Chapter 23: Recognizing Abnormalities Of Bone Density Flashcards
What is an orthogonal view?
Two X-rays taken at 90 degrees to each other
What are examples of Increased Bone Density?
Diffuse osteoblastic metastases
Localized osteoblastic metastases
Avascular necrosis of bone
Paget Disease
What are examples of decreased bone density?
Osteoporosis
Hyperparathyroidism
Localized osteoblastic metastases
Multiple Myeloma
Osteomyelitis
What diseases will cause focal increase in bone density?
Carcinoma of the prostate
Avascular necrosis of bone
Paget Disease
What is Technetium-99M used for?
The radionuclide used to tag MDP in bone scans because is affixes to bone surface
What does activity in bone depend upon?
Blood supply and rate of bone turnover
What processes may produce false-negative scans?
Those with extremely high or extremely low bone turnover
What do osteoblastic lesions show on Xray?
Increased activity by uptake of radiotracer
What is the initial study of choice when looking for myeloma lesions? Why?
Conventional X-rays because the bone is much less sensitive in detecting multiple myeloma
Bone scans are…
Highly sensitive and not very specific; positive scan will require another imaging procedure to rule out nonmalignant cause of positive bone scan
What diseases cause INtravascular necrosis of bone?
Sickle Cell Disease
Polycythemia Vera
What diseases cause Vascular Necrosis of Bone?
Vasculitis induced by lupus or radiation
What diseases cause Extravascular Necrosis of bone?
Trauma
What diseases cause idiopathic avascular necrosis of bone?
Exogenous steroids and Cushing Disease
Legg-Calve-Perthes Disease
What diseases cause a diffuse decrease in bone density?
Osteoporosis
Hyperparathyroidism
What is primary hyperparathyroidism?
Caused by single adenoidal in 80-90% of patients and almost always results in hypercalcemia
What is secondary hyperparathyroidism?
Caused by hyperplasia of glands secondary to imbalances in calcium and phosphorous levels
Seen mostly with chronic renal disease
What is tertiary hyperparathyroidism?
Occurs in patients with long-standing secondary hyperparathyroidism
Patient has autonomous hypersecretion of PTH causing hypercalcemia
Diseases that cause focal decrease in bone density?
Metastatic Disease to Bone
Multiple Myeloma
Osteomyelitis
What are the two categories of metastases to bone?
Osteoblastic and osteoblastic
What is osteoblastic metastases to bone?
Stimulates the production of new bone
What are osteolytic metastases to bone?
Destroy bone
Where are metastatic bone lesions uncommon and if they are present here, what are they caused by?
Distal to the elbow or knee
Caused by lung or breast cancer
What is the study of choice for detecting skeletal metastases?
Radionuclide bone scan
What are some causes of osteoblastic bone metastases?
Prostate carcinoma
Breast carcinoma
Lymphoma
Carcinoid tumors (rare)
What are some causes of osteolytic bone metastases?
Lung Cancer (men)
Breast Cancer (women)
Renal Cell carcinoma
Thyroid Carcinoma
What are insufficiency fractures?
Type of Pathologic fracture in which mechanically weakened bone fractures as result of a normal or physiologic stress
What are insufficiency fractures most common secondary to?
Osteoporosis in postmenopausal women
What are common sites of insufficiency fractures?
Pelvis Thoracic Spine Sacrum Tibia Calcaneus
How to insufficiency fractures appear on Xray?
They have a sclerotic band representing healing
What studies are most sensitive to detecting insufficiency fractures?
CT
MRI
NMT
What do bones consist of?
Cortex = compact bone
Medullary cavity = cancellous bone
What is cancellous bone arranged as?
Trabeculae
Blood vessels
Hematopoietic cells
Fat
Where is the cortex best seen on X-rays?
In tangent
What is MRI particularly sensitive to?
Assessment of bone marrow
What tests are superior to X-rays for evaluation of soft tissues?
MRI and CT
What does increased osteoblastic activity produce?
Focal or generalized decreases in bone density
What does increased osteoblastic activity produce?
Focal or diffuse increased bone density
What are the hallmarks of Paget Disease?
Thickening of the cortex
Accentuation of the trabecular pattern
Enlargement and increased density of the affected bone
What is plasmacytomas and what can they produce?
Precursors to multiple myeloma/most common primary tumor of bone
Produce focal areas of decreased bone density
What do osteolytic metastatses produce?
Focal areas of decreased bone density
What is osteoporosis characterized by?
Low bone mineral density
Predisposes persons to Pathologic fractures
What percentage of bone must be reduced in order to tell the difference in density on X-rays?
50%
What test is most sensitive to presence of medullary metastatic disease?
MRI
