Radionuclide angiography

The Radionuklidangiografie is a nuclear medicine diagnostic procedures in angiology , which vessels scintigraphy are presented. A distinction must be made between examinations of the arteries (radionuclide arteriography) , the veins (radionuclide phlebography) and the lymphatic vessels (lymph scintigraphy) .

Procedure

Radionuclide angiography as part of a 3-phase skeletal scintigraphy . Dynamic images of the chest and neck; one image every 2 seconds. The tracer flows via the left subclavian vein into the right ventricle (Fig. 7–8), the lungs (Fig. 9–10), the left ventricle (Fig. 13–14) into the large arteries ( subclavian artery on both sides, common carotid artery on both sides , Abdominal aorta ; Figs. 15–16 to 23–24). Note small tracer traces on individual venous valves of the subclavian vein up to about Fig. 45–46. No noticeable increased blood flow in the right shoulder region. (Clinical question: osteomyelitis ?)

Radionuclide Arteriography

The procedure has largely been abandoned and is no longer presented in more recent nuclear medicine textbooks. Today (as of 2009) the arteries are usually examined using digital subtraction angiography , magnetic resonance angiography or duplex sonography .

The arterial perfusion (blood flow) is still shown today as part of a three-phase skeletal scintigraphy and used diagnostically by comparing the arterial flow of the tracer (usually a bisphosphonate marked with ^99m Tc ) after intravenous administration . With larger vessels, the scintigram can be assessed visually ("with the naked eye"). In the case of smaller vessels or entire river areas, the region of interest technique (ROI technique) is also used, in which time- activity curves are assessed as functional scintigraphy.

In a Blutpoolszintigrafie the most with can possibly already in the phase of arterial inflow ^99m labeled Tc red blood cells ( erythrocytes ) a circulation are detected.

Radionuclide phlebography

Both radionuclide phlebography and the previously much more common venography as an X-ray method have largely been replaced by duplex sonography .

One possible application of radionuclide phlebography is if the presence of a thrombosis is suspected , particularly in the leg veins, but also in the arm veins. For this purpose, technetium-marked macro- colloids or albumin particles, for example, are injected into a congested vein of the affected extremity . With rapid scintigraphic images of the venous outflow, depots of the tracer can be displayed, which indicate a local outflow delay. The blood clot itself ( thrombus ) does not show itself with this method. A lung perfusion scintigraphy can be followed without further radiation exposure .

For the scintigraphic display of blood clots themselves, thrombocytes marked with ¹¹¹ In can be used. Disadvantages of the method are the relatively high radiation exposure and the time required (at least two days). However, therapeutic decisions usually have to be made more quickly. Duplex sonography is therefore usually used to detect thrombi in the area of ​​the peripheral veins, and echocardiography or magnetic resonance tomography are usually used to detect thrombi in the heart .

Lymph scintigraphy

Indications for the scintigraphic representation of the lymph vessels result from suspicion of a unilateral lymphatic drainage disorder of an extremity , for the detection of lymphoceles and for the representation of the patency of lymph vessel transplants . For this purpose, microcolloids labeled with ^99m Tc are usually injected inside (intra-) or below the skin (subcutaneous), for example in the folds of skin between fingers or toes. Scintigraphic images over the next 20 minutes to 3 hours show the lymph vessels , collectors and nodes in the drainage area. The examination can be carried out with movement or muscle work, if necessary also in side comparison.

The lymphatic vessels in the downstream area of ​​a malignant tumor are also often shown in the scintigraphy of the sentinel lymph node .

Contraindications

A pregnancy is considered, with few exceptions as an absolute contraindication for nuclear medicine examinations, breast-feeding as a relative contraindication. After a scintigraphy with ^99m Tc, the breastfeeding woman should express and discard the milk for 48 hours.

Radiation exposure

When assessing radiation exposure , it should be noted that the assessment of the vessels usually takes place as part of an already indicated scintigraphy, i.e. no additional radiation is used.

For a skeletal scintigraphy with 500 MBq ^99m Tc- DTPA 2.6 mSv are given, for a blood pool scintigraphy with 750 MBq ^99m Tc-labeled erythrocytes 7.4 mSv. The radiation exposure for a lung scintigraphy with 200 MBq ^99m Tc colloid is about 1.9 mSv, with a thrombocyte scintigraphy with 15 MBq ¹¹¹ In 7.8 mSv. Lymph scintigraphy with 100 MBq ^99m Tc colloid has a radiation exposure of about 1 mSv.

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• U. Büll and M. Schwaiger. Heart, circulation, blood vessels. In: Büll, Schicha, Biersack, Knapp, Reiners, Schober (eds.). Nuclear medicine. Stuttgart, New York 2001 ISBN 3-13-128123-5

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