Computed tomography assessment of ground-glass opacity: semiology and significance.

Among the computed tomography (CT) signs of parenchymal lung disease, the ground-glass pattern is the one most difficult to diagnose and most influenced by CT technique. Ground-glass opacity may result from changes in the airspaces or interstitial tissues in acute or chronic infiltrative lung disease. It may also be seen as a consequence of increased capillary blood volume in redistribution of blood flow due to airway disease, emphysema, or pulmonary thromboembolism. Definition of this sign on high-resolution CT (HRCT) images, its various HRCT patterns, and potential pitfalls in its recognition are described with special attention to optimal HRCT technique.

[Helical x-ray computed tomography of renal arteries. Apropos of 300 patients]. / Angioscanographie hélicoïdale des artères rénales. A propos de 300 patients.

PURPOSE: To evaluate the role of helical CT angiography (CTA) in the detection of renal artery stenosis in hypertensive patients. MATERIALS AND METHODS: We studied 300 hypertensive patients (50 prospectively and 250 consecutively) with CTA and arteriography (n = 118). Helical acquisition (collimation 3 mm; pitch = 1, 20 seconds acquisition time) was performed 20-45 seconds after contrast injection (300 mgl/ml; 120 ml, 4 ml/sec). Transverse axial views and 3D reconstructions were analyzed (360 degrees interpolation algorithm, 1 mm overlapped). RESULTS: In the prospective series, CTA sensitivity was 100% for main renal artery stenoses and specificity was 98.2%; however 7/32 renal accessory arteries were not visualized. In the 300 patients studied, seventy-four stenoses were detected. There were 5 false-positive and 5 false-negative studies. Secondary hypertension was detected in 26% of patients (including 14 cases of adrenal hyperplasia). CONCLUSION: CTA is a promising technique for the detection of renal artery stenosis in hypertensive patients.

Pulmonary arteriovenous malformations: evaluation with CT of the chest before and after treatment.

A total of 109 single or multiple pulmonary arteriovenous malformations (PAVMs) were evaluated with computed tomography (CT) of the chest in 40 patients separated into three groups to study the usefulness of CT (a) in the diagnosis and pretherapeutic management of PAVMs by comparison with selective pulmonary angiography of each lung (group 1: 20 patients), (b) in the follow-up of patients who received treatment (group 2: 27 patients), and (c) as an isolated diagnostic procedure in elderly patients (n = 3) or family members with Osler-Weber-Rendu disease (n = 8) (group 3: 11 patients). Follow-up ranged from several weeks to 10 years (mean follow-up, 4 years). In group 1, conventional and dynamic CT enabled identification of 107 PAVMs (98.2%) (vs 65 PAVMs [59.6%] identified with angiography), with confident segmental location in 56 of 65 PAVMs (86%) and reliable analysis of angioarchitecture in 17 PAVMs (26%) (vs 39 PAVMs [60%] analyzed with angiography). In group 2, progressive aneurysmal retraction was associated with successful occlusion. In group 3, CT enabled noninvasive evaluation of patients unable to undergo treatment and detection of PAVMS in family members.

Transcatheter occlusion of pulmonary arterial circulation and collateral supply: failures, incidents, and complications.

Failures and complications were analyzed retrospectively in 45 patients treated with embolotherapy or occlusion of pulmonary arterial circulation. Pulmonary arterial branches were occluded with steel coils in 19 patients with pulmonary arteriovenous malformations, 17 with hemoptysis of pulmonary artery (PA) origin, and one with massive parenchymal shunt. Bronchial arterial supply to the lung was embolized with small particles in eight cases of hemoptysis and systemic to pulmonary arterial antegrade shunt secondary to chronic thromboembolism. Asymptomatic incidents included catheterization failures, vascular damage, partial occlusion, partial recanalization of the thrombus, ectopic deposition of a coil, and delayed bacterial contamination of the thrombus. A few cases of transient clinical and radiologic signs of pulmonary infarction were observed after complete occlusion of the PA and bronchial artery embolization. This complication was never observed after complete occlusion of main right or left PA, inferior right or left PA, or segmental branches. The management and prevention of these complications, the role of bronchial arterial collateral pathways, and the importance of the site of PA occlusion in the development of pulmonary infarction are discussed.

