Hemodialysis grafts: color Doppler flow imaging correlated with digital subtraction angiography and functional status

Twenty-two patients with hemodialysis grafts were prospectively evaluated with color Doppler flow imaging and digital subtraction angiography (DSA). Eighteen patients had normal functional parameters during hemodialysis, and four had increased venous pressure during hemodialysis. Color Doppler flow imaging allowed identification of nine macroaneurysms related to wall degeneration, two cases of spontaneous fistula formation between the graft and peripheral veins, and 20 stenoses. Use of color Doppler flow imaging led to overestimation of the degree of stenosis at the venous anastomosis when compared with use of angiography. Three cases of subclavian venous stenosis were identified only at angiography. Color Doppler flow imaging appears accurate in the detection of stenoses and seems sufficient for follow-up of normally functioning grafts. However, because of its low sensitivity for identification of proximal stenoses and the necessity of obtaining an angiogram to plan surgical or percutaneous correction, DSA remains the technique of choice.     

MR angiography versus color Doppler sonography in the evaluation of renal vessels and the inferior vena cava in abdominal masses of pediatric patients.

OBJECTIVE: Involvement of renal vessels and the inferior vena cava (IVC) plays a decisive role during operative planning for removal of abdominal masses in pediatric patients. Advantages and limitations of MR angiography and color Doppler sonography for determining these factors were evaluated. MATERIALS AND METHODS: MR angiography and color Doppler sonography were performed preoperatively in 42 neonates, infants, and children with abdominal masses and were compared with spin-echo MR imaging and with surgical findings. Variables evaluated were anatomic variants, vessel displacement, patency of vessels, collateral circulation, and intravascular tumor extension. Quality of vessel visualization was assessed in vessels not affected by tumor. RESULTS: In 88% of unaffected renal vessels, the entire vessel course could be visualized on MR angiography compared with 58% on color Doppler sonography and 43% on spin-echo MR imaging. In four of nine cases, color Doppler sonography revealed an accessory renal artery, whereas MR angiography revealed these variants in seven of nine cases. MR angiography showed 79% and color Doppler sonography 66% of displaced vessels. Unlike MR angiography, color Doppler sonography did not reveal five stenotic renal veins because they could not be completely imaged. In two cases, however, MR angiography falsely indicated an occlusion of the IVC, whereas color Doppler sonography showed residual flow. CONCLUSION: Anatomic variants, vessel displacement, collateral circulation, and neoplastic vessel infiltration were revealed more accurately by MR angiography than by color Doppler sonography. In cases in which patency of the IVC is unclear on MR angiography, color Doppler sonography should also be performed.     

Imaging of hemodialysis fistulas: limitations of MR angiography

The clinical feasibility and utility of a three-dimensional (3D) MR angiography (MRA) were evaluated in 20 patients with hemodialysis fistulas. All patients had well functioning shunts and were imaged with a fast imaging in steady precision (FISP) flow rephased and flow dephased sequence. For comparison digital subtraction angiography and color-coded image directed Doppler sonography were used. Of 20 patients studied, 4 interrupted the MR examination due to pain in the shoulder of the extremity imaged. Of the 16 remaining fistulas only 2 were completely displayed on MR including feeding artery, anastomosis, and draining vein(s) on the MRA. Although 15 of 16 feeding arteries were shown by MRA, 10 of 16 draining veins and 14 of 16 anastomoses of the fistulas showed signal voids due to a lack of rephasing. Superimposing the MRA on the dephased images helped to demonstrate the shunt in another four patients having normal shunts. Thus, the utility of 3D MRA in imaging of hemodialysis fistulas is limited by technical problems and by patient's cooperation.     

Assessment of the vascularization of neuroendocrine tumors by stimulated acoustic emission of SH U 508A ultrasound contrast agent and color or power Doppler sonography

