title: Detection and size of pulmonary lesions: how accurate is MRI? A prospective comparison of CT and MRI.
abstract: BACKGROUND
  Although CT is the modality of choice for morphological lung imaging, an increasing proportion of chest imaging is performed by MRI due to the utilization of whole-body MRI. Therefore, the diagnostic performance of MRI in reliably detecting pulmonary lesions should be established.
  
  
  OBJECTIVE
  To investigate the detection rate of pulmonary lesions by MRI that can be expected in a clinical setting and to assess the accuracy of lesion measurement by MRI compared to CT.
  
  
  METHODS
  Twenty-eight patients (median age 66 years) with indication for CT imaging due to suspected thoracic malignancy were prospectively included. Chest MRI performed on the same day as CT, comprised unenhanced TrueFisp, ecg-gated T2-weighted HASTE, T1-weighted VIBE, and contrast-enhanced T1-weighted, fat-saturated VIBE sequences. MR sequences were evaluated for lesion detection by two readers independently and measurement of lesion size was performed. MR findings were correlated with CT.
  
  
  RESULTS
  One hundred and eight pulmonary lesions (20 thoracic malignancies, 88 lung nodules) were detected by CT in 26 patients. Lesions were ruled out in two patients. All thoracic malignancies were identified by MRI with strong correlation (r = 0.97-0.99; P < 0.01) in lesion size measurement compared to CT. Unenhanced, T1-weighted VIBE correctly classified 94% of thoracic malignancies into T-stages. Contrast-enhanced, T1-weighted VIBE performed best in identifying 36% of lung nodules, 40% were detected combining unenhanced and contrast-enhanced T1-weighted VIBE. Detection rate increased to 65% for the combined sequences regarding lesions ≥5 mm. Lesion size measurement by all MR sequences strongly correlated with CT (r = 0.96-0.97; P = 0.01).
  
  
  CONCLUSIONS
  MRI is as accurate as CT in detection and size measurement of primary thoracic malignancies >1 cm in diameter. If a lung lesion is detected by MRI, it is a reliable finding and its measurement is accurate. CT remains superior in detecting small lung nodules (<6 mm). Detection rate of MRI for small lesions is improved using a multi-sequence protocol including contrast administration.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg, Germany. tobias.heye@med.uni-heidelberg.de
authors.forename: Tobias
authors.initials: T
authors.lastname: Heye
authors.forename: Sebastian
authors.initials: S
authors.lastname: Ley
authors.forename: Claus Peter
authors.initials: CP
authors.lastname: Heussel
authors.forename: Hendrik
authors.initials: H
authors.lastname: Dienemann
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Kauczor
authors.forename: Waldemar
authors.initials: W
authors.lastname: Hosch
authors.forename: Martin
authors.initials: M
authors.lastname: Libicher
mesh_terms: D000368:Aged; D003287:Contrast Media; D004562:Electrocardiography; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015588:Observer Variation; D011446:Prospective Studies; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA