Gadolinium-based contrast agents in angiography and interventional radiology

Successful Embolization of a Direct Carotid Cavernous Fistula under Gadolinium-Based Angiography

Endovascular neurointervention is typically performed with iodinated contrast medium (ICM) under fluoroscopy. However, some patients may be contraindicated to such procedures based on their sensitivity to ICM. In this report, we describe a case of successful coil embolization of a direct carotid cavernous fistula using angiography with gadolinium-based contrast agents in a patient with severe allergic reaction to ICM. The clinical decision-making for this patient was further complicated by comorbidities of renal impairment, drug allergies, and previously severe gastrointestinal bleeding.

Waiting times between examinations with intravascularly administered contrast media: a review of contrast media pharmacokinetics and updated ESUR Contrast Media Safety Committee guidelines

The pharmacokinetics of contrast media (CM) will determine how long safe waiting intervals between successive CT or MRI examinations should be. The Contrast Media Safety Committee has reviewed the data on pharmacokinetics of contrast media to suggest safe waiting intervals between successive contrast-enhanced imaging studies in relation to the renal function of the patient. CLINICAL RELEVANCE STATEMENT: Consider a waiting time between elective contrast-enhanced CT and (coronary) angiography with successive iodine-based contrast media administrations in patients with normal renal function (eGFR > 60 mL/min/1.73 m2) of optimally 12 h (near complete clearance of the previously administered iodine-based contrast media) and minimally 4 h (if clinical indication requires rapid follow-up). KEY POINTS: • Pharmacokinetics of contrast media will guide safe waiting times between successive administrations. • Safe waiting times increase with increasing renal insufficiency. • Iodine-based contrast media influence MRI signal intensities and gadolinium-based contrast agents influence CT attenuation.

Adrenal vein sampling with gadolinium contrast medium in a patient with florid primary aldosteronism and iodine allergy

We describe a 35-year-old woman who was allergic to iodine contrast medium and was diagnosed with primary aldosteronism (PA) based on functional confirmatory tests. She was suspected to have unilateral PA because of marked hypertension, spontaneous hypokalemia, high plasma aldosterone, reduced plasma renin activity, and a right hypodense adrenal tumor. She wanted to become pregnant and requested adrenalectomy instead of medical treatment with mineralocorticoid receptor antagonists. Localization of PA by adrenal vein sampling (AVS) was necessary, but angiography with iodine contrast medium was not possible because of her allergy. AVS was performed using gadolinium contrast agent (gadoterate meglumine) instead of iodine, in combination with computed tomography angiography (CTA). In AVS, before and after adrenocorticotropin (ACTH) loading, 12 blood samples were drawn from the right adrenal vein, left adrenal central vein, left adrenal common duct, left and right renal veins, and the lower inferior vena cava with only 5 mL of gadolinium medium. There were no complications during AVS. Examination revealed an elevated aldosterone/cortisol ratio on the right side, lateralized ratio of 7.4, and contralateral ratio of 0.76; the patient was diagnosed with right unilateral PA. She underwent right adrenalectomy and showed improvements in aldosterone level from 312.4 pg/mL to 83.0 pg/mL, potassium from 3.0 mEq/L to 3.9 mEq/L, and systolic blood pressure from 138 mm Hg to 117 mm Hg. In PA patients with iodine allergy, AVS can be performed safely and precisely using gadolinium contrast combined with CTA.

Gadolinium contrast balloon pulmonary angioplasty for a patient with chronic thromboembolic pulmonary hypertension and severe iodine allergy

Chronic thromboembolic pulmonary hypertension (CTEPH) is group 4 pulmonary hypertension caused by organized thrombi in the pulmonary arteries. Balloon pulmonary angioplasty (BPA) is an emerging treatment option for patients with inoperable CTEPH but needs contrast media. Therefore, management can be very difficult in patients who have severe iodine allergies. We present a case of a 61-year-old female with CTEPH. Right heart catheterization showed that the mean pulmonary arterial pressure (mPAP) was 47 mmHg. Her organized thrombi were not surgically accessible, so we performed BPA to improve her hemodynamic status. One session of BPA was performed, but the second session was halted because of iodine-induced anaphylactic shock. Despite the administration of pulmonary arterial hypertension-specific drugs for 3 months, the patient's mPAP was still 33 mmHg. CTEPH patients with mPAP ≥30 mmHg have a poor prognosis, so we decided to perform BPA using gadolinium contrast media. A total of six sessions of gadolinium contrast BPA (Gd-BPA) improved the patient's mPAP to the normal range. Gadolinium contrast media could also be used for visualizing pulmonary arteries during BPA. Our report is the first successful case of Gd-BPA, which improved the patient's hemodynamic status to the almost normal range. Gd-BPA may be an attractive treatment option for patients with inoperable CTEPH and severe iodine allergy.

