Browsing by Subject "Contrast Media"

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Open Access
Gadolinium leakage into subarachnoid space and cystic metastases
(2013) Elçin Yildiz, A.; Atli, E.; Karli Oǧuz, K.
Subarachnoid space (SAS) and cystic metastatic lesions of brain parenchyma appear hypointense on fluid-attenuated inversion-recovery (FLAIR) and T1-weighted magnetic resonance imaging (MRI) unless there is a hemorrhage or elevated protein content. Otherwise, delayed enhancement and accumulation of contrast media in SAS or cyst of metastases should be considered. We present hyperintense SAS and cystic brain metastases of lung cancer on FLAIR and T1-weighted MRI, respectively, in a patient who had been previously given contrast media for imaging of spinal metastases and had mildly impaired renal functions, and discuss the relevant literature. © Turkish Society of Radiology 2013.
Open Access
Malignant-lesion segmentation using 4D co-occurrence texture analysis applied to dynamic contrast-enhanced magnetic resonance breast image data
(2007) Woods, B.J.; Clymer, B.D.; Kurc, T.; Heverhagen J.T.; Stevens, R.; Orsdemir, A.; Bulan O.; Knopp, M.V.
Purpose: To investigate the use of four-dimensional (4D) co-occurrence-based texture analysis to distinguish between nonmalignant and malignant tissues in dynamic contrast-enhanced (DCE) MR images. Materials and Methods: 4D texture analysis was performedon DCE-MRI data sets of breast lesions. A model-free neural network-based classification system assigned each voxel a "nonmalignant" or "malignant" label based on the textural features. The classification results were compared via receiver operating characteristic (ROC) curve analysis with the manual lesion segmentation produced by two radiologists (observers 1 and 2). Results: The mean sensitivity and specificity of the classifier agreed with the mean observer 2 performance when compared with segmentations by observer 1 for a 95% confidence interval, using a two-sided t-test with α = 0.05. The results show that an area under the ROC curve (Az) of 0.99948, 0.99867, and 0.99957 can be achieved by comparing the classifier vs. observer 1, classifier vs. union of both observers, and classifier vs. intersection of both observers, respectively. Conclusion: This study shows that a neural network classifier based on 4D texture analysis inputs can achieve a performance comparable to that achieved by human observers, and that further research in this area is warranted. © 2007 Wiley-Liss, Inc.
Open Access
System for MR image-guided prostate interventions: Canine study
(Radiological Society of North America, Inc., 2003) Susil, R. C.; Krieger, A.; Derbyshire, J. A.; Tanacs, A.; Whitcomb, L. L.; Fichtinger, G.; Atalar, Ergin
The purpose of this study was to demonstrate the use of a transrectal system that enables precise magnetic resonance (MR) image guidance and monitoring of prostate interventions. The system used a closed-bore 1.5-T MR imaging unit and enables one to take advantage of the higher signal-to-noise ratio achieved with traditional magnet designs, which is crucial for accurate targeting and monitoring of prostate interventions. In the first of the four canine studies, reliable needle placement, with all needles placed within 2 mm of the desired target site, was achieved. In two other studies, MR imaging was used to monitor distribution of injected contrast agent solution (gadopentetate dimeglumine mixed with trypan blue dye) in and around the prostate, thereby confirming that solution had been delivered to the desired tissue and also detecting faulty injections. In the final study, accurate placement and MR imaging of brachytherapy seeds in the prostate were demonstrated. The described system provides a flexible platform for a variety of minimally invasive MR image-guided therapeutic and diagnostic prostate interventions. © RSNA, 2003.