal: < 70% (mean 56%) VD: < 50% of the pelvic inlet width 7/30/

36 9yo MN Terrier Mix PC: Straining to Urinate & Limping Prostatic Mass with Metastatic Disease 7/30/ yo MN Terrier Mix PC: Straining to Urinate & Limping 7/30/ Thank You 7/30/