Ultra-low iodine concentrations iso-attenuating with diagnostic 0.5M gadolinium in endovascular procedures to minimize the risk of contrast nephropathy: A phantom study

PURPOSE

To establish the concentrations of iodine contrast media (I-CM) iso-attenuating with 0.5M gadolinium contrast media (Gd-CM), regarded diagnostic in catheter angiography and vascular interventions in azotemic patients, at various X-ray tube potentials with correlation to skin radiation dose.

MATERIALS AND METHOD

20-mL syringes filled with 30, 40, 50, 70 and 90 mgI/mL, 0.5M Gd-CM and air were placed in a water-equivalent phantom and exposed at about 50, 60, 70, 80 and 90 kV in an X-ray angiographic system. Relative contrast between the contrast materials and the background phantom material was measured on a PACS workstation. Radiation entrance dose, measured with a dose meter and estimated from the dose-area-product (DAP), was adjusted for radiation backscatter to simulate absorbed skin dose.

RESULT

The iodine concentrations 30, 40, 50, 70 and 90 mg/mL resulted in the same relative contrast as 0.5M gadolinium at 53, 57, 62, 71 and 85 kVp, respectively. Air had lower relative contrast than all iodine concentrations at all kVp-settings except for 30 mgI/mL above 84 kVp. The measured skin radiation dose was less than 1 mGy per exposure at all kVp-settings, and around 25-30% lower than the dose estimations derived from the angiographic system's in-built DAP meter.

CONCLUSION

Low-kilovoltage X-ray technique and ultra-low concentrations of I-CM iso-attenuating with 0.5M Gd-CM may be utilizable in peripheral arteriography and endovascular interventions, to minimize the total CM-dose to avoid CIN in azotemic patients.

Comparison in accumulation of lanthanide elements among three Brassicaceae plant sprouts

Three kinds of sprouts in the Brassicaceae family of plants, namely, pink kale, radish and mustard were evaluated for the possibility of phytoremediation of lanthanides. The mustard sprout more efficiently accumulated lanthanides (e.g. 0.26 nmol La/g) than other Brassicaceae family plant sprouts (0.16 nmol La/g in the radish), however the radish sprout showed the fastest growth among three sprouts. Faster growth compensated for less efficiency in lanthanide accumulation (28 pmol La in the radish vs. 12 pmol La in the mustard) indicating that the radish is the most preferable sprout for the phytoremediation of lanthanides.

The use of gadolinium in patients with contrast allergy or renal failure requiring coronary angiography, coronary intervention, or vascular procedure

Coronary artery angiography remains an important procedure for the assessment of coronary arteries. It requires injection of iodinated contrast for the opacification of coronary arteries. Severe allergy to iodine contrast and renal insufficiency are two main problems with iodine-based contrast media. Gadolinium (Gd) has different chemical structure with no cross reactivity with iodine-based contrast media in patients with iodine allergy. The use of Gd is commonly used in contrast-enhanced magnetic resonance imaging for image enhancement, making it a potential alternative in patients in whom iodine is contraindicated. The aim of this manuscript is to review the available literature on the use of Gd in patients with contraindication to iodine contrast due to allergy or in patients with severe renal failure requiring coronary or vascular procedures.

Effects of iodinated contrast agent on diffusion weighted magnetic resonance imaging

RATIONALE AND OBJECTIVES

To evaluate the effects of iodine contrast agent on diffusion signal intensity and apparent diffusion coefficient (ADC) in diffusion-weighted imaging (DWI) studies in magnetic resonance imaging (MRI) examination just after computed tomography (CT) contrast imaging.

MATERIALS AND METHODS

On a 1.5 T MRI scanner, ADC was calculated from the signal intensity of DWI (b = 0 and 1000) using phantoms filled with contrast agent (0, 4.5, 6.0, 9.0, 30, and 60 mgI/mL). We evaluated the signal intensities of DWI and ADC in 10 patients (3 women, 7 men, 35-68 years old) examined by MRI study less than 40 minutes after injection of 100 mL of iopamidol (300 mgI/mL) for CT study.

