Role of Whole-Body Low-Dose CT in the Imaging of Plasma Cell Dyscrasias: Experience from an Indian Cohort

Lytic bone lesions are a hallmark of multiple myeloma (MM). Bone lesions in MM are detected by whole-body low-dose computed tomography (WBLD CT), now recommended over skeletal surveys by the International Myeloma Working Group due to higher sensitivity and better patient comfort. This retrospective study reviewed WBLD CT scans at our institute for patients of plasma cell dyscrasias (PCDs), assessing technique, radiation dose, bone lesions, and intramedullary soft tissue. It also correlated the imaging findings with laboratory parameters. This institutional review board-approved retrospective study included 118 patients with PCD who underwent a WBLD CT scan in our institute. Technical parameters were recorded. The computed tomography (CT) images were evaluated for osteolytic and medullary lesions. The imaging findings were correlated to laboratory parameters, including hemoglobin, calcium, creatinine, M-band, serum free light chains, plasma cell percentage, cytogenetics, β-2 microglobulin, and International Staging System (ISS)/Revised-ISS staging to predict bone involvement. There was no significant gender predilection in the distribution of lytic lesions or medullary soft tissue attenuation (p-value not significant). The scans were commonly performed at 110 kV and 50 mA. The arm position significantly affected the artifacts. The presence and distribution of lytic lesions and associated findings were studied. In addition, the medullary soft tissue density was also studied. Among the various clinical parameters correlated with lytic and medullary lesions, hypercalcemia was significantly associated with lytic lesions. This study of WBLD CT scans in suspected PCD patients in the Indian population provides insight into the imaging technique and radiation dose delivered. It also described the lytic lesions and medullary abnormalities and their distribution and correlation with clinical parameters, of which only hypercalcemia was statistically significant. The isolated presence of medullary soft tissue density in a few cases described in the study warrants the need for further correlation of these densities with magnetic resonance imaging or positron emission tomography-CT study, with the potential to establish medullary disease as a myeloma-defining event.