Gadobutrol-enhanced moving-table magnetic resonance angiography in patients with peripheral vascular disease: a prospective, multi-centre blinded comparison with digital subtraction angiography

Clinical Efficacy of Gadobutrol: Review of Over 25 Years of Use Exceeding 100 Million Administrations

BACKGROUND

Gadobutrol has been administered more than 100 million times worldwide, since February 1998, that is, over the last 25 years. Numerous clinical studies in a broad range of indications document the long-term experience with gadobutrol.

OBJECTIVE

The aim of this study was to provide a literature-based overview on gadobutrol's efficacy in 9 approved indications and use in children.

MATERIALS AND METHODS

Efficacy results in patients of all age groups including sensitivity, specificity, accuracy, and positive/negative predictive values were identified by a systematic literature search on Embase until December 31, 2022. Nine approved indications were considered: central nervous system (CNS), magnetic resonance angiography (MRA), breast, heart, prostate, kidney, liver, musculoskeletal, whole body, and various indications in children.

RESULTS

Sixty-five publications (10 phase III, 2 phase IV, 53 investigator-initiated studies) reported diagnostic efficacy results obtained from 7806 patients including 271 children, at 369 centers worldwide. Indication-specific sensitivity ranges were 59%-98% (CNS), 53%-100% (MRA), 80%-100% (breast), 64%-90% (heart), 64%-96% (prostate), 71-85 (kidney), 79%-100% (liver), 53%-98% (musculoskeletal), and 78%-100% (children). Indication-specific specificity ranges were 75%-100% (CNS), 64%-99% (MRA), 58%-98% (breast), and 47%-100% (heart).

CONCLUSIONS

The evaluated body of evidence, consisting of 65 studies with 7806 patients, including 271 children and 7535 adults, showed that gadobutrol is an efficacious magnetic resonance imaging contrast agent for all age groups in various approved indications throughout the whole body.

Digital Subtraction Angiography (DSA) Technical and Diagnostic Aspects in the Study of Lower Limb Arteries

Cardiovascular diseases represent one of the most frequent diseases worldwide; among these, lower limb ischemia is a threatening condition, which can lead to permanent disability if not promptly and correctly diagnosed and treated. A patient’s clinical evaluation and diagnostic imaging (e.g., color-Doppler ultrasound, computed tomography angiography (CTA), and magnetic resonance imaging (MRI)) are mandatory to carefully assess arterial lesion extension and severity. Digital subtraction angiography (DSA) is a minimally invasive technique that represents the gold standard for percutaneous revascularization treatment of symptomatic patients who are refractory to medical management. However, when dealing with patients with lower limb terminal ischemia, the correct interpretation of diagnostic DSA findings is mandatory for treatment re-planning and to effectively evaluate post-treatment results and complications. The purpose of this review is to provide interventional radiologists and endovascular practitioners with an up-to-date practical guide to diagnostic angiography of the lower limbs, which is mandatory to address correct treatment decisions and post-treatment evaluation.

Improved display of abdominal contrast-enhanced MRA using gadobutrol: comparison with Gd-DTPA

AIM

To qualitatively and quantitatively compare gadobutrol with gadopentetate dimeglumine (Gd-DTPA) in abdominal contrast-enhanced magnetic resonance angiography (CE-MRA) and contrast-enhanced magnetic resonance imaging (CE-MRI) during one-stop imaging.

MATERIALS AND METHODS

This prospective, blinded, multicentre, intra-individual comparison study was approved by the institutional review board. All patients underwent gadobutrol- and Gd-DTPA-enhanced MRA and MRI. Qualitative analysis for vessels was performed using a three-point scale while quantity analysis was performed by signal-to-noise ratio (SNR). Visceral organs enhancements were also analysed. A Wilcoxon matched-pair signed-rank test was used to evaluate the quality and quantity results.

RESULTS

One hundred and twelve patients were enrolled. Quality analyses results for large vessels and small vessels of gadobutrol and Gd-DTPA were 18.38±1.51 and 6.76±1.58 and 17.87±1.84 and 6.09±1.55, respectively. Wilcoxon signed-rank tests revealed gadobutrol was significantly superior to Gd-DTPA (p=0.036) for small vessels. For large vessel quantity analysis, gadobutrol demonstrated significantly higher signal-to-noise ratios (SNR; p=0.041) than Gd-DTPA, with mean values of 948.156±349.731 and 838.925±248.197. There was no statistically significant in enhancement of liver, spleen, and renal tissue during gadobutrol- and Gd-DTPA-enhanced imaging (p>0.05). One patient reported an adverse event. Dizziness and vomiting occurred after injection of Gd-DTPA.

CONCLUSIONS

The present study demonstrates gadobutrol-enhanced MRA was superior to that of Gd-DTPA without statistical significance in visceral organ enhancement. It indicates gadobutrol may be more suitable for abdominal one-stop imaging for CE-MRA and CE-MRI by improving depiction of vessels in MRA images.

Peripheral arterial disease screening and diagnostic practice: A scoping review

Early reliable, valid screening, diagnosis, and treatment improve peripheral arterial disease outcomes, yet screening and diagnostic practices vary across settings and specialties. A scoping literature review described reliability and validity of peripheral ischaemia diagnosis or screening tools. Clinical studies in the PUBMED database January 1, 1970, to August 13, 2018, were reviewed summarising ranges of reliability and validity of peripheral ischaemia diagnostic and screening tools for patients with non-neuropathic lower leg ischaemia. Peripheral ischaemia screening and diagnostic practices varied in parameters measured such as timing, frequency, setting, ordering clinicians, degree of invasiveness, costs, definitions, and cut-off points informing clinical and referral decisions. Traditional ankle/brachial systolic blood pressure index <0.9 was a reliable, valid lower leg ischaemia screening test to trigger specialist referral for detailed diagnosis. For patients with advanced peripheral ischaemia or calcified arteries, toe-brachial index, claudication, or invasive angiographic imaging techniques that can have complications were reliable, valid screening, and diagnostic tools to inform management decisions. Ankle/brachial index testing is sufficiently reliable and valid for use during routine examinations to improve timing and consistency of peripheral ischaemia screening, triggering prompt specialist referral for more reliable, accurate Doppler, or other diagnosis to inform treatment decisions.

Gadobutrol Precedes Gd-DTPA in Abdominal Contrast-Enhanced MRA and MRI: A Prospective, Multicenter, Intraindividual Study

OBJECTIVE

To qualitatively and quantitatively compare the contrast-enhanced magnetic resonance angiography (MRA) and magnetic resonance imaging (MRI) in one-stop shop of abdominal imaging with Gadobutrol and Gd-DTPA at equimolar doses of gadolinium.

MATERIALS AND METHODS

This was a prospective designed, multiple center, intraindividual comparison study. All volunteers underwent Gadobutrol- and Gd-DTPA-enhanced MRA and MRI in one-stop shop. Qualitative analysis for large vessels and small vessels was performed by a three-point scale, while for minute small vessels, by a five-point scale. Quantitative analysis was performed for large vessels by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Visceral organ enhancements on the equilibrium phase were also analyzed. Wilcoxon matched-pair signed-rank tests were used to evaluate the qualitative and quantitative results.

RESULTS

40 volunteers were enrolled. Qualitative analyses results for large vessels, small vessels, and minute small vessels of Gadobutrol and Gd-DTPA were 20.98 ± 2.11, 6.03 ± 1.03, and 3.41 ± 1.18 and 20.01 ± 2.18, 5.28 ± 1.67, and 2.61 ± 1.40, respectively. Wilcoxon signed-rank tests revealed Gadobutrol-enhanced MRA was superior to that of Gd-DTPA significantly for small vessels (p=0.028) and minute small vessels (p=0.007). For quantitative analysis of large vessels, no statistic difference was found. Gadobutrol-enhanced MRI had higher CNR of the liver (p=0.003), spleen (p=0.001), and pancreas (p=0.001) and higher SNR of spleen (p=0.009) than those of Gd-DTPA statistically.

CONCLUSION

Our study proved Gadobutrol was superior to Gd-DTPA in qualitative analysis of CE-MRA and quantitative analysis of visceral organ enhancement on CE-MRI in abdomen of healthy volunteers. Gadobutrol may be more suitable for abdominal one-stop examination for CE-MRA and CE-MRI.

Contemporary follow-up imaging after endovascular repair of lower extremity atherosclerotic lesions

Atherosclerotic disease is currently one of the most important problems of modern medicine because it is a leading cause of increased morbidity, morbidity and mortality, and disability in the Western World. Atherosclerosis of the lower limbs (peripheral arterial disease – PAD) significantly affects the quality of life and in a considerable proportion of patients is a cause of disability. Radical treatment of PAD, both surgical and endovascular, aims at revascularisation of ischaemic tissues distal to obstructed arteries. Surveillance imaging is an important part of patient management after endovascular repair of PAD. Apart from availability and contraindications, challenges of imaging include calcifications, flow dynamics, and stent-related artefacts. The aim of this paper was to review the current literature on imaging methods for follow-up after endovascular repair of atherosclerotic lesions, with special attention paid to novel techniques. As a non-invasive modality, ultrasound is still the first-line examination, but computed tomography angiography remains a current state-of-the art technique for follow-up. However, since current imaging recommendations seem not to adhere to contemporary imaging possibilities, more attention should be paid to recent improvements in magnetic resonance angiography technology.

Gadobutrol: A Review in Contrast-Enhanced MRI and MRA

Intravenous gadobutrol [Gadovist^™ (EU); Gadavist^® (USA)] is a second-generation, extracellular non-ionic macrocyclic gadolinium-based contrast agent (GBCA) that is approved for use in paediatric (including term neonates) and adult patients undergoing diagnostic contrast-enhanced (CE) MRI for visualization of pathological lesions in all body regions or for CE MRA to evaluate perfusion and flow-related abnormalities. Its unique physicochemical profile, including its high thermostability and proton relaxation times, means that gadobutrol is formulated at twice the gadolinium ion concentration of other GBCAs, resulting in a narrower bolus and consequently, improved dynamic image enhancement. Based on >  20 years of experience in the clinical trial and real-world settings (>  50 million doses) and its low risk for developing nephrogenic systemic fibrosis (NSF), gadobutrol represents an effective and safe diagnostic GBCA for use in CE MRI and MRA to visualize pathological lesions and vascular perfusion and flow-related abnormalities in all body regions in a broad spectrum of patients, including term neonates and other paediatric patients, young and elderly adult patients, and those with moderate or severe renal or hepatic impairment or cardiovascular (CV) disease.

Gadobutrol in India-A Comprehensive Review of Safety and Efficacy

Gadobutrol is a gadolinium (Gd)-based contrast agent for magnetic resonance imaging (MRI). In India, gadobutrol is approved for MRI of the central nervous system (CNS), liver, kidneys, breast and for MR angiography for patients 2 years and older. The standard dose for all age groups is 0.1 mmol/kg body weight. The safety profile has been demonstrated in 42 clinical phase 2 to 4 studies (>6800 patients), 7 observational studies, and by assessing pharmacovigilance data of 29 million applications. Furthermore, studies in children, adults, and elderly and in patients with impaired liver or kidney function did not show any increased adverse event rate. Diagnostic efficacy was demonstrated in numerous studies and various indications, such as diseases of the CNS, peripheral and supra-aortic vessels, kidneys, liver, and breast.

