SP6:Skeletal System Scintigraphy Flashcards
Which of the following is a malignant bone disease?
(a)Paget’s disease
(b) Ewing’s sarcoma
(c) Osteomyelitis
(d) Osteoid osteoma
(b) Ewing’s sarcoma is a type of cancer most often found in children and young adults and is more common in males than females. Paget’s disease is a chronic bone disease involving enlarged and deformed bones. Osteomyelitis is an infection of the bone or bone marrow. Osteoid osteoma is a benign bone tumor that is common in the appendicular skeleton. Osteoid osteoma demonstrates tracer uptake on blood pool images during a bone scan as opposed to most benign osseous neoplasms.
A three-phase bone scan is often done to differentiate
(a)Osteoporosis vs. cellulitis
(b) Osteomyelitis vs. diskitis
(c) Osteomyelitis vs. cellulitis
(d) Osteoporosis vs. septic arthritis
(c) Cellulitis often demonstrates as diffuse increased activity on early images, and activity decreases on delayed images. Osteomyelitis shows increased uptake in bone on early images which continues to increase on delayed images.
The presence of gastric and thyroid activity on a bone scan signals the presence of:
(a)Metastatic disease
(b) Free pertechnetate
(c) Radionuclide impurity
(d) Reducing agent
(b) Free pertechnetate may be due to poor tagging of phosphates, or too much time may have elapsed between radiopharmaceutical preparation and injection.
What is the purpose of a reducing agent in a 99mTc diphosphonate kit?
(a)To oxidize technetium
(b) To lower the valence state of technetium
(c) To improve the tag efficiency
(d) Both (b) and (c)
(e) (a), (b), and (c)
(d) Stannous chloride reduces the valence state of technetium, thereby improving the tag efficiency.
What is the dose of 99mTc MDP most often prescribed for a planar bone scan?
(a)1–3 mCi
(b) 5–10 mCi
(c) 20–30 mCi
(d) 30–35 mCi
(c) Planar bone scans can be performed using 10-30 mCi of 99mTc phosphates and phosphonates; higher doses may be indicated in obese patients and calculated based on weight (300-350 uCi/kg).
Which of the following is least likely to cause an artifact on bone scan?
(a)Snap on trousers
(b) Colostomy bag
(c) Skin contaminated by urine
(d) Injection site
(b) Since most of the injected dose will leave the body via the urinary tract, the skin contaminated by urine is a common problem. Metal on clothing will cause an attenuation artifact. If there is even a small amount of extravasation of the dose during injection, there will be a hot artifact at the injection site. A colostomy bag is the least likely to cause an artifact on bone scans.
What is not an indication for a bone scan?
(a)Metastatic disease
(b) Osteoporosis
(c) Cellulitis
(d) Avascular necrosis
(b) Bone mineral density, which is decreased in osteoporosis, can be evaluated using quantitative CT (QCT), dual photon absorptiometry (DPA), and dual x-ray absorptiometry (DXA). Detection and follow-up of metastases and differentiation of osteomyelitis and cellulitis are common indications for bone scanning. It is also used for evaluating avascular necrosis.
The presence of free pertechnetate on a bone scan may be the result of:
(a)The use of a radiopharmaceutical which was prepared too long ago
(b) Introduction of air into the kit vial while adding technetium
(c) Increased blood flow to bones
(d) Both (a) and (b)
(e) (a), (b), and (c)
(d) Free pertechnetate demonstrate as gastric, salivary, and thyroid activity on bone scans may be the result of administering a dose form a kit that has been prepared more than 4 h prior to injection. Additionally, if air has been introduced into the reaction vial during labeling, there may be a poor technetium-phosphate tag.
What is the purpose of hydration and voiding after an injection for a bone scan?
(a)To block the uptake of unlabeled technetium by the stomach
(b) To reduce the possibility of urine contamination
(c) To obtain a superscan
(d) To reduce the radiation dose to the bladder
(d) Hydration and frequent voiding after administration of a diphosphonate radiopharmaceutical reduce the radiation dose to the bladder since the radiopharmaceuticals are excreted through the urinary bladder. Patients should void immediately before imaging so that bladder activity does not obscure visualization of the pelvis.
What could be the cause of generalized, diffuse activity in the abdomen on a bone scan?
(a)Free pertechnetate
(b) Malignant ascites
(c) Pacemaker
(d) Bone cyst
(b) Malignant ascites may be seen as diffusely increased activity on bone scans. Malignant pleural effusion may be similarly seen in the chest.
What timing protocol best describes a four-phase bone scan?
(a)During injection, immediately following injection, 2-4 h, and 18-24 h
(b) During injection, 2-4 h, 24 h, and 48 h
(c) During injection, immediately following injection, 2-4 h, and 6 h
(d) None of the above
(a) The fourth phase of imaging is usually completed approximately 24 h following injection; therefore, choices (b) and (c) are incorrect. This protocol may be necessary in patients with renal failure because soft tissue activity may persist.
A focal hot spot near the left femur shows up on a bone scan. What is/are the best way/ways to proceed?
(a)Change to pinhole collimator and image.
(b) Perform SPECT imaging.
(c) Have the patient remove clothing of that area.
(d) Ask the patient to wash the skin in that area with soap and water
(e) (c) and (d).
(e) Focal hot spots on bone scans that appear to be in soft tissue, particularly on the medial aspect of the thighs, are often the result of radioactive contamination on clothing or skin from urine. Patients should remove clothing and wash the skin to remove the possible contamination.
A bone scan showing relatively uniformly increased skeletal uptake of radiopharmaceutical with almost absent renal and bladder activity is usually referred to as a:
(a)Flare phenomenon
(b) Superscan
(c) Renal failure
(d) Suprascan
(b) Decreased renal activity, together with diffusely increased bone uptake, especially in the axial skeleton, is often referred to as a superscan. This is most often seen where there is diffuse metastatic involvement in the skeleton but may also be due to certain metabolic conditions. The flare phenomenon refers to the apparent worsening of bone metastases in the months following chemotherapy, which is actually due to increased uptake resulting from healing. Patients in renal failure often show overall increased soft tissue uptake.
The glove phenomenon is usually the result of:
(a)Reactive arthritis
(b) Intravenous injection
(c) Antecubital injection
(d) Arterial injection
(e) Subcutaneous injection
(d) The glove phenomenon is markedly increased activity in the distal extremity and is due to an arterial injection.
What are common sites of bony metastasis?
(a)Pelvis
(b) Spine
(c) Ribs
(d) All of the above
(d) Prostate, lung, and breast cancers often metastasize to the bone, most commonly in the bones of the thorax, spine, and pelvis.
What is the purpose of a stannous ion in a diphosphonate kit?
(a)Acts as a reducing agent
(b) Acts as an oxidizing agent
(c) Provides a stabilizing force
(d) Maintains particle size
(a) 99mTc, following elution form an alumina column generator, exists primarily in the valence state +7. Stannous ions reduce the valence state, usually to +4, and this improves the tag efficiency.
