Chapter

Techniques for Performing Abbreviated Breast Magnetic Resonance Imaging in Abbreviated MRI of the Breast: A Practical Guide. CE Comstock and CK Kuhl, eds. New York, NY: Thieme Medical Publishers, Inc. 2018, p. 45-64.

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Abstract

The goal of abbreviated breast MRI is to maximize sensitivity to breast cancer in a short (less than 5-minute) imaging session that screens women for breast cancer. (1,2) The brief imaging duration must include acquisition of a localizing series, a single T1-weighted pre-contrast series, contrast injection, and acquisition of an single T1-weighted post-contrast series. To perform the entire imaging session in less than 5 minutes, each pre- or post-contrast series should image all breast tissue in two minutes or less (Figure 1). Since interpretation of abbreviated MRI is done primarily from the subtracted series (pre- subtracted from post-contrast series, voxel by voxel) and maximum intensity projection (MIP) reconstructions of the subtracted series, pre- and post-contrast series should be identical and acquired without motion during, or misregistration between, the two series. Modern breast MRI equipment and fast gradient-echo techniques make this feasible while maintaining the essential features that make breast MRI highly sensitive to breast cancer: high spatial resolution, thin slices, and good signal-to-noise ratios over both breasts. Abbreviate breast MRI was initially proposed and validated by Kuhl, et al, using a two-dimensional (2D, or planar) non-fat-saturation pre- and post-contrast multi-slice gradient-echo series pre- and post-contrast series pair acquired in a total imaging time of 3 minutes, with breast immobilization. (1) Their results showed that the high sensitivity, specificity, and negative predictive value of a full diagnostic breast MRI protocol could be maintained with an abbreviated MRI protocol that significantly shortens both image acquisition and interpretation times. Subsequent studies have demonstrated that similar high sensitivity to breast cancer can be maintained using three-dimensional (3D, or volume) fat-saturated approaches to abbreviated breast MRI. (3-5) This chapter will discuss the specific equipment and imaging techniques needed to perform abbreviated breast MRI and the technical aspects of breast MRI that can maximize sensitivity in the process. Examples of ideal and less-than-ideal image acquisitions will be presented to illustrate techniques and pitfalls of abbreviated breast MRI. Finally, contrast agents suitable for abbreviated breast MRI and some practical considerations in the delivery of contrast agents will be discussed.

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To prospectively compare 0.1 mmol/kg doses of gadobenate dimeglumine and gadopentetate dimeglumine for contrast-enhanced MRI of brain lesions at 3 Tesla (T). Forty-six randomized patients underwent a first examination with gadobenate dimeglumine (n = 23) or gadopentetate dimeglumine (n = 23) and then, after 2-7 days, a second examination with the other agent. Contrast administration (volume, rate), sequence parameters (T1wSE; T1wGRE), and interval between injection and image acquisition were identical for examinations in each patient. Three blinded neuroradiologists evaluated images qualitatively (lesion delineation, lesion enhancement, global preference) and quantitatively (lesion-to-brain ratio [LBR], contrast-to-noise ratio [CNR], % lesion enhancement). Differences were assessed using Wilcoxon's signed-rank test. Reader agreement was determined using kappa (kappa) statistics. There were no demographic differences between groups. The three readers preferred gadobenate dimeglumine globally in 22 (53.7%), 21 (51.2%), and 27 (65.9%) patients, respectively, compared with 0, 1, and 0 patients for gadopentetate dimeglumine. Similar significant (P < 0.001) preference was expressed for lesion border delineation and enhancement. Reader agreement was consistently good (kappa = 0.48-0.64). Significantly (P < 0.05) higher LBR (+43.5- 61.2%), CNR (+51.3-147.6%), and % lesion enhancement (+45.9-49.5%) was noted with gadobenate dimeglumine. Brain lesion depiction at 3T is significantly improved with 0.1 mmol/kg gadobenate dimeglumine.
