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​Skeletal System Review

94/111 =85%

  1. Describe, in detail, how bone agents are localized.3

Delivered by intravenous injection, the radiopharmaceutical travels through the blood to the bones where the radioactive phosphorous found in the diphonsphonate exchages with calcium .....heteroionic exchange. (2/3)


Accumulation of the radiopharmaceutical is related to the exchange of phosphorus onto the calcium of hydroxyapatite. Radiopharmaceutical is thought to bind to bone by chemisorption.

  1. Give 4 reasons why there could be increased activity on a bone scan. (NOT A PATHOLOGY) 4 GOOD

~Epiphyseal plates in children show increased uptake
~Areas where tendons insert and chronic stress will show increased activity
~Ureters and bladder will show an increased uptake
~The Nasopharynx area will show an increased uptake


  • What is a “Superscan”? 3

A super scan is a bone scan that shows little or no kidney activity, increased uptake to all of the bones as a result of chronic renal disease, endocrine disorders, recent treatment, etc. (1/3)
    1. What is the “glove phenomenon”? 2
The glove phenomenon is when there is increased activitiy in soft tissue distal to the site of injection due to to arterial injection of the radiopharmaceutical. Good
    1. What is a “cold spot”? 2
A cold spot is where there is decreased uptake of the radiopharmaceutical relative to the normal. Good
    1. Describe how bone agents are removed from the body. How is this implicated in pt prep? 5

Bone agents (radiopharmaceutical) are removed from the body through the urine. The radiopharmaceutical travels through the urinary system and must be excreted. This is implicated in pateinet preparation by letting the patient know that they should consume a lot of fluid and frequently void as well as fully empty their bladder prior to having images taken. Eliminated by the kidneys (4/5)

    1. There are 2 commonly used bone-imaging agents. How are they similar and what does this have to do with the bone uptake? 3

99m-Tc methylene diphosphate(MDP) and 99m-Tc hydroxymethylene diphosphate (HDP), they both exchange phosphorus onto the calcium hydroxyapatite of the bone ( this is called heterionic exchange) by chemisorption. The hydroeyapatite crystal builds up based on blood supply, if there is a diseases the capillaries are more permeable and more blood flow is to that area therefore there is more to bind to and the uptake will be more.

Both are diphosphonates, etc. See page 243-244 of Mettler (1/3)
    1. Describe the “flow technique”. 3

Flow technique allows us to see the blood flow of the area we are examining. The patient is positioned in the field of view on the camers and the Radiopharmacutical is injected ,with a tourniquet on the arm or ankle, on the imaging bed; the arm that is injected is raised so gravity can help with the blood flow and take off the tourniquet. Depending on the area being imaged the camera is started as soon as injection is done or after a count. The camera takes consecutive pictures (3-5sec per frame) to show the blood movement Good
(3/3)
    1. List what views you would do for an articular scan. 4
spot views of palmer views, plantar views, hips, elbows (all the joints) and a whole body. Good

    1. Calculate the SI Joint Ratio with the following information, and “interpret” the results. 3
· Left SI=863
· Right SI=987
· Sacrum=800
863 = 1.08 987 = 1.23 range -- 1.08 : 1.23
800 800
the normal range for a SI joints is 0.94--1.34 the ratio calculated is within this range and is therefore normal
Good
    1. Why would you do a “caudal view” on a bone scan? 2
Caudal view is important when imaging for pelvic fractures or lesions (sacrum, coccyx) Good

    1. Once 1 bone picture is done, why are all the others done for the same amount of time, rather than counts? 2
It depends on the area being imaged and is predetermined number of counts But why?? Images will be of uniform intensity, thereby allowing different views to be compared (0/2)

    1. List 8 biological factors affecting image quality. 8
state of hydration
Renal function
obesity
patients age
Medication - Steroids, therapeutic agents
Radiation Treatment
Contract Media
Metallic Devices
-how is a metallic device a BIOLOGICAL factor?? (7/8)
    1. List 5 technical factors that affect image quality. 5
Time interval between imaging and injection
Ratio of bone or blood to soft tissue activity
-how is this a technical factor???
Distance of structure being imaged from camera
Imaging system Quality control
Radiopharmaceutical
what....
(3/5)
    1. Name 3 pathological conditions make is it essential to image long bones? 3
Osteomyletics
Cellulitis
Osteoporosis

None of the above (0/3)
Arthritis, Fibromyalgia, Lung cancer-any type, Renal cancer-any type

    1. Describe the distribution of bone metastases. 3
Bone metastases are mostly found throughout the axial skeleton, there are blotchy hot spots throughout the thorax, ribs, spine, and pelvis the term "lit up like a christmas tree" is a term commonly used to describe an extreme case of bone mets. multiple focal hot spots (2/3)
    1. Ewing’s sarcoma patients do not have + bone flows. Why? 2 Has Elvis left the building....???
      (2/2)

