A Cardiologist s Approach to Thoracic Radiology Kacie Schmitt Felber, DVM, DACVIM Cardiology Thursday, May 17 th, 2018 Mid Atlantic States Veterinary Clinic Conference Outline Technique Principles of interpretation Case Examples Technique Optimize image quality Machine settings Positioning Artifacts Effect of recumbency Effect of aeration Patient movement Patient positioning 1
Technique: Optimize Image Quality Thorax has high inherent subject contrast Primarily air and soft tissue Looking for subtle changes in opacity Utilize long gray scale High kvp and low mas settings High kvp affords latitude and reduces total mas required for optimal film blackness Low mas minimizes respiratory motion What s wrong? How to correct? Technique: Positioning Keys to success Sternum directly over vertebrae (use padded trough) Legs pulled forward and parallel Ribs superimposed (may need foam pad under sternum) Inspiratory phase of respiration Collimatefor thorax only Contrast Safety for team and patient Minimize artifact 2
What s wrong with these images? Technique: Patient Positioning 3
Technique: Patient Positioning Cat in a Box Radiograph Trick Technique: Positioning Recumbency Problem Profound effect on cardiopulmonary physiology Results in differences in the appearance of R vs L and DV vs VD Results in reduced aeration in down lung Silhouette sign Exacerbated by sedation, anesthesia, and patient size Solution Take on full inspiration Minimize sedation PPV when anesthetized Take orthogonal views Minimal 3 views R and L laterals VD +/ DV 4
Technique: Aeration Technique: Aeration Technique: Patient Movement 5
Importance of multiple views Importance of multiple views Principles of Interpretation Knowledge of normal anatomy Age, breed/conformation, species, cardiac cycle Understanding of radiographic signs of pathology Ex. Heart failure vs. Pulmonary hypertension Develop a systematic approach Is the study of diagnostic quality? 6
What is normal? <3 ICS Avg Dog <3.5 Small Breeds < 2.5 Deep Chested Cats <70% height of chest; < 2 3 ICS Greatest horizontal dimension should be <2/3 chest dimension at that location Cats <50% width of chest Vertebral Heart Scale Normal Anatomy: Cat 7
Normal Anatomy: Dog Normal Anatomy: Dog Breed Variations Thorax Type Lateral View D/V View Wide/shallow Dachshund, Shi Tzu, Boston Terrier, Bulldog Deep/narrow Greyhound, Doberman, Whippet Intermediate German Shepherd, Lab, Golden Shorter/rounder heart Large inclination to the spine Long contact with sternum (mimics RHE) Long/oval heart Vertical position in thorax almost perpendicular to spine Ovoid or lop sided eggshaped Rounded RV/LV borders Apex usually well to the left of the spine Circular silhouette due to upright position Apex close to median plan Similar to lateral Apex is usually slightly to left of spine Wide/Shallow (Barrel) Shorter/rounder heart Increased sternal contact(mimics RHE) Rounded LV/RV borders Apex to left of sternum 8
Wide/Shallow Yorkie Chest Malformation Yorkie Doberman Upright cardiac silhouette Deep/Narrow Greyhound Rounded silhouette Apex on midline Borzoi Elongated cardiac silhouette 9
Intermediate Dogs Increased sternal contact mimicking rightsided cardiomegaly Cardiac size appears normal Apex displaced into left hemithorax Cardiac Cycle Systole Ventricles contracted/smaller Atria dilated Diastole Entire heart more rounded Atrial/auricular bulges less prominent Age 10
Obesity Principles of Interpretation Consider false positive findings Right heart enlargement Dorso caudal rotation of apex in left lateral view Breed variation Alveolar disease Atelectasis Pneumothorax Skin folds Esophageal dilation Sedation Pleural effusion Pleural thickening Cardiomegaly Pericardial effusion PPDH Principles of Interpretation Consider false negative findings Assessing dynamic problem with static images Tracheal collapse / airway disease Hiatal hernia Disclose a hidden dynamic lesion Vary posture or position Inspiration vs expiration Other imaging modality 11
Clinical Cases: Sometimes there is little need for interpretation but more often than not it s not that obvious Clinical Cases Degenerative valve disease Hypertrophic cardiomyopathy Dilated cardiomyopathy Upper and lower airway disease Pulmonary hypertension Pleural effusion Pericardial effusion Pneumothorax Pulmonary masses/nodules 12
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Heart failure or not? Is heart big or does technique/conformation give artifactual appearance of enlargement? Are pulmonary veins dilated? Is infiltrate consistent with CHF? Is there a murmur/gallop and where? If small dog and no loud murmur on left, unlikely CHF If murmur louder on R side, think PHT Is the heart rate fast? Unless hypothermic or Cocker/Schnauzer Is NT probnp elevated? Is there clinical/radiographic response to furosemide? 16
Tracheal Plasmacytoma 17
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2 wk Recheck 19
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Comments / Questions Contact Information: kacie.schmitt@cvcavets.com info@cvcavets.com www.cvcavets.com 24