Usefulness of Contrast-Enhanced 3D-FLAIR MR Imaging for Differentiating Rathke Cleft Cyst from Cystic Craniopharyngioma.

BACKGROUND AND PURPOSE: Because it can be difficult to discriminate between a Rathke cleft cyst and cystic craniopharyngioma by conventional MR imaging alone, we investigated whether contrast-enhanced 3D T2-FLAIR MR imaging at 3T helps to distinguish a Rathke cleft cyst from a cystic craniopharyngioma. MATERIALS AND METHODS: We evaluated pre- and postcontrast T1-weighted and 3D T2-FLAIR images of 17 patients with pathologically confirmed Rathke cleft cyst (n = 10) or cystic craniopharyngioma (n = 7). All underwent 3T MR imaging studies before surgery. Two neuroradiologists independently recorded the enhancement grade of the lesion wall as grade 2 (most of the wall enhanced), grade 1 (some of the wall enhanced), and grade 0 (none of the wall enhanced). One neuroradiologist performed a blinded reading study of conventional MR images with/without 3D T2-FLAIR images. Interobserver agreement was determined by calculating the κ coefficient. Statistical analyses, including receiver operating characteristic curve analysis were performed. RESULTS: Interobserver agreement for postcontrast T1WI and 3D T2-FLAIR images was excellent (κ = 0.824 and κ = 0.867, respectively). Although the difference in the mean enhancement grade of Rathke cleft cysts and cystic craniopharyngiomas was not significant on postcontrast T1WIs, it was significant on postcontrast 3D T2-FLAIR images (P = .0011). The area under the receiver operating characteristic curve of the conventional MR alone and conventional MR with 3D T2-FLAIR readings was 0.879 and 1.0, respectively, though there was no significant difference in the area under the curve between the 2 readings. CONCLUSIONS: Contrast-enhanced 3D T2-FLAIR imaging at 3T helps to distinguish a Rathke cleft cyst from cystic craniopharyngioma.

Characterization of Carotid Plaque Components by Quantitative Susceptibility Mapping.

BACKGROUND AND PURPOSE: Intraplaque hemorrhage in the carotid artery is related to an increased risk of cerebrovascular ischemic events. We aimed to investigate whether quantitative susceptibility mapping can characterize carotid artery plaque components and quantify the severity of intraplaque hemorrhage. MATERIALS AND METHODS: For this ex vivo quantitative susceptibility mapping study, 9 carotid endarterectomy specimens were imaged on a 3T MR imaging scanner using a 3D multi-echo gradient-echo sequence and a microscopy coil. The samples were examined histologically using immunostains, including glycophorin A and Prussian blue. The areas of erythrocytes, iron deposits, calcification, and fibrous matrices observed on stained sections were compared with quantitative susceptibility mapping findings and their mean susceptibility values. RESULTS: Intraplaque hemorrhage and iron deposits were observed only in areas hyperintense on quantitative susceptibility mapping; calcifications and fibrous matrices were prevalent in hypointense areas. The mean susceptibility values for necrotic cores with intraplaque hemorrhage but no iron deposits, cores with iron deposits but no intraplaque hemorrhage, cores without either intraplaque hemorrhage or iron deposits, and cores with calcification were 188 ± 51, 129 ± 49, -11 ± 17, and -158 ± 78 parts per billion, respectively. There was a significant difference in the mean susceptibility values among the 4 histologic components (P < .01). The mean susceptibility values of the whole plaque positively correlated with the percentage area positive for glycophorin A (r = 0.65, P < .001) and Prussian blue (r = 0.47, P < .001). CONCLUSIONS: Our findings suggest that quantitative susceptibility mapping can characterize the composition of carotid plaques and quantify the degree of intraplaque hemorrhage and iron deposits.

Three-dimensional reversed fast imaging with steady-state precession diffusion-weighted imaging for the detection of middle ear cholesteatoma.

AIM: To determine the usefulness of three-dimensional reversed fast imaging with steady-state precession diffusion-weighted imaging (3D-PSIF DWI) for the detection of middle ear cholesteatoma. MATERIALS AND METHODS: The study population consisted of 81 patients who underwent 3D-PSIF-DWI at 3 T. They included cholesteatoma in 73 cases, otitis media in five, and cholesterol granuloma in three. Two observers independently performed qualitative evaluations for the detection of cholesteatoma and measured apparent diffusion coefficient (ADC) values and ADC ratios of the lesions. Kappa (κ) statistics, the intraclass correlation coefficient (ICC), the independent t-test, and receiver operating characteristic (ROC) analysis were used for statistical analysis. Pair-wise comparison of the ROC curves was performed using the area under the ROC curve (AUC). RESULTS: Interobserver agreement and ICC for the qualitative and quantitative evaluations were excellent (κ=0.92 and ICC=0.90-0.92, respectively). The ADC value and the ADC ratio were significantly lower for cholesteatoma than non-cholesteatoma lesions (p<0.0001). In <5 mm cholesteatoma group, the diagnostic performance of the ADC value (AUC=0.97) and the ADC ratio (AUC=1) was significantly superior to qualitative 3D-PSIF-DWI (AUC=0.76; p=0.0001 and <0.0001, respectively). For ≥5 mm cholesteatoma group, there were no significant differences in diagnostic performance among the three parameters. CONCLUSION: 3D-PSIF-DWI sequence is useful for the detection of middle ear cholesteatomas, especially <5 mm lesions.