99Tc Bone Imaging :99Tc Bone Imaging NMT 1713


Outline :Outline What is Bone? Facts on Technetium Nuclear Medicine Bone Imaging Agents Images Conclusion References


What is Bone? :What is Bone? Living tissue that makes up the body’s skeleton Provide shape and support for the body Provide protection for some organs Storage site for minerals Mostly made of collagen and calcium phosphate 206 bones in the human skeleton


Tubular bones :Tubular bones Long tubular (long) bones include: humorous, radius, ulna, femur, tibia, and fibula Short tubular (long) bones include: metacarpals, metatarsals, and phalanges Short bones include: wrist (carpals), ankle (tarsals), sesamoids (small bones in a tendon or joint capsule) and other extra bones


Bones :Bones Irregular bones include: bones of the spine, and pelvis, and some of the Flat bones include: ribs, sternum, and scapulae and several skull bones. skull bones. All bones have a cortex (compact bone), surrounding various amounts of cancellous (spongy or trabecular) bone, which contains blood forming elements.


Joints :Joints Spaces where bones come into contact and are bridged in some manner. Generally have a variable amount of movement. Classified into two main types according to movement: rigid (synartroses) or freely moveable (diarthroses)


Normal vs Abnormal :Normal vs Abnormal (from Texas Department of Health webpage)


Technetium :Technetium Atomic Number 43 Crystalline transition metal Not found in nature Occurs as one of the fission products of Uranium Melting point 2430 K Boiling point 4538 K


99 Tc :99 Tc Oxidation state (+2, +4, +5, +6, and +7) Half life of 6.01 hours Used in more than 90% of the diagnostic scans performed in nuclear medicine departments in the United States Has no beta emission, and emits only low-energy No stable isotopes exist


Nuclear Medicine :Nuclear Medicine Specialty in which a wide range of clinical conditions are investigated using radioactive tracers administered to the patient It is completely different process from X-Ray, CT and MRI scan (these look at the anatomy of the body) To look at the function of the body, Nuclear Medicine uses gamma rays


Nuclear Medicine :Nuclear Medicine Gamma rays are very similar to X-Rays, but the major difference is that the gamma rays are emitted by pharmaceuticals injected into the bloodstream rather than being produced by machines outside the body. Gamma rays are detected by the gamma camera


Gamma Rays :Gamma Rays (from Doe Medical Sciences webpage)


Radionuclide imaging :Radionuclide imaging Bone imaging is one of the most commonly ordered procedures in nuclear medicine. Standard clinical indications include: Staging of malignant disease, screening patients with primary tumors: (breast, lung, prostate) known to metastasize to bone. Evaluation of response to therapy. Evaluation of primary bone neoplasm's ,(ewing’s sarcoma, osteogenic sarcoma)


Radionuclide imaging :Radionuclide imaging Diagnosis of skeletal inflammatory disease (osteomyelitis) Evaluation of unknown skeletal pain. Determination of bone viability when blood supply to area is in question. Detection of occult fractures not detected by x-ray. Staging for malignant disease is the most common.


Past and present radiopharmaceuticals :Past and present radiopharmaceuticals Early applications of radionuclides for bone imaging were performed with phosphorous-32 and calcium-45. Used to observe bone structure and function Pure beta emitters, accumulation in regions of increased bone minerals Limited external measurement


Radiopharmaceuticals :Radiopharmaceuticals Strontium-85 allowed for clinical applications. It’s a calcium analog that produced gamma rays. Could be detected externally. Introduction of the rectilinear scanner in the early 1960’s made bone scanning possible. High radiation dose limited it to patients with known malignancies. Sr-85 has a half life of 65days and a 513 kev. Limited amount injected to 100 uci. Scan times long and images poor.


Radiopharmaceuticals :Radiopharmaceuticals Sr-85 accumulation in bone was rapid but blood and GI clearances where long. Scan times b/w injection and scan was 2-7 days. Sr-87m was used, has shorter half life, gamma energy of 388kev. Short half life allowed for higher doses of 1-4 mci and scanning time could be done 2-3 hrs later. Very expensive to produce


Radiopharmaceuticals :Radiopharmaceuticals Flourine-18 first to have acceptable radiation dose, late 60,s early 70’s Provided superior scans Good clearance from blood to bone. F-18 half life 1.87hrs and high expense to produce made it unsuitable. Rectilinear scanners was suitable for the 511 kev annihilation radiation, yet scintillation cameras unable to detect.


