Precontrast and postcontrast susceptibility-weighted imaging in the assessment of intracranial brain neoplasms at 1.5 T.

PURPOSE: The goal of this study was to estimate pre- and post-gadolinium-enhanced high-spatial resolution susceptibility-weighted imaging (SWI) in patients with brain neoplasms. MATERIALS AND METHODS: A total of 17 patients (8 women, 9 men) with brain neoplasms participated in this study. In addition to conventional magnetic resonance imaging, pre- and post-gadolinium-enhanced SWI was performed. The contrast-to-noise ratio (CNR) and major diameters of the brain tumor were measured for quantitative analyses, and intratumoral susceptibility signal intensity (ITSS) was graded for semiquantitative analysis. RESULTS: Both bright and dark enhancement were observed at the pathological lesion on postcontrast SWI. Some postcontrast SWI results suggested leakage of contrast material due to breakdown of the blood-brain barrier. There were no statistical differences (Student's t-test) between postcontrast SWI and three-dimensional (3D) T1-weighted images regarding the major diameters of the brain tumors. CNR of postcontrast 3D T1-weighted images was statistically superior to that of postcontrast SW images (P < 0.01, Wilcoxon signed-rank test). Malignant tumors tended to have a higher ITSS score. CONCLUSION: SWI clearly visualized the architecture of brain neoplasms. This imaging technique may be useful for evaluating tumor characterization in clinical use.

Assessment of arteriovenous malformations with 3-Tesla time-resolved, contrast-enhanced, three-dimensional magnetic resonance angiography.

OBJECT: Although conventional catheter angiography is commonly used in the evaluation of intracranial arteriovenous malformations (AVMs), less invasive tools are more suitable for screening or follow-up. Older MR angiography techniques cannot provide high enough temporal and spatial resolution for assessing AVMs. Threetesla time-resolved imaging of contrast kinetics (TRICKS)-a time-resolved, contrast-enhanced 3D MR angiography technique-achieves subsecond time resolution without sacrificing spatial resolution. The purpose of this study was to assess the accuracy of TRICKS at 3 T in the evaluation of AVMs. METHODS: Between November 2006 and November 2007, 31 patients who were known to have AVMs underwent evaluation in a 3-T unit with the TRICKS technique. The TRICKS images were then evaluated independently by 2 radiologists for nidus detection, early venous filling detection, and Spetzler-Martin classification, and these results were compared with the results of catheter angiography. RESULTS: Time-resolved imaging of contrast kinetics achieved 96% sensitivity and 100% specificity both in nidus detection and early venous filling detection. The Spetzler-Martin grades also showed excellent correlation with catheter angiography findings (kappa= 0.89). CONCLUSIONS: Although this is a preliminary study, the authors' results indicate that time-resolved contrast-enhanced 3D MR angiography at 3 T is a good tool to assess AVMs, and has the potential to replace catheter angiography in screening or follow-up examinations of patients with AVMs.

Two-dimensional magnetic resonance digital subtraction angiography using array spatial sensitivity encoding techniques in the assessment of intracranial hemodynamics.

OBJECTIVE: Array spatial sensitivity encoding techniques (ASSET) were employed to improve the temporal resolution of two-dimensional (2D) thick-slice contrast-enhanced magnetic resonance digital subtraction angiography (MRDSA). METHODS: 2D MRDSA using ASSET was performed in 28 patients via fast spoiled gradient-echo sequence (TR/TE 5.4/1.5 ms; FA 60; FOV 24x24 cm; matrix size 256x256; slicethickness 50-70 mm), followed by a bolus injection of gadolinium chelate and subsequent saline flush, for 40 seconds on a sagittal plane. Images were evaluated for visualization of normal intracranial vessels and brain lesions utilizing a three-point scale; additionally, in 10 of the 28 patients, results were compared with those of conventional 2D MRDSA. RESULTS: 2D MRDSA using ASSET, which improved temporal resolution from 1.45 to 0.77 seconds, displayed image quality comparable to that of conventional 2D MRDSA. Moreover, this technique afforded superior detectability with respect to early venous filling in patients with arteriovenous malformations (AVMs). CONCLUSION: ASSET improves the temporal resolution of 2D MRDSA without compromising spatial resolution.