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Imaging


Advances in imaging multiple myeloma


Advanced imaging techniques have changed clinical practice in multiple myeloma significantly. This article discusses (dis-) advantages of the currently available modalities and debates which method is appropriate for imaging certain stages of disease


Maximilian Merz MD Jens Hillengass MD Department of Hematology, Oncology and Rheumatology, University Hospital of Heidelberg; Department of Radiology, German Cancer Research Center, Heidelberg, Germany


Multiple myeloma (MM) is characterised by infiltration and proliferation of malignant plasma cells in the bone marrow which consecutively leads to disease defining end-organ damages including hypercalcaemia, renal insufficiency, anaemia and osteolytic bone lesions (CRAB criteria).1


Because


occurrence of osteolyses is the most common reason to start systemic chemotherapy, imaging is a cornerstone in the clinical management of patients suffering from MM. Clinicians are nowadays challenged by the growing variety of imaging modalities available for the diagnosis, initial staging and follow- up of patients with MM. Furthermore, radiological assessment is no further restricted to identification of osteolyses in order to discriminate between symptomatic and asymptomatic patients, but also includes assessment of precursor diseases such as monoclonal gammopathy of undetermined significance (MGUS) and smoldering MM (SMM). This article clarifies the advantages and disadvantages of the currently available imaging modalities and provides a guideline for imaging each individual stage of disease.


Skeletal survey 12 Approximately 40 years ago, Salmon and www.hospitalpharmacyeurope.com


Durie proposed one of the first, and currently still appreciated, clinical staging systems that is – among others – based on the identification of osteolytic lesions on skeletal survey.2


The skeletal survey


comprises conventional X-rays of the skull, spine, pelvis and chest, as well as the humeri and femora. Due to its widespread availability, low costs and limited radiation exposure compared with computed tomography (CT), skeletal survey is still recognised in the current guidelines by the International Myeloma Working Group (IMWG) as the imaging modality of choice for initial work-up of MM patients if low-dose CT is not available.3


However, in our and many


colleagues’ clinical practice, the skeletal survey has been replaced by CT because of its many disadvantages4


: most


importantly, conventional X-ray films are not very sensitive in detecting osteolyses. Up to 50% of cortical bone needs to be already destroyed before an osteolysis is visible on skeletal survey.5


Furthermore,


regions such as the spine or pelvis are difficult to assess because of superimposition artifacts. Second, specificity of skeletal survey is limited: benign lesions, such as osteoporotic fractures or bone resorption induced by chronic inflammation, cannot be delineated from lesions caused by malignant plasma cell infiltration.5


fractures of the extremities in the emergency room setting.


CT


Compared with skeletal survey, CT offers the opportunity to identify even the smallest osteolyses, in every anatomic region without any influence by superimposition of surrounding bony or soft tissue. Therefore, several studies have shown that CT has a higher sensitivity in detecting osteolyses compared with conventional X-ray.6


Furthermore, the


implementation of low-dose protocols and the introduction of multidetector CT allow fast whole-body imaging with reasonable radiation exposure. Another advantage of CT compared with skeletal survey is the generation of three- dimensional datasets: multidisciplinary management of MM patients often includes consultation of orthopaedics and radiation oncologists. CT enables the evaluation of stability beyond two- dimensional assessment of long bones7 – most importantly in the axial skeleton. Additionally, approaches such as intensity-modulated radiation therapy depend on three-dimensional datasets for treatment planning.8


Lastly, CT does not Lastly,


skeletal surveys are not suitable for follow-up of patients with MM because improvement in osteolyses – even in the era of novel agents – rarely occur after treatment. In our practice, conventional X-rays only retain their importance when it comes to the diagnosis of pathological


only exhibit higher sensitivity compared to X-ray when it comes to detection of osteolyses but also the assessment of intramedullary lesions in the long bones, because there the myeloma infiltrates show a contrast to the surrounding fatty bone marrow.9


or remission. Therefore – in


Imaging the occurrence or


regression of such intramedullary lesions is a radiological surrogate for progressive disease10


contrast to skeletal survey – CT enables to


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