Breast Lesion Detection and Characterization at Contrast-enhanced MR Mammography: Gadobenate Dimeglumine versus Gadopentetate Dimeglumine

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.

Screening Breast MRI and Gadolinium Deposition: Cause for Concern?

Gadolinium-based contrast agents (GBCAs) have been used worldwide for over 30 years and have enabled lifesaving diagnoses. Contrast-enhanced breast MRI is frequently used as supplemental screening for women with an elevated lifetime risk of breast cancer. Data have emerged that indicate a fractional amount of administered gadolinium is retained in the bone, skin, solid organs, and brain tissues of patients with normal renal function, although there are currently no reliable data regarding the clinical or biological significance of this retention. Linear GBCAs are associated with a higher risk of gadolinium retention than macrocyclic agents. Over the course of their lives, screened women may receive high cumulative doses of GBCA. Therefore, as breast MRI screening utilization increases, thoughtful use of GBCA is indicated in this patient population.

Automatic Detection and Segmentation of Breast Cancer on MRI Using Mask R-CNN Trained on Non-Fat-Sat Images and Tested on Fat-Sat Images

RATIONALE AND OBJECTIVES

Computer-aided methods have been widely applied to diagnose lesions on breast magnetic resonance imaging (MRI). The first step was to identify abnormal areas. A deep learning Mask Regional Convolutional Neural Network (R-CNN) was implemented to search the entire set of images and detect suspicious lesions.

MATERIALS AND METHODS

Two DCE-MRI datasets were used, 241 patients acquired using non-fat-sat sequence for training, and 98 patients acquired using fat-sat sequence for testing. All patients have confirmed unilateral mass cancers. The tumor was segmented using fuzzy c-means clustering algorithm to serve as the ground truth. Mask R-CNN was implemented with ResNet-101 as the backbone. The neural network output the bounding boxes and the segmented tumor for evaluation using the Dice Similarity Coefficient (DSC). The detection performance, and the trade-off between sensitivity and specificity, was analyzed using free response receiver operating characteristic.

RESULTS

When the precontrast and subtraction image of both breasts were used as input, the false positive from the heart and normal parenchymal enhancements could be minimized. The training set had 1469 positive slices (containing lesion) and 9135 negative slices. In 10-fold cross-validation, the mean accuracy = 0.86 and DSC = 0.82. The testing dataset had 1568 positive and 7264 negative slices, with accuracy = 0.75 and DSC = 0.79. When the obtained per-slice results were combined, 240 of 241 (99.5%) lesions in the training and 98 of 98 (100%) lesions in the testing datasets were identified.

CONCLUSION

Deep learning using Mask R-CNN provided a feasible method to search breast MRI, localize, and segment lesions. This may be integrated with other artificial intelligence algorithms to develop a fully automatic breast MRI diagnostic system.

Breast lesion detection and characterization with contrast-enhanced magnetic resonance imaging: Prospective randomized intraindividual comparison of gadoterate meglumine (0.15 mmol/kg) and gadobenate dimeglumine (0.075 mmol/kg) at 3T

Background

Contrast‐enhanced magnetic resonance imaging (CE‐MRI) of the breast is highly sensitive for breast cancer detection. Multichannel coils and 3T scanners can increase signal, spatial, and temporal resolution. In addition, the T₁‐reduction effect of a gadolinium‐based contrast agent (GBCA) is higher at 3T. Thus, it might be possible to reduce the dose of GBCA at 3T without losing diagnostic information.

Purpose

To compare a three‐quarter (0.075 mmol/kg) dose of the high‐relaxivity GBCA gadobenate dimeglumine, with a 1.5‐fold higher than on‐label dose (0.15 mmol/kg) of gadoterate meglumine for breast lesion detection and characterization at 3T CE‐MRI.

Study Type

Prospective, randomized, intraindividual comparative study.

Population

Eligible were patients with imaging abnormalities (BI‐RADS 0, 4, 5) on conventional imaging. Each patient underwent two examinations, 24–72 hours apart, one with 0.075 mmol/kg gadobenate and the other with 0.15 mmol/kg gadoterate administered in a randomized order. In all, 109 patients were prospectively recruited.

Field Strength/Sequence

3T MRI with a standard breast protocol (dynamic‐CE, T₂w‐TSE, STIR‐T₂w, DWI).

Assessment

Histopathology was the standard of reference. Three blinded, off‐site breast radiologists evaluated the examinations using the BI‐RADS lexicon.

Statistical Tests

Lesion detection, sensitivity, specificity, and diagnostic accuracy were calculated per‐lesion and per‐region, and compared by univariate and multivariate analysis (Generalized Estimating Equations, GEE).

Results

Five patients were excluded, leaving 104 women with 142 histologically verified breast lesions (109 malignant, 33 benign) available for evaluation. Lesion detection with gadobenate (84.5‐88.7%) was not inferior to gadoterate (84.5–90.8%) (P ≥ 0.165). At per‐region analysis, gadobenate demonstrated higher specificity (96.4–98.7% vs. 92.6–97.3%, P ≤ 0.007) and accuracy (96.3–97.8% vs. 93.6–96.1%, P ≤ 0.001) compared with gadoterate. Multivariate analysis demonstrated superior, reader‐independent diagnostic accuracy with gadobenate (odds ratio = 1.7, P < 0.001 using GEE).

Data Conclusion

A 0.075 mmol/kg dose of the high‐relaxivity contrast agent gadobenate was not inferior to a 0.15 mmol/kg dose of gadoterate for breast lesion detection. Gadobenate allowed increased specificity and accuracy.

