Clinical and radiologic factors associated with pulmonary nodule etiology in organ transplant recipients.

Identifying clinical and radiographic factors that are associated with a specific etiology of pulmonary nodules (PNs) in solid-organ transplant (SOT) recipients might be helpful in guiding empiric therapy. Multivariable logistic regression was used to assess the relationship of clinical and radiographic variables to the etiology of PN in a retrospectively identified cohort of SOT recipients at a single transplant center. PNs in 55 SOT recipients (lung 15%, heart 22%, liver 42%, kidney 18% or kidney/pancreas 5%) were diagnosed at a mean of 1061 days post-transplant and were infectious in 31 of 55 (56%) (bacterial 22%, fungal 33%, viral 2%) and noninfectious in 24 of 55 (44%) [post-transplant lymphoproliferative disorder (PTLD) 25%, carcinoma 18%]. Radiographic 'consolidation' was independently associated with an infectious etiology (OR, 20.2, p < 0.01). Epstein-Barr virus seronegativity and lung transplant were each associated with PTLD (OR, 21.7, p < 0.01) and (OR, 36.6, p < 0.001), respectively. Diagnosis less than 90 days post-transplant was associated with Aspergillus infection (OR, 12.9, p = 0.007). Specific clinical and radiographic features are associated with specific etiologies of PNs in SOT recipients and might be useful for guiding empiric therapy while awaiting results of definitive diagnostic studies.

Pulmonary infections in immunocompromised hosts: the importance of correlating the conventional radiologic appearance with the clinical setting.

The lung is one of the most frequently involved organs in a variety of complications in the immunocompromised host. Among the pulmonary complications that occur in this kind of patient, infection is the most common and is associated with high morbidity and mortality. Although chest radiography and computed tomography (CT) are essential diagnostic tools, radiologists often have difficulty in establishing the correct diagnosis on the basis of radiologic findings alone. The reasons are that the immunocompromised host is potentially susceptible to infection from many different microorganisms and that radiologic findings are seldom specific for the detection of a particular pathogen. Experience has shown that a particular clinical setting predisposes patients to infection by particular pathogens. The setting comprises (a) the specific epidemiologic or environmental exposure, (b) the type of underlying immune defect, (c) the duration and severity of immune compromise, and (d) the progression rate and pattern of the radiologic abnormality. Correlating the radiologic appearance with the clinical setting can expedite diagnosis and appropriate therapy. In this review, the authors describe the clinical settings that are helpful in choosing the radiologic approach to treatment of the immunocompromised host who presents with suspected pulmonary infection.

Thoracic manifestations associated with advanced liver disease.

Advanced liver disease and portal hypertension may produce various intrathoracic complications that involve the pleural space, lung parenchyma, and pulmonary circulation. Dyspnea and arterial hypoxemia are the common clinical symptoms and signs in patients with such complications. In these patients, intrathoracic complications most often develop during the course of hepatic disease, but a few patients may be seen first with respiratory symptoms or radiographic abnormalities. Therefore, radiologists should be made aware of these disorders that occur in patients with chronic liver disease. In this article, the authors describe and illustrate the clinical and imaging spectrum of thoracic abnormalities associated with advanced liver disease and portal hypertension.

Talcosis associated with IV abuse of oral medications: CT findings.

OBJECTIVE: Our objective was to evaluate the CT appearance of talcosis associated with IV abuse of oral medications and to compare the findings of talcosis related to methylphenidate with those findings seen with other drugs. MATERIALS AND METHODS: The CT scans of 12 patients with talcosis (seven men, five women), 33-54 years old (mean age, 44 years), were analyzed retrospectively. Seven patients had abused methylphenidate; five patients had no history of abuse. The diagnosis of talcosis was made histologically in 11 patients and at funduscopy in one patient. CT was performed with 1- to 1.5-mm collimation (n = 10 patients) or 5- to 10-mm collimation (n = 2). RESULTS: The predominant abnormalities seen on CT consisted of a diffuse fine nodular pattern (n = 2), a combination of nodules and lower lobe panacinar emphysema (n = 3), and ground-glass attenuation (n = 2). Emphysema was the only abnormality seen in the remaining five patients (lower lobe panacinar, n = 4; upper lobe centrilobular, n = 1). No significant difference in the prevalence of nodules and ground-glass attenuation was seen between the methylphenidate and non-methylphenidate groups. Lower lobe panacinar emphysema was more common in methylphenidate abusers (six [86%] of seven patients) than in non-mnethylphenidate drug abusers (one [20%] of five, p<0.05, Fisher's exact test). CONCLUSION: The CT manifestations of talcosis consist of a fine micronodular pattern, ground-glass attenuation, and emphysema. A significantly increased prevalence of lower lobe panacinar emphysema is seen in IV drug addicts who abuse methylphenidate.