Lesion Pattern in Patients With Erectile Dysfunction of Suspected Arterial Origin

Purpose: To determine the specific lesion pattern of supplying arteries in patients with cardiovascular risk factors suffering from treatment-refractory erectile dysfunction (ED). Methods: From May 2012 to August 2013, 26 men (median age 55 years) poorly responsive to phosphodiesterase-5 inhibitor therapy were evaluated for a possible vascular cause for their ED. The men were examined with penile duplex sonography and digital subtraction angiography (DSA). Arterial lesions in the common and internal iliac arteries and the internal pudendal arteries considered amenable to endovascular therapy were treated with angioplasty ± stents. Retrospectively, 2 blinded investigators independently evaluated the DSA images and categorized the vascular patterns of the erection-related arteries as normal, macroangiopathy (occlusive lesions of the internal pudendal arteries), or microangiopathy (smaller caliber arteries distal to the internal pudendal circulation with no distal arterial reconstitution). Results: Seventeen macroangiopathic lesions were successfully treated by angioplasty in 11 patients. The treated arterial lesions were mainly located in the internal (n=10) and common iliac arteries (n=2), whereas the internal pudendal artery were involved in 5 cases. Microangiopathic lesions lacking distal reconstitution were present in 7 patients, and the remaining 8 patients had normal vessels supplying the penis. Patients with macroangiopathy undergoing angioplasty had a higher prevalence of peripheral artery disease (63.6% vs 6.7%, p=0.003). Conclusion: In this preliminary series of ED patients with cardiovascular risk factors and pathologic duplex sonographic flow parameters, roughly 40% exhibited arterial lesions amenable to endovascular revascularization. In the patients with macroangiopathy, vessels upstream of the internal pudendal artery were most commonly affected. More studies are warranted to define the role of endovascular procedures in this ED subpopulation.

MR Angiography at 3 T of Peripheral Arterial Disease: A Randomized Prospective Comparison of Gadoterate Meglumine and Gadobutrol

OBJECTIVE

This large-scale randomized study aimed to show the noninferiority in terms of diagnostic performance of gadoterate meglumine-enhanced versus gadobutrol-enhanced 3-T MR angiography (MRA) using digital subtraction angiography (DSA) as the reference standard in patients with peripheral arterial occlusive disease (PAOD).

SUBJECTS AND METHODS

In this prospective international randomized double-blind phase IV trial, 189 patients were enrolled. Of them, 156 could be included in the per-protocol population for on-site assessments and 154 for off-site readings. Subjects underwent peripheral MRA, after injection of 0.1 mmol/kg of either gadoterate meglumine or gadobutrol, and DSA within 30 days. The diagnostic accuracy was evaluated and compared using a noninferiority analysis. Secondary endpoints included sensitivity, specificity, diagnostic confidence, contrast-to-noise ratio, and signal-to-noise ratio evaluations.

RESULTS

The percentage agreement between MRA and DSA for stenosis detection was similar for on-site readings for both groups (mean ± SD, 80.6% ± 16.1% with gadoterate meglumine vs 77.1% ± 19.6% with gadobutrol; 3.5% difference), and the same was true for off-site readings (73.9% ± 16.9% with gadoterate meglumine vs 75.1% ± 13.8% with gadobutrol; 1.1% difference). The noninferiority of gadoterate meglumine to gadobutrol was shown for both on- and off-site readings. Sensitivity in detecting significant stenosis (> 50%) was 72.3% for gadoterate meglumine versus 70.6% for gadobutrol, whereas specificity (92.6% vs 92.3%), diagnostic confidence (87.0% vs 86.0%), signal-to-noise ratio (165.5 vs 161.0), and contrast-to-noise ratio (159.5 vs 155.3) did not differ statistically significantly between the two groups.

CONCLUSION

Gadoterate meglumine was found to be not inferior to gadobutrol in terms of diagnostic performance in patients with PAOD undergoing 3-T contrast-enhanced MRA. No statistically significant differences were detected between the two MRA groups.

Contrast-enhanced magnetic resonance imaging in pediatric patients: review and recommendations for current practice

Magnetic resonance imaging (MRI), frequently with contrast enhancement, is the preferred imaging modality for many indications in children. Practice varies widely between centers, reflecting the rapid pace of change and the need for further research. Guide-line changes, for example on contrast-medium choice, require continued practice reappraisal. This article reviews recent developments in pediatric contrast-enhanced MRI and offers recommendations on current best practice. Nine leading pediatric radiologists from internationally recognized radiology centers convened at a consensus meeting in Bordeaux, France, to discuss applications of contrast-enhanced MRI across a range of indications in children. Review of the literature indicated that few published data provide guidance on best practice in pediatric MRI. Discussion among the experts concluded that MRI is preferred over ionizing-radiation modalities for many indications, with advantages in safety and efficacy. Awareness of age-specific adaptations in MRI technique can optimize image quality. Gadolinium-based contrast media are recommended for enhancing imaging quality. The choice of most appropriate contrast medium should be based on criteria of safety, tolerability, and efficacy, characterized in age-specific clinical trials and personal experience.

Gadobutrol: a review of its use for contrast-enhanced magnetic resonance imaging in adults and children

Since the introduction of the first gadolinium-based contrast agent (GBCA) approximately 25 years ago, magnetic resonance imaging (MRI) using GBCAs has revolutionized diagnostic and follow-up imaging of pathological lesions, with clinical applications expanded to encompass almost all fields of medicine. Intravenous gadobutrol (Gadovist™ [EU]; Gadavist(®) [USA]) is a second-generation extracellular non-ionic macrocyclic GBCA that is used in patients undergoing diagnostic contrast-enhanced MRI for visualization of pathological lesions in the CNS and all other body regions or for contrast-enhanced magnetic resonance angiography (MRA) to evaluate perfusion and flow-related abnormalities. Its unique physicochemical profile, along with the high thermostability of macrocyclic GBCAs, means gadobutrol is formulated at twice the gadolinium ion concentration of other currently licensed GBCAs. This reduces the injection volume and provides a narrower bolus, thereby improving image enhancement. Based on extensive clinical experience in a broad range of patients, including paediatric and adult patients (younger and elderly adults), and those with moderate to severe hepatic or renal impairment or cardiovascular disorders, gadobutrol is an effective and generally well tolerated extracellular GBCA for patients undergoing diagnostic contrast-enhanced MRI and contrast-enhanced MRA. As with all macrocyclic GBCAs, the potential for gadobutrol to cause nephrogenic systemic fibrosis appears to be lower than with linear GBCAs.

Multicenter, intra-individual comparison of single dose gadobenate dimeglumine and double dose gadopentetate dimeglumine for MR angiography of the peripheral arteries (the Peripheral VALUE Study)

PURPOSE

To prospectively compare single dose gadobenate dimeglumine with double dose gadopentetate dimeglumine for CE-MRA in patients with peripheral arterial occlusive disease (PAOD) using an intra-individual crossover study design in which all patients received both contrast agents in otherwise identical CE-MRA examinations.

MATERIALS AND METHODS

Institutional review board and regulatory approval were granted and all patients provided written informed consent. Sixty-eight patients (53M/15F; 62.4 ± 15.7 years) with mild-to-severe PAOD were enrolled for randomized 3-station CE-MRA with 0.1 mmol/kg gadobenate dimeglumine and 0.2 mmol/kg gadopentetate dimeglumine. Three blinded readers assessed images for vessel anatomical delineation, disease detection/exclusion, and global preference. Diagnostic performance for detection of ≥51% stenosis was determined for 53 patients who underwent DSA. Noninferiority was assessed using the Wilcoxon Signed Rank, McNemar, and Wald tests. Quantitative enhancement was compared.

RESULTS

No differences (P ≥ 0.25) were noted for any qualitative parameter at any station. Equivalence was reported in at least 62/64 patients (93.8% 3-reader agreement) for diagnostic preference. Superiority for gadobenate dimeglumine was reported by all readers for diagnostic performance (sensitivity: 80.4-88.0% versus 75.2-85.8%; specificity: 89.8-96.0% versus 88.7-94.8%; accuracy: 87.4-91.7% versus 84.9-90.6%; PPV: 84.0-92.8% versus 82.3-90.8%; NPV: 88.5-92.4% versus 85.7-91.1%). Quantitative enhancement was similar in the pelvis but significantly (P < 0.05) greater with gadobenate dimeglumine in the thigh for two readers.

CONCLUSION

Image quality and diagnostic performance on peripheral CE-MRA with 0.1 mmol/kg gadobenate dimeglumine is at least equivalent to that with 0.2 mmol/kg gadopentetate dimeglumine.

Prospective comparison of image quality and diagnostic accuracy of 0.5 molar gadobenate dimeglumine and 1.0 molar gadobutrol in contrast-enhanced run-off magnetic resonance angiography of the lower extremities

PURPOSE

To compare image quality and diagnostic accuracy of 0.5 molar gadobenate dimeglumine and 1.0 molar gadobutrol in contrast-enhanced (CE) magnetic resonance angiography (MRA) of the lower extremities interindividually.

MATERIALS AND METHODS

The study was approved by our Institutional Review Board. Written informed consent was obtained from all patients before enrollment in the study. We prospectively included 74 patients (21 women, 53 men; mean age ± SD: 67.9 ± 11.0 years) with suspected peripheral occlusive vascular disease. All patients underwent a contrast-enhanced MRA of both lower extremities with either 0.1 mL/kg body weight gadobutrol or gadobenate dimeglumine. Image quality, stenosis grade, and artifacts were assessed by two blinded, independent investigators. Signal intensity (SI), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were measured by a third investigator. Contrast agent groups were compared to each other using a two-sided Student's t-test.

RESULTS

The results did not show significant differences for SI, SNR, or CNR. Both investigators were in significant accordance (P < 0.05) with regard to stenosis detection.

CONCLUSION

We conclude that application of standard clinical doses (0.1 mL/kg body weight) of both contrast agents provides similar diagnostic results and gadolinium dose could be reduced by the application of a single dose of gadobenate dimeglumine for CE run-off MRA.

High-resolution 3D non-contrast-enhanced, ECG-gated, multi-step MR angiography of the lower extremities: comparison with contrast-enhanced MR angiography

OBJECTIVE

To determine the diagnostic value of non-contrast-enhanced, 3D-high-resolution, ECG-gated, multi-step MR angiography (non-ceMRA) of the lower extremities using a modified turbo-spin-echo technique in comparison to 1.0-molar contrast-enhanced MR angiography (ceMRA) in patients with suspected peripheral vascular disease (PVD).

METHODS

Fifty consecutive patients underwent non-ceMRA before ceMRA within the same session. We assessed examination time, image quality, localisation and severity of stenosis.

RESULTS

Examination time was shorter for ceMRA (12 ± 4 min) compared with non-ceMRA (28 ± 6 min, p < 0.001). The image quality of the aorta-iliac, femoral and combined popliteal and lower leg arteries was inferior for non-ceMRA (2.8 ± 0.8/3.3 ± 0.8/3.3 ± 0.9) versus ceMRA (4.7 ± 0.8/4.8 ± 0.6/4.8 ± 0.7) on a 5-point scale with 5 for maximum quality (p < 0.01). CeMRA offered more assessable data sets than non-ceMRA (98% vs. 90%). For detecting stenosis >50% or occlusions of pelvic and femoral arteries using non-ceMRA the sensitivity, specificity, positive and negative predictive values were 94%, 86%, 67% and 98% and for popliteal and lower leg arteries 93%, 87%, 69% and 98%, respectively.

