Static end-expiratory and dynamic forced expiratory tracheal collapse in COPD

AIM

To determine the range of tracheal collapse at end-expiration among chronic obstructive pulmonary disease (COPD) patients and to compare the extent of tracheal collapse between static end-expiratory and dynamic forced-expiratory multidetector-row computed tomography (MDCT).

MATERIALS AND METHODS

After institutional review board approval and obtaining informed consent, 67 patients meeting the National Heart, Lung, and Blood Institute (NHLBI)/World Health Organization (WHO) Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria for COPD were sequentially imaged using a 64-detector-row CT machine at end-inspiration, during forced expiration, and at end-expiration. Standardized respiratory coaching and spirometric monitoring were employed. Mean percentage tracheal collapse at end-expiration and forced expiration were compared using correlation analysis, and the power of end-expiratory cross-sectional area to predict excessive forced-expiratory tracheal collapse was computed following construction of receiver operating characteristic (ROC) curves.

RESULTS

Mean percentage expiratory collapse among COPD patients was 17 ± 18% at end-expiration compared to 62 ± 16% during forced expiration. Over the observed range of end-expiratory tracheal collapse (approximately 10-50%), the positive predictive value of end-expiratory collapse to predict excessive (≥80%) forced expiratory tracheal collapse was <0.3.

CONCLUSION

COPD patients demonstrate a wide range of end-expiratory tracheal collapse. The magnitude of static end-expiratory tracheal collapse does not predict excessive dynamic expiratory tracheal collapse.

Subcarinal collection following mediastinoscopy: a normal post-procedural CT finding

AIM

To determine the frequency with which a subcarinal collection is present at computed tomography (CT) following mediastinoscopy and to determine the CT features of the collection.

MATERIALS AND METHODS

All patients who underwent uncomplicated mediastinoscopy during a 1-year period were retrospectively identified. This list was cross-referenced to determine those patients who also underwent CT within 15 days after the procedure. Each post-mediastinoscopy CT examination was assessed in consensus by three fellowship-trained thoracic radiologists for the presence of subcarinal abnormalities, which were also characterized in terms of their size and density. Additional CT findings were recorded, including tracheobronchial wall thickening, paratracheal collections, mediastinal fat stranding, and mediastinal air.

RESULTS

The study cohort included 10 patients (seven men and three women) with mean age of 65 years (range 49-81 years). CT was performed a mean of 11 days following mediastinoscopy. The most common CT finding was an oval subcarinal collection in nine of 10 cases (size 1.1-3.2 cm). In all nine cases, the subcarinal collections were consistently lower in attenuation than the subcarinal lymph node in the same region on the pre-procedure CT examination. Other CT findings included anterior tracheobronchial wall thickening (n=7); paratracheal collection (n=6); mediastinal fat stranding (n=6); and mediastinal air in (n=4) cases.

CONCLUSION

A subcarinal collection was identified in 90% of cases following mediastinoscopy. Its rapid development and characteristic appearance help to distinguish it from a lymph node.

T1-Maps und O2-verstärkte MRT der erkrankten Lunge

PURPOSE

Gas exchange is the primary function of the lung and the transport of oxygen plays a key role in pulmonary physiology and pathophysiology.

MATERIALS AND METHODS

Molecular oxygen is weakly paramagnetic, so that an increase in oxygen concentration results in shortening T1 relaxation time and thus increasing signal intensity in T1 weighted images. The calculation of parameter maps may allow deeper insights into relaxation mechanisms. T1 maps based on a snapshot FLASH sequence obtained during the inhalation of various oxygen concentrations allow the creation of an oxygen transfer function, providing a measurement of local oxygen transfer. T1 weighted single shot TSE sequences demonstrate the signal changing effects during inhalation of pure oxygen.

RESULTS

The average of the mean T1 values over the entire lung during inspiration was 1,199+/-117 ms, the average of these values during expiration was 1,333+/-167 ms. T1 maps of patients with emphysema and lung fibrosis show fundamentally different values and respiratory dependence compared to healthy individuals. Oxygen enhanced MR has the potential to assess reduced diffusion capacity and decreased transport of oxygen in patients with emphysema and cystic fibrosis.

DISCUSSION

Results published in the literature indicate that T1 mapping and oxygen enhanced MR are promising new methods in functional imaging of the lung.

Computed tomography assessment of lung structure and function in pulmonary edema

By definition pulmonary edema is an abnormal accumulation of water in the lung. Consequently, the computed tomography (CT) appearance of pulmonary edema reflects the sequence of this accumulation. In early hydrostatic pulmonary edema, CT shows vascular engorgement and peribronchovascular cuffing that increases with the severity of edema and that is associate in late stage, with consolidations. In acute respiratory distress syndrome (ARDS), CT shows the proportion of injured parenchyma and depicts associated alterations as parenchymal infiltrate and consolidation, pleural effusion, pneumothorax. These merely morphological findings can be complemented with data from objective CT analysis of the lung parenchyma. Indeed CT can assess lung water noninvasively. Correlated with hydrodynamic parameter, these objective measurements show that the increase of lung density parallels parenchymal fluid overload. These data also show that the occurrence of ground glass opacities can precede the hemodynamic evidence of edema.

MR ventilation-perfusion imaging of human lung using oxygen-enhanced and arterial spin labeling techniques

Magnetic resonance ventilation-perfusion (V/Q) imaging has been demonstrated using oxygen and arterial spin labeling techniques. Inhaled oxygen is used as a paramagnetic contrast agent in ventilation imaging using a multiple inversion recovery (MIR) approach. Pulmonary perfusion imaging is conducted using a flow-sensitive alternating inversion recovery with an extra radiofrequency pulse (FAIRER) technique. A half Fourier single-short turbo spin echo (HASTE) sequence is used for data acquisition in both techniques. V/Q imaging was performed in ten of the twenty volunteers, while either ventilation or perfusion was imaged in the other ten. This V/Q imaging scheme is completely noninvasive, does not involve ionized radiation, and shows promising potential for clinical use in the diagnosis of lung diseases such as pulmonary embolism.