RATIONALE AND OBJECTIVES: To assess the vascularization of neuroendocrine tumors by stimulated acoustic emission (SAE) of SH U 508A during the blood pool phase in comparison with contrast-enhanced Doppler sonography. METHODS: Thirty-six patients with neuroendocrine tumors received contrast-enhanced Doppler sonography and 21, an additional SAE. To classify tumor perfusion on Doppler sonography, a 4-step rating score was introduced: (1) no vessels (hypoperfusion); (2) one feeding or central vessel (hypoperfusion); (3) some vessels (hyperperfusion); and (4) disseminated vessels (hyperperfusion). In 36 patients, 1 pancreatic primary tumor, 33 liver metastases, 1 splenic metastasis, and 1 lymph node metastasis were examined. Results were correlated with biphasic spiral CT (n = 35) and angiography (n = 2). RESULTS: Arterial-phase CT and digital subtraction angiography revealed 18 hyper- and 18 hypoperfused lesions. Contrast-enhanced Doppler correctly classified 15 of 18 patients (83%) with hyperperfused lesions as well as 16 of 18 (89%) hypoperfused tumors by applying the rating score. SAE correctly identified 4 of 9 hyperperfused lesions (44%), 2 were isoperfused compared with normal liver tissue (22%), and 3 were hypoperfused (33%). Of 12 hypoperfused lesions, 11 were classified correctly (92%), and 1 showed isoperfusion. Hence, the positive and negative predictive values for SAE were 80% and 69%, respectively. For contrast-enhanced Doppler sonography, positive and negative predictive values were 88% and 84%, respectively. CONCLUSIONS: Blood pool SAE failed to determine subtle tumor perfusion correctly. The rating score for contrast-enhanced Doppler sonography characterized tumor perfusion with high accuracy. The use of a contrast agent significantly improved perfusion characterization.     

Stenosis detection with MR angiography and digital subtraction angiography in dysfunctional hemodialysis access fistulas and grafts

PURPOSE: To prospectively assess three-dimensional contrast material-enhanced magnetic resonance (MR) angiography for stenosis depiction in malfunctioning hemodialysis arteriovenous fistulas (AVFs) and grafts (AVGs), as compared with digital subtraction angiography (DSA). MATERIALS AND METHODS: Ethical review board approval and written informed consent were obtained. MR angiography and DSA were performed in 51 dysfunctional hemodialysis fistulas and grafts in 48 consecutive patients. Vascular tree of accesses was divided into between three and eight segments depending on access type (AVF or AVG) and length of venous outflow. Images obtained with MR and DSA were interpreted by two MR radiologists and two interventional radiologists, respectively, who were blinded to information from each other and other studies. DSA was reference standard for stenosis detection. Sensitivity, specificity, and predictive values with 95% confidence intervals (CIs) of contrast-enhanced MR in detection of vascular segments containing hemodynamically significant (> or =50%) stenosis were calculated. Linear-weighted kappa statistic was calculated for contrast-enhanced MR and DSA to determine interobserver agreement regarding stenosis detection. RESULTS: A total of 282 vascular segments were evaluated. Contrast-enhanced MR depicted three false-positive stenoses and all but two of 70 significant stenoses depicted with DSA. Sensitivity, specificity, and positive and negative predictive values of MR in detection of vessel segments with significant stenoses were 97% (95% CI: 90%, 99%), 99% (95% CI: 96%, 100%), 96% (95% CI: 88%, 99%), and 99% (95% CI: 97%, 100%), respectively. MR demonstrated significant stenosis in four of five nondiagnostic DSA segments, whereas DSA showed no significant stenosis in four nondiagnostic MR segments. Linear-weighted kappa statistic for interobserver agreement regarding stenosis detection was 0.92 (95% CI: 0.89, 0.95) for MR and 0.95 (95% CI: 0.92, 0.97) for DSA. CONCLUSION: MR angiography depicts stenoses in dysfunctional hemodialysis accesses but has limited clinical value as result of current inability to perform MR-guided access interventions after stenosis detection. MR of dysfunctional access should be considered only if nondiagnostic vascular segment is present at DSA.     

Endoluminal repair of peripheral arterial aneurysms: 4-year experience with the cragg endopro system I

