Prospective intraindividual comparison of gadoterate and gadobutrol for cervical and intracranial contrast-enhanced magnetic resonance angiography

Evolving Characteristics of Gadolinium-Based Contrast Agents for MR Imaging: A Systematic Review of the Importance of Relaxivity

Gadolinium-based contrast agents (GBCAs) are widely and routinely used to enhance the diagnostic performance of magnetic resonance imaging and magnetic resonance angiography examinations. T1 relaxivity (r1) is the measure of their ability to increase signal intensity in tissues and blood on T1-weighted images at a given dose. Pharmaceutical companies have invested in the design and development of GBCAs with higher and higher T1 relaxivity values, and "high relaxivity" is a claim frequently used to promote GBCAs, with no clear definition of what "high relaxivity" means, or general concurrence about its clinical benefit. To understand whether higher relaxivity values translate into a material clinical benefit, well-designed, and properly powered clinical studies are necessary, while mere in vitro measurements may be misleading. This systematic review of relevant peer-reviewed literature provides high-quality clinical evidence showing that a difference in relaxivity of at least 40% between two GBCAs results in superior diagnostic efficacy for the higher-relaxivity agent when this is used at the same equimolar gadolinium dose as the lower-relaxivity agent, or similar imaging performance when used at a lower dose. Either outcome clearly implies a relevant clinical benefit. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 3.

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.

All answers are in the images: A review of deep learning for cerebrovascular segmentation

Cerebrovascular imaging is a common examination. Its accurate cerebrovascular segmentation become an important auxiliary method for the diagnosis and treatment of cerebrovascular diseases, which has received extensive attention from researchers. Deep learning is a heuristic method that encourages researchers to derive answers from the images by driving datasets. With the continuous development of datasets and deep learning theory, it has achieved important success for cerebrovascular segmentation. Detailed survey is an important reference for researchers. To comprehensively analyze the newest cerebrovascular segmentation, we have organized and discussed researches centered on deep learning. This survey comprehensively reviews deep learning for cerebrovascular segmentation since 2015, it mainly includes sliding window based models, U-Net based models, other CNNs based models, small-sample based models, semi-supervised or unsupervised models, fusion based models, Transformer based models, and graphics based models. We organize the structures, improvement, and important parameters of these models, as well as analyze development trends and quantitative assessment. Finally, we have discussed the challenges and opportunities of possible research directions, hoping that our survey can provide researchers with convenient reference.

MRA of the Supraaortic Vasculature: Comparison of Gadobutrol and Gadoterate Meglumine at 1.5 T

BACKGROUND

Gadobutrol (GB) and gadoterate meglumine (GM) are contrast agents used for contrast-enhanced magnetic resonance angiography (CEMRA). Supraaortic vasculature (SAV) CEMRAs are used to evaluate stroke risk and neurologic symptoms. There is a need to compare the SAV CEMRA image quality obtained with GB and GM.

PURPOSE

To intra-individually compare MRA images obtained with equimolar GB and GM at 1.5 T in the SAV.

STUDY TYPE

Prospective, crossover.

POPULATION

Twenty-eight subjects (54 ± 13 years; 17 female).

FIELD STRENGTH/SEQUENCE

1.5 T; three-dimensional (3D) gradient recalled echo.

ASSESSMENT

Quantitative image quality was measured by normalized signal intensity (SI_n ) [SI_n  = SI blood/SD blood] and contrast ratio (CR) [CR = SI blood/SI muscle], determined by an observer (JWC) with 1 year of vascular imaging experience. Three radiologists (AS, PA, and MU) with (5, 5, and 6 years of) vascular imaging experience evaluated image quality by Likert-scale ratings (of image impression, wall conspicuity, and artifact absence).

STATISTICAL TESTS

SI_n and CR were compared with paired t-tests or Wilcoxon signed-rank tests and Bland-Altman plots. Qualitative ratings were compared with Wilcoxon signed-rank test.

