Search

To evaluate the use of the double-echo steady-state (DESS) sequence for acquiring high-resolution breast images with diffusion and T2 weighting.Phantom scans were used to verify the T2 and diffusion weighting of the DESS sequence. Image distortion was evaluated in volunteers by comparing DESS images and conventional diffusion-weighted images (DWI) to spoiled gradient-echo images. The DESS sequence was added to a standard clinical protocol, and the resulting patient images were used to evaluate overall image quality and image contrast in lesions.The diffusion weighting of the DESS sequence can be easily modulated by changing the spoiler gradient area and flip angle. Radiologists rated DESS images as having higher resolution and less distortion than conventional DWI. Lesion-to-tissue contrast ratios are strongly correlated between DWI and DESS images (R=0.83) and between T2-weighted fast spin-echo and DESS images (R=0.80).The DESS sequence is able to acquire high-resolution 3D diffusion- and T2-weighted images in short scan times, with image quality that facilitates morphological assessment of lesions.

To describe the appearance of isolated intraductal papilloma on contrast-enhanced water-specific, high spatial-resolution and rapid dynamic breast MRI, a retrospective review of unilateral breast images of 15 pathologically proven papilloma was performed. MRI revealed three patterns: Four papillomas were small, smooth, enhancing masses at the posterior end of an enlarged duct, corresponding to the "small lumenal mass" appearance of papilloma known from galactography. MRI detected two of these "small lumenal mass" papillomas in patients with abnormal nipple discharge even when galactography was unsuccessful. Seven papillomas were irregular enhancing masses detected in patients without nipple discharge. None of these papillomas had specifically benign findings. All seven demonstrated rapid enhancement and three showed rim enhancement or spiculation. These "tumor-like" papillomas mimicked invasive breast cancer on MRI. Four papillomas were occult on MRI, not revealed by either contrast-enhanced MRI or fat-suppressed T(2)-weighted MRI. Intraductal papillomas present with a variable appearance on MRI ranging from occult to "small lumenal mass" papillomas to irregular rapidly enhancing lesions that cannot be distinguished from invasive cancers.

To compare the image quality of three techniques and diagnostic performance in detecting implant rupture.The study included 161 implants for the evaluation of image quality, composed of water-saturated short TI inversion recovery (herein called "water-sat STIR"), three-point Dixon techniques (herein called "Dixon"), and short TI inversion recovery fast spin-echo with iterative decomposition of silicone and water using least-squares approximation (herein called "STIR IDEAL") and included 41 implants for the evaluation of diagnostic performance in detecting rupture, composed of water-sat STIR and STIR IDEAL. Six image quality categories were evaluated and three classifications were used: normal implant, possible rupture, and definite rupture.Statistically significant differences were noted for the image quality categories (p0.001). STIR IDEAL was superior or equal to water-sat STIR in all image quality categories except artifact effects and superior to Dixon in all categories. Water-sat STIR performed the poorest for water suppression uniformity. The sensitivity and specificity in detecting implant rupture of STIR-IDEAL were 81.8 % and 77.8 % and the difference between two techniques was not statistically significant.STIR-IDEAL is a useful silicone-specific imaging technique demonstrating more robust water suppression and equivalent diagnostic accuracy for detecting implant rupture, than water-sat STIR, at the cost of longer scan time and an increase in minor motion artifacts.

Objective This study investigates the use of contrast-enhanced, T1-weighted, water-selective spectral–spatial 3D gradient echo magnetic resonance imaging (MRI) with magnetization transfer (3DSSMT) for detecting breast cancer in patients with intraparenchymal silicone. Conclusion Water-selective 3DSSMT provides superior fat and silicone suppression in patients with free silicone as compared with conventional fat saturation. It enables direct, high-quality, high-spatial-resolution, T1-weighted breast MRI of contrast enhancement without the need for subtraction processing and aids diagnosis of cancer in the breast with free silicone.

Susceptibility artifacts from magnetic resonance (MR)-compatible cryoprobes can distort MR images of iceballs. In this work, we investigate the ability of view angle tilting (VAT) to correct susceptibility induced distortions in MR images of cryosurgery. The efficacy of VAT was tested in an ex vivo bovine liver model of cryosurgery using MR-compatible cryoprobes. Artifacts on high bandwidth fast spin echo images of freezing obtained with and without VAT were compared with photographs of the actual iceball shape and size. In vivo imaging with VAT was demonstrated during percutaneous MR-guided cryosurgery of pig liver and brain. VAT was most successful in reducing probe and iceball distortions when the imaging plane was normal to the cryoprobe, and the cryoprobe was perpendicular to the main magnetic field of the scanner. VAT had the greatest benefit when used to correct MR images of freezing when the surface of the iceball was relatively near to the cryoprobe. For large iceballs, the artifact was small so the VAT correction was less important. We conclude that VAT significantly reduced distortions in the shape of the signal void corresponding to the extent of freezing visualized during MR-guided cryosurgery. This improved ability to visualize the exact location of the cryoprobe, as well as the precise shape of the iceball, particularly during initial freezing when the iceball is small, has potential to significantly improve the accuracy of MR-guided cryosurgery of small lesions, and the accuracy of MR-assisted temperature calculations that are based on precise imaging of the probe location, and boundary geometry of the iceball.