Water-silicone separated volumetric MR acquisition for rapid assessment of breast implants

Purpose: To develop a robust T2-weighted volumetric imaging technique with uniform water-silicone separation and simultaneous fat suppression for rapid assessment of breast implants in a single acquisition. Materials and Methods: A three-dimensional (3D) fast spin echo sequence that uses variable refocusing flip angles was combined with a three-point chemical-shift technique (IDEAL) and short tau inversion recovery (STIR). Phase shifts of -π/6, +π/2, and +7π/6 between water and silicone were used for IDEAL processing. For comparison, two-dimensional images using 2D-FSE-IDEAL with STIR were also acquired in axial, coronal, and sagittal orientations. Results: Near-isotropic (true spatial resolution-0.9 ×1.3 × 2.0 mm 3) volumetric breast images with uniform water-silicone separation and simultaneous fat suppression were acquired successfully in clinically feasible scan times (7:00-10:00 min). The 2D images were acquired with the same in-plane resolution (0.9 × 1.3 mm 2), but the slice thickness was increased to 6 mm with a slice gap of 1 mm for complete coverage of the implants in a reasonable scan time, which varied between 18:00 and 22:30 min. Conclusion: The single volumetric acquisition with uniform water and silicone separation enables images to be reformatted into any orientation. This allows comprehensive assessment of breast implant integrity in less than 10 min of total examination time. © 2012 Wiley Periodicals, Inc

T2-weighted 3D fast spin echo imaging with water-fat separation in a single acquisition

Purpose: To develop a robust 3D fast spin echo (FSE) T2-weighted imaging method with uniform water and fat separation in a single acquisition, amenable to high-quality multiplanar reformations. Materials and Methods: The Iterative Decomposition of water and fat with Echo Asymmetry and Least squares estimation (IDEAL) method was integrated with modulated refocusing flip angle 3D-FSE. Echoes required for IDEAL processing were acquired by shifting the readout gradient with respect to the Carr-Purcell-Meiboom-Gill echo. To reduce the scan time, an alternative data acquisition using two gradient echoes per repetition was implemented. Using the latter approach, a total of four gradient echoes were acquired in two repetitions and used in the modified IDEAL reconstruction. Results: 3D-FSE T2-weighted images with uniform water-fat separation were successfully acquired in various anatomies including breast, abdomen, knee, and ankle in clinically feasible scan times, ranging from 5:30-8:30 minutes. Using water-only and fat-only images, in-phase and out-of-phase images were reconstructed. Conclusion: 3D-FSE-IDEAL provides volumetric T2-weighted images with uniform water and fat separation in a single acquisition. High-resolution images with multiple contrasts can be reformatted to any orientation from a single acquisition. This could potentially replace 2D-FSE acquisitions with and without fat suppression and in multiple planes, thus improving overall imaging efficiency. © 2010 Wiley-Liss, Inc

Venous Aneurysms: MR Diagnosis with the "Layered Gadolinium" sign

OBJECTIVE: Our goal was to present MR findings in venous aneurysms and introduce the "layered gadolinium" sign as an ancillary diagnostic finding. METHOD: Gadolinium-enhanced MR images of three patients with retroperitoneal venous aneurysms were retrospectively reviewed. Prior to MRI, venous aneurysm had been suspected clinically in only one patient. Surgical correlation was available in one patient. A phantom was constructed and imaged to investigate the cause of the layered gadolinium sign. RESULTS: A gradation of signal intensity, the layered gadolinium sign, was observed in three patients with venous aneurysms on postcontrast T1-weighted images. The anterior portion of the aneurysms demonstrated high signal intensity separated by a sharp interface from the low signal intensity posterior region. Unenhanced time-of-flight MR venography, color Doppler, and duplex sonography failed to demonstrate flow in the patient with surgical proof. CONCLUSION: The layered gadolinium sign may be helpful in the diagnosis of venous aneurysm and in differentiating these masses from solid neoplasms

Time-resolved Vessel-selective Digital Subtraction MR Angiography of the Cerebral Vasculature with Arterial Spin Labeling1

MR imaging and arterial spin labeling can be used to perform cerebral angiography with dynamic inflow and vessel-specific information that is similar to that obtained with conventional x-ray digital subtraction angiography