RESULTS

No significant difference in SI_n was found between GB and GM. CRs with GB were significantly higher than GM at the right common carotid (6.9 ± 2.5 vs. 4.8 ± 1), left internal carotid (7.3 ± 2 vs. 4.4 ± 1.2), right internal carotid (7.7 ± 2.2 vs. 5 ± 1.1), and left vertebral (6.6 ± 2.2 vs. 4.5 ± 1.1) arteries. Bland-Altman plots showed relatively greater differences between GB and GM at higher CRs and SI_n s. GM showed significantly higher artifact than GB (3.56 ± 0.52 vs. 3.36 ± 0.46) and significantly lower overall image quality (10.73 ± 1.45 vs. 11.26 ± 1.58) at the left vertebral artery.

DATA CONCLUSION

At 1.5 T and equimolar demonstration, GB (0.1 mL/kg, i.e., 0.1 mmol/kg) showed higher CRs in the SAV compared to GM (0.2 mL/kg, i.e., 0.1 mmol/kg) at most vessels. Subjective image quality was not significantly different between the two agents for most vessels.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 2.

Non-contrast mDixon MR angiography of the neck: Comparison with time-of-flight MR angiography in normal subjects

We investigated the feasibility of non-contrast three-dimensional modified Dixon (mDixon) magnetic resonance angiography (MRA) to evaluate the carotid artery.We studied 30 normal patients who underwent non-contrast mDixon and conventional time-of-flight (TOF) MRA of the neck with a clinical 3T MR scanner. Carotid artery signal-to-noise ratio (SNR) and contrast-to-noise ratio were compared between mDixon-MRA and TOF-MRA. Two readers independently evaluated vessel sharpness, image contrast, and overall image quality using a 4-point scale.SNR was significantly higher on mDixon-MRA than TOF-MRA (P < .01). There was no significant difference in contrast-to-noise ratio. The visual score for vessel sharpness was significantly higher on mDixon-MRA than TOF-MRA (P < .01), whereas the score for contrast was significantly higher on TOF-MRA (P < .01).Although non-contrast three-dimensional mDixon-MRA showed lower visual contrast than conventional TOF-MRA, it provided images with significantly higher SNR and better vessel sharpness than TOF-MRA.

Dynamic contrast-enhanced MR imaging of the prostate: intraindividual comparison of gadoterate meglumine and gadobutrol

OBJECTIVES

To intraindividually compare the signal-enhancing effect of 0.5 M gadoterate meglumine and 1.0 M gadobutrol in dynamic contrast-enhanced magnetic resonance (DCE-MR) imaging of the prostate.

METHODS

Fifty patients who underwent two 3-T MR examinations of the prostate were included in this IRB-approved retrospective uncontrolled, unrandomized study. All received two scans (mean time interval, 20.5 months) including T1-weighted DCE-MR imaging, one with 0.5 M gadoterate meglumine and one with 1.0 M gadobutrol. Equimolar doses of gadolinium (0.1 mmol/kg body weight) were administered with identical injection speed (2 mL/s), resulting in differing gadolinium delivery rate. An identical region of interest (ROI_tz) within a BPH-node was identified on both scans. The area under the time-enhancement curve of each ROI_tz from 0 to 180 s post contrast arrival and pharmacokinetic parameters were calculated. Relative enhancement and signal-to-noise (SNR) and contrast-to-noise (CNR) ratios in the delayed phase at about 180 s were compared between both agents.

RESULTS

There was a significantly larger area under the time-enhancement curve (5.53 vs 4.97 p = 0.0007) and higher relative enhancement of BPH nodules (2.23 vs 1.96 p < 0.0001) with gadobutrol compared with gadoterate meglumine. There were no significant differences in SNR (44.55 vs 37.63 p = 0.12), CNR (31.22 vs 26.39 p = 0.18), and pharmacokinetic parameters Ktrans (0.31 vs 0.32 p = 0.86), Ve (1.36 vs 0.98 p = 0.13), and Kep (0.34 vs 0.36 p = 0.12).

CONCLUSIONS

At equimolar doses, increased gadolinium delivery over time using gadobutrol provides higher relative enhancement parameters in BPH nodules compared with gadoterate meglumine, but does not translate into improved SNR or CNR.

KEY POINTS

• At equal injection rate and equimolar total dose, gadobutrol compared with gadoterate meglumine provides a significantly greater relative enhancement in DCE-MR imaging of BPH over the first 180 s. • There are no significant differences in SNRs, CNRs, and pharmacokinetic parameters between the two GBCAs.

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.