Central pulmonary thromboembolism: diagnosis with spiral volumetric CT with the single-breath-hold technique--comparison with pulmonary angiography.

Forty-two patients were prospectively evaluated with spiral volumetric computed tomography (CT) and selective pulmonary angiography of each lung to detect central pulmonary thromboembolism. Spiral volumetric CT images obtained with either 90 mL of 30% contrast material or 120 mL of 12% contrast material were graded as excellent or good in 98% of the examinations (41 patients). Diagnosis of pulmonary embolism with spiral volumetric CT was based on the direct visualization of intraluminal clots: partial filling defects (n = 41; 37%), complete filling defects (n = 51; 46%), "railway track" signs (n = 6; 5%), and mural defects (n = 14; 12%). All 23 patients with normal findings of spiral volumetric CT had normal findings of pulmonary angiography. With spiral volumetric CT, the finding of 112 central emboli (eight main, 28 lobar, and 76 segmental) corresponded exactly to the angiographic findings, but nine intersegmental lymph nodes were erroneously interpreted as filling defects. In one case of normal pulmonary angiographic findings, asymmetry in pulmonary arterial perfusion was misinterpreted as pulmonary embolism with spiral volumetric CT. Spiral volumetric CT can reliably depict thromboemboli in second- to fourth-division pulmonary vessels.

Angioarchitecture of pulmonary arteriovenous malformations: clinical utility of three-dimensional helical CT.

PURPOSE: To determine the clinical utility of three-dimensional (3D) helical computed tomography (CT) in pretherapy evaluation of the angioarchitecture of pulmonary arteriovenous malformations (PAVMs). MATERIALS AND METHODS: Thirty-seven PAVMs were prospectively evaluated with both helical CT and pulmonary angiography. Single-threshold shaded-surface displays were obtained with 2- or 5-mm section thickness, a pitch of 1, and a 360 degrees linear interpolation algorithm but without injection of contrast medium. RESULTS: A reliable analysis of the angioarchitecture of 28 PAVMs (76%)--25 simple and three complex--was provided by 3D reconstructions; combined interpretation of 3D images and transverse sections led to accurate evaluation of 35 PAVMs (95%). Positioning of the target anatomy in the reconstructed volume, threshold value, number of stacked sections, and section thickness influenced the diagnostic information. CONCLUSION: Unenhanced 3D helical CT appears to be a reliable noninvasive tool for pretherapy evaluation of PAVMs.

Popliteal vascular disease: evaluation with spiral CT angiography.

PURPOSE: To evaluate the potential role of spiral computed tomographic (CT) angiography in the diagnosis of popliteal artery disease. MATERIALS AND METHODS: In 26 consecutive patients referred for popliteal arteriography, the authors performed additional spiral CT angiography with the following protocol: 3-5-mm collimation, 4-6 mm/sec table speed, and 2-3-mm overlap during 32 seconds, with use of 110 mL of contrast medium. Axial transverse sections and shaded surface display and multiplanar reformation reconstruction images were analyzed. All patients underwent previous Doppler ultrasound examination. RESULTS: In the 52 arteries imaged, arteriography showed 14 isolated hemodynamically significant (>50% diameter reduction) stenoses (due to popliteal artery entrapment in one case), four occluded arteries, and 11 aneurysms. CT angiography also demonstrated these 14 stenoses and four occlusions. However, axial transverse views at CT angiography showed that eight of the stenoses were associated with other abnormalities (aneurysm in six, popliteal artery entrapment syndrome in one, and cystic adventitial disease in one) and that two of the occlusions resulted from popliteal artery entrapment syndrome (n = 1) and thrombosis of an aneurysm (n = 1). CT angiography also demonstrated the 11 aneurysms shown with arteriography. CONCLUSION: Popliteal artery lesions can be diagnosed with spiral CT angiography, which provides detailed information on the wall and diameter of the artery and relation of the artery to adjacent structures.

Helical CT angiography compared with arteriography in the detection of renal artery stenosis.

