NM 4203NM 4203Scanning & ImagingScanning & Imaging

Skeletal SystemSkeletal System

Anatomy & Physiology of Anatomy & Physiology of BoneBone

Normal cortical bone is water, organic matter Normal cortical bone is water, organic matter (collagen, ground substance, cellular elements) (collagen, ground substance, cellular elements) and inorganic matter (bone mineral)and inorganic matter (bone mineral)

Bone salt mineral (inorganic matters) is composed Bone salt mineral (inorganic matters) is composed of calcium, phosphate, and hydroxyl, carbonate, of calcium, phosphate, and hydroxyl, carbonate, citrate, sodium, magnesium, potassium, chloride citrate, sodium, magnesium, potassium, chloride and fluoride.and fluoride.

Crystalline lattice structure Crystalline lattice structure hydroxyapatitehydroxyapatite

Skeleton performs several functions: Skeleton performs several functions: SupportSupport ProtectionProtection MovementMovement Blood formationBlood formation

Anatomy & physiology of Anatomy & physiology of BoneBone

Bone is metabolically active Bone is metabolically active tissue with nutrients being tissue with nutrients being exchanged between blood and exchanged between blood and bone.bone.

Main difference between bone Main difference between bone and other connective tissue is and other connective tissue is that it is calcified.that it is calcified.

Anatomy & Anatomy & Physiology of BonePhysiology of Bone Skeleton has two parts:Skeleton has two parts:

Axial: skull, spine and Axial: skull, spine and

thoracic girdlethoracic girdle Appendicular: upper Appendicular: upper

extremities, pelvis and extremities, pelvis and

lower extremitieslower extremities

Gross Structure of BoneGross Structure of Bone

Skeletal system contains 206 bonesSkeletal system contains 206 bones Tubular BonesTubular Bones

Humerus, radius, ulna, femur, tibia and Humerus, radius, ulna, femur, tibia and fibulafibula

Metacarpals, metatarsals, and phalangesMetacarpals, metatarsals, and phalanges Short BonesShort Bones

Wrist (carpals), ankle (tarsals), sesamoidsWrist (carpals), ankle (tarsals), sesamoids Flat BonesFlat Bones

Ribs, sternum, scapulae, several skull Ribs, sternum, scapulae, several skull bonesbones

Irregular BonesIrregular Bones Spine, pelvis, some bones in skullSpine, pelvis, some bones in skull

RadiopharmaceuticalsRadiopharmaceuticals

Can be analogs of calcium, Can be analogs of calcium, hydroxyl groups, or phosphateshydroxyl groups, or phosphates

First First 99m99mTc phosphate complex for Tc phosphate complex for bone imaging was introduced in bone imaging was introduced in 1971.1971.

Most widely used: Technetium based Most widely used: Technetium based methylene diphosphonate (MDP)methylene diphosphonate (MDP)

1818F FDG with PET imagingF FDG with PET imaging

AccumulationAccumulation

The mechanisms for bone accumulation The mechanisms for bone accumulation of imaging agents are not completely of imaging agents are not completely understood.understood.

It is probably related to the It is probably related to the exchange of the phosphorus groups exchange of the phosphorus groups onto the calcium of hydroxyapatite.onto the calcium of hydroxyapatite.

Calcium analogs or phosphate Calcium analogs or phosphate compounds have a low concentration in compounds have a low concentration in blood and tissue.blood and tissue.

99mTc phosphate will also show renal 99mTc phosphate will also show renal activity ~ these agents are excreted activity ~ these agents are excreted through the urinary tract.through the urinary tract.

Kit PreparationKit Preparation

Air should not be mixed into Air should not be mixed into the kit vial during the kit vial during preparation. This oxidation preparation. This oxidation would cause poor tagging.would cause poor tagging.

If injected over 4 hours after If injected over 4 hours after preparation, thyroid and preparation, thyroid and gastric activity may be seen.gastric activity may be seen.

Patient PreparationPatient Preparation

No prep before examNo prep before exam Following injection, they should Following injection, they should be well hydrated to help with be well hydrated to help with clearance from soft tissue.clearance from soft tissue. 4-6 glasses of liquid is adequate4-6 glasses of liquid is adequate They should be encouraged to void They should be encouraged to void frequently to reduce radiation frequently to reduce radiation dose to bladder.dose to bladder.

