Imaging modalities Flashcards
limitations of 2D mammo
-summation artifact/superimposed tissue
-malignancies can be hidden in glandular structure
-false positive/false negative
Digital breast tomosynthesis (DBT)
-images are perpendicular to beam
-images are parallel to detector (stacked)
-projections are reconstructed into slices
-slices are dependent on breast thickness
sweep of gantry (Arc)
-set by vendor
-hologic and fuji: 15 degree sweep (standard mode)
-GE: 25 degree sweep
-siemens: 50 degree sweep
projections
-angles in degrees from the negative to positive side
-these are the images initially taken
-this is where the actual radiation dose to the pt comes from
slices
-number of images created from projections to create the 3D mammo
-dependent on how much the breast is compressed in millimeters
-slices created from projections
-1 mm thick slices
for CC DBT image set taken from
inferior to superior breast (breast side closest to detector)
for MLO DBT image set taken from
lateral to medial breast (breast side closest to detector)
DBT radiation dose
-each projection is a small fraction of the total dose
-DBT: 1.81 mGy one view
-MQSA: 3 mGy per view
synthesized view (2D synthetic)
-must have an approved form of 2D images to be read with 3D images
-uses only 3D slices to create synthetic 2D images
-no added dose to pt, cut down dose in half, better visual of details
2D synthetic view
-images must include a mark to alert users that images are not FFDM images
-hologic: C-view/intelligent 2D
-GE: V-preview
-siemens: insight 2D
-fuji: S-view
what are the indications for breast ultrasound?
-screening breast US
-abnormal mammo
-diagnostic exams (callbacks)
-clinical symptoms: palpable, pain, breast changes
-guidance for intervention
-second look after MRI
how does glandular dense tissue appear on mammogram and ultrasound?
appears brighter (white)
Whole breast ultrasound (WBUS) / Automated whole-breast ultrasound (ABUS)
-adjunct screening exam (for asymptomatic and dense breast tissue)
-automatically scans woman’s breast capturing multiple images
-displays them in 3D for radiologist review
-not operator dependent
Malignancies on MRI
-use gadolinium as contrast
-malignancies can have hypervascularity and enhance
-it can also cause benign vascular lesions to enhance (lymph node)
breast MRI indications
-new cancer staging
-implants
-nipple discharge
-eval of scarring
-problem solving post surgery
-monitoring of neoadjuvant chemotherapy
-searching for primary tumor
-searching for high risk pt
breast MRI pitfalls & precautions
-only effective in 50% of pts w/ DCIS but very effective in pt with dense breasts and implants
-high sensitivity, low specificity
-US re-eval. necessary
What is the lymphatic system?
network of lymph nodes to rid the body of toxins, waste, and other unwanted material
what does the lymphatic system do?
continually collect excess interstitial fluid and drain it away from the tissue
what happens without the lymphatic system?
-lymphedema: tissue swelling from an accumulation of fluid that is unable to drain through the lymph system
sentinel node mapping
-check for breast cancer cells spreading (metastasizing)
-the first lymph node that drains lymph from specific area of body (usually axillary chain)
-reduce the number of lymph nodes needing to be removed (axillary dissection; removal of Level 1 & 2 nodes)
sentinel node procedure
-radioactive isotopes and/or blue dye is injected at the site of the lesion (2 hrs before surgery)
-gamma detector (in surgery) is used to locate path of drainage from the tumor to the sentinel lymph nodes (1-5 sentinel nodes possible)
-can be testing immediately or after procedure (if neg, no need to remove more. if pos, may need to remove more nodes, which causes lymphadenopathy)
