Serum Levels of Carboxy-terminal Telopeptide of Type-I Collagen Are Elevated in Patients with Multiple Myeloma Showing Skeletal Manifestations in Magnetic Resonance Imaging but Lacking Lytic Bone Lesions in Conventional Radiography

Purpose: Skeletal involvement is a hallmark of multiple myeloma. Increased bone resorption can even be present in patients lacking osteolyses in conventional radiography. Magnetic resonance imaging (MRI) of the spine was established as a more sensitive technique to depict bone abnormalities. Type-I collagen degradation product carboxyterminal telopeptide of type-I collagen (ICTP) was introduced as a novel biochemical parameter reflecting the bone resorption activity in myeloma. The aim of this study was to evaluate whether increased ICTP serum levels predict abnormal MRI patterns in myeloma patients. Experimental design: MRI of the spine was performed in 32 untreated patients with multiple myeloma, who had no skeletal abnormalities in conventional radiographies. Simultaneously, ICTP was measured in serum by a competitive radioimmunoassay at corresponding time points. Results: Serum ICTP was significantly ( P = 0.002) elevated in patients with abnormal bone MRI compared with those patients with normal MRI findings. The sensitivity of ICTP for depiction of MRI abnormalities was 79%; the positive and negative predictive values were 85 and 84%, respectively. Compared with ICTP, the parameters of disease activity, β2-microglobulin and C-reactive protein, had a much lower sensitivity for abnormal MRI (29 and 64%, respectively). Conclusions: In myeloma patients without osteolytic lesions in conventional radiography, abnormal skeletal MRI is accompanied by an increase in serum levels of ICTP. Our data show that ICTP can be used as an inexpensive parameter to identify myeloma patients with normal skeletal survey who have a high probability of skeletal involvement and deserve more accurate diagnostic evaluation using MRI.