Level of Evidence: 1

Technical Efficacy: Stage 2

J. Magn. Reson. Imaging 2019;49:1157–1165.

Ultrafast dynamic contrast-enhanced mri of the breast using compressed sensing: breast cancer diagnosis based on separate visualization of breast arteries and veins

PURPOSE

To evaluate the feasibility of ultrafast dynamic contrast-enhanced (UF-DCE) magnetic resonance imaging (MRI) with compressed sensing (CS) for the separate identification of breast arteries/veins and perform temporal evaluations of breast arteries and veins with a focus on the association with ipsilateral cancers.

MATERIALS AND METHODS

Our Institutional Review Board approved this study with retrospective design. Twenty-five female patients who underwent UF-DCE MRI at 3T were included. UF-DCE MRI consisting of 20 continuous frames was acquired using a prototype 3D gradient-echo volumetric interpolated breath-hold sequence including a CS reconstruction: temporal resolution, 3.65 sec/frame; spatial resolution, 0.9 × 1.3 × 2.5 mm. Two readers analyzed 19 maximum intensity projection images reconstructed from subtracted images, separately identified breast arteries/veins and the earliest frame in which they were respectively visualized, and calculated the time interval between arterial and venous visualization (A-V interval) for each breast.

RESULTS

In total, 49 breasts including 31 lesions (breast cancer, 16; benign lesion, 15) were identified. In 39 of the 49 breasts (breasts with cancers, 16; breasts with benign lesions, 10; breasts with no lesions, 13), both breast arteries and veins were separately identified. The A-V intervals for breasts with cancers were significantly shorter than those for breasts with benign lesions (P = 0.043) and no lesions (P = 0.007).

CONCLUSION

UF-DCE MRI using CS enables the separate identification of breast arteries/veins. Temporal evaluations calculating the time interval between arterial and venous visualization might be helpful in the differentiation of ipsilateral breast cancers from benign lesions.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:97-104.

Potential of Diffusion-Weighted Imaging in the Characterization of Malignant, Benign, and Healthy Breast Tissues and Molecular Subtypes of Breast Cancer

The role of apparent diffusion coefficient (ADC) in the diagnosis of breast cancer and its association with molecular biomarkers was investigated in 259 patients with breast cancer, 67 with benign pathology, and 54 healthy volunteers using diffusion-weighted imaging (DWI) at 1.5 T. In 59 breast cancer patients, dynamic contrast-enhanced MRI (DCEMRI) was also acquired. Mean ADC of malignant lesions was significantly lower (1.02 ± 0.17 × 10⁻³ mm²/s) compared to benign (1.57 ± 0.26 × 10⁻³ mm²/s) and healthy (1.78 ± 0.13 × 10⁻³ mm²/s) breast tissues. A cutoff ADC value of 1.23 × 10⁻³ mm²/s (sensitivity 92.5%; specificity 91.1%; area under the curve 0.96) to differentiate malignant from benign diseases was arrived by receiver operating curve analysis. In 10/59 breast cancer patients, indeterminate DCE curve was seen, while their ADC value was indicative of malignancy, implying the potential of the addition of DWI in increasing the specificity of DCEMRI data. Further, the association of ADC with tumor volume, stage, hormonal receptors [estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor (HER2)], and menopausal status was investigated. A significant difference was seen in tumor volume between breast cancer patients of stages IIA and IIIA, IIB and IIIA, and IIB and III (B + C), respectively (P < 0.05). Patients with early breast cancer (n = 52) had significantly lower ADC and tumor volume than those with locally advanced breast cancer (n = 207). No association was found in ADC and tumor volume with the menopausal status. Breast cancers with ER−, PR−, and triple-negative (TN) status showed a significantly larger tumor volume compared to ER+, PR+, and non-triple-negative (nTN) cancers, respectively. Also, TN tumors showed a significantly higher ADC compared to ER+, PR+, and nTN cancers. Patients with ER− and TN cancers were younger than those with ER+ and nTN cancers. The present study demonstrated that ADC may increase the diagnostic specificity of DCEMRI and be useful for treatment management in clinical setting. Additionally, it provides an insight into characterization of molecular types of breast cancer and may serve as an indicator of metabolic reprograming underlying tumor proliferation.

Supine breast US: how to correlate breast lesions from prone MRI

OBJECTIVE

To evaluate spatial displacement of breast lesions from prone MR to supine ultrasound positions, and to determine whether the degree of displacement may be associated with breast density and lesion histotype.

METHODS

380 patients underwent breast MR and second-look ultrasound. The MR and ultrasound lesion location within the breast gland, distances from anatomical landmarks (nipple, skin and pectoral muscle), spatial displacement (distance differences from the landmarks within the same breast region) and region displacement (breast region change) were prospectively evaluated. Differences between MR and ultrasound measurements, association between the degree of spatial displacement and both breast density and lesion histotypes were calculated.

RESULTS

In 290/380 (76%) patients, 300 MR lesions were detected. 285/300 (95%) lesions were recognized on ultrasound. By comparing MR and ultrasound, spatial displacement occurred in 183/285 (64.3%) cases while region displacement in 102/285 (35.7%) cases with a circumferential movement along an arc centred on the nipple, having supine ultrasound as the reference standard. A significant association between the degree of lesion displacement and breast density was found (p < 0.00001) with a significant higher displacement in case of fatty breasts. No significant association between the degree of displacement and lesion histotype was found (p = 0.1).

