Patients and control group
This retrospective analysis included 18 MS patients (female, n=8 [44; median age 63 years, range 45–86). Detailed demographic and SM-associated disease characteristics are presented in Tables 1 and 2. Eighteen control patients (female [n = 7, 39%]; median age 61 years, range 41–83) were included using the same DECT protocol. All control patients were diagnosed with non-metastatic malignant melanoma; other hematologic neoplasms were not present. The analysis adhered to the principles of the Declaration of Helsinki and was approved by the relevant institutional review board (Mannheim Medical School, University of Heidelberg). All patients gave their informed consent in writing.
Diagnosis and subclassification
Diagnosis and subclassification were made according to the revised World Health Organization (WHO) 2017 classification: ISM in 6/18 (33%) and SSM/AdvSM in 12/18 (67%) patients ( Tables 1, 2)1,2,24. The diagnosis of SSM was established by the presence of at least two of the three B findings (MC infiltration >30% and serum tryptase level >200 ng/mL; signs of dysplasia or myeloproliferation in non-lineage compartments). CD of BM, but no AHN; hepatomegaly without impaired liver function and/or splenomegaly and/or lymphadenopathy). The diagnosis of MSA was based on the presence of one or more C findings (cytopenia with neutropenia 9/L, anemia 9/L, palpable hepatomegaly with impaired liver function, palpable splenomegaly with signs of hypersplenism, malabsorption with weight loss due to gastrointestinal infiltrates of CD or skeletal involvement with significant osteolytic lesions and/or pathologic fractures). SM-AHN met criteria for both SM and AHN (eg, chronic myelomonocytic leukemia, unclassified myelodysplastic/myeloproliferative neoplasm [MDS/MPNu] or chronic eosinophilic leukemia). MCL was diagnosed based on the presence of at least ≥ 20% MC in a BM smear.
Treatment
Patients with ISM received conventional symptom-focused therapy including H1 and H2 antagonists, cromolyn acid, proton pump inhibitors, and corticosteroids. One patient with SSM was treated with hydroxyurea. All patients with AdvSM were treated with midostaurin, a multikinase inhibitor; 3 patients also received the purine analogue cladribine as second-line treatment. The use of bisphosphonates has not been documented in any patient at the time of DECT.
DECT scanning protocol, image reconstruction and post-processing
All examinations were performed on a dual-source CT system in dual-energy mode (SOMATOM Force; Siemens Healthineers, Forchheim, Germany). The median time from diagnosis to DECT was 1.0 years (range 0–11.0). For the assessment of osteosclerosis, weighted mean coronal and sagittal multiplanar reformations were calculated. For DECT post-processing, axial slices with a thickness of 1.0 mm were reconstructed. Post-processing was performed on dedicated dual-energy software (Syngo.via; version VB30A; Siemens Healthineers) with a three-material decomposition algorithm for bone mineral, yellow marrow and red marrow25. For further evaluation, DECT images were viewed as weighted mean CT merged with color-coded VNCa overlay using BM setting (Siemens Healthineers).
Evaluation of CT images
Qualitative image analysis of osteosclerosis
CT images were reviewed by consensus by two attending radiologists each with 10 years of body imaging experience on a commercially available MacPro workstation (Apple, Cupertino, CA) running OsiriX DICOM Viewer 64-bit Version 5.5.2 ( OsiriX Foundation, Geneva, Switzerland) without knowledge of clinical results or classification. Based on our previous experience, three distinct patterns have been defined: normal bone structure, diffuse osteosclerosis, and multiple focal sclerotic bone lesions.
Quantitative image analysis
All images were analyzed separately in a randomized order by two readers (JR and PR) each with 10 years of experience in oncology imaging. Readers were blinded to clinical data and VNCa-AV measurements were performed on a consensus basis. In MS patients and patients in the control group, five measurements of the circular region of interest (ROI) of at least 100 mm2 were obtained between Th11–12 and L1–3. ROI borders were kept 2 mm from adjacent cortical bone to include only BM in the assessment. Non-myeloma lesions, such as Schmorl’s nodes and hemangiomas, were not included in the ROIs. For further analysis, the average values of the five ROIs were used.
Statistics
All statistical analyzes took into account clinical and laboratory parameters obtained at the time of imaging. The Mann-Whitney U test was used to compare the continuous variables and the medians of the distributions. Pearson’s correlation coefficient was used to compare VNCa-AV with various disease-specific parameters (eg, BM MC infiltration, serum tryptase level). P values