The accuracy of the clinical diagnosis of new-onset idiopathic pulmonary fibrosis and other interstitial lung disease: A prospective study.

STUDY OBJECTIVES: Presently, surgical (open or thoracoscopic) lung biopsy (SLB) is the gold standard for the diagnosis of new-onset idiopathic pulmonary fibrosis (IPF) and other interstitial lung diseases (ILDs). The accuracy of a clinical diagnosis of IPF and other subsets of ILD has never been established in prospective studies. We investigated the accuracy and validity of a clinical diagnosis of IPF and ILD other than IPF. DESIGN: Prospective, independent evaluation of patients and clinical data by an ILD expert, of chest radiographic and high-resolution computed tomography (HRCT) features by a chest radiologist, and of histologic features of lung biopsy by a pulmonary pathologist in consecutive patients referred for a diagnostic evaluation of ILD. SETTING: Tertiary university medical center with recognized expertise in management of ILD. PATIENTS: Community patients referred for further definitive diagnostic evaluation of new-onset, untreated nonspecific ILD. INTERVENTION: By comparing the histologic features of SLB in 59 patients consecutively referred for further diagnostic evaluation of new-onset ILD with the clinical and radiologic diagnoses, we determined the sensitivity and specificity of clinical diagnosis and radiologic diagnosis (based on chest radiograph and HRCT features alone) of IPF and ILD other than IPF. A specific clinical diagnosis was independently made by the ILD expert after a thorough clinical assessment that included evaluation of an HRCT scan and bronchoscopic findings. The chest radiographs and HRCT scans were separately reviewed by the chest radiologist, who made a radiologic diagnosis independently. All patients underwent SLB within a month of preoperative "clinical" diagnosis. The clinician's and radiologist's diagnoses were then compared with the gold standard of histologic diagnosis. MEASUREMENTS AND RESULTS: Prior to the clinical evaluation at our center, 85% of patients who underwent SLB had nondiagnostic transbronchial biopsy. The diagnosis of IPF and ILD other than IPF was accurately made by clinical features alone in 62% of cases. The correct radiographic diagnosis of non-IPF ILD was made in 58% of the cases. The sensitivity and specificity of the clinical diagnosis of ILD other than IPF were 88.8% and 40%, respectively. The sensitivity and specificity of the radiographic diagnosis of ILD other than IPF were 59% and 40%, respectively. However, the sensitivity and specificity of the diagnosis of IPF on clinical grounds were 62% and 97%, respectively. The sensitivity and specificity of the radiologic diagnosis of IPF were 78.5% and 90%, respectively. CONCLUSIONS: In a center with recognized expertise in the management of ILD, the specificity of diagnosis of new-onset IPF based on a thorough clinical assessment or HRCT features alone is very high (97% and 90%, respectively), but the sensitivity is low (62% and 78.5%, respectively). Thus, not all patients with new-onset IPF require SLB for diagnosis, but a diagnosis of IPF will be missed in nearly one third of new-onset IPF cases despite evaluation by experts. The relatively low sensitivity and specificity of the diagnosis of ILD other than IPF also emphasizes that an SLB is indicated in patients with ILD in whom the diagnosis is unclear.

A new view of pulmonary edema and acute respiratory distress syndrome.

