Junko Sadohara

Dynamic MRI of Solitary Pulmonary Nodules: Comparison of Enhancement Patterns of Malignant and Benign Small Peripheral Lung Lesions

OBJECTIVE The purpose of this study was to compare the dynamic contrast-enhanced MRI enhancement characteristics of malignant and benign solitary pulmonary nodules. MATERIALS AND METHODS The characteristics of 202 solitary pulmonary nodules (diameter, 1-3 cm; 144 cases of primary lung cancer, 31 cases of focal organizing pneumonia, 15 tuberculomas, 12 hamartomas) were reviewed retrospectively. In all cases dynamic MR images were obtained before and 1, 2, 3, 4, 5, 6, and 8 minutes after bolus injection of gadopentetate dimeglumine. Maximum enhancement ratio, time at maximum enhancement ratio, slope of time-enhancement ratio curves, and washout ratio were assessed. Statistical analyses were performed with the Kruskal-Wallis test with Bonferroni correction, chi-square test, and receiver operating characteristic curves. RESULTS For 122 (85%) of 144 primary lung cancers, time at maximum enhancement ratio was 4 minutes or less. For all tuberculomas and hamartomas, time at maximum enhancement ratio was greater than 4 minutes or gradual enhancement occurred without a peak time (p < 0.0001). Lung cancers had different maximum enhancement ratios and slopes than benign lesions (all p < 0.005). With 110% or lower maximum enhancement ratio as a cutoff value, the positive predictive value for malignancy was 92%; sensitivity, 63%; and specificity, 74%. With 13.5%/min or greater slope as a cutoff value, sensitivity, specificity, positive predictive value, and negative predictive value for malignancy were 94%, 96%, 99%, and 74%, respectively. CONCLUSION Dynamic contrast-enhanced MRI is helpful in differentiating benign from malignant solitary pulmonary nodules. Absence of significant enhancement is a strong predictor that a lesion is benign.

MR imaging of thymic epithelial tumors: correlation with World Health Organization classification.

PurposeThe aim of this study was to determine magnetic resonance imaging (MRI) features of various subtypes of thymic epithelial tumors based on the World Health Organization classification.Materials and methodsThe study included 64 patients with histologically proven thymic epithelial tumors. Two observers evaluated the MRI findings in terms of tumor size, contour, lobulation, shape, homogeneity, the presence of intratumor high- and low-signal foci, enhancement degree and pattern, the presence of capsule and septum, and associated mediastinal lymphadenopathy and pleural effusion.ResultsType A tumors were more likely to have a smooth contour, round shape, distinct capsule, and smaller size compared to any other type of thymic epithelial tumor. Thymic carcinomas demonstrated a higher prevalence of low-signal foci within the mass on T2-weighted images and mediastinal lymphadenopathy than any other types. The frequency of heterogeneous intensity on T2-weighted images increased from type A tumors to thymic carcinomas.ConclusionThe presence of a smooth contour, round shape, and capsule is highly suggestive of a type A tumor. Foci of low signal intensity in the mass on T2-weighted images and mediastinal lymphadenopathy are highly suggestive of thymic carcinomas.

Alveolar adenoma of the lung: computed tomography and magnetic resonance imaging findings.

Alveolar adenoma of the lung is a rare benign neoplasm with distinctive gross and microscopic findings. Radiographically, alveolar adenoma usually presents as a well-circumscribed, peripheral, solitary nodule. The authors describe the contrast-enhanced computed tomography and magnetic resonance imaging features of alveolar adenoma of lung. Magnetic resonance imaging demonstrated the presence of a cystic space with central fluid and thin-rim enhancement. These findings are suggestive of a benign nodule, and alveolar adenoma of lung should be added to the differential diagnosis of nodules that demonstrate this pattern of enhancement and are probably benign.

Bronchioloalveolar carcinoma with fluctuating extent of consolidation on chest radiography.

We report a case of bronchioloalveolar carcinoma that required approximately 1 year to diagnose due to alternating periods of exacerbation and improvement of abnormal opacity on chest radiography. It is important to consider the diagnosis of bronchioloalveolar carcinoma when consolidative opacities simulating pneumonia show an alternating pattern of worsening and improvement.

Interstitial Pneumonia associated with ulcerative colitis: high-resolution computed tomography and pathologic findings.

Pulmonary parenchymal manifestations associated with ulcerative colitis (UC) include various conditions such as opportunistic infections, interstitial pneumonia, organizing pneumonia, and adverse drug reactions. We present a case of interstitial pneumonia associated with UC in a 61-year-old nonsmoking woman. High-resolution computed tomography demonstrated multifocal ill-defined areas of consolidation and ground-glass attenuation with or without traction bronchiectasis, predominantly in peripheral lung parenchyma. Lung biopsy showed that the closest pathologic pattern in the areas of abnormality was cellular and fibrotic nonspecific interstitial pneumonia. We also discuss the evaluation and treatment of pulmonary disease possibly related to UC in the clinical course of this patient.