Presentation on theme: "Introduction to Thoracic Radiology"— Presentation transcript:
1Introduction to Thoracic Radiology Dr. Meghan WoodlandSeptember 30, 2010.
2Indications Coughing Dyspnea / Tachypnea Heart Murmur, Collapse Primary or Secondary NeoplasiaCheck for metastasisThoracic TraumaChest Wall MassExercise Intolerance, Weight Loss
3Technical Factors Potential for Movement High inherent contrast RespirationDecrease mAsHigh inherent contrastHigh kVpCollimationShould include thoracic inlet to diaphragmCenter over the heartPull thoracic limbs forwardHigh kVp and low mAs will reduce the naturally high contrast in the thorax and increase the lung detail visible.Radiographic techniques: the dog By Joe P. Morgan, John Doval, Valerie Samii
5Patient is rotatedAbdomen should be collimated out
6Determining the Phase of Respiration Always expose at peak inspirationMaximizes lung contrastBetter visualization of pulmonary parenchymaLess compression of lungs by diaphragmInspiratory lateral view:Caudodorsal aspect of lung is caudal to T12Increased aeration of accessory lung lobeSeparation of cardiac silhouette and diaphragmInspiratory VD/DV view:Diaphragmatic cupola caudal to mid-T8Tips of lung caudal to T10In anesthetised patients, it may be necessary to manually inflate the lungs. As well, in sedated/anesthetised patients, you should obtain the DV/VD view before the laterals, because anaesthesia-induced atelectasis may arise quickly after induction. This is especially true in large or overweight dogs.
7Inspiratory vs. Expiratory Lateral Notice size of triangle
8Inspiratory vs. Expiratory VD Easy to see the difference in well visualized lung
9DV vs. VDDVBest view to evaluate cardiac silhouette and caudal pulmonary vesselsLess stressful for the patientDiaphragm roundedSee small amounts of pleural airVDBest view to evaluate lungsHeart appears elongatedFlat diaphragm – Mickey Mouse earsSee small amounts of pleural fluid
17Right vs. Left LateralCaudal Vena Cava enters the right diaphragmatic crusRight LateralBetter cardiac detailR crus forwardSee CVC go into itLeft LateralHeart appears roundL crus forwardSee Cava go pastCaudal vena cava
20The Effects of Lateral Recumbency Lung lesions (mass, nodule, infiltrate) may only be seen on a single viewOnly the non-dependent (up) lung can be critically evaluatedDependent lung loses aeration (atelectasis)Increased opacitySilhouettes with lesionsDependent lung loses aeration because of the increased pressure from mediastinal structures (especially the heart) and the dependent crus of the diaphragm. This is even more increased in anesthetised patients.
22Interpretation of Thoracic Radiographs Systematic approach is crucialHeart (Cardiac Silhouette)LungsMediastinumPleural spaceChest wallBones, Abdomen, NeckStructures seen on thoracic radiographs.Also evaluate for radiographic quality.Don’t forget the extrathoracic structures.
23Normal Cardiac Silhouette Size is subjectiveLateral views:Dog = 2 ½ - 3 ½ intercostal spacesCat = 2 – 2 ½ intercostal spacesVD/DV views:65% the width of the thoraxObjective:Buchanan methodVertebral heart scaleCardiac silhouette includes: pericardium, pericardial fluid, myocardium (including epicardium and endocardium), the origins of major vessels and blood.Size of the cardiac silhouette on radiographs is breed dependent. Barrel-chested dogs such as the Bulldog, Yorkshire Terrier and Dachshund have a relatively large cardiac silhouette on lateral radiographs. Deep-chested dogs, such as the Doberman, have taller, more slender cardiac silhouettes.Vertebral heart scale:On the lateral radiograph, the distance between the ventral aspect of the carina and the cardiac apex is taken as length.The width is the maximum width of the heart perpendicular to the length line.The number of vertebral lengths is taken for length and width, beginning at T4.Dogs: normal = 9.2 – 10.2 (>10.5 is cardiomegaly)Cats: normal = 7.2 – 7.8 (>8.1 is cardiomegaly)
24Clock Face 11-1 Aortic Arch 1-2 Main Pulmonary Trunk 2-3 Left Auricle 2-5 Left Ventricle5-9 Right Ventricle9-11 Right AtriumCentrally – Left Atrium
26Lateral View Make a Plus sign Bermuda triangle Left atrium Right atriumMain pulmonary arteryAortic ArchLeft atriumLeft VentricleRight Ventricle
27Thoracic and Pulmonary Vessels AortaCaudal Vena CavaCranial pulmonary vesselsProximal third ribCaudal pulmonary vesselsWhere crosses 9th ribVeins are ventral and centralArtery, bronchus, veinABV’s
28Trachea, Bronchial Tree Trachea ends at the carinaThen splits to the main stem bronchi followed by the lobar bronchiTracheal rings can mineralize (age)Decreased tracheal diameterTracheal narrowing (stenosis, extramural compression)Tracheal hypoplasiaTracheal collapseExpiratory lateral views are utilized to examine a patient for tracheal collapse.Tracheal hypoplasia is common in certain brachiocephalic breeds, such as the bulldog.
29Lungs Normal anatomy 1 4 2 5 3 6 7 Left Right Cranial (cranial subsegment) 1Cranial (caudal subsegment) 2Caudal 3RightCranial 4Middle 5Caudal 6Accessory 71425367
35The Diaphragm Cupola Right and left crura Cranioventral convex portionRight and left cruraAttach to cranioventral border of L3 and body of L4May cause irregularity on these surfacesAppearance depends on centering of X-ray beam