2. BONE SCAN (2010)

2. BONE SCAN (2010) - ‫‪BONE ISOTOPE SCAN‬‬...

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Unformatted text preview: ‫‪BONE ISOTOPE SCAN‬‬ ‫‪BONE‬‬ ‫الدكتور قصي المقبل‬ ‫أستاذ مشارك- قسم الشعة والطب‬ ‫النووي‬ ‫كلية الطب-جامعة العلوم والتكنولوجيا‬ ‫الردنية‬ Introduction Introduction Bone scan is one of the most commonly Bone performed procedures in nuclear medicine. medicine. Bone scan often provides an earlier Bone diagnosis and demonstrates more lesions than are found by radiographic procedures. procedures. Sensitivity and Specificity Sensitivity Bone scan is very sensitive study but it is Bone not specific. Although findings on bone scan are nonspecific, its monostotic or polyostotic specific, status and anatomical distribution can provide important clues to the differential diagnosis. diagnosis. Radiopharmaceuticals Radiopharmaceuticals They are bone seeking agents. They are labeled with Tc99m. They are phosphate analogs. Most commonly used one is HDP Most (Hydroxy Methylene Diphosphonates). (Hydroxy They are given intravenously. Mechanism of Localization Mechanism Phosphate groups bind to the hydroxyapatite Phosphate [Ca3(Po4)2] structure of bone tissue by a mechanism called chemisorption. mechanism The hydroxyapatite structure of the bone is The exposed during bone remodeling. So, more radiopharmaceutical will deposit in that region giving “hot” area. giving 50-60% of injected dose localized on bone, 50-60% remain dose is cleared by kidneys. remain Whole body bone scan Whole This is the bony phase of bone scan. Inject radiopharmaceutical and image in Inject 2-4 hours. 2-4 When we say bone scan, we usually When mean whole body bone scan. Three Phase Bone Scan Three It is done to see if there is soft tissue It hyperemia. hyperemia. First phase is the perfusion phase or First vascular phase. vascular Second phase is the blood pooling phase Second or soft tissue phase. or Third phase is the bony phase. First Phase First 30-60 dynamic images are usually 30-60 obtained over 1 minute immediately after injection. injection. This is radionuclide angiography and gives This an idea about the local vasculature. During the first minute after injection, injected dose is still intravascular. Perfusion Perfusion Second Phase Second Static image is obtained in 5 minutes after Static dose injection. dose Within 5 minutes post injection, Within radiopharmaceutical moves from intravascular space to extravascular space (soft tissue). It gives idea about soft tissue edema. Blood Pool Blood Hyperemia Hyperemia If there is focal increased activity in If the first and second phases, hyperemia or acute inflammatory process is present. process Third Phase Third It is the bony phase image obtained in It 2-4 hours post injection. 2-4 It is the same as whole body bone It scan. Clinical Applications Clinical Malignancy Malignancy 1- Primary bone cancer 12- Secondary metastatic bone disease 2- Osteomyelitis Osteomyelitis Stress fractures Stress Primary Bone Malignancy Primary (Sarcomas) MRI provides more exact information MRI regarding tumor extent, particularly in soft tissue. So, bone scan is not a diagnosis image in primary bone tumors. image Bone sarcomas-cont.. Bone Bone scan is a staging and restaging Bone image in bone sarcomas. It is performed to see if there is bone metastatic disease (bone to bone). (bone 40 – 50% of patients with either Ewing’s sarcoma or osteosarcoma develop osseous metastases within 2 years of presentation. presentation. Metastatic Bone Disease Metastatic Bone scan is an extremely important tool Bone in decision making during management of cancer patients. cancer Any cancer potentially could cause bone Any metastatic disease. However, prostate, breast and lung However, cancers have propensity to metastasize to bone. Metastatic Bone Disease and Bone Pain Bone About 80% of patients with known cancer About and bone pain have metastases documented by bone scan. documented 30 – 50% of patients with metastatic bone 30 disease do not have bone pain. Metastatic Bone Disease and Image Findings Image The hallmark of metastatic bone The disease is multiple foci of increased osteoblastic activity in bony skeleton. However, single lesion could be also metastatic. metastatic. Stress Fractures Stress It is often difficult to visualized on a plain It radiograph. radiograph. Fractures may be identified by bone scan Fractures as early as 24 hours after occurrence. as 3-phase bone scan is usually done. 3-phase There is hyperemia and osteoblastic There process (three phases are positive). process Stress Fracture Stress Anterior Posterior Left Lat Right Lat Blood Pool Anterior Posterior Left Lat 2 hour delay Right Lat Stress Fracture Stress Acute Osteomyelitis Acute Early plain radiography signs of Early osteomyelitis are non-specific. osteomyelitis 3-phase bone scan is usually the 3-phase procedure of choice to differentiate between osteomyelitis and cellulitis. between Acute Osteomyelitis-cont.. Acute If first and 2nd phases are positive If (hyperemia) with normal third phase, diagnosis would be cellulitis. diagnosis In acute osteomyelitis all 3-phases In are positive (hyperemia and osteoblastic process in the bone). osteoblastic Perfusion Perfusion Blood Pool Blood Whole Body Bone Scan Bone ...
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