CONCLUSION

Lesion spatial displacement from MRI to ultrasound may occur especially in adipose breasts. Lesion-nipple distance and circumferential displacement from the nipple need to be considered for ultrasound lesion detection.

ADVANCES IN KNOWLEDGE

Second-look ultrasound breast lesion detection could be improved by calculating the lesion-nipple distance and considering that spatial displacement from MRI occurs with a circumferential movement along an arc centred on the nipple.

The Efficacy of One Molar Contrast Material in the Evaluation of Breast Lesions with MR Imaging

BACKGROUND

To investigate the efficacy of 1 molar (containing 1 mol/mL gadobutrol) contrast material in the differentiation of malignant and benign breast lesions with MRI.

MATERIAL/METHODS

Thirty-seven women (age range: 22-77 years, mean: 43.7 years) with 76 breast lesions were included in this study. Dynamic post-contrast images with 0.2 mL/kg gadobutrol (Gadovist) injection were obtained in all patients. Contrast-to-noise-ratio (CNR) of the lesions, as well as their contrast enhancement patterns (ring, heterogeneous, homogenous), and perilesional increased vascularity were studied.

RESULTS

Fifty-six benign and 20 malignant lesions were examined histopathologically. In malignant cases, heterogeneous and peripheral enhancements were most commonly determined, whereas homogeneous enhancement was most commonly determined in benign cases. CNR was 450% in malignant lesions, and 60% in benign lesions.

CONCLUSIONS

Type II/III contrast-time curves, ring/heterogeneous enhancement, prominent increase in CNR, and perilesional vascularity increase are important findings determining malignancy, whereas Type I curves, homogenous enhancement, a slight increase in CNR, and absence of perilesional vascularity increase support findings of benign breast lesions. By increasing CNR and providing increased perilesional vascularity, Gadovist can help in the determination of malignant breast lesions.

Low-dose gadobenate dimeglumine-enhanced MRI of the kidney for the differential diagnosis of localized renal lesions

Objective

To evaluate low-dose gadobenate dimeglumine-enhanced MRI for the differential diagnosis of malignant renal tumors.

Methods

Sixty-two consecutive patients with unclear diagnosis at MDCT/ultrasound underwent dynamic CE-MRI of the kidneys with 0.05 mmol/kg gadobenate dimeglumine. Retrospective image evaluation was performed by two blinded readers. Lesion diagnosis at CE-MRI was correlated with findings from histology following tumor resection or from imaging follow-up after at least 1 year. Assessments were performed of diagnostic quality and level of diagnostic information.

Results

Thirty-nine (63 %) patients were correctly diagnosed with malignant lesions (36 with RCC, 2 with renal metastases, 1 with lymphoma) while 14 (22.6 %) patients were correctly diagnosed with benign (n = 12) or no (n = 2) lesions. Eight patients were considered false positive (5 with oncocytoma, 3 with atypical AML) and 1 patient false negative (atypical RCC). The sensitivity, specificity, accuracy, PPV, and NPV for the diagnosis of malignant renal lesions were 97.5 % (39/40), 63.6 % (14/22), 85.5 % (53/62), 83.0 % (39/47), and 93.3 % (14/15), respectively. Images were excellent in 60 and good in 2 patients. Minimal artifacts that did not compromise diagnosis were noted in 4/62 patients.

Conclusion

Low-dose gadobenate dimeglumine-enhanced MRI is effective for the differential diagnosis of malignant renal tumors.

Compensatory biliary and urinary excretion of gadobenate ion after administration of gadobenate dimeglumine (MultiHance(®)) in cases of impaired hepatic or renal function: a mechanism that may aid in the prevention of nephrogenic systemic fibrosis?

Objective:

To determine whether increased elimination of gadobenate ion via the hepatobiliary pathway might compensate for reduced/absent elimination via the urinary pathway in the event of compromised renal function, as a possible protective mechanism against nephrogenic systemic fibrosis (NSF).

Methods:

15 male Crl:CD^® R(SD)Br rats (Charles River Italia, Como, Italy) randomized to three treatment groups: (1) animals with occluded bile ducts, (2) animals with occluded renal vessels and (3) control animals, each received 0.25 mmol kg⁻¹ of bodyweight of gadobenate dimeglumine (MultiHance^®; Bracco Imaging SpA, Milan, Italy). Urine and bile were collected from 0−30, 30−60, 60−120, 120−240 and 240−480 min after gadobenate dimeglumine administration prior to exsanguination. Determinations of gadobenate ion in blood, bile and urine were performed by high-performance liquid chromatography. Gadolinium (Gd³⁺) levels in excised liver and kidneys were determined by X-ray fluorescence.

Results:

The recovery of gadobenate ion in the urine of rats with bile duct occlusion was significantly higher than that in the urine of normal rats (89.1 ± 4.2% vs 60.6 ± 2.8%; p < 0.0001). Conversely, mean recovery in the bile of rats with renal vessel occlusion was significantly higher than that in the bile of normal rats (96.16 ± 0.55% vs 33.5 ± 4.7%; p < 0.0001). Gadobenate ion was not quantifiable in any group 8 h post-injection.

Conclusion:

Compensatory elimination may be an effective means to overcome compromised renal or hepatobiliary elimination.

Advances in knowledge:

The absence of NSF in at-risk patients administered with gadobenate dimeglumine may in part reflect greater Gd³⁺ elimination via the hepatobiliary route.