PURPOSE: To assess the efficiency and long-term patency of the Cragg EndoPro System I in patients with peripheral arterial aneurysms. MATERIALS AND METHODS: In 10 patients, 13 stent-grafts were used to treat 15 arterial aneurysms. Aneurysms were located in the common iliac (n = 4), superficial femoral (n = 4), popliteal (n = 3), and subclavian arteries (n = 2), and in a femoropopliteal bypass-graft (n = 2). Follow-up ranged between 2 and 46 months (mean, 36 months). Examination included clinical status, color-coded duplex sonography, computed tomography angiography, and intra-arterial digital subtraction angiography (DSA). RESULTS: Technical success was achieved in all patients. Primary patency was four of four in iliac vessels and three of nine in non-iliac vessels; secondary patency in noniliac vessels was four of nine. Repairs included one local lysis, four percutaneous transluminal angioplasties, one surgical thrombectomy, and one bypass surgery. Stent wire disintegration was detected in one of four iliac stent-grafts and in seven of nine noniliac stent-grafts. In noniliac grafts, significant stenoses occurred in three of nine; occlusion occurred in five of nine. One complication at the iliac level was a vessel wall penetration at the proximal stent edge, with development of a new aneurysmal formation. No late endoleaks were found. CONCLUSION: Exclusion of peripheral arterial aneurysms with stent-grafts is feasible. Long-term results are excellent in iliac vessels. Mechanical weakness of the stent assembly and frequent re-stenoses or occlusions are significant drawbacks in noniliac vessels with low patency rates.     

Carotid artery disease assessed by color Doppler flow imaging: correlation with standard Doppler sonography and angiography

Carotid artery disease was assessed in 180 patients by means of color Doppler flow imaging. Color Doppler findings in 360 carotid arteries were compared with the results of standard Doppler sonography, and color Doppler findings in 60 bifurcations were compared with the results of intraarterial angiography. The sensitivity of color Doppler for the detection of carotid disease was 100% when compared with angiography. The accuracy of color Doppler in classifying minor (40-60%), moderate (61-80%), and severe (81-90%) stenosis ranged from 91.3% to 97.8% vs standard Doppler sonography, and from 91.7% to 95.8% vs angiography. Whereas all occlusions were identified correctly by both color Doppler and angiography, four pseudoocclusions of the carotid artery were misdiagnosed as occluded. Characteristic features providing reliable criteria of the degree of stenosis are (1) intensity, extent, and duration of color fading; (2) postprocessed systolic peak frequency; (3) plaque extent on serial sonograms; and (4) poststenotic flow patterns. Display of hemodynamic disturbances induced by less pronounced plaques showed highly variable patterns that could not be anticipated from the plaque morphology alone. Thus, color Doppler preserves the advantages of standard Doppler and duplex sonography but provides additional information about otherwise anechoic necrotic and thrombotic material that often causes cerebral embolisms. With atherogenesis, repair mechanisms may be sustained or progression be stopped by reducing the risk factors and instituting medical treatment; thus, the application of this noninvasive technique is important.     

Carotid artery disease assessed by color Doppler flow imaging: correlation with standard Doppler sonography and angiography

Carotid artery disease was assessed in 180 patients by means of color Doppler flow imaging. Color Doppler findings in 360 carotid arteries were compared with the results of standard Doppler sonography, and color Doppler findings in 60 bifurcations were compared with the results of intraarterial angiography. The sensitivity of color Doppler for the detection of carotid disease was 100% when compared with angiography. The accuracy of color Doppler in classifying minor (40-60%), moderate (61-80%), and severe (81-90%) stenosis ranged from 91.3% to 97.8% vs standard Doppler sonography, and from 91.7% to 95.8% vs angiography. Whereas all occlusions were identified correctly by both color Doppler and angiography, four pseudoocclusions of the carotid artery were misdiagnosed as occluded. Characteristic features providing reliable criteria of the degree of stenosis are (1) intensity, extent, and duration of color fading; (2) postprocessed systolic peak frequency; (3) plaque extent on serial sonograms; and (4) poststenotic flow patterns. Display of hemodynamic disturbances induced by less pronounced plaques showed highly variable patterns that could not be anticipated from the plaque morphology alone. Thus, color Doppler preserves the advantages of standard Doppler and duplex sonography but provides additional information about otherwise anechoic necrotic and thrombotic material that often causes cerebral embolisms. With atherogenesis, repair mechanisms may be sustained or progression be stopped by reducing the risk factors and instituting medical treatment; thus, the application of this noninvasive technique is important.     

Diagnosis of portal vein thrombosis: value of color Doppler imaging.

