Nicoletta Anzalone

Perfusion MRI: The Five Most Frequently Asked Technical Questions

OBJECTIVE This and its companion article address the 10 most frequently asked questions that radiologists face when planning, performing, processing, and interpreting different MR perfusion studies in CNS imaging. CONCLUSION Perfusion MRI is a promising tool in assessing stroke, brain tumors, and patients with neurodegenerative diseases. Most of the impediments that have limited the use of perfusion MRI can be overcome to allow integration of these methods into modern neuroimaging protocols.

MR imaging in multiple sclerosis: review and recommendations for current practice

SUMMARY: MR imaging is widely used for the diagnosis and monitoring of patients with MS. Applications and protocols for MR imaging continue to evolve, prompting a need for continual reassessments of the optimal use of this technique in clinical practice. This article provides updated recommendations on the use of MR imaging in MS, based on a review of the trial evidence and personal experiences shared at a recent expert meeting of radiologists and neurologists.

MR imaging of neoplastic central nervous system lesions: review and recommendations for current practice.

SUMMARY: MR imaging is the preferred technique for the diagnosis, treatment planning, and monitoring of patients with neoplastic CNS lesions. Conventional MR imaging, with gadolinium-based contrast enhancement, is increasingly combined with advanced, functional MR imaging techniques to offer morphologic, metabolic, and physiologic information. This article provides updated recommendations to neuroradiologists, neuro-oncologists, neurosurgeons, and radiation oncologists on the practical applications of MR imaging of neoplastic CNS lesions in adults, with particular focus on gliomas, based on a review of the clinical trial evidence and personal experiences shared at a recent international meeting of experts in neuroradiology, neuro-oncology, neurosurgery, and radio-oncology.

Follow-Up of Coiled Cerebral Aneurysms at 3T: Comparison of 3D Time-of-Flight MR Angiography and Contrast-Enhanced MR Angiography

BACKGROUND AND PURPOSE: Our aim was to compare contrast-enhanced MR angiography (CE-MRA) and 3D time-of-flight (TOF) MRA at 3T for follow-up of coiled cerebral aneurysms. MATERIALS AND METHODS: Fifty-two patients treated with Guglielmi detachable coils for 54 cerebral aneurysms were evaluated at 3T MRA. 3D TOF MRA (TR/TE = 23/3.5; SENSE factor = 2.5) and CE-MRA by using a 3D ultrafast gradient-echo sequence (TR/TE = 5.9/1.8; SENSE factor = 3) enhanced with 0.1-mmol/kg gadobenate dimeglumine were performed in the same session. Source images, 3D maximum intensity projection, 3D shaded surface display, and/or 3D volume-rendered reconstructions were evaluated in terms of aneurysm occlusion/patency and artifact presence. RESULTS: In terms of clinical classification, the 2 MRA sequences were equivalent for 53 of the 54 treated aneurysms: 21 were considered fully occluded, whereas 16 were considered to have a residual neck and 16 were considered residually patent at follow-up MRA. The remaining aneurysm appeared fully occluded at TOF MRA but had a residual patent neck at CE-MRA. Visualization of residual aneurysm patency was significantly (P = .001) better with CE-MRA compared with TOF MRA for 10 (31.3%) of the 32 treated aneurysms considered residually patent with both sequences. Coil artifacts were present in 5 cases at TOF MRA but in none at CE-MRA. No relationship was apparent between the visualization of patency and either the size of the aneurysm or the interval between embolization and follow-up. CONCLUSION: At follow-up MRA at 3T, unenhanced TOF and CE-MRA sequences are similarly effective at classifying coiled aneurysms as occluded or residually patent. However, CE-MRA is superior to TOF MRA for visualization of residual patency and is associated with fewer artifacts.

Acute subarachnoid Haemorrhage: 3D time-of-flight MR angiography versus intra-arterial digital angiography

To evaluate the efficacy and reliability of 3D time-of-flight MR angiography (TOF MRA) as a noninvasive procedure, 27 patients with acute subarachnoid haemorrhage (SAH) were studied with MRA immediately before or after intra-arterial digital subtraction angiography (DSA). 3DTOF MRA was performed with an axial slab of 60 mm centred on the circle of Willis and isotropic voxels. DSA showed 22 aneurysms and 1 dural arteriovenous fistula in 21 patients; the aneurysms ranged in size from 2 to 8 mm. MRA failed to show 2 small aneurysms, at the origin of the posterior and anterior communicating arteries. The 3D display of the intracranial vessels obtained with maximum intensity projection (MIP) or targetted MIP sometimes rendered the aneurysms better than DSA. However, due to its high spatial resolution, DSA more clearly defined the overall anatomy of the walls of the normal and abnormal vessels.

Detection of Cerebral Metastases on Magnetic Resonance Imaging: Intraindividual Comparison of Gadobutrol with Gadopentetate Dimeglumine

Background: Contrast-enhanced magnetic resonance (MR) imaging with gadolinium-based contrast agents is widely used for the detection of cerebral metastases with standard contrast agents. Newer developments in MR contrast agents have led to a higher relaxivity and/or concentration for these agents. Purpose: To assess the effectiveness of a standard dose of 1.0 M gadobutrol compared with a standard dose of gadopentetate dimeglumine for the MR detection of brain metastases. Material and Methods: 27 patients with at least one cerebral metastasis were examined twice with contrast-enhanced MR imaging, using gadobutrol at 0.1 ml/kg and gadopentetate dimeglumine at 0.2 ml/kg (i.e., identical gadolinium dosage of 0.1 mmol/kg bodyweight). The interval between examinations was 18 hours, and the order of injection was fully randomized. Images were acquired using a three-dimensional (3D) fast gradient echo sequence, and evaluated in blinded fashion by two experienced neuroradiologists in consensus in terms of the total number of lesions detected at each examination in each patient and qualitatively in terms of the lesion conspicuity observed. Results: A total of 67 lesions were detected after gadobutrol compared with 65 lesions detected after gadopentetate dimeglumine. In two patients, a lesion was seen only after gadobutrol. Qualitative comparison of images revealed improved lesion conspicuity after gadobutrol in 10/27 cases compared with 0/27 cases after gadopentetate dimeglumine, and equivalