Skeletal Flashcards

1
Q

Workhorse radiotracer?

A

Methylene diphosphonate (MDP) tagged with Tc-99m

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2
Q

How do you make MDP - Tc99m?

A

MDP + Stannous (tin) ion in a kid, add pertechnetate and stannous ion reduces it to bind MDP.

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3
Q

What happens if there isn’t enough stannous ion in the kid to prepare MDP - Tc99m? (or air gets in the vial causing oxidation?) Where will this product accumulate in your study?

A

Results in free Tc that can accumulate in the salivary glands, thyroid gland, and stomach.

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4
Q

How long do you wait to image after injection of MDP - Tc99m to image? Why?

A

2-4 hours to clear the soft tissues and visualize bones

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5
Q

What is the mechanism of uptake of MDP - Tc99m?

A

Chemisorption - phosphonate binding to bone

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6
Q

What is distribution of MDP - Tc99m based off of?

A

Osteoblastic activity and blood flow

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7
Q

Study is blurry, fuzzy, with bone and kidney uptake, what tracer?

A

MDP - Tc99m

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8
Q

Study is “high-res” and looks like a MIP-PET, what tracer?

A

F-18

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9
Q

Study looks similar to F-18 but has brain uptake, what tracer?

A

FDG-PET with bone stimulation

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10
Q

What organ receives the highest dose with MDP-Tc99m? F-18? Overall dose higher with?

A

Bone
Bladder
overall dose > with F-18

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11
Q

Why can pyre lytic lesions be cold with MDP - Tc99m?

A

Uptake based off of blastic activity

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12
Q

Where is MDP - Tc99m uptake normal?

A

Bone, Kidney (not seen or very faint = Super Scan), Bladder, Breasts (young women), soft tissues (low levels), epiphyses of kids

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13
Q

Marked uptake in skull sutures?

A

Renal Ostreodystrophy

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14
Q

Focal breast uptake? (asymmetric breast uptake)

A

can be cancer, diffuse normal in young women

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15
Q

Renal cortex activity?

A

If hotter than lumbar spine, think hemochromatosis

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16
Q

Diffuse renal uptake?

A

Setting of chemotherapy +/- urinary obstruction

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17
Q

Liver Uptake? 4 reasons

A

Too much Al+3 contamination of Tc
Cancer - Hepatoma or mets
Amyloidosis
Liver Necrosis

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18
Q

Spleen uptake?

A

Auto-infarcted spleen (sickle cell) - will have scattered hot and cold bone from multiple bone infarcts

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19
Q

Lung uptake?

A

Most cases - heterotopic calcification
Classic MDP hot lung met = osteosarcoma
Ultimately not specific

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20
Q

Single lesion is usually a false positive bone met except where?

A

Single sternal lesion in breast cancer patient

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21
Q

Sacral insufficiency fracture sign?

A

Honda sign

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22
Q

Diffusely decreased skeletal uptake?

A

Free Tc or bisphos therapy

23
Q

Wait how long before dx fracture in elderly?

A

1 week

24
Q

Horizontal linear vertebral body fracture? What happens on follow up images?

A

osteoporotic fracture, f/u imaging shows decreasing tracer uptake

25
Q

Extension of vertebral body fracture into posterior elements or involves pedicles?

A

Cancer - malignant fracture

26
Q

What is the flair phenomenon and how do you tell if it is the flair phenomenon?

A

Good response to therapy looks like bad response and increased radiotracer uptake (size and #) is seen 2wks - 3 mo after therapy

On plain films lesions get more sclerotic and improve after 3 months for flair

27
Q

What radiotracers are superior for detection of neuroblastoma bone mets? Where does NB like to met to in the bones?

A

I-123 and 131 MIBG, metaphysis

28
Q

6 Cold Lesions on bone scans?

A
Radiation therapy
Early osteonecrosis
Infarct (early or late)
Anaplastic tumor ( renal, thyroid, Neuroblastoma, myeloma)
Artifact from prosthetic, pacemaker
Hemangioma
29
Q

4 characteristics of Bone Island and prostate Met?

A

BOTH Sclerotic
Prostate met should be VERY hot
Bone Island should be COLD
Osteopoikilosis should be COLD

30
Q

Bone scan better for lytic/blastic mets?