The old division of lung edema into two categories--cardiogenic (hydrostatic) and noncardiogenic (increased permeability)--is no longer adequate. For instance, it fails to distinguish between the capillary leak caused by acute respiratory distress syndrome from that caused by interleukin-2 treatment. Further, it fails to account for the capillary leak ('stress-failure') that may accompany edema. A modern view of edema must recognize the natural barriers to the formation and spread of edema. These barriers are the capillary endothelium and the alveolar epithelium. Varying degrees of damage to them can account for the varying radiographic and clinical manifestations of lung edema. Thus, interleukin-2 administration causes increased endothelial permeability without causing alveolar epithelial damage. The result is lung edema that is largely confined to the interstitium, causing little hypoxia and clearing rapidly. However, acute respiratory distress syndrome, which is characterized by extensive alveolar damage, causes air-space consolidation, severe hypoxia, and slow resolution. Thus, a reasonable classification of lung edema requires at least four categories: 1) hydrostatic edema; 2) acute respiratory distress syndrome (permeability edema caused by diffuse alveolar damage); 3) permeability edema without alveolar damage; and (4) mixed hydrostatic and permeability edema. The authors emphasize the importance of the barriers provided by the capillary endothelium and the alveolar epithelium in determining the clinical and radiographic manifestations of edema. In general, when the alveolar epithelium is intact, the radiographic manifestations are those of interstitial (not air-space) edema; this radiographic pattern predicts a mild clinical course and prompt resolution.

Radiology of chronic obstructive pulmonary disease.

This article reviews the radiologic manifestations and complications of chronic obstructive pulmonary disease, particularly those seen in association with emphysema. Current concepts on the pathogenesis of chronic obstructive pulmonary disease are discussed and related to findings on high-resolution CT scan and histologic examinations. Controversial issues concerning the detection and grading of emphysema using radiologic and physiologic tests are also addressed.

Lung-volume reduction surgery for diffuse emphysema: radiologic assessment of changes in thoracic dimensions.

Patients with severe, diffuse emphysema may be candidates for pneumectomy (lung-volume reduction surgery, LVRS) to improve lung and respiratory muscle function. To identify candidates who might benefit from this surgery, it is necessary to understand how lung volumes and respiratory function are effected. In this article, the authors demonstrate a significant difference in lung size on chest radiographs obtained before and after surgery. Thirty-five of 71 consecutive patients undergoing LVRS had both preoperative and postoperative chest radiographs and pulmonary function tests available for retrospective review. Preoperative and postoperative measurements of lung height, transthoracic diameters, mediastinal width, heart size, diaphragmatic arc, and intercostal spaces were compared using paired t-tests. Radiographic measurements where also correlated with changes in lung volumes as measured by pulmonary function tests. Lung heights (right, left, mean lateral) and coronal diameter at the aortic arch were reduced after surgery (all p < 0.05). Forced vital capacity, forced expiratory volume in 1 second (FEV1), and vital capacity increased, and total lung capacity and residual volume decreased after surgery (all p < 0.05). Left lung height showed a significant correlation (p = 0.025) with FEV1; all other correlations between radiographic changes and pulmonary function test changes were not significant. The explanation for improved lung function in patients after LVRS is not completely clear and is probably multifactorial. Radiologic alterations reflect anatomic changes caused by surgery and support the theory that modifications of chest wall configuration occur and are likely responsible, in part, for improved symptomatology and respiratory function.

The hepatopulmonary syndrome: radiologic findings in 10 patients.

OBJECTIVE: The purpose of this study was to review the radiologic manifestations of the hepatopulmonary syndrome. MATERIALS AND METHODS: We retrospectively reviewed clinical records, chest radiographs, 99m Tc-macroaggregated albumin (MAA) perfusion lung scans, chest CT scans, and pulmonary angiograms of 10 patients with proven hepatopulmonary syndrome. RESULTS: Chest radiographs showed basilar, medium-sized (1.5-3.0 mm) nodular or reticulonodular opacities in all cases. CT was done in eight cases and showed basilar dilatation of lung vessels with a larger than normal number of visible branches. The vascular basis for these opacities was best appreciated on conventional CT scans of 10-mm sections. No individual arteriovenous malformations were seen on CT scans. High-resolution CT scans showed no evidence of interstitial fibrosis. 99mTc-MAA perfusion lung imaging, done in seven patients, showed pulmonary arteriovenous shunting in five. Contrast echocardiography confirmed intrapulmonary shunting in these five patients. Pulmonary angiography, done in four cases, showed subtle distal vascular dilatation in two and moderate dilatation with early venous filling in two but did not reveal any individual arteriovenous malformations. CONCLUSION: Chest radiographs in hepatopulmonary syndrome usually show bibasilar nodular or reticulonodular opacities. Conventional CT shows that these opacities represent dilated lung vessels. High-resolution CT is useful in excluding pulmonary fibrosis or emphysema as the cause of these opacities. 99mTc-MMA perfusion imaging or contrast echocardiography can be used to confirm intrapulmonary arteriovenous shunting.