Intraindividual, randomized comparison of the macrocyclic contrast agents gadobutrol and gadoterate meglumine in breast magnetic resonance imaging

OBJECTIVES

To compare intraindividually two macrocyclic contrast agents - gadobutrol and gadoterate meglumine (Gd-DOTA) - for dynamic and quantitative assessment of relative enhancement (RE) in benign and malignant breast lesions.

METHODS

This was an ethically approved, prospective, single-centre, randomized, crossover study in 52 women with suspected breast lesions referred for magnetic resonance imaging (MRI). Each patient underwent one examination with gadobutrol and one with Gd-DOTA (0.1 mmol/kg BW) on a 1.5 T system 1 - 7 days apart. Dynamic, T1-weighted, 3D gradient echo sequences were acquired under identical conditions. Quantitative evaluation with at least three regions of interest (ROI) per lesion was performed. Primary endpoint was RE during the initial postcontrast phase after the first and second dynamic acquisition, and peak RE. All lesions were histologically proven; differences between the examinations were evaluated.

RESULTS

Forty-five patients with a total of 11 benign and 34 malignant lesions were assessed. Mean RE was significantly higher for gadobutrol than Gd-DOTA (p < 0.0001). Gadobutrol showed significantly less washout (64.4 %) than Gd-DOTA (75.4 %) in malignant lesions (p = 0.048) CONCLUSIONS: Gadobutrol has higher RE values compared with Gd-DOTA, whereas Gd-DOTA shows more marked washout in malignant lesions. This might improve the detection of breast lesions and influence the specificity of breast MRI-imaging.

Pharmacokinetics of gadobenate dimeglumine in children 2 to 5 years of age undergoing MRI of the central nervous system

PURPOSE

To determine the pharmacokinetic profile of gadobenate dimeglumine in children aged between 2 and 5 years.

MATERIALS AND METHODS

Fifteen children scheduled to undergo contrast-enhanced MRI for suspected disease of the central nervous system received a single intravenous injection of 0.1 mmol/kg gadobenate dimeglumine. Children were stratified into three age groups: 2 to <3 years, 3 to <4 years, and 4 to 5 (i.e., <6 years). Serial blood and urine samples collected at prespecified time-points before and after contrast administration were analyzed for gadolinium concentrations. Pharmacokinetic parameters were calculated using noncompartmental and compartmental techniques.

RESULTS

Mean values of 65.7 μg/mL for highest blood gadolinium concentration, 0.2 L/h/kg for blood clearance, 0.32 L/kg for steady-state volume of distribution, and 1.2 h for terminal elimination half-life were determined across all age groups combined. On average, more than 80% of the dose was eliminated in the urine during the first 24 h after administration. All pharmacokinetic parameters were similar between age groups and no effects of gender were noted. No adverse events considered related to gadobenate dimeglumine administration were reported.

CONCLUSION

In terms of pharmacokinetic profile no dosage adjustment from the approved adult gadobenate dimeglumine dose of 0.1 mmol/kg bodyweight is necessary in children aged between 2 and 5 years.

Use of contrast agents in oncological imaging: magnetic resonance imaging

Magnetic resonance plays a leading role in the management of oncology patients, providing superior contrast resolution and greater sensitivity compared with other techniques, which enables more accurate tumor identification, characterization and staging. Contrast agents are widely used in clinical magnetic resonance imaging; approximately 40-50% of clinical scans are contrast enhanced. Most contrast agents are based on the paramagnetic gadolinium ion Gd3+, which is chelated to avoid the toxic effects of free gadolinium. Multiple factors such as molecule structure, molecule concentration, dose, field strength and temperature determine the longitudinal and transverse relaxation rates (R1 and R2, respectively) and thus the T1- and T2-relaxivities of these chelates. These T1- and T2-relaxivities, together with their pharmacokinetic properties (i.e. distribution and concentration in the area of interest), determine the radiologic efficacy of the gadolinium-based contrast agents.

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.

Gadobenate dimeglumine (MultiHance) in MR angiography: an in-vitro phantom comparison with gadopentetate dimeglumine (Magnevist) at different concentrations

BACKGROUND

Numerous clinical studies suggest that gadobenate dimeglumine is diagnostically superior to other gadolinium chelates for MR imaging applications, including contrast-enhanced MR angiography (CE-MRA). However, confirmatory in-vitro phantom studies have thus far been lacking.

PURPOSE

To evaluate the difference in signal intensity achieved with the high-relaxivity MR contrast agent gadobenate dimeglumine (MultiHance) relative to that achieved with the standard-relaxivity non-specific agent gadopentetate dimeglumine (Magnevist) at different concentrations using an in-vitro phantom study design.

MATERIAL AND METHODS

Test tubes with whole human blood were prepared with concentrations of gadobenate dimeglumine or gadopentetate dimeglumine ranging from 0 to 12 mM. A three-dimensional (3D) T1-weighted gradient echo sequence normally used for CE-MRA of the renal arteries was performed at flip angles of 25° and 35°. The signal-to-noise ratio (SNR) was calculated for all concentrations of both contrast agents. Furthermore a Look-Locker sequence was used and quantitative T1 mapping was performed for all the test tubes. The contrast agent concentration in the aorta was simulated using previously published data on T1 in the aorta during the first pass of a contrast agent. The differences between gadobenate dimeglumine and gadopentetate dimeglumine were compared at the simulated concentrations.

RESULTS

The SNR achieved with gadobenate dimeglumine was consistently greater than that achieved with gadopentetate dimeglumine at all concentrations. An improvement of 15-25% in SNR was obtained when increasing the flip angle from 25° to 35°. The relative improvement in SNR with gadobenate dimeglumine relative to gadopentetate dimeglumine ranged from 25-72% and was markedly greater at lower concentrations with a flip angle of 35°.

CONCLUSION

Our findings suggest that the relative benefit of gadobenate dimeglumine over gadopentetate dimeglumine for CE-MRA applications is greater at lower concentrations.

Intra-individual randomised comparison of gadobutrol 1.0 M versus gadobenate dimeglumine 0.5 M in patients scheduled for preoperative breast MRI

OBJECTIVE

To demonstrate non-inferiority of gadobutrol versus gadobenate dimeglumine by intra-individually comparing 0.1 mmol/kg body weight doses for contrast-enhanced breast magnetic resonance imaging (MRI) and prospectively evaluating lesion detection and characterisation in a multicentre trial.

METHODS

Two identical breast MRI examinations were performed in 72 patients with biopsy-proven breast cancer, separated by 1-7 days. Gadobutrol 1.0 M or gadobenate 0.5 M were administered in a randomised order. Lesion detection and characterisation were performed by two independent blinded readers. Lesion tracking, which compared on-site readings and histology from surgery or biopsy, was performed by a third reader. Differences in lesion detection and characterisation were compared between the two contrast agents.

RESULTS

Among 103 lesions, 96 were malignant and 7 were benign. No difference in lesion detection was identified between the contrast agents (82.33 % for gadobutrol, 81.60 % for gadobenate). Assessment of sensitivity in lesion characterisation and Breast Imaging Reporting and Data Systems showed no difference between gadobutrol (92.63 %) and gadobenate (90.53 %). Regarding morphology, there was more non-focal enhancement for gadobutrol than for gadobenate (P = 0.0057).

CONCLUSION

Non-inferiority of gadobutrol compared with gadobenate was demonstrated for breast lesion detection and sensitivity in lesion characterisation in breast MRI.

Effect of preoperative breast magnetic resonance imaging on surgical decision making and cancer recurrence rates

PURPOSE

To evaluate breast magnetic resonance imaging (MRI) for cancer staging and surgical planning in patients with known breast cancer, and to evaluate recurrence rates at long-term follow-up.

METHODS AND MATERIALS

Institutional review board approval and patient consent were obtained. Preoperative MRI with 0.1 mmol/kg gadobenate dimeglumine (MultiHance) was performed in 203/274 women with confirmed breast cancer. The sensitivity, accuracy, and positive predictive value of MRI compared with mammography/ultrasound for malignant lesion detection were calculated, and the effect of MRI on surgical decision making evaluated. The cancer recurrence rate was determined for 172 patients with available 2- to 8-year follow-up data.

RESULTS

Mammography/ultrasound detected 229 suspicious lesions. Breast MRI detected 159 additional lesions in 48/203 (23.6%) patients; of which 110/110 were correctly classified as malignant and 28/49 as benign, giving sensitivity, accuracy, and positive predictive values for malignant lesion detection of 100% (110/110), 86.8% (138/159), and 84.0% (110/131), respectively. MRI revealed unsuspected multifocal, multicentric, and synchronous contralateral lesions in 7/48, 16/48, and 16/48 patients, respectively, and pectoralis muscle infiltration in 3/38 patients. In 6/48 women, MRI revealed lesions not seen on conventional imaging (n = 5) or discounted suspected multifocal disease (n = 1). Therapy was changed for 50/203 (24.6%) patients: 38 patients underwent more extensive surgery and 12 less extensive surgery. Six (3.5%) recurrences occurred, in all cases at >4 years.

CONCLUSION

Breast MRI positively affects patient management and is recommended for mapping tumor extent in patients with newly diagnosed cancer. The cancer recurrence rate at long-term follow-up after MRI is low.

Solid hypervascular liver lesions: accurate identification of true benign lesions on enhanced dynamic and hepatobiliary phase magnetic resonance imaging after gadobenate dimeglumine administration

PURPOSE

To evaluate hepatobiliary phase magnetic resonance imaging with gadobenate dimeglumine for differentiation of benign hypervascular liver lesions from malignant or high-risk lesions.

METHODS AND MATERIALS

Retrospective assessment was performed of 550 patients with 910 hypervascular lesions (302 focal nodular hyperplasia [FNH], 82 nodular regenerative hyperplasia [NRH], 59 hepatic adenoma or liver adenomatosis [HA/LA], 329 hepatocellular carcinomas [HCC], 12 fibrolamellar-HCC [FL-HCC], 21 peripheral cholangiocarcinomas [PCC], 105 metastases). Imaging was performed before and during the arterial, portal-venous, equilibrium, and hepatobiliary phases after gadobenate dimeglumine administration (0.05 mmol/kg). Histologic confirmation was available for ≥1 lesion per patient, except for patients with suspected FNH (diagnosis based on characteristic enhancement/follow-up). Lesion differentiation (benign/malignant) on the basis of contrast washout and lesion enhancement (hypo-/iso-/hyperintensity) was assessed (sensitivity, specificity, accuracy, PPV, and NPV) relative to histology or final diagnosis.

