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At least 325 records · Page 18Linked to original sources
PubMed2002

Three-dimensional phase-contrast magnetic resonance angiography: a useful clinical adjunct to gadolinium-enhanced three-dimensional renal magnetic resonance angiography?

OBJECTIVE: To assess the value of three-dimensional (3D) phase-contrast (PC) magnetic resonance angiography (MRA) after gadolinium (Gd)-enhanced 3D MRA for renal artery imaging. METHODS: Twenty-one patients with suspected renal artery hypertension were reviewed. All studies included Gd-enhanced 3D MRA and 3D PC MRA. Blinded interpretation of the images was performed for each technique independently and in combination. Conventional X-ray angiography was used for diagnostic correlation when available. RESULTS: Renal artery stenosis was present in 7 (16.3%) of 43 renal arteries, confirmed by X-ray angiography. MRA images demonstrated 100% sensitivity and 74% specificity for Gd-enhanced 3D MRA and 100% sensitivity and 94% specificity for 3D PC MRA. All vessels were diagnosed correctly when both image sets were viewed. CONCLUSION: 3D PC MRA can improve the specificity of renal MRA by decreasing the number of false-positive Gd-enhanced 3D MRA interpretations.

Female↗
PubMedDate not supplied

Diagnosis of hepatocellular carcinoma using digital subtraction imaging with the contrast agent, Levovist: comparison with helical CT, digital subtraction angiography, and US angiography.

Digital subtraction imaging was compared to helical CT, DSA, and US angiography to assess its usefulness in the evaluation of vascularity in hepatocellular carcinoma (HCC). Digital subtraction imaging using Levovist as the contrast agent was performed in 41 patients with 43 nodules (22 men and 19 women, aged 50 to 83 years; mean age, 65 years; mean maximum tumor diameter, 27.8+/-17.1 mm). Digital subtraction imaging showed hypervascular enhancement in 39 of the 43 nodules (91%). Helical CT showed areas of high attenuation in 40 of the 43 nodules (93%), while DSA and US angiography showed positive enhancement in 38 and 43 of the 43 nodules (88% and 100%), respectively. Digital subtraction imaging is useful for evaluating vascularity in HCC when the tumor can be visualized with non-enhanced US angiography.

Aged↗
PubMedDate not supplied

[Complications in cerebral angiography. A study of 6698 cerebral angiographies].

The complications of 6,698 cerebral angiographies performed from 1979 to 1985 in 2,503 patients were analysed. In 5.24% of the patients (1.95% of the angiopathies) temporary complications could be observed. Temporary neurologic-psychiatric complications occurred in 1.96% of the patients (0.73% of the angiographies), most of them in middle-aged patients and in the presence in the presence of diffuse cerebrovascular disease. In 0.12% of the patients (0.05% of the angiographies) a permanent damage was recorded.

Age Factors↗
PubMed1991

[Development of a new digital angiography system--improvement of rotational angiography and three dimensional image display].

The prototype of a rotational digital angiography system, has been improved to expand its range of application. The new system features an improved hardware configuration and new digital processing device. The system, called "computerized dynamic stereoradiography", is based on rapid transverse rotation of the X-ray apparatus, serial circumferential radiography and binocular stereographic imaging. The new digital processing device was included in the apparatus to provide rotational digital angiography. In use, mask exposures are first taken and all data are collected on a real-time basis into frame memories. Immediately afterwards, the X-ray apparatus is returned to the starting point and and live images are obtained. Subtraction images of all frames can be produced by a keyboard operation that requires less than 10 seconds. Three-dimensional images are rendered by two display systems with a 5 degree angle of difference. These images move at the same speed of rotation of two cathode ray tubes with 1,024 lines per screen, so that optical 3-D images can be observed. Digital angiography without subtraction is also available in the new system in both rotational and sequential modes. This is particularly useful when examining emergency patients and those who cannot hold their breath during X-ray exposure. This paper presents the principle and theory of the new system, and discusses its potential for overcoming the problems presented by current angiographic procedures in clinical practice.

Angiography, Digital Subtraction↗
PubMed1991

[Magnetic resonance angiography--the start of the end of conventional angiography?].

