Dynamic breast MRI: does lower temporal resolution negatively affect clinical kinetic analysis?
ABSTRACT The purpose of this study was to compare the differences in kinetic assessments of lesions at breast MRI performed with higher and lower temporal resolution.
All consecutively evaluated BI-RADS category 4, 5, and 6 lesions imaged with breast MRI and pathologically confirmed from October 2005 to August 2009 were identified. Patients underwent MRI with one of two dynamic contrast-enhanced protocols: one with 90-second (October 2005-June 2006) and another with 180-second (July 2006-August 2009) temporal resolution. Studies were processed with a computer-aided evaluation system with initial and delayed contrast-enhanced time points with the k-space centered 90 and 450 seconds after contrast injection. Initial-phase peak enhancement, delayed-phase predominant curve type, and worst curve type were recorded and compared for benign and malignant lesions across protocols.
The analysis set comprised 993 lesions: 145 imaged with the 90-second acquisition (17 benign, 28 ductal carcinoma in situ [DCIS], 100 invasive cancer) and 848 imaged with the 180-second acquisition (212 benign, 145 DCIS, 491 invasive cancer). Peak enhancement was significantly higher for both benign lesions (p = 0.01) and invasive cancers (p = 0.0008) with the 180-second protocol. Peak enhancement of DCIS was similar in the two protocols (p = 0.88). Delayed-phase kinetics were similar for the two protocols for both benign and malignant lesions when defined by predominant or worst curve type.
Although it has lower temporal resolution, a 180-second acquisition may be preferable because it allows higher spatial resolution and captures higher initial-phase peak enhancement without loss of delayed-phase kinetic information.
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ABSTRACT: OBJECTIVE. The purpose of this study is to assess associations between patient characteristics and apparent diffusion coefficient (ADC) values of normal breast fibroglandular tissue on diffusion-weighted imaging (DWI) at 3 T. MATERIALS AND METHODS. The retrospective study included 103 women with negative bilateral findings on 3-T breast MRI examinations (BI-RADS category 1). DWI was acquired during clinical breast MRI scans using b = 0 and b = 800 s/mm(2). Mean ADC of normal breast fibroglandular tissue was calculated for each breast using a semiautomated software tool in which parenchyma pixels were selected by interactive thresholding of the b = 0 s/mm(2) image to exclude fat. Intrasubject right- and left-breast ADC values were compared and averaged together to evaluate the association of mean breast ADC with age, mammographic breast density, and background parenchymal enhancement. RESULTS. Overall mean ± SD breast ADC was 1.62 ± 0.30 × 10(-3) mm(2)/s. Intrasubject right- and left-breast ADC measurements were highly correlated (R(2) = 0.89; p < 0.0001). Increased breast density was strongly associated with increased ADC (p ≤ 0.0001). Age and background parenchymal enhancement were not associated with ADC. CONCLUSION. Normal breast parenchymal ADC values increase with mammographic density but are independent of age and background parenchymal enhancement. Because breast malignancies have been shown to have low ADC values, DWI may be particularly valuable in women with dense breasts owing to greater contrast between lesion and normal tissue.American Journal of Roentgenology 05/2014; 202(5):W496-502. DOI:10.2214/AJR.13.11159 · 2.74 Impact Factor
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ABSTRACT: Breast dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) scanning protocols vary widely. The purpose of this study was to determine the effects of postcontrast timing on delayed-phase lesion kinetics assessment and ability to discriminate malignant from benign lesions.Academic Radiology 07/2014; 21(9). DOI:10.1016/j.acra.2014.04.013 · 2.08 Impact Factor
Article: High-Quality Breast MRI[Show abstract] [Hide abstract]
ABSTRACT: Breast magnetic resonance imaging (MRI) demands the competing factors of high spatial resolution, good temporal resolution, high signal-to-noise ratios (SNR), and complete bilateral breast coverage. Achieving these four competing factors requires modern MRI equipment with high magnetic field strength, good magnetic field homogeneity, high maximum gradient strength with short rise times, dedicated multichannel bilateral breast coils with prone patient positioning, and 3D (volume) gradient-echo MRI pulse sequences with short TR, short TE, high spatial resolution, and reasonably short acquisition times. Only then can breast MRI provide high sensitivity to breast cancers revealed through gadolinium-based contrast agent enhancement, combined with high specificity based both on morphology and temporal enhancement characteristics. This chapter discusses the equipment and pulse sequences needed to achieve high-quality breast MRI.Radiologic Clinics of North America 05/2014; 52(3). DOI:10.1016/j.rcl.2013.12.002 · 1.83 Impact Factor