Article

Contrast-enhanced, high-resolution, susceptibility-weighted magnetic resonance imaging of the brain: dose-dependent optimization at 3 tesla and 1.5 tesla in healthy volunteers.

Department of Radiology, Osteology/Head and Neck imaging, MR Centre of Excellence, Medical Diagnostic Division, Medical University Vienna, Austria.
Investigative Radiology (Impact Factor: 5.46). 04/2006; 41(3):249-55. DOI: 10.1097/01.rli.0000188360.24222.5e
Source: PubMed

ABSTRACT We sought to determine the optimal dose of a contrast agent with known high relaxivity on 1.5 and 3 Tesla scanners that would achieve the best compromise between image quality and scan time for the clinical application of contrast-enhanced susceptibility-weighted imaging (CE-SWI).
Pre- and postcontrast SWI was performed with different contrast agent doses (0.05, 0.1, and 0.2 mmol/kg gadobenate dimeglumine) at both 1.5 and 3 T in 6 healthy volunteers, resulting in 72 examinations. Venograms were created from minimum intensity projection reconstructions over specified deep white matter volumes to enhance the visual appearance of connected venous structures. Three independent radiologists blindly rated the visibility of the veins on a continuous scale of 1 to 10. A general linear model was used for statistical evaluation, with fixed effects of the contrast agent dose, the field strength, the rater and the patients as a random effect.
With CE-SWI, we found significant differences in the visibility of the deep veins dependent on the contrast media dose (P=0.02). At 3 T, the visibility of deep venous vessels, with regard to susceptibility effect, image quality, and scan time reduction after a standard contrast agent dose 0.1 mmol/kg was significantly better than that achieved with 0.05 mmol/kg. The visibility was considered equal with 0.1 mmol/kg of the contrast agent to the precontrast images and a dose of 0.2 mmol/kg. At 1.5 T, no significant difference was found between the 4 contrast agent doses. We found no difference in the visibility of the veins with the shorter sequences at 3 T compared with the sequences at 1.5 T.
Only a standard dose (0.1 mmol/kg) of gadobenate dimeglumine is required to achieve the optimum susceptibility effect and image quality at 3 T, together with a reduced scan time. This result can be attributed to the higher relaxivity of gadobenate dimeglumine, compared with conventional gadolinium chelates.

0 Bookmarks
 · 
125 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Conventional magnetic resonance imaging (MRI) assesses neurodegenerative structural changes in the cerebral anatomy of Parkinson's disease (PD) patients but cannot detect non-structural abnormalities; however, enhanced T2 star weighted angiography (ESWAN) can precisely indicate PD-related substantia nigra (SN) iron deposition. The differences in ESWAN-based parameters between different PD stages were assessed using midbrain iron deposits of 20 PD patients aged 64.3±12.7 (41-85) years grouped by Hoehn and Yahr staging into minimal (stages ≤2.5) or moderate to severe (stages ≥3.0) motor impairment groups and 14 healthy control subjects. Conventional MRI and ESWAN measurements of mean phase value (MPV) and midbrain dimensions (width and diameter) revealed similar anatomical characteristics; however, ESWAN revealed the presence of smaller MPVs and SN pars compacta (SNc) (P<0.01) and a negative correlation between reduction extent and motor impairment (P<0.01). SNc width to midbrain diameter was reduced in moderate to severe impairment patients versus control and minimal impairment patients (both P<0.01). A positive correlation was found between MPV and width or SNc width to midbrain diameter ratio (P<0.01 and P<0.05, respectively). Minimal impairment group mean MPV and substantia nigra pars reticulata (SNr) width evidenced no significant reduction, unlike significant reductions in the moderate to severe impairment group (P<0.01). No significant changes were observed in MPV or width in the RN region (P>0.05). ESWAN allows for early and accurate iron deposition determination in PD patients, particularly useful as a supplement to conventional MRI in early-stage PD patients.
    Magnetic Resonance Imaging 06/2013; · 2.06 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: INTRODUCTION: Evaluation of intratumoral-susceptibility-signals (ITSS) in susceptibility-weighted-imaging (SWI) has been reported to improve diagnostic performance for solitary enhancing brain lesions. Due to the distinct morphologic variability of ITSS, standardized evaluation proved to be difficult. We analyzed, if a new postprocessing method using percentagewise quantification (PQ) of ITSS enables differentiation between different entities of cerebral metastases and may thus improve differential diagnosis in cases of unknown primary. MATERIALS AND METHODS: SWI and contrast enhanced T1-weighted MR images were acquired from 84 patients with intracerebral metastases (20 patients with mamma carcinoma (MC), 15 patients with malignant melanoma (MM), 49 patients with bronchial carcinoma (BC)) at 3Tesla MR. Images were co-registered and enhancing lesions were delineated on T1-weighted images and the outline transferred to the corresponding SWI map. All voxels within the lesion presenting values below a reference value placed in the ventricular system were determined and percentagewise calculated. RESULTS: Diagnostic performance of percentagewise quantification (PQ) of ITSS, as determined with area under the receiver operating characteristic curve (AUC) was excellent (AUC=0.96; 95% confidence interval (CI) 0.90, 1.00) to discriminate MM from MC, good for the discrimination of MM and BC (AUC=0.81, 95% CI 0.70, 0.92) and poor for the discrimination of MC and BC (AUC=0.60; 95% CI 0.47, 0.73). CONCLUSION: PQ is a new approach for the assessment of SWI that can be used for differential diagnosis of intracerebral metastases. Metastases of MM and MC or BC can be distinguished with high sensitivity and specificity.
    European journal of radiology 07/2012; · 2.65 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: MR imaging without and with gadolinium-based contrast agents (GBCAs) is an important imaging tool for defining normal anatomy and characteristics of lesions. GBCAs have been used in contrast-enhanced MR imaging in defining and characterizing lesions of the central nervous system for more than 20 years. The combination of unenhanced and GBCA-enhanced MR imaging is the clinical gold standard for the noninvasive detection and delineation of most intracranial and spinal lesions. MR imaging has a high predictive value that rules out neoplasm and most inflammatory and demyelinating processes of the central nervous system.
    Magnetic resonance imaging clinics of North America 11/2012; 20(4):649-85.