Magnetic resonance angiography (MRA) is a new, non-invasive technique using magnetic resonance imaging to create projection images of vessels. The article gives a simplified explanation of the basic principles involved, and presents the preliminary experiences at Rikshospitalet, the National Hospital of Norway, using magnetic resonance angiography in the study of carotid and renal arteries. It is concluded that this method holds promise for more extensive use in the future. The method is likely to replace at least some of the routine conventional angiography performed today.

Angiography↗
PubMed1988

Intravenous digital subtraction angiography of the precerebral and cerebral arteries in patients with TIA. A comparison with conventional angiography.

A study of the diagnostic utility of both intravenous digital subtraction angiography (IV-DSA) and conventional angiography of precerebral and cerebral arteries is presented. The series comprised 60 patients with TIA, who underwent the two procedures with a mean interval of 16 days. Conventional angiography was generally superior to IV-DSA, and this was particularly marked in the siphons and cerebral arteries. Only the excellent IV-DSA examinations obtained in a few patients with TIA could be accepted as final pre-operative procedures. Accurate imaging of the lesions and collateral flow pattern usually required intra-arterial injections, and intra-arterial DSA is now usually preferred.

Aorta, Thoracic↗
PubMed1983

Digital video subtraction angiography and duplex scanning in assessment of carotid artery disease: comparison with conventional angiography.

Digital video subtraction angiography (DVSA) and duplex scanning were compared to conventional angiography with regard to their accuracy in quantifying internal carotid artery disease. A classification of 108 carotid arteries available for comparison was made into five groups: normal (14), stenosis to 20% (15), stenosis from 20% to 49% (19), stenosis from 50% to 99% (44), and occlusion (16). The overall agreement corrected for chance (K) for DVSA was 0.738 +/- (SE) 0.049, which was better than for duplex scanning (K = 0.610 +/- 0.055). For hemodynamically significant disease (greater than or equal to 50% diameter reduction), both techniques were highly accurate: DVSA had a sensitivity of 95% (57/60) and a specificity of 92% (44/48); the sensitivity of duplex scanning was also 95% (57/60) and the specificity 85% (41/48). The accuracy in differentiating between high-grade stenosis and occlusion was 98% (59/60) for duplex scanning and 100% (60/60) for DVSA. The most prominent limitation of duplex scanning was its overestimation of disease in normal and minimally diseased arteries. Its specificity for ruling out any degree of disease was only 21% (3/14). DVSA had a poor predictive value of a normal test, 55% (12/22), and was more than one category wrong seven times, while this occurred only three times for duplex scanning. At the present time carotid endarterectomy without conventional angiography is only advocated when there is complete agreement between DVSA and duplex scanning.

Angiography↗
PubMed1982

Digital angiography: introducing digital techniques to clinical cerebral angiography practice.

Digital subtraction angiography provides a computerized radiographic method of imaging the vascular system. These computer techniques may be used with arterial catheterization (digital arterial angiography) and with intravenous contrast injection (digital venous angiography). Both methods are changing the diagnostic evaluation and therapeutic follow-up of patients with cerebrovascular disease.

Brachiocephalic Trunk↗
PubMed1982

Digital subtraction angiography as a method of screening for coronary artery disease during peripheral vascular angiography.

Since myocardial infarction is the major cause of perioperative and postoperative death following peripheral vascular surgery, an accurate method of screening for coronary artery disease in this group of patients is needed. Digital subtraction angiography (DSA) with the use of intra-arterial aortic root injection of contrast material was evaluated as a method of screening for coronary artery disease in patients undergoing angiography for peripheral vascular disease. The feasibility of this method was demonstrated in animal experiments. Fifteen milliliters of Renografin-76 was power injected into the aortic root of seven anesthetized 20 kg mongrel dogs. Normal coronary artery anatomy was clearly demonstrated with DSA, and a series of iatrogenically created stenoses and occlusions were accurately identified. Excellent definition of patent grafts to the left anterior descending and circumflex coronary arteries was obtained in two dogs that had undergone previous coronary artery bypass grafting. A balloon occluder on one graft was used to demonstrate partial and near-total obstruction of the bypass graft. We are currently studying the use of aortic root injections using DSA to determine coronary artery disease in patients having standard angiography for peripheral vascular disease. Adequate visualization of coronary arteries and bypass grafts with only 20 ml of contrast has been obtained. The potential ability of this technique to identify and allow treatment of life-threatening coronary artery lesions in patients prior to or simultaneously with peripheral vascular surgery may result in reduced mortality.

