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Query: UMLS:C0034065 (pulmonary embolism)
 14,979 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent years have witnessed an explosion in imaging technology applicable to chest medicine. These include CT and magnetic resonance angiography (MRA) for the diagnosis of pulmonary embolism, and high-resolution CT for the detection and characterization of diffuse lung diseases and the quantification of emphysema. Newly developed approaches to pulmonary functional imaging using CT and MRI have been applied to the evaluation of pulmonary ventilation and perfusion and to the detection of small airways disease. Volumetric CT imaging techniques together with advanced image processing have made possible "virtual bronchoscopy." Positron emission tomography provides an important new approach to the accurate detection and staging of chest malignancies and to the evaluation of pulmonary nodules. Finally, new digital imaging techniques, which are rapidly replacing conventional x-ray film, offer the possibility of computer-aided diagnosis.
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PMID:Recent advances in pulmonary imaging. 1055 4

MRI is a valuable method for evaluating thoracic vascular lesions by virtue of its non-invasiveness and multiplanar capability. In addition, ionizing radiation and iodinated contrast medium are not required. Electrocardiographically gated T1 weighted spin echo MRI remains the principal technique for demonstrating the anatomy and morphology of thoracic vascular diseases. Cine MRI allows dynamic evaluation of vascular flow, whereas MR angiography is particularly useful in the two-dimensional (2D) or three-dimensional (3D) display of vascular anatomy. This pictorial review illustrates the use of 2D time-of-flight MR angiography in the assessment of various thoracic vascular conditions including aortic arch and great vessel anomalies, heterotaxic syndromes, aortic dissection, aortic or arch vessel aneurysms, pulmonary embolism, pulmonary sequestration, axillofemoral bypass and tumour/vessel relationships.
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PMID:MRI of thoracic vascular lesions with emphasis on two-dimensional time-of-flight MR angiography. 1056 Mar 47

The feasibility of qualitative assessment of pulmonary perfusion using dynamic contrast enhanced MRI with ultra-short TE has recently been demonstrated. In the current study, quantitative analysis was attempted based on the indicator dilution principle using a pig model of pulmonary embolism. The results were compared with the absolute pulmonary perfusion obtained with colored microspheres. The inverse of apparent mean transit time (1/tau(app)), distribution volume (V), and V/tau(app) were correlated well with the absolute lung perfusion. This study demonstrates that MR has the potential to evaluate pulmonary perfusion quantitatively. Magn Reson Med 42:1033-1038, 1999.
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PMID:Quantitative assessment of pulmonary perfusion with dynamic contrast-enhanced MRI. 1057 24

Objective: To determine the incidence, timing, and associated clinical characteristics of objectively diagnosed pregnancy-associated venous thromboembolism (VTE).Methods: A retrospective review of VTE cases occurring between 1978 and 1996 was performed. Cases of deep venous thrombosis (DVT) and pulmonary embolism (PE) were identified by ICD-9 discharge diagnosis code and review of antepartum and coagulation laboratory databases. Study inclusion criteria required the objective diagnosis of VTE with either Doppler ultrasound, impedance plethysmography, pulmonary angiography, ventilation-perfusion scanning, or CT/MRI.Results: Among 268,525 deliveries there were 165 (0.06%) episodes of VTE (1/1627 births). There were 127 cases of DVT and 38 cases of PE. Only 14% (23/165) had a prior history of DVT or PE. Most DVTs occurred in the left leg (104/127, 81.9%). Nearly three quarters of the DVTs (95/127, 74.8%) occurred in the antepartum period. Among the antepartum DVT cases, half were detected prior to 15 weeks of gestation (47/95, 49.5%), with only 28 cases occurring after 20 weeks (P <.0001). The majority of the PEs occurred in the postpartum period (23/38, 60.5%). There were only 3 maternal deaths due to PE, all associated with cesarean section. Only 1 patient developed PE while on heparin therapy for DVT while 11 others had complications attributable to heparin use.Conclusion: Most pregnancy-related VTE occurs in the antepartum period. The risk of deep venous thrombosis appears to begin early in pregnancy, even before the second trimester. The highest risk period for pulmonary embolism is after cesarean delivery. Maternal complications of heparin anticoagulation during pregnancy are rare.
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PMID:Incidence, clinical characteristics, and timing of objectively diagnosed venous thromboembolism during pregnancy. 1083 89