CONCLUSION

We demonstrated that 3D non-ceMRA represents a very promising technique in patients with lower extremities PVD and could be used as an alternative if gadolinium-based contrast agents cannot be administered.

Clinical experience in timed arterial compression contrast-enhanced magnetic resonance angiography of the hand

PURPOSE

A retrospective analysis of the diagnostic performance of the timed arterial compression (TAC) technique, which allows freezing of the contrast bolus during first-pass contrast-enhanced (CE) magnetic resonance angiography (MRA) to diagnose vascular pathologies in the hand.

MATERIAL AND METHODS

A total of 14 consecutive CE-MRAs of the hand were acquired by using the TAC technique. By inflating a blood pressure cuff up to 200 mm Hg triggered to the arterial contrast filling of the hand, prolonged measurement times up to 144 seconds, with a spatial resolution of 0.59 × 0.59 × 0.8 mm(3), could be realized. Overall image qualities, arterial signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and vessel conspicuity besides the final diagnosis were evaluated.

RESULTS

All 14 TAC-CE-MRAs of the hand were successfully accomplished without any adverse events and yielded, in all cases, a final diagnosis with a high total number of vascular pathologies (57). High arterial SNR and CNR values exceeding the soil of 85 and 60, respectively, resulted. Thus, overall vessel visibility (>90%), vessel conspicuity (mean Δ signal intensity [SI]/mm = 1,193) and image quality on a per patient level (>60%) were rated as excellent or good.

CONCLUSIONS

TAC-CE-MRA of the hand offers high diagnostic performance because of its increased spatial resolution while preserving contrast, which allowed detection of tiny stenoses of the digital arteries.

Improved vessel delineation in keyhole time-resolved contrast-enhanced MR angiography using a gadolinium doped flush

PURPOSE

To prospectively assess the influence of a gadolinium doped saline flush compared with a pure saline flush on the image quality of the supra-aortic vessels using time-resolved contrast-enhanced MR angiography (4D CE-MRA) in a randomized double blind clinical trial.

MATERIALS AND METHODS

Twenty-two patients scheduled for contrast-enhanced craniocerebral MRI underwent a supplemental 4D CE-MRA covering the carotids to the superior sinus consisting of 30 dynamics of a T1-weighted 3D gradient-echo sequence (FFE) in sagittal direction. The temporal resolution of 1.1 s per dataset was achieved using the keyhole technique with the reference scan acquired at the end. Immediately after the intravenous (IV) injection of 0.1 mmol Gd/kg body weight of gadoterate, our patients received a 50-mL flush consisting either of a 0.9% saline solution (n = 11) or doped with 50 mM gadolinium (n = 11; total Gd: 0.11 mmol/kg) at a flow-rate of 2 mL/s. Vessel delineation, image quality, signal-to-noise- (SNR) and contrast-to-noise (CNR) ratios over time were compared.

RESULTS

Both vessel delineation (internal carotid artery [ICA]: slope(saline) = 308.5; slope(Gd) = 528.9; P = 0.006; superior sagittal sinus [SSS]: slope(saline) = 505.3; slope(Gd) = 674.9; P = 0.007) and CNR (ICA: CNR(saline) = 57.3; CNR(Gd) = 80.55; P = 0.0417; SSS: CNR(saline) = 74.15; CNR(Gd) = 117.4; P = 0.0331) of the ICA and SSS were significantly increased using the gadolinium doped flush.

CONCLUSION

A low concentrated gadolinium flush in comparison to a pure saline flush improves significantly vessel contrast and their delineation in time-resolved CE-MRA using the keyhole technique.

Magnetic resonance angiography: current status in the planning and follow-up of endovascular treatment in lower-limb arterial disease

Magnetic resonance angiography (MRA) has become an established imaging modality in the management of lower-limb arterial disease, with emerging roles in treatment planning and follow-up. Contrast-enhanced MRA is now the most widely used technique with clinically acceptable results in the majority of patients. Difficulties in imaging and image interpretation are recognised in certain subgroups, including patients with critical limb ischaemia as well as patients with stents. Although newer contrast agents and refined imaging protocols may offer some solutions to these problems, this optimism is balanced by concerns about the toxicity of certain gadolinium chelates. Further development of interventional MRA remains one of the most significant challenges in the development of magnetic resonance imaging-guided peripheral vascular intervention. The status of MRA in managing patients with lower-limb arterial disease in current clinical practice is reviewed.

Extracellular gadolinium-based contrast media: differences in diagnostic efficacy

Since the introduction of the first gadolinium-based contrast agent (Gd-CA) in 1988 it has become clear that these agents significantly improve the diagnostic efficacy of MRI. Studies on single agents have shown that, in comparison to unenhanced sequences, all agents help to improve the detection and delineation of lesions which can alter diagnosis in up to 40% of patients. Doubling or tripling the standard dose of 0.1 mmol/kg body weight may be beneficial for selected indications (e.g. brain perfusion, equivocal single dose study in MRI for brain metastasis, small vessel MR angiography). A more limited number of studies have compared the various agents. These studies do not show clinically significant differences in diagnostic efficacy between the various extracellular Gd-CA. Agents with higher concentration or protein binding may be relatively better suitable for selected applications (e.g. perfusion MRI). The higher relaxivity agents may be used in somewhat lower doses than the extracellular agents.

Magnetic Resonance Angiography in Infrapopliteal Arterial Disease

PURPOSE

To prospectively determine the accuracy of 1.5 Tesla (T) and 3 T magnetic resonance angiography (MRA) versus digital subtraction angiography (DSA) in the depiction of infrageniculate arteries in patients with symptomatic peripheral arterial disease.