    1. What is the difference between cellulitis and osteomyelitis? What about the images? 8 Cellulitis is a bacterial infection affecting the skin and the underlying tissues, osteomyelitis is a bacterial infection of the bone and bone marrow. When osteomylitis is is question a 3 phase bone scan is used, the two may look alike in the flow and pool but cellulitis will show normal bone uptake on the delay and the bone to soft tissue ratio falls vs the osteomylitis which will show increased uptake on the delay and he bone to soft tissue ratio will increase up to 24 hours later. Good
    2. How soon after a # before you get a + bone scan? 1
2-4 hours after injection # means a fracture. How soon after a fracture will a bone scan be positive? (0/1)
95% at 24 hours, 100% at 72 hours
    1. What is the RES and where is it found? 6
RES is reticuloendothelial system, it is found in the reticular connective tissue which is mostly in the spleen, liver, bone marrow, lymph nodes and alveoli. Good
    1. Where is normal bone marrow found? (Adults and children and why) 10

In adults, normal bone marrow is primarily found in the axial skeleton, vertebral bodies, sternum, ribs and skull and in the appendicular skeleton, it is found in the pelvis, scapulae and proximal humeri and femora. In children, normal bone marrow is more distally situated occupying the entire extremities in newborns, but by the age of 10, children exhibit adult pattern for normal bone marrow. Bone marrow is found in these places because children are still growing and also have different blood volumes then adults, therefore, bone marrow doesn’t extend all throughout their bodies. Children’s immunity is different than an adult which also contributes to the different locations of bone marrow. Proximal 1/3 Good (9.5/10)
    1. What radiopharmaceutical is used for a bone marrow study and why? 3

99mTc sulfur colloid is used for a bone marrow study, which localizes in marrow because the particles are phagocytized by the resident reticuloendotheilial cells in the marrow. Good
    1. What is the mechanism for localization? 3

The mechanism for localization is compartmental localization, but also phagocytosis. The phagocytic cells engulf and destroy particulate materials or materials that they recognize as “foreign”. Monocytes and macrophages in the reticuloendothelial system (RES) phagocytize foreign substances from the body. The RES would be the “compartment” and all the radiocolloid particles are located in these areas. Good
    1. Why is the evaluation of extramedullary hematopoeisis difficult with this test? 3

The extramedullary hematopoiesis is difficult to evaluate because the normal uptake of sulfur colloid by the liver and spleen can interfere when imaging structures in that area, therefore, the extramedullary hematopoiesis being in that area would be hard to image. Good
    1. Why is a bone marrow scan better than a bone scan for the evaluation of multiple myeloma? 2

Bone marrow scanning is more sensitive for multiple myeloma because metastases hit the bone marrow before it hits the bone itself, therefore, in a bone scan it would show up as normal or just less uptake, but a bone marrow image would be able to detect it better. Multiple myeloma is a primary bone cancer and aren't evaluating mets...yet. (1.5/2)


What is the purpose of a bone densitometry? 1
The purpose of bone densitometry is to asses how thick(dense) a patients bones are and to determine if they are normal, osteopenic or osteoporotic. Good
List 4 factors that determine bone mass. 4
Four factors that determine bone mass are: genetics , mechanics, nutrition and hormones
Also the remodeling rate of bones also is a factor in determining bone mass.
Good
List 5 general indications for doing a bone densitometry scan.5
Five possible indications for doing a bone densitometry scan would be
Premenopausal oophorectomy, premature menopause or estrogen deficient conditions like amenorrhea.
Long-term corticosteroid use
Unexplained fractures.
When x-rays question osteopenia.
Endocrine disorders. (for example prolactinoma, hyperthyroidism)
Good

Why are the pt’s age, sex, height, weight, and ethnicity important? 3
These factors are important because they have an effect on what is normal and abnormal for density. For example a young person has bones that are more dense than an older person. Also a females bones become less dense over time more so than a man. As well, a Chinese person’s bones are less dense than a Caucasians bones, who’s bones are less dense then that of a black person’s.
Allows us to determine "normal results" for each category so the correct database is used (2.5/3)

How do you position patients for both images? Be specific. 6
For both images the patient is lying in a supine position (belly up).
For the lumbar spine the legs must be elevated on a block ( this flattens the normal curve of the lumbar spine) The patients back should be flat against the bed with the legs at a 45° angle. The spine must be centered in the image the top half of L5 must be in the image and continue up until the ribs are visualized . L1 to L4 are the most important.
For the femur image the shaft of the femur is perpendicular to the scan path. The leg should be rotated inwards so that the lesser trochanter can’t be seen. There must be soft tissue in all four coners of the neck ROI. In order to ensure this your acquisition should begin 2-3 sweeps before the ischium and 2-3 sweeps after the greater trochanter.


T-12 must be seen in the spinal view
Good (5.5/6)

What can you determine from the bone density images? 1
Bone density images are not for interpretation. The data is what we use to interpret and determine what is normal or abnormal about the patient. Good
      • If a patient has a possible scaphoid #, what would you do?
      • If a patient has distal, suspected medial tibial #, what would you do?
      • If a patient has a suspected osteochondral #, what would you do?