This study was undertaken to determine the accuracy of color Doppler imaging in the diagnosis of portal vein thrombosis. Two hundred fifteen patients were studied with color Doppler imaging to determine patency of the main portal vein. Sonographic findings were confirmed in 75 patients, aged 19 to 66 years. Correlation with angiography was obtained in 13 patients, and surgical correlation was obtained in the remaining 62. Nine patients had portal vein thrombosis on the basis of these gold standards. Sonograms were classified as showing either patency or thrombosis, depending on the ability to show color flow within the main portal vein. Agreement between sonography and angiography or surgery was found in 69 patients (61 patent, eight thrombosed). One patient with a patent portal vein at sonography was found to have a thrombosed vessel at surgery, whereas five patients without portal venous flow at sonography had patent vessels at angiography (one patient) or surgery (four patients). Overall sensitivity and specificity for detection of portal vein thrombosis were 89% and 92%, with an accuracy of 92%, a false-negative rate of 0.11, a negative predictive value of 0.98, and a positive predictive value of 0.62. We postulate that the majority of errors in our study occurred in vessels that, although patent, had only sluggish flow, which could not be resolved because of technical limitations. We conclude that color Doppler imaging is a valuable screening procedure for the assessment of portal vein patency. If the sonogram shows a patent portal vein, no further studies are required. However, a lack of demonstrable flow does not always indicate thrombosis, and other imaging studies should be performed for confirmation.     

Color Doppler imaging of portosystemic shunts

This study was designed to investigate the utility of color Doppler sonography in the evaluation of portosystemic shunts. Thirty-one patients with a total of 32 shunts were imaged. The types of shunts examined included portacaval, five; mesocaval, eight; distal splenorenal (Warren), 14; and mesoatrial, five. Sonography was performed without knowledge of the status of the shunt, although the type of shunt was known before beginning the study. The sonographic studies were evaluated to determine their sensitivity and specificity on the basis of a prospective comparison with angiography or MR imaging (22 cases). The possible advantages of color Doppler over duplex Doppler sonography in evaluating portosystemic shunts were also investigated, as was the ability of color Doppler sonography to image specifically the shunt anastomoses. Color Doppler sonography successfully inferred shunt patency (17 cases) or thrombosis (five cases) in all 22 shunts for which correlative imaging was available (sensitivity = 100%, specificity = 100%). In comparing duplex with color Doppler sonography in all 32 shunts, the two techniques were almost equally effective in establishing patency in portacaval, mesocaval, and mesoatrial shunts. Duplex Doppler sonography, however, provided useful diagnostic information in only four of 14 splenorenal shunts. Color Doppler correctly inferred patency or thrombosis in all 14. Among all 32 shunts, the anastomosis was shown clearly by color Doppler in 23, probably in four, and not all in five. Our results suggest that color Doppler sonography is an excellent method for the evaluation of all varieties of surgically created portosystemic shunts. In particular, color Doppler sonography appears to be superior to duplex Doppler sonography in imaging splenorenal communications.     

Time-resolved 3D MR angiography with parallel imaging for evaluation of hemodialysis fistulas and grafts: initial experience

OBJECTIVE: We optimized a time-resolved 3D contrast-enhanced MR angiography sequence with integrated parallel imaging technique that can provide a large field of view with high temporal and spatial resolution, by which the hemodialysis access and the entire course of the inflow and outflow vessels can be imaged at a single anatomic station. Our objective was to evaluate the feasibility and usefulness of this method in the evaluation of patients referred for possible abnormalities in hemodialysis access. CONCLUSION: Time-resolved contrast-enhanced 3D MR angiography with parallel imaging has the potential to provide a rapid and comprehensive evaluation for the surveillance and diagnosis of hemodialysis access malfunctions. This technique may function as an important complement to conventional digital subtraction angiography and may be able to help guide medical management. The MR angiography protocol we present is a noninvasive, versatile, and time-efficient technique, without the need of direct graft puncture or flow interruption, and can be performed using a single injection of contrast material at a single station.     