PATIENTS AND METHODS

A prospective 1.5 T, 3 T MRA, and DSA comparison was used to evaluate 360 vessel segments in 10 patients (15 limbs) with chronic symptomatic peripheral arterial disease. Selective DSA was performed within 30 days before both MRAs. The accuracy of 1.5 T and 3 T MRA was compared with DSA as the standard of reference by consensus agreement of 2 experienced readers. Signal-to-noise ratios (SNR) and signal-difference-to-noise ratios (SDNRs) were quantified.

RESULTS

No significant difference in overall image quality, sufficiency for diagnosis, depiction of arterial anatomy, motion artifacts, and venous overlap was found comparing 1.5 T with 3 T MRA (P > 0.05 by Wilcoxon signed rank and as by Cohen k test). Overall sensitivity of 1.5 and 3 T MRA for detection of significant arterial stenosis was 79% and 82%, and specificity was 87% and 87% for both modalities, respectively. Interobserver agreement was excellent k > 0.8, P < 0.05) for 1.5 T as well as for 3 T MRA. SNR and SDNR were significantly increased using the 3 T system (average increase: 36.5%, P < 0.032 by t test, and 38.5%, P < 0.037 respectively).

CONCLUSIONS

Despite marked improvement of SDNR, 3 T MRA does not yet provide a significantly higher accuracy in diagnostic imaging of atherosclerotic lesions below the knee joint as compared with 1.5 T MRA.

A multicenter, site-independent, blinded study to compare the diagnostic accuracy of contrast-enhanced magnetic resonance angiography using 1.0M gadobutrol (Gadovist™) to intraarterial digital subtraction angiography in body arteries

PURPOSE

Prospective evaluation of diagnostic accuracy of single field-of-view contrast-enhanced MR Angiography (ceMRA) with 1.0M gadobutrol compared to intraarterial DSA in body arteries.

MATERIALS AND METHODS

In an European multicenter study 179 patients underwent ceMRA and DSA. For each indication five prospectively defined vessel segments were evaluated by local investigators onsite and by three site-independent blinded readers (BR) independently.

RESULTS

The agreement between ceMRA and DSA diagnosis was statistically significant in the onsite (96.6%) and blinded reader (86.6-90.2%) evaluation. Sensitivity, specificity, accuracy, positive (PPV) and negative predictive values (NPV) for detection of relevant stenosis (>50%) were calculated for the right and left internal carotid arteries, and common and external iliac arteries: Sensitivity was 95-98% (onsite) and 76-96% (BR), specificity 94-96% (onsite) and 86-94% (BR), accuracy 96% (onsite) and 87-93% (BR), NPV 98-99% (onsite) and 84-98% (BR), and PPV 79-93% (onsite) and 44-91% (BR), respectively.

CONCLUSION

CeMRA of body arteries using 1.0M gadobutrol provides diagnostic information comparable to intraarterial DSA.

Optimization of spatial resolution for peripheral magnetic resonance angiography

RATIONALE AND OBJECTIVES

To determine optimum spatial resolution when imaging peripheral arteries with magnetic resonance angiography (MRA).

MATERIALS AND METHODS

Eight vessel diameters ranging from 1.0 to 8.0 mm were simulated in a vascular phantom. A total of 40 three-dimensional flash MRA sequences were acquired with incremental variations of fields of view, matrix size, and slice thickness. The accurately known eight diameters were combined pairwise to generate 22 "exact" degrees of stenosis ranging from 42% to 87%. Then, the diameters were measured in the MRA images by three independent observers and with quantitative angiography (QA) software and used to compute the degrees of stenosis corresponding to the 22 "exact" ones. The accuracy and reproducibility of vessel diameter measurements and stenosis calculations were assessed for vessel size ranging from 6 to 8 mm (iliac artery), 4 to 5 mm (femoro-popliteal arteries), and 1 to 3 mm (infrapopliteal arteries). Maximum pixel dimension and slice thickness to obtain a mean error in stenosis evaluation of less than 10% were determined by linear regression analysis.

RESULTS

Mean errors on stenosis quantification were 8.8% +/- 6.3% for 6- to 8-mm vessels, 15.5% +/- 8.2% for 4- to 5-mm vessels, and 18.9% +/- 7.5% for 1- to 3-mm vessels. Mean errors on stenosis calculation were 12.3% +/- 8.2% for observers and 11.4% +/- 15.1% for QA software (P = .0342). To evaluate stenosis with a mean error of less than 10%, maximum pixel surface, the pixel size in the phase direction, and the slice thickness should be less than 1.56 mm2, 1.34 mm, 1.70 mm, respectively (voxel size 2.65 mm3) for 6- to 8-mm vessels; 1.31 mm2, 1.10 mm, 1.34 mm (voxel size 1.76 mm3), for 4- to 5-mm vessels; and 1.17 mm2, 0.90 mm, 0.9 mm (voxel size 1.05 mm3) for 1- to 3-mm vessels.

CONCLUSION

Higher spatial resolution than currently used should be selected for imaging peripheral vessels.

Effects of injection rate and dose on image quality in time-resolved magnetic resonance angiography (MRA) by using 1.0M contrast agents

In time-resolved MRA (TR MRA), injection parameters and contrast agent (CA) dose are important factors influencing image quality. In this study, three different injection schemes with different CA volumes were evaluated in 12 healthy volunteers. Injection rates between 0.2 and 0.8 ml/s were evaluated with CA volumes of 10 and 20 ml. To measure circulatory parameters, cine cardiac MRI was performed before each exam. Spatial resolution could be reduced to 2 x 1.4 x 2 mm3, temporal resolution was 2.25 s/frame. To exclude signal saturation at high CA concentrations, a phantom with fixed CA concentrations was placed in the field of view. SNR was measured, and the area under the curve of the arterial signal of the different injection schemes was calculated. Results showed the largest diagnostic window at a relatively slow injection rate of 0.4 ml/s and a CA volume of 10 ml. Circulatory parameters have an important impact on CA arrival, so delay times have to be set depending on these parameters.

