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MRI Alone (mri + alone)
Selected AbstractsMRI measurement of time-resolved wall shear stress vectors in a carotid bifurcation model, and comparison with CFD predictionsJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2003Panorea Papathanasopoulou MSc Abstract Purpose To study pulsatile fluid flow in a physiologically realistic model of the human carotid bifurcation, and to derive wall shear stress (WSS) vectors. Materials and Methods WSS vectors were calculated from time-resolved 3D phase-contrast (PC) MRI measurements of the velocity field. The technique was first validated with sinusoidal flow in a straight tube, and then used in a model of a healthy human carotid bifurcation. Velocity measurements in the inflow and outflow regions were also used as boundary conditions for computational fluid dynamics (CFD) calculations of WSS, which were compared with those derived from MRI alone. Results The straight tube measurements gave WSS results that were within 15% of the theoretical value. WSS results for the phantom showed the main features expected from fluid dynamics, notably the low values in the bulb region of the internal carotid artery, with a return to ordered flow further downstream. MRI was not able to detect the high WSS values along the divider wall that were predicted by the CFD model. Otherwise, there was good general agreement between MRI and CFD. Conclusion This is the first report of time-resolved WSS vectors estimated from 3D-MRI data. The technique worked well except in regions of disturbed flow, where the combination with CFD modeling is clearly advantageous. J. Magn. Reson. Imaging 2003;17:153,162. © 2003 Wiley-Liss, Inc. [source] MR-guided percutaneous core biopsy of small breast lesions: First experience with a vertically open 0.5T scannerJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2002Jens P. Schneider MD Abstract Purpose The growing use of highly sensitive but only moderate specific breast MRI requires the development of both minimal-invasive as well as precise biopsy systems. The aim of the study was to prove the accuracy and feasibility of a biopsy procedure carried out in prone position in a vertically opened MR imager. Materials and Methods The biopsies were carried out in 21 women with lesions visible on MRI alone using an open breast coil with an integrated biopsy device. A 14 G coaxial needle was placed under near real-time MRI-guidance. After the tip of this needle was verified in contact with the lesion, we used a non MR-compatible, but MR-safe biopsy gun with a 16 G canula to take four to eight cores. Results We found eight malignant and 12 benign lesions. In one patient the procedure was not successful. In case of malignancy, the operation confirmed the diagnosis in all cases. The 12/21 patients with benign lesions have been followed without evidence of lesions growth over eight to 28 months. Conclusion The described procedure allows MRI-guided minimal invasive core biopsy of small breast lesions (five to 17 mm) with a high degree of accuracy. J. Magn. Reson. Imaging 2002;15:374-385. © 2002 Wiley-Liss, Inc. [source] Development of a decision support system for diagnosis and grading of brain tumours using in vivo magnetic resonance single voxel spectraNMR IN BIOMEDICINE, Issue 4 2006Anne R. Tate Abstract A computer-based decision support system to assist radiologists in diagnosing and grading brain tumours has been developed by the multi-centre INTERPRET project. Spectra from a database of 1H single-voxel spectra of different types of brain tumours, acquired in vivo from 334 patients at four different centres, are clustered according to their pathology, using automated pattern recognition techniques and the results are presented as a two-dimensional scatterplot using an intuitive graphical user interface (GUI). Formal quality control procedures were performed to standardize the performance of the instruments and check each spectrum, and teams of expert neuroradiologists, neurosurgeons, neurologists and neuropathologists clinically validated each case. The prototype decision support system (DSS) successfully classified 89% of the cases in an independent test set of 91 cases of the most frequent tumour types (meningiomas, low-grade gliomas and high-grade malignant tumours,glioblastomas and metastases). It also helps to resolve diagnostic difficulty in borderline