title: Dual-energy CT: virtual calcium subtraction for assessment of bone marrow involvement of the spine in multiple myeloma.
abstract: OBJECTIVE. Dual-energy CT (DECT) enables subtraction of calcium, facilitating the visualization of bone marrow (BM) in the axial skeleton. The purpose of this study was to assess whether DECT BM images have the potential to improve the detection of multifocal and diffuse BM infiltration in multiple myeloma (MM) in comparison with regular CT with MRI as the reference standard. SUBJECTS AND METHODS. This study included 32 consecutive patients who had known MM or presented with monoclonal gammopathy of unknown significance and underwent DECT and MRI of the axial skeleton. The degrees (none, n = 14; moderate, n = 10; and high, n = 8) and patterns (diffuse, n = 10 or multifocal, n = 8) of infiltration were assessed on MR images. Attenuation in BM and CT images in known uninvolved and involved areas was measured. Cutoff values of attenuation in BM images for infiltration in lytic and nonlytic lesions were established by ROC analysis. At least 120 days later, sensitivity and specificity for reading CT images alone and when using additional BM images were evaluated. RESULTS. ROC analysis revealed larger AUC in BM images than in CT images; cutoff values for marrow invasion in BM images were 4 and -3 HU in lytic and nonlytic lesions, respectively. In the blinded reading session, BM images improved the sensitivity for the detection of diffuse infiltration from 0 to as much as 75% for cases with high-grade infiltration. In multifocal patterns, BM images did not significantly change the detection rate. CONCLUSION. BM images have the potential to improve the sensitivity for detection of diffuse BM involvement in comparison with regular CT.
authors.affiliation: 1 Department of Diagnostic and Interventional Radiology, Eberhard-Karls-University, Hoppe-Seyler-Str 3, 72076 Tübingen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Thomas
authors.forename: Christoph
authors.initials: C
authors.lastname: Schabel
authors.forename: Bernhard
authors.initials: B
authors.lastname: Krauss
authors.forename: Katja
authors.initials: K
authors.lastname: Weisel
authors.forename: Malte
authors.initials: M
authors.lastname: Bongers
authors.forename: Claus D
authors.initials: CD
authors.lastname: Claussen
authors.forename: Marius
authors.initials: M
authors.lastname: Horger
mesh_terms: D000368:Aged; D002118:Calcium; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000473:pathology*; D011446:Prospective Studies; D013120:Spinal Cord Neoplasms / Q000473:pathology*; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D002118:Calcium
keywords: bone marrow; calcium; dual-energy CT; multiple myeloma; noncalcium; spine