Lung manifestation in asymptomatic patients with primary Sjögren syndrome: assessment with high resolution CT and pulmonary function tests

The authors studied 37 consecutive patients with primary Sjögren syndrome and normal chest radiographs. Thin-section CT images were analyzed using a semiquantitative grading system. The presence, distribution, and severity of 9 morphologic parameters were assessed. In 34 patients, CT findings were correlated to pulmonary function tests (PFTs). Abnormal high resolution CT (HRCT) findings were seen in 24 of 37 patients (65%): interlobular septal thickening, n = 9; micronodules, n = 9; ground glass attenuation n = 4; parenchymal cysts, n = 5. Intralobular opacities, honey combing, bronchial wall thickening, bronchiectasis, and pleural irregularities were less frequent. Both HRCT and PFTs were normal in 10 patients. Computed tomography was normal in four patients with PFTs that indicated the presence of small airway disease. High resolution CT abnormalities were found in seven patients with normal PFT. The overall correlation between HRCT and PFTs was poor. High resolution CT and PFTs appear to be sensitive for both the early detection of parenchymal abnormalities and a decreases in lung function in asymptomatic patients with primary Sjögren syndrome. However, abnormal HRCT findings do not necessarily indicate a substantial alteration in PFTs.

Pulmonary lymphangiomyomatosis mimicking Langerhans cell histiocytosis

The authors describe a patient with histologically confirmed pulmonary lymphangiomyomatosis and thin-section computed tomography findings mimicking Langerhans cell histioctytosis. The description emphasizes the nonspecificity of the computed tomography findings in this patient. This report also suggests that the computed tomography diagnosis of lymphangioleiomyomatosis can be difficult at an early stage of the disease and should be complemented by biopsy verification.

Cardiopulmonary resuscitation performed by bystanders does not increase adverse effects as assessed by chest radiography

Important adverse effects of bystander cardiopulmonary resuscitation (CPR) are well known. We describe the number of nonmedical professional CPR-related complications in patients surviving cardiac arrest, as assessed by chest radiograph. Within 2 yr, all consecutive patients admitted to the department of emergency medicine at a university hospital who had a witnessed, nontraumatic, normothermic cardiac arrest were studied. Radiologically evaluated adverse effects were compared with Mann-Whitney U-tests between patients who received bystander basic life support (Bystander group) and patients who did not receive bystander basic life support before advanced life support was started (ALS group). For assessment of bystander CPR-associated complications, chest radiographs were used. Of 224 patients, 173 were eligible. The median age was 58 yr (interquartile range, 51-71 yr), and 126 patients (73%) were men. The incidence of adverse effects associated with assisted-ventilation maneuvers and external chest compressions did not differ significantly between groups (severe gastric insufflation, 17% vs 18% between the Bystander group [n = 59] and the ALS group [n = 96], respectively; suspicion of aspiration, 22% vs 17%, respectively; soft tissue emphysema, 2% vs 1%, respectively; and serial rib fractures, 8% vs 8%, respectively). CPR administered by nonmedical personnel did not increase the number of life support-related adverse effects in patients surviving cardiac arrest as assessed by means of chest radiograph on admission.

IMPLICATIONS

Complications related to cardiopulmonary bypass (CPR) are not increased when CPR is administered by nonmedical personnel, as assessed by chest radiograph. These data may be valuable in motivating lay people to perform basic life support.

Displacement of coils into the lung during embolotherapy: clinical importance and follow-up with helical CT

RATIONALE AND OBJECTIVES

The authors performed this study to evaluate the clinical importance and computed tomographic (CT) appearance of coils displaced into the lung during embolotherapy.

MATERIALS AND METHODS

The authors retrospectively studied clinical charts and serial chest images from 25 consecutive patients after coil embolization. Chest radiography was performed in all patients, whereas helical chest CT was performed only in patients in whom dislocated coils were visible on chest radiographs. Coils were applied for the treatment of peripheral arteriovenous (AV) malformations and fistulas (n = 9), renal AV malformations or fistulas (n = 8), and primary or secondary tumors (n = 8). Clinical charts were analyzed for short- and long-term symptoms; chest radiographs and CT scans were reviewed for signs indicative of pulmonary infarction.

RESULTS

None of the patients had clinical symptoms suggestive of pulmonary infarction. In two of the 25 patients (8%), displaced coils were seen in the pulmonary vasculature at chest radiography; these patients had been treated for renal AV fistula and peripheral AV fistula, respectively. One patient had two coils in the left hemithorax (upper and lower lobe), and the other patient had two coils in the right hemithorax (middle lobe). Neither of the patients had abnormalities suggestive of pulmonary infarction at helical CT.

CONCLUSION

Chest radiography can help confirm the presence of coils displaced to the pulmonary vasculature during embolotherapy. Helical CT can also help rule out the presence of coil-associated pulmonary infarction.

Effect of lung inflation on arterial spin labeling signal in MR perfusion imaging of human lung

The effect of lung inflation on arterial spin-labeling signal in lung perfusion is investigated. Arterial spin-labeling schemes, called alternation of selective inversion pulse (ASI) and its hybrid (HASI), which uses blood water as an endogenous, freely diffusible tracer, were applied to magnetic resonance (MR) perfusion imaging of the lung. Perfusion-weighted images of the lung from nine healthy volunteers were obtained at different time delays. There was a significant signal difference in ASI images acquired at different respiratory phases. Greater signal enhancement has been observed when the volunteers performed breath holding on end expiration than on end inspiration. This is in agreement with the normal physiologic effect of lung inflation on the pressure-flow relationship of pulmonary vasculature. ASI and HASI perfusion-weighted images show similar lung features and image quality. Preliminary results from pulmonary embolism patients indicate that arterial spin labeling is sensitive for the detection of areas of perfusion deficit. J. Magn. Reson. Imaging 2001;13:954-959.