Article
The objective of our study was to intraindividually compare 0.1 mmol/kg doses of gadobenate dimeglumine and gadopentetate dimeglumine for contrast-enhanced breast MRI. Forty-seven women (mean age +/- SD, 50.8 +/- 12.9 years) with breast lesions classified as BI-RADS category 3, 4, or 5 for suspicion of malignancy underwent two identical MR examinations at 1.5 T separated by 48-72 hours. T1-weighted gradient-echo images were acquired before contrast administration and at 2-minute intervals after the randomized injection of gadopentetate dimeglumine or gadobenate dimeglumine at 2 mL/s. Two blinded readers evaluated randomized image sets for lesion detection and differentiation as benign or malignant compared with histology. The McNemar exact test and the generalized estimating equation (GEE) were used to compare lesion detection rates and diagnostic performance in terms of sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV). Histopathology data were available for 78 lesions. Significantly more lesions overall (75/78 [96%] vs 62/78 [79%], respectively; p = 0.0002) and significantly more malignant lesions (49/50 [98%] vs 38/50 [76%]; p = 0.0009) were detected with gadobenate dimeglumine than gadopentetate dimeglumine. All detected malignant lesions were correctly diagnosed with both agents. More detected benign lesions were correctly diagnosed with gadobenate dimeglumine than with gadopentetate dimeglumine (20/26 [77%] vs 17/24 [71%], respectively). Differentiation of lesions was significantly (p = 0.0001) better with gadobenate dimeglumine. Significantly better diagnostic performance was noted with gadobenate dimeglumine than with gadopentetate dimeglumine, respectively, for sensitivity (98.0% vs 76.0%; p = 0.0064), accuracy (88.5% vs 69.2%; p = 0.0004), PPV (86.0% vs 76.0%; p = 0.0321), and NPV (95.2% vs 57.1%; p = 0.0003). Lesion detection and malignant-benign differentiation is significantly better with 0.1 mmol/kg gadobenate dimeglumine than 0.1 mmol/kg gadopentetate dimeglumine.
Article
To compare gadobenate dimeglumine (Gd-BOPTA) and gadopentetate dimeglumine (Gd-DTPA) for contrast-enhanced magnetic resonance (MR) angiography of the supraaortic vessels at 3 Tesla. Twelve healthy volunteers each underwent two contrast-enhanced magnetic resonance angiography examinations, one with Gd-BOPTA and one with Gd-DTPA each at a dose of 0.1 mmol/kg bodyweight. The 2 examinations were performed in randomized order and were separated by at least 72 hours. Imaging was performed in the coronal plane at 3T (Magnetom TIM Trio Siemens) using a 12-channel neurovascular array coil. The MR sequence parameters were identical for all examinations. Maximum intensity projection reconstructions were evaluated separately and in matched-pairs by a single independent blinded reviewer in terms of qualitative (5-point scales for technical quality and vessel delineation) and quantitative (relative contrast-to-noise ratio) contrast enhancement across 19 arteries/arterial segments comprising the internal carotid arteries; anterior, middle, and posterior cerebral arteries; vertebral arteries; and basilar artery. Findings were compared using the Wilcoxon signed rank test. The mean technical quality across all examinations was significantly (P = 0.031) greater after Gd-BOPTA. The overall median score for vessel delineation was also significantly higher for Gd-BOPTA than for Gd-DTPA (4.3 vs. 3.7; P = 0.005). Matched-pairs assessment revealed significant (P <or= 0.026) preference for Gd-BOPTA both globally and for assessments of the extracranial arteries, Circle of Willis and vessels distal to the Circle of Willis. The relative contrast-to-noise ratio was significantly (P <or= 0.021) greater after Gd-BOPTA, with overall increases of 23.3%, 26.7%, and 28.5% noted for the internal carotid, middle cerebral, and basilar arteries, respectively. Significantly improved image quality and contrast enhancement is achieved at 3T with 0.1 mmol/kg Gd-BOPTA compared with 0.1 mmol/kg Gd-DTPA.
Article
The fundamental limit for NMR imaging is set by an intrinsic signal-to-noise ratio (SNR) for a particular combination of rf antenna and imaging subjects. The intrinsic SNR is the signal from a small volume of material in the sample competing with electrical noise from thermally generated, random noise currents in the sample. The intrinsic SNR has been measured for a number of antenna-body section combinations at several different values of the static magnetic field and is proportional to B0. We have applied the intrinsic and system SNR to predict image SNR and have found satisfactory agreement with measurements on images. The relationship between SNR and pixel size is quite different in NMR than it is with imaging modalities using ionizing radiation, and indicates that the initial choice of pixel size is crucial in NMR. The analog of "contrast-detail-dose" plots for ionizing radiation imaging modalities is the "contrast-detail-time" plot in NMR, which should prove useful in choosing a suitable pixel array to visualize a particular anatomical detail for a given NMR receiving antenna.
Article
This review summarizes the physical basis of magnetic resonance (MR) imaging contrast agents, including both T1 agents, such as gadolinium-DTPA (diethylenetriaminepentaacetic acid), and T2 or T2* agents, such as superparamagnetic iron oxides. The maximization of image contrast and lesion visibility with contrast agents is described, and the use of contrast agents in MR angiography and perfusion imaging is discussed.
