Michael T. Nelson

In vivo quantification of choline compounds in the breast with 1H MR spectroscopy.

This work describes a methodology for quantifying levels of total choline‐containing compounds (tCho) in the breast using in vivo 1H MR spectroscopy (MRS) at high field (4 Tesla). Water is used as an internal reference compound to account for the partial volume of adipose tissue. Peak amplitudes are estimated by fitting one peak at a time over a narrow frequency band to allow measurement of small metabolite resonances in spectra with large lipid peaks. This quantitative method significantly improves previously reported analysis methods by accounting for the variable sensitivity of breast 1H MRS measurements. Using this technique, we detected and quantified a tCho peak in 214 of 500 in vivo spectra. tCho levels were found to be significantly higher in malignancies than in benign abnormalities and normal breast tissues, which suggests that this technique could be used to diagnose suspicious lesions and monitor response to cancer treatments. Magn Reson Med 50:1134–1143, 2003.

Imaging in breast cancer: Magnetic resonance spectroscopy

A technique called in vivo magnetic resonance spectroscopy (MRS) can be performed along with magnetic resonance imaging (MRI) to obtain information about the chemical content of breast lesions. This information can be used for several clinical applications, such as monitoring the response to cancer therapies and improving the accuracy of lesion diagnosis. Initial MRS studies of breast cancer show promising results, and a growing number of research groups are incorporating the technique into their breast MRI protocols. This article introduces 1H-MRS of the breast, reviews the literature, discusses current methods and technical issues, and describes applications for treatment monitoring and lesion diagnosis.

MR spectroscopy of breast cancer for assessing early treatment response: Results from the ACRIN 6657 MRS trial

To estimate the accuracy of predicting response to neoadjuvant chemotherapy (NACT) in patients with locally advanced breast cancer using MR spectroscopy (MRS) measurements made very early in treatment.

Feasibility of single-voxel MRS measurement of apparent diffusion coefficient of water in breast tumors.

We report initial results with single voxel spectroscopy (SVS) using diffusion weighting and localization by adiabatic selective refocusing (LASER) in breast tumors to measure the apparent diffusion coefficient of water (ADCw). This is a quick (30 s) and relatively easy method to implement compared with image‐based diffusion measurements, and is insensitive to lipid signal contamination. The ADCw and concentration of total choline containing compounds [tCho] were evaluated for associations with each other and final pathologic diagnosis in 25 subjects. The average (± SD) ADCw in benign and malignant lesions was 1.96 ± 0.47 mm2/s and 1.26 ± 0.29 × 10−3 mm2/s, respectively, P< 0.001. Receiver operating characteristic curve analysis showed an area under the curve of 0.92. Analysis of the single voxel (SV) ADCw and [tCho] showed significant correlation with a R2 of 0.56, P< 0.001. Compared with more commonly used image‐based methods of measuring water ADC, SV‐ADCw is faster, more robust, insensitive to fat, and potentially easier to implement on standard clinical systems. Magn Reson Med, 2009.

High-Spatial- and High-Temporal-Resolution Dynamic Contrast-enhanced MR Breast Imaging with Sweep Imaging with Fourier Transformation: A Pilot Study

PURPOSE To report the results of sweep imaging with Fourier transformation (SWIFT) magnetic resonance (MR) imaging for diagnostic breast imaging. MATERIALS AND METHODS Informed consent was obtained from all participants under one of two institutional review board-approved, HIPAA-compliant protocols. Twelve female patients (age range, 19-54 years; mean age, 41.2 years) and eight normal control subjects (age range, 22-56 years; mean age, 43.2 years) enrolled and completed the study from January 28, 2011, to March 5, 2013. Patients had previous lesions that were Breast Imaging Reporting and Data System 4 and 5 based on mammography and/or ultrasonographic imaging. Contrast-enhanced SWIFT imaging was completed by using a 4-T research MR imaging system. Noncontrast studies were completed in the normal control subjects. One of two sized single-breast SWIFT-compatible transceiver coils was used for nine patients and five controls. Three patients and five control subjects used a SWIFT-compatible dual breast coil. Temporal resolution was 5.9-7.5 seconds. Spatial resolution was 1.00 mm isotropic, with later examinations at 0.67 mm isotropic, and dual breast at 1.00 mm or 0.75 mm isotropic resolution. RESULTS Two nonblinded breast radiologists reported SWIFT image findings of normal breast tissue, benign fibroadenomas (six of six lesions), and malignant lesions (10 of 12 lesions) concordant with other imaging modalities and pathologic reports. Two lesions in two patients were not visualized because of coil field of view. The images yielded by SWIFT showed the presence and extent of known breast lesions. CONCLUSION The SWIFT technique could become an important addition to breast imaging modalities because it provides high spatial resolution at all points during the dynamic contrast-enhanced examination.

Breast MRI using SWeep Imaging with Fourier Transform (SWIFT)

SWIFT [1] (SWeep Imaging with Fourier Transform) is a radially sampled magnetic resonance imaging (MRI) sequence utilizing gapped frequency-swept pulse excitation with nearly simultaneou signal acquisition between pulse elements. There is no “echo time” so signal is nearly always being acquired making SWIFT fast and efficient. High temporal and spatial resolution is obtainable from the same scan data. Rapid imaging capability as well as T2* insensitivity make SWIFT desirable for dynamic contrast enhancement. The novel properties of SWIFT may be utilized clinically to advance breast MR imaging.

