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MI4 Medical Imaging
Chest Imaging
Toronto Notes 2019
Contrast Enhancement
Table 2. Contrast Agents
Imaging Modality
X-Ray/CT
Types
1. Barium (oral or rectal)
2. Iodine (IV injection)
Gadolinium-Chelates (IV injection)
Microbubbles (IV injection)
Advantages
Radio-opaque substance that helps to delineate intraluminal anatomy; may demonstrate patency, lumen integrity, or large filling defects
Delineates intraluminal anatomy; may demonstrate patency, lumen integrity, or large filling defects; under fluoroscopy, may also give information on function of an organ
Shortens T1 relaxation time, thereby increasing signal intensity in T1- weighted sequences; gadolinium has some effect on T2-relaxation time; highlights highly vascular structures (e.g. tumours)
Since gas is highly echogenic, the microbubbles allow for echo-enhancement of a tissue
Disadvantages
Risk of nephrogenic systemic fibrosis in patients with end-stage renal disease
Risk of nephrogenic systemic fibrosis in patients with end-stage renal disease
Contraindications
Previous adverse reaction to contrast; barium enema is contraindicated in toxic megacolon, acute colitis, and suspected perforation
Previous adverse reaction to contrast, renal failure, DM, pregnancy, multiple myeloma, severe heart failure and dehydration eGFR <60 may require preventative measures and follow-up
Previous adverse reaction to contrast or if end-stage renal disease (relative contraindication)
Contraindicated in individuals with right- to-left cardiac shunts
or people with known hypersensitivity reactions
MRI
U/S
Chest Imaging
Chest X-Ray
Standard Views
• PA:anteriorchestagainstfilmplatetominimizemagnificationoftheheartsize
• lateral:bettervisualizationofretrocardiacspaceandthoracicspine(moresensitiveatpickinguppleural
effusions)
■ helps localize lesions when combined with PA view
• AP:forbedriddenpatients(generallyalowerqualityfilmthanPAbecauseofenlargedcardiac silhouette)
• lateraldecubitus:toassessforpleuraleffusionandpneumothoraxinbedriddenpatients;however, POCUS can also be utilized for both of these purposes
• lordotic:angledbeamallowingbettervisualizationofapicesnormallyobscuredbytheclaviclesand anterior ribs
Film
Posterior-anterior Position
Figure 1. CXR views
Approach to CXR
Basics
Lateral Position
Anterior-posterior Position
Lateral Decubitus Position
Lordotic Position
• ID:patientname,MRN,sex,age
• dateofexam
• markers:rightand/orleft
• technique:view(e.g.PA,AP,lateral),supineorerect • indicationsforthestudy
• comparison:dateofpreviousstudyforcomparison(ifavailable)
• qualityoffilm:inspiration(6thanteriorand10thposteriorribsshouldbevisible),penetration(thoracic
spine should be visible) and rotation (clavicles vs. spinous process)
©Bonnie Tang 2012