Imaging Flashcards
Reasons for Imaging in the Management of Cancer
Screening Making the diagnosis Staging Operative planning Response to treatment Follow-up
Types of Imaging in Cancer
Plain films CT scans Fluoroscopy Mammography SPECT scans PET scans MRI Ultrasound
What are X-rays good for?
Lungs
Kidney/gall stones
Bones
X-rays not good for
Soft tissues
Brain
What do x-rays rely on?
Differential absorption Air Fat Water Bone densities
Imaging for Bone Lesions
X-rays
CT scans
MRI
PET/CT
What are we looking at on x-rays for oncology imaging?
Nature of the bone matrix Interface of lesion & bone Cortex intact? What part of bone? Benign vs. malignant
Define Benign Bone Lesions
Well-defined
No cortical destruction
No periosteal reaction
What are CT scans best for evaluating?
Subtle bone changes
What are MRI scans best for evaluation of?
Soft-tissue & infiltrative marrow lesions
Define Latent Bone Lesions
Surrounded by reactive cortical rim
Define Active Bone Lesions
Easily discernible transition without reactive rim
Define Aggressive Bone Lesions
Broad infiltrating border
Define Fluoroscopy
Continuous X-rays used to obtain real time moving images of internal structures
Define CT Scan
X-rays taken in several planes are computer processed to show images in multiple slices: AP, lateral, sagittal, x-section & even as 3D images
Advantages of CT Scancs
Differentiate structures of close physical density
Eliminates superimposition of organs
Show calcified & hemorrhagic lesions
Show in multiple planes or even as a 3D image
Advantages of CT Scans in Neoplastic Disease
Very good in the abdomen for staging
Very good for evaluation of masses in the chest
Can do virtual colonoscopy
Most intracranial neoplasms are visible
Disadvantages of CT Scans
Risk of cancer
Contrast: allergic reactions, anaphylaxis, nephropathy
Expensive
Observer variation
Define Pancoast’s Tumor
Extension of tumor at apex of the lung involving C8, T1, T2 nerves & possible destruction of ribs
Presentation of Pancoast’s Tumor
Shoulder pain radiating in the ulnar direction
Virtual Colonoscopy
Done with CT Requires bowel prep No sedation needed Not as sensitive as colonoscopy Can't do biopsies
Mammography
Uses low energy X-rays to generate images
Abnormal Mammogram
Needs breast examination Further mammography for confirmation Ultrasound for better definition BIRAD classification MRI with gadolinium- implants very dense Needle/surgical biopsy may be recommended Tissue diagnosis key
What do nuclear scans measure?
Bone metabolism or remodeling
Nuclear Scans
Radio-isotope injected IV 3 hours later, the patient is scanned Provides 2D image Function test Half material goes to the bones Eliminated through the kidneys
Bone Scans
Show increased metabolic activity or increase blood flow
Assess activity or known lesions
Find unknown lesions
Overestimates lesions
MM cold scan until cortical disruption occurs
What does PET stand for?
Positron emission tomography
What can a PET be combined with?
CT
MRI
When are PET scans especially useful?
Lymphomas
Lung CA
PET Scans
Detects active, rapidly growing tumors
Higher grade malignancies detected more than benign processes
What does SPECT stand for?
Single Photon Emission Computer-Assisted Tomography
What is a SPECT scan good for?
Small spinal lesions
Osteoid osteoma
Osteoblastoma
How do MRI machines work?
Powerful magnets excite H+ protons to emit measurable electromagnetic radiation
Different MRI Techniques
Angiography
Functional MRI
Diffusion MRI
CSF dynamics
Disadvantages of MRIs
Expensive Slow Claustrophobia Pacemakers, stents Small metal fragments Metal artifact Need a calm patient May be genotoxic
MRI of the Spine
Radiation free
Superior for soft tissue imaging
Can see subtle differences
Gadolinium assists in delineating surrounding vascularity
Ultrasound
High frequency sound waves
Reflect & echo off of tissues
Processed in ultrasonic scanner
Usually seen as 2D image
Advantages of Ultrasound
Cheap, quick, easy, safe, comfortable
Shows solids, fluids, muscle, tendon, bone surface
Hampered by bone, air, fat
Disadvantage of Ultrasound
Operator dependent
When to Use Ultrasound
Thyroid tumors/lesions (test of choice)
Supplement mammography
How to make a cancer diagnosis?
Tissue: open biopsy or needle biopsy
Lung Biopsy Complications
Pneumothorax
Hemoptysis
Which cancers primarily metastasize to the bones?
Breast
Prostate
Lung
Kidney
Where are spine mets typically seen?
Base of pedicle
Unilateral destruction of pedicle “winking owl sign”
Define Pathologic Fractures
Occur through area of weakened bone: osteoporosis, benign cystic tumor, malignant tumor
PROs of X-ray
Simple
Inexpensive
Readily available
Easily interpreted
CONs of X-ray
Radiation
Poor tissue contrast
Technician dependent
2D
PROs of CT Scans
Rapid
3D capability
Axial imaging
Good bony detail
CONs of CT Scans
Highest radiation
Motion & metal artifact
Limited ST contrast
PROs of Bone Scans
Images metabolic activity
Very sensitive in bones
Low cost
CONs of Bone Scans
Non-specific
Poor detail
Anatomic changes not visualized
PRO of MRI
Superior tissue resolution
CONs of MRI
Expensive
Motion & metal artifact
Can’t use in some patients
PROs of PET/CT or MRI
Combines function & anatomy
Best for most cancers
CONs of PET/CT or MRI
Expensive (pre-auth)
PROs for Ultrasound
Very safe
Inexpensive
Quick
CONs for Ultrasound
Small field of view
Technician & radiologist dependent
Artifacts