Pneumomediastinum: old signs and new signs.

Pneumomediastinum, also known as mediastinal emphysema, represents extraluminal gas in the mediastinum. Pneumomediastinum can lead to pneumothorax, pneumopericardium, pneumoperitoneum, or pneumoretroperitoneum. There are many causes of pneumomediastinum (Table 1) and several radiographic signs: pneumopericardium, continuous diaphragm sign, continuous left hemidiaphragm sign, Naclerio's V sign, V sign at confluence of brachiocephalic veins, ring-around-the-artery sign, thymic spinnaker-sail sign, and extrapleural air sign. We review the common and uncommon signs of pneumomediastinum and present some new signs. We also address the problem of distinguishing pneumomediastinum from pneumothorax and pneumopericardium.

Intrathoracic granulocytic sarcomas.

Recent trends in the treatment of intrathoracic granulocytic sarcoma (IGS) call for an overview of its radiographic manifestations. Nine patients from our institution and a review of 41 from the literature provide the basis of our conclusions on the typical and atypical appearance of IGS. Of the nine patients with IGS, all had chest radiographs, five had computed tomographic (CT) scans, and one had magnetic resonance (MR) scans. Radiographic studies and medical records were examined to establish the site and appearance of IGS. Three cases were histologically proved; in the others, the diagnosis was based on clinical presentation and response to chemotherapy. The mediastinum was the most common site of involvement (six of nine cases). A focal mass or mediastinal widening was visible on chest radiographs, and a focal mass or diffuse infiltration or replacement of fat was visible on chest CT. Less common sites of involvement were the lungs (two cases), the pleura (two), the pericardium (two), and the hilar (two). Mediastinal or hilar mass or mediastinal widening is the characteristic finding in IGS. Less common manifestations such as pleural and pericardial effusions and lung opacities should be confirmed histologically, since fluid or tissue is readily accessible.

Respiratory compensation in projection imaging using a magnification and displacement model.

Respiratory motion during the collection of computed tomography (CT) projections generates structured artifacts and a loss of resolution that can render the scans unusable. This motion is problematic in scans of those patients who cannot suspend respiration, such as the very young or intubated patients. Here, the authors present an algorithm that can be used to reduce motion artifacts in CT scans caused by respiration. An approximate model for the effect of respiration is that the object cross section under interrogation experiences time-varying magnification and displacement along two axes. Using this model an exact filtered backprojection algorithm is derived for the case of parallel projections. The result is extended to generate an approximate reconstruction formula for fan-beam projections. Computer simulations and scans of phantoms on a commercial CT scanner validate the new reconstruction algorithms for parallel and fan-beam projections. Significant reduction in respiratory artifacts is demonstrated clinically when the motion model is satisfied. The method can be applied to projection data used in CT, single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI).

Correction of computed tomography motion artifacts using pixel-specific back-projection.

Cardiac and respiratory motion can cause artifacts in computed tomography scans of the chest. The authors describe a new method for reducing these artifacts called pixel-specific back-projection (PSBP). PSBP reduces artifacts caused by in-plane motion by reconstructing each pixel in a frame of reference that moves with the in-plane motion in the volume being scanned. The motion of the frame of reference is specified by constructing maps that describe the motion of each pixel in the image at the time each projection was measured; these maps are based on measurements of the in-plane motion. PSBP has been tested in computer simulations and with volunteer data. In computer simulations, PSBP removed the structured artifacts caused by motion. In scans of two volunteers, PSBP reduced doubling and streaking in chest scans to a level that made the images clinically useful. PSBP corrections of liver scans were less satisfactory because the motion of the liver is predominantly superior-inferior (S-I). PSBP uses a unique set of motion parameters to describe the motion at each point in the chest as opposed to requiring that the motion be described by a single set of parameters. Therefore, PSBP may be more useful in correcting clinical scans than are other correction techniques previously described.

Chest computed tomography display preferences. Survey of thoracic radiologists.