Routine Use of Three-Dimensional Contrast-Enhanced Moving-Table MR Angiography in Patients with Peripheral Arterial Occlusive Disease: Comparison with Selective Digital Subtraction Angiography

PURPOSE

To compare the diagnostic accuracy of contrast-enhanced (CE) three-dimensional (3D) moving-table magnetic resonance (MR) angiography with that of selective digital subtraction angiography (DSA) for routine clinical investigation in patients with peripheral arterial occlusive disease.

METHODS

Thirty-eight patients underwent CE 3D moving-table MR angiography of the pelvic and peripheral arteries. A commercially available large-field-of-view adapter and a dedicated peripheral vascular phased-array coil were used. MR angiograms were evaluated for grade of arterial stenosis, diagnostic quality, and presence of artifacts. MR imaging results for each patient were compared with those of selective DSA.

RESULTS

Two hundred and twenty-six arterial segments in 38 patients were evaluated by both selective DSA and MR angiography. No complications related to MR angiography were observed. There was agreement in stenosis classification in 204 (90.3%) segments; MR angiography overgraded 16 (7%) segments and undergraded 6 (2.7%) segments. Compared with selective DSA, MR angiography provided high sensitivity and specificity and excellent interobserver agreement for detection of severe stenosis (97% and 95%, kappa = 0.9 +/- 0.03) and moderate stenosis (96.5% and 94.3%, kappa = 0.9 +/- 0.03).

CONCLUSION

Compared with selective DSA, moving-table MR angiography proved to be an accurate, noninvasive method for evaluation of peripheral arterial occlusive disease and may thus serve as an alternative to DSA in clinical routine.

Magnetic resonance angiography of abdominal and lower extremity vasculature

Magnetic resonance angiography (MRA) has evolved over the past years from an experimental imaging modality to a technique that is now widely applied in clinical practice. This article reviews the fundamentals of the different magnetic resonance angiographic techniques and how they can be applied for abdominal and peripheral arterial imaging. Currently, contrast-enhanced magnetic resonance angiography (CE-MRA), whereby a luminogram is obtained during initial arterial passage of contrast material, is the most widely used technique. With current hardware and software, high-spatial resolution images of the abdominal aorta and proximal visceral branches can be obtained that are equivalent to intra-arterial digital subtraction angiography (IA-DSA). High-quality imaging of the renal arteries demands isotropic voxels and reformations orthogonal to the vessel axis for evaluation. Contrast-enhanced magnetic resonance angiography of the peripheral vascular tree is now a highly accurate technique and has replaced diagnostic intra-arterial digital subtraction angiography and duplex ultrasonography in many hospitals.

Gadolinium-enhanced Magnetic Resonance Angiography, Colour Duplex and Digital Subtraction Angiography of the Lower Limb Arteries from the Aorta to the Tibio-peroneal Trunk in Patients with Intermittent Claudication

OBJECTIVES

To evaluate the sensitivity, specificity, positive and negative predictive value of contrast-enhanced (gadolinium) magnetic resonance imaging (CE-MRA) and colour duplex ultrasound (CDU) of lower limb arteries.

DESIGN

Prospective, single centre study.

MATERIAL AND METHODS

A consecutive series of 58 patients with intermittent claudication (IC) were examined with CE-MRA and CDU from the infrarenal aorta to the tibio-peroneal trunk with digital subtraction angiography (DSA) as reference. The arterial tree was divided into 15 segments, pooled into three regions; suprainguinal, thigh and knee. Sensitivity, specificity, positive and negative predictive values for significant obstructions were calculated. Cohen Kappa statistics was used to establish agreement between the three methods.

RESULTS

The sensitivity (specificity in parentheses) for significant obstructions in the suprainguinal region were 96% (94%) for CE-MRA and 91% (96%) for CDU, in the thigh region 92% (95%) for CE-MRA and 76% (99%) for CDU, and in the knee region 93% (96%) for CE-MRA and 33% (98%) for CDU. CDU failed to visualize 10% of suprainguinal, 2% of thigh and 13% of knee-region arterial segments.

CONCLUSIONS

Both CE-MRA and CDU are good alternatives to DSA in the suprainguinal- and thigh-region. In the knee region only CE-MRA can be relied upon as an alternative to DSA. Imaging by CDU is not suited to situations were evaluation of runoff vessels is important.

Quantitative Vascular Measurements in Arterial Occlusive Disease

Accuracy in quantifying arterial occlusive disease requires an understanding of the relevant technical considerations and familiarity with the strengths and weaknesses of various imaging modalities in this setting. The degree of stenosis is evaluated in terms of diameter stenosis, which can be measured on either projection images or cross-sectional images, or area stenosis, which can be measured only on cross-sectional images. With projection images, the minimum luminal diameter should be sought on multiple images obtained at different angles. The reference site used for measurement should be noted and may be located at the level of the lesion or in a normal-looking portion of the stenotic vessel near the lesion. Multi-detector row computed tomographic (CT) angiography and magnetic resonance (MR) angiography are starting to replace digital subtraction angiography in quantifying arterial occlusive disease. CT angiography allows accurate evaluation without reducing in-plane resolution, although beam-hardening artifacts from high-attenuation structures can degrade image quality. MR angiography is useful even in cases of severe calcification but has a lower spatial resolution. Ultrasonography (US) may also be helpful in quantifying arterial occlusive disease; US analysis is almost always based on blood flow velocity measurement. Precise measurements of stenotic occlusion will help determine optimal therapy for affected patients.

Interference of Gadolinium-Containing Contrast-Enhancing Agents With Colorimetric Calcium Laboratory Testing

OBJECTIVES

The purpose of this study was to evaluate the extent to which various commercially available gadolinium-containing contrast-enhancing (CE) agents can interfere with the measurement of calcium levels by currently used laboratory methods, suggesting (spurious) hypocalcemia or hypercalcemia with a potential risk for the patient.

