Practical applications of Mach band theory in thoracic analysis.

In this review, routine radiographs with computed tomographic (CT) correlation are used to demonstrate practical applications of Mach band theory in thoracic analysis. Mach bands represent optical psychophysiologic edge-enhancement phenomena produced by means of lateral inhibition in the retina of the eye. Visualization of Mach bands depends on a set of variables that involve primarily the contour and optical density of a structure at an interface relative to that of its surround. On the basis of their appearance, the bands are defined as positive (white) or negative (black). The concept of Mach bands contributes to a greater understanding of three-dimensional structures projected onto two-dimensional routine radiographic images of the thorax. Mach bands can help differentiate normal from abnormal anatomy and thus increase the diagnostic yield from such images. Mach bands can be seen on images that use transmitted or reflective light, including CT scout images (topograms) of the thorax.

Venous chest anatomy: clinical implications.

This article provides a practical approach to the clinical implications and importance of understanding the collateral venous anatomy of the thorax. Routine radiography, conventional venography, computed tomography (CT), and magnetic resonance (MR) imaging studies provide correlative anatomic models for the demonstration of how interconnecting collateral vascular networks within the thorax maintain venous stability at all times. Five major systems comprise the collateral venous network of the thorax (Fig. 1). These include the paravertebral, azygos-hemiazygos, internal mammary, lateral thoracic, and anterior jugular venous systems (AJVS). The five systems are presented in the following sequence: (a) a brief introduction to the importance of catheter position and malposition in understanding access to the thoracic venous system, (b) the anatomy of the azygos-hemiazygos systems and their relationship with the paravertebral plexus, (c) the importance of the AJVS, (d) 'loop' concepts interconnecting the internal mammary and azygos-hemiazygos systems by means of the lateral thoracic and intercostal veins, and (e) the interconnecting venous networks on the thoracic side of the thoracoabdominal junction. Certain aspects of the venous anatomy of the thorax will not be discussed in this chapter and include (a) the intra-abdominal anastomoses between the superior and inferior vena cavae (IVC) via the internal mammary, lateral thoracic, and azygos-hemiazygos systems (beyond the scope of this article), (b) potential collateral vessels involving vertebral, parascapular, thyroidal, thymic, and other smaller veins that might anastomose with the major systems, and (c) anatomic variants and pitfalls that may mimic pathologic conditions (space limitations).

Prospective study of combination chemotherapy with cyclophosphamide, doxorubicin, and cisplatin for unresectable or metastatic malignant pleural mesothelioma.

BACKGROUND: This study was designed to determine the efficacy and side effects of a combination of cyclophosphamide (C), doxorubicin (D), and cisplatin (P) in patients with inoperable, unresectable, or metastatic malignant pleural mesothelioma. METHODS: Twenty-three patients with unresectable or metastatic malignant pleural mesothelioma were entered onto the study. The median age was 62 years (range, 42-74 years); there were 20 males and 3 females; the median performance status was 1 (Zubrod's scale). The histologic types included epithelial (14 patients), sarcomatoid (4 patients), unclassified (4 patients), and mixed type (1 patient). Twenty patients were known to have been exposed to asbestos and 3 were not. All patients were treated with the following starting dose of chemotherapy: a cycle comprised of C, 500 mg/m2 intravenously, day 1; D, 50 mg/m2 intravenously, day 1; and P, 80 mg/m2 intravenously, day 1 every 3 weeks. The cisplatin dose was reduced to 50 mg/m2 for the subsequent courses. For the assessment of tumor response, all patients had computed tomography scans of the chest after each three cycles of chemotherapy. RESULTS: Overall, 7 of 23 patients (30%) had partial responses (durations of responses [weeks]: 158+, 91+, 70+, 41+, 40, 39, 25), three had minor responses, and 14 had stable or progressive disease. One partial responder later underwent surgical resection and no viable tumors cells were found in the pathologic specimen. All patients have stopped treatment, and eight are still alive. The most common side effect was granulocytopenia (grade 4, 52%; grade 3, 17%). Other hematologic side effects were modest. Nonhematologic side effects included mild to moderate nausea and vomiting, neutropenic fever (three patients), peripheral neuropathy (one patient), and congestive heart failure (one patient). The overall median duration of survival was 60 weeks. CONCLUSION: Combination chemotherapy with CDP was well tolerated and had significant activity against unresectable or metastatic malignant pleural mesothelioma. The median duration of responses was 60 weeks; however, the survival rate was far from satisfactory. Continued development of new approaches including the biologic understanding of tumor development and testing new agents is warranted.

Helical CT angiography with multiplanar reformation: techniques and clinical applications.

