Detection of small pulmonary nodules in high-field MR at 3 T: evaluation of different pulse sequences using porcine lung explants.
To evaluate two MR imaging sequences for the detection of artificial pulmonary nodules inside porcine lung explants. 67 agarose nodules ranging 3-20 mm were injected into ten porcine lungs within a dedicated chest phantom. The signal on T1-weighted images and radiopacity were adjusted by adding 0.125 mmol/l Gd-DTPA and 1.5 g/l of iodine. A T1-weighted three-dimensional gradient-echo (T1-3D-GRE; TR/TE:3.3/1.1 ms, slice:8 mm, flip-angle:10 degrees ) and a T2-weighted half-Fourier fast-spin echo sequence (T2-HF-FSE; TR/TE:2000/66 ms, slice:7 mm, flip-angle:90 degrees ) were applied in axial orientation using a 3-T system (Intera, Philips Medical Systems, Best, The Netherlands), followed by CT (16x0.5 mm) as reference. Nodule sizes and locations were assessed by three blinded observers. In nodules of >10 mm, sensitivity was 100% using 3D-GRE-MRI and 94% using the HF-FSE sequence. For nodules 6-10 mm, the sensitivity of MRI was lower than with CT (3D-GRE:92%; T2-HF-FSE:83%). In lesions smaller than 5 mm, the sensitivity declined to 80% (3D-GRE) and 53% (HF-FSE). Small lesion diameters were overestimated with both sequences, particularly with HF-FSE. This study confirms the feasibility of 3 T-MRI for lung nodule detection. In lesions greater than 5 mm, the sensitivity of the 3D-GRE sequence approximated CT (>90%), while sensitivity and PPV with the HF-FSE sequence were slightly inferior.
Regier
M
M
Center for Diagnostic Imaging and Image Guided Therapy, Department of Diagnostic and Interventional Radiology, University Hospital of Hamburg, Eppendorf, Martinistrasse 52, 20246, Hamburg, Germany. mregier@uke.uni-hamburg.de
Kandel
S
S
Kaul
M G
MG
Hoffmann
B
B
Ittrich
H
H
Bansmann
P M
PM
Kemper
J
J
Nolte-Ernsting
C
C
Heller
M
M
Adam
G
G
Biederer
J
J
D000818:Animals; D016001:Confidence Intervals; D003287:Contrast Media; D019786:Gadolinium DTPA; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D008171:Lung Diseases / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D013552:Swine; D014057:Tomography, X-Ray Computed
D003287:Contrast Media; D019786:Gadolinium DTPA