RATIONALE AND OBJECTIVES: The authors conducted a survey of dedicated thoracic radiologists and tabulated their preferences for reconstruction algorithm, display, and photography of computed tomography (CT) scans of the chest. METHODS: Data were derived from a mail survey of 343 active members of the Society of Thoracic Radiology and based on a set of 20 questions about the display and photography of chest CT scans. The response rate was 35.4%. RESULTS: There were 119 usable replies from 31 states and 8 countries. Although there was considerable variation, the questionnaire indicates that the "typical" dedicated thoracic radiologist, regardless of practice setting, uses a standard reconstruction algorithm for chest CT and prints images on a laser imager using the "sharp" setting with a 12-on-1 format. Window settings for evaluating the lung are window-width 1500 HU and window-level -600 HU. Window settings for evaluating the mediastinum are window-width 350 HU and window-level 40 HU. CONCLUSIONS: Although there is wide variation in the preferences used to display and photograph chest CT scans, most thoracic radiologists have similar display preferences.

Pulmonary lymphangitic carcinomatosis: chronicity of radiographic findings in long-term survivors.

OBJECTIVE: Long-term survival after development of pulmonary lymphangitic carcinomatosis is considered unusual. However, modern chemotherapy can result in surprising stability or only gradual progression of lymphangitic carcinomatosis. We evaluated the course of radiographic findings in 10 patients with chronic lymphangitic carcinomatosis. MATERIALS AND METHODS: Ten patients met our criterion of having lymphangitic carcinomatosis for at least 6 months. The primary tumor was a carcinoma of the breast in six cases, the ovary in two, the pancreas in one, and the skin in one. Serial radiographs (all cases) and CT scans (eight cases) were analyzed retrospectively. RESULTS: Survival with lymphangitic carcinomatosis ranged from 11 to 30 months (median, 13 months). With chemotherapy, the radiographic abnormalities and pulmonary symptoms initially regressed in six patients, progressed in two, and remained unchanged in two; the radiographic findings of lymphangitic carcinomatosis were progressing at the time of death in four patients. All patients had periods of at least 4 months of relative stability or slow progression of pulmonary radiographic abnormalities. Serial transbronchial biopsies in one case confirmed persistent lymphangitic carcinomatosis despite therapy, and autopsy disclosed persistent lymphangitic tumor in two others. CONCLUSION: Stability or slow progression of radiographic findings can occur in some patients with lymphangitic carcinomatosis. Therefore, chronicity of radiographic findings should not be taken as evidence against lymphangitic carcinomatosis as the cause of an interstitial abnormality in a patient with cancer.

Acute aortic dissection: typical and atypical imaging features.

Acute aortic dissection (AAD) is the most common emergency affecting the aorta. Noninvasive imaging allows prompt and reliable diagnosis of AAD and has largely supplanted aortography. However, atypical imaging features and diagnostic pitfalls can delay lifesaving therapy. An intimal flap is the characteristic feature of AAD. If there is flow within both lumina, typical imaging features are probably present. If the false lumen is thrombosed or there is no intimal tear to permit flow through the false lumen, a distinct intimal flap may not be present. Secondary signs of AAD include an intramural or periaortic acute thrombus, which manifests as a high-attenuation cuff or crescent on unenhanced computed tomographic scans. Other conditions that can reduce the conspicuity of the intimal flap include atypical configurations of the flap, such as seen with short dissections or with multiple false channels, in which case the flaps are complex. Finally, aortic anomalies may cause confusion.

The implantable pace-maker-cardioverter-defibrillator: radiographic aspects.

Safer and easier placement, recent approval by the U.S. Food and Drug Administration of several models, and increasing availability have expanded the use of implantable cardioverter-defibrillators (ICDs) for treatment of life-threatening ventricular tachyarrhythmia. Modern ICDs generally use a combination of two transvenously placed electrodes and one subcutaneous electrode; therefore, they do not require a thoracotomy for placement. The authors evaluated the radiographic aspects of one particular ICD--the pacemaker-cardioverter-defibrillator (PCD)--including the normal appearance and variations, confusing findings, and such complications as deformity of the subcutaneous patch electrode, lead fracture, and electrode malposition and migration. The PCD can also be combined with a preexisting, surgically placed automatic ICD or with a pacemaker. Familiarity with the PCD and other ICDs is essential, since the radiologist may be the first to recognize a complication that can render the device inoperative and leave the patient vulnerable to sudden death.