RESULTS

The DWI signal increased until a CT value of 190 HU, but showed no changes above this value. The ADC decreased with increases in CT value. Less than 40 minutes after injection of iopamidol (300 mgI/mL) for CT scan, the signal intensity of DWI was significantly increased and ADC was significantly decreased.

CONCLUSIONS

It is necessary to recognize the rate of decrease of ADC, because it is dependent on the density of iodine contrast agents.

Gadolinium-based coronary angiography in patients with contraindication for iodinated x-ray contrast medium: a word of caution

BACKGROUND

In coronary angiography, the use of contrast agents containing iodine still defines the gold standard. In patients with contraindications for iodine exposition, gadolinium has been considered to be a safe alternative to standard iodinated contrast medium for coronary angiography. The aim of the present study was to assess the safety and technical quality of gadolinium-based coronary angiography.

METHODS

Nineteen consecutive patients with contraindication to iodinated contrast medium underwent gadolinium-based coronary angiography. Contraindications included previous anaphylactic shock or severe allergic reaction to iodinated contrast medium (n = 13) or thyrotoxicosis (n = 6). Gadolinium was diluted 1:1 with sodium chloride before application. Patients were clinically observed for potential side effects, and renal function was assessed by determination of creatinine values and calculation of creatinine clearance in pre- and postprocedural blood samples. Image quality was evaluated by two independent observers, and classified into three different categories (grade 1, high diagnostic quality; grade 2, moderate diagnostic quality; and grade 3, poor quality).

RESULTS

During angiography, a mean of 32.6 +/- 10.9 mL (range 10-45 mL) gadolinium was used. No patient developed a significant impairment of renal function within 24 hours after the examination (mean creatinine value preprocedural: 1.12 +/- 0.15 mg/dL, postprocedural: 6 hours 1.15 +/- 0.18 mg/dL, 24 hours 1.13 +/- 0.16 mg/dL) (baseline vs. 6 hours P = 0.23, baseline vs. 24 hours P = 0.66, 6 hours vs. 24 hours P = 0.12) (mean creatinine clearance preprocedural: 73.8 +/- 18 mg/dL, postprocedural: 6 hours 71.7 +/- 16.8 mg/dL, 24 hours 73.2 +/- 17.8 mg/dL) (baseline vs. 6 hours P = 0.2, baseline vs. 24 hours P = 0.71, 6 hours vs. 24 hours P = 0.21). Four patients (21%) suffered severe complications due to gadolinium application, such as malignant cardiac arrhythmias (n = 3) and hemodynamic decompensation (n = 1). Image quality was generally reduced in comparison to iodine contrast coronary angiography, but was adequate for diagnostic purposes (13 patients [68.4%] had reasonably good picture contrast [grade 2.1 +/- 0.3]; in 6 patients [31.6%], image quality was satisfactory [grade 2.6 +/- 0.13]). Opacification of distal vessels as compared to proximal segments was remarkably reduced.

CONCLUSIONS

Gadolinium-based coronary angiography is a potential alternative technique in patients with allergy to iodinated contrast medium or thyrotoxicosis with reduced, but acceptable, image quality for diagnostic purposes. Nevertheless, possible life-threatening side effects and complications have to be considered.

Magnetic resonance angiography

MRA and MRI have become increasingly important diagnostic modalities in vascular surgery. The ability to obtain cross-sectional and angiographic images by these noninvasive and non-nephrotoxic modalities represents one of the most significant advances in vascular surgery over the past decade. We review the current status of MRI and MRA in vascular surgical practice.

Value, limitations, and techniques of renal artery stenting

Percutaneous therapy for renovascular occlusive disease has become the preferred alternative to open renal artery revascularization. Angioplasty and stenting of renal artery stenoses has been shown to be a safe and effective option for severe hypertension and ischemic nephropathy. Catheter-based treatment, especially when performed with lower-profile systems can be performed with minimal morbidity and a reliably high degree of initial technical success. The long-term beneficial effects on blood pressure control and renal function, while debated, appear to be valid. In this article, data supporting the value and limitations of renal artery stenting are reviewed, and our technique for renal artery stenting using a lower-profile platform of balloons and stents is described.