Faculty Bibliography

The effective delivery of a therapeutic drug to the core of a tumor is often impeded by physiological barriers, such as the interstitial fluid pressure (IFP). There are a number of therapies that can decrease IFP and induce tumor vascular normalization. However, a lack of a noninvasive means to measure IFP hinders the utilization of such a window of opportunity for the maximization of the treatment response. Thus, the purpose of this study was to investigate the feasibility of using intravoxel incoherent motion (IVIM) diffusion parameters as noninvasive imaging biomarkers for IFP. Mice bearing the 4T1 mammary carcinoma model were studied using diffusion-weighted imaging (DWI), immediately followed by wick-in-needle IFP measurement. Voxelwise analysis was conducted with a conventional monoexponential diffusion model, as well as a biexponential model taking IVIM into account. There was no significant correlation of IFP with either the median apparent diffusion coefficient from the monoexponential model (r = 0.11, p = 0.78) or the median tissue diffusivity from the biexponential model (r = 0.30, p = 0.44). However, IFP was correlated with the median pseudo-diffusivity (D(p) ) of apparent vascular voxels (r = 0.76, p = 0.02) and with the median product of the perfusion fraction and pseudo-diffusivity (f(p) D(p) ) of apparent vascular voxels (r = 0.77, p = 0.02). Although the effect of IVIM in tumors has been reported previously, to our knowledge, this study represents the first direct comparison of IVIM metrics with IFP, with the results supporting the feasibility of the use of IVIM DWI metrics as noninvasive biomarkers for tumor IFP

Objective: To investigate the frequency, imaging features, and surgical outcome of papillary lesions identified at 3-T MRI. Materials and Methods: This HIPAA-compliant institutional review board-approved retrospective study evaluated papillary lesions detected on MRI and sampled with either MR-guided 9-gauge vacuum assisted biopsy (VAB) or ultrasound-guided biopsy from 2008 to 2010. Lesion description, size, BI-RADS category, percutaneous biopsy results (MR-guided, ultrasound-guided, or stereotactic) and any upgrade at final excision were recorded for each lesion. Results: In total, 23 cases of pathology proven MRI-detected papillary lesions were identified in 22 patients. The indication for the initial MR study was a personal history of breast cancer in 13 (59%), a history of high-risk lesions in 2 patients (9%), a history of family history of breast cancer in 1 patient (5%), and other indications in 6 patients (27%). Nine papillary lesions presented as nonmasslike enhancement (NMLE), 13 presented as masses, and one presented as a focus on MR. Eight lesions had a sonographic correlate and were biopsied under ultrasound guidance; of this group, 6 cases were masses and 2 were NMLE. Those lesions with a correlate had a mean size of 1.7 cm, larger than those lesions without a correlate (mean of 1.3 cm), but the difference in means was not statistically significant. Nine of 23 cases (39%) of papillary lesions were in a retroareolar location. Of the 13 masses, 8 cases had irregular margins (62%). No kinetic features were identified more frequently in papillary lesions. In 7 cases (30%), the initial biopsy found additional high risk lesion(s) in association with the papillary finding. Two (8.7%) papillary lesions with associated high-risk lesions were upgraded to DCIS at surgical excision. One of these was found on ultrasound and the other on MR-guided biopsy. There were no cases of an isolated papillary lesion being upgraded to DCIS or invasive carcinoma. Conclusion: Review of the MR findings demons!

OBJECTIVE: Women at high risk for breast cancer and women with newly diagnosed breast cancer often undergo breast MRI. With the increasing availability of MRI-guided biopsy, high-risk lesions are not infrequently encountered. These high-risk lesions include atypical ductal hyperplasia, lobular carcinoma in situ, atypical lobular hyperplasia, papilloma, radial scar, and flat epithelial cell atypia. The management of these lesions is controversial and is often extended to high-risk lesions detected on mammography and ultrasound, with surgical excision usually recommended. The increasing use of MRI for suspicious lesions necessitates review of the imaging characteristics, frequency, and surgical outcome of high-risk lesions identified at MRI. This article addresses the frequency of high-risk lesions detected on breast MRI according to the current literature and discusses MRI features of high-risk lesions, including morphologic and enhancement kinetic characteristics. The surgical outcome for high-risk lesions identified at MRI-guided biopsy will be discussed. Finally, appropriate management guidelines for high-risk lesions identified on MRI-guided biopsy will be determined. CONCLUSION: To our knowledge, no studies to date show definitive and specific characteristics for high-risk lesions. Underestimation of malignancy on MRI-guided biopsy currently warrants surgical management for all high-risk lesions. There is a need for prospective larger power studies