Spiral CT of the lung in children with malignant extra-thoracic tumors: distribution of benign vs malignant pulmonary nodules

The purpose of this paper is to clarify the distribution of benign vs malignant pulmonary nodules which are seen on spiral CT in children with malignant extra-thoracic solid tumors. Seventy-four children with known solid, extra-thoracic tumors underwent spiral CT of the chest. According to the initial and follow-up (interval 9.2+/-4.7 months) findings, the children were graded into four groups: I = normal; II = solitary nodule unchanged at follow-up; III = multiple nodules with one or more than one unchanged at follow-up; and IV = solitary or multiple nodules all changed at follow-up. Nodules without change at follow-up were regarded as benign. Forty-nine children did present with normal pulmonary CT exams. In 7 cases solitary pulmonary nodules were found unchanged (group II) at follow-up and in 2 cases (group III) some of the nodules were stationary. Thus, 12% (9 of 74) presented with at least one pulmonary nodule that did not change at follow-up. Solitary nodules (in groups II and IV) with a diameter <5 mm were in 70 % (7 of 10) unchanged at follow-up and regarded as benign. In children with known solid extra-thoracic tumors at initial presentation, 70% of solitary nodules ( <5 mm) may be benign. To avoid overstaging, smaller solitary nodules must not automatically be regarded as metastases.

Bronchiolitis obliterans syndrome in heart-lung transplant recipients: diagnosis with expiratory CT

PURPOSE

To determine the test performance and longitudinal evolution of air trapping for diagnosing bronchiolitis obliterans syndrome (BOS).

MATERIALS AND METHODS

Over 7 years, 111 combined inspiratory and expiratory computed tomographic examinations were performed in eight healthy control subjects and 38 heart-lung transplant recipients. Functional impairment was assessed with the BOS classification. Receiver operating characteristic (ROC) analysis was performed to determine the optimal threshold of air trapping to distinguish between patients with and those without BOS and to compute sensitivity and specificity for diagnosing BOS.

RESULTS

The extent of air trapping increased with BOS severity (P =.001). A threshold of 32% of air trapping is optimal for distinguishing between patients with and those without BOS and provides a sensitivity of 83%, a specificity of 89%, and an accuracy of 88%. The prevalence of BOS and positive predictive value of air trapping increased with postoperative time, but the negative predictive value of air trapping remained high throughout the study. Patients without BOS who had air trapping exceeding 32% of the parenchyma were at significantly increased risk of developing BOS (P =.004).

CONCLUSION

At the threshold of 32%, air trapping is sensitive, specific, and accurate for diagnosing BOS. Patients with air trapping below 32% are unlikely to have BOS. Air trapping exceeding 32% may be an early indicator of future BOS.

Ultrafast MR grid-tagging sequence for assessment of local mechanical properties of the lungs

While MR imaging with tagged magnetization has shown great utility in the study of muscle mechanics, the evaluation of pulmonary mechanics has long been hindered by the technical difficulties in MR imaging of lung parenchyma. In this study, a fast MR grid-tagging technique is described for dynamic assessment of regional pulmonary deformation. The method is based on a fast FLASH sequence with short TR and short TE. Tagging was achieved by using double DANTE pulse train or inversion pulses. Our results show that this technique is able to detect changes of the tagging grid caused by physiological deformation of the lung. Quantitative analysis of the data shows that this method is capable of assessing local pulmonary mechanics. The application of this technique could improve our understanding of ventilatory control, and thus provide a unique metric for assessing pulmonary disorders. Magn Reson Med 45:24-28, 2001.

Early pulmonary involvement in ankylosing spondylitis: assessment with thin-section CT

AIM

To determine the frequency and the distribution of early pulmonary lesions in patients with ankylosing spondylitis (AS) and a normal chest X-ray on thin-section CT and to correlate the CT findings with the results of pulmonary function tests and clinical data.

MATERIALS AND METHODS

Twenty-five patients with clinically proven AS and no history of smoking underwent clinical examinations, pulmonary function tests (PFT), chest radiography, and thin-section CT. Four of 25 patients (16%), who had obvious signs on plain films suggestive of pre-existing disorders unrelated to AS were excluded.

RESULTS

Fifteen of 21 patients (71%) had abnormalities on thin-section CT. The most frequent abnormalities were thickening of the interlobular septa in seven of 21 patients (33%), mild bronchial wall thickening in (6/21, 29%), pleural thickening and pleuropulmonary irregularities (both 29%) and linear septal thickening (6/21, 29%). In six patients there were no signs of pleuropulmonary involvement. Eight of 15 patients (53%) with abnormal and four of six patients (67%) with normal CT findings revealed mild restrictive lung function impairment.

CONCLUSION

Patients with AS but a normal chest radiograph frequently have abnormalities on thin-section CT. As these abnormalities are usually subtle and their extent does not correlate with functional and clinical data, the overall routine impact of thin-section CT in the diagnosis of AS is limited.

Imaging pulmonary blood flow and perfusion using phase-sensitive selective inversion recovery

A technique is described for imaging pulmonary blood flow using a phase-sensitive selective inversion recovery (PS-SIR) sequence. PS-SIR image reconstruction provides excellent contrast, differentiating fully relaxed inflowing blood from inverted blood and lung tissue. The magnetization of the inverted tissues remains negative at any inversion delay less than that at which the magnetization of the lung tissue is nulled, whereas that of the fully relaxed inflowing blood is always positive. Pulmonary blood flow can be observed by tracking the propagation of the pixels with positive values. Five healthy volunteers were imaged. The normal pattern of blood flow advancing from the central arteries toward the peripheries and into the lung parenchyma with return toward the center via draining veins was depicted. The method offers promise for evaluating pulmonary blood flow without the need for image subtraction or contrast administration. Magn Reson Med 43:793-795, 2000.