RESULTS

On portal-venous or equilibrium phase images, washout was not seen for 208 of 526 (39.5%) malignant (HCC, FL-HCC, PCC, metastases) and high-risk (HA/LA) lesions. Conversely, only 5 of 384 (1.3%) true benign lesions (FNH/NRH) showed washout. Taking washout as indicating malignancy, the sensitivity, specificity, and accuracy for malignant lesion identification during these phases was 61.8%, 98.7%, and 77.4%. On hepatobiliary phase images, 289 of 302 FNH, 82 of 82 NRH, 1 of 59 HA or LA, 62 of 341 HCC or FL-HCC, and 2 of 105 metastases were hyperintense or isointense. Taking iso- or hyperintensity as an indication for lesion benignity, the sensitivity, specificity, accuracy, PPV, and NPV for benign lesion identification was 96.6%, 87.6%, 91.4%, 85.1%, and 97.3%, respectively.

CONCLUSIONS

Hepatobiliary phase imaging with gadobenate dimeglumine is accurate for distinguishing benign lesions from malignant or high-risk lesions. Biopsy should be considered for hypointense lesions on hepatobiliary phase images after gadobenate dimeglumine.

Current Status and New Developments in Breast MRI

SUMMARY: Breast magnetic resonance imaging (MRI) is the most sensitive imaging modality for the detection of breast cancer. Its specificity is equivalent to that of mammography. Nowadays, breast MRI is an absolutely essential breast imaging method. Technical innovations allow dynamic contrast-enhanced (DCE) MRI of both breasts with high image quality. Thereby, DCE breast MRI should always be performed with regard to current standards. New quantitative techniques such as diffusion-weighted MRI are promising. However, they still have potential pitfalls, in particular with regard to the diagnosis of non-mass lesions and small breast lesions. Ongoing technical innovations can possibly help to further optimize breast MRI.

Incidental enhancing lesions found on preoperative breast MRI: management and role of second-look ultrasound

PURPOSE

This study prospectively assessed second-look ultrasound (US) for the evaluation of incidental enhancing lesions identified on preoperative breast magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Between 2004 and 2007, 182 patients with malignant breast lesions detected on US and/or X-ray mammography and confirmed by cytology/histology underwent preoperative breast contrast-enhanced (CE)-MRI. Patients with incidental lesions on breast MRI underwent second-look high-resolution US directed at the site of the incidental finding. Diagnosis of incidental lesions was based on biopsy or 24-month follow-up.

RESULTS

Breast MRI detected 55 additional lesions in 46/182 (25.2%) patients. Forty-two of 55 (76.3%) lesions were detected on second-look US in 38/46 (82.6%) patients. Malignancy was confirmed for 24/42 (57.1%) correlate lesions compared with 7/13 (53.8%) noncorrelate lesions. Second-look US depicted 8/9 (88.8%) Breast Imaging Reporting and Data System (BI-RADS) 5, 16/22 (72.7%) BI-RADS 4 and 18/24 (75%) BI-RADS 3 lesions. Sensitivity, specificity, accuracy and positive and negative predictive values for lesion detection/diagnosis was 100%, 88.9%, 94.6%, 90.3% and 100% for MRI and 64.3%, 70.4%, 67.3%, 69.2% and 65.5% for second-look US. Improved performance for US was obtained when masslike lesions only were considered.

CONCLUSIONS

Second-look US is a confirmatory method for incidental findings on breast MRI, particularly for mass-like lesions.

Multicenter, double-blind, randomized, intraindividual crossover comparison of gadobenate dimeglumine and gadopentetate dimeglumine for MR angiography of peripheral arteries

PURPOSE

To prospectively compare the image quality and diagnostic performance achieved with doses of gadobenate dimeglumine and gadopentetate dimeglumine of 0.1 mmol per kilogram of body weight in patients undergoing contrast material-enhanced magnetic resonance (MR) angiography of the pelvis, thigh, and lower-leg (excluding foot) for suspected or known peripheral arterial occlusive disease.

MATERIALS AND METHODS

Institutional review board approval was granted from each center and informed written consent was obtained from all patients. Between November 2006 and January 2008, 96 patients (62 men, 34 women; mean age, 63.7 years +/- 10.4 [standard deviation]; range, 39-86 years) underwent two identical examinations at 1.5 T by using three-dimensional spoiled gradient-echo sequences and randomized 0.1-mmol/kg doses of each agent. Images were evaluated on-site for technical adequacy and quality of vessel visualization and offsite by three independent blinded readers for anatomic delineation and detection/exclusion of pathologic features. Comparative diagnostic performance was determined in 31 patients who underwent digital subtraction angiography. Data were analyzed by using the Wilcoxon signed-rank, McNemar, and Wald tests. Interreader agreement was determined by using generalized kappa statistics. Differences in quantitative contrast enhancement were assessed and a safety evaluation was performed.

RESULTS

Ninety-two patients received both agents. Significantly better performance (P < .0001; all evaluations) with gadobenate dimeglumine was noted on-site for technical adequacy and vessel visualization quality and offsite for anatomic delineation and detection/exclusion of pathologic features. Contrast enhancement (P < or = .0001) and detection of clinically relevant disease (P < or = .0028) were significantly improved with gadobenate dimeglumine. Interreader agreement for stenosis detection and grading was good to excellent (kappa = 0.749 and 0.805, respectively). Mild adverse events were reported for four (six events) and five (eight events) patients after gadobenate dimeglumine and gadopentetate dimeglumine, respectively.

CONCLUSION

Higher-quality vessel visualization, greater contrast enhancement, fewer technical failures, and improved diagnostic performance are obtained with gadobenate dimeglumine, relative to gadopentetate dimeglumine, when compared intraindividually at 0.1-mmol/kg doses in patients undergoing contrast-enhanced MR angiography for suspected peripheral arterial occlusive disease.

