[en] This paper evaluates the clinical benefit of reformatting high-resolution three-dimensional (3D) gradient Fourier transform-refocused images in assessing diskogenic disease of the cervical spine. Twenty patients were evaluated with MR imaging at 80 separate disk levels in the cervical spine. A 3DFT gradient recalled acquisition in a steady-state sequence was performed at 1.5-T with contiguous axial 1.5-mm sections. Proof of diagnosis was established in all patients with thin-section, high-resolution axial CT after intrathecal contrast medium administration. All axial scans were read randomly and independently by at least two neuroradiologists who were blinded to the clinical symptoms. In all cases, the axial images were interpreted again in combination with reformatted sagittal and oblique parasagittal images through the spinal canal and foramina

[en] This paper reports on thin-section spin-echo black-blood MR angiograms. A two-dimensional Fourier transform (2DFT) fast SE (FSE) sequence running on a 1.5-T clinical imager (4.0 Signa. GEMS, Waudesha) was modified to perform 3DFT multislab FSE imaging. In particular, section encoding was performed along the echo train. The Traced Ray by Array Processor (TRAP) program was modified to support inversion of image intensities, before lateral projection. Normal circle of Willis and common carotid SE 3D FSE volumes were acquired with 0.7-mm section thickness and SE T1 contrast characteristics and post processed by the TRAP program. Thin-section black-blood MR angiograms with T1 spin-echo contrast were obtained. Artifacts from complex flow in the carotid bulb were noted, fitting previous descriptions by Edelman of findings obtained with 2DFT black-blood techniques

[en] Conventional spin-echo MR images are still limited by section thickness, long imaging times, and artifacts emanating from cerebrospinal fluid flow. It has been shown that images can be rapidly acquired with very short repetition times (TRs) (i.e., in the stead state), which have significant contrast from true T2 differences. The purpose of this study was to evaluate the potential clinical utility of thin-section, high-resolution three-dimensional Fourier transform (3DFT) MR imaging with steady-state techniques (SSFP) in the brain. Twenty patients with intracerebral pathology were evaluated with long TR spin-echo and 3DFT SSFP sequences at 1.5 T. SSFP images used contiguous 2-mm sections, a TR of 24 msec, an echo time (TE) of 38 msec, and a theta of 10 degrees. The authors' conclude that contiguous thin-section, high-resolution 3DFT MR images with SSFP techniques can be obtained in relatively short times and provide intraparenchymal contrast similar to that seen on long TR, long TE-spin-echo images

[en] This paper investigates a gradient-echo sequence using frequency-selective fat suppression in a three-dimensional Fourier transform (3DFT) mode to assess the benefits of this technique in orbital pathology. The authors used a frequency-selective preexcitation of the fat resonance in combination with a 3DFT RF-spoiled gradient-echo sequence (40/5/30 degrees) and with intravenous (IV) Gd-DTPA injection (0.1 mmol/kg) in 10 patients who had documented retrobulbar lesions. All patients were evaluated with both short TR/TE spin-echo and fat-suppressed pre- and postcontrast MR imaging at 1.5 T

[en] The appearance of intracranial sarcoidosis on Gd-DTPA-enhanced MR imaging has not been previously reported. The authors have studied five patients with T1-and T2-weighted pre-GD and T1-weighted post-GD sequences. Images showed diffuse meningeal involvement suspected on the unenhanced scans in only one patient, enhancing extraaxial masses mimicking meningiomas, and enhancing and nonenhancing intraaxial lesions. In four of five patients, the diagnosis of intracranial sarcoidosis was suggested only after Gd-DTPA administration. The addition of Gd-DTPA greatly enhanced the sensitivity of MR imaging to the extraaxial and meningeal manifestations of central nervous system sarcoidosis