MATERIALS AND METHODS

Serum and plasma from healthy volunteers were spiked with various concentrations of 4 marketed CE agents. The calcium concentration was measured by widely used laboratory methods: the colorimetric systems Cobas Mira and Vitros 950 analyzer.

RESULTS

The measurement of calcium in serum and in plasma was not affected by the presence of gadopentetate dimeglumine (Magnevist, Schering AG, Berlin, Germany) or gadobenate dimeglumine (MultiHance, Bracco-Byk Gulden, Constance, Switzerland) in clinically relevant concentrations (up to 5 mM CE agent). Gadodiamide (Omniscan, Amersham Health, Cork, Ireland) and gadoversetamide (OptiMARK, Mallinckrodt, St. Louis, MO) did produce noticeable-and therefore potentially misleading-effects at these concentrations.

CONCLUSIONS

The study demonstrates that gadopentetate dimeglumine and gadobenate dimeglumine generate no interference with colorimetric methods for calcium determination, whereas strong interference was shown for gadodiamide and gadoversetamide under clinically relevant conditions.

Normal Anterior Spinal Arteries within the Cervical Region: High-Spatial-Resolution Contrast-enhanced Three-dimensional MR Angiography

PURPOSE

To determine retrospectively whether the anterior spinal artery (ASA) is visualized in the cervical region with contrast material-enhanced high-spatial-resolution three-dimensional magnetic resonance (MR) angiography of the extracranial carotid and vertebral arteries.

MATERIALS AND METHODS

The institutional research ethics committee approved this study and provided a waiver for informed consent. Data sets were evaluated in 50 consecutive patients referred for contrast-enhanced three-dimensional MR angiography of the carotid arteries (32 male and 18 female patients; age range, 15-80 years; mean age, 59 years). The ASA was defined as a linear area of high signal intensity that is seen anterior to the spinal cord in an arterial phase of enhancement and connects directly to a known arterial structure. If the linear area of high signal intensity was seen in the arterial phase but did not connect to a known arterial structure, it was considered a probable ASA. Venous enhancement was graded on a five-point scale (0-4) with grade 0 (no venous enhancement) or grade 1 (trace venous enhancement) considered to be in the arterial phase.

RESULTS

The ASA was identified with certainty in 37 of 50 patients. A vessel visualized anterior to the spinal cord, which probably represented the ASA, was seen in another 11 of 50 patients. In 29 of 50 patients the vessel was visualized only on the full-volume maximum intensity projection (MIP) image. In the remainder of cases the artery was identified on operator-defined subvolume MIP images. Continuity between the vessel and the vertebrobasilar arterial structures was identified in 35 of 50 patients. The vessel was seen as a continuous structure throughout its length in 34 patients and appeared discontinuous in 14. Radiculomedullary feeders were identified in 24 of 50 patients.

CONCLUSION

The normal cervical ASA was visualized in 48 of 50 of subjects with contrast-enhanced high-spatial-resolution three-dimensional MR angiography.

Comprehensive MR angiography of the lower limbs: a hybrid dual-bolus approach including the pedal arteries

The purpose of this study was to include the pedal vasculature into the coverage of peripheral multistation magnetic resonance angiography (3DceMRA). A total of 216 patients suffering from peripheral vascular disease were examined with a modified hybrid dual-bolus technique. The cruropedal arteries were acquired first with two sagittal slabs and time-resolved 3D sequences. Then the aortofemoral vessels were visualized using the bolus-chase technique and a second contrast injection. Interventional procedures were performed in 104 patients, and in 69 of those, the cruropedal vessels were also examined with digital subtraction angiography (iaDSA). Using 3DceMRA, the cruropedal arteries were displayed with both excellent and good quality in 95% (205/216 cases), and without any venous overlay in 94% (203/216 cases). The aortofemoral vessels were not jeopardized by the first contrast injection. With iaDSA as the standard of reference, observed sensitivity of 3DceMRA was found in ranges from 80% (29%, 99%) to 100% (86%, 100%) for assessing significant stenoses, and observed specificity ranged between 93% [80%, 98%] and 100% (82%, 100%). In conclusion, hybrid dual-bolus 3DceMRA significantly reduces the limitations of standard single-bolus 3DceMRA in anatomic coverage and temporal resolution of the cruropedal arteries, thus providing high-quality images of the entire peripheral vasculature.

Preliminary experience with contrast-enhanced MR angiography in patients with end-stage renal failure

RATIONALE AND OBJECTIVES

The purpose of this study was to evaluate our preliminary experience with routine contrast-enhanced magnetic resonance angiography (CE-MRA) of the lower limb arteries in patients with end-stage renal failure.

MATERIALS AND METHODS

A retrospective analysis was performed on clinical, physiological, and imaging data for 104 patients with end-stage renal failure. Patients were considered to be in end-stage renal failure if they were on renal replacement therapy (peritoneal or hemodialysis) or were being evaluated as part of a pretransplant workup. CE-MRA was carried out on a 1.5-T scanner using a single-injection, three-station moving table technique.

RESULTS

Eleven percent of asymptomatic patients with normal ankle/brachial pressure indexes (ABPI) were found to have severe arterial disease on CE-MRA, and in 30% of asymptomatic patients with abnormal ABPI, CE-MRA showed mild or no disease. Moreover two of three symptomatic patients with normal ABPI were shown to have severe disease. Two patients on peritoneal dialysis had to be switched to hemodialysis. No other adverse events were revealed.

CONCLUSION

CE-MRA is a useful adjunct to clinical and physiological examination for the evaluation of the lower limb arteries in a group of patients who have a higher-than-average incidence of peripheral vascular disease, yet have previously been severely restricted from traditional angiography because of contrast-medium-induced nephrotoxicity.