7 T versus 3 T contrast-enhanced breast Magnetic Resonance Imaging of invasive ductulolobular carcinoma: First clinical experience

Purpose

Here we describe our first experience with contrast-enhanced (CE) MRI of breast cancer at 7 tesla (T), compared to 3 T and histopathology.

Materials and Methods

A 52 year old female patient with a mammographically suspicious breast mass (BI-RADS V) underwent 7 T CE-MRI. Results were described according to the BI-RADS-MRI criteria and compared to 3 T and histopathology.

Results

After contrast administration, a homogeneously enhancing, irregular spiculated mass was depicted at both 3 T and 7 T; sizes were identical. The most malignant kinetic curve was characterized by a rapid initial rise followed by a wash-out pattern in the delayed phase, i.e. a type 3 curve, at both field strengths. Even though T1-effects of contrast agents are suggested to be reduced at higher fields, quantification of contrast enhancement-to-noise ratio showed a ratio of 4.6 at 7 T and 2.8 at 3 T when comparing contrast-to-noise of the mass before and after contrast administration. Both examinations, using a single dose of gadolinium-based contrast agent, achieved good image quality. Final histopathological evaluation showed an invasive ductulolobular carcinoma with an intraductal component.

Conclusion

This initial experience suggests that clinical contrast-enhanced 7 T MRI of the breast is technically feasible and may allow BI-RADS-conform analysis.     

General implementation of the ERETIC method for pulsed field gradient probe heads

A capacitive coupling between a secondary radiofrequency (rf) channel and the gradient coil of a standard commercially available high resolution NMR spectrometer and probe head is described and used to introduce a low level exponentially damped rf signal near the frequency of the primary rf channel to serve as an external concentration standard, in analogy to the so-called ERETIC™ method. The stability of this inexpensive and simple to implement method, here referred to as the Pulse Into the Gradient (PIG) approach, is superb over a 14-h period and both gradient tailored water suppression and one-dimensional imaging applications are provided. Since the low level signal is introduced via the pulsed field gradient coil, the coupling is identical to that for a free induction signal and thus the method proves to be immune (within 5%) to sample ionic strength effects up to the 2 M NaCl solutions explored here.     

Near-infrared dyes,nanomaterials and proteins

Taking the advantage of reduced scattering and low autofluorescence background, the NIR fluorescence probes, such as fluorescence proteins, organic molecules and nanoparticles, not only hold the promise of in vivo imaging of biological processes in physiology and pathology with high signal-to-noise ratio, but also for clinical diagnosis. In this review, we provide an overview of the recent progress on NIR probes, focusing on fundamental mechanisms of NIR dyes and nanoparticles, and protein engineering strategies for NIR proteins.     

Nanodiamonds for advanced optical bioimaging and beyond

Nanodiamond (ND) has emerged as an intriguing material in recent years both industrially and in research. During the last decade, ND has furthered its way into the biomedical field, mainly due to its inherent photoluminescent properties. In parallel, the development of advanced biomedical imaging methods and techniques has faced a steep upswing, making these two a ‘perfect match’. The optical and physical properties of ND can be tuned, rendering them highly interesting as versatile biomedical imaging probes. In this short review, we will cover a few of the most recently emerged applications of NDs in biomedical imaging and contemplate on current challenges and future directions.     

Ultrasound simulation of real-time temperature estimation during radiofrequency ablation using finite element models

Radiofrequency ablation is the most common minimally invasive therapy used in the United States to treat hepatocellular carcinoma and liver metastases. The ability to perform real-time temperature imaging while a patient is undergoing ablation therapy may help reduce the high recurrence rates following ablation therapy. Ultrasound echo signals undergo time shifts with increasing temperature due to sound speed and thermal expansion, which are tracked using both 1D cross correlation and 2D block matching based speckle tracking methods. In this paper, we present a quantitative evaluation of the accuracy and precision of temperature estimation using the above algorithms on both simulated and experimental data.A finite element analysis simulation of radiofrequency ablation of hepatic tissue was developed. Finite element analysis provides a method to obtain the exact temperature distribution along with a mapping of the tissue displacement due to thermal expansion. These local displacement maps were combined with the displacement due to speed of sound changes and utilized to generate ultrasound radiofrequency frames at specified time increments over the entire ablation procedure. These echo signals provide an ideal test-bed to evaluate the performance of both speckle tracking methods, since the estimated temperature results can be compared directly to the exact finite element solution. Our results indicate that the 1D cross-correlation (CC) method underestimates the cumulative displacement by 0.20 mm, while the underestimation with 2D block matching (BM) is about 0.14 mm after 360 s of ablation. The 1D method also overestimates the size of the ablated region by 5.4% when compared to 2.4% with the 2D method after 720 s of ablation. Hence 2D block matching provides better tracking of temperature variations when compared to the 1D cross-correlation method over the entire duration of the ablation procedure. In addition, results obtained using 1D cross-correlation diverge from the ideal finite element results after 7 min of ablation and for temperatures greater than 65 °C.In a similar manner, experimental results presented using a tissue-mimicking phantom also demonstrate that the maximum percent difference with 2D block matching was 5%, when compared to 31% with the 1D method over the 700 s heating duration on the phantom.     