Multiple inversion recovery MR subtraction imaging of human ventilation from inhalation of room air and pure oxygen

The feasibility of MR subtraction imaging of lung ventilation using air against oxygen using a multiple inversion recovery half-Fourier single-shot turbo spin echo (MIR-HASTE) sequence was investigated. Eight healthy, nonsmoking volunteers (3 males, 5 females; from 27 to 48 years of age) were studied on a 1.5 T MR unit. The ventilation image was obtained from the subtraction of the images acquired with the subject inhaling room air and 100% oxygen. By suppressing the signal from subcutaneous fat and thoracic muscle, MIR-HASTE improved the subtraction of signal arising from background tissues. Lung parenchyma, pulmonary veins, descending aorta, spleen, and kidney showed high signal difference, but pulmonary arteries exhibited minimal signal difference. Because of minimal signal change in the pulmonary arteries after inhalation of 100% oxygen, the average signal decreases in the left and right lungs including hilus and periphery amounted to only 19.4+/-4.5 and 20.2+/-3.4%, respectively, compared with regional averages of 23.6+/-5.4 and 24.1+/-3.1% for both lung peripheries alone. Magn Reson Med 43:913-916, 2000.

CT and MR imaging of generalized cystic lymphangiomatosis in pediatric patients

OBJECTIVE

The aim of this study was to describe the spectrum of abnormalities seen in generalized cystic lymphangiomatosis as shown by CT and MR imaging and to correlate these findings to gross pathology.

CONCLUSION

MR imaging and CT may substantially broaden visualization of the spectrum of abnormalities seen in generalized cystic lymphangiomatosis by revealing the complete extent of disease and, thus, may contribute to clinical management of the disease by preventing initial misdiagnosis.

Improved uniformity of aortic enhancement with customized contrast medium injection protocols at CT angiography

PURPOSE

To compare the uniformity of aortoiliac opacification obtained from uniphasic contrast medium injections versus individualized biphasic injections at computed tomographic (CT) angiography.

MATERIALS AND METHODS

Thirty-two patients with an abdominal aortic aneurysm underwent CT angiography. In 16 patients (group 1), 120 mL of contrast material was administered at a flow rate of 4 mL/sec. In the other 16 patients (group 2), biphasic injection protocols were computed by using mathematic deconvolution of each patient's time-attenuation response to a standardized test injection. Attenuation uniformity was quantified as the "plateau deviation" of enhancement values, which were calculated as the SD of the time-contiguous attenuation values observed during the 30-second scanning period.

RESULTS

Group 2 patients received between 77 and 165 mL (mean, 115 mL) of contrast medium. Initial flow rates ranged from 4.1 to 10.0 mL/sec (mean, 6.8 mL/sec) for the first 4-6 seconds; continuing flow rates ranged from 2.0 to 4.8 mL/sec (mean, 3.1 mL/sec) for the remaining 24-26 seconds. The plateau deviation was significantly smaller in group 2 patients (19 HU) versus group 1 patients (38 HU, P <.001).

CONCLUSION

At CT angiography, tailored biphasic injections led to more uniform aortoiliac enhancement, compared with standard uniphasic injections of contrast medium.

Blood clots mimicking peripheral intrabronchial tumors in patients with hemoptysis: CT and bronchoscopic findings

We report radiographic and clinical findings in two cigarette-smoking patients presenting with hemoptysis. On CT, both patients had peripheral intrabronchial masses together with parenchymal opacities. Bronchoscopy revealed the intrabronchial masses to be blood clots and the parenchymal opacities to correspond to areas of parenchymal hemorrhage. Our cases are novel in that both bronchial and parenchymal sequelae of hemorrhage were simultaneously visualized by CT. Also, our findings suggest that bronchial blood clots should be included in the differential diagnosis of peripheral intrabronchial lesions, notably in patients presenting with hemoptysis.

Acute renal infarction. Clinical characteristics of 17 patients

We analyzed the medical records of patients with an established diagnosis of acute renal infarction to identify predictive parameters of this rare disease. Seventeen patients (8 male) who were admitted to our emergency department between May 1994 and January 1998 were diagnosed by contrast-enhanced computed tomography (CT) as having acute renal infarction (0.007% of all patients). We screened the records of the 17 patients for a history with increased risk for thromboembolism, clinical symptoms, and urine and blood laboratory results known to be associated with acute renal infarction. A history with increased risk for thromboembolism with 1 or more risk factors was found in 14 of 17 patients (82%); risk factors were atrial fibrillation (n = 11), previous embolism (n = 6), mitral stenosis (n = 6), hypertension (n = 9), and ischemic cardiac disease (n = 7). All patients reported persisting pain predominantly from the flank (n = 11), abdomen (n = 4), and lower back (n = 2). On admission, elevated serum lactate dehydrogenase was found in 16 (94%) patients, and hematuria was found in 12 (71%) of 17 patients. After 24 hours all patients showed an elevated serum lactate dehydrogenase, and 14 (82%) had a positive test for hematuria. Our findings suggest that in all patients presenting with the triad--high risk of a thromboembolic event, persisting flank/abdominal/lower back pain, elevated serum levels of lactate dehydrogenase and/or hematuria within 24 hours after pain onset--contrast-enhanced CT should be performed as soon as possible to rule out or to prove acute renal infarction.

Thoracic venous anatomy delineated by malpositioned central venous catheters on plain chest films

The aim of this essay was to demonstrate the thoracic venous anatomy as delineated by malpositioned central venous catheters on plain chest radiographs. We therefore used the didactic advantage of clinically inadvertent catheter positions. This approach was chosen to illustrate venous anatomy with plain chest radiographs, and, thereby, to recognize malpositions promptly on the modality with which positions of central venous catheters is routinely performed.