Article
To evaluate the ability of asymmetric half-Fourier three-dimensional (3D) magnetic resonance (MR) imaging to characterize signal intensity changes in breasts and axillae after contrast material injection and to compare the spatial resolution and measured signal intensity change of asymmetric and symmetric (keyhole) partial Fourier techniques. Imaging was performed in 28 adult patients by collecting a single full-Fourier 3D data set with bolus injection of contrast material during the last 10 seconds followed by collection of six half-Fourier 3D data sets without interimage delays. Postcontrast keyhole and half-Fourier images were formed from the same full-Fourier raw data set. The asymmetric half-Fourier 3D technique maintained the spatial resolution and lesion signal intensity of the full-Fourier image, whereas the 50% keyhole method degraded the spatial resolution by a factor of two and decreased the lesion signal intensity by 19% for a 2 x 2-pixel region of interest. Histopathologic correlation was attained in 32 lesions in 28 patients. Sensitivity was 100% (five of five) and specificity was 89% (24 of 27). The asymmetric half-Fourier 3D MR imaging technique allows imaging of both breasts and axillae without loss of lesion contrast or temporal resolution and provides the maximum spatial resolution and lesion signal intensity attainable for the views sampled.
Article
To define the range of normal contrast medium enhancement, the variability in contrast medium enhancement patterns in healthy premenopausal breast parenchyma, and the implications for management strategies in cases with incidental contrast medium-enhancing foci on breast magnetic resonance (MR) images. Twenty healthy volunteers (aged 21-41 years) were examined on a 1.5-T system (dynamic two-dimensional gradient-echo protocol with subtraction postprocessing) during each week of a menstrual cycle (group 1) or over 4 months (group 2). The authors evaluated changes in the number of enhancing foci and the respective enhancement patterns within a cycle and between cycles. Both diffuse and nodular enhancement of breast parenchyma occurred during all phases of the menstrual cycle, especially in weeks 1 and 4. Enhancement was lowest in week 2. A total of 60 enhancing foci (73% of which resolved completely during follow-up) were found in 16 of 20 volunteers. Twenty-six foci demonstrated enhancement velocities beyond the malignancy threshold (>80% increase in the 1st minute). Contrast-enhancing foci are normal in healthy premenopausal breasts, even when formal malignancy criteria of enhancement velocity are met. This has to be kept in mind to avoid false-positive results, especially in younger patients.
Article
The incidence of synchronous bilateral breast cancers has been reported to be between 3.4% and 7.4%, as detected on mammography, physical examination, or both. We undertook a study to determine how often magnetic resonance (MR) imaging detects a contralateral abnormality in patients with known breast carcinoma. As part of an institutional review board (IRB) -approved research protocol, 17 patients with pathologically proven invasive carcinoma underwent preoperative MR imaging of both breasts using a T1-weighted, high-resolution gradient echo sequence (precontrast and postcontrast), an echo-planar sequence during administration of gadolinium, and a T2-weighted, fast-spin echo sequence. The morphology and dynamic enhancement of lesions in both breasts were assessed. Biopsy was recommended for any lesion meeting set criteria. MR imaging identified all 17 known invasive cancers in the breast of concern on mammography or physical examination. Five of 17 patients (29%) had 10 contralateral lesions identified on MR, for which biopsy was recommended. One of these lesions proved to represent a fibroadenoma. The other 9 lesions proved to represent a malignancy (6 invasive lobular, 2 infiltrating ductal, and 1 tubular). Four of the 17 patients (24%) with invasive cancer had contralateral synchronous cancers occult to physical examination, mammography, and ultrasonography. In this series, breast MR imaging of the breasts was more sensitive than mammography or physical examination in the detection of early breast cancer. Breast MR imaging of the contralateral breast may be of value as a routine screen in those patients with a known or suspected malignancy.