Prospective trial of a navigator setting under left hepatic lobe on magnetic resonance cholangiopancreatography using a free-breathing prospective acquisition correction technique

PURPOSE: To prospectively compare the image acquisition time and image quality obtained by navigator setting under the left hepatic lobe vs. on the right diaphragm on magnetic resonance cholangiopancreatography (MRCP) using a free-breathing navigator-triggered prospective acquisition correction technique (PACE). MATERIALS AND METHODS: Fifty consecutive patients prospectively underwent three-dimensional T2-weighted turbo spin-echo MRCP using PACE with the navigator randomly set either under the left hepatic lobe or on top of the right diaphragm. Image acquisition time and subjective image quality were compared on a five-point scale using Student's t-test and Mann-Whitney's U test, respectively. RESULTS: There was no significant difference for mean acquisition time (6.1+/-1.6 vs. 6.3+/-1.2 min, P=.689) between the left hepatic lobe group and right diaphragm group. Mean subjective image quality was significantly worse in the left hepatic lobe group than in the right diaphragm group (4.1 vs. 4.7, P=.044). CONCLUSION: Setting the navigator under the left hepatic lobe for MRCP using PACE causes the data processing to be more difficult. As well, under current circumstances, it does not contribute to reducing acquisition time or improving the image quality.     

Aggregation‐Induced and Polymorphism‐Dependent Thermally Activated Delayed Fluorescence (TADF) Characteristics of an Oligothiophene: Applications in Time‐Dependent Live Cell Multicolour Imaging

Typically, molecules with a twisted donor–acceptor (D‐A) architecture have been exploited for constructing thermally activated delayed fluorescence (TADF) materials. Herein, we report the first example of a thiophene‐based thermally activated delayed fluorescent molecule without a D‐A architecture. Compound 1 (2,5‐bis(2,2‐di(thiophen‐2‐yl)vinyl)thiophene) is conformationally flexible and shows weak fluorescence in the solution state but displays bright TADFin both condensed and solid states. Compound 1 crystallized in two different polymorphs ( 1 a and 1 b ). Interestingly, both polymorphs show distinctly different TADF features. The broad spectral features and the TADF characteristics of 1 have been explored for the time‐dependent multicolor (green, yellow and red) imaging of living cells.     

Synthesis of para‐[18F]Fluorofenbufen Octylamide for PET Imaging of Brain Tumors

Glioma is a brain tumor associated with a poor therapeutic outcome with an average life expectancy of 14 months. Cyclooxygenase‐2 (COX‐2) expression is associated with the progression of the tumor and is considered a therapeutic target of chemo agents. Para‐[¹⁸F]Fluorofenbufen octylamide ([¹⁸F]FFOA) was obtained with the radiochemical yield of 16% and specific activity of 4 GBq/μmol, and the IC₅₀ values of COX‐1 and COX‐2 were 26.5 and 32.7 μM, respectively. The stability of cold FFOA in plasma was significantly improved with a half‐life of 30 min, and the uptake ratio of [¹⁸F]FFOA in rats with brain tumor was 1.5 as determined from accumulation of 3.9% injection dose (ID/g) in the brain tumor and 2.5% ID/g in the brain. [¹⁸F]FFOA with COX‐2 micromolar affinity can be used to differentiate between brain tumor and normal region.     

Granitic groundwater colloids sampling and characterisation: the strategy for artefact elimination

Colloids were separated by submicro-filtration of granitic groundwater samples collected at-line under in-situ thermodynamic conditions after down-hole groundwater sampling and transfer at the well head. The methodology avoids the generation of artefacts produced by pH changes due to CO(2) exchange, yielding potential carbonate precipitation, or by O(2) contamination yielding oxidized insoluble phases. The enhanced pressure and the anoxic conditions are also maintained through the filtering procedure. This procedure was carried out after a period of regular sampling of groundwater pumped to the ground surface and continuous on-line long-term measurements (weeks, months) of chemical and physical parameters in the unbroken sample water both at the ground surface and at depth down-hole. Colloid samples were characterized on the submicro-filtration membrane by scanning electron microscopy. Under deep granite groundwater conditions, natural colloids occur sparsely. The colloid concentration was determined C(col) approximately 1 and approximately 50 microg L(-1) for sizes ranging from 50 to 200 nm or n(col) approximately 3.9 x 10(9) and 47 x 10(9) L(-1) for sizes larger than 50 nm for KFM11A, Forsmark, and KLX17A, Laxemar, Oskarshamn, respectively, Sweden. These colloids are expected to be clay particles with an average size smaller than 200 nm for the Na-Ca-Cl and Na-Cl groundwaters (pH 7.6 and 8.00, ionic strength approximately 10(-1) and approximately 10(-2) mol L(-1), respectively, for KFM11A and KLX17A), the colloid concentrations were comparable with values previously reported in the literature.