In recent years, a number of modalities have been evaluated for the diagnosis of venous thromboembolism. The role of these modalities is still evolving. While ventilation-perfusion scanning is important in the diagnosis of venous thromboembolism, spiral CT scanning, MRI, and D-dimer assays are now being used more often, either exclusively or in combination with ventilation-perfusion scanning. A number of diagnostic algorithms using these modalities are currently being evaluated. Regardless of which diagnostic approach is used, the clinician must be aware of some key limitations. Spiral CT scanning has gained popularity because it is noninvasive and can rapidly identify other cardiopulmonary diseases that mimic pulmonary embolism. Its use has been limited because of its inability to detect subsegmental pulmonary emboli. D-dimer assays offer promise as rapid, inexpensive screening tools. However, the wide variability in assay performance has limited its usefulness. We recommend that if D-dimer assays are to be used in a diagnostic algorithm, the clinician be aware of the details of the assay. At present, lack of data precludes use of MRI as a primary diagnostic tool for detection of venous thromboembolism.
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PMID:Improving detection of venous thromboembolism. New technology holds promise for early, precise diagnosis. 1102 Dec 57

Idiopathic granulomatous inflammation of the pituitary gland occurs rarely, and is usually identified as an incidental finding at autopsy. However, it may present during life as a mass lesion that clinically mimics other more common pituitary gland lesions. We report a 54-year-old woman presenting with acute onset diabetes insipidus whose MRI showed a 1.1 cm pituitary mass, with infundibular thickening and meningeal enhancement. Biopsy demonstrated granulomatous hypophysitis with multinucleate histiocytes. Special studies for infectious organisms were negative. The patient's disease progressed following biopsy, causing complete loss of vision in the right eye. This responded to high-dose steroids and local lowdose radiation. She later developed an acute inferior myocardial infarction. Laboratory tests failed to demonstrate an underlying autoimmune process. While recovering from this myocardial infarction, she succumbed to pulmonary embolism. Autopsy revealed moderate residual chronic infundibular inflammation. No evidence of systemic or residual pituitary granulomatous disease was identified. To the best of our knowledge, this is the first case of idiopathic granulomatous hypophysitis initially diagnosed by biopsy to have post-mortem neuropathologic examination.
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PMID:Idiopathic giant-cell granulomatous hypophysitis. Report of a case with autopsy follow-up. 1112 23

Although 3D MRA has been shown to provide excellent depiction of the pulmonary arterial tree, its clinical use has been limited due to lengthy breath-holding requirements. Employing the newest gradient generation (1.5 T MR system, amplitude of 40 mT/m and a slew rate of 200 mT/m/msec), we evaluated a technique permitting the dynamic acquisition of 3D data sets of the entire pulmonary tree in under 4 seconds. Coronal image sets were collected using a repetition time of 1.64 msec and an echo time of 0.6 msec, resulting in an acquisition time of 3.74 seconds. Three volunteers and eight dyspneic patients with known or suspected pulmonary embolism underwent MRI of the pulmonary arteries. The pulmonary arterial tree was visible to a subsegmental level in all examined subjects. Regarding the presence of pulmonary emboli in four patients, there was complete concordance between MR angiographic findings and those of corroborative studies. We conclude that diagnostic MRA of the pulmonary vasculature can be obtained even in patients with severe respiratory distress.
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PMID:Dynamic 3D MR angiography of the pulmonary arteries in under four seconds. 1124 9