Angiography↗
PubMed1995

[Value of coronary angiography in the diagnosis of coronary artery disease of the transplanted heart. Coronary angiography and arteriosclerosis of the graft].

The diagnostic value of coronary angiography, a widespread method of detection of transplant coronary artery disease, was studied in 17 cardiac transplant patients with reference to histological examination. In the 6 coronary segments studied, the only significant but weak correlation that was found was for the distal left anterior descending artery: the correlations were not statistically significant in the other 5 segments. Coronary angiography underestimated lesions and false negative results were frequently reported (66 and 27% respectively). The limitations of coronary angiography may be explained by the technical artefacts related to both methods of evaluation and the anatomically diffuse and distal nature of transplant coronary artery atherosclerosis. A more reliable diagnostic method would seem to be required in view of the clinical importance of this pathology.

Coronary Angiography↗
PubMedDate not supplied

Coronary angiography and revascularization: defining procedural indications through formal group processes. The Canadian Revascularization Panel, the Canadian Coronary Angiography Panel.

OBJECTIVES: To summarize the process and extent of interphysician agreement within two panels convened to derive indications for the appropriate use of coronary angiography and for coronary revascularization procedures. PARTICIPANTS: Two panels, each with nine practitioners. METHODS: Panelists rated the appropriateness of intervention for a comprehensive set of indications for each procedure. Indications were brief profiles created by combining and permuting clinical characteristics pertinent to case selection for intervention. Ratings were first made at home, with a second round at the panel meeting following open discussion. Final rankings of indications as 'appropriate', 'uncertain' or 'inappropriate' were based on the pattern of panelists' responses on a nine-point scale, including the median rating and extent of agreement among panelists. Agreement was defined as at least seven panelists' ratings within the three-point region containing the median rating. Panelists were later mailed a much-reduced list of indications for which there was agreement on appropriateness. These were re-rated on a necessity scale. A procedure was rated 'necessary' only if a physician was ethically obligated to recommend it as the preferred treatment option. RESULTS: For appropriateness of angiography, agreement occurred in 38.2% of indications in round 1 and 64.4% in round 2 (P < 0.0001). For coronary artery bypass graft (CABG) versus medical therapy, the corresponding increase was from 43.5 to 54.0% (P < 0.0001). Agreement on necessity of angiography occurred for 44.3% of scenarios. For indications where CABG alone was appropriate, agreement on necessity was 56%. However, for indications where percutaneous transluminal coronary angioplasty (PTCA) could be regarded as the first-line intervention, agreement on necessity was only 5%. CONCLUSIONS: A two-step panel process permitted considerable convergence of panelists' ratings, highlighting the importance of formal panel methods in setting utilization management criteria. However, the extent of continuing disagreement on ratings underscores the need to avoid a forced consensus; instead, divergent opinions should be taken as indicative of uncertainty about the appropriateness of intervention. Interpanelist agreement on necessity ratings was modest, but may help in setting benchmarks to assess possible underprovision of invasive cardiac services in Canada.

Angioplasty, Balloon, Coronary↗
PubMed1995

Acute subarachnoid haemorrhage: 3D time-of-flight MR angiography versus intra-arterial digital angiography.

To evaluate the efficacy and reliability of 3D time-of-flight MR angiography (TOF MRA) as a noninvasive procedure, 27 patients with acute subarachnoid haemorrhage (SAH) were studied with MRA immediately before or after intra-arterial digital subtraction angiography (DSA).3DTOF MRA was performed with an axial slab of 60 mm centered on the circle of Willis and isotropic voxels. DSA showed 22 aneurysms and 1 dural arteriovenous fistula in 21 patients; the aneurysms ranged in size from 2 to 8mm. MRA failed to show 2 small aneurysms, at the origin of the posterior and anterior communicating arteries. The 3D display of the intracranial vessels obtained with maximum intensity projection (MIP) or targetted MIP sometimes rendered the aneurysms better than DSA. However, due to its high spatial resolution, DSA more clearly defined the overall anatomy of the walls of the normal and abnormal vessels.

Acute Disease↗
PubMed1995

Magnetic resonance angiography of supratentorial tumours: comparison with selective digital subtraction angiography.