Article
To assess the vascular contrasting properties of a new MR contrast agent (gadobenate dimeglumine [Gd-BOPTA]), which presents higher relaxivity because of reversible, weak protein interaction, and, to compare these properties with a standard gadolinium agent. Two phase I trials compared intraindividually: (A) the vascular contrasting properties of Gd-BOPTA at three doses (0.0125, 0.05, and 0.2 mmol/kg body weight) and two flow rates (0.5 and 2.0 mL/s) in 10 volunteers; and (B) 0.1 mmol/kg body weight doses of Gd-BOPTA and Gd-DTPA at 2.0 mL/s using a modified magnetic resonance angiography (MRA) sequence with a temporal resolution of 1 s/f. Quantitative (ROI analysis) and fully blinded qualitative (reader review) assessment of images was performed. A dose of 0.2 mmol/kg resulted in higher maximum intensities, longer median peak widths, and larger areas under the curve than did the lower doses (0.0125 mmol/kg and 0.05 mmol/kg). In the intraindividual comparison, Gd-BOPTA demonstrated significantly better vascular enhancement characteristics in terms of signal peak duration (p < 0.05), maximum signal intensity (p < 0.05), and area under the enhancement curve (p < 0.01). The multireader assessment for overall vascular contrast preferred Gd-BOPTA at p < 0.03. Gd-BOPTA was shown to exhibit preferential and different vascular enhancement properties as compared with Gd-DTPA for MRA.
Article
The purpose of this study was to determine the frequency and positive predictive value of biopsy performed on the basis of MR imaging findings in the contralateral breast in women with recently diagnosed breast cancer. We performed a retrospective review of records of 1336 consecutive breast MR imaging examinations over a 2-year period. Of these examinations, 223 imaged the asymptomatic, mammographically normal contralateral breast in women whose breast cancer was diagnosed within 6 months preceding MR imaging. Records of these 223 examinations were reviewed to determine the frequency of recommending contralateral breast biopsy and the biopsy results. Contralateral breast biopsy was recommended in 72 (32%) of 223 women and performed in 61 women. Cancer occult to mammography and physical examination was detected by MR imaging in 12 women, constituting 20% (12/61) of women who underwent contralateral biopsy and 5% (12/223) of women who underwent contralateral breast MR imaging. Among these 12 cancers, six (50%) were ductal carcinoma in situ (DCIS) and six (50%) were infiltrating carcinoma. The median size of infiltrating carcinoma was 0.5 cm (range, 0.1-1.0 cm). Contralateral biopsy revealed benign (n = 31) or high-risk (n = 18) lesions in 49 women, constituting 80% (49/61) of women who underwent contralateral biopsy and 22% (49/223) of women who underwent contralateral MR imaging. In women with recently diagnosed breast cancer, MR imaging of the contralateral breast led to a biopsy recommendation in 32%. Cancer was found in 20% of women who underwent contralateral breast biopsy and in 5% of women who underwent contralateral breast MR imaging.
Article
Gadobenate dimeglumine (Gd-BOPTA) has a two-fold higher T1 relaxivity compared with gadopentetate dimeglumine (Gd-DTPA) and can be used for both dynamic and delayed liver MRI. This intraindividual, crossover study was conducted to compare 0.05 mmol/kg Gd-BOPTA with 0.1 mmol/kg Gd-DTPA for liver MRI. Forty-one patients underwent two identical MR examinations separated by >or= 72 hours. Precontrast T1-FLASH-2D and T2-TSE sequences and postcontrast T1-FLASH-2D sequences were acquired during the dynamic and delayed (1-2 hours) phases after each contrast injection. Images were evaluated on-site by two independent, blinded off-site readers in terms of confidence for lesion detection, lesion number, character and diagnosis, enhancement pattern, lesion-to-liver contrast, and benefit of dynamic and delayed scans. Additional on-site evaluation was performed of the overall diagnostic value of each agent. Superior diagnostic confidence was noted by on-site investigators and off-site assessors 1 and 2 for 6, 4 and 2 patients with Gd-BOPTA, and for 3, 1 and 2 patients with Gd-DTPA, respectively. No consistent differences were noted for other parameters on dynamic phase images whereas greater lesion-to-liver contrast was noted for more patients on delayed images after Gd-BOPTA. More correct diagnoses of histologically confirmed lesions (n = 26) were made with the complete Gd-BOPTA image set than with the complete Gd-DTPA set (reader 1: 68% vs. 59%; reader 2: 78% vs. 68%). The overall diagnostic value was considered superior after Gd-BOPTA in seven patients and after Gd-DTPA in one patient. The additional diagnostic information on delayed imaging, combined with the possibility to use a lower overall dose to obtain similar diagnostic information on dynamic imaging, offers a distinct clinical advantage for Gd-BOPTA for liver MRI.
