Radiotracers for SPECT brain imaging
Updates to Article Attributes
Radiotracers for SPECT brain imaging are divided into two classes: diffusiblesdiffusible and not-diffusible radiotracers; this distinction lies in the ability (or not) to cross the blood-brain barrier (BBB).
The not-diffusibles-diffusible radiotracers - composed of ions or polar molecules - are unable to cross the lipid double layer of cell membranes, their brain accumulation, therefore, is an indication of an altered BBB permeability, they are a classic.
Classic examples of this group:
- pertechnetate anion (99mTcO4-)
, -
99mTc-DTPA
, -
99mTc-sestaMIBI
, -
201Tl-chloride
, - 67Ga-citrate.
The diffusiblesdiffusible radiotracers, capable of crossing the blood-brain barrier by passive transport, are neutral, lipophilic and low molecular weight molecules. Depending on their localization mechanism, they can in turn be divided into two subclasses: perfusion and receptor-binding radiotracers.
Perfusion radiotracers are located in the brain tissue proportionally to the blood flow (e.g. 99mTc-HMPAO and 99mTc-ECD). Receptor-binding radiotracers (e.g. 123I-IBZM and 123I-ioflupane), instead, selectively interact with specific brain receptors (e.g. dopamine D2 and DaT, presynaptic dopamine transporters). Their distribution areis therefore greater in those areas of the brain that selectively express target receptors (e.g. nigrostriatal region).
-<p>Radiotracers for SPECT brain imaging are divided into two classes: diffusibles and not-diffusible radiotracers; this distinction lies in the ability (or not) to cross the blood-brain barrier (BBB).</p><p>The not-diffusibles radiotracers - composed of ions or polar molecules - are unable to cross the lipid double layer of cell membranes, their brain accumulation, therefore, is an indication of an altered BBB permeability, they are a classic examples: pertechnetate anion (<sup>99m</sup>TcO<sub>4</sub><sup>-</sup>), <sup>99m</sup>Tc-DTPA, <sup>99m</sup>Tc-sestaMIBI, <sup>201</sup>Tl-chloride, <sup>67</sup>Ga-citrate.</p><p>The diffusibles radiotracers, capable of crossing the blood-brain barrier by passive transport, are neutral, lipophilic and low molecular weight molecules. Depending on their localization mechanism, they can in turn be divided into two subclasses: perfusion and receptor-binding radiotracers.</p><p>Perfusion radiotracers are located in the brain tissue proportionally to the blood flow (e.g. <sup>99m</sup>Tc-HMPAO and <sup>99m</sup>Tc-ECD). Receptor-binding radiotracers (e.g. <sup>123</sup>I-IBZM and <sup>123</sup>I-ioflupane), instead, selectively interact with specific brain receptors (e.g. dopamine D2 and DaT, presynaptic dopamine transporters). Their distribution are therefore greater in those areas of the brain that selectively express target receptors (e.g. nigrostriatal region). <!--[if gte mso 9]><xml>- +<p>Radiotracers for SPECT brain imaging are divided into two classes: diffusible and not-diffusible radiotracers; this distinction lies in the ability (or not) to cross the blood-brain barrier (BBB).</p><p>The not-diffusible radiotracers - composed of ions or polar molecules - are unable to cross the lipid double layer of cell membranes, their brain accumulation, therefore, is an indication of an altered BBB permeability.</p><p>Classic examples of this group:</p><ul>
- +<li>pertechnetate anion (<sup>99m</sup>TcO<sub>4</sub><sup>-</sup>)</li>
- +<li> <sup>99m</sup>Tc-DTPA</li>
- +<li>
- +<sup>99m</sup>Tc-sestaMIBI</li>
- +<li>
- +<sup>201</sup>Tl-chloride</li>
- +<li>
- +<sup>67</sup>Ga-citrate.</li>
- +</ul><p>The diffusible radiotracers, capable of crossing the blood-brain barrier by passive transport, are neutral, lipophilic and low molecular weight molecules. Depending on their localization mechanism, they can in turn be divided into two subclasses: perfusion and receptor-binding radiotracers.</p><p>Perfusion radiotracers are located in the brain tissue proportionally to the blood flow (e.g. <sup>99m</sup>Tc-HMPAO and <sup>99m</sup>Tc-ECD). Receptor-binding radiotracers (e.g. <sup>123</sup>I-IBZM and <sup>123</sup>I-ioflupane), instead, selectively interact with specific brain receptors (e.g. dopamine D2 and DaT, presynaptic dopamine transporters). Their distribution is therefore greater in those areas of the brain that selectively express target receptors (e.g. nigrostriatal region). <!--[if gte mso 9]><xml>
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