Skeletal survey better for lytic/blastic mets?

A

Bone scan better for blastic

Skeletal survery better for lytic - think MM

31
Q

Why image Heterotopic Ossification?

A

To see if it’s active/mature. If active has a higher rate of recurrence after resection.

32
Q

Characteristic finding: Tramline along the periosteum of long bones. What is this process associated with? What do you need to think of and recommend?

A

Heterotrophic Osteoarthropathy
Ass. with chronic hypoxia (COPD, Cyanotic Hrt Dz, Mesotheliomia, Pneumoconiosis)
Need to think lung cancer - 10% of the time - Get CXR/CT

33
Q

5 Ways Paget’s is classically shown?

A

1) Super hot enlarged femur
2) Super hot enlarged pelvis
3) Super hot skull
4) Expanded hot entire vertebral body
5) metabolic superscan (however, if shown a metabolic superscan think Hyper PTH)

34
Q

Imaging findings of AVN?

A

Early - Cold
Middle - Hot
Late - Cold

35
Q

Ewings and Osteosarcoma will be? Why scan?

A

Hot, see extent of dz

36
Q

Double density sign (central hotter nidus within a hot area) seen with?

A

Osteoid Osteoma

37
Q

Super hot mandible?

A

Fibrous dysplasia - can also be leg that looks similar to paget

38
Q

Benign HOT Bone scan lesions? (5)

A
Fibrous Dysplasia
Giant Cell Tumor
ABC
Osteoblastoma
Osteoid Osteoma
39
Q

Benign COLD Bone scan lesions? (1)

A

Bone cyst without fracture

40
Q

Variable benign lesions? (2)

A

Hemangioma

Multiple hereditary exostosis

41
Q

Two types of super scans? How can you tell them apart?

A

Diffuse Mets - breast and prostate most common - and Metabolic - hyper Parathyroid, renal OD, peget, thyrotoxicosis (no kidneys seen on super scans). Skull is asymmetrically hot on metabolic.

42
Q

Any uptake from bone with MIBG, I131, or octreotide should mean what?

A

METS!

43
Q

Equivocal bone lesion next steps?

A

Recommend plain film, if plain film shows no corresponding lesion it is MORE concerning for mets –> get MRI at that point

44
Q

3 phases of a 3 phase bone scan?

A

Flow, Pool, Delayed; lots can be hot on all 3 phases

45
Q

Difference between cellulitis and osteomyelitis on 3 phase scan?

A

Cellulitis hot during flow and pool, not delayed

Osteomyelitis hot during all 3

46
Q

How to use 3 phase to evaluate treatment response?

A

Blood flow and blood pool stay abnormal for 2 months, and delay persists for 2 years. Use Ga67 and I111 WBC for monitoring response.

47
Q

Where do you see uptake in RSD? (Complex Regional Pain Syndrome)

A

Increased uptake on flow and blood pool, with periarticular uptake on delayed phase.

48
Q

Tc tagged with what to localize bone marrow? What is the major utility?

A

Sulfur colloid, use in sickle cell. Major utility is to use with tagged WBC or Gallium to evaluate active infection.

49
Q

When is a combined Tc-Sulfur Colloid + WBC study positive for infection?

A

Activity on WBC image, without corrresponding Tc-Sulfur colloid activity on bone marrow image.(except in spine!!)

50
Q

What is special about imaging infection within the spine?

A

WBC fails to migrate showing a photopenic area, use gallium instead.

51
Q

How to evaluate a prosthetic?

A

Look for loosening/infection, more helpful when negative - scan with combined Tc-sulfur colloid + WBC

52
Q

How to evaluate a neuropathic foot?

A

Use combined marrow + WBC because difficult to distinguish arthritis vs infection with Tc MDP

53
Q

What is the “fourth phase” of diabetic foot evaluation?

A

24 hour scan due to reduced peripheral blood flow

54
Q

2 reasons to consider T99 HMPAO instead of In-WBC for infection? Why not all the time?

A

Kids - lower absorbed dose and imaging time
Small parts - better in hands and feet
Short halkf life and normal GI and gallbladder activity