Article
To investigate the role of screening magnetic resonance (MR) imaging in the detection of synchronous contralateral breast cancer in patients with newly diagnosed breast cancer. Between January 1999 and July 2001, 182 patients with newly diagnosed breast cancer (after either core or excisional biopsy with positive or close margins of resection) underwent bilateral contrast material-enhanced MR imaging at 1.5 T with a dedicated bilateral breast multicoil array. The contralateral breast was imaged for cancer screening. Family history of breast cancer, index cancer histology, breast density, and age at diagnosis of first breast cancer were assessed as potential risk factors for synchronous contralateral breast cancer. Fifteen patients (8.2%) had a suspicious enhancing lesion depicted in the contralateral breast. Seven patients (3.8%) had malignant results: ductal carcinoma in situ (DCIS) in four, invasive ductal carcinoma with DCIS in two, and invasive ductal carcinoma in one. Eight patients (4.4%) had benign results: fibrocystic changes in four, atypical ductal hyperplasia in two, atypical lobular hyperplasia and focal lobular carcinoma in situ in one, and ductal hyperplasia in one. Six patients with negative MR findings underwent prophylactic mastectomy; no malignancy was found. No significant differences were noted among patients with true-positive (n = 7), false-positive (n = 8), or negative (n = 167) MR findings with regard to family history of breast cancer (P <.27), index cancer histology (P <.19), breast density (P <.34), or age at diagnosis of first breast cancer (P <.10). The preliminary results demonstrate the feasibility of using MR imaging of the breast in a screening role, specifically to evaluate the contralateral breast in patients with newly diagnosed breast cancer to detect mammographically and clinically occult synchronous breast cancer.
Article
To compare intraindividually gadobenate dimeglumine (Gd-BOPTA) with gadopentetate dimeglumine (Gd-DTPA) for multi-station MR Angiography of the run-off vessels. Twenty-one randomized healthy volunteers received either Gd-BOPTA or Gd-DTPA as a first injection and then the other agent as a second injection after a minimum interval of 6 days. Each agent was administered at a dose of 0.1 mmol/kg bodyweight followed by a 25-mL saline flush at a single constant flow rate of 0.8 mL/second. Images were acquired sequentially at the level of the pelvis, thigh, and calf using a fast three-dimensional (3D) gradient echo sequence. Source, subtracted source, maximum intensity projection (MIP), and subtracted MIP image sets from each examination were evaluated quantitatively and qualitatively on a segmental basis involving nine vascular segments. Significantly (P < 0.05) higher signal-to-noise and contrast-to-noise ratios were noted for Gd-BOPTA compared to Gd-DTPA, with the more pronounced differences evident in the more distal vessels. Qualitative assessmentrevealed no differences in the abdominal vasculature, a preference for Gd-BOPTA in the pelvic vasculature, and markedly better performance for Gd-BOPTA in the femoral and tibial vasculature. Summation of individual diagnostic quality scores for each segment revealed a significantly (P = 0.0001) better performance for Gd-BOPTA compared to Gd-DTPA. Greater vascular enhancement of the run-off vasculature is obtained after Gd-BOPTA, particularly in the smaller more distal vessels. Enhancement differences are not merely dose dependent, but may be due to different vascular enhancement characteristics of the agents.
Article
The purpose of this study was to compare contrast enhanced MR angiography (MRA) with gadopentetate dimeglumine (Gd-DTPA) to MRA with gadobenate dimeglumine (Gd-BOPTA), a high relaxivity paramagnetic contrast agent. Twelve patients referred for carotid artery stenosis were examined with MR angiography using a fast spoiled gradient echo sequence. Gd-DTPA and Gd-BOPTA enhanced MR angiography were performed within 48-72 hours using a dose of 0.1 mmol/kg for Gd-BOPTA and 0.2 mmol/kg for Gd-DTPA, at a flow rate of 2 ml/s. Images were evaluated by two blinded radiologists. Qualitative and quantitative evaluations were performed comparing the sets of images from the two examinations. Qualitative evaluation demonstrated superior arterial contrast enhancement and vessel conspicuity with Gd-BOPTA compared with Gd-DTPA. Quantita-tive evaluation showed an improvement in both signal intensity and contrast to noise ratio with Gd-BOPTA. The greater relaxivity of Gd-BOPTA, at lower doses, compared with Gd-DTPA, provides higher intravascular signal and signal to noise ratio. Gd-BOPTA appears to be an optimal contrast agent for contrast enhanced MRA.
