Diseases, Treatments, and Imaging Pitfalls Flashcards
Autoimmune and cancer
Most often dealt with by medical physicists
Examples of autoimmune diseases
Rheumatoid arthritis (joints), Systemic Lupus Erythematosus (vasculitis), Crohn’s Disease (small bowel/colon), Diffuse Toxic Goiter (thyroid), Psoriasis (skin), Aplastic anemia (blood cell lines)
Diffuse Toxic Goiter (Grave’s Disease)
T- and B-cells produce antibodies to the TSH receptor, stimulates uptake of iodine, growth of thyroid follicles and production of thyroid hormone (hyperthyroidism). “Goiter” refers to a chronic enlargement of the thyroid gland.
Symptoms of Hyperthyroidism
Weight loss with normal appetite, Nervousness / irritability / sleeplessness, Heat intolerance / sweating, Tremors, Diarrhea, Menstrual abnormalities, Palpitations (irregular heartbeat)
Exophthalmos
Can be a complication of hyperthyroidism. Eye bulges out of socket.
Treatment of Toxic Goiter
Drugs (propylthiouracil) and beta blockers (short-term), Ablation with radioactive iodine
Characteristics of Cancer
Dedifferentiation, Neovascularity (independent vessel generation), Invasiveness, Metastasis
Carcinoma vs Sarcoma vs Lymphoma
Cancer of epithelial tissues like glands and skins vs cancer of bone and soft tissues vs Cancer of lymphatic tissue
Glioma vs Neuroendocrine tumor
Tumor of glial (supporting brain) cells vs Actual cancer of the neurons from embryo
TNM System for Cancer Classification
T: extent of tumor, N: lymph node involvement, M: metastasis. Brain and blood do not have TNM designation.
Stage System for cancer classification (defunct)
0 - very localized cancer, IV - completely metastatic
T Designations for Cancer
TX - cannot be evaluated, T0 - no primary tumor, Tis - non-invasive carcinoma, and T1~4 for size and extent of primary tumor
“Summary Staging” for cancer classification
In situ, localized (contained within the organ), regional (spread to nearby organs), and distant (spread far)
RECIST
Response Evaluation Criteria In Solid Tumors is an imaging-based method for quantifying the changes in solid tumor size and other parameters in response to radiation or drug therapy. Graded as Complete Response, Partial Response, Stable Disease or Progressive Disease.
Breast cancer therapy
Characterized by microcalcifications. Treatments include lumpectomy (cutting away small lumps to preserve breast), mastectomy + lymph node dissection, LINAC/IMRT, brachytherapy (introducing radioisotopes to body), and chemotherapy like estrogen receptor blockers
Cervical cancer therapy
Therapy options include surgery (hysterectomy: removal of uterus), brachytherapy, external beam therapy for invasive disease. Isotopes include cesium-137 and Iridium-192 (74 days).
Lung cancer therapy
Treatments include surgery (lobectomy, wedge resection, pneumonectomy), external beam, chemotherapy if metastatic
Prostate cancer therapy
Symptoms of prostate cancer include frequency of urination and difficulty in urination. Blood Prostate Specific Antigen is high. Treatments include resection of prostate, cryosurgery (freezing), external beam, radioactive implants (brachytherapy, includes iodine-125 or palladium-103)
Brain tumor therapy
Resection, chemotherapy, gamma knife, brachytherapy
Thyroid cancer therapy
2:1 female-male ratio. Tc-99m pertechnetate scintigraphy can identify this cancer. Total body diagnostic I-131 scan to identify metastasis and kill.
Hodgkin’s Disease (Lymphoma)
Characterized by enlarged lymph glands near neck, groin. Treated with external beam radiation therapy, great prognosis
Non-Hodgkin’s Lymphoma
About 200 / 100,000 per year in U.S (7 – 8 times more common than Hodgkin’s Disease), diffuse disease involving lymph nodes and bone marrow. T-cell and B-cell types. Gallium-67 citrate scintigraphy and PET with F18-FDG. Immunotherapy with monoclonal antibodies against B-cells (MAB); radioimmunotherapy: I-131 MAB or Y-90 MAB
Intraocular Melanoma
Cancer of the eye, can be treated with enucleation (eye removal). Radiation therapy can be an effective treatment that preserves vision and the eye. Episcleral plaque therapy (disk of radioactive substance attached near eye) with Iodine-125 or Palladium-103.
Organomegaly
Due to outlet obstruction, tissue hypertrophy. Splenic hypertrophy can be caused by sickle cell anemia or portal vein obstruction.
Replacement
Primary tumors can replace normal tissue with neoplastic processes. Hepatic steatosis (“fatty liver”) is an example of non-tumor replacement.
Benign vs metastatic on radiographs/CT
For benign, regularly shaped and encapsulated, calcification is extensive; for metastatic, irregular shape and spread out, invasion of nearby tissues, calcification is sporadic
Types of abnormal gas or liquid collection
Gas: pneumothorax, pneumomediastinum, bacterial overgrowth, dead tissues; Liquid: internal bleeding, obstruction, ascites (fluid in abdomen), inflammation, cysts
Streaking artifact on CT
Metal or other hard substances cause this artifact
Ferromagnetic material on MRI
Can cause dark bands, if magnet causes the slice to be outside of slice selection.
Movement during MRI
Can cause multiple images of the body to smear across
Movement during CT
Can cause parts of the screen to look like it’s “breaking off”
Variant Anatomy
When body naturally has different stuff than normal, like extra bone, etc.
