title: Pulmonary MRI at 3T: Non-enhanced pulmonary magnetic resonance Imaging Characterization Quotients for differentiation of infectious and malignant lesions.
abstract: OBJECTIVE
  To investigate 3T pulmonary magnetic resonance imaging (MRI) for characterization of solid pulmonary lesions in immunocompromised patients and to differentiate infectious from malignant lesions.
  
  
  METHODS
  Thirty-eight pulmonary lesions in 29 patients were evaluated. Seventeen patients were immunocompromised (11 infections and 6 lymphomas) and 12 served as controls (4 bacterial pneumonias, 8 solid tumors). Ten of the 15 infections were acute. Signal intensities (SI) were measured in the lesion, chest wall muscle, and subcutaneous fat. Scaled SIs as Non-enhanced Imaging Characterization Quotients ((SILesion-SIMuscle)/(SIFat-SIMuscle)*100) were calculated from the T2-weighted images using the mean SI (T2-NICQmean) or the 90th percentile of SI (T2-NICQ90th) of the lesion. Simple quotients were calculated by dividing the SI of the lesion by the SI of chest wall muscle (e.g. T1-Qmean: SILesion/SIMuscle).
  
  
  RESULTS
  Infectious pulmonary lesions showed a higher T2-NICQmean(40.1 [14.6-56.0] vs. 20.9 [2.4-30.1], p<0.05) and T2-NICQ90th(74.3 [43.8-91.6] vs. 38.5 [15.8-48.1], p<0.01) than malignant lesions. T1-Qmeanwas higher in malignant lesions (0.85 [0.68-0.94] vs. 0.93 [0.87-1.09], p<0.05). Considering infections only, T2-NICQ90thwas lower when anti-infectious treatment was administered >24h prior to MRI (81.8 [71.8-97.6] vs. 41.4 [26.6-51.1], p<0.01). Using Youden's index (YI), the optimal cutoff to differentiate infectious from malignant lesions was 43.1 for T2-NICQmean(YI=0.42, 0.47 sensitivity, 0.95 specificity) and 55.5 for T2-NICQ90th(YI=0.61, 0.71 sensitivity, 0.91 specificity). Combining T2-NICQ90thand T1-Qmeanincreased diagnostic performance (YI=0.72, 0.77 sensitivity, 0.95 specificity).
  
  
  CONCLUSIONS
  Considering each quotient alone, T2-NICQ90thshowed the best diagnostic performance and could allow differentiation of acute infectious from malignant pulmonary lesions with high specificity. Combining T2-NICQ90thwith T1-Qmeanincreased overall performance, especially regarding sensitivity.
authors.affiliation: Klinik und Hochschulambulanz für Radiologie, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany. Electronic address: sebastian.nagel@charite.de.
authors.forename: Sebastian Niko
authors.initials: SN
authors.lastname: Nagel
authors.affiliation: Klinik und Hochschulambulanz für Radiologie, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany; Institut für Röntgendiagnostik, HELIOS Klinikum Berlin-Buch, Schwanebecker Chaussee 50, 13125 Berlin, Germany. Electronic address: damon.kim@charite.de.
authors.forename: Damon
authors.initials: D
authors.lastname: Kim
authors.affiliation: Klinik und Hochschulambulanz für Radiologie, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany. Electronic address: tobias.penzkofer@charite.de.
authors.forename: Tobias
authors.initials: T
authors.lastname: Penzkofer
authors.affiliation: Klinik und Hochschulambulanz für Radiologie, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany. Electronic address: ingo.steffen@charite.de.
authors.forename: Ingo G
authors.initials: IG
authors.lastname: Steffen
authors.affiliation: Klinik und Hochschulambulanz für Radiologie, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany. Electronic address: sebastian.wyschkon@charite.de.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Wyschkon
authors.affiliation: Klinik und Hochschulambulanz für Radiologie, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany. Electronic address: bernd.hamm@charite.de.
authors.forename: Bernd
authors.initials: B
authors.lastname: Hamm
authors.affiliation: Medizinische Klinik mit Schwerpunkt Hämatologie und Onkologie, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany. Electronic address: stefan.schwartz@charite.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schwartz
authors.affiliation: Klinik und Hochschulambulanz für Radiologie, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany. Electronic address: thomas.elgeti@charite.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Elgeti
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging* / Q000473:pathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011014:Pneumonia / Q000000981:diagnostic imaging* / Q000473:pathology; D011446:Prospective Studies; D012680:Sensitivity and Specificity
keywords: Characterization; Chest; Infectious vs. malignant; Lesions; MRI