[en] Internuclear ophthalmoplegia is a gaze disorder characterized by impaired adduction of the side of a lesion in the medial longitudinal fasciculus (MLF) with dissociated nystagmus of the abducting eye. Eleven patients with internuclear ophthalmoplegia (nine with multiple sclerosis, two with infarction) were examined with spin-echo MR imaging performed at 1.5 T. Nine of the 11 patients also underwent CT. MR imaging was highly sensitive (10 of 11 cases) and CT was of no value (0 of 9 cases) in detecting clinically suspected MLF lesions. These lesions must be distinguished from ''pseudo-MLF hyperintensity,'' which appears as a thin, strictly midline, linear hyperintensity just interior to the fourth ventricle and aqueduct in healthy subjects. True MLF lesions are nodular, more prominent, and slightly off the midline, corresponding to the paramedian anatomic site of the MLF

[en] Spin-echo MR imaging with intravenous enhancement has been very useful in evaluating the postoperative lumbar spine. Limitations, however, include difficulties in identifying subtle enhancement of scar and in distinguishing enhancement from epidural fat, which necessitates precontrast imaging. In this study, the authors have used a variant of the Chopper technique, based on frequency-selective excitation followed by in-phase and out-of-phase acquisitions. This sequence was used with intravenous Gd-DTPA in 10 patients who had undergone surgery for lumbar discogenic disease. MR imaging was performed at 1.5 T with both short repetition time, short echo time spin echo and Chopper before and after contrast material. In all cases, the regions of enhancement with intravenous contrast material were significantly more conspicuous, on Chopper sequences that on conventional spin-echo images. From their data, the authors believe that this type of chemical shift imaging, in combination with the use of intravenous contrast material, is useful in the evaluation of the postoperative lumbar spine

[en] Nine patients with orbital lesions were examined with surface coil MR imaging using both conventional spin-echo sequences and the Dixon spectroscopic technique. This technique results in cancellation of signal in voxels containing equal amounts of fat and water protons (i.e., at fat-water interfaces). Proton spectroscopic phase-dependent contrast images had three advantages over conventional images in the series: (1) orbital masses and their extent were more clearly delineated, due to edge enhancement at fat-water interfaces, (2) misregistration artifacts which result from chemical shift on conventional images were eliminated, and (3) intratumoral high-intensity signal from blood could be differentiated from that of fat. In this preliminary study, proton spectroscopic phase-dependent contrast imaging of the orbit appeared to add useful information to that obtained with conventional spin-echo imaging techniques and without prolonging imaging time significantly

[en] The location of Gd-DTPA-enhancing multiple sclerosis (MS) plaques on MR imaging has been found to correspond to the site of new neurologic deficits; however, characteristics differentiating new from old plaques on nonenhanced T2-weighted images have not been described. In the present study, nonenhanced MS characteristics (mean pixel intensity, size and contour) of plaques that enhanced with gadolinium were compared to characteristics of plaques that did not enhance. The gadolinium-enhancing plaques, in general, had a lower mean pixel value and were less well defined on T2-weighted images than nonenhancing lesions. Their intensity, however, increased relative to adjacent plaques on more heavily weighted T2-images

[en] Conventional MR imaging with surface coils has significantly improved the anatomic depiction of ocular structures. In this study, the authors use a very small field of view (FOV) to demonstrate the anterior structures of the globe with ultrahigh resolution. Aliasing in their reduced FOV imaging is eliminated by using a ''strip image'' technique, which intersects a selectively excited section with an orthogonal selective 180⁰ radio frequency pulse flanked by crusher gradient pulses. In all cases, spin-echo imaging is performed with the use of 3-mm-thick sections with repetition time of 600 msec, echo time to 20 msec, two to four excitations, 256 X 128 or 256 X 256 matrix, and FOV of 4 cm. Anterior intraocular structures (ie, cornea, lens, and ciliary apparatus) are clearly depicted without interference from aliasing. The authors believe that this method of ultrahigh-resolution MR imaging may become useful in demonstrating normal anatomy and pathologic conditions involving these intraocular structures