Pyrofluid inhalation in "fire-eaters": sequential findings on CT

We report the sequential computed tomography (CT) findings in two fire-eaters after accidental inhalation of pyrofluid. The initial chest radiographic findings were ambiguous and the interpretation of the radiographs was biased by clinical history unrelated to fire eating. On CT, pneumatoceles were the major findings in both patients. The pneumatoceles resolved rapidly, leaving only minimal scarring. Our cases illustrate the sequential evolution of pneumatoceles in fire-eaters after the inhalation of pyrofluid and documents the rapidity with which the lesions regress. The rare accidental inhalation of pyrofluid in fire-eaters may produce a puzzling clinical and radiographic picture and can be confused with other lung disorders.

Mycobacterium xenopi infection of a 50-year-old oil plombage complicated by bronchopleural and pleurocutaneous fistulas

We report the rare combination of simultaneous bronchopleural and pleurocutaneous fistulas 50 years after oil plombage, together with infection of both the plombage and the contralateral lung with Mycobacterium xenopi. Our case documents imaging patterns of complex fistula formation and subsequent infection resulting from oil plombage. Our case also emphasizes the infectious potential of Mycobacterium xenopi.

World Wide Web and Internet: applications for radiologists

Global exchange of information is one of the major sources of scientific progress in medicine. For management of the rapidly growing body of medical information, computers and their applications have become an indispensable scientific tool. Approximately 36 million computer users are part of a worldwide network called the Internet or "information highway" and have created a new infrastructure to promote rapid and efficient access to medical, and thus also to radiological, information. With the establishment of the World Wide Web (WWW) by a consortium of computer users who used a standardized, nonproprietary syntax termed HyperText Markup Language (HTML) for composing documents, it has become possible to provide interactive multimedia presentations to a wide audience. The extensive use of images in radiology makes education, worldwide consultation (review) and scientific presentation via the Internet a major beneficiary of this technical development. This is possible, since both information (text) as well as medical images can be transported via the Internet. Presently, the Internet offers an extensive database for radiologists. Since many radiologists and physicians have to be considered "Internet novices" and, hence, cannot yet avail themselves of the broad spectrum of the Internet, the aim of this article is to present a general introduction to the WWW/Internet and its applications for radiologists. All Internet sites mentioned in this article can be found at the following Internet address: http://www.univie.ac. at/radio/radio.html (Department of Radiology, University of Vienna)

[Staging of bronchial carcinoma]

Staging of any tumor, i.e. determination of the extent of the disease, serves to select the patients who might profit from curative surgical intervention or to define those patients with inoperable carcinomas who should be referred for other therapies, such as chemotherapy or irradiation. Furthermore, accurate staging is necessary for assessment of prognosis, for radiation therapy planning, and for differentiation of those with small-cell lung cancer or for follow-up examinations of small-cell lung cancer patients after during and after chemotherapy. The primary radiological staging and diagnostic modalities for assessment of bronchial carcinomas are computed tomography (CT) of the thorax including liver and adrenal glands, abdominal sonography, and bone scintigraphy. Magnetic resonance imaging (MRI) should be reserved for specific indications, e.g. infiltration of the chest wall or staging of patients with intolerance/allergy to intravenous contrast medium. The clinical value of nuclear medicine techniques, such as [18F]2-fluoride-2-desoxy-D-glucose positron emission tomography (FDG-PET) for evaluation of lymph nodes and distant metastases, In-111 octreotide/somatostatin receptor scans for staging of small-cell lung cancer, and thallium-201 SPECT are currently being assessed in numerous studies, although these techniques are already in routine use. In future these or nuclear medicine techniques, as well as techniques using molecular-based contrast material, especially for MR imaging, currently in experimental status, may yield serious potential for staging purposes.

Pulmonary emphysema: subjective visual grading versus objective quantification with macroscopic morphometry and thin-section CT densitometry

PURPOSE

To compare subjective visual grading of pulmonary emphysema with macroscopic morphometry and computed tomographic (CT) densitometry.

MATERIALS AND METHODS

In 62 consecutive patients who underwent thinsection CT before surgical lung resection, emphysema was objectively quantified with computer-assisted macroscopic morphometry and CT densitometry. The percentage of lung macroscopically occupied by emphysema was compared with the percentage occupied on CT scans by pixels with attenuation values lower than a predefined threshold (CT densitometry). Three readers with varying degrees of expertise subjectively graded emphysema with visual assessment at two reading sessions. Data from objective quantification and subjective grading were analyzed with correlation coefficients, and interobserver and intraobserver agreement were calculated.

RESULTS

Subjective grading of emphysema showed less agreement with the macroscopic reference standard results (r = 0.439-0.505; P < .05) than with objective CT densitometric results (r = 0.555-0.623; P < .001). The 95% CIs for the intercepts of the linear regression lines were suggestive of systematic subjective overestimation of emphysema by all three readers. Interobserver agreement was moderate (kappa = 0.431-0.589). Intraobserver agreement was good to excellent (kappa = 0.738-0.936). The expertise of individual readers did not substantially influence results.

CONCLUSION

Systematic overestimation and moderate interobserver agreement may compromise subjective visual grading of emphysema, which suggests that subjective visual grading should be supplemented with objective methods to achieve precise, reader-independent quantification of emphysema.

Subjective differentiation of normal and pathological bronchi on thin-section CT: impact of observer training

The effect of observer training on sensitivity, specificity and interobserver agreement in the differentiation between normal and pathological bronchi on computed tomography (CT) was studied. The wall thickness of bronchi with normal walls and with pathologically thickened walls were subjectively scored by three independent observers before and after a training period of 2 weeks. Sensitivity, specificity and interobserver agreement were calculated for reading sessions before and after training. Increase and decrease in agreement after training were determined. There was a statistically significant difference (p=0.001) between objectively measured wall thickness of normal and pathological bronchi, both for reference bronchi and for bronchi used for reading sessions. While training increased interobserver agreement, it had no effect on sensitivity (0.46 versus 0.44 after training) and specificity (0.71 versus 0.72 after training) in detecting pathological bronchi. Increased agreement after training was significantly (p=0.001) more frequent than decreased agreement. There is a discrepancy between the effect of training on interobserver agreement and on sensitivity and specificity in the subjective differentiation between normal and pathological bronchi. Interobserver agreement alone is not a reliable indicator of a beneficial effect of training in the evaluation of this parameter.