Common Reasons for Common Reasons for Bone ScanningBone Scanning

Detection or follow-up of metastatic disease Detection or follow-up of metastatic disease (breast, prostate or lung cancer)(breast, prostate or lung cancer)

Differentiate between osteomyelitis and Differentiate between osteomyelitis and cellulitiscellulitis

Determine bone viability (infarct or Determine bone viability (infarct or avascular necrosisavascular necrosis

Evaluate fracturesEvaluate fractures Evaluate prosthetic joints for loosening or Evaluate prosthetic joints for loosening or infectioninfection

Evaluate bone painEvaluate bone pain Evaluate finding on CT or RadiographEvaluate finding on CT or Radiograph Increased alkaline phosphataseIncreased alkaline phosphatase

TechniqueTechnique

Inject 10 – 25 mCi of Technetium based Inject 10 – 25 mCi of Technetium based radiopharmaceutical (usually MDP)radiopharmaceutical (usually MDP) Acquire blood flow and pool if neededAcquire blood flow and pool if needed

Image 2-4 hours laterImage 2-4 hours later Pt. should be well hydrated during the wait Pt. should be well hydrated during the wait time to help with soft-tissue clearance. time to help with soft-tissue clearance.

Pt. should void immediately prior to Pt. should void immediately prior to imagingimaging

Spot views or whole-body imagingSpot views or whole-body imaging SPECT may help improve lesion or fracture SPECT may help improve lesion or fracture localizationlocalization

Three-Phase Three-Phase

Blood FlowBlood Flow 2-4 second images for 40-60 seconds2-4 second images for 40-60 seconds

Blood PoolBlood Pool Static image obtained for 300,000-500,000 countsStatic image obtained for 300,000-500,000 counts

DelayDelay 2-4 hours after injection (5 + hrs. for 2-4 hours after injection (5 + hrs. for osteomyelitis of feet)osteomyelitis of feet)

300,000-500,000 count static images300,000-500,000 count static images 100,000 counts image should be done if 4100,000 counts image should be done if 4thth phase is phase is neededneeded

44thth phase: acquired 24 hours later phase: acquired 24 hours later 100,000 counts to compare to previous day100,000 counts to compare to previous day

SPECTSPECTSingle Photon Emission Computed Single Photon Emission Computed

TomographyTomography Pelvis, spine, TMJ, facial bones, kneesPelvis, spine, TMJ, facial bones, knees Detector to patient distance should be minimalDetector to patient distance should be minimal 30-45 minutes30-45 minutes Single head camera 64X64 matrixSingle head camera 64X64 matrix Newer cameras can use 128X128 matrixNewer cameras can use 128X128 matrix Large number of views 120 – 128 in 360 degreesLarge number of views 120 – 128 in 360 degrees

These parameters give very high counts and very high These parameters give very high counts and very high resolutionresolution

Reconstructed images include transverse, Reconstructed images include transverse, coronal and sagittal slicescoronal and sagittal slices

InstrumentationInstrumentation

Anger scintillation cameraAnger scintillation camera High-resolution collimatorHigh-resolution collimator Multiple, individual static Multiple, individual static images should be taken for images should be taken for equal amounts of time.equal amounts of time. Allows for comparison of image Allows for comparison of image densities.densities.

Normal ScanNormal Scan

Children: areas of growth (epiphyses) show Children: areas of growth (epiphyses) show intense uptakeintense uptake

Adults:Adults: Increase in nasopharynxIncrease in nasopharynx Skull may be patchySkull may be patchy Maxillary or mandibular activity due to dental Maxillary or mandibular activity due to dental diseasedisease

Increase in lower cervical spine and knees due to Increase in lower cervical spine and knees due to degenerative changesdegenerative changes

Anterior view: prominent sternum, sc joints, ac Anterior view: prominent sternum, sc joints, ac joints, shoulders, iliac crests and hips show joints, shoulders, iliac crests and hips show increase in activity.increase in activity.

Posterior view: thoracic spine, si joints and tips Posterior view: thoracic spine, si joints and tips of scapulae are prominentof scapulae are prominent

Any asymmetric activity is suspiciousAny asymmetric activity is suspicious

Causes for Increased Causes for Increased Activity Activity

Primary bone tumorPrimary bone tumor Metastatic DiseaseMetastatic Disease OsteomyelitisOsteomyelitis Trauma (fracture, postsurgical)Trauma (fracture, postsurgical) Loose prosthesisLoose prosthesis Degenerative or arthritic changesDegenerative or arthritic changes Osteoid osteomaOsteoid osteoma Paget’s DiseasePaget’s Disease

Generalized increased bone Generalized increased bone activity activity

Superscan Superscan

(no renal activity seen)(no renal activity seen) HyperparathyroidismHyperparathyroidism Renal osteodystrophyRenal osteodystrophy Diffuse metastasesDiffuse metastases Hematologic disordersHematologic disorders