The technique and potential clinical applications of multiplanar reformation (MPR) of imaging data from helical computed tomography (CT) to display images of the blood vessels in the abdomen and the thorax are described. Helical CT was performed following bolus intravenous contrast material enhancement in patients with suspected tumor involvement of vessels in various regions of the body. The axial images were stacked to form a volume of imaging data from which a plane could be selected to display the desired vascular image in a two-dimensional format. Various techniques were used to change the image plane so that different vessels in different regions of the body could be displayed, including the splanchnic vessels around the pancreas, the portal veins and hepatic artery in the porta hepatis, the renal vessels, and the venae cavae and aorta. Rotation from a coronal or sagittal plane was necessary to display most vessels. The technique is practical and reproducible, but it requires that the operator be knowledgeable about vascular anatomy. Helical CT angiography with MPR has the potential to display vascular images that are similar to angiograms.

Diagnosis of injuries of the aorta and brachiocephalic arteries caused by blunt chest trauma: CT vs aortography.

OBJECTIVE: The purpose of this study was to evaluate the role of chest CT in the triage of patients with potential injuries of the aorta and brachiocephalic arteries caused by blunt trauma and to test the value of chest CT scans in limiting the number of screening aortograms. SUBJECTS AND METHODS: A prospective study was done with 107 patients who were examined because of possible laceration of the aorta or brachiocephalic vessels. Chest radiographs were obtained in 107 patients, aortograms in 105, and chest CT scans in 90. This evaluation concentrates on the 88 patients who had both CT and aortography. Findings on CT scans were categorized as normal, equivocal, suggestive of, subtly positive for, or grossly positive for mediastinal hematoma. RESULTS: Findings on CT scans were considered normal in 18 patients. Sixteen had normal aortographic findings. Two of the 18 had clinical follow-up without aortography. Findings on CT scans were considered equivocal in 25 patients, suggestive of hematoma in 13, subtly positive for hematoma in 24, and grossly positive for hematoma in 10. Subsequent aortography showed injuries in four patients who had abnormal CT findings. Nineteen other patients had aortography because of grossly abnormal findings on chest radiographs, and one aortic injury was detected. CONCLUSION: The value of chest CT as a preliminary procedure to avoid thoracic aortography in patients with blunt trauma was limited in our series. Chest CT scans with normal findings effectively exclude aortic/brachiocephalic injury; however, only about 25% of our patients had chest CT scans with unequivocally normal findings, and most patients required further evaluation with aortography.

Amiodarone pulmonary toxicity: a multidisciplinary review of current status.

Amiodarone, a benzofuran derivative, has proven useful in the control of serious cardiac arrhythmias. We reviewed the English language medical literature to characterize clinical, radiographic, scintigraphic, pathologic, diagnostic, and prognostic data concerning amiodarone pulmonary toxicity. Our review showed that features consistent with amiodarone pulmonary toxicity include exertional dyspnea, fever, and high sedimentation rates, usually in patients taking larger maintenance doses. Positive findings on gallium scan, foamy alveolar macrophages on lung biopsy or bronchoalveolar lavage, and resolution of abnormal chest roentgenogram upon withdrawal of amiodarone and/or institution of corticosteroid therapy support a diagnosis of amiodarone pulmonary toxicity. Conversely, maintenance doses of 400 mg or less daily, normal lung diffusing capacity and bronchoalveolar lavage or lung biopsy specimens without foamy alveolar macrophages are features that make amiodarone pulmonary toxicity unlikely. Amiodarone pulmonary toxicity should be considered in any patient who has new or clinical worsening of respiratory symptoms and/or abnormalities on chest roentgenogram. Congestive heart failure is often present in these patients and must be excluded before a diagnosis of amiodarone pulmonary toxicity can be considered. Amiodarone pulmonary toxicity also needs to be distinguished from pulmonary infection. Therefore, amiodarone pulmonary toxicity remains a clinical diagnosis relying upon a composite of clinical, radiographic, and histopathologic findings.

The postlobectomy chest: anatomic considerations.

The authors present a systematic review of the changes that occur in pulmonary and extrapulmonary anatomy as the result of lobar collapse or resection. Differences in the changes produced by lobectomy and lobar collapse are noted.

Imaging primary lung cancers, pleural cancers, and metastatic disease.

Evaluation of primary lung cancers, pleural cancers, and metastases should be based on the TNM system. The optimal selection of imaging modalities can be difficult, and there is no universal agreement on the approach to the workup. Diagnostic pathways can provide guidelines for radiologic imaging sequencing based on the TNM system (Figs. 21-23). No algorithm, however, can fit all situations, and each cancer may require a distinct approach.

Concepts in computed tomography of the thorax.

