Bone Metastases Are Measurable: The Role of Whole-Body MRI and Positron Emission Tomography

Abstract

Metastatic tumor deposits in bone marrow elicit differential bone responses that vary with the type of malignancy. This results in either sclerotic, lytic, or mixed bone lesions, which can change in morphology due to treatment effects and/or secondary bone remodeling. Hence, morphological imaging is regarded unsuitable for response assessment of bone metastases and in the current Response Evaluation Criteria In Solid Tumors 1.1 (RECIST1.1) guideline bone metastases are deemed unmeasurable. Nevertheless, the advent of functional and molecular imaging modalities such as whole-body magnetic resonance imaging (WB-MRI) and positron emission tomography (PET) has improved the ability for follow-up of bone metastases, regardless of their morphology. Both these modalities not only have improved sensitivity for visual detection of bone lesions, but also allow for objective measurements of bone lesion characteristics. WB-MRI provides a global assessment of skeletal metastases and for a one-step “all-organ” approach of metastatic disease. Novel MRI techniques include diffusion-weighted imaging (DWI) targeting highly cellular lesions, dynamic contrast-enhanced MRI (DCE-MRI) for quantitative assessment of bone lesion vascularization, and multiparametric MRI (mpMRI) combining anatomical and functional sequences. Recommendations for a homogenization of MRI image acquisitions and generalizable response criteria have been developed. For PET, many metabolic and molecular radiotracers are available, some targeting tumor characteristics not confined to cancer type (e.g. 18F-FDG) while other targeted radiotracers target specific molecular characteristics, such as prostate specific membrane antigen (PSMA) ligands for prostate cancer. Supporting data on quantitative PET analysis regarding repeatability, reproducibility, and harmonization of PET/CT system performance is available. Bone metastases detected on PET and MRI can be quantitatively assessed using validated methodologies, both on a whole-body and individual lesion basis. Both have the advantage of covering not only bone lesions but visceral and nodal lesions as well. Hybrid imaging, combining PET with MRI, may provide complementary parameters on the morphologic, functional, metabolic and molecular level of bone metastases in one examination. For clinical implementation of measuring bone metastases in response assessment using WB-MRI and PET, current RECIST1.1 guidelines need to be adapted. This review summarizes available data and insights into imaging of bone metastases using MRI and PET.

Combining Deep Learning and Radiomics for Automated, Objective, Comprehensive Bone Marrow Characterization From Whole-Body MRI

“…The value of wb-MRI for bone (marrow) diagnostics in oncologic settings has been demonstrated in numerous studies, 1,26 and wb-MRI is now recommended for imaging across entities as MM, 22,27 advanced prostate cancer, 28,29 and for cancer screening 30 . An increasing amount of automatic segmentation algorithms for wb-MRIs has been developed 31–33 .…”

“…The value of wb-MRI for bone (marrow) diagnostics in oncologic settings has been demonstrated in numerous studies, 1,26 and wb-MRI is †Refers to the number (and percentage compared with overall number of respective cohort) of patients having skeletal implants as for example hip or knee endoprosthesis or spinal fusion.…”

Early circulating tumorDNAdynamics as a pan‐tumor biomarker for long‐term clinical outcome in patients treated with durvalumab and tremelimumab

“…These two patients were categorized as PD due to the appearance of new bone and lung lesions upon evaluation; the target lesions for T086 were evaluated as PR, and T101 was unable to be assessed by recist version 1.1 criteria because of lack of qualifying target lesions. These patients may represent a setting in which ctDNA assessment can aid in interpretation of challenging or mixed radiologic response [ 28 ].…”

Early Imaging to Detect Bone Metastatic Disease of a 54-Year-Old Woman with History of Breast Cancer: A Case Report

“…Bone is a common site of secondary tumor deposits because in its rigid, calcified, outer cortex, it has a richly vascular inner marrow of bony trabeculae, stroma, haematopoeitic tissue and fat [8]. The incidence of bone metastases is 65-75% in advanced metastatic breast cancer, 65-75% in prostate cancer, 60% in thyroid cancer, 30-40% in lung cancer, 40% in bladder cancer, 20-25% in renal cell carcinoma and 14-45% in melanoma [8]. In breast cancer, estrogen influences the bone microenvironment by creating and conditioning a favorable niche for colonization of breast cancer cells [8].…”

“…The incidence of bone metastases is 65-75% in advanced metastatic breast cancer, 65-75% in prostate cancer, 60% in thyroid cancer, 30-40% in lung cancer, 40% in bladder cancer, 20-25% in renal cell carcinoma and 14-45% in melanoma [8]. In breast cancer, estrogen influences the bone microenvironment by creating and conditioning a favorable niche for colonization of breast cancer cells [8]. In this study, a 54-year-old Indonesian womanhas a medical history of breast cancer and has complaint of hip pain.Heightened awareness in the primary care setting of possible metastatic bone disease is essential in patients who present with musculoskeletal pain and a history of cancer or previous radiotherapy [9].…”