Poor scanPoor scan

Decreased cardiac outputDecreased cardiac output Renal failureRenal failure Extravasation of Extravasation of radiopharmaceutical during radiopharmaceutical during injectioninjection

Kit breakdownKit breakdown

Metastatic DiseaseMetastatic Disease

30-50% of patients with metastases do not have pain30-50% of patients with metastases do not have pain Tumors that are more likely to spread to bone: Tumors that are more likely to spread to bone: breast, lung and prostatebreast, lung and prostate

Tumors with low rates of bone metastases: colon, Tumors with low rates of bone metastases: colon, cervix, uterus, head and neckcervix, uterus, head and neck

Most metastases are seen in multiple areas. Most metastases are seen in multiple areas. (exception is single sternal lesion in breast (exception is single sternal lesion in breast cancer pt.)cancer pt.)

PSA (prostate-specific antigen): less than 10-15 PSA (prostate-specific antigen): less than 10-15 ng/mL = likelyhood of positive bone scan with ng/mL = likelyhood of positive bone scan with metastases is low.metastases is low.

Cold lesions: extremely aggressive tumor, decreased Cold lesions: extremely aggressive tumor, decreased blood supply, or significant marrow involvement.blood supply, or significant marrow involvement.

Osteogenic SarcomaOsteogenic Sarcoma

Osteosarcoma is a Osteosarcoma is a bone-forming lesionbone-forming lesion Appearance varies Appearance varies widely depending on widely depending on the vascularity and the vascularity and aggressiveness of the aggressiveness of the tumor.tumor. Increased activity is usually intense Increased activity is usually intense and often patchy with photopenic and often patchy with photopenic areas.areas.

Ewing’s SarcomaEwing’s Sarcoma

Relatively common bone tumorRelatively common bone tumor Occurs mostly in pelvis or femurOccurs mostly in pelvis or femur Activity is intense and homogeneous.Activity is intense and homogeneous. Tumor is very vascularTumor is very vascular

40-50% of patient’s with Ewing’s 40-50% of patient’s with Ewing’s sarcoma or osteosarcoma develop sarcoma or osteosarcoma develop metastases within 2 years. Follow-up metastases within 2 years. Follow-up bone scans are recommended.bone scans are recommended.

TraumaTrauma

Bone scan appearance of Fractures:Bone scan appearance of Fractures: Acute: 3-4 weeks~generalized diffuse increase Acute: 3-4 weeks~generalized diffuse increase around fracture sitearound fracture site

Subacute: 2-3 months~activity more localized and Subacute: 2-3 months~activity more localized and intenseintense

Healing phase: longer period ~gradual decline in Healing phase: longer period ~gradual decline in intensity intensity

Early increase in activity is a result of Early increase in activity is a result of hyperemia and inflammation.hyperemia and inflammation.

Repair begins within a few hours and reaches Repair begins within a few hours and reaches maximum in 2-3 weeks.maximum in 2-3 weeks.

Age: has been found to be a minor variable. Age: has been found to be a minor variable. However, about 3 days are needed to detect However, about 3 days are needed to detect occult hip fracture in elderly patients.occult hip fracture in elderly patients.

Avascular NecrosisAvascular Necrosis

Involving the hipInvolving the hip Usually due to traumaUsually due to trauma

Decrease in blood flow and Decrease in blood flow and

blood poolblood pool Decreased activity on Decreased activity on

delay imagesdelay images

MRI can also be done for thisMRI can also be done for this

Stress FracturesStress Fractures

Not visualized for 7 to 10 days on Not visualized for 7 to 10 days on radiograph.radiograph.

Can be seen on a radionuclide bone scan Can be seen on a radionuclide bone scan about 24 hrs. after onset of pain.about 24 hrs. after onset of pain.

Stress fractures: increased blood flow and Stress fractures: increased blood flow and pool~delay tends to image as a focal hot pool~delay tends to image as a focal hot spot.spot.

Shin splints: normal blood flow and blood Shin splints: normal blood flow and blood pool~delay shows linear increased activity pool~delay shows linear increased activity along posteromedial tibial cortex.along posteromedial tibial cortex.

Child AbuseChild Abuse

Rib and thoracic spine Rib and thoracic spine fractures are a strong fractures are a strong indication of physical abuse.indication of physical abuse.

Osteomyelitis, Cellulitis Osteomyelitis, Cellulitis & &

Septic ArthritisSeptic Arthritis Radiopharmaceuticals: Radiopharmaceuticals:

99m99mTc –diphosphonateTc –diphosphonate6767Ga citrateGa citrate111111In labeled leukocytesIn labeled leukocytes99m99mTc labeled leukocytesTc labeled leukocytes

Cellulitis: increased blood flow and blood Cellulitis: increased blood flow and blood pool, no focal area of increase on delay.pool, no focal area of increase on delay.

