Whole-body MR or PET-CT?

Abstract

Breast cancer is the most frequent malignancy and most common cause of cancer-related death in women worldwide with approximately 500,000 deaths each year [1]. Approximately 10–20% of all patients diagnosed with breast cancer will develop tumor recurrence at some time within the course of their disease. Therefore, early diagnosis and accurate restaging of recurrent breast cancer is important to define appropriate therapeutic strategies or to identify patients with limited disease who potentially could benefit from curative treatment. The basic strategy in the follow-up of breast cancer to date consists of regular mammography and clinical examinations as well as symptomorientated multi-modal imaging strategies [2]. This procedure by large is based on assumptions from studies performed in the early 90’s, that an intensified after-care does not necessarily correlate with an increased survival benefit [3,4]. Unfortunately, this approach mainly comprises modalities with known poor sensitivity (e.g. chest radiographs), examinations with examinerdependent variation of sensitivity (e.g. abdominal ultrasound) or procedures with limited specificity, like bone scintigraphy [5, 6]. In the last 10 years numerous promising concepts have been developed for the therapy of metastasized breast cancer, including hormonal drugs and immune therapy, which indicate an improvement in patients’ progression-free survival [6–8]. New surgical and interventional techniques for the management of limited disease have demonstrated its effectiveness and reported promising survival rates [8,9]. Against this background, whole-body imaging modalities, such as fluorodeoxyglucose positron emission tomography (FDG-PET)-CT or whole body-MRI (WB-MRI) appear as new promising tools to detect tumor recurrence with high accuracy and to provide more effective therapeutic strategies to the patient. It has been reported that whole-body fluorodeoxyglucose (FDG)positron emission tomography (PET) is of clinical value in the search for breast cancer metastases, especially when suggested by the presence of clinical symptoms or by a progressive increase in biochemical markers [9,10]. The combination of metabolic data from PET with the detailed anatomical information of multi-slice computed tomography as dual-modality scanners has markedly increased lesion localization and diagnostic accuracy compared to both modalities as standalone applications [11,12]. Recently, combined PET-CT has been introduced as a whole-body imaging modality for screening of patients with suspicion of recurrent breast cancer, indicating an improved restaging accuracy and possible impact on therapy [13].