CO2 and gadopentetate dimeglumine as alternative contrast agents for malfunctioning dialysis grafts and fistulas

Magnetic Resonance Techniques in Hemodialysis access Management

In this review we describe current applications and future perspectives of MR angiography, MR flow quantification, and interventional MRI in hemodialysis access management. Each section starts with a brief overview of the main techniques that are currently available or under development. This is followed by a survey of the pertinent literature. Each section concludes with a discussion of the reported findings and an indication of research opportunities.

Comparison of the usefulness of gadodiamide and iodine mixture versus iodinated contrast alone for prevention of contrast-induced nephropathy in patients with chronic kidney disease undergoing coronary angiography

Contrast-induced nephropathy (CIN) is a common cause of hospital-acquired renal failure. Gadolinium-based contrast agents have been proposed as alternatives to iodinated contrast in patients at high risk for CIN. The use of high-dose intraarterial gadolinium chelates in the catheterization laboratory has been investigated in only a small number of patients. We compared patients with a creatinine clearance <60 ml/min/1.73 m2 who received intravenous hydration (> or =1,500 ml) and oral n-acetylcysteine prophylaxis with those who received a gadodiamide-iodine mixture (n = 90) or iodinated contrast alone (n = 79) in the cardiac catheterization laboratory. CIN was defined as an increase of 0.5 mg/dl in serum creatine from baseline. The 2 groups were similar with respect to demographics and risk factors. Although less iodinated contrast was used in the gadolinium mixture group, there was no difference in the incidence of CIN between the 2 groups. However, the initiation of dialysis (n = 7) and death (n = 8) only occurred in the diluted gadolinium contrast group. A stepdown multivariate analysis found diabetes mellitus to be the only independent predictor of CIN (p = 0.02, odds ratio 3.35, 95% confidence interval 1.21 to 9.29, c-statistic 0.66). In conclusion, the incidence of CIN was not decreased in high-risk patients receiving a gadolinium-iodinated contrast mixture versus iodinated contrast alone.

Use of gadolinium contrast adrenal venography for the assessment of primary aldosteronism in a patient with iodine allergy

Primary aldosteronism is a relatively common cause of secondary hypertension. It is often important to diagnose this disease accurately, since appropriate surgical therapy may result in cure of the disease. Assessment of the laterality of adrenal hyperfunction is possible using adrenal venous sampling of steroid hormones, but this procedure may not be feasible in patients with allergy to iodinated radiocontrast agents. In this paper, we report a patient with primary aldosteronism who was found to have bilateral adrenal tumors on CT. Because preoperative localization of the hyperfunctioning tumor was important, adrenal venous sampling and venography was performed by a highly-experienced radiologist using the MRI contrast agent gadolinium. After reviewing the data, the patient received a right adrenalectomy. This case report demonstrates that it was possible to perform adrenal venography using gadolinium in this patient, however the safety and efficacy should be re-assessed in individual cases.

The role of interventional radiology in management of patients with end-stage renal disease

The aim of the paper is to review the role of interventional radiology in the management of hemodialysis vascular access and complications in renal transplantation. The evaluation of patients with hemodialysis vascular access is complex. It includes the radiology/ultrasound (US) evaluation of the peripheral veins of the upper extremities with venous mapping and the evaluation of the central vein prior to the access placement and radiological detection and treatment of the stenosis and thrombosis in misfunctional dialysis fistulas. Preoperative screening enables the identification of a suitable vessel to create a hemodynamically-sound dialysis fistula. Clinical and radiological detection of the hemodynamically significant stenosis or occlusion demands fistulography and endovascular treatment. Endovascular prophylactic dilatation of stenosis greater than 50% with associated clinical abnormalities such as flow-rate reduction is warranted to prolong access patency. The technical success rates are over 90% for dilatation. One-year primary patency rate in forearm fistula is 51%, versus graft 40%. Stents are placed only in selected cases; routinely in central vein after dilatation, in ruptured vein and elastic recoil. Thrombosed fistula and grafts can be declotted by purely mechanical methods or in combination with a lytic drug. The success rate of the technique is 89-90%. Primary patency rate is 8-26% per year and secondary 75% per year. The most frequently radiologically evaluated and treated complications in renal transplantation are perirenal and renal fluid collection and abnormalities of the vasculature and collecting system. US is often the method of choice for the diagnostic evaluation and management of the percutaneous therapeutic procedures in early and late transplantation complications. Computed tomography and magnetic resonance are valuable alternatives when US is inconclusive. Renal and perirenal fluid collection are usually treated successfully with percutaneous drainage. Doppler US, magnetic resonance angiography and digital subtraction angiography have a principle role in the evaluation of vascular complications of renal transplantation and management of the endovascular therapy. Stenosis, the most common vascular complication, occurs in 1-12% of transplanted renal arteries and represents a potentially curable cause of hypertension following transplantation and/or renal dysfunction. Treatment with percutaneous transluminal renal angioplasty (PTRA) or PTRA with stent has been technically successful in 82-92% of the cases, and graft salvage rate has ranged from 80 to 100%. Restenosis occurs in up to 20% of cases, but are usually amenable to repeated PTRA. Complications such as arterial and vein thrombosis are uncommon. Intrarenal A/V fistulas and pseudoaneurysms are occasionally seen after biopsy, the treatment requires superselective embolisation. Urologic complications are relatively uncommon, predominantly they consist of the urinary leaks and urethral obstruction. Interventional treatment consists of percutaneous nephrostomy, balloon dilation, insertion of the double J stents, metallic stent placement and external drainage of the extrarenal collections.

