Y. Maruyama

Atypical adenomatous hyperplasia of the lung: correlation between high-resolution CT findings and histopathologic features.

Abstract We describe herein the CT features of atypical adenomatous hyperplasia (AAH) of the lung and its histopathological characteristics. Among 17,919 individuals screened for lung cancer by CT scanning, ten AAH nodules were detected in nine asymptomatic subjects. On high-resolution CT, the lesions measured from 6 × 6 mm to 15 × 17 mm and their CT number ranged from –500 to –760 HU. The AAHs appeared as round nodules with smooth and distinct borders and showed a ground-glass opacity. Plain chest radiographs failed to identify all lesions. Histopathologically, AAH lesions showed atypical epithelial cell proliferation along slightly thickened alveolar septa. Whereas it is often easy to differentiate these nodules from inflammatory and benign lung lesions, histopathological examination remains at present the only method to differentiate AAH from lung cancers.

Correlation between high-resolution computed tomographic, magnetic resonance and pathological findings in cases with non-cancerous but suspicious lung nodules

Abstract. Computed tomography scans, including thin-section high-resolution computed tomography (HRCT), occasionally fail to differentiate between small non-cancerous nodules from lung cancers. We describe nine such lesions ( < 20 mm in diameter) initially identified through our screening program for lung cancer using CT scanning. Pathological diagnoses included nodular fibrosis (n = 4), granuloma (n = 1), cryptococcoma (n = 1), localised organising pneumonia (n = 1), inflammatory pseudo-tumour (n = 1) and sclerosing haemangioma (n = 1). High-resolution CT findings, together with MRI findings with contrast-enhanced dynamic studies, were retrospectively evaluated. Additional cases should be identified and radiologically characterised in order to reduce the number of non-cancerous tumours that are treated by unnecessary surgery.

OPTIMAL TUBE CURRENT FOR LUNG CANCER SCREENING WITH LOW‐DOSE SPIRAL CT

PURPOSE To determine the optimal tube current for spiral CT for lung cancer screening. MATERIAL AND METHODS Low-dose spiral CT images from 20 subjects were obtained with 50 mA, 25 mA, 10 mA and 5 mA tube currents. The accuracy in detecting 21 nodules measuring 3 to 14 mm in diameter was tested using receiver operating characteristics (ROC) to determine the diagnostic accuracy and statistical significance. RESULTS Compared with 50 mA, 25 mA showed no statistical difference. A significant difference was seen between 50 mA and 5 mA images and between 25 mA and 10 mA images, in the detection of lung parenchymal nodular lesions. CONCLUSION Approximately 25 mA is the optimal tube current for the detection of pulmonary nodules as it allows a reduction of the radiation dose without sacrificing diagnostic accuracy.

Magnetic resonance imaging of neurogenic tumors of the thoracic inlet : Determination of the parent nerve

To investigate the value of magnetic resonance imaging (MRI) in determining the parent nerves of neurogenic tumors in the thoracic inlet, analysis of MR images was performed in nine patients with surgically resected neurogenic tumors in the thoracic inlet (two neurofibromas and one schwannoma of the vagus nerve, three schwannomas of the brachial plexus, and two schwannomas and one ganglioneuroma of the sympathetic nerves). These MR images were compared with surgical and pathologic findings. The multidirectional capability and excellent tissue contrast of MRI facilitated recognition of the location, shape, and extent of the tumors. MRI, which permitted an easy understanding of the spatial relation between the tumors and the subclavian vessels, scalenus muscles, and brachial plexus, was useful in determining the nerves of origin. Two neurofibromas, four of six schwannomas, and one ganglioneuroma were recognized to extend along the axes of the parent nerves on MR images. MRI is useful in determining the parent nerve of neurogenic tumors in the thoracic inlet and is helpful in planning surgical treatment of these tumors.

Detection of small peripheral lung cancer by digital chest radiography. Performance of unprocessed versus unsharp mask-processed images.

Purpose: To clarify whether processed digital chest radiography can improve the detection rate for small peripheral lung cancer. Material and Methods: Five radiologists independently interpreted 54 digitized chest radiographs of 18 patients with small peripheral lung cancers measuring less than 20 mm, which were displayed following 3 types of digital processing: 1) an original version; 2) unsharp mask processing with a type 1 filter (very low-frequency-enhancing, mid-frequency-suppressing, and high-frequency-enhancing filter); and 3) unsharp mask processing with a type 2 filter (very low— and high-frequency-enhancing filter). A total of 1,620 pooled observations were evaluated by receiver operating characteristic (ROC) analysis. Results: the mean area under the ROC curves was 0.68 for the type 1 filter, 0.68 for the type 2 filter, and 0.65 for the unprocessed (original) image. There were no statistically significant differences among these 3 kinds of image processing (p>0.05). In all types of images, the small lung cancer with an alveolar lining tumor growth was less visible than a solid tumor growth (p<0.01); the sensitivity increased with tumor size when the 3 groups of cancers, those measuring less than 10 mm, 11–15 mm, and 16–20 mm, were compared (p<0.01). Conclusion: Unsharp mask-image processing of digital chest radiography will not improve the detection rate of small peripheral lung cancer, probably due to a substantial drawback: the limited conspicuity of cancer lesions in the surrounding lung and superposition of structures.

Primary Malignant Lymphoma in the Posterior Mediastinum

We present a case of primary malignant lymphoma arising from the posterior mediastinum. A 63-year-old woman was admitted to our hospital for further examination of her chest radiographic findings. She was asymptomatic. Chest computed tomography (CT) and magnetic resonance imaging (MRI) showed a posterior mediastinal mass in the right thoracic paravertebral region. A percutaneous needle biopsy was performed under CT. The histological findings with immunochemical staining revealed a B cell type of diffuse malignant lymphoma. 67Ga scintigraphy revealed accumulation in this area, suggesting the posterior mediastinum as the origin of the disease. Reports of primary malignant lymphoma in the posterior mediastinum are extremely rare. The radiographic characteristics are discussed.