Article
A study was undertaken to assess the diagnostic accuracy of contrast-enhanced MR mammography (MRM) of the contralateral breast in patients treated by breast-conserving therapy previously. A total of 119 patients underwent 145 standardized dynamic MR studies (1 T, T1-weighted 3D FLASH, 0.2 mmol Gd-DTPA/kg body weight). We retrospectively evaluated the results of conventional methods and MRM. A total of 11 contralateral carcinomas were present (detection rate 9%). The interval between treatment of the first primary and identification of contralateral malignancy was 9-80 months (mean 33 months). The MRM allowed detection of four otherwise occult malignancies. One of 11 cancer was missed on MRM due to benign appearance of enhancement. Compared with conventional methods MRM improved sensitivity (91 vs 64%) and specificity (90 vs 84%), respectively. This study suggests that additional MRM of the contralateral breast increases the diagnostic accuracy not only by enhancing the detection of second cancers but also by reducing false-positive results.
Article
To retrospectively compare three different doses of gadobenate dimeglumine with a standard dose of gadopentetate dimeglumine for magnetic resonance (MR) imaging evaluation of breast vessels and to evaluate the accuracy of one-sided increased vascularity seen on gadobenate dimeglumine-enhanced MR images as an indicator of ipsilateral breast cancer. The original study had local ethics committee approval; informed consent was obtained from all enrolled patients. Ninety-five patients known to have or suspected of having breast cancer were randomly assigned to four groups to receive gadobenate dimeglumine at a dose of 0.05, 0.10, or 0.20 mmol per kilogram of body weight or gadopentetate dimeglumine at a dose of 0.10 mmol/kg. T1-weighted gradient-echo MR images were acquired before and 2 minutes after intravenous contrast material injection. Subtracted images were used to obtain maximum intensity projections (MIPs). Two readers blinded to the type and dose of contrast agent administered scored the MIPs obtained in the dose groups for vessel number, length, and conspicuity from 0, which indicated absent or low breast vascularity, to 3, which indicated high breast vascularity. The sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) of one-sided increased vascularity in association with ipsilateral malignancy for 69 histopathologically confirmed lesions (reference standard) were determined after gadobenate dimeglumine-enhanced MR imaging. The mean MIP scores assigned to the gadobenate dimeglumine groups were significantly higher than those assigned to the gadopentetate dimeglumine group (P < or = .044). Histopathologic analysis revealed malignant lesions in 52 of 69 patients examined with gadobenate dimeglumine MR imaging: invasive ductal carcinoma in 45, invasive lobular carcinoma in four, and invasive mixed ductal-lobular carcinoma in three patients. Seventeen patients had benign lesions. Two cases of bilateral invasive cancer with symmetric breast vascular maps were excluded. Thus, the overall sensitivity, specificity, accuracy, PPV, and NPV of one-sided increased vascularity as a finding associated with ipsilateral malignancy were 88% (44 of 50 patients), 82% (14 of 17 patients), 87% (58 of 67 patients), 94% (44 of 47 patients), and 70% (14 of 20 patients), respectively. Gadobenate dimeglumine is effective for MR imaging evaluation of breast vessels at doses as low as 0.05 mmol/kg. One-sided increased vascularity is an MR imaging finding frequently associated with ipsilateral invasive breast cancer.
Article
To investigate prospectively the trade-off between temporal and spatial resolution in dynamic contrast material-enhanced bilateral magnetic resonance (MR) imaging of the breast. Informed consent and institutional review board approval were obtained. An intraindividual comparative study was performed in 30 patients (mean age, 53 years; age range, 27-70 years) with a total of 54 enhancing lesions (28 benign and 26 malignant) who underwent dynamic MR imaging of the breast twice, once with a standard dynamic protocol (256 x 256 matrix, 69 seconds per acquisition) and once on a separate day with a modified dynamic protocol (400 x 512 matrix, 116 seconds per acquisition). Systematic qualitative analysis of morphologic features and region-of-interest-based analysis of enhancement kinetics were performed. A statistically significant difference (generalized linear modeling) in enhancement rates of benign versus malignant lesions was lost when moving from the standard to the modified dynamic protocol. Kinetic information on signal intensity time course patterns was preserved. Delineation of lesion margins and internal architecture was clearly superior with the modified dynamic protocol, which allowed identification of lesion features associated with high positive predictive value or high negative predictive value for breast cancer. Ten benign lesions classified as Breast Imaging Reporting and Data System (BI-RADS) category 3 with the standard protocol were correctly downgraded to BI-RADS category 2 with the modified protocol owing to visualization of internal septations. Thirteen malignant lesions categorized as BI-RADS category 3 or 4 with the standard protocol were correctly upgraded to BI-RADS category 4 or 5 with the modified protocol owing to visualization of spicules or rim enhancement. Receiver operating characteristic analysis revealed a significantly larger area under the curve for results obtained with the modified dynamic protocol. Increased spatial resolution significantly improves diagnostic confidence and accuracy at dynamic MR imaging, even if this improvement occurs at the expense of temporal resolution. Loss of kinetic information regarding enhancement rates proved to be not diagnostically relevant because enhancement rates showed broad overlap between benign and malignant lesions and were therefore of only limited diagnostic use in the individual patient. Kinetic information regarding time course pattern was preserved and confirmed as having high specificity and high positive predictive value.