Evaluation of abdominal aortic aneurysm after endoluminal treatment: comparison of color Doppler sonography with biphasic helical CT

OBJECTIVE: The purpose of this study is to compare color Doppler sonography with biphasic helical CT in the evaluation of abdominal aortic aneurysms after endovascular repair. MATERIALS AND METHODS: Fifty-five patients prospectively underwent both color Doppler sonography and helical CT within 7 days after treatment by endovascular stent-graft. Aneurysmal thrombosis, the patency of the grafts, and the presence of a leak were evaluated in all patients. When a perigraft leak was observed, an attempt was made to identify its origin and outflow vessels. Helical CT was considered the gold standard technique. RESULTS: Helical CT revealed aneurysmal thrombosis in 33 patients and a perigraft leak in 22 patients. In five patients, helical CT detected a small perigraft leak not shown by color Doppler sonography. In three patients with suboptimal examinations, color Doppler sonography revealed a suspected perigraft leak that was not confirmed by helical CT. In these eight patients, the perigraft leak was sealed or no longer observed during follow-up. Compared with enhanced helical CT, the sensitivity and specificity of color Doppler sonography for the diagnosis of a perigraft leak were 77% and 90%, respectively. In seven other patients, helical CT was superior to color Doppler sonography in detecting the origin of the perigraft leak and the outflow vessels. Two iliac artery dissections and one distal migration of the prosthesis were revealed only by helical CT. CONCLUSION: Although color Doppler sonography may detect substantial perigraft leaks, helical CT is superior for detecting the origin of the perigraft leak, the outflow vessels, and the detection of complications related to the procedure.     

Indium-111-labeled leukocyte scintigraphy in hemodialysis access-site infection

Bacterial sepsis, a significant complication of chronic hemodialysis, is generally the result of infection at the vascular access site. We retrospectively reviewed the utility of indium-111-(111In) labeled autologous leukocyte scintigraphy in 26 patients (30 scans) with synthetic vascular grafts, on chronic hemodialysis, in whom hemodialysis access site infection was a diagnostic consideration. Leukocyte scintigraphy correctly identified all fifteen access-site infections; there was one false-positive study, for an overall sensitivity and specificity of 100% and 93%, respectively. Of particular significance is the fact that in nine (60%) of the fifteen access-site infections, physical examination was normal. Our data indicate that 111In-labeled leukocyte scintigraphy is a useful procedure for the diagnosis of hemodialysis access-site infection, and it is especially valuable when physical examination of the access site is normal.     

Diabetes and peripheral arterial occlusive disease: prospective comparison of contrast-enhanced three-dimensional MR angiography with conventional digital subtraction angiography

OBJECTIVE: The purpose of this study was to compare contrast-enhanced three-dimensional MR angiography with conventional digital subtraction angiography (DSA) for identifying and evaluating arteries of the distal calf and foot in diabetic patients with severe arterial occlusive disease who will undergo distal bypass surgery. SUBJECTS AND METHODS: Twenty-four feet of 24 consecutive patients with diabetes and limb-threatening lower extremity ischemia were prospectively imaged using an ultrafast three-dimensional fast low-angle shot sequence on a 1.5-T MR scanner. All patients also underwent DSA of the diseased extremity within 5 days. Images were interpreted in a randomized manner by two observers in conference. Each lower extremity was divided into seven potential arterial segments. Image analysis included the detection of patent, stenosed, or occluded vessel segments. A vascular surgeon formulated treatment plans on the basis of findings from DSA and then formulated treatment plans on the basis of findings from both DSA and MR angiography. RESULTS: MR angiography was significantly better than DSA in revealing peripheral runoff vessels (p < 0.001). In nine (38%) of the 24 patients, MR angiography showed patent pedal vessels suitable for distal bypass grafting that were not revealed by DSA. Because of the results of MR angiography, treatment plans changed in seven of the nine patients in whom patent vessels were subsequently used as target vessels for distal pedal bypass grafts. CONCLUSION: Contrast-enhanced three-dimensional MR angiography is superior to DSA in revealing patent vessel segments of the foot in diabetic patients with severe arterial occlusive disease. Contrast-enhanced three-dimensional MR angiography should be part of the diagnostic algorithm for patients in whom pedal bypass grafting is a therapeutic option.     

Perivascular color artifact: pathologic significance and appearance on color Doppler US images

A distinctive type of artifactual extravascular assignment of color was identified in 49 color Doppler ultrasound (US) examinations in 43 patients. This artifact appeared as a random localized mixture of red and blue assigned to perivascular soft tissues; the artifact varied with the cardiac cycle, being most prominent in systole and absent or less prominent in diastole. The artifact was seen in 26 patients (32 examinations) at an anastomotic site or stenotic lesion associated with surgically created arteriovenous fistulas for hemodialysis. It was also observed in ten patients with accidental iatrogenic arteriovenous fistulas (renal transplant [n = 6], femoral artery [n = 3], and iliac artery [n = 1]), five with stenotic arteries not associated with arteriovenous fistulas, and two with arterial aneurysms. The authors believe this artifact reflects perivascular tissue vibration caused by turbulent intravascular blood flow. If properly recognized and accurately interpreted, the artifact can be a valuable color Doppler US sign of underlying vascular abnormality.     

