Monitoring the response of bone metastases to treatment with Magnetic Resonance Imaging and nuclear medicine techniques: A review and position statement by the European Organisation for Research and Treatment of Cancer imaging group

Abstract

Assessment of the response to treatment of metastases is crucial in daily oncological practice and clinical trials. For soft tissue metastases, this is done using computed tomography (CT), Magnetic Resonance Imaging (MRI) or Positron Emission Tomography (PET) using validated response evaluation criteria. Bone metastases, which frequently represent the only site of metastases, are an exception in response assessment systems, because of the nature of the fixed bony defects, their complexity, which ranges from sclerotic to osteolytic and because of the lack of sensitivity, specificity and spatial resolution of the previously available bone imaging methods, mainly bone scintigraphy. Techniques such as MRI and PET are able to detect the early infiltration of the bone marrow by cancer, and to quantify this infiltration using morphologic images, quantitative parameters and functional approaches. This paper highlights the most recent developments of MRI and PET, showing how they enable early detection of bone lesions and monitoring of their response. It reviews current knowledge, puts the different techniques into perspective, in terms of indications, strengths, weaknesses and complementarity, and finally proposes recommendations for the choice of the most adequate imaging technique.

18F-Fluoride PET Used for Treatment Monitoring of Systemic Cancer Therapy: Results from the National Oncologic PET Registry

“…To date, however, relatively little information is available about the impact of NaF PET on clinical decision making when used to assess the biologic response of osseous metastatic disease to guide continuing, switching, or stopping systemic therapy (28,32). Since 2011, NaF PET has been available for Medicare beneficiaries in the United States under Coverage with Evidence Development, thereby providing an opportunity to assess how NaF PET is being used in clinical practice for patients with osseous metastases.…”

“…Assessing osseous metastasis is particularly challenging because bone lesions are generally considered to be nonmeasurable by anatomic imaging. Accordingly, functional imaging approaches may be more useful in patients with bone-dominant disease (27,28). Standards for interpreting such studies are under development; for example, new guidelines for response assessment by conventional BS in patients with metastatic prostate cancer define progression as 2 or more new lesions on 2 subsequent treatment monitoring scans (2,29,30), and the MD Anderson Cancer Center response criteria in bone-only metastatic breast cancer do not yet include 18 F-FDG PET or NaF PET (27,31).…”

Management of patients with advanced prostate cancer: recommendations of the St Gallen Advanced Prostate Cancer Consensus Conference (APCCC) 2015

“…recognition of disease response, stability or progression and not only late confirmation of progression) and its potential impact on the sequential use of agents with a proven overall survival benefits [68,[75][76][77][78].…”

Imaging Bone Metastases in Breast Cancer: Staging and Response Assessment

“…The signal from diffusion-weighted MRI (DW-MRI) depends on the rate of diffusion of water molecules, whereby tumors-which are typically hypercellular-show restricted diffusion compared with normal tissues. This property can be quantified, with the apparent diffusion coefficient representing the rate of signal loss with increasing diffusion weighting (73,74). The apparent diffusion coefficient typically increases with successful therapy as a result of cytotoxicity, reduced cellularity, and loss of cell membrane integrity, allowing water molecules to be more freely diffusible.…”