Longitudinal Monitoring of Apparent Diffusion Coefficient May Classify Disease Activity in Multiple Myeloma

Longitudinal monitoring of apparent diffusion coefficient (ADC) values in patients with multiple myeloma (MM) may classify disease activity in some instances, according to a study published in the European Journal of Radiology.

In this retrospective analysis, researchers assessed whole-body magnetic resonance imaging (MRI) data in patients with stage III MM who were undergoing systemic treatment at the time of analysis. They evaluated bone marrow (BM) involvement using a standardized protocol and measured ADC values in focal lesions (FL) and diffusely involved BM (DIBM) regions. The researchers performed four MRI examinations: the first at baseline (mean, three months), the second at a mean 10 months, the third at a mean 18 months, and the last during a follow-up. Overall, patients were classified into two groups: responders (n=59) and non-responders (n=34).

According to the results, a subgroup of patients with MM undergoing short-term first follow-up experienced a notable increase in ADC in responders (P=0.001) but not non-responders (P=0.9). The researchers observed that ADC levels continually dropped in responders (P=0.02) and increased slightly in non-responders (P=0.8). Moreover, in patients with DIBM, ADC values decreased in responders (P<0.001) and non-responders (P=0.78). The researchers noted that an ADC cutoff value of 0.5-0.6×103 mm2/s for diagnosing inactive disease at follow-up proved unreliable.

In [patients with MM] with lower tumor burden, the longitudinal course of ADC values is predictable only for FL whereas for DIBM ADC changes considerably overlap between responders and non-responders and are not indicative for assessment of the disease activity,” the researchers concluded.