Purpose: Symptoms, macroscopic appearances and microscopic findings of Rathke's cleft cysts with magnetic resonance (MR) imaging.
Patients and Methods: We analyzed the data from 31 patients with pathologically confirmed Rathke's cleft cysts. MR appearances were evaluated on T₁WI, T₂WI and contrast T₁WI. Symptoms, macroscopic appearances and pathological findings were obtained from available medical records. We analyzed the images according to the following criteria:
1. findings on the location and shape of the lesions and form of the lesional wall;
2. the relationship between the maximum diameter of the lesions and symptoms;
3. the relationship between MR and macroscopic appearance;
4. the sites of adjacent contrast enhancement.
Results: The lesions were located mostly in both the intrasellar and suprasellar regions for a total of 87%. All lesions revealed either an oval or dumbbell shape with a smooth lesional wall. When correlated with physical symptoms, asymptomatic cases were associated with smaller lesions, while visual disturbances and dizziness were associated with relatively larger lesions. MR lesion signal intensity was related to the content of macroscopic appearance to some degree: the selected lesions showed shortening of T₁ and T₂ relaxation times in relation to the increase in protein concentration. This should have been macroscopically reflected in the color and turbidity of the liquid within the cyst. Adjacent contrast enhancement around the lesion was found at various sites, but anterior enhancement was most frequent. Circumferential enhancement was revealed to be derived from inflammatory changes.
Conclusion: Rathke's cleft cyst exhibits a varied MR signal. It may be difficult to differentiate from craniopharyngioma from the intensity alone.

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Purpose: The purpose of this study was to assess the usefulness of three-station black-blood fast short-inversion time inversion recovery (STIR) imaging in detecting and staging malignant lymphoma.
Methods: Seventeen patients with malignant lymphoma were examined with a 1.5T imager. The findings and stagings determined with three-station black-blood fast STIR imaging were compared with reference standards (e.g., computed tomography [CT] findings and clinical stagings).
Results: Three-station black-blood fast STIR imaging provided a fat-suppressed T₂-weighted imaging contrast with fewer flow artifacts and revealed nodal involvement as well as bone marrow and spleen involvement to an extent comparable with CT. Especially notable was the excellent specificity (94%) of this imaging technique. Regarding disease staging, significant agreement was observed between clinical staging (k=0.60) and staging as evaluated by three-station black-blood fast STIR, although the detection of lymphadenopathy in the thorax was relatively poor. The average time required for this imaging was approximately 30 min.
Conclusion: Three-station black-blood fast STIR MR imaging may be useful as a staging tool for malignant lymphoma because this imaging technique reveals lymphoma lesions, which determine the staging, without radiation exposure or the use of contrast agents.

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The feasibility of using a metabolite signal as an internal reference for self-referenced temperature distribution measurement was examined. Line scan echo-planar spectroscopic imaging (LSEPSI) was applied to obtain quick multi-voxel spectroscopic measurements and to avoid possible spectral degradation from motion. Temperature distribution in a rabbit brain in vivo was successfully visualized by means of the chemical shift of water, which was measured by using naturally abundant (up to 10 mM) N-acetyl-aspartate (NAA) as the reference signal. Unlike the phase-mapping approach, this technique does not require a pixel-by-pixel subtraction. Therefore, in theory, it is more resistant to inter-scan motion or changes in susceptibility. The spatial and temporal resolutions of this technique are 1.5 cm³ and 4.5 min. A higher signal-to-noise ratio and optimization of the water and outer-volume suppression capabilities will be required to further enhance the temperature-mapping capabilities.

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Dynamic contrast enhanced magnetic resonance imaging (dynamic MRI) represents a MRI version of non-diffusible tracer methods, the main clinical use of which is the physiological construction of what is conventionally referred to as perfusion images. The raw data utilized for constructing MRI perfusion images are time series of pixel signal alterations associated with the passage of a gadolinium containing contrast agent. Such time series are highly compatible with independent component analysis (ICA), a novel statistical signal processing technique capable of effectively separating a single mixture of multiple signals into their original independent source signals (blind separation). Accordingly, we applied ICA to dynamic MRI time series. The technique was found to be powerful, allowing for hitherto unobtainable assessment of regional cerebral hemodynamics in vivo.