Magnetic resonance imaging using the MR signal from hyperpolarized noble gases 129Xe and 3He may become an important new diagnostic technique. Alex Pines (adapting the hyperpolarization technique pioneered by William Happer) presented MR spectroscopy studies using hyperpolarized 129Xe. The current authors recognized that the enormous enhancement in the delectability of 129Xe, promised by hyperpolarization, would solve the daunting SNR problems impeding their attempts to use 129Xe as an in vivo MR probe, especially in order to study the action of general anesthetics. It was hoped that hyperpolarized 129Xe MRI would yield resolutions equivalent to that achievable with conventional 1H2O MRI, and that xenon's solubility in lipids would facilitate investigations of lipid-rich tissues that had as yet been hard to image. The publication of hyperpolarized 129Xe images of excised mouse lungs heralded the emergence of hyperpolarized noble-gas MRI. Using hyperpolarized 3He, researchers have obtained images of the lung gas space of guinea pigs and of humans. Lung gas images from patients with pulmonary disease have recently been reported. 3He is easier to hyperpolarize than 129Xe, and it yields a stronger MR signal, but its extremely low solubility in blood precludes its use for the imaging of tissue. Xenon, however, readily dissolves in blood, and the T1, of dissolved 129Xe is long enough for sufficient polarization to be carried by the circulation to distal tissues. Hyperpolarized 129Xe dissolved-phase tissue spectra from the thorax and head of rodents and humans have been obtained, as have chemical shift 129 Xe images from the head of rats. Lung gas 129Xe images of rodents, and more recently of humans, have been reported. Hyperpolarized 129Xe MRI (HypX-MRI) may elucidate the link between the structure of the lung and its function. The technique may also be useful in identifying ventilation-perfusion mismatch in patients with pulmonary embolism, in staging and tracking the success of therapeutic approaches in patients with chronic obstructive airway diseases, and in identifying candidates for lung transplantation or reduction surgery. The high lipophilicity of xenon may allow MR investigations of the integrity and function of excitable lipid membranes. Eventually, HypX-MRI may permit better imaging of the lipid-rich structures of the brain. Cortical brain function is one perfusion-dependent phenomena that may be explored with hyperpolarized 129Xe MR. This leads to the exciting possibility of conducting hyperpolarized 129Xe functional MRI (HypX-fMRI) studies.
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PMID:Development of hyperpolarized noble gas MRI. 1154 65

The authors report a case of successful detection of pulmonary embolism using gadolinium-enhanced spiral CT (Gadodiamide, 0.4 mmol/kg, 2 ml/s, delay 18 s) in a 77-year-old woman, with previous allergy to iodinated contrast medium, and renal failure, who presented with pulmonary arterial hypertension. Doppler ultrasound of the lower limbs was first performed and revealed a deep venous thrombosis of the right lower limb. To establish if venous thrombosis was the cause of pulmonary hypertension and to confirm that pulmonary endarterectomy was not indicated in this situation, several imaging modalities were performed. Lung scintigraphy and MRI were non-diagnostic. Gadolinium-enhanced spiral CT demonstrated a large thrombus located proximally and in a segmental artery of the right lower lobe. This case illustrates the potential usefulness of gadolinium as alternative contrast agent with spiral CT to diagnose pulmonary embolism and elucidate the cause of pulmonary arterial hypertension in a patient with some contraindications for iodinated contrast medium injection.
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PMID:Demonstration of pulmonary embolism with gadolinium-enhanced spiral CT. 1170 76

Conventional nuclear ventilation/perfusion (V/Q) scanning is limited in spatial resolution and requires exposure to radioactivity. The acquisition of pulmonary V/Q images using MRI overcomes these difficulties. When inhaled, hyperpolarized helium-3 ((3)He) permits MRI of gas distribution. Magnetic labeling of blood (arterial spin-tagging (AST)) provides images of pulmonary perfusion. Three normal subjects, two patients who had undergone single lung transplantation for emphysema, and one subject with pulmonary embolism (PE), were imaged. (3)He distribution and blood perfusion appeared uniform in the normal subjects and throughout the lung allografts. Gas distribution and perfusion in the emphysematous lungs were non-uniform and paralleled radiographic abnormalities. AST imaging alone revealed a lower-lobe wedge-shaped perfusion defect in the patient with PE that corresponded to computed tomography (CT) imaging. Hyperpolarized (3)He gas is demonstrated to provide ventilation images of the lung. Blood perfusion information may be obtained during the same examination using the AST technique. The sequential application of these imaging methods provides a novel tool for studying V/Q relationships.
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PMID:Pulmonary ventilation and perfusion scanning using hyperpolarized helium-3 MRI and arterial spin tagging in healthy normal subjects and in pulmonary embolism and orthotopic lung transplant patients. 1211 53


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