Article
To estimate the added cancer yield of magnetic resonance imaging (MRI) over mammography in the contralateral breast of patients with a recent diagnosis of breast cancer. We conducted a prospective, international study of mammography and MRI in women with a recent diagnosis of unilateral breast cancer. Each subject received a mammogram, clinical breast exam (CBE), and MRI of the unaffected breast within a 90 day time period. Definitive diagnosis of suspicious findings was determined through biopsy and central pathology review. Of the 103 eligible women included in study analyses, MRI detected 4 cancers in the contralateral breast while mammography detected none. MRI resulted in 12% (95% CI, 6%-20%) of women recommended for biopsy and 10% of women undergoing additional biopsy. The added cancer yield of MRI was 4% (95% CI, 1%-10%) and the positive predictive value of an abnormal MRI was 33% (95% CI, 10%-65%). Forty percent (4/10) of the biopsies performed based on the MRI recommendation were positive for malignancy. In women with a recent breast cancer diagnosis, approximately 4% will have an otherwise occult invasive breast cancer detected in the opposite breast by MRI alone.
Article
To characterize and compare commercially available contrast media (CM) for magnetic resonance imaging (MRI) in terms of their relaxivity at magnetic field strengths ranging from 0.47 T to 4.7 T at physiological temperatures in water and in plasma. Relaxivities also were quantified in whole blood at 1.5 T. Relaxivities of MRI-CM were determined by nuclear magnetic resonance (NMR) spectroscopy at 0.47 T and MRI phantom measurements at 1.5 T, 3 T, and 4.7 T, respectively. Both longitudinal (T1) and transverse relaxation times (T2) were measured by appropriate spin-echo sequences. Nuclear magnetic resonance dispersion (NMRD) profiles were also determined for all agents in water and in plasma. Significant dependencies of relaxivities on the field strength and solvents were quantified. Protein binding leads to both increased field strength and solvent dependencies and hence to significantly altered T1 relaxivity values at higher magnetic field strengths. Awareness of the field strength and solvent associated with relaxivity data is crucial for the comparison and evaluation of relaxivity values. Data observed at 0.47 T can thus be misleading and should be replaced by relaxivities measured at 1.5 T and at 3 T in plasma at physiological temperature.
Article
We sought to determine the relaxivity and accurate relaxation rates of Gd-DTPA, Gd-BT-DO3A, and Gd-BOPTA at 0.2, 1.5, and 3 T in human blood plasma. Contrast media concentrations between 0.01 and 16 mM in human plasma were used for relaxation measurements. The R1 and R2 relaxation rates and r1 and r2 relaxivities were determined. Gd-BOPTA produced the highest relaxation rates and relaxivities at all field strengths. The r1 and r2 values for Gd-BOPTA were 107-131% and 91-244% higher than for Gd-DTPA, respectively, and 72-98% and 82-166% higher than for Gd-BT-DO3A. Higher field strengths resulted in lower values of R1, R2, and r1 for all contrast agents tested and of r2 for Gd-DTPA and Gd-BT-DO3A. A linear dependence of R1 and R2 on concentration was found for Gd-DTPA and Gd-BT-DO3A and a nonlinear dependence for Gd-BOPTA for concentrations larger than 1 mM. The r1 and r2 relaxivity of Gd-BOPTA increased with decreasing concentration. Gd-BOPTA demonstrates the highest longitudinal r1 at all field strengths, which is ascribable to weak protein interaction. The R2/R1 ratio increases at higher field strength only for Gd-BOPTA, hence very short echo times are required for Gd-BOPTA to benefit from the higher longitudinal relaxivity.
