|ECR 2015 / C-0664|
|Value of bimodal 18F-Choline-PET/MRI and trimodal 18F-Choline-PET/MRI/TRUS for the assessment of prostate cancer recurrence after radiation therapy and radical prostatectomy|
|This poster is published under an open license. Please read the disclaimer for further details.|
Radical prostatectomy (RP) and radiation therapy (RT) are well-established primary therapeutic options in the management of prostate cancer (PCa).
Despite technical improvements,
there is still a considerable risk of cancer recurrence after therapy.
27-53% of all patients undergoing radical prostatectomy (RP) or radiation therapy (RT) develop prostate-specific antigen (PSA) recurrence (biochemical recurrence) .
In PCa patients with a clinical suspicion of recurrence, imaging plays a pivotal role in distinguishing between local recurrence and metastatic disease (i.e. lymph-node and skeletal metastases), with important implications in the therapeutic management of patients [2, 3]. Digital rectal examination and transrectal ultrasound (TRUS) are neither sensitive nor specific in detecting local recurrences after RP and RT . While bone scintigraphy and contrast enhanced abdominopelvic computed tomography (ceCT) are commonly used to detect metastatic disease, their diagnostic yield has been proven to be low in patients with a PSA level <10 ng/mL . By means of newer imaging techniques, systemic disease can be detected at lower PSA values and when there are fewer metastases [2, 3].
At present, the most promising tools for assessing PCa patients with biochemical recurrence are multiparametric Magnetic Resonance Imaging (mpMRI) and Positron Emission Tomography (PET)/Computed Tomography (CT) with radio-labeled choline derivatives . In mpMRI, morphological T2-weighted (T2w) sequences are combined with functional MRI techniques, including diffusion weighted imaging (DWI), dynamic contrast enhanced (DCE) perfusion imaging and spectroscopy, the latter requiring the use of dedicated endorectal coils . MRI can also detect skeletal metastases with excellent diagnostic accuracy, since it identifies metastatic changes in the hematopoietic bone marrow before osteoblastic reaction [7-9]. However, it performs poorly in the identification of pelvic lymph node metastases [3-10]. Choline-PET/CT is a powerful whole-body tool for the restaging of biochemically recurrent PCa, in particular in those patients in whom the other imaging techniques have failed to identify the site of recurrence [2, 3, 9]. Limitations of choline-PET/CT are its low spatial resolution, with insufficient delineation of pelvic anatomy, and a poor detection rate for PCa recurrence when PSA values are <1 ng/mL [3, 4, 9]. Multimodal fusion imaging enables morphological, functional and metabolic information from different modalities to be combined, thus improving the diagnostic performance and overcoming the peculiar limitations of each separate modality [11-13]. This multimodal combined approach has great potential in the assessment of biochemical recurrence after PCa treatment . New combined PET/MRI scanners provide simultaneous acquisition of both imaging modalities by performing an automated coregistration process with perfect temporal correlation of dynamically acquired datasets and MRIbased attenuation correction. However, these expensive systems are not widely available and are mainly limited to research facilities [14-17]. By contrast, multimodal fusion imaging software platforms allow the co-registration of different imaging datasets acquired at different times [9, 11].
A recent study, in which bimodal 18F-choline-PET/MRI fusion imaging was used to assess a cohort of 21 PCa patients with biochemical recurrence after external beam RT, yielded very encouraging results .
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