Radiopharmaceuticals :Radiopharmaceuticals The development of technetium labeled phosphate complexes was introduced in 1971 Short half life allows for several millicuries to be injected Ideal for scintillation camera and also has great imaging properties. Allows for high information densities to be obtained.


Radiopharmaceuticals :Radiopharmaceuticals Polyphosphate was first commercially available Tc 99m labeled compound for bone imaging Long phosphate chemical chains can cause radiocoloid in bloodstream, thus allowing greater hepatic (liver) uptake. Further development reduced the chemical chain and more stable phosphate complexes, which are pyrophosphate.


Pyrophosphate (PYP) :Pyrophosphate (PYP) Originally used (1970’s) Still approved to be used today but no longer used in skeletal imaging because of the improved efficacy of the diphosphonates The P-O-P bond is instable in skeletal imaging, whereas the P-C-P linkage is very stable


Diphosphonate :Diphosphonate MDP (methylene diphosphonate), HDP (hydroxymethylene diphosphonate) are currently the two radiopharmaceuticals of choice. MDP has been shown to have a faster blood clearance than other phosphanate compounds. HDP has a greater bone uptake. 50/50= approx. 50% of tracer is concentrated in boney tissue, while the other 50% is excreted by the kidneys (urine)


MDP :MDP Most widely used radiopharmaceutical for skeletal imaging When injected IV, 99Tc-MDP is rapidly cleared form the blood 10% of dose remains in blood 1 hour post-injection, 5% at 2 hours, and less than 1% remains at 24 hours


99Tc-MDP :99Tc-MDP Bone scans are commonly performed for evaluation of osteomyelitis Major advantage is its widespread availability To minimize the radiation dose to the bladder, the patient should increase fluid intake and to void as often as possible after the injection, and for 4-6 hours after the imaging procedure


99 m Tc HDP :99 m Tc HDP Greater bone uptake, then MDP. Both HDP and MDP have similar imaging properties Both HDP and MDP have lower blood and tissue concentrations.


Methods of administration :Methods of administration IV (intravenous) access. Straight stick (without IV line) straight into vein. Existing IV line with a saline flush. Flow studies (triple phase bone flow) require good bolus injection


Accumulation in bone :Accumulation in bone Accumulation in bone of radionuclides is related to vascularity and rate of bone production Increased blood supply to an area of bone (blood pool image) can be seen immediately post-injection and has increased activity (uptake) of radiopharmaceutical Localization of bone imaging agent is related to the exchange of ions in the bone.


Accumulation in bone :Accumulation in bone Accumulation of labeled phosphate compounds is probably related to the exchange of phosphorus groups onto the calcium of hydroxyapatite. The mechanisms for bone uptake are not completely understood. The principal mechanism is fairly basic calcium analogs and phosphate compounds have low concentration in blood and tissue. Thus accumulate in bone.


Accumulation in bone :Accumulation in bone Bone imaging agents can accumulate in soft tissue. Localization of bone imaging agent could signify calcification, infarction, inflammation, trauma, and tumor. Radiopharmaceutical that does not accumulate in the bones is excreted by the body via various routes. Sr 85 GI tract(for several days), F18 and Tc99m excreted via urine, (see activity in bladder and kidneys)


Patient preparation :Patient preparation Preparation of patients is minimal for bone imaging. Identify patient Verify order Explain procedure Instruct patient to drink 4-6 glasses of any fluid. Instruct patient to return in 2-3 hours, post injection, WHY???


Patient preparation :Patient preparation Upon return patient should void prior to scan in order to eliminate any obstruction caused by the large amount of radioactivity in the bladder. Care must be taken to avoid contamination of clothing, undergarments, skin, etc. which could lead to false-positives.


Instrumentation :Instrumentation Several types of instruments have been used for bone imaging. Rectilinear scanner one of the first instruments to image bones Anger camera with a large field of view. Low energy high resolution (LEHR) or low energy all-purpose, (LEAP) generally the collimators of choice.


