title: (18)F-FDG dynamic PET/CT in patients with multiple myeloma: patterns of tracer uptake and correlation with bone marrow plasma cell infiltration rate.
abstract: OBJECTIVE
  The value of F-FDG PET in the diagnostic approach of multiple myeloma (MM) remains incompletely elicited. Little is known about the kinetics of F-FDG in the bone marrow and extramedullary sites in MM. This study aimed to evaluate quantitative data on kinetics and distribution patterns of F-FDG in MM patients with regard to pelvic bone marrow plasma cell infiltration.
  
  
  METHODS
  The study included 40 patients with primary MM. Dynamic PET/CT scanning of the lower lumbar spine and pelvis was performed after the administration of F-FDG. Whole-body PET/CT studies were performed. Sites of focal increased tracer uptake were considered as highly suggestive of myelomatous involvement after taking into account the patient history and CT findings. Bone marrow of the os ilium without pathologic tracer accumulation served as reference. The evaluation of dynamic PET/CT studies was based in addition to the conventional visual (qualitative) assessment, on semiquantitative (SUV) calculations, as well as on absolute quantitative estimations after application of a 2-tissue compartment model and a noncompartmental approach. F-FDG quantitative information and corresponding distribution patterns were correlated with pelvic bone marrow plasma cell infiltration.
  
  
  RESULTS
  Fifty-two myelomatous lesions were detected in the pelvis. All parameters in suspected MM lesions ranged in significantly higher levels than in reference tissue (P < 0.01). Correlative analyses revealed that bone marrow plasma cell infiltration rate correlated significantly with SUVaverage, SUVmax, and the parameters K1, influx, and fractal dimension of F-FDG in reference bone marrow (P < 0.01). In addition, whole-body static PET/CT imaging demonstrated 4 patterns of tracer uptake; these are as follows: negative, focal, diffuse, and mixed (focal/diffuse) tracer uptake. Patients with a mixed pattern of radiotracer uptake had the highest mean plasma cell infiltration rate in their bone marrow, whereas those with negative PET/CT scans demonstrated the lowest bone marrow plasma cell infiltration. In total, 265 focal myeloma-indicative F-FDG-avid lesions were detected, 129 of which correlated with low-dose CT osteolytic findings. No significant correlation between the number of focal lesions detected in PET/CT and bone marrow infiltration was detected.
  
  
  CONCLUSIONS
  The F-FDG kinetic parameters K1, influx, and fractal dimension as well as SUVaverage from reference tissue correlated significantly with bone marrow malignant plasma cell infiltration rate. Patients with negative PET/CT demonstrated the lowest bone marrow infiltration by malignant plasma cells, whereas those with a mixed pattern of tracer uptake had the highest infiltration.
authors.affiliation: From the *Clinical Cooperation Unit Nuclear Medicine, German Cancer Research Center; †Medical Clinic V, University Hospital Heidelberg; ‡National Center for Tumor Diseases Heidelberg; §Department of Radiology, German Cancer Research Center; and ║Division of Nuclear Medicine, University of Heidelberg, Heidelberg, Germany.
authors.forename: Christos
authors.initials: C
authors.lastname: Sachpekidis
authors.forename: Elias K
authors.initials: EK
authors.lastname: Mai
authors.forename: Hartmut
authors.initials: H
authors.lastname: Goldschmidt
authors.forename: Jens
authors.initials: J
authors.lastname: Hillengass
authors.forename: Dirk
authors.initials: D
authors.lastname: Hose
authors.forename: Leyun
authors.initials: L
authors.lastname: Pan
authors.forename: Uwe
authors.initials: U
authors.lastname: Haberkorn
authors.forename: Antonia
authors.initials: A
authors.lastname: Dimitrakopoulou-Strauss
mesh_terms: D000368:Aged; D001853:Bone Marrow / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009101:Multiple Myeloma / Q000000981:diagnostic imaging* / Q000473:pathology; D009361:Neoplasm Invasiveness / Q000000981:diagnostic imaging; D010950:Plasma Cells / Q000473:pathology*; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18