title: Correlation Between SUVmax and CT Radiomic Analysis Using Lymph Node Density in PET/CT-Based Lymph Node Staging.
abstract: In patients with lung cancer (LC), malignant melanoma (MM), gastroenteropancreatic neuroendocrine tumors (GEP NETs), and prostate cancer (PCA), lymph node (LN) staging is often performed by18F-FDG PET/CT (LC and MM),68Ga-DOTATOC PET/CT (GEP NET), and68Ga-labeled prostate-specific membrane antigen PET/CT (PCA) but is sometimes not accurate because of indeterminate PET findings. To better evaluate malignant LN infiltration, additional surrogate parameters, especially in cases with indeterminate PET findings, would be helpful. The purpose of this study was to evaluate whether SUVmaxin the PET examination might correlate with semiautomated density measurements of LNs in the CT component of the PET/CT examination.
  
  
  METHODS
  After approval by the institutional review board, 1,022 LNs in the PET/CT examinations of 148 patients were retrospectively analyzed (LC: 327 LNs of 40 patients; MM: 224 LNs of 33 patients; GEP NET: 217 LNs of 35 patients; and PCA: 254 LNs of 40 patients). PET/CT was performed before surgery, biopsy, chemotherapy, or internal or external radiation therapy, according to the clinical schedule; patients with prior chemotherapy or radiation therapy were excluded. SUVmaxanalyses were based on uptake 60 min after tracer injection, and volumetric CT histogram analyses were based on the unenhanced CT images of the PET/CT scan.
  
  
  RESULTS
  PET findings were considered positive or negative on the basis of SUVmaxin the LN compared with that in the blood pool; histologic confirmation was not available. Of the 1,022 LNs, 331 were PET-positive (3 times the SUVmaxof the blood pool), 86 were PET-indeterminate (1-3 times the SUVmaxof the blood pool), and 605 were PET-negative (less than the SUVmaxof the blood pool). PET-positive LNs had significantly higher CT densities than PET-negative LNs, irrespective of the type of cancer.
  
  
  CONCLUSIONS
  CT density measurements of LNs in patients with LC, MM, GEP NET, and PCA correlated with18F-FDG uptake,68Ga-DOTATOC uptake, and68Ga-PSMA uptake, respectively, and might therefore serve as an additional surrogate parameter for differentiating between malignant and benign LNs. The use of a 7.5-Hounsfield unit CT density threshold to differentiate between malignant and benign LN infiltration and 20 Hounsfield units to exclude benign LN processes might be possible in clinical routine and would be especially helpful for PET-indeterminate LNs.
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.|Clinical Cooperation Unit, Department of Nuclear Medicine, DKFZ, Heidelberg, Germany.
authors.forename: Frederik L
authors.initials: FL
authors.lastname: Giesel
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Schneider
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: Kratochwil
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rath
authors.affiliation: Fraunhofer Institute for Medical Image Computing, Bremen, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Moltz
authors.affiliation: Department of Biostatistics, German Cancer Research Center, Heidelberg, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Holland-Letz
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany.|Translational Lung Research Center Heidelberg, Heidelberg, Germany; and.
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.affiliation: Department of Radiology, New York-Presbyterian/Columbia University Medical Centre, New York, New York.
authors.forename: Lawrence H
authors.initials: LH
authors.lastname: Schwartz
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.|Clinical Cooperation Unit, Department of Nuclear Medicine, DKFZ, Heidelberg, Germany.|Translational Lung Research Center Heidelberg, Heidelberg, Germany; and.
authors.forename: Uwe
authors.initials: U
authors.lastname: Haberkorn
authors.affiliation: Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany paul.flechsig@med.uni-heidelberg.de.|Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany.|Translational Lung Research Center Heidelberg, Heidelberg, Germany; and.
authors.forename: Paul
authors.initials: P
authors.lastname: Flechsig
mesh_terms: D000465:Algorithms; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008198:Lymph Nodes; D008207:Lymphatic Metastasis / Q000000981:diagnostic imaging* / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D010363:Pattern Recognition, Automated / Q000379:methods; D000072078:Positron Emission Tomography Computed Tomography; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D000071036:Sentinel Lymph Node / Q000000981:diagnostic imaging* / Q000473:pathology*; D013223:Statistics as Topic; D014057:Tomography, X-Ray Computed
keywords: DOTATOC PET/CT; FDG PET/CT; N staging; PSMA PET/CT; radiomics