Osteomyelitis: increased blood flow and Osteomyelitis: increased blood flow and blood pool, with focal increased area on blood pool, with focal increased area on delay. Usually only on one side of a joint.delay. Usually only on one side of a joint.

Septic Arthritis: increased activity in all Septic Arthritis: increased activity in all three phases. Involved both sides of the three phases. Involved both sides of the joint.joint.

Paget’s DiseasePaget’s Disease

Intense increase in activity due Intense increase in activity due to increased regional blood to increased regional blood flow.flow.

Usually conforms to the shape of Usually conforms to the shape of the involved bone.the involved bone.

Notable expansion or Notable expansion or

enlargement of the enlargement of the

bone.bone.

Reflex Sympathetic Reflex Sympathetic DystrophyDystrophy(RSD)(RSD)

Usually prior trauma, myocardial Usually prior trauma, myocardial infarction, or neurologic infarction, or neurologic abnormality.abnormality.

Increased blood flow and Increased blood flow and

blood pool to affected limb, blood pool to affected limb,

increased asymmetric increased asymmetric

periarticular activity aroundperiarticular activity around

all joints of hand or foot.all joints of hand or foot.

Bone Marrow ImagingBone Marrow Imaging

Radiopharmaceutical: 99mTc sulfur Radiopharmaceutical: 99mTc sulfur colloidcolloid Localizes in marrow because the Localizes in marrow because the particles are phagocytized by RES particles are phagocytized by RES cells in the marrow.cells in the marrow.

Intense liver and spleen activity Intense liver and spleen activity must be covered with a lead shield.must be covered with a lead shield.

MRI usually doneMRI usually done

Joint ImagingJoint Imaging

Evaluate inflammatory joint Evaluate inflammatory joint diseasedisease

Radiopharmaceuticals:Radiopharmaceuticals: 99m99mTc pertechnetateTc pertechnetate 99m99mTc phosphate compounds (most Tc phosphate compounds (most sensitive for knee or sacroiliac sensitive for knee or sacroiliac inflammatory disease)inflammatory disease)

Can detect disease before Can detect disease before radiographsradiographs

Therapy of Painful Bone Therapy of Painful Bone MetastasesMetastases

Lesions that are unresponsive to Lesions that are unresponsive to radiotherapy or chemotherapy.radiotherapy or chemotherapy.

Usually men with prostate cancerUsually men with prostate cancer For pain management (not a cure)For pain management (not a cure) Increase in pain 2-3 days after Increase in pain 2-3 days after treatment and can last several days.treatment and can last several days.

Pain improvement starts at 7-20 days Pain improvement starts at 7-20 days after treatment and can last 3-6 after treatment and can last 3-6 months.months.

Routine bone scan is done first to Routine bone scan is done first to ensure there will be bone uptake.ensure there will be bone uptake.

Therapy of Painful Bone Therapy of Painful Bone MetastasesMetastases

Radiopharmaceutical: Strontium-89 chloride Radiopharmaceutical: Strontium-89 chloride (Metastron)(Metastron) Decays by beta-emissionDecays by beta-emission Half-life 50.6 daysHalf-life 50.6 days

Depresses the bone marrow and should not be used Depresses the bone marrow and should not be used if leukocyte or platelet count is low.if leukocyte or platelet count is low.

Typical dose is 40-60 uCi / kg : up to 4mCiTypical dose is 40-60 uCi / kg : up to 4mCi Slow 1-2 minute injection using plastic shieldingSlow 1-2 minute injection using plastic shielding

Should not be given to patients with life Should not be given to patients with life expectancy less than 3 months. Patients cannot be expectancy less than 3 months. Patients cannot be cremated in many states.cremated in many states.

Cost : $3000 + (cost effective compared to Cost : $3000 + (cost effective compared to radiation therapy, chemotherapy, and analgesic radiation therapy, chemotherapy, and analgesic pain medicationpain medication

Therapy of Painful Bone Therapy of Painful Bone MetastasesMetastases

Other Radiopharmaceuticals:Other Radiopharmaceuticals: Rhenium-186 HEDP ~not approved in the Rhenium-186 HEDP ~not approved in the U.S., but widely used in EuropeU.S., but widely used in Europe

Samarium-153 EDPMT (Quadramet)Samarium-153 EDPMT (Quadramet) Short half-life of 46 hoursShort half-life of 46 hours In addition to beta emission, also has a In addition to beta emission, also has a gamma emission that can be imagedgamma emission that can be imaged

Usually scanned 6 hrs after administeredUsually scanned 6 hrs after administered