OBJECTIVE: The aim of the study was to improve the accuracy and detection rate for renal vascular lesions on helical CT angiography with an improved acquisition protocol and postprocessing. SUBJECTS AND METHODS: Fifty hypertensive patients (man age, 53 years old) referred because of clinical suspicion on renal artery stenosis were prospectively studied with digital renal arteriography and helical CT angiography. A 20-sec helical scan (collimation, 3 mm; pitch, 1) was obtained after injection of contrast medium. Interpretation was base on transverse sections, shaded-surface-display and maximum-intensity-projection reconstructions, and two-dimensional multiplanar reconstruction cuts obtained from shaded-surface-display reconstructions. RESULTS: Arteriography visualized 131 renal arteries (including 32 accessory arteries). Sixteen had significant (greater than 50% in diameter) stenosis. On helical CT angiography, 14 of these 16 stenoses were detected; two were missed (false-negatives), and two additional stenoses (false-positives) were reported. Sensitivity and specificity were 88% and 98%, respectively. Considering only main renal arteries, the sensitivity and the specificity of helical CT angiography were 100% and 98%, respectively. Helical CT angiography detected Conn's syndrome, which was responsible for hypertension, in two other patients. CONCLUSION: The accuracy and detection rate for renal artery stenosis on helical CT angiography compared with arteriography is improved with the described protocol.

Pulmonary sarcoidosis: role of CT in the evaluation of disease activity and functional impairment and in prognosis assessment.

PURPOSE: To investigate the role of computed tomography (CT) in determining disease activity and functional impairment and in predicting the prognosis of lung involvement in patients with sarcoidosis. MATERIALS AND METHODS: Two groups of patients underwent CT, pulmonary function tests, and bronchoalveolar lavage. Disease activity was based on serum angiotensin converting enzyme activity and/or lymphocytosis at bronchoalveolar lavage. CT findings in group 1 were correlated with indexes of disease activity and functional parameters at diagnosis. In group 2, evaluation initially and at follow-up led to investigation of correlations between initial CT findings and evolution of disease activity and functional impairment. RESULTS: CT abnormalities in group 1 were nodules, air-space consolidation, lung distortion, septal and nonseptal linear areas of high attenuation, ground-glass attenuation, and honeycombing. Profusion of septal lines was the only CT finding that correlated with disease activity. Statistically significant (P < .05) but low correlation (r < .48) was observed between the extent of abnormalities at CT and impairment of lung function, except for nodules. CONCLUSION: Profusion of lung changes reflects functional impairment but not disease activity. CT findings cannot help predict the evolution of lung changes over time.

Fibromuscular dysplasia of the renal arteries: comparison of helical CT angiography and arteriography.

OBJECTIVE: We evaluated the role of helical CT angiography rendering techniques in the assessment of renal artery fibromuscular dysplasia. MATERIALS AND METHODS: Twenty hypertensive patients (mean age, 56 years) with angiographically proven renal artery fibromuscular dysplasia were studied by CT angiography. The acquisition protocol was collimation, 3 mm; table speed, 3 mm/sec; and incremental algorithm, one. Maximum-intensity-projection and shaded-surface-display reconstructions and transverse sections were reviewed by a consensus panel to determine the sensitivity and specificity of each technique in revealing renal artery fibromuscular dysplasia. RESULTS: Helical CT angiography enabled successful diagnosis of fibromuscular dysplasia in all 20 patients. Helical CT angiography showed 31 of 34 pathologic arteries and 33 of 38 lesions. Aneurysms (>6 mm) on arteriography (n = 12) were revealed in 83% of transverse sections, 75% of maximum-intensity-projection reconstructions, and 58% of shaded-surface-display reconstructions. Lesions that had a string of pearls appearance on arteriography (n = 19) were shown in 53% of transverse sections, 84% of maximum-intensity-projection reconstructions (p < .05 compared with transverse sections), and 74% of shaded-surface-display reconstructions. Stenoses (n = 7 on arteriography) were revealed in 57% of transverse sections, 71% of maximum-intensity-projection reconstructions, and 57% of shaded-surface-display reconstructions. Maximum intensity projection alone revealed 30 (79%) of the 38 angiographic lesions; however, using both maximum intensity projections and transverse sections increased the sensitivity to 87%. CONCLUSION: Helical CT angiography, especially the combination of transverse sections and maximum-intensity-projection reconstructions, can reliably reveal renal artery fibromuscular dysplasia. However, because some lesions may not be shown, arteriography with pressure measurements remains the only technique that can assess the physiologic significance of the dysplasia.