Diffusion-weighted imaging plays important roles in cancer diagnosis, monitoring, and treatment. Although most applications measure restricted diffusion by tumor cellularity, diffusion-weighted imaging is also sensitive to vascularity through the intravoxel incoherent motion effect. Hypervascularity can confound apparent diffusion coefficient measurements in breast cancer. We acquired multiple b-value diffusion-weighted imaging at 3 T in a cohort of breast cancer patients and performed biexponential intravoxel incoherent motion analysis to extract tissue diffusivity (D(t) ), perfusion fraction (f(p) ), and pseudodiffusivity (D(p) ). Results indicated significant differences between normal fibroglandular tissue and malignant lesions in apparent diffusion coefficient mean (+/-standard deviation) values (2.44 +/- 0.30 vs. 1.34 +/- 0.39 mum(2) /msec, P < 0.01) and D(t) (2.36 +/- 0.38 vs. 1.15 +/- 0.35 mum(2) /msec, P < 0.01). Lesion diffusion-weighted imaging signals demonstrated biexponential character in comparison to monoexponential normal tissue. There is some differentiation of lesion subtypes (invasive ductal carcinoma vs. other malignant lesions) with f(p) (10.5 +/- 5.0% vs. 6.9 +/- 2.9%, P = 0.06), but less so with D(t) (1.14 +/- 0.32 mum(2) /msec vs. 1.18 +/- 0.52 mum(2) /msec, P = 0.88) and D(p) (14.9 +/- 11.4 mum(2) /msec vs. 16.1 +/- 5.7 mum(2) /msec, P = 0.75). Comparison of intravoxel incoherent motion biomarkers with contrast enhancement suggests moderate correlations. These results suggest the potential of intravoxel incoherent motion vascular and cellular biomarkers for initial grading, progression monitoring, or treatment assessment of breast tumors. Magn Reson Med, 2011. (c) 2011 Wiley-Liss, Inc

The purpose of this study is to report further about the statistically significant results from a prospective study, which suggests that fusion of prone F-18 Fluoro-deoxy-glucose (FDG) positron emission tomography (PET) and magnetic resonance (MR) breast scans increases the positive predictive value (PPV) and specificity for patients in whom the MR outcome alone would be nonspecific. Thirty-six women (mean age, 43 years; range, 24-65 years) with 90 lesions detected on MR consented to undergo a FDG-PET scan. Two blinded readers evaluated the MR and the computer tomography (CT) attenuation-corrected prone FDG-PET scans side-by-side, then after the volumes were superimposed (fused). A semiautomatic, landmark-based program was used to perform nonrigid fusion. Pathology and radiologic follow-up were used as the reference standard. The sensitivity, specificity, PPV, negative predictive value (NPV), and accuracy (with 95% confidence intervals) for MR alone, FDG-PET alone, and fused MR and FDG-PET were calculated. The median lesion size measured from the MR was 2.5 cm (range, 0.5-10 cm). Histologically, 56 lesions were malignant, and 15 were benign. Nineteen lesions were benign after 20-47 months of clinical and radiologic surveillance. The sensitivity of MR alone was 95%, FDG-PET alone was 57%, and fusion was 83%. The increase in PPV from 77% in MR alone to 98% when fused and the increase in specificity from 53% to 97% were statistically significant (p < 0.05). The false-negative rate on FDG-PET alone was 26.7%, and after fusion this number was reduced to 9%. FDG-PET and MR fusions were helpful in selecting which lesion to biopsy, especially in women with multiple suspicious MR breast lesions

The technical requirements for magnetic resonance imaging (MRI) of the breasts are challenging because high temporal and high spatial resolution are necessary. This article describes the necessary equipment and pulse sequences for performing a high-quality study. Although imaging at 3-Tesla (T) has a higher signal-to-noise ratio, the protocol needs to be modified from the 1.5-T system to provide optimal imaging. The article presents the requirements for performing breast MRI and discusses techniques to ensure high-quality examinations on 1.5-T and 3-T systems

For many supervised learning tasks it may be infeasible (or very expensive) to obtain objective and reliable labels. Instead, we can collect subjective (possibly noisy) labels from multiple experts or annotators. In practice, there is a substantial amount of disagreement among the annotators, and hence it is of great practical interest to address conventional supervised learning problems in this scenario. In this paper we describe a probabilistic approach for supervised learning when we have multiple annotators providing (possibly noisy) labels but no absolute gold standard. The proposed algorithm evaluates the different experts and also gives an estimate of the actual hidden labels. Experimental results indicate that the proposed method is superior to the commonly used majority voting baseline