We compared magnetic resonance angiography (MRA) and intra-arterial digital subtraction angiography (IADSA) in the study of brain tumours and assessed the utility of gadolinium-enhanced MRA. We studied 17 patients with supratentorial brain tumors. The entire brain was imaged with multiple overlapping thin volume acquisitions. After IV injection of gadolinium-DTPA, a single thick-slab MRA acquisition was performed. Standard three-dimensional (3D-TOF) acquisitions (in six patients) and 3D-TOF with magnetization transfer prepulse and tilted optimisation nonsaturing radiofrequency excitation pulses (in 11 patients) were used. Displacement of the anterior cerebral artery, main stem and insular branches of the middle cerebral artery was seen well on unenhanced and contrast-enhanced MRA. Displacement of the lenticulostriate and anterior choroidal arteries was seen only once, after Gadolinium. Tumour encasement of the middle cerebral artery was demonstrated in one patient. Tumour vessels were seen in 2 of 8 cases before and 3 of 8 after gadolinium; Tumour hypervascularity was seen only after gadolinium, in 3 of 8 cases. Study of the veins was possible only on gadolinium-enhanced MRA. Displacement of the venous angle was seen in 4 of 7 patients in the frontal, and in all of 8 patients on the lateral projections. Early venous drainage was not seen. Patency of the dural venous sinuses was demonstrated in all patients, but in one neoplastic occlusion of a cortical vein was recognized.

Adult↗
PubMed2004

Three-dimensional time-of-flight MR angiography for evaluation of intracranial aneurysms after endosaccular packing with Guglielmi detachable coils: comparison with 3D digital subtraction angiography.

The sensitivities and specificities of three-dimensional time-of-flight MR angiography (3D-TOF MRA) and 3D digital subtraction angiography (3D-DSA) were compared for evaluation of cerebral aneurysms after endosaccular packing with Guglielmi detachable coils (GDCs). Thirty-three patients with 33 aneurysms were included in this prospective study. 3D-TOF MRA and 3D-DSA were performed in the same week on all patients. Maximal intensity projection (MIP) and 3D reconstructed MRA images were compared with 3D-DSA images. The diameters of residual/recurrent aneurysms detected on 3D-DSA were calculated on a workstation. In 3 (9%) of 33 aneurysms, 3D-TOF MRA did not provide reliable information due to significant susceptibility artifacts on MRA. The sensitivity and specificity rates of MRA were 72.7 and 90.9%, respectively, for the diagnosis of residual/recurrent aneurysm. The diameters of residual/recurrent aneurysms that could not be detected by MRA were significantly smaller than those of detected aneurysms (mean 1.1 vs mean 2.3 mm). In one aneurysm of the anterior communicating artery (ACoA), the relationship between the residual aneurysm and the ACoA was more evident on MRA than DSA images. MRA can detect the recurrent/residual lumen of aneurysms treated with GDCs of up to at least 1.8 mm in diameter. 3D-TOF MRA is useful for follow-up of intracranial aneurysms treated with GDCs, and could partly replace DSA.

Adult↗
PubMed2004

Time-of-flight MR angiography targeted to coiled intracranial aneurysms is more sensitive to residual flow than is digital subtraction angiography.

BACKGROUND AND PURPOSE: For intracranial aneurysms treated with Guglielmi detachable coils, long-term follow-up is mandatory because coil compaction may occur and aneurysms may recur. The purpose of this study was to establish a noninvasive technique to visualize residual flow in coiled aneurysms. METHODS: We designed a 3D time-of-flight (3D-TOF) MR angiography (MRA) technique targeted to depict coiled aneurysms that employed a very short TE (1.54-1.60 ms) and a high spatial resolution (0.3 x 0.3 x 0.3 mm3 with zero-filling) to diminish spin dephasing. To diminish spin saturation, image volume was carefully positioned so that the neck of the targeted aneurysm was within 2 cm of the inflow portion along the stream of blood. Fifty-one MRA images of 39 coiled aneurysms in 39 patients were compared with digital subtraction angiography (DSA) images. DSA and MRA findings were interpolated retrospectively for parent and branch arteries' patency, as well as residual flow in aneurysms. In the latest 11 MR studies, a dark-blood 3D turbo spin-echo sequence was added to MRA to negate the effect high-signal-intensity thrombus. RESULTS: MRA visualized all parent and branch arteries with DSA confirmation. MRA visualized residual flow more frequently (38 studies) than did DSA (25 studies). Residual flow space visualized with MRA was always similar to or larger than that with DSA. The dark-blood sequence completely suppressed intraluminal high signal intensity on MRA images and confirmed that the high signal intensity was not due to thrombus. CONCLUSION: TOF MRA targeted to depict coiled intracranial aneurysms is noninvasive and superior to DSA in visualization of residual flow and, hence, useful for follow-up of coiled aneurysms.

