Quantitative and qualitative assessment of plasma cell dyscrasias in dual-layer spectral CT.

OBJECTIVES: Virtual non-calcium (VNCa) images could improve assessment of plasma cell dyscrasias by enhancing visibility of bone marrow. Thus, VNCa images from dual-layer spectral CT (DLCT) were evaluated at different calcium suppression (CaSupp) indices, correlating results with apparent diffusion coefficient (ADC) values from MRI. METHODS: Thirty-two patients with initial clinical diagnosis of a plasma cell dyscrasia before any chemotherapeutic treatment, who had undergone whole-body low-dose DLCT and MRI within 2 months, were retrospectively enrolled. VNCa images with CaSupp indices ranging from 25 to 95 in steps of 10, conventional CT images, and ADC maps were quantitatively analyzed using region-of-interests in the vertebral bodies C7, T12, L1-L5, and the iliac bone. Independent two-sample t-test, Wilcoxon-signed-rank test, Pearson's correlation, and ROC analysis were performed. RESULTS: Eighteen patients had a non-diffuse, 14 a diffuse infiltration in conventional MRI. A significant difference between diffuse and non-diffuse infiltration was shown for VNCa-CT with CaSupp indices from 55 to 95, for conventional CT, and for ADC (each p < 0.0001). Significant quantitative correlation between VNCa-CT and MRI could be found with strongest correlation at CaSupp index 65 for L3 (r = 0.68, p < 0.0001) and averaged L1-L5 (r = 0.66, p < 0.0001). The optimum CT number cut-off point for differentiation between diffuse and non-diffuse infiltration at CaSupp index 65 for averaged L1-L5 was -1.6 HU (sensitivity 78.6%, specificity 75.0%). CONCLUSION: Measurements in VNCa-CT showed the highest correlation with ADC at CaSupp index 65. VNCa technique may prove useful for evaluation of bone marrow infiltration if MRI is not feasible. KEY POINTS: • VNCa-CT images can support the evaluation of bone marrow infiltration in plasma cell dyscrasias. • VNCa measurements of vertebral bodies show significant correlation with ADC in MRI. • Averaging L1-L5 at CaSupp index 65 allowed quantitative detection of infiltration comparable to MRI ADC.

[Extranodal abdominal lymphomas]. / Extranodale abdominale Lymphomerkrankungen.

BACKGROUND: Extranodal manifestations occur in up to 40% of non-Hodgkin lymphomas. The prevalence of extranodal involvement has increased. OBJECTIVES: A comprehensive overview on lymphoma involvement in the parenchymatous abdominal organs, the gastrointestinal tract, and the peritoneal cavity under due consideration of clinical implications is given. MATERIALS AND METHODS: A selective literature search with analysis of dedicated original research articles and reviews was carried out. Clinical guidelines are discussed. RESULTS: Extranodal abdominal lymphoma involvement usually occurs secondarily in advanced disease. Sites involved most frequently are the liver and the gastrointestinal tract. Extranodal abdominal lymphoma involvement is more common in the immunocompromised patient. CONCLUSION: Imaging findings of extranodal abdominal lymphoma are variable. Lymphoma is an important differential diagnosis to be considered in unclear tumor diseases.