Extracranial internal carotid artery Salmonella mycotic aneurysm complicated by occlusion of the internal carotid artery: depiction by Color Doppler sonography,CT and DSA

Mycotic aneurysms of the extracranial carotid artery are rare. Seventy-four cases have been described in the medical literature and only eight secondary to Salmonella infection. To our knowledge, color Doppler sonography, computed tomography (CT), and digital subtraction angiography (DSA) findings relating to the diagnosis and follow-up of extracranial internal carotid artery mycotic aneurysm complicated by occlusion have not previously been described in the literature. We present a report of color Doppler sonography, CT, and DSA findings of a mycotic aneurysm of the right extracranial internal carotid artery due to Salmonella associated with occlusion of the internal carotid artery, promptly diagnosed and followed up using these imaging modalities.     

Arteriovenous malformations of the kidneys: diagnosis and follow-up with color Doppler sonography in six patients

We performed color Doppler sonography in six patients with arteriovenous malformations of the kidneys. The diagnosis was established by angiography in all patients. Color Doppler sonograms were obtained at a large Doppler frequency-shift range (55 cm/sec of maximal average flow velocity at zero Doppler angle) to depict high-velocity blood flow in the malformation. In all patients, the malformations were seen as focal areas of flow, portrayed as a mixing of lighter colors. These were reflected by a rapid flow rate and marked tortuosity of the vessels. The sonograms showed a small peripheral malformation that was indistinct on selective renal angiography. However, flow in normal vessels grouped in the hilum obscured lighter-color flow of a small central malformation. In three patients who had total or partial ablation of the malformations with alcohol, follow-up color Doppler sonograms showed that the focal areas of flow, represented as mixing of lighter colors, disappeared or became smaller. This study shows that color Doppler sonography is a useful noninvasive procedure for diagnosing arteriovenous malformations of the kidney.     

Non-invasive vascular imaging of peripheral vessels

The purpose of this review is to describe recent advances in non-invasive vascular imaging techniques and to discuss their current clinical applications for imaging of peripheral vessels. Principles for applying ultrasound, CT angiography (CTA), and magnetic resonance angiography (MRA) for non-invasive imaging of peripheral arteries and veins are presented. Clinical applications are reviewed for different vascular diseases, therapy planning, and follow-up studies. Conventional Doppler and color duplex sonography are the most cost-effective procedures to detect or rule out peripheral arterial occlusive disease (PAOD) and to provide specific recommendations for therapy. In the near future, contrast-enhanced MRA (CE MRA) with additional axial two-dimensional time-of-flight studies to search for non-anatomic runoff will replace diagnostic intra-arterial digital subtraction angiography (DSA) for planning of reconstructive surgery with acquisition slabs displaying projections similar to intra-arterial DSA. Color duplex sonography should also be the first non-invasive technique applied for the detection of peripheral aneurysms. Preoperative or preinterventional therapy planning of aneurysms may be performed by CTA or CE MRA. Compression ultrasound is the imaging procedure of choice in deep venous thrombosis (DVT). In the preoperative assessment of venous incompetence, color duplex sonography is the imaging technique which is sufficient in most cases. Received: 5 March 1998; Accepted: 16 March 1998     

Intravenous digital subtraction angiography in patients with femoral arteriovenous fistulas and ilio-iliac crossover graft

Fourteen patients with femoral arteriovenous (AV) fistulas and ilio-iliac crossover bypass grafts after postthrombotic occlusion of an iliac vein were studied by intravenous digital subtraction angiography (IV DSA). Digital radiography's utility may be evaluated in the demonstration of the vascular status of AV fistulas and venous return through the reopened iliac vein or ilio-iliac graft. Digital subtraction imaging is a suitable modality to plan operations, such as closure of temporary AV fistula. In follow-up studies of these cases, patency of the crossover bypass can be assessed by noninvasive DSA of the ascending veins.