2. bone scan - chest imaging(2010)

7/29/2019 2. BONE SCAN - Chest Imaging(2010)

1/38

BONE ISOTOPE SCAN

--


2/38

Introduction

Bone scan is one of the most commonly

performed procedures in nuclear

medicine.

Bone scan often provides an earlier

diagnosis and demonstrates more lesions

than are found by radiographic

procedures.


3/38

Sensitivity and Specificity

Bone scan is very sensitive study but it is

not specific.

Although findings on bone scan are non-

specific, its monostotic or polyostotic

status and anatomical distribution can

provide important clues to the differential

diagnosis.


4/38

Radiopharmaceuticals

They are bone seeking agents.

They are labeled with Tc99m.

They are phosphate analogs. Most commonly used one is HDP

(Hydroxy Methylene Diphosphonates).

They are given intravenously.


5/38

Mechanism of Localization

Phosphate groups bind to the hydroxyapatite

[Ca3(Po4)2] structure of bone tissue by a

mechanism called chemisorption.

The hydroxyapatite structure of the bone isexposed during bone remodeling. So, more

radiopharmaceutical will deposit in that region

giving hot area.

50-60% of injected dose localized on bone,

remain dose is cleared by kidneys.


6/38

Whole body bone scan

This is the bony phase of bone scan.

Inject radiopharmaceutical and image in

2-4 hours.

When we say bone scan, we usually

mean whole body bone scan.


7/38


8/38


9/38


10/38


11/38

Three Phase Bone Scan

It is done to see if there is soft tissue

hyperemia.

First phase is the perfusion phase or

vascular phase.

Second phase is the blood pooling phase

or soft tissue phase.

Third phase is the bony phase.


12/38

First Phase

30-60 dynamic images are usually

obtained over 1 minute immediately after

injection.

This is radionuclide angiography and gives

an idea about the local vasculature. During

the first minute after injection, injected

dose is still intravascular.


13/38

Perfusion


14/38

Second Phase

Static image is obtained in 5 minutes after

dose injection.

Within 5 minutes post injection,

radiopharmaceutical moves from

intravascular space to extravascular space

(soft tissue). It gives idea about soft tissue

edema.


15/38

Blood Pool


16/38

Hyperemia

If there is focal increased activity in

the first and second phases,

hyperemia or acute inflammatoryprocess is present.


17/38

Third Phase

It is the bony phase image obtained in

2-4 hours post injection.

It is the same as whole body bonescan.


18/38

Clinical Applications

Malignancy

1- Primary bone cancer

2- Secondary metastatic bone disease

Osteomyelitis

Stress fractures


19/38

Primary Bone Malignancy

(Sarcomas)

MRI provides more exact information

regarding tumor extent, particularly in soft

tissue. So, bone scan is not a diagnosis

image in primary bone tumors.


20/38

Bone sarcomas-cont..

Bone scan is a staging and restaging

image in bone sarcomas. It is performed to

see if there is bone metastatic disease

(bone to bone).

40 50% of patients with either Ewings

sarcoma or osteosarcoma develop

osseous metastases within 2 years ofpresentation.


21/38


22/38


23/38

Metastatic Bone Disease

Bone scan is an extremely important tool

in decision making during management of

cancer patients.

Any cancer potentially could cause bone

metastatic disease.

However, prostate, breast and lung

cancers have propensity to metastasize to

bone.


24/38

Metastatic Bone Disease and

Bone Pain

About 80% of patients with known cancer

and bone pain have metastases

documented by bone scan.

30 50% of patients with metastatic bone

disease do not have bone pain.


25/38

Metastatic Bone Disease and

Image Findings

The hallmark of metastatic bone

disease is multiple foci of increased

osteoblastic activity in bony skeleton.However, single lesion could be also

metastatic.


26/38


27/38


28/38


29/38


30/38


31/38

Stress Fractures

It is often difficult to visualized on a plain

radiograph.

Fractures may be identified by bone scan

as early as 24 hours after occurrence.

3-phase bone scan is usually done.

There is hyperemia and osteoblastic

process (three phases are positive).


32/38

Stress Fracture

Blood Pool

Anterior Posterior

Anterior Posterior Left Lat Right Lat

Left Lat Right Lat

2 hour delay


33/38

Stress Fracture


34/38

Acute Osteomyelitis

Early plain radiography signs of

osteomyelitis are non-specific.

3-phase bone scan is usually theprocedure of choice to differentiate

between osteomyelitis and cellulitis.


35/38

Acute Osteomyelitis-cont..

If first and 2nd phases are positive

(hyperemia) with normal third phase,

diagnosis would be cellulitis. In acute osteomyelitis all 3-phases

are positive (hyperemia and

osteoblastic process in the bone).


36/38

Perfusion


37/38

Blood Pool


38/38

Whole BodyBone Scan

2. bone scan - chest imaging(2010)

Documents