Diagnostic efficacy and characteristic feature of mri in pulmonary hamartoma: Comparison with CT, specimen MRI, and pathology

OBJECTIVES:: To determine the diagnostic efficacy of magnetic resonance imaging (MRI) in pulmonary hamartoma and observe the significant MRI features, other than fat or characteristic calcification revealed by computed tomography (CT). METHODS:: Six hamartomas were included and surgically resected, and we prospectively studied MRI in cases showing suggestive findings of hamartoma or indeterminate nodule on CT. We analyzed the tumor on CT and MRI (available enhancement study in 4) focusing on cleftlike structure in comparison with specimen MRI (n ≤ 3) and histopathologic findings: presence, shape, and distribution of the cleftlike structure and signal intensity and enhancement of the cleftlike structure and main portion. RESULTS:: Computed tomography revealed suggestive findings of pulmonary hamartoma (fat or popcorn calcification) in only 3. All MRI revealed cleftlike structures particularly evident on T2-weighted images with same detectability as its specimen MRI: peripheral linear or curvilinear inclusions with sometimes intratumoral cleftlike space (n ≤ 3), variable signal intensity, and frequent enhancement (3 in 4) pathologically correlated with the variable mesenchymal tissue components and amount arrayed along respiratory epithelial cells lining the cleft and richer vascularity than main portion of pulmonary hamartoma. CONCLUSIONS:: Magnetic resonance imaging study is a useful diagnostic tool, when a discrete pulmonary nodule demonstrates neither fat nor calcification on CT, for detecting the quite typical cleftlike structure in a pulmonary hamartoma and could provide diagnostic confidence.