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Purpose: To assess the feasibility of a curvature-based enhanced display system for detecting cerebral aneurysms in MR angiography.
Methods: MR angiography studies of 18 patients (eight male and 10 female, average age 65.7, age range 50 to 75 years old) with 23 known aneurysms were evaluated with a curvature-based display system. The two curvature features—the volumetric shape index and curvedness values—were calculated at each voxel. These were displayed independently on a workstation, overlaid on volume-rendered images. Two neuroradiologists evaluated the images for visibility and diagnosis of the cerebral aneurysms. The diagnostic results were compared with the original reports.
Results: The calculation time for each curvature index was 30 to 40 s for 120 to 140 slices of original MR angiography data. Shape index images emphasized smooth and round aneurysms more than aneurysms with irregular surfaces. Curvedness images revealed aneurysms well when the aneurysms had diameters that differed from those of the surrounding vessels. The computer-assisted-detection method detected 24 aneurysms, three of which were not pointed out in the initial report.
Conclusion: Our results show that the curvature-based display system we have developed is feasible and that it may help to detect small aneurysms that are prone to be overlooked in routine readings.

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Clinical experience with 3-tesla MRI for body applications has only a short history; to date, it has no proven practical advantage over 1.5-tesla or less powerful systems. However, the theoretical advantage of higher field strength—which includes a higher signal-to-noise ratio with identical scan parameters, higher special resolution available within clinically acceptable scan time, and better spectral resolution—can contribute to the clinical outcome. This paper seeks to demonstrate some of the clinical advantages of the 3-tesla system through preliminary experiences as well as the potential advantages of a 3-tesla system when combined with much of the hardware and software that is clinically accepted in the 1.5-tesla world.

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The quantification of intrahepatic lipids (IHLs) has attracted a great deal of interest pertaining to diagnostic treatment of type 2 diabetes mellitus. We report on an innovative approach to visualizing IHLs quantitatively by creating the best mix of the advantages of proton magnetic resonance spectroscopy (MRS) and the gradient echo (GRE) sequence on a 1.5T MR system. Proton MRS is considered to have the best precision and reliability; however, measuring a single voxel is time-consuming. On the other hand, the GRE sequence can provide information on IHLs, at least not quantitative, in a very short time.
IHL images can be created from the correlation between the relative content of IHLs obtained with proton MRS and the signal intensity of GRE images with a very high correlation coefficient (R=0.992). Our approach holds great potential for quantifying fat accumulation in every possible tissue quickly and precisely.

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The present study was designed to evaluate the use of a 1.0T portable permanent magnet MR system in obtaining microscopic MR images of the hyaline cartilage in vitro. A clear laminar appearance was demonstrated with this system. In addition, it was possible to demonstrate cartilage surface irregularity, a decrease in cartilage thickness, and T₂ alteration by proteoglycan depletion following up to 12 hours of trypsin treatment. In summary, the portable MR system is useful for investigating cartilage in vitro.

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A case of a 51-year-old male with previously unsuspected genetic hemochromatosis (GH) associated with hepatocellular carcinoma (HCC), for which MR imaging was useful in diagnosis, is presented. Contrast-enhanced ultrasonography depicted a mass in segment 8 of the liver and a liver tumor was suspected. The mass could not be revealed on unenhanced or enhanced CT examination. MR imaging with unenhanced T₁-weighted FLASH and T₂-weighted gradient echo sequences clearly depicted the tumor; the tumor appeared hyperintense against a background of low hepatic signal intensity caused by iron overload. The iron-overloaded liver provided a natural source of paramagnetic contrast for detection of HCC. Studies are required to further assess the accuracy of these sequences in detection of HCC in patients with GH.

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