Gadolinium-based percutaneous coronary intervention in a patient with renal insufficiency

We report the first case of using gadolinium as a contrast agent to perform percutaneous coronary intervention in a patient with an acute coronary syndrome and a history of renal insufficiency. The procedure was well tolerated without any complications or nephrotoxicity. The images obtained with gadolinium were of good quality.

Gadolinium-enhanced digital subtraction angiography of hemodialysis fistulas: a diagnostic and therapeutic approach

OBJECTIVE

The aim of our study was to evaluate the feasibility, safety, and potential role of the contrast agent gadoterate meglumine for digital subtraction angiography as a single diagnostic procedure or before percutaneous transluminal angioplasty of malfunctioning native dialysis fistulas.

MATERIALS AND METHODS

Over a 20-month period, 23 patients (15 women, eight men) with an age range of 42-87 years (mean, 63 years) having end-stage renal insufficiency and with recent hemodialysis fistula surgical placement underwent gadoterate-enhanced digital subtraction angiography with a digital 1024 x 1024 matrix. Opacification was performed on the forearm, arm, and chest with the patient in the supine position using an injection (retrograde, n = 14; anterograde, n = 8; arterial, n = 1) of gadoterate meglumine into the perianastomotic fistula segment at a rate of 3 mL/sec for a total volume ranging from 24 to 32 mL. Percutaneous transluminal angioplasty was performed in three patients and required an additional 8 mL per procedure. Examinations were compared using a 3-step confidence scale and a two-radiologist agreement (Cohen's kappa statistic) for diagnostic and opacification quality. Tolerability was evaluated on the basis of serum creatinine levels and the development of complications.

RESULTS

No impairment of renal function was found in the 15 patients who were not treated with hemodialysis. Serum creatinine level change varied from -11.9% to 11.6%. All studies were of diagnostic quality. The presence of stenosis (n = 14) or thrombosis (n = 3) in arteriovenous fistulas was shown with good interobserver agreement (kappa = 0.71-0.80) in relation to opacification quality (kappa = 0.59-0.84). No pain, neurologic complications, or allergiclike reactions occurred. Three percutaneous transluminal angioplasty procedures (brachiocephalic, n = 2; radiocephalic, n = 1) were successfully performed.

CONCLUSION

Gadoterate-enhanced digital subtraction angiography is an effective and safe method to assess causes of malfunction of hemodialysis fistulas. It can also be used to plan and perform percutaneous transluminal angioplasty.

Gadolinium-based contrast agents in angiography and interventional radiology

Gadolinium is useful as an alternative contrast agent for diagnostic angiographic and interventional procedures in patients with renal insufficiency or a history of a severe reaction to iodinated contrast material. Gadolinium usually is used as a "problem solver" to answer specific diagnostic questions or guide interventional procedures that cannot adequately be defined with CO2 angiography. Because of dose limitations with Gd, careful planning is required prior to its use with angiography or interventional procedures.

