Purpose:To develop and apply a semiautomatic method of segmenting fibroglandular tissue to quantify magnetic resonance (MR) imaging contrast material-enhancement kinetics of breast background parenchyma (BP) and lesions throughout the phases of the menstrual cycle in women with benign and malignant lesions. Materials and Methods:The institutional review board approved this retrospective HIPAA-compliant study, and informed consent was waived. From December 2008 to August 2011, 58 premenopausal women who had undergone contrast materialenhanced MR imaging and MR imaging-guided biopsy were identified. The longest time from the start of the last known period was 34 days. One lesion per patient (37 benign and 21 malignant) was analyzed. The patient groups were stratified according to the week of the menstrual cycle when MR imaging was performed. A method based on principal component analysis (PCA) was applied for quantitative analysis of signal enhancement in the BP and lesions by using the percentage of slope and percentage of enhancement. Linear regression and the Mann-Whitney U test were used to assess the association between the kinetic parameters and the week of the menstrual cycle. Results:In the women with benign lesions, percentages of slope and enhancement for both BP and lesions during week 2 were significantly (P , .05) lower than those in week 4. Percentage of enhancement in the lesion in week 2 was lower than that in week 3 (P , .05). The MR images of women with malignant lesions showed no significant difference between the weeks for any of the parameters. There was a strong positive correlation between lesion and BP percentage of slope (r = 0.72) and between lesion and BP percentage of enhancement (r = 0.67) in the benign group. There was also a significant (P = .03) difference in lesion percentage of slope between the benign and malignant groups at week 2. Conclusion:The PCA-based method can quantify contrast enhancement kinetics of BP semiautomatically, and kinetics of BP and lesions vary according to the week of the menstrual cycle in benign but not in malignant lesions.q RSNA, 2013
Purpose To investigate the feasibility of using simultaneous breast MRI and PET to assess the synergy of MR pharmacokinetic and fluorine-18 fluorodeoxyglucose (18F-FDG) uptake data to characterize tumor aggressiveness in terms of metastatic burden and Ki67 status. Methods Twelve consecutive patients underwent breast and whole body PET/MRI. During the MR scan, PET events were simultaneously accumulated. MR contrast kinetic model parametric maps were computed using the extended Tofts model, including the volume transfer constant between blood plasma and the interstitial space (Ktrans), the transfer constant from the interstitial space to the blood plasma (kep), and the plasmatic volume fraction (Vp). Results Patients with systemic metastases had a significantly lower kep compared to those with local disease (0.45 vs 0.99 min−1, p=0.011). Metastatic burden correlated positively with Ktrans and standardized uptake value (SUV), and negatively with kep. Ki67 positive tumors had a significantly greater Ktrans compared to Ki67 negative tumors (0.29 vs 0.45 min−1, p=0.03). A negative correlation was found between metabolic tumor volume and transfer constant (Ktrans or Kep). Conclusion These preliminary results suggest that MR pharmacokinetic parameters and FDG-PET may aid in the assessment of tumor aggressiveness and metastatic potential. Future studies are warranted with a larger cohort to further assess the role of pharmacokinetic modeling in simultaneous PET/MRI imaging.
Early diagnosis and management of neck infections and inflammatory processes is a common challenge for emergency and ear, neck and throat physicians, as well as radiologists. Emergency neck infections are diverse in their presentation, ranging from a transient enlargement of a lymph node to a rapidly spreading necrotizing fasciitis. Symptoms and signs, with the clinical history, usually suggest the diagnosis. But complex neck anatomy and sometimes limited physical examination can obscure and delay diagnosis, thus the need for an appropriate imaging exam and correct interpretation. In this pictorial review, we will consider common neck acute inflammatory processes that may be encountered in the emergency room and discuss some of their salient imaging findings.
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