THE SKELETAL SYSTEM MUDr Kateina Tborsk Bone scintigraphy

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: 99 m. Tc – 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 body passively diffused into the extravascular and extracelular spaces binding to the hydration shell around the bone crystal unbound radiotracer clears from the plasma via urinary excretion

Uptake of RF depends on: 1. blood 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 images 3. Phase (bone) delayed images of the region in question, 2 -5 h

3 F bone scan

whole body bone scintigraphy

Bone SPECT

Bone SPECT – improved sensitivity greater anatomic details I. 3 D rekonstrukce II. tomographic slices transaxiální 3 D rekonstrukce sagitální koronální

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

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

Abnormal scan superscan Diffuse symetrical increased uptake Lack of kidney activity

Soft tissue or extra-osseous uptake inflammation, calcification, muscle or tumor necrosis, myositis neuroblastoma rhabdomyolysis

excretion via genitourinary tract hydronephrosis hydroureter nefrocalcinosis

INDICATIONS 1. 2. 3. 4. 5. 6. 7. metastatic disease primary malignant bone tumors benign primary tumors osteomyelitis fracture avascular necrosis 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 3 F 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 tibia Persistent 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

BENIGN PRIMARY TUMORS usually normal uptake bone cysts bone islands fibrous cortical defects osteiod osteoma negative scan virtually rules out 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 1. phase (curve from the region of interest - ROI) (left calcaneous)

multifocal osteomyelitis 13 -year old girl with OM of left clavicule

1. phase 2. phase 3. phase Myofasciitis of left thigh 1. phase 6 -year old boy with pain of left thigh

FRACTURE TRAUMATIC will become positive within 24 h 90% normal by 2 years tu pick up old fractures such as in spine child abuse STRESS a) fatigue – caused by repeated abnormal stress on normal bone - runners b) insufficiency – resulting from normal stress on abnormal bone (osteoporosis, postirradiation)

polytrauma 27 -year old woman after car crash

Fracture of Th 8 13 -year old boy after fall from tree

Stress fracture of left tibia pinhole collimator ANT anterior lateral 17 -year old girl with painful left leg after training for an athletic event

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 5 -year old boy with hip pain early phase

METABOLIC BONE DISEASE OSTEOPOROSIS OSTEOMALACIA HYPERPARATHYROIDISM (primary, secondary) superscan or complication: pseudofracture, compresive fracture PAGET‘S DISEASE increased resorption of bone accompanied by increase in bone formation newly 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 m. Sv)

DISADVANTAGES lack of specificity A specific diagnosis often can be made when the bone scan is correlated with other imaging (plain films, CT)