What is new in breast MRI spectroscopy.

A review of breast spectroscopy and its metabolite imaging – MRS is useful for clinical evaluation in neoadjuvant chemotherapy for the treatment of breast cancer. Why has it not been implemented on all clinical breast MRI scanners? Doing MRI/MRS on smaller breast cancers is difficult and cannot be done on breast cancers less than 6mm × 6mm × 6mm. High field magnets are used in single voxel spectroscopy (laser) for beast quantitative results (3T or 4T). The MRI/MRS latest results from I-SPY I (NIH/ACRIN) are not yet published for the multi-centered trial. Also having to shim the magnet and preset sequences for optimizing MRS has been an issue and requires a MRI physicist to do these studies. Choline measurements on 1.5T magnets that are shimmed well can detect choline within a large tumor (>2–3 cm). However, it is difficult to quantitate the choline with the breast cancer using 1.5T magnets. The results from the first MRS trial at the University of Minnesota Center for Magnetic Resonance Research will be published at the San Antonio Breast Meeting (December 2012). The report will be on 60 MRI/MRS cases and 5 year survival data. MRI/MRS neoadjuvant breast cancer imaging can be evaluated by three MRI methods to get to the RECIST evaluation: (1) L/D – longest diameter; (2) MRS – metabolite imaging and (3) Volume imaging of contrast (3D). All these methods have difficulty with non-mass like tumors. Making objective measurements of changes in breast tumor size can be challenging. The spectrum of breast tumor morphology and appearance on MRI creates difficulty generating accurate objective measurements which is used by oncology RECIST criteria to track tumor response in breast cancer. Depending on morphology and enhancement of an individual lesion an objective LD comparison may be problematic as seen in the following abstract. Inter-observer agreement in assessment of breast cancer response to neoadjuvant chemotherapy on MRI: Qualitative versus quantitative evaluation (11/28/11 RSNA, Chicago, IL). Volume Imaging: MRI tumor volume for predicting response to neoadjuvant chemotherapy in locally advanced breast cancer: findings from ACRIN 6657/calgb 15007 (2009 Asco) Noxla Hilton. Tumor response measured volumetrically by MRI is a stronger and earlier predictor of pathologic response after (NACT) than clinical exam or tumor diameter. Volumetric MRI imaging must use accurate volume (3D) placement of a voxel under MRI guidance. This procedure is not yet automated and must be completed by an experienced MRI radiologist. If the clinical trial shows that the pathologic response is very good (in 1–2 weeks) then this test may not be as sensitive for predicting (NACT) response. (Chemotherapy drugs work extremely well and the tumor decreases gadolinium uptake to zero.)

Repeatability of Respiratory Exchange Ratio Time Series Analysis.

Abstract Nelson, MT, Biltz, GR, and Dengel, DR. Repeatability of respiratory exchange ratio time series analysis. J Strength Cond Res 29(9): 2550–2558, 2015—Currently, there are few studies on the repeatability of a time series analysis of respiratory exchange ratio (RER) under the same conditions. This repeated-measures study compared 2 trials completed under the same conditions. After an 8-hour fast, subjects (7 male and 5 female) (mean ± SD) of age 27.3 ± 3.7 years, body weight of 71.8 ± 8.4 kg, percent body fat of 16.4 ± 8.1%, and peak oxygen uptake (V[Combining Dot Above]O2peak) of 46.0 ± 5.3 ml·kg−1·min−1 completed a V[Combining Dot Above]O2peak test followed 7 days later by a cycle ergometer test at 30% of ventilatory threshold (VT) and 60% of VT for 15 minutes each. These tests were repeated again 7 days later. Paired t-tests revealed no significant differences between the tests for mean RER or sample entropy (SampEn) score at both intensities. The coefficients of variance were generally similar for the mean and SampEn of the RER. The intraclass correlation coefficient (ICC) values for the mean RER at 30% of VT were 1.00 and at 60% of VT were 0.92. The ICC values for the SampEn RER at 30% of VT were 0.81 and at 60% of VT were the lowest at 0.25. Bland-Altman plots demonstrated a measure of agreement between both methods. We demonstrated that RER measurements at 30 and 60% of VT are repeatable during steady-state cycle ergometery. Future research should determine if this finding is consistent with a larger sample size and different exercise intensities.

Using magnetic resonance to diagnose breast cancer and predict therapeutic response

Neoplastic tissue contains elevated levels of choline-containing metabolites (tCho) [1,2]. The purpose of this study is to determine whether magnetic resonance spectroscopy (MRS) with magnetic resonance imaging (MRI) can be a noninvasive technique for determining whether a breast abnormality is benign or malignant and to monitor response to neoadjuvant chemotherapy (CT).

Digital Magnification Mammography

A CCD camera consisting of a phosphor screen, fiber optic reducer and charge coupled device. With an imaging area of 24.6 mm × 24.6 mm with 1024 × 1024 pixels was used to examine breast masses less than 2 cm found on film screen mammography.