In situ and minimally invasive breast cancer: morphologic and kinetic features on contrast-enhanced MR imaging

Purpose: This retrospective study was undertaken to investigate the morphologic and dynamic features of in situ and minimally invasive breast cancer on contrast-enhanced (c.-e.) MR imaging and to examine possible associations to pathology features. Material and methods: A total of 71 patients underwent MR imaging. T1-weighted FLASH-3D images were obtained before and after intravenous administration of Gd-DTPA. Histopathologic analysis of 78 lesions revealed ductal carcinoma in situ (DCIS)n=50 and DCIS with microinvasionn=28. MR features were correlated with histopathologic findings. Results: Enhancement in DCIS was focal (73%), diffuse (10%) or ductal (17%). No enhancement occurred in two cases (4%). In 65% enhancement speed was classified as delayed. There was a tendency toward a more ill-defined (83 vs. 43%) enhancement pattern in high grade DCIS and a more ductal (29 vs. 12%) and faster (50 vs. 29%) enhancement in comedo type DCIS. However, significant differences in the enhancement behaviour could neither be demonstrated between high grade and non high grade DCIS nor between comedo and non comedo type DCIS. No significant differences were noted between pure and microinvasive DCIS. Conclusion: In this retrospective analysis the majority (96%) of DCIS lesions show contrast enhancement. However, in only about 50% of DCIS the criteria of a so-called ‘typical’ enhancement behaviour was fulfilled, that means strong, early, focal ill-circumscribed or ductal. Enhancement that follows a duct is often associated with malignancy, however this feature was only present in 17% of the cases. c.-e. MR imaging allowed the detection of 25 additional foci of DCIS. Therefore malignant in situ lesions can be present with atypical enhancement, and should be taken into consideration in high-risk patients in particular.     

Dynamic contrast-enhanced MR imaging of the entire breast with spectral-selective inversion fast three dimensional sequence

Dynamic contrast-enhanced images with high spatial and temporal resolutions were acquired with a fast 3D spoiled gradient echo (SPGR) sequence using spectral selective inversion recovery (IR) pulse. Five healthy volunteers and 12 patients with 14 pathologically proven breast lesions were studied. Fat suppressed volume image data covering the entire breast were obtained with a sufficient spatial resolution (0.9×1.5×3.0 mm³) and an imaging time of 57 s. By using the criteria including peripheral enhancement and presence of spiculation, sensitivity, specificity, and accuracy in detecting malignant lesions were 88.9, 80.0 and 85.%, respectively. Although the C/N and S/N ratios were approximately 30% less than those of the conventional fat suppressed 3D technique, fast 3D SPGR imaging with spectral IR method demonstrated sufficient image quality for both time intensity analysis and morphological evaluation of the breast lesions with a data acquisition time less than half of the conventional method. This technique can substantially improve spatial and temporal resolutions of dynamic MR images of the breast and will be useful in evaluating malignant and benign breast lesions.     

Real-time imaging and triggering of 3D contrast-enhanced MR angiograms using MR fluoroscopy

Although a variety of timing techniques and data acquisition strategies have been, used for three-dimensional contrast-enhanced MR angiography, many are still limited by inadequate overall reliability, limited spatial resolution, or complexity. A technique is presented in this work in which contrast arrival is detected in the targeted vasculature in real time using MR fluoroscopy. Upon detection the operator triggers a 3D MR angiographic acquisition which uses an elliptical centric view order. It is shown that the view order intrinsically provides a high degree of venous suppression which in turn allows acquisition times of 30 s or longer. permitting high spatial resolution. The reliability of fluoroscopic triggering in bolus detection is shown to be over 90%. The technique provides high quality contrast-enhanced MR angiograms for many vascular regions.     

Assessment of myocardial perfusion using contrast-enhanced MR imaging: Current status and future developments

Excellent inherent tissue contrast is one of the great promises of clinical magnetic resonance (MR) imaging, but functional information is relatively limited. However, MR imaging complemented by the administration of contrast agents can provide such functional assessment. The perfusion status of the myocardium is one of the most important functional information in cardiovascular imaging. Because the clinical acceptance of a contrast agent is measured by its ability to improve patient outcome and to guide therapy, it is unlikely that detection of myocardial infarction, the final stage of ischemic heart disease, should be the target for contrast media development. It would obviously be better if occult regional myocardial perfusion deficits could be reliably detected. The current article was prepared to help the clinical radiologist to keep pace with new strategies for myocardial enhancement and their potential clinical applicability for detection of early perfusion deficits. Several techniques for noninvasive measurement of myocardial perfusion are currently evolving which have the potential to be introduced into routine MR imaging. Most investigators favor a first-pass analysis of the contrast agent bolus through the myocardium using ultrafast sequences. However, such a technique may require clinical introduction of a blood pool agent. There are good resons to favorT ₁-weighted sequences over susceptibility imaging in such first-pass studies. In the future, assessment of myocardial perfusion status using contrast-enhanced MR imaging may be done producing perfusion maps with high spatial resolution (e.g., 256×128), with sequences available on most scanners without special hardware requirements (e.g., IR-Turboflash, keyhole imaging), and requiring only a short period of time for examination (≈3 min).     

