THE SKELETAL SYSTEM

MUDr.Kateřina Táborská

Bone scintigraphy

Bone physiology and skeletal anatomy

balance osteogenesis bone resorption osteoblasts osteoclasts

The response of bone to injury or disease ↓

reactive bone formation

Radiopharmaceuticals:

99mTc – diphosphonates ( MDP –methylene diphosphonate)

Concentration predominantly in the mineral phase of bone (crystalline hydroxyapatite and amorphous calcium phosphate) iv.distributed via blood flow throughout the bodypassively diffused into the extravascular and extracelular spacesbinding to the hydration shell around the bone crystalunbound radiotracer clears from the plasma via urinary excretion

Uptake of RF depends on:

1. blood flow

flow must be present for delivery

increased blood flow increased deposition

2. metabolic bone activity

bony turnover

osteoblastic lesions growth centers

Patient preparation:

good hydration

to urinate immediately prior imaging

Contraindiaction:

pregnancy

Two types of bone scans:

Standart bone scan:

iv., imaging of the entire skeleton, 2-5 h

Three-phase bone scan:

1. Phase – angiographic

rapid sequence flow images of the area of interest (60 x 1 sec.)2. Phase (blood pool, soft tissue uptake)

ten minut delayed static images3. Phase (bone)

delayed images of the region in question, 2-5 h

3F bone scan

whole body bone scintigraphy

Bone SPECT

Bone SPECT – improved sensitivity greater anatomic details

3D rekonstrukce sagitální

koronální

transaxiální

I. 3D rekonstrukce II. tomographic slices

Static images

Static images with pinhole collimator

ANT

pinhole

Normal scan: axial and appendicular skeleton

Symetry, the bones with minimal soft-tissue activity

Both kidneys with mild activity, urinary bladder

Normal scan: children

increased uptake in growth centers

margins of growth plate clearly demarcated

Areas :increased uptake 95 - 98% (fracture, osteomyelitis, neoplasia, arthritis)decreased uptake (lytic lesions, early necrosis)

Abnormal scan

Abnormal scansuperscan

Diffuse symetrical increased uptakeLack of kidney activity

Soft tissue or extra-osseous uptake

inflammation, calcification, muscle or tumor necrosis, myositis

neuroblastoma rhabdomyolysis

hydronephrosis

hydroureter

excretion via genitourinary tract

nefrocalcinosis

INDICATIONS

1. metastatic disease

2. primary malignant bone tumors

3. benign primary tumors

4. osteomyelitis

5. fracture

6. avascular necrosis

7. metabolic bone disease

METASTATIC DISEASE

Tumors most likely to metastasize to bone:

breast

prostate

lung

lymphoma

thyroid

renal

neuroblastoma

METASTATIC DISEASE

more sensitive than plain RTG, 30-50% of bone mineral must be lost before a lesion can be detected

surveying of the entire skeleton

Approximately 90% of metastases are multiple

initial staging

follow up

diffuse bone pain

laboratory findings (PSA)

Prostate cancer

METASTATIC DISEASE

flare fenomen

3-6 mo after chemotherapy, hormonal therapy

increased uptake in known lesions and even new foci may be seen because of a healing response

serial scanning

PRIMARY MALIGNANT BONE TUMORS

Osteosarcoma

Ewing‘s sarcoma

3F bone scan

WB - skip lesions and metastatic foci

Osteosarcoma

19-year old man with pain of right knee, the initial staging

Ewing‘s sarcoma

17-year old man with pain of left knee, the initial staging

Osteosarcoma of left tibiaPersistent increased uptake at the treatment site 6-12 mo after therapy, compared with a postherapy baseline, is considered suspicious for local recurrence

21-year old man after chemotherapy and amputation

usually normal uptake bone cysts bone islands fibrous cortical defects

osteiod osteoma negative scan virtually rules out

BENIGN PRIMARY TUMORS

16-years old girl with aching pain, worse at night, relieved with aspirin and exercise at right

OSTEOMYELITIS

3-phase bone scintigraphy

flow – increased

blood pool – increased

delayed – increased

dif.dg. cellulitis – increased only flow and blood pool

high sensitive on unaffected bones

positive during 24-48 h

X-rays normal for first 10-14 days

1.phase 2.phase 3.phase

Osteomyelitis (left calcaneous)1.phase (curve from the region of interest - ROI)

multifocal osteomyelitis

13-year old girl with OM of left clavicule

6-year old boy with pain of left thigh

1.phase 2.phase 3.phase

1.phase

Myofasciitis of left thigh

FRACTURE

TRAUMATICwill become positive within 24 h 90% normal by 2 yearstu pick up old fractures such as in spinechild abuse

STRESS a) fatigue – caused by repeated abnormal stress on normal bone - runnersb) insufficiency – resulting from normal stress on abnormal bone (osteoporosis, postirradiation)

polytrauma

27-year old woman after car crash

13-year old boy after fall from tree

Fracture of Th 8

Stress fracture of left tibia

17-year old girl with painful left leg after training for an athletic event

ANT anterior lateral

pinhole collimator

AVASCULAR NECROSIS

Adults – as a result of fracture, metabolic disorder, steroids, hemolytic anemias, vasculitis

Children: Legg-Calve- Perthes disease

early: decreased activity

followed by increasing activity if subsequent revascularisation and healing occur

Morbus Perthes l. sin.

normal early phase

5-year old boy with hip pain

METABOLIC BONE DISEASE

OSTEOPOROSISOSTEOMALACIAHYPERPARATHYROIDISM (primary, secondary)

superscan or complication: pseudofracture,compresive fracture

PAGET‘S DISEASEincreased resorption of bone accompanied by increase in bone formationnewly formed bone is abnormally soft increased uptake due to significant increase in blood flow

PAGET‘S DISEASE

ADVANTAGES

high sensitivity

early changes

ability to survey the entire skeleton without added radiation (5 mSv)

DISADVANTAGES

lack of specificity

A specific diagnosis often can be made when the bone scan is correlated with other imaging

(plain films, CT)