cases. When the prototype was tested by radiologists and other clinicians it was favourably received. Results of the preliminary clinical analysis of the added value of using the DSS for brain tumour diagnosis with MRS showed a small but significant improvement over MRI used alone. In the comparison of individual pathologies, PNETs were significantly better diagnosed with the DSS than with MRI alone. Copyright © 2006 John Wiley & Sons, Ltd. [source] Response measurement after intraarterial chemoradiation in advanced head and neck carcinomaCANCER, Issue 8 2006Magnetic resonance imaging, evaluation under general anesthesia? Abstract BACKGROUND The objectives of this prospective trial were to evaluate the diagnostic accuracy and predictive value of magnetic resonance imaging (MRI) and to use MRI evaluation under general anesthesia (EGA) 6 to 8 weeks after chemoradiation to determine local control. METHODS Eighty-two consecutive patients with advanced-stage squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, or supraglottic larynx were treated with selective targeted chemoradiation. All patients who completed treatment and survived had a minimum follow-up of 3 years. MRI and EGA were performed from 6 to 8 weeks after treatment. Posttreatment MRI findings were compared with pretreatment MRI findings and were graded for risk of local recurrence/residual disease on a 4-point scale. The diagnosis of treatment failure was based on tissue biopsies, which were obtained during EGA or later during follow-up. The predictive value of MRI was analyzed by using a Cox proportional hazards model. RESULTS Only 1 patient with MRI Grade 0 or 1 findings (discrete mass < 10 mm; n = 62 patients) had residual disease 6 to 8 weeks after treatment that was detected during EGA. In 5 patients with MRI findings of Grade 2a and 2b (mass > 10 mm; n = 20 patients), residual disease was detected. After 2 years, 23 patients had a local failure (28%). Twelve local failures were found among 62 patients who had MRI findings of Grade 0 and 1. Posttreatment MRI emerged as an independent predictive factor (hazard ratio, 3.0; P = .014) for local control. CONCLUSIONS Posttreatment MRI studies provided predictive information on local control in addition to pretreatment predictors. In patients with focal masses < 10 mm, the combination of response evaluation under general anesthesia and posttreatment MRI from 6 to 8 weeks after chemoradiation hardly provided more information on the local control than posttreatment MRI alone. Cancer 2006. © 2006 American Cancer Society. [source] Screening women at high risk for breast cancer with mammography and magnetic resonance imaging,CANCER, Issue 9 2005Constance D. Lehman M.D., Ph.D. Abstract BACKGROUND The authors compared the performance of screening mammography versus magnetic resonance imaging (MRI) in women at genetically high risk for breast cancer. METHODS The authors conducted an international prospective study of screening mammography and MRI in asymptomatic, genetically high-risk women age , 25 years. Women with a history of breast cancer were eligible for a contralateral screening if they had been diagnosed within 5 years or a bilateral screening if they had been diagnosed > 5 years previously. All examinations (MRI, mammography, and clinical breast examination [CBE]) were performed within 90 days of each other. RESULTS In total, 390 eligible women were enrolled by 13 sites, and 367 women completed all study examinations. Imaging evaluations recommended 38 biopsies, and 27 biopsies were performed, resulting in 4 cancers diagnosed for an overall 1.1% cancer yield (95% confidence interval [95%CI], 0.3,2.8%). MRI detected all four cancers, whereas mammography detected one cancer. The diagnostic yield of mammography was 0.3% (95%CI, 0.01,1.5%). The yield of cancer by MRI alone was 0.8% (95%CI, , 0.3,2.0%). The biopsy recommendation rates for MRI and mammography were 8.5% (95%CI, 5.8,11.8%) and 2.2% (95%CI, 0.1,4.3%). CONCLUSIONS Screening MRI in high-risk women was capable of detecting mammographically and clinically occult breast cancer. Screening MRI resulted in 22 of 367 of women (6%) who had negative mammogram and negative CBE examinations undergoing biopsy, resulting in 3 additional cancers detected. MRI also resulted in 19 (5%) false-positive outcomes, which resulted in benign biopsies. Cancer 2005. © 2005 American Cancer Society. [source] | ||||||||||