Mycobacteria other than tuberculosis with an emphasis on Mycobacterium xenopi in clinical specimens from AIDS patients at the University Hospital of Vienna from 1989 to 1996

This study was carried out to provide an overview of the frequency of various mycobacterial species isolated from AIDS patients at the University Hospital of Vienna from 1989 to 1996. Mycobacterium xenopi was found to be the second most common nontuberculous mycobacterial species (92 specimens from 30 patients) and was cultured predominantly from respiratory tract specimens. In 55% of patients, chest X-rays taken at the time of isolation demonstrated pathologic changes which could not be attributed to another cause. Therefore, according to our results, Mycobacterium xenopi should be viewed as an infectious agent rather than a contaminant in AIDS patients.

Radiographic findings in patients with acquired immunodeficiency syndrome, pulmonary infection, and microbiologic evidence of Mycobacterium xenopi

The authors studied radiographs and clinical histories of 29 patients with acquired immunodeficiency syndrome, symptoms of pulmonary infection, and simultaneous microbiologic evidence of Mycobacterium xenopi in the respiratory tract. The presence, nature, and distribution of radiographic abnormalities were determined and analyzed in accord with clinical information. In 26 (90%) patients, M. xenopi was the only microorganism that could be isolated. Chest radiographs were normal in 13 patients (45%) and abnormal in 16 patients (55%). Radiographic abnormalities were bilateral in 94% of cases and predominantly involved the lower lobes. Patchy peribronchial opacities (44%) and miliary nodules (24%) were the most common abnormalities. Reticular opacities and parenchymal consolidation were seen in 12% of patients. Pleural effusion was seen in 18% of patients. No patients had cavitations or adenopathy. There was no statistically significant difference regarding the mean age (38.7+/-7.3 years vs. 40.2+/-11.0 years), the duration of clinically evident human immunodeficiency virus infection (2.7+/-1.2 years vs. 2.8+/-1.4 years), and the mean of CD4 cell counts (50.6+/-15.3 cells/ml vs. 47.4+/-15.9 cells/ml) between the patients with and without abnormalities on chest radiographs. In patients with acquired immunodeficiency syndrome, pulmonary infection, and simultaneous microbiologic evidence of M. xenopi, chest radiographs can be normal in a substantial number of cases. When radiographic abnormalities are present, they differ from those seen in patient not infected with the human immunodeficiency virus who had pulmonary infection caused by M. xenopi and from patients with acquired immunodeficiency syndrome and pulmonary infection with nontuberculous mycobacteria other than M. xenopi. Although these findings are not specific, they may be of importance in the imaging of patients with acquired immunodeficiency syndrome, notably in areas where M. xenopi is endemic.

Double inversion recovery imaging of the brain: initial experience and comparison with fluid attenuated inversion recovery imaging

The purpose of this study was to evaluate the diagnostic efficacy of the double inversion recovery fast spin echo (DIR-FSE) sequence for brain imaging compared to the fluid-attenuated inversion recovery (FLAIR) sequence. DIR-FSE and FLAIR-FSE sequences were obtained and compared side by side. Image assessment criteria included lesion conspicuity, contrast between different types of normal tissue, image quality, and artifacts. In addition, contrast ratios and contrast-to-noise ratios were determined. Scan time of DIR-FSE was 33% longer than scan time of FLAIR-FSE. Overall lesion conspicuity was equal on DIR-FSE and FLAIR-FSE; however, DIR-FSE showed particular advantages for infratentorial lesions and lesions with only poor contrast on T2-weighted images, whereas FLAIR was slightly superior for small superficial cerebral abnormalities. Gray-white differentiation was better with DIR-FSE. Cerebrospinal fluid suppression was equal on both sequences; cerebrospinal fluid pulsation artifacts were more pronounced on DIR-FSE but did not cause diagnostic difficulties on these images. We conclude that DIR-FSE might be obtained if infratentorial lesions and abnormalities with only slightly prolonged T2 relaxation times are suspected. Otherwise, FLAIR-FSE seems preferable.

Severity assessment of acute pulmonary embolism with spiral CT: evaluation of two modified angiographic scores and comparison with clinical data

Spiral computed tomography (CT) has shown promising results in the detection of acute pulmonary embolism. The aim of this study was to investigate whether the severity of acute pulmonary embolism could be quantitatively assessed with spiral CT examinations and to test the potential clinical impact of this information. In a consecutive series of 123 patients screened with spiral CT for suspected acute pulmonary embolism, 31 patients (25%) had evidence of emboli. The severity of pulmonary arterial obstruction in those 31 spiral CT examinations was evaluated by two independent observers using angiographic scores previously described by Walsh (29) and Miller (30), adapted to the needs of spiral CT. Clinical patient subgroups were defined according to oxygen saturation, heart rate, and echocardiographic signs of right ventricular strain. CT severity scores were then correlated to each other and to clinical parameters using the Spearman rank test. Interobserver agreement was calculated using the analysis of variance. Both modified Walsh and Miller scores were readily reproducible and showed interobserver agreements of 0.85 and 0.96, respectively (p = 0.001). Patients with mild and marked clinical abnormalities showed statistically significant differences between CT severity scores. Differences between severity scores of patients with moderate and marked clinical abnormalities were somewhat significant. No significant mean severity score differences were seen between patients with mild and moderate clinical abnormalities. Although correlations of severity scores and detailed clinical parameters within the defined subgroups were moderate to poor, threshold scores greater than 10 (Miller) and greater than 11 (Walsh) always indicated marked clinical abnormalities. The modified scores presented in this study constitute a readily reproducible method for the quantitative assessment of acute pulmonary embolism severity on spiral CT examinations.

