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Background/ObjectivesApparent diffusion coefficient (ADC) and signal intensity (SI) measurements play an increasing role in magnetic resonance imaging (MRI) of monoclonal plasma cell disorders. The purpose of this study was to assess interrater variability, repeatability, and reproducibility of ADC and SI measurements from bone marrow (BM) under variation of MRI protocols and scanners.Patients and MethodsFifty-five patients with suspected or confirmed monoclonal plasma cell disorder were prospectively included in this institutional review board–approved study and underwent several measurements after the standard clinical whole-body MR scan, including repeated scan after repositioning, scan with a second MRI protocol, scan at a second 1.5 T scanner with a harmonized MRI protocol, and scan at a 3 T scanner. For T1-weighted, T2-weighted STIR, B800 images, and ADC maps, regions of interest were placed in the BM of the iliac crest and sacral bone, and in muscle tissue for image normalization. Bland-Altman plots were constructed, and absolute bias, relative bias to mean, limits of agreement, and coefficients of variation were calculated.ResultsInterrater variability and repeatability experiments showed a maximal relative bias of −0.077 and a maximal coefficient of variation of 16.2% for all sequences. Although the deviations at the second 1.5 T scanner with harmonized MRI protocol to the first 1.5 T scanner showed a maximal relative bias of 0.124 for all sequences, the variation of the MRI protocol and scan at the 3 T scanner led to large relative biases of up to −0.357 and −0.526, respectively. When comparing the 3 T scanner to the 1.5 T scanner, normalization to muscle reduced the bias of T1-weighted and T2-weighted sequences, but not of ADC maps.ConclusionsThe MRI scanners with identical field strength and harmonized MRI protocols can provide relatively stable quantitative measurements of BM ADC and SI. Deviations in MRI field strength and MRI protocol should be avoided when applying ADC cutoff values, which were established at other scanners or when performing multicentric imaging trials.

Background In 2014, the diagnostic criteria for multiple myeloma were updated, leading to revised recommendations for imaging modalities and definition of therapy response. This review provides an overview of the current definitions of monoclonal plasma cell disease, diagnostic options, and changes relevant to radiologists. Method A pubmed search regarding the multiple myeloma guidelines was conducted, and results were filtered considering publications of international associations and expert reviews. Recommendations by the International Myeloma Working Group (IMWG), the National Comprehensive Cancer Network (NCCN, USA), the European Society for Medical Oncology (ESMO), and the European Myeloma Network are acknowledged. Results and Conclusion Conventional skeletal survey is to be replaced by cross-sectional imaging techniques. For initial diagnostics of bone lesions or bone marrow involvement defining multiple myeloma, whole-body low-dose CT and whole-body MRI are recommended. Two or more focal bone marrow lesions suspicious for myeloma on MRI will now define symptomatic disease even in the case of intact mineralized bone. Follow-up imaging is not clearly specified so far. New guidelines concerning the definitions of minimal residual disease include the assessment of focal lesions before and after treatment using 18F-FDG-PET/CT, with the potential to redefine the role of PET/CT in the diagnostics of multiple myeloma. Key points:  Citation Format

We sought to describe and compare material specific inflammatory and foreign body reactions after porcine liver embolization with spherical embolic agents. In 40 animals, superselective liver embolization was performed with four different spherical embolic agents of various sizes: 40-120 microm (Embozene, Embosphere), and 100-300 microm, 500-700 microm, and 700-900 microm (Embozene, Embosphere, Bead Block, and Contour SE, respectively). After 4 or 12 weeks, inflammatory reactions were evaluated microscopically according to the Banff 97 classification. For investigation of foreign body reactions, a newly designed giant cell score was applied. Banff 97 and giant cell scores closely correlated. At 4 weeks, small Embosphere particles (100-300 microm) had a significantly higher Banff 97 score than Embozene, Bead Block, and Contour SE of the corresponding size. After 12 weeks, the calculated differences were not statistically significant. Comparison between the 4-week results and the 12-week results revealed a statistically higher Banff 97 score for Embosphere 100-300 microm after 4 weeks than after 12 weeks (P = 0.02). The overall foreign body reaction was pronounced after embolization with smaller particles, especially in small Embosphere particles. Giant cell numbers with Embosphere 100-300 microm were statistically higher compared with the other materials of corresponding size (P < 0.0001). Inflammatory and giant cell reactions after embolization procedures depend on the embolic material. The overall inflammatory reaction was low. However, marked inflammation was associated with small Embosphere particles at 4 weeks, a finding that might be caused by the allogeneic overcoat. Correspondingly, giant cells indicating a foreign body reaction were more frequently associated with small particle sizes, especially after embolization with small Embosphere particles.

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