RADIO- ISOTOPE SCANS

• The gamma camera, also known as the scintillation or Anger camera is a device used in nuclear medicine.
• The radionuclide emits faint gamma ray signals from inside the body (after administration into body) which are measured by Gamma Camera.
• Tc-99 is the most common radionuclide used for imaging in nuclear medicine.

 Various Radio- isotope scans-

Bone Scintigraphy-

• Tc- 99- MDP is the most commonly used for skeletal imaging.
• Conditions in which increased uptake on bone scan or Hot spot is seen at new bone formation in as-

1. Osteomyelitis
2. Bone tumours, Fibrous dysplasia, osteoblastic metastasis
3. Paget’s disease
4. Endocrine- Hyperparathyroidism

• Conditions in which there is no osteoblastic activity and have no radioisotope uptake or cold spot on bone scan are-

1. Multiple myeloma
2. Fibrous cortical defect
3. Pseudarthrosis/ non union 

Cardiac radionuclide scanning-

a) Myocardial imaging

i) Infarct scanning-

• TC- 99m pyrophosphate is used most commonly.
• Infarct appears as Hot spot.

ii) Perfusion scanning

• It is useful in diagnosis of CAD.
• Used to identify areas of reversibility after MI.
• Thallium 201is most commonly used for radionuclide for this purpose.

b) Nuclear angiography-

      1. First pass technique- used for study of intracardiac shunts. Technetium- 99 is used.

      2. Multigated equilibrium studies (MUGA/ radionuclide cardiac ventriculography).

• Tc- 99 – albumin is used most commonly.

iii) Renal radionuclide imaging-

a) Dynamic renal scintigraphy-

• Also called as functional imaging as it assesses impaired renal function.
• Radionuclides used are-

1. Tc- 99- DTPA → GFR estimation
2. Tc- 99- MAG- 3 (Best for dynamic renal scintigraphy) → effective renal plasma flow

b) Static renal scintigraphy-

• Used for renal cortical mass & to locate functional renal mass.
• Tc- 99- DMSA is used for static scintigraphy.

Thyroid scintigraphy-

• Radiopharmaceuticals used in thyroid scanning are- ¹²³I, ¹³¹I, technetium- 99m pertechnate (as Tc 04).
• I¹²³ – 100- 300 μ curie dose
• I¹³¹ – 50- 100 μ curie dose

Parathyroid scintigraphy-

• Tc- 99 sestamibi (methoxyisobutylisonitrile, MIBI) is the scanning procedure of choice of parathyroid.
• Very sensitive to detect parathyroid adenoma and ectopic parathyroid.
• Tc- Thallium substraction scan was used.

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