MR perfusion imaging: correlation with PET and quantitative angiography

4. Conclusions The presented MR approach reliably identifies patients with anatomically and hemodynamically signiticant coronary artery stenoses. This is due to the fact, that the pulse sequence used produces a substantial change in signal intensity in the perfused versus poorly perfused myocardial regions. Analysis of upslope in this setting rather than of other parameters provides a very sensitive and specific measure of myocardial ischemia. As upslope is a semiquantitative measure of absolute perfusion, even patients with triple vessel disease may be evaluated using this method. This is not the case when using conventional nuclear techniques. Furthermore, the spatial resolution of the MR images permits one to resolve the subendocardial layers of the myocardium, which thus can be evaluated separately from the entire wall. Again, this is not possible using nuclear cardiology perfusion imaging. The robustness of this MR perfusion imaging approach and the fact, that most of the heart can be covered may qualify for its clinical application in the management of coronary artery disease.     

Ultra-high-field MR in Prostate cancer: Feasibility and Potential

Magnetic Resonance Materials in Physics, Biology and Medicine - Multiparametric MRI of the prostate at clinical magnetic field strengths (1.5/3 Tesla) has emerged as a reliable noninvasive imaging...     

Whole-brain 3D MR fingerprinting brain imaging: clinical validation and feasibility to patients with meningioma

Magnetic Resonance Materials in Physics, Biology and Medicine - MR fingerprinting (MRF) is a MR technique that allows assessment of tissue relaxation times. The purpose of this study is to evaluate...     

MR imaging of focal liver lesions: comparison between turbo spin-echo and conventional spin-echo pulse sequences

The aim of this study was to compare conventional spin-echo (CSE)T ₂-weighted (T2W) images with turbo spin-echo (TSE) T2W pulse sequences in their ability to detect focal liver lesions. Seventy-eight consecutive patients with focal liver lesions were entered into this study. All patients were imaged using the gradient-echo (GE) sequence with the breath-hold technique forT ₁-weighted (T1W) images, and CSE and TSE sequences for T2W images. Qualitative evaluation included lesion detection (number of lesions detected) and conspicuity (extent of visualization of lesional borders); quantitative evaluation included the signal-to-noise (S/N) ratio and the contrast-to-noise (C/N) ratio. TSE showed the best performance in terms of lesion detection; however, the difference between TSE and CSE was significant only in the case of benign cysts (p<0.01). Conspicuity was higher with TSE and CSE, and lower with GE. The S/N and C/N ratios of the two T2W sequences were also comparable, and better than those of GE. However, the combined use of GE and TSE resulted in improved lesion detection. The results show that, because the acquisition time is greatly reduced with TSE sequences, these should be considered as first-line approach to magnetic resonance imaging of the liver for the study of focal lesions.     

In vivo MRS of locally advanced breast cancer: characteristics related to negative or positive choline detection and early monitoring of treatment response

Object  

To explore factors determining the detection of total choline (tCho) by in vivo MR spectroscopy (MRS) in locally advanced breast cancer and to evaluate the ability of in vivo tCho to predict treatment response after one cycle of neoadjuvant chemotherapy (NAC).     

镍电极在充放电过程中的XRD原位观测

Ｎｉ（ＯＨ）２在不同的充放电条件下会发生多种晶型转变,这些变化与ＭＨ－Ｎｉ电池的性能有关。尤其是过充或大电流充电时生成的γ－ＮｉＯＯＨ可造成镍电极膨胀、开裂甚至失效,严重影响镍氢电池使用寿命。由于γ－ＮｉＯＯＨ不稳定,易自放电,常规研究方法很难定量考察充电过程中生成γ－ＮｉＯＯＨ的准确数量。Ｘ射线衍射原位测量技术可有效地在充放电过程中对氢氧化镍正极结构变化进行观测。本文采用该实验技术对氢氧化镍正极活性物质结构变化进行了动态研究。研究表明Ｎｉ（ＯＨ）２晶格缺陷和晶体结构无序化导致Ｘ射线衍射（ＸＲＤ）谱线宽化,具有ＸＲＤ谱线宽化特别是（１０１）谱线宽化特征的镍正极有较高的电化学活性。添加ＺｎＯ可抑制充电时生成γ－ＮｉＯＯＨ的数量,并运用ＸＲＤ定量分析γ－ＮｉＯＯＨ含量的方法计算了此时镍电极在充电状态下γ／（γ＋β）的比值为１４．２％。     

Fatty metaplasia quantification and impact on regional myocardial function as assessed by advanced cardiac MR imaging

Objective

This study aimed to investigate the advantages of recently developed cardiac imaging techniques of fat–water separation and feature tracking to characterize better individuals with chronic myocardial infarction (MI).

