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 and O2-enhanced MRT of the diseased lung. Emphysema, fibrosis, mucoviscidosis]. / T1-Maps und O2-verstärkte MRT der erkrankten Lunge. Emphysem, Fibrose, Mukoviszidose.

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.

UNLABELLED: 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.

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.

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.

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.