Relating dose of contrast media administered to uptake and washout of malignant lesions on DCEMRI of the breast

RATIONALE AND OBJECTIVES

To quantify the relationship between dose of contrast administered and contrast kinetics of malignant breast lesions.

MATERIALS AND METHODS

A total of 108 patients with 120 malignant lesions were selected for an institutional review board-approved review. Dynamic magnetic resonance protocol: one pre- and three or five post-contrast (at a fixed volume of 20 mL of 0.5 M gadodiamide) images. Patients were stratified into groups based on dose of contrast administered, after calculation of body weight (kg): Dose Group 1, <0.122 mmol/kg; Dose Group 2, 0.123-0.155 mmol/kg; Dose Group, 3 > 0.155 mmol/kg. Analysis of kinetic curve shape was made according to the Breast Imaging Reporting and Data System lexicon. Several quantitative parameters were calculated including initial and peak enhancement percentage (E(1) and E(peak)). Linear regression was used to model the variation of kinetic parameters with dose.

RESULTS

There was no difference found in the qualitative Breast Imaging Reporting and Data System descriptors of curve shape between the three dose groups. There was a trend for E(1) and E(peak) to increase from Dose Group 1 to Dose Group 3 in malignant lesions overall, as well as in invasive ductal carcinoma lesions separately. Each decrement/increment of 0.05 mmol/kg in dose yielded a decrease/increase of 78% and 97% in E(1) for in situ and invasive cancers, respectively.

CONCLUSION

Contrast should be administered at fixed dose to achieve comparable levels of lesion uptake in women of different weights. Our results suggest that reducing the contrast administered to 0.05 mmol/kg, as has been suggested for patients at risk of developing nephrogenic systemic fibrosis, could substantially decrease the observed initial enhancement in some cancers.

Diffusion-weighted imaging in breast lesion evaluation

PURPOSE

The purpose of this study was to investigate the ability of diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC) in the detection and characterisation of breast lesions.

MATERIALS AND METHODS

From September 2005 to September 2007, 86 patients with breast lesions who underwent magnetic resonance imaging (MRI) in our department were included in our study. MRI was performed with a 1.5-T unit using a standard protocol including DWI sequence. For each breast lesion, the ADC value was calculated and compared with that of normal breast tissue and to the definitive pathological diagnosis. Mann-Whitney U and Kruskal-Wallis tests were used for statistical analysis.

RESULTS

A total of 126 breast lesions were detected. Pathology results revealed 100 malignant and 26 benign lesions. Mean diameter of lesions was 26.02 mm (range 4-90 mm), including 52 lesions <or=15 mm in size. Mean ADC value of normal glandular tissue was 1.55x10(-3) mm(2)/s. Mean ADC value of malignant lesions was 0.97x10(-3) mm(2)/s. Mean ADC value for benign lesions was 1.66x10(-3) mm(2)/s. Benign lesions showed ADC values significantly higher than malignant lesions (p<0.0001).

CONCLUSIONS

DWI provides reliable information to support MRI diagnosis of breast masses. ADC value appears a promising adjunctive parameter in distinguishing malignant from benign breast lesions.

Comparison of 99mTc-DMSA dual-head SPECT versus high-resolution parallel-hole planar imaging for the detection of renal cortical defects

OBJECTIVE

Renal cortical scintigraphy with (99m)Tc dimer captosuccinic acid (DMSA) is the standard method to detect acute pyelonephritis and cortical scarring. Different acquisition methods have been used: planar parallel-hole or pinhole collimation and single photon emission tomography (SPECT). Publications support the superiority of each; few comparative studies have been reported, with mixed results. We have compared planar parallel-hole cortical scintigraphy and dual-head SPECT for detection of cortical defects.

MATERIALS AND METHODS

Forty patients (37 children, 3 adults; 9 male, 31 female) were imaged 3 hours after injection of (99m)Tc-DMSA with dual-head SPECT and planar imaging (posterior, left, and right posterior oblique views with a parallel-hole collimator). For each patient, planar and SPECT images were evaluated at different sittings, in random order, by three independent observers. Twelve cortical segments were scored as normal or reduced uptake. The linear correlation coefficient for the number of abnormal segments detected between readers, techniques, and segments was calculated.

RESULTS

No significant difference was seen in the average number of abnormal segments detected by planar versus SPECT imaging; 2.1 for planar imaging and 2.2 for SPECT (p = 0.84, two-tailed). For all observers, the average correlation coefficient for SPECT alone, planar imaging alone, and between techniques (SPECT vs planar imaging) was high (r = 0.93-0.94). Applying nonparametric Spearman's rank analysis, the average correlation remained high (r = 0.70-0.75). Correlation between readers, techniques, and segments for methods and readers was also good (r = 0.69-0.77).

CONCLUSION

(99m)Tc-DMSA renal cortical imaging using dual-head SPECT offers no statistically significant diagnostic advantage over planar imaging for detection of cortical defects.

The challenge of imaging dense breast parenchyma: is magnetic resonance mammography the technique of choice? A comparative study with x-ray mammography and whole-breast ultrasound

PURPOSE

To establish the value of magnetic resonance imaging (MRI) of the breast in comparison to x-ray mammography and ultrasound for breast cancer evaluation in women with dense breast parenchyma.