Materials and methods

Twenty patients who had a previous MI underwent CMR imaging. The study protocol included routine cine and late gadolinium enhancement (LGE) technique. In addition, mDixon LGE imaging was performed in every patient. Left ventricular (LV) circumferential (Ecc_LV) and radial (Err_LV) strain were calculated using dedicated software (CMR⁴², Circle, Calgary, Canada). The extent of global scar was measured in LGE and fat–water separated images to compare conventional and recent CMR imaging techniques.

Results

The infarct size derived from conventional LGE and fat–water separated images was similar. However, detection of lipomatous metaplasia was only possible with mDixon imaging. Subjects with fat deposition demonstrated a significantly smaller percentage of fibrosis than those without fat (10.68 ± 5.07% vs. 13.83 ± 6.30%; p = 0.005). There was no significant difference in Ecc_LV or Err_LV between myocardial segments containing fibrosis only and fibrosis with fat. However, Ecc_LV and Err_LV values were significantly higher in myocardial segments adjacent to fibrosis with fat deposition than in those adjacent to LGE only.

Conclusions

Advanced CMR imaging ensures more detailed tissue characterization in patients with chronic MI without a relevant increase in imaging and post-processing time. Fatty metaplasia may influence regional myocardial deformation especially in the myocardial segments adjacent to scar tissue. A simplified and shortened myocardial viability CMR protocol might be useful to better characterize and stratify patients with chronic MI.

     

Combined 1H and 31P MR spectroscopic imaging: impaired energy metabolism in severe carotid stenosis and changes upon treatment

OBJECT: To evaluate if combined (1)H and (31)P MR spectroscopic imaging (MRSI) before and after treatment of severe internal carotid artery (ICA) stenosis detects significant changes in energy metabolism in the basal ganglia of both hemispheres. MATERIALS AND METHODS: A group of 14 patients with high-grade ICA stenosis and 11 healthy control subjects were examined with 2D (1)H MRSI and 3D (31)P MRSI at 3 T before and after treatment of severe ICA stenosis. Spectroscopic data were processed with LCModel and jMRUI software. Changes of the phosphorylated metabolites, pH, N-acetyl-acetate, creatine and choline-containing compounds prior/post intervention were analyzed and patients' data were compared with that of control subjects. RESULTS: Untreated patients had significantly higher Adenosindiphosphate (ADP) in basal ganglia ipsi- and contralateral to the side of ACI stenosis compared to controls. After treatment, ADP of both hemispheres significantly decreased by approximately 20% compared to the pre-treatment values. Further, significant decreases of phosphorylated metabolites prior/post intervention were found for patients compared to controls. CONCLUSION: This spectroscopic study reveals that unilateral high-grade ICA stenosis has an effect on cerebral high-energy metabolism of both hemispheres, which is at least partially reversible after treatment. Therefore the restoration of blood flow in high-grade ICA stenosis recovers the impaired energy balance of the brain.     

Optimized in-phase and opposed-phase MR imaging for accurate detection of small fat or water fractions: theoretical considerations and experimental application in emulsions

Object  

To optimize strategies and measurement parameters for quantification of small fat and water fractions (<10%) in mixtures of both components by 4-point in-phase and opposed-phase gradient-echo imaging and to compare theoretical results with in-vitro experiments using emulsions.     

Quantitative in vivo 23Na MR imaging of the healthy human kidney: determination of physiological ranges at 3.0T with comparison to DWI and BOLD

Objectives

The purpose of this prospective study was to assess the normal physiologic ranges of the renal corticomedullary ²³Na-concentration ([²³Na]) gradient at 3.0T in healthy volunteers. The corticomedullary [²³Na] gradient was correlated with other functional MR imaging parameters—blood oxygenation level dependent (BOLD) and diffusion-weighted imaging (DWI)—and to individual and physiologic parameters—age, gender, estimated glomerular filtration rate (eGFR), body mass index (BMI), and blood serum sodium concentration ([²³Na]_serum).