Radiographic detection of intrabronchial malpositions of nasogastric tubes and subsequent complications in intensive care unit patients

OBJECTIVE

The aim of our study was to illustrate the radiographic spectrum of the intrabronchial malposition of nasogastric tubes and subsequent complications, and to discuss the role of radiography in the detection of such malpositions.

DESIGN

Retrospective clinical investigation.

SETTING

Tertiary care university teaching hospital.

PATIENTS AND METHODS

We reviewed chest radiographs of 14 intensive care patients with nasogastric tubes malpositioned in the tracheobronchial tree. The site and anatomic location of the malposition were recorded. Complications due to tube malpositioning were monitored on follow-up radiographs and on computed tomographic examinations, which were available in 4 patients.

RESULTS

Nine of 14 nasogastric tubes were inserted in the right and 5 in the left tracheobronchial tree. Tube tips were malpositioned in the lower lobe bronchi (50%), the intermediate bronchus (36%), and the main bronchi (14%). There was perforation of the bronchial system with subsequent pneumothorax in 4 patients. In 4 other patients, pneumonia developed at the former site of the malpositioned tube tip. Radiographic detection of nasogastric tube malpositioning was prompt in 9 patients and delayed in 5 patients.

CONCLUSIONS

Whereas clinical signs of nasogastric tube malpositioning in intensive care patients may be absent or misleading, chest radiography can accurately detect nasogastric tube malpositions in the tracheobronchial tree, may prevent complications, and avoid the use of further costly or invasive diagnostic techniques.

[Diagnostic imaging within the scope of lung transplantation]

PURPOSE

Recent progress in both surgical techniques and therapeutic medication of immunosupression have made lung transplantation a promising option for patients with untreatable diseases of the lung parenchyma. Because preoperatively and postoperatively diagnostic imaging has crucial importance for patient management and clinical decision making we aim to describe imaging features of frequent pathologies in patients after lung transplantation.

MATERIALS AND METHODS

We reviewed radiological examinations of patients after lung transplantation performed at our institution over a period of four years, and exemplary cases were selected for presentation. Our interest was focussed on both conventional and CT-imaging of postoperative alterations, infections, organ rejection, and pathologies of the airways. Moreover, post-biopsy alterations and lymphoproliferative disorders were documented. Together with clinical information we aimed to give a concise description of specific pathologic entities. Also, the diagnostic impact of more recent techniques such as spiral-CT and thin-section CT should be discussed.

RESULTS

In cases of early postoperative pathologies and in infections conventional radiography is diagnostically reliable when interpreted together with clinical information. In cases of acute or chronic organ rejection, of lymphoproliferative disorders, of diseases of central or small airways, and for the choice of an appropriate biopsy site, CT has proved to be a valuable imaging modality. Spiral-CT allows airway volumetry in cases of strictures or dehiscence, thin-section CT enables assessment of subtle parenchymal pathologies, notably in cases of chronic organ rejection.

DISCUSSION

The radiographic findings described below represent specific pathogenetic entities in lung-transplant patients (postoperative alterations, infections, posttransplant lymphoproliferative disorders). Their accurate recognition will have a positive impact on the further clinical history. In the near future, more sophisticated CT techniques should widen our pathogenetic knowledge of alterations in transplanted lungs.

Azygos arch cannulation by central venous catheters: radiographic detection of malposition and subsequent complications

The aim of this study was to determine the frequency of radiographically evident central venous catheter misplacement in the azygos arch and to analyze whether the frequency of azygos arch cannulation is dependent on the anatomical site of catheter insertion. We reviewed 1,287 postprocedural examinations and 3,441 follow-up examinations. Catheters had been inserted through the left (6%) or right (15%) internal jugular veins and through the left (32%) or right (46%) subclavin veins. Radiographs were analyzed for possible catheter malposition in the azygos arch and for complications related to this malposition. Catheter malposition in the azygos arch was seen on 16/1,287 (1.2%) postprocedural radiographic examinations. Of the 16 malpositioned catheters, 11 (69%) had been inserted in the left subclavian vein, three (19%) in the left jugular vein, two (12%) in the right subclavian vein, and none (0%) in the right jugular vein. There was a statistically significant difference in the frequency of azygos arch cannulation between left- and right-sided catheters (p = 0.001). All complications consisted of venous perforations and were seen in three of 16 cases (19%). Azygos arch cannulation is a rare but hazardous central venous catheter malposition that occurs early after catheter insertion and carries a substantial risk for complication. The risk for azygos arch cannulation is substantially increased if catheters are inserted in left-sided veins. Because of the severity of subsequent complications, radiologists should be vigilant in the detection of this rare malposition.

Lung metastases

The lungs are among the most prominent target organs for metastatic disease. Most frequently, lung metastases originate from cancers of the head and neck, breast, stomach, pancreas, kidney, bladder, the male and female genitourinary tract, and sarcomas. Plain chest radiography is typically the modality used for detection and therapeutic monitoring; however, the use of CT for these purposes is becoming more frequent. Currently, spiral CT appears to be the most sensitive imaging technique in the identification of metastases, because it detects a higher number of pulmonary nodules compared to other techniques. Pulmonary metastatic disease manifests itself by the presence of pulmonary nodules, lymphangitic carcinomatosis, endobronchial tumors, and pleural involvement. Nevertheless, the differential diagnosis is an important consideration, particularly in patients with solitary pulmonary nodules, systemic disorders, and signs or symptoms indicative of infection. The role of the radiologist involves the identification of metastatic disease, monitoring of response to therapy, and the use of invasive procedures when the differential diagnosis indicates the need for biopsy and histopathologic proof. The radiologist must be aware of the impact of his diagnosis on patient management and should be familiar with oncologic strategies as well as the terminology used to characterize tumor response. In future, the role of imaging may further expand due to the increased sensitivity in lesion detection, increased specificity in lesion (tissue) characterization using MR imaging imaging, and reduced radiation exposure.

