EVALUATION OF BONE DISEASE
The traditional method to assess the number and extent of bone lesions in multiple myeloma is a skeletal survey (x-rays). Skeletal MRI and PET/CT scans are more sophisticated methods of imaging. MRI is usually superior to to PET/CT in detecting MM lesions, whereas PET/CT is usually more sensitive in assessing response to therapy.
International myeloma working group consensus statement and guidelines
regarding the current role of imaging techniques in the diagnosis and monitoring
of multiple Myeloma.
Leukemia. 2009 Sep;23(9):1545-56.
Dimopoulos M, Terpos E, Comenzo RL, Tosi P, Beksac M, Sezer O, Siegel D, Lokhorst H, Kumar S, Rajkumar SV, Niesvizky R, Moulopoulos LA, Durie BG; IMWG.
Contrast enhanced MRI and (18)F-FDG PET-CT in the assessment of multiple
myeloma: A comparison of results in different phases of the disease.
Eur J Radiol. 2012 Dec;81(12):4013-8.
Spinnato P, Bazzocchi A, Brioli A, Nanni C, Zamagni E, Albisinni U, Cavo M, Fanti S, Battista G, Salizzoni E.
This study retrospectively compared accuracy of MRI (210) and PET-CT scans (210) in the staging and follow-up of 191 patients with multiple myeloma. MRI performed better than PET-CT in staging and in patients with recurrent disease. PET-CT was superior in showing response to therapy, because normalization of findings was faster for PET-CT than MRI.
Bones should be evaluated with a complete skeletal radiographic survey,
- any symptomatic area
Skeletal radiographs show punched-out lytic lesions (lesions without reactive sclerosis of the surrounding bone), diffuse osteoporosis, and fractures. They are normal in 15-20% of patients. They are relatively insensitive: they don't detect osteolytic lesions unless >30% of trabecular bone is lost.
Plain x-rays can document disease progression by showing new lytic lesions or an increase in size of existing lesions. However, they are of little value in documenting disease remission, because lytic bone lesions rarely heal, even when patients are in complete remission. Moreover, new compression fractures may occur even in the absence of disease progression, due to osteopenia/osteoporosis or reduction of tumor mass.
Main limitations of plain x-rays:
- False negative results: bone lesions may be invisible in case of small size or early bone destruction
- Inaccurate visualization of some bones (e.g., sternum, ribs, scapulae)
- Not useful to assess response to therapy
Punched-out lytic bone lesions of the skull in patients with multiple myeloma (my personal archive):
X-ray of the right humerus, documenting a pathologic fracture due to multiple myeloma (my personal archive):
X-rays of the right femur in a patient with multiple myeloma. The left picture shows a lytic lesion involving the right proximal femural diaphysis. Endosteal scalloping is evident. She subsequently developed a pathologic fracture (right picture), which required surgical placement of an intramedullary nail (my personal archive):
Plain radiography may require additional and more sophisticated imaging, such as MRI or CT scans.
Main advantages of CT scans:
- It can detect small osteolytic lesions invisible at plain x-rays
- It allows accurate visualization of some bones (e.g., sternum, ribs, scapulae)
- It allows visualization of soft tissue masses extending from the bone lesions
- It helps planning surgery or radiation therapy
The following picture, taken from a patient with multiple myeloma, shows a shadow in the right mid-lung, but it does indicate whether the lesion originates in the lung parenchyma (as in lung cancer), or from the bone (my personal archive):
However, the CT scan in the same patient clearly demonstrates that the lesion originates from a rib (my personal archive):
Lytic lesions of a vertebral body and right sacral ala at CT scan (my personal archive).
A CT scan can be done with 3D image reconstructions. These may be useful to orthopedic specialists, when a pathologic fracture needs surgical intervention. The picture below shows plain radiographs and CT scans with 3D reconstructions of the left femur (my personal archive). In this case, the multiple myeloma produced a comminuted intertrochanteric fracture of the left femur.
The benefit of using whole-body, low-dose,
nonenhanced, multidetector computed tomography for follow-up and therapy
response monitoring in patients with multiple myeloma.
Cancer. 2007 Apr 15;109(8):1617-26.
Horger M, Kanz L, Denecke B, Vonthein R, Pereira P, Claussen CD, Driessen C.
This study evaluates the use of whole-body, low-dose, multidetector computed tomography (WBLD-MDCT) in 131 consecutive multiple myeloma patients. The authors found that WBLD-MDCT is a reliable imaging method for monitoring the course of MM.
Whole-body computed tomography versus conventional skeletal
survey in patients with multiple myeloma: a study of the International Myeloma
Blood Cancer J. 2017 Aug 25;7(8):e599.
Hillengass J, Moulopoulos LA, Delorme S, Koutoulidis V, Mosebach J, Hielscher T, Drake M, Rajkumar SV, Oestergaard B, Abildgaard N, Hinge M, Plesner T, Suehara Y, Matsue K, Withofs N, Caers J, Waage A, Goldschmidt H, Dimopoulos MA, Lentzsch S, Durie B, Terpos E.
Based on this study and other studies, the International Myeloma Working Group recommended that either CT or PET-CT should be the standard of care for the detection of osteolytic lesions in patients with multiple myeloma. The CT is more sensitive than the conventional skeletal survey (i.e., plain x-rays): CT identified lytic lesions in in 54 of 212 (25%) patients with negative skeletal survey, and in 12 of 66 (22%) patients with presumed smoldering myeloma.
Giampaolo Talamo, M.D.