A prospective study was undertaken in women undergoing neoadjuvant chemotherapy for locally advanced breast cancer in order to determine the ability of quantitative magnetic resonance imaging (MRI) and proton spectroscopy (MRS) to predict ultimate tumour response (percentage decrease in volume) or to detect early response. Magnetic resonance imaging and MRS were carried out before treatment and after the second of six treatment cycles. Pharmacokinetic parameters were derived from T 1 -weighted dynamic contrast-enhanced MRI, water apparent diffusion coefficient (ADC) was measured, and tissue water : fat peak area ratios and water T 2 were measured using unsuppressed one-dimensional proton spectroscopic imaging (30 and 135 ms echo times). Pharmacokinetic parameters and ADC did not detect early response; however, early changes in water : fat ratios and water T 2 (after cycle two) demonstrated substantial prognostic efficacy. Larger decreases in water T 2 accurately predicted final volume response in 69% of cases (11/16) while maintaining 100% specificity and positive predictive value. Small/absent decreases in water : fat ratios accurately predicted final volume non-response in 50% of cases (3/6) while maintaining 100% sensitivity and negative predictive value. This level of accuracy might permit clinical application where early, accurate prediction of non-response would permit an early change to second-line treatment, thus sparing patients unnecessary toxicity, psychological morbidity and delay of initiation of effective treatment.

Neoadjuvant chemotherapy has become the standard treatment for patients with locally advanced breast cancer; however a technique that can accurately differentiate responders from non-responders at an early time point during treatment has still to be identified. The purpose of this work was to evaluate the ability of pharmacokinetically modelled dynamic contrast-enhanced MRI data to predict and monitor response of patients diagnosed with locally advanced breast cancer to neoadjuvant chemotherapy, at an early time point during treatment. Sixty-eight patients with histology proven breast cancer underwent MRI examination prior to treatment, early during treatment and following the final cycle of chemotherapy. A two compartment pharmacokinetic model provided the kinetic parameters transfer constant (Ktrans), rate constant (Kep) and extracellular extravascular space (Ve) for a region of interest encompassing the whole lesion (ROIwhole) and a 3x3 pixel 'hot-spot' showing the greatest mean maximum percentage enhancement from within that region (ROIhs). Following treatment 48 patients were classified as responders and 20 as non-responders based on total tumour volume reduction. Tumour volume changes between the pre-treatment and early treatment time points demonstrated differences between responders and non-responders with percentage change revealing the most significant result (p<0.001). Analysis based on ROIhs provided more statistically significant differences between responders and non-responders then ROIwhole analysis. ROIhs analysis demonstrated differences between responders and non-responders both prior to and early during treatment. A highly significant reduction in both Ktrans and Kep (p<0.001) was noted for responders between the pre-treatment and early treatment time points, while Ve significantly increased during the same time period for non-responders (p<0.001). Quantification of dynamic contrast enhancement parameters provides a potential means for differentiating responders from non-responders early during their treatment, thereby allowing a prompt change in treatment if necessary.

Purpose:To evaluate the efficacy of MR Spectroscopy (MRS) at 3.0 Tesla for the assessment of normal bone marrow composition and assess the variation in terms of age, gender, and skeletal site. Materials and Methods:A total of 16 normal subjects (aged between eight and 57 years) were investigated on a 3.0 Tesla GE Signa system. To investigate axial and peripheral skeleton differences, non-water-suppressed spectra were acquired from single voxels in the calcaneus and lumbar spine. In addition, spectra were acquired at multiple vertebral bodies to assess variation within the lumbar spine. Data was also correlated with bone mineral density (BMD) measured in six subjects using dual-energy X-ray absorptiometry (DXA). Results:Fat content was an order of magnitude greater in the heel compared to the spine. An age-related increase was demonstrated in the spine with values greater in men compared to female subjects. Significant trends in vertebral bodies within the same subjects were also shown, with fat content increasing L5 Ͼ L1. Population coefficient of variation (CV) was greater for fat fraction (FF) compared to BMD. Conclusion:Significant normal variations of marrow composition have been demonstrated, which provide important data for the future interpretation of patient investigations.

Purpose:To compare different imaging methods with single-voxel MR spectroscopy (MRS) for the quantification of fat content in phantoms at 3.0T. Materials and Methods:Imaging and spectroscopy was performed on a GE Signa system. Eleven novel homogeneous fat-water phantoms were constructed with variation in fat content from 0% to 100%. These were imaged using three techniques and compared with single-voxel non-water-suppressed MRS. Pixel-by-pixel maps of fat fraction were produced and mean values compared to MRS-determined measurements. Preliminary in vivo examinations were subsequently performed in the breast and spine to compare the best imaging technique with MRS.Results: All imaging methods significantly correlated with MRS (P Ͻ 0.001): IDEAL (r 2 ϭ 0.985), IOP (r 2 ϭ 0.888), WS (r 2 ϭ 0.939), and FS (r 2 ϭ 0.938). In addition, IDEAL provided artifact-free maps of fat fraction with superior uniformity. In vivo results using IDEAL produced values that were between 9% to 16% of the corresponding MRS values. Conclusion:This work demonstrates that imaging may be utilized as a high-resolution alternative to MRS for the quantification of fat content. In the future we intend to replace MRS with IDEAL in our clinical studies involving fat measurement.