[Pleural and pulmonary changes within the scope of rheumatoid arthritis]

Pulmonary complications caused by rheumatoid arthritis are a clinically relevant aspect of this chronic arthropathy. Those complications can involve all parts of the thorax, including the lung parenchyma, the pleura, and the thoracic cage. The most common complications are necrobiotic nodules, pleural abnormalities, Caplan's syndrome, parenchymal fibrosis, bronchiolitis obliterans, and iatrogenic damage of lung the parenchyma. This article reviews pulmonary abnormalities induced by rheumatoid arthritis and their clinical and radiological findings. In addition, the role of different imaging modalities in the diagnostic work-up of pulmonary complications caused by rheumatoid arthritis is discussed.

[Computerized tomography of AIDS associated thoracic diseases]

Pulmonary infections and tumors are a major cause of death in patients with AIDS. The combination of clinical, radiological, laboratory, and pathohistological data helps to narrow the spectrum of differential diagnoses or even allows a specific diagnosis in many patients. Nevertheless, an accurate diagnosis should be obtained as soon as possible during the clinical course of the illness to initiate treatment in time. Computed tomography (CT) has proven to provide promising results in the diagnosis of AIDS-related thoracic diseases. The aim of this paper was to demonstrate the diagnostic capacities of CT in the context of particular AIDS-related thoracic pathologies. Additional information on the spectrum of pathological agents and on differential diagnostic signs is summarized.

Weil disease: importance of imaging findings for early diagnosis

Weil disease is a rare and severe outcome of infection with leptospires. We report the radiographic appearance of this disease in a patient with hepatic, renal, and pulmonary involvement. Imaging findings added significantly to an early correct diagnosis and, thus, to immediate and successful therapy in this critically ill patient.

[Spiral-CT [corrected] in chronic lung thromboembolism

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare result of recurrent pulmonary embolism and is treated by pulmonary thromboendarterectomy. Knowledge of the exact location of the thrombi is necessary in planning this operation. To date, pulmonary, angiography is the diagnostic imaging gold standard. Since the introduction of spiral CT excellent vascular opacification of the pulmonary arteries has become feasible, and thrombi in the pulmonary arteries can be visualized directly. Spiral CT is superior to angiography in demonstrating thrombi in the central pulmonary arteries, whereas angiography proves superior to CT in the evaluation of abnormalities within segmental arteries. The sensitivity of spiral CT in confirming the diagnosis of CTEPH is reported to be more than 90%. According to the literature and based on our own results, the decision concerning operability is possible on the basis of spiral CT images in more than 80% of patients with CTEPH. Spiral CT as a non-invasive tool may be used for CTEPH screening, for postoperative follow-up after pulmonary thrombendarterectomy and, combined with pulmonary angiography, to optimize operation planning.

Bronchial wall thickness: appropriate window settings for thin-section CT and radiologic-anatomic correlation

PURPOSE

To analyze the influence of computed tomographic (CT) window settings on bronchial wall thickness and to define appropriate window settings for its evaluation.

MATERIALS AND METHODS

Three inflation-fixed lungs were scanned with a section thickness of 1.5 mm by using a high-spatial-frequency algorithm. Wall thickness in 10 bronchial specimens was measured with planimetry. Window centers were altered in a range of -200 to -900 HU and window widths in a range of 400-1,500 HU. Relative and absolute differences between CT and planimetric values were calculated. CT and planimetric measures were correlated. Inter- and intraobserver variabilities were determined.

RESULTS

Window widths less than 1,000 HU resulted in a substantial overestimation of bronchial wall thickness, whereas widths greater than 1,400 HU resulted in an underestimation of bronchial wall thickness. There was no interaction between "width" and "center" regarding their influence on bronchial walls (F = 0.23; P = .99). Correlation between CT and planimetry was statistically significant (r = .85; P = .0001). Differences between the two observers were not statistically significant; results of the measurements of the two observers correlated well (r = .97; P = .001).

CONCLUSION

Bronchial wall thickness on thin-section CT scans should be evaluated with window centers between -250 and -700 HU and with window widths greater than 1,000 HU. Other than window settings, notably window widths less than 1,000 HU, can lead to substantial artificial thickening of bronchial walls.

[Spiral CT in acute pulmonary embolism]

Pulmonary embolism is a frequent and potentially life-threatening event with uncharacteristic clinical manifestations. Diagnosis is commonly established by ventilation/perfusion scintigraphy and pulmonary angiography. Both methods, however, carry substantial drawbacks. Therefore, clinicians claim that there is a need for an accurate and non-invasive diagnostic modality. Spiral CT of the pulmonary arteries is a recent modality, that allows reliable visualization of emboli in pulmonary arteries up to fourth-order branches. This paper reviews the technical aspects, typical findings and diagnostic pitfalls of this recent technique. The potential role of spiral CT in the screening of patients with suspected pulmonary embolism is discussed and selected cases are presented.

Three-dimensional spiral CT cholangiography in patients with suspected obstructive biliary disease: comparison with endoscopic retrograde cholangiography

PURPOSE

To evaluate the diagnostic potential of spiral computed tomography (CT) performed after the administration of cholangiographic contrast material (spiral CT cholangiography) in patients with suspected obstructive biliary disease.

MATERIALS AND METHODS

After infusion of meglumine iodoxamate, 29 patients underwent upper abdominal spiral CT with subsequent three-dimensional rendering of the biliary tract. In 27 patients, the presence, site, and extent of biliary obstruction were compared with that at endoscopic retrograde cholangiography (ERC).

RESULTS

Spiral CT cholangiography correctly depicted biliary obstruction in 14 of 27 patients, with no false-positive or false-negative cases. In one patient, the precise length of a common bile duct stenosis could not be assessed with spiral CT cholangiography. ERC demonstrated intrahepatic ductal stenoses more clearly in two patients. In two patients with hilar cholangiocarcinomas, spiral CT cholangiography depicted undrained areas not seen with ERC.

CONCLUSION

Spiral CT cholangiography allows accurate assessment of the biliary system in patients with suspected obstructive biliary disease.