Article
To prospectively compare gadobenate dimeglumine with gadopentetate dimeglumine (0.1 mmol per kilogram body weight) for enhanced magnetic resonance (MR) imaging of central nervous system (CNS) lesions. This study was HIPAA-compliant at U.S. centers and was conducted at all centers according to the Good Clinical Practice standard. Institutional review board and regulatory approval were granted; written informed consent was obtained. Seventy-nine men and 78 women (mean age, 50.5 years +/- 14.4 [standard deviation]) were randomized to group A (n = 78) or B (n = 79). Patients underwent two temporally separated 1.5-T MR imaging examinations. In randomized order, gadobenate followed by gadopentetate was administered in group A; order of administration was reversed in group B. Contrast agent administration (volume, speed of injection), imaging parameters before and after injection, and time between injections and postinjection acquisitions were identical for both examinations. Three blinded neuroradiologists evaluated images by using objective image interpretation criteria for diagnostic information end points (lesion border delineation, definition of disease extent, visualization of internal morphologic features of the lesion, enhancement of the lesion) and quantitative parameters (percentage of lesion enhancement, contrast-to-noise ratio [CNR]). Overall diagnostic preference in terms of lesion conspicuity, detectability, and diagnostic confidence was assessed. Between-group comparisons were performed with Wilcoxon signed rank test. Readers 1, 2, and 3 demonstrated overall preference for gadobenate in 75, 89, and 103 patients, compared with that for gadopentetate in seven, 10, and six patients, respectively (P < .0001). Significant (P < .0001) preference for gadobenate was demonstrated for diagnostic information end points, percentage of lesion enhancement, and CNR. Superiority of gadobenate was significant (P < .001) in patients with intraaxial and extraaxial lesions. Gadobenate compared with gadopentetate at an equivalent dose provides significantly better enhancement and diagnostic information for CNS MR imaging.
Article
The purpose was to evaluate the image quality of high-spatial resolution MRA of the renal arteries at 1.5 T after contrast-agent injection of 0.2 mmol/kg body weight (BW) in an interindividual comparison to 3.0 T after contrast-agent injection of 0.1 mmol/kg BW contrast agent (CA). After IRB approval and informed consent, 40 consecutive patients (25 men, 15 women; mean age 53.9 years) underwent MRA of the renal arteries either at a 1.5-T MR system with 0.2 mmol/kg BW gadobutrol or at a 3.0-T MR scanner with 0.1 mmol/kg BW gadobenate dimeglumine used as CA in a randomized order. A constant volume of 15 ml of these contrast agents was applied. The spatial resolution of the MRA sequences was 1.0 x 0.8 x 1.0 mm(3) at 1.5 T and 0.9 x 0.8 x 0.9 mm(3) at 3.0 T, which was achieved by using parallel imaging acceleration factors of 2 at 1.5 T and 3 at 3.0 T, respectively. Two radiologists blinded to the administered CA and the field strength assessed the image quality and the venous overlay for the aorta, the proximal and distal renal arteries independently on a four-point Likert-type scale. Phantom measurements were performed for a standardized comparison of SNR at 1.5 T and 3.0 T. There was no significant difference (p > 0.05) between the image quality at 3.0 T with 0.1 mmol/kg BW gadobenate dimeglumine compared to the exams at 1.5 T with 0.2 mmol/kg BW gadobutrol. The median scores were between 3 and 4 (good to excellent vessel visualization) for the aorta (3 at 1.5 T/4 at 3.0 T for reader 1 and 2). For the proximal renal arteries, median scores were 3 for the left and right renal artery at 1.5 T for both readers. At 3.0 T, median scores were 3 (left proximal renal artery) and 4 (right proximal renal artery) for reader 1 and 3 (left/right) for reader 2 at 3.0 T. For the distal renal arteries, median scores were between 2 and 3 at both field strengths (moderate and good) for both readers. The kappa values for both field strengths were comparable and ranged between 0.571 (moderate) for the distal renal arteries and 0.905 (almost perfect) for the proximal renal arteries. In the phantom measurements, a 40% higher SNR was found for the measurements at 3 T with gadobenate dimeglumine. High-spatial resolution renal MRA at 3.0 T with 0.1 mmol/kg BW gadobenate dimeglumine yields at least equal image quality compared with renal MRA at 1.5 T with 0.2 mmol/kg BW gadobutrol.
Relaxivity of MRI contrast agents
  • É Tóth
  • L Helm
  • A E Merbach
Tóth É, Helm L, Merbach AE. Relaxivity of MRI contrast agents. Topics in Current Chemistry 2002; 221, 61-101.
Bayer HealthCare Pharmaceuticals
  • N J Wayne
Wayne, NJ: Bayer HealthCare Pharmaceuticals; available at: https://www.radiologysolutions.bayer.com/products/mr/contrast/gadavist/, last accessed 5/2/2016.