Table 3.

Summary of the imaging recommendations of the IMWG [25] to establish the initial diagnosis and for the follow-up assessment of PCDs

	WBLDCT	WBMRI or MRI of the spine and pelvis
Imaging recommendations to establish the initial diagnosis
MGUS	To exclude MM in suspected high-risk non-IgM MGUS1	- Alternative, if CT is unavailable - Next step to evaluate equivocal findings of CT
SMM	Method of choice to detect osteolytic lesions**	To exclude focal lesions as myeloma-defining events, if CT is negative2
Solitary plasmacytoma	–	In solitary bone plasmacytoma3
MM	Method of choice to detect and evaluate the extend of osteolytic lesions4	Next step to exclude focal lesions as myeloma-defining events, if CT is negative and no other myeloma-defining event is present5
Imaging recommendations for follow-up examinations and the assessment of treatment response
MGUS	Not indicated unless signs of progression to symptomatic disease occur
SMM	- Repetition of same technique used at initial diagnosis at yearly intervals for at least 5 years depending on the risk factors - Additional alternating WBLDCT in cases with a high risk of progression to identify small osteolytic lesions
Solitary plasmacytoma	Repetition of same technique used at initial diagnosis at yearly intervals for at least 5 years
MM	- Repetition of same technique used at initial diagnosis to provide comparability - Follow-up imaging should be adapted in cases of progression, when the repeated and initially applied imaging technique does not reveal post-treatment imaging results that justify a change of treatment - WBLDCT when a relapse is suspected to evaluate the extent and dynamics of bone destruction as the most clinically relevant parameter6

Abbreviations: WBLDCT: whole-body low-dose computed tomography; WBMRI: whole-body magnetic resonance imaging; MGUS: monoclonal gammopathy of undetermined significance is a plasma cell dyscrasia in which plasma cells or other types of antibody-producing cells secrete a myeloma protein, i.e., an abnormal antibody, into the blood; this abnormal protein is usually found during standard laboratory blood or urine tests; SMM: smoldering multiple myeloma (also sometimes known as asymptomatic myeloma) is an early form of myeloma, which usually progresses to active myeloma, but at a slow rate. In smoldering myeloma, abnormal cells can be detected in the bone marrow, and abnormal protein can be detected in the blood and/or urine; MM: multiple myeloma

¹ Additional PET/CT if WBLDCT is positive

² PET/CT can be used as an alternative to WBLDCT and instead of WBMRI if the latter is unavailable or in cases with specific contraindications

³ PET/CT in patients with solitary extramedullary plasmacytoma and as an alternative in solitary bone plasmacytoma, if MRI is unavailable

⁴ PET/CT can be used as an alternative to WBLDCT

⁵ PET/CT can be used as an alternative to MRI if the latter is unavailable or in cases with specific contraindications, and it is the preferred imaging method to generate a baseline for follow-up assessments

⁶ Yearly follow-ups are recommended for patients with residual lesions detected by PET/CT because of the high risk of early progression