MATERIALS AND METHODS

Two hundred thirty-eight women with dense breast parenchyma who were suspicious for breast cancer or inconclusive for the presence of breast lesions based on clinical examination, ultrasound or x-ray mammography, and who underwent breast MRI at 1.5 T before and after administration of 0.1 mmol/kg gadobenate dimeglumine were evaluated. Lesions considered malignant (Breast Imaging Reporting and Data System (BI-RADS) 4 or 5) on x-ray mammography and/or ultrasound and as BI-RADS 3, 4, or 5 on MRI were evaluated histologically. Other lesions were followed up at 6 and/or 18 months. The diagnostic performance (sensitivity, specificity, accuracy, and positive and negative predictive values) of each technique was determined and compared using a general linear mixed model with appropriate correction for multiplicity.

RESULTS

At final diagnosis 121 of 238 (50.8%) women had one or more confirmed malignant lesions, whereas 117 (49.2%) had benign lesions or no lesions. Among 97 women who underwent all 3 techniques more lesions (malignant and benign) were detected with breast MRI (n = 135) than with x-ray mammography (n = 85) or ultrasound (n = 107) and diagnostic confidence was greater. In terms of patient-based diagnostic accuracy breast MRI was significantly (P[r] < 0.0001) superior to both x-ray mammography and ultrasound (96.9% accuracy for MRI vs. 60.8% for mammography and 66.0% for US). Malignant lesions were histologically confirmed in 55 of 97 women who underwent all 3 techniques. Breast MRI detected more cases of multifocal, multicentric, and contralateral disease and fewer misdiagnoses occurred. Overall, breast MRI led to a modification of the surgical approach for 28 (23.1%) of the 121 women with diagnosed malignant disease.

CONCLUSION

Breast MRI should be considered for routine breast cancer evaluation in women with dense breast parenchyma.

[Breast MRI: the usefulness of diffusion-weighted sequences for differentiating between benign and malignant lesions]

OBJECTIVE

To evaluate the usefulness of diffusion-weighted MRI sequences and of the apparent diffusion coefficient (ADC) to differentiate between benign and malignant breast lesions.

MATERIAL AND METHODS

We prospectively studied 88 patients (aged 31 to 79 years) with 94 lesions (80 malignant and 14 benign) who were referred for preoperative local staging. All patients underwent dynamic MRI examination after intravenous contrast administration and a diffusion-weighted sequence with ADC calculation. The results obtained at diffusion-weighted imaging were correlated with those obtained at histological examination.

RESULTS

The mean value of the ADC for malignant lesions (1.12+/-0.25x10(-3)mm(2)/s) was significantly lower (p<0.001) than for benign lesions (1.61+/-0.52x10(-3)mm(2)/s). No significant differences in ADC values were found between the different subtypes of invasive carcinomas or between intraductal carcinoma and invasive carcinoma (p>0.05). Using an ADC lower than 0.95x10(-3)mm(2)/s as a threshold for malignancy, the sensitivity is 52% and the specificity is 100%.

CONCLUSION

Diffusion-weighted sequences provide additional information in breast MRI that is useful for differentiating between benign and malignant lesions, thus improving the specificity of the technique.

Assessment of adverse reaction rates to a newly approved MRI contrast agent: review of 23,553 administrations of gadobenate dimeglumine

OBJECTIVE

With the introduction of a newly approved MR contrast agent across a health care system encompassing 13 hospitals and associated imaging centers, the opportunity arose to compare the rates of adverse reactions in seven of these facilities with reactions reported in the literature. Data were collected to assess the relative risk of using gadobenate dimeglumine compared with published data for other approved agents and for this agent in preclinical testing.

SUBJECTS AND METHODS

As part of regular quality assurance procedures, technologists recorded contrast administrations and related adverse reactions, including the type of reaction and treatments rendered, on log sheets. All data were reviewed weekly by the institutional director of MR services and were evaluated globally and by site.

RESULTS

Over 13 months, 23,553 doses of gadobenate dimeglumine were administered. One hundred seventy-eight reactions were recorded (0.76% of contrast-enhanced examinations), of which 22 required treatment (13% of reactions) and eight (5% of reactions) qualified as serious.

CONCLUSION

With the introduction of the most recent MR contrast agent approved for use in the United States, our interest in its substantial potential clinical benefits that would result from its increased relaxivity was balanced by concern that the rate of adverse effects may increase. This concern has been ameliorated with the findings of rates of adverse reactions that are comparable to those published for other MR contrast agents.

Recent advances in breast MRI and MRS

Breast MRI is an area of intense research and is fast becoming an important tool for the diagnosis of breast cancer. This review covers recent advances in breast MRI, MRS, and image post-processing and analysis. Several studies have explored a multi-parametric approach to breast imaging that combines analysis of traditional contrast enhancement patterns and lesion architecture with novel methods such as diffusion, perfusion, and spectroscopy to increase the specificity of breast MRI studies. Diffusion-weighted MRI shows some potential for increasing the specificity of breast lesion diagnosis and is even more promise for monitoring early response to therapy. MRS also has great potential for increasing specificity and for therapeutic monitoring. A limited number of studies have evaluated perfusion imaging based on first-pass contrast bolus tracking, and these clearly identify that vascular indices have great potential to increase specificity. The review also covers the relatively new acquisition technique of MR elastography for breast lesion characterization. A brief survey of image processing algorithms tailored for breast MR, including registration of serial dynamic images, segmentation and extraction of morphological features of breast lesions, and contrast uptake modeling, is also included. Recent advances in MRI, MRS, and automated image analysis have increased the utility of breast MR in diagnosis, screening, management, and therapy monitoring of breast cancer.