Standardized uptake value

The abbreviation SUV stands for ' standardized uptake value' and is used in positron emission tomography for the quantification of regional physiological radioactivity concentrations. The SUV value describes - for example, when using the tracer FDG - glucose metabolism of a tumor quantitatively. The SUV is the ratio of the injected activity and calculated as follows:

SUV = activity concentration [ Bq / ml] * scale value / administered activity [ Bq ].

The normalization value includes the physical device parameter correction ( attenuation correction, scattered radiation correction, dead-time, and others) and the following patient- or investigation -specific information: radionuclide used (due to the decay correction ), patient weight, size of the patient, activity of the full syringe activity the empty syringe injection timing and time of the time of measurement of the empty syringe.

For interindividual comparison, the activity either on body weight (body weight, BW [g ] ), the fat-free body mass ( lean body mass, LBM [ kg] ) or on the body surface (body surface area, BSA [ m ] ) is normalized. For equal distribution of radioactivity is an SUV value of 1, values ​​greater than one results describe an enrichment, values ​​smaller than one depletion. As a tracer in the body is not equally distributed, are in healthy tissue usually values ​​between 1 and 2 prior - if there is no physiological enrichment takes place such as in the brain, heart, kidney, and bladder or hardly FDG is to be found, such as in adipose tissue or in cysts ( see figure). The SUV value is an aid in the differentiation between malignant ( malignant ) and benign ( benign ) tissue; in tumors are values ​​prior to about 20, but he is subject to a number of factors:

  • Lesion or ROI shape and size: small lesions ( <1 cm ) have due Partialvolumenartefakten the scanner for high measurement uncertainties.
  • Measuring time: Although the normalization value of radioactive decay is taken into account, the accumulation in the lesion is not constant over time due to their pharmacokinetics. If two measurements to be comparable, it must be ensured that both measurements at the same time after injection of the tracer took place.
  • Blood sugar levels of patients: high blood sugar levels FDG is less strongly accumulated.
  • Weight and fat percentage of patients.
  • Scanner design: the quality of the physical correction of the measured signals as well as the spatial resolution of clinical PET scanners is different (manufacturer, type and age of the unit) and has a marked influence on the amount and uncertainty of the determined SUV value.
  • Selected image reconstruction method (FBP or iterative) and the parameters of the image reconstruction.
  • Physiological movement of the lesion: A metastasis that is, for example, in the apex of the lung or in the liver, sometimes moved by the respiratory motion of the patient during the recording of several centimeters, the recording time (1-3 minutes ) exceeds the maximum breath-hold time. The measured uptake is therefore in the " smeared " - similar to a blur in photography. This can cause a lesion can not be recognized as such. Some newer PET scanners have a so-called respiratory triggering, in this disturbing influence can be largely eliminated.

For these reasons, the SUV value in the first place it is advisable to describe the course of therapy or the response (response) therapy. In this case, some of the above-mentioned influencing parameters remain constant during the measurements, or can be kept constant.

Swell

  • Bernd J. Krause, Andreas K. Buck, Markus Schwaiger: Nuclear Medical Oncology. In: ecomed Medicine ( c) 2007, ISBN 978-3-609-76308-8, pp. 56ff
  • Sally F. Barrington, Michael N. Maisey and Richard L. Choice: Atlas of Clinical Positron Emission Tomography. Second Edition. Hodder Arnold, 2006, ISBN 0-340-81693-7, pp. 24 and 25
  • Manual of the GE Advantage Workstation, version 4.4
  • Metabolism
  • Nuclear Medicine
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