Gamma Camera :Gamma Camera (taken from Derriford Co UK webpage)


Gamma Camera :Gamma Camera Used to detect the gamma rays from the radiopharmaceutical and to build them up into an image or series of images The camera may take a single image or a whole body image Optimum scanning is achieved during 2-4 hours after 99Tc-MDP/HDP is administered


Instrumentation :Instrumentation 4 methods of imaging: Flow, static imaging, whole body imaging, or SPECT Flow or triple phase bone scan, inject radiotracer start images immediately, dynamic images 2-4sec/frame, obtain immediate static blood pool image for counts(200,000-500,000cts) Center camera over ROI (region of interest)


Instrumentation :Instrumentation Static imaging is obtained 2-4 hrs later. Static images are obtained for counts (400,000-600,000 cts) Entire body images are obtained: anterior: pelvis femur, knees, tib/fib, feet, abdomen, thorax, bilat shoulders, head. Posterior: pelvis, abdomen, thorax arms down, head. 24hr image obtained upon request


Instrumentation :Instrumentation Whole body imaging is also obtained 2-4 hrs later. Whole body “sweep” can be obtained with single or dual head camera. Imaging with single head camera: all anterior images, flip for all posterior images. Imaging with dual head camera one pass. All anterior and posterior images obtained 24hr images obtained upon request.


Instrumentation :Instrumentation SPECT is obtained at 2-4 hrs post –injection. Camera is positioned around ROI (region of interest) 360 degree (single head) or 180 degree (dual head) 60/64 steps, 20/40 sec/frame. Images obtained: transverse, coronal, and sagital slices. (images on pg. 506)


Normal results :Normal results Symmetric uptake throughout skeletal system. Kidneys show lightly, bladder shows brightly. Pediatrics: epiphyseal plates and cranial structures show brightly New fractures show 3-5 days post/ or as early as 24hrs.


Abnormal results :Abnormal results Asymmetric, or focal areas of uptake Super scan: caused by widespread metastatic disease Non-tumor causes of hyperparathyroidism, osteomalacia, pagets disease. Diminished activity. Increased activity in flow,blood pool, and delay imaging.


Radionuclide therapy :Radionuclide therapy Bone metastasis's such as breast, lung, prostate, kidney and thyroid once spread to bones can cause pain. two radiopharmaceuticals are used Sr89 chloride (T1/2=50.5 days) pure beta emitter, and Sm153 samarium (T1/2=1.9 days) Results are similar and response rates for pain relief have varied.


Radionuclide therapy :Radionuclide therapy Adult dose ranges: Sr89 40-60 uCi per/kg (1.48-2.22 MBq). Sm153 1mCi per/kg (37 MBq) Administration: syringe shield, patent IV line, flush Must be administered by nuclear physician, radiologist, ordering physician.


Images :Images Normal Metastases


Slide 44:Pagets Disease Normal


Slide 45:Osteosacroma in a child Normal


Slide 46:Osteoid Osteoma


Slide 47:Septic arthritis


Slide 48:Osteomyelitis of left femur


HELLO!!!!!!!! :HELLO!!!!!!!! ANY QUESTIONS??


Conclusion :Conclusion 99Tc-MDP is the most widely used of the diphosphonate ligands 99Tc accounts for over 90% of the investigations carried out today 99Tc is ideal for nuclear medicine purposes because it combines good imaging characteristics with a low radiation to the patient


References :References Kanvinde, M and Faulhaber, P; Nuclear and SPECT Teaching Files Case 33, 2000. (www.uhrad.com/spectarc) Jones, Ivor and Nevin, Sue; What is Nuclear Medicine, September 30,1999. (www.derriford.co.uk/numed) Jurisson, S.; Berning, D.; Jis, W.; Ma, D.; Coordination Compounds in Nuclear Medicine, December 14, 1992. (pages 1137-1156) Pollen J; Witztum K; Basarab R, Expanded 99Tc-MDP bone scan, December 1984 (pages 632-638) Texas Department of Health, What is Bone, 2002. (www.edh.state.tx.us/osteo/bone.htm) University of Maryland Medicine, All About Bone, 2003. (www.umm.edu/bone)


Clinical indications :Clinical indications Staging of malignant disease Evaluation of primary bone neoplasm's Diagnosis of early skeletal inflammatory disease Evaluation of skeletal pain Evaluation of elevated alkaline phosphate. Determination of bone viability Evaluation of painful joint pain.