Objectives This study describes the magnetic resonance findings of benign a
nd malignant pleural diseases in asbestos-exposed subjects.
Methods Thirty patients with a history of asbestos exposure and pleural les
ions in chest X-rays and computed tomography scans were examined with a 0.5
- and a 1.5-T magnetic resonance unit. The examination protocol included ca
rdiac-gated proton density and T2-weighted images, unenhanced and enhanced
(Gd-DTPA; 0.1 mmol/kg) T1-weighted images in the axial plane and sometimes
in another orthogonal plane (sagittal or coronal or both). All the magnetic
resonance images were reviewed by 3 experienced observers, who visually ev
aluated morphologic features, signal intensity, and contrast enhancement of
pleural lesions. The diagnosis was established by means of percutaneous bi
opsy, thoracotomy, and combined clinical and radiological follow-up for at
least 3 years.
Results Eighteen patients affected with multiple pleural plaques showed low
signal intensity on both unenhanced and enhanced T1 weighted and proton de
nsity and T2-weighted images. In 2 of these patients an acute pleural effus
ion was observed. All the malignant lesions (11 mesotheliomas) and a solita
ry benign pleural plaque revealed high signal intensity on the proton densi
ty and T2-weighted images and inhomogeneous contrast enhancement in the pos
tcontrast T1-weighted images. The sensitivity, specificity, and diagnostic
accuracy of the magnetic resonance imaging in classifying a lesion as sugge
stive of malignancy were 100%, 95% and 97%, respectively.
Conclusions The results point out 2 magnetic resonance signal intensity pat
terns for asbestos-related pleural lesions: (i) low-signal intensity on une
nhanced and enhanced T1-weighted and proton density and T2-weighted images
for benign plaques and (ii) nonhomogeneous hyperintensity in T2-weighted an
d enhanced T1-weighted images for malignant mesotheliomas.