PET/CT- und SPECT/CT-Diagnostik in der Onkologie – Wie kann die Strahlenexposition reduziert werden?

Zusammenfassung

Die Koregistrierung von CT-Daten im Rahmen nuklearmedizinischer Untersuchungen erlaubt eine direkte Korrelation anatomischer und funktioneller Informationen. Szintigrafische Befunde können so präzise lokalisiert und die Dignität unklarer CT-Befunde aufgrund funktioneller Daten beurteilt werden. Bei zahlreichen onkologischen Fragestellungen konnte eine Überlegenheit der Hybridtechnik gegenüber separat durchgeführter anatomischer und funktioneller Untersuchungen gezeigt werden. Die Einführung der PET/CT in die klinische Diagnostik hat aufgrund einer hohen diagnostischen Treffsicherheit zu einer Änderung des Diagnose-Algorithmus einiger solider Tumoren und hämatologischer Neoplasien geführt. Bezüglich SPECT/CT konnte eine verbesserte Diagnostik von Knochenmetastasen, neuroendokrinen Tumoren und von Wächterlymphknoten bei Erstdiagnose eines Mammakarzinoms oder malignen Melanoms belegt werden.

Die Anzahl der mittels Hybridgeräten durchgeführten Untersuchungen gehört zu den am schnellsten wachsenden unter den bildgebenden Verfahren in der Medizin. Mit zunehmender Untersuchungsfrequenz rückt die Minimierung der Strahlenexposition immer mehr in den Fokus und der Untersuchungsablauf wird kontinuierlich optimiert. Viele onkologische Fragestellungen können bereits mit einer ’low-dose´-PET/CT- oder -SPECT/CT-Untersuchung hinreichend beantwortet werden. Durch die Verwendung der neuesten Gerätetechnik kann die Strahlenexposition sowohl seitens der CT als auch durch die applizierte Aktivität der Radiopharmaka wesentlich beeinflusst werden. Dieser Artikel soll eine Übersicht über die mit Hybriduntersuchungen verbundene Strahlenexposition geben und zeigen, wie diese bereits heute signifikant reduziert werden kann. Entscheidend ist, dass ionisierende Strahlung nur bei eindeutigen klinischen Fragestellungen zum Einsatz kommen darf.

Abstract

Co-registration of CT data as part of nuclear medical imaging studies allows a direct correlation of anatomic and functional information. Scintigraphic findings can be precisely localized and lesions undefined at CT can be characterized based on functional properties. In a number of clinical scenarios, superiority of hybrid imaging over separately performed anatomically and functionally based imaging studies has been demonstrated. The introduction of PET/CT into the clinical diagnostics has led to a change of the diagnostic algorithm in a number of solid and hematological neoplasms, based on a higher diagnostic accuracy. Regarding SPECT/CT, a more precise diagnosis of bone metastases, neuroendocrine tumors and sentinel lymph node studies in patients with newly diagnosed breast cancer or malignant melanoma has been demonstrated.

In clinical medicine, hybrid techniques represent the most growing imaging modality. With increasing numbers of scans, minimization of radia­tion exposure becomes more relevant, leading to further optimization of the examination protocols. Many clinical questions can be sufficiently answered using ‛low-dose’ PET/CT- or SPECT/CT protocols. With the most recent scanner technology, radiation exposure can be markedly reduced. This applies to the CT component as well as to the administered activity of radiopharmaceuticals. This article reports on the radiation exposure caused by hybrid imaging and shows how further reduction is possible. It is most relevant to apply ionizing radiation only if there is a clear clinical indication.

Schlüsselwörter

PET/CT - SPECT/CT - Strahlenexposition - Onkologie - Hybridbildgebung

Key words

PET/CT - SPECT/CT - radiation dose - oncology - hybrid imaging

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