A number of concepts in the CT evaluation of the thorax have been reviewed. The concepts have been presented through anatomic images generated on a specific CT system, but any equivalent system could have produced similar images. The important conclusions derived as a result of this review are: 1. Slice thickness, volume averaging and volume sampling are interrelated. Slice thickness and the orientation and inherent subject contrast of the anatomy to be studied usually determine the quality of the image obtained. 2. Thin section imaging (i.e., 5 mm and especially 1.5 mm) can demonstrate thoracic anatomy rarely (if ever) observed on thicker images (i.e., 10 mm). Although impractical for general analysis, thin section imaging provides insight into the potential limitations of a standard approach to thoracic evaluation. 3. CT analysis of the normal anatomy of the pericardium is incomplete. Although pathology related to the pericardium has been presented in the literature, more work is required to define: 1, the relationship, on CT, of the pericardium to structures within its confines; 2, abnormalities within the mediastinum that may affect the pericardium, and 3, lesions in the lung that may invade the mediastinum and pericardium. 4. The excellent contrast sensitivity of CT (aided by iodine infusion or bolus injection techniques and dynamic scanning) does not suffice to resolve certain problems in thoracic analysis. Extrapleural signs, the concept of invasion versus abutment, and the discrimination of benign from malignant mediastinal nodes continue to present diagnostic dilemmas in CT analysis of the thorax. 5. Interesting cases provide models for demonstrating CT pitfalls, mimics, and rarities. CT can be a valuable tool in resolving diagnostic dilemmas in some cases but creates dilemmas in others. 6. CT reformation images of the thorax can be dynamically generated on the scanner console. This hands-on technique can be a valuable tool for teaching anatomy in resident training programs.

Pulmonary nodules: detection of calcification by linear and pluridirectional movement in tomographic study.

Calcification within solitary pulmonary nodules (1-2 cm range) was demonstrated by conventional tomography in a group of 20 patients. Each patient had a combined tomographic examination consisting of 15 degrees linear movement followed by 34 degrees hypocycloidal movement. Linear tomography was superior to pluridirectional tomography in 19 cases for visualization of calcium within the nodule. The results are attributed to differences in contrast sensitivity and "blur" phenomena between the two tomographic movements. This study, although comparing a specific linear movement with a specific pluridirectional movement, provides insight into the differences between tomographic techniques for a given task.

Pulmonary pseudolymphoma.

Pseudolymphomas of the lung are extremely rare with approximately 30 cases reported in the literature. Histologically it may be impossible to distinguish a benign pseudolymphoma from a malignant lymphoma. Immunoperoxidase staining has been proposed to help predict the benign or malignant potential of these conditions. Results thus far have been inconclusive, but a monoclonal pattern has tended to predict malignant potential. We have reported a pulmonary pseudolymphoma that failed to stain with the immunoperoxidase technique due to improper tissue fixation. After four years of clinical follow-up, the patient remains disease free.

Mediastinal impressions on the dilated esophagus.

This article explores how the mediastinum accommodates a significantly dilated esophagus, using achalasia as an anatomic model. This accommodation introduces the concepts of vascular tethering and the paratracheal esophagus as part of a unifying theory of "the path of least resistance." Practical examples demonstrate the importance of understanding these concepts in any disease involving esophageal dilatation.

Tomography of the pulmonary hili. Anatomical reassessment of the conventional 55 degrees posterior oblique.

Classic anatomical drawings of the pulmonary hili based on conventional 55 degrees posterior oblique tomograms must be modified to include the superior pulmonary veins, which can be more prominent in oblique projections than in anteroposterior views. Inadequate understanding of the limitations of conventional tomography in soft-tissue analysis, combined with simplistic modeling of hilar anatomy in fixed oblique orientations such as 55 degrees, can lead to errors in diagnosis.

Endobronchial non-Hodgkin's lymphoma.

Four patients with endobronchial non-Hodgkin's lymphoma are presented. Although endobronchial Hodgkin's disease is not uncommon, endobronchial non-Hodgkin's lymphoma is extremely rare. All patients had disseminated disease at the time of their endobronchial involvement. Chest radiographs revealed hilar masses and/or varying degrees of lobar collapse in each case. Two had multiple endobronchial lesions. Three patients died within two years of the diagnosis of endobronchial disease. The fourth patient is currently undergoing chemotherapy for disseminated disease. Lobar collapse in a patient with non-Hodgkin's lymphoma should include endobronchial involvement in the differential diagnosis. Therapy should include chest radiation in an attempt to re-expand the collapsed lung lobes and systemic chemotherapy. Prognosis is guarded due to disseminated disease at the time of diagnosis.

Pulmonary arteriovenous fistula simulating a vanishing tumor.

In a patient with an asymptomatic left upper lobe pulmonary arteriovenous fistula, preoperative chest roentgenograms simulated bronchogenic carcinoma, but no overt feeding vessel was demonstrated. Intraoperatively no lesion could be palpated. Postoperative evaluation revealed a pulmonary arteriovenous fistula. This entity should be considered in the differential diagnosis of single or multiple pulmonary nodules. Careful review of chest roentgenograms for feeding arteries, or draining veins, and observation under fluoroscopy for changing size will aid in diagnosis, and potentially avoid bronchoscopy and possible transbronchoscopic biopsy of these vascular lesions.