An integrated approach to evaluation of the solitary pulmonary nodule

In this article, we describe an integrated approach for detection and evaluation of solitary pulmonary nodules. Initial evaluation of the solitary pulmonary nodule includes tomography, fluoroscopy, and comparison with previously obtained roentgenograms. Subsequently, thin-section computed tomography and phantom densitometry can be used for analysis, if indicated. The rationale for the use of computed tomography in the radiologic staging of bronchogenic carcinoma is to expedite and assist in the identification of the subset of patients with resectable tumors. For nonsurgical tissue diagnosis, fiberoptic bronchoscopy is generally the initial procedure for lesions 2.0 cm or larger in diameter, and transthoracic needle biopsy is used for those smaller than 2.0 cm.

High-resolution computed tomography of the lung

High-resolution computed tomography (HRCT) and thin-section CT are techniques that are particularly suited for evaluation of the pulmonary parenchyma. These techniques have been found useful in the assessment of bronchiectasis and solitary pulmonary nodules. HRCT offers promise in evaluation of diffuse and focal pulmonary parenchymal disease. The principles and applications of HRCT of the lung are reviewed.

Magnetic resonance imaging of the thorax

The role of magnetic resonance imaging (MRI) in the evaluation of thoracic disease is emerging amidst much debate and study. Recent technical advances have led to new applications of this modality, and a reappraisal of previous conclusions seems warranted. This article reviews our 5 1/2 years' experience with thoracic MRI.

Magnetic resonance imaging of hemorrhage

The magnetic resonance imaging (MRI) characteristics of evolving hemorrhage are discussed and compared with those of computed tomography (CT). Studies of 15 hematomas were undertaken in four mongrel dogs. The hematomas were created by the injection of autologous blood into the subcutaneous tissues of the thigh. The hematomas were studied serially with both MRI and CT. Pulse sequences included spin-echo (2100 msec TR, 40 and 80 msec TE) and inversion-recovery (2100 msec TR, 400 msec TI, 40 msec TE). Relaxation times (T1 and T2) were calculated in each case. CT values (H) were also obtained. In addition, 24 single and 14 serial scans of hemorrhage were obtained from 24 patients. MRI was performed on a 0.15-T resistive magnet scanner. T1 and T2 relaxation times and CT values decreased as the hematomas resolved. T1 and T2 relaxation times of intraparenchymal hemorrhage tended to remain elevated with time. MRI seems to be more sensitive than CT for the detection of hemorrhage, primarily because of superior contrast resolution.

Use of 131I-MIBG scintigraphy in the evaluation of suspected pheochromocytoma

Studies at the University of Michigan have shown that 131I-metaiodobenzylguanidine (131I-MIBG) is an effective agent for the diagnosis and localization of pheochromocytomas and paragangliomas. We conducted a study that confirmed and expanded that finding. From January 1983 to March 1984, 48 patients at our institution had 51 131I-MIBG scans during the workup of suspected sporadic or metastatic pheochromocytoma. Scintigrams were obtained after 500 microCI of 131I-MIBG had been administered intravenously. The final diagnosis (true-positive, false-negative, or false-positive result) was made at operation and pathologic examination. A true-negative diagnosis was confirmed by normal plasma and fractionated urinary levels of catecholamines and metabolites and, in most patients, computed tomography (CT). There were 20 true-positive studies (6 pheochromocytomas, 4 paragangliomas, and 10 metastatic or recurrent pheochromocytomas) and 24 true-negative studies. One patient with a suspected recurrent paraganglioma near the bladder had a false-positive 131I-MIBG scan (and also a false-positive (CT). Among six patients with false-negative scintigrams (three pheochromocytomas, one paraganglioma, and two metastatic lesions), one also had a false-negative CT. The overall sensitivity of 131I-MIBG scanning was 77%, specificity was 96%, and accuracy was 86%. This test is fairly sensitive in the workup of patients with known or suspected recurrent or metastatic pheochromocytoma. It may also be helpful in the evaluation of suspected sporadic pheochromocytoma when CT findings are normal.

CT of extracranial hemorrhage and hematomas

Computed tomography was used to examine 100 patients with extracranial hemorrhage. Of these patients, 29 had serial scans that allowed for the study of evolutionary changes. Operation, anticoagulation, and trauma were the prime etiologic factors. The most frequent sites included the retroperitoneum (27%), body wall or extremities (24%), peritoneal cavity (19%), and subcapsular (16%) and intraparenchymal (7%) locations. The computed tomographic features were carefully studied and documented. Age-related features included contrast-material extravasation, inhomogeneity, hematocrit effect, attenuation changes, lucent halo, pseudocapsule development, decreased size with time, peripheral calcification, and fascial plane thickening. Some of these features are indicative of hemorrhage but others are nonspecific. This report discusses all these findings and their usefulness in diagnosis and patient care.