Gadolinium chelates in angiography and interventional radiology: a useful alternative to iodinated contrast media for angiography

Gadolinium has physical properties that are well suited for radiographic imaging. Digital subtraction angiography with a gadolinium chelate as contrast medium can provide images of suitable quality for diagnosis and intervention. The overall safety profile of gadolinium-based contrast media is excellent. In particular, these contrast media are well tolerated in patients with renal insufficiency when administered intraarterially in doses of less than 0.3-0.4 mmol per kilogram body weight, with a decreased incidence of contrast medium-induced nephropathy, as compared with similar volumes of iodinated contrast material. The currently available formulations of gadolinium chelates can be injected safely into every arterial and venous structure. However, substantial data are lacking on the intraarterial use of gadolinium in patients with renal insufficiency, particularly at doses that exceed those routinely used in magnetic resonance angiography. Gadolinium chelates in appropriate volumes are useful alternative contrast media in selected high-risk patients undergoing angiographic studies.

Salvage of immature forearm fistulas for haemodialysis by interventional radiology

BACKGROUND

The goal of this article is to assess the value of endovascular techniques for the salvage of fistulas that fail to mature.

METHODS

Over a 6-year period, 52 dysfunctional and 17 thrombosed immature forearm fistulas (mean age 10 weeks) were treated by interventional radiology. Angiography was performed by puncture of the brachial artery but dilation of underlying stenoses was performed after cannulation of the fistula itself, whenever possible, with a balloon never smaller than 5 mm. Embolization or ligation of any type of vein was never indicated and never performed. For thrombosed fistulas, significant clots were removed by manual catheter-directed aspiration. A covered stent (Passager) was used in cases of dilation-induced rupture not controlled by balloon tamponade.

RESULTS

An underlying stenosis was diagnosed in 100% of cases. Half of them were located in the anastomotic area. The initial success rate of interventional radiology was 97%. Dilation-induced rupture occurred in nine cases (13%) but stents were necessary in only two cases. The rate of significant clinical complications was 2.8% (bacteraemia, pseudoaneurysm). Primary and secondary patency rates at 1 year were 39 and 79%, respectively.

CONCLUSIONS

Delayed maturation of native fistulas should lead systematically to imaging as an underlying stenosis is diagnosed in all cases. Interventional radiology can treat the majority of cases and achieve a 97% success rate but early recurrence of stenoses can occur. Multidisciplinary re-evaluation of the patient must, therefore, be performed after radiological salvage of the fistula.

Evaluation of renal arteries with use of gadoterate meglumine-, CO(2)-, and iodixanol-enhanced DSA measurements versus histomorphometry in renal artery restenosis in rabbits

PURPOSE

To experimentally evaluate gadolinium (Gd)-, carbon dioxide (CO(2))-, and iodixanol-enhanced digital subtraction angiography (DSA) versus histomorphometry in the assessment of renal artery stenosis.

MATERIALS AND METHODS

Fifteen male New Zealand White rabbits weighing 4.0 kg underwent percutaneous catheterization. Renal artery stenosis was induced by bilateral overdilation-deendothelialization (balloon diameter = 2 mm). The percentage of artery overdilation was 33%. After 4 weeks, the rabbits were randomized into two groups: group A underwent right-sided therapeutic percutaneous transluminal renal angioplasty (PTRA) (balloon diameter = 1.5 mm). After another 4 weeks, the renal arteries were evaluated by gadoterate-, iodixanol-, and CO(2)-enhanced selective quantitative DSA. The rabbits were then killed and renal arteries were perfusion-fixed for 60 minutes. Serial orcein-stained 4-um-thick slices were prepared for histomorphometry.

RESULTS

Based on morphometric data of single-stenosis versus post-PTRA restenosis lesions, no significant difference was observed between Gd- and iodixanol-enhanced quantitative DSA (r(2) > 0.95), although the iodine/Gd density ratio was equal to 3.5. Carbon dioxide less reliably allowed quantitative DSA (r(2) < 0.75).

CONCLUSION

Gd-based contrast agents represent a highly reliable alternative in experimental quantitative DSA evaluation of renal artery restenosis.

Gadolinium contrast agents: their role in vascular and nonvascular diagnostic angiography and interventions

Gadolinium-based contrast agents can be used for diagnostic and interventional angiographic procedures to reduce contrast-related nephrotoxicity or in patients with a history of severe allergic reaction to iodine-containing contrast material. These agents are best used in conjunction with CO(2) to complete nondiagnostic CO(2) angiograms and to monitor the progress of a percutaneous intervention. However, the total volume of gadolinium that can be administered, the reduced quality of gadolinium digital subtraction angiography images, and the increased cost of the gadolinium-based agents can limit their use.