Methods and materials

50 healthy volunteers (30 m, 20 w; mean age: 29.2 years) were included in this IRB-approved study, without a specific a priori preparation in regard to water or food intake. For ²³Na-imaging a 3D density adapted, radial gradient echo (GRE)-sequence (spatial resolution = 5 × 5 × 5 mm³) was used in combination with a dedicated ²³Na-coil and ²³Na-reference phantoms. [²³Na] values of the corticomedullary [²³Na] gradient were measured by placement of a linear region of interest (20 × 1 mm²) from the renal cortex in the direction of the renal medulla. By using external standard reference phantoms, [²³Na] was calculated in mmol/L of wet tissue volume (mmol/l WTV). Axial diffusion-weighted images (spatial resolution = 1.7 × 1.7 × 5.0 mm³) and 2D GRE BOLD images (spatial resolution = 1.2 × 1.2 × 4.0 mm³) were acquired. Mean values ± standard deviations for [²³Na], apparent diffusion coefficient (ADC) values, and R2* values were computed for each volunteer. The corticomedullary ²³Na-concentration gradient (in mmol/l/mm) was calculated along the area of linear concentration increase from the cortex in the direction of the medulla. Correlations between the [²³Na] and DWI, BOLD, and the physiologic parameters were assessed with Pearson correlation coefficients.

Results

The mean corticomedullary [²³Na] for all healthy volunteers increased from the renal cortex (58 ± 17 mmol/l WTV) in the direction of the medulla (99 ± 18 mmol/l WTV). The inter-individual differences ranged from respective cortical and medullary values of 27 and 63 mmol/L WTV to 126 and 187 mmol/L WTV. No statistically significant differences in renal [²³Na] were found based on differences in individual or physiologic parameters (age, gender, [²³Na]_serum, BMI, GFR). No ADC or R2* gradients were identified, and [²³Na] did not correlate with these parameters.

Conclusion

Renal corticomedullary [²³Na] values increase from the cortex in the direction of the medullary pyramid, demonstrating wide inter-individual ranges and no significant correlations with age, gender, [²³Na]_serum, BMI, GFR, ADC, or R2* values. For future clinical evaluations, an approach relying on renal stimulation (e.g. pharmacologically induced diuresis) may be applicable to account for wide inter-individual ranges of normal [²³Na].     

Quantitative effects of acquisition duration and temporal resolution on the measurement accuracy of prostate dynamic contrast-enhanced MRI data: a phantom study

Objectives

The aim of this study was to investigate the effect of the temporal resolution (T _res) and acquisition duration (AD) on the measurement accuracy of contrast concentration–time curves (CTCs), and derived phenomenological and pharmacokinetic parameter values, in a dynamic contrast-enhanced MRI experiment using a novel phantom test device.

Materials and methods

‘Ground truth’ CTCs were established using a highly precise optical imaging system. These precisely known CTCs were produced in an anthropomorphic environment, which mimicked the male pelvic region, and presented to the MRI scanner for measurement. The T _res was varied in the range [2–24.4 s] and the AD in the range [30–600 s], and the effects on the measurement accuracy were quantified.

Results

For wash-in parameter measurements, large underestimation errors (up to 40%) were found using T _res values ≥16.3 s; however, the measured wash-out rate did not vary greatly across all T _res values tested. Errors in derived K ^trans and v _e values were below 14 and 12% for acquisitions with {T _res ≤ 8.1 s, AD ≥ 360 s} and {T _res ≤ 16.3 s, AD ≥ 360 s}, respectively, but increased dramatically outside these ranges.

Conclusions

Errors in measured wash-in, wash-out, K ^trans, and v _e parameters were minimised using T _res ≤ 8.1 s and AD ≥ 360 s, with large errors recorded outside of this range.

     

2D and 3D texture analysis to differentiate brain metastases on MR images: proceed with caution

Objective

To find structural differences between brain metastases of lung and breast cancer, computing their heterogeneity parameters by means of both 2D and 3D texture analysis (TA).

Materials and methods

Patients with 58 brain metastases from breast (26) and lung cancer (32) were examined by MR imaging. Brain lesions were manually delineated by 2D ROIs on the slices of contrast-enhanced T1-weighted (CET1) images, and local binary patterns (LBP) maps were created from each region. Histogram-based (minimum, maximum, mean, standard deviation, and variance), and co-occurrence matrix-based (contrast, correlation, energy, entropy, and homogeneity) 2D, weighted average of the 2D slices, and true 3D TA were obtained on the CET1 images and LBP maps.

Results

For LBP maps and 2D TA contrast, correlation, energy, and homogeneity were identified as statistically different heterogeneity parameters (SDHPs) between lung and breast metastasis. The weighted 3D TA identified entropy as an additional SDHP. Only two texture indexes (TI) were significantly different with true 3D TA: entropy and energy. All these TIs discriminated between the two tumor types significantly by ROC analysis. For the CET1 images there was no SDHP at all by 3D TA.

Conclusion

Our results indicate that the used textural analysis methods may help with discriminating between brain metastases of different primary tumors.

     

Detection of glioblastoma multiforme using quantitative molecular magnetic resonance imaging based on 5-aminolevulinic acid: in vitro and in vivo studies

Magnetic Resonance Materials in Physics, Biology and Medicine - We demonstrated a novel metabolic method based on sequential administration of 5-aminolevulinic acid (ALA) and iron supplement, and...