Aged↗
PubMed1995

Assessment of carotid artery stenosis by ultrasonography, conventional angiography, and magnetic resonance angiography: correlation with ex vivo measurement of plaque stenosis.

PURPOSE: Several studies have investigated the correlation between Doppler ultrasonography (DUS), angiography (CA), and magnetic resonance angiography (MRA) in the evaluation of stenosis of the carotid bifurcation. However, these studies suffer from the lack of a true control-the lesion itself-and therefore conclusions about the diagnostic accuracy of each method remain relative. To determine the absolute accuracy of these modalities, we have prospectively studied lesion size with DUS, MRA, and CA in 28 patients undergoing 31 elective carotid endarterectomies and compared the percent of carotid stenosis determined by each technique to the carotid atheroma resected en bloc. METHODS: All patients were evaluated by each modality within 1 month before the thromboendarterectomy. With DUS, stenosis size was determined by standard flow criteria. For angiography and MRA, stenosis was defined as residual lumenal diameter/estimated normal arterial diameter (European Carotid Surgery Trial criteria). At surgery the carotid atheroma was removed en bloc in all patients. Patients in whom the lesion could not be removed successfully without damage were excluded from the study. Stenosis of the atheroma was determined ex vivo with high-resolution (0.03 mm3) magnetic resonance and confirmed by acrylic injection of the specimen under pressure and measurement of the atheroma wall and lumen. RESULTS: The measurements of the ex vivo stenosis by high-resolution magnetic resonance imaging correlated closely with the size of stenosis determined by the acrylic specimen casts (r = 0.92). By ex vivo measurement, the lesions were placed in the following size categories: 40% to 59% stenosis (n = 2), 60% to 79% stenosis (n = 6), 80% to 89% stenosis (n = 7), and 90% to 99% stenosis (n = 16). CONCLUSIONS: In general, the correlation of measurements of ex vivo stenosis with all modalities was good in these severely diseased arteries, although it was better for DUS (r = 0.80; p < 0.001) and MRA (r = 0.76; p < 0.001) than for CA (r = 0.56; p < 0.05).

Aged↗
PubMed2000

Accurate measures of left ventricular ejection fraction using electron beam tomography: a comparison with radionuclide angiography, and cine angiography.

BACKGROUND: Quantitative determination of ejection fraction is predicated on precise measurement of end-diastolic and end-systolic volumes of the left ventricle. Contrast enhanced electron beam tomography (EBT), with excellent temporal and spatial resolution, has the potential for highly accurate measures of ejection fraction. METHODS: EBT protocol used a short axis scan of the left ventricle (8-12 levels, apex to base) during infusion of iodinated contrast. To assess the accuracy of the measured left ventricular ejection fraction (LVEF), we compared EBT with first-pass radionuclide angiography (RNA) and cine angiography (CINE). RESULTS: A total of 41 patients (26 men and 15 women) underwent all three tests within 1 week. Resting ejection fraction using each modality was assessed in a linear regression model to assess inter-test correlation with the other two modalities. Correlation between CINE and EBT was high (r = 0.90, intercept 4.67, p < 0.001). Similarly, correlation of CINE and RNA (r = 0.87, intercept -5.48, p < 0.001) and between EBT and RNA (r = 0.87, intercept -4.6, p < 0.001) were high. In a subset of those patients with LVEF < or = 40%, correlation was consistently high between EBT and CINE. However, correlations were poor for the comparisons between RNA and CINE (r = 0.40), and between the RNA and EBT (r = 0.47). The mean differences of measured ejection fractions between each of the imaging modality were small. However, there was only modest agreement between each of the comparisons as measured using 95% confidence interval (CI) on Bland-Altman plots. CONCLUSION: These data indicate that the LVEF results are comparable among EBT, RNA, and CINE and can be used interchangeably to assess ventricular function for LVEF > 40%. For LVEF < or = 40%, we demonstrated some disparate results between cine angiography and RNA and between EBT and RNA, indicating that CINE or EBT may provide more accurate assessment.

Cineangiography↗