eMedicine Specialties > Radiology > Musculoskeletal

Multiple Myeloma: Imaging

Author: Steven M Sorenson, MD, Consulting Staff, Department of Radiology, Coast Radiology Imaging and Intervention
Coauthor(s): Amilcare Gentili, MD, Professor of Clinical Radiology, University of California at San Diego; Consulting Staff, Department of Radiology, Thornton Hospital; Chief of Radiology, San Diego VA Health Care System; Sulabha Masih, MD, Associate Professor of Diagnostic Radiology, University of California at Los Angeles; Consulting Staff, Department of Radiology, Section of Musculoskeletal Radiology, West Los Angeles Veterans Affairs Medical Center; Carol L Andrews, MD, Consulting Musculoskeletal Radiologist, Mink Radiologic Imaging; Consulting Staff, Department of Radiology, Antelope Valley Medical Center
Contributor Information and Disclosures

Updated: Aug 14, 2009

Radiography

Findings

The classic radiographic appearance of multiple myeloma is that of multiple, well-circumscribed, lytic, punched-out, round lesions within the skull, spine, and pelvis (see Images 1 and 3). The lesions tend to vary slightly in size. In addition, the bones of myeloma patients are, with few exceptions, diffusely demineralized. Because myeloma is a disease of the medullary compartment of the bone, more subtle lesions can be detected by the appearance of endosteal scalloping that is seen as slight undulation to the inner cortical margin of bone. This finding is suggestive of myelomatous involvement.

Although patients with advanced and extensive myeloma tend to have a number of circumscribed lytic lesions, some may simply have diffuse osteopenia on radiography. Fewer than 10% of patients present with a single myelomatous lesion, a plasmacytoma, found on radiographs (see Image 1). These lesions are bubbly expansions of a single bone, often the ribs or posterior elements of the spine, and are occasionally associated with a soft-tissue mass.

A rare form of myeloma known as POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) may demonstrate sclerotic lesions on radiographs, but this condition is responsible for fewer than 1% of myeloma cases. Radiographs of treated myeloma lesions may also show areas of abnormal bone architecture with sclerosis. Usually, little periosteal reaction is seen.

Degree of Confidence

As many as 79% of patients with myeloma demonstrate skeletal involvement. The finding of multiple lytic lesions on a skeletal survey involves 2 primary differential considerations, including myeloma and metastases. However, when these lesions are found together with bone marrow plasmacytosis and elevated blood gamma-globulins, the diagnosis of myeloma is certain. If tests for these 2 parameters have not been performed (ie, bone marrow plasmacytosis, blood gamma-globulins), the finding of multiple lytic lesions statistically represents widespread metastatic disease in 60-70% of patients, with the remainder representing myeloma. In diffuse osteopenia found on radiography, consider the diagnosis of myeloma and perform additional tests; however, most of these patients only have age-related osteoporosis.

False Positives/Negatives

Diffuse osteopenia that is found on radiographs is often a source of false-negative examinations because a substantial amount of cortex must be destroyed before it becomes visible radiographically.

False-positive examinations are encountered when multiple lytic lesions are found. In these patients, perform additional studies because the most likely source of this pattern is metastatic disease, not myeloma.

Computed Tomography

Findings

Computed tomography (CT) scanning depicts osseous involvement in myeloma. However the usefulness of this modality has not been well studied, and CT scanning is not required in most patients because the standard skeletal surveys usually depict most of the lesions that CT scans can detect.

The single clinical situation in which CT scan studies may be of value is in cases in which the patient has bone pain and a negative radiograph.¹⁴ In this scenario, demonstration of a myeloma lesion may alter therapy significantly. CT scanning can also guide percutaneous biopsies, especially of osseous or extraosseous lesions that are suspected of being plasmacytomas (see Image 13).

The literature also shows that the use of fluorine-18 fluorodeoxyglucose (¹⁸ F FDG) positron emission tomography (PET)/CT scanning can be helpful in the staging and post-therapeutic monitoring of multiple myeloma by providing functional detection of high metabolic lesions.^15,16 However, a preliminary report by Nanni et al in a small population of patients indicates that carbon-11 (¹¹ C)-choline PET/CT scanning may be more sensitive than¹⁸ F FDG PET/CT scanning for detecting myeloma lesions. The authors cautioned that more large-scale studies are needed to verify their results.¹⁶

Magnetic Resonance Imaging

Findings

MRI is potentially useful for imaging multiple myeloma because of this modality's superior soft-tissue resolution. The typical MRI appearance of a myeloma deposit is a round, low signal intensity (relative to muscle) focus on T1-weighted images, which becomes high in signal intensity on T2-weighted sequences. Images 5-7 demonstrate the appearance of a typical myeloma lesion in the proximal humerus. Myeloma lesions tend to enhance somewhat with gadolinium administration. In addition, diffuse areas of replacement of the normal fatty marrow may be seen, resulting in large regions of low T1-weighted signal.

Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans. 

NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving  or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape.

Degree of Confidence

Unfortunately, almost any musculoskeletal tumor has the same signal-intensity profile and enhancement pattern as myeloma. MRI, although sensitive to the presence of disease, is not disease specific. Additional tests must be employed to diagnose myeloma, such as measurement of gamma-globulin levels and direct aspiration of bone marrow to assess for plasmacytosis. Because of this, MRI may understage or overstage patients with myeloma.

In patients with extraosseous lesions, MRI may be useful to define the degree of involvement and to evaluate for cord compression.

Nuclear Imaging

Findings

Myeloma is a disease that results in overactivity of osteoclasts and the resultant liberation of bone. Nuclear medicine bone scans rely on osteoblastic activity (bone formation) for diagnosis. As such, historically, bone scans have underestimated the extent and severity of disease and have not been used routinely.¹⁷

However, a study by Erten et al appeared to demonstrate that whole-body scintigraphy with technetium-99m 2-methoxy-isobutyl-isonitrile (^99m Tc-MIBI) uptake scintigraphy may be a useful adjunct for the diagnostic imaging of multiple myeloma.¹⁸ The authors reported that^99m Tc-MIBI seemed to demonstrate the extent and intensity of bone marrow infiltration equally as well as MRI and suggested that^99m Tc-MIBI may serve as an alternative to MRI in cases in which MRI is not readily available or when its use is limited.

Degree of Confidence

The false-negative rate of bone scintigraphy in diagnosing multiple myeloma is high. Scans may be positive with normal radiographs, requiring another test for confirmation.

Angiography

Findings

Angiographic findings are nonspecific. Tumors may have a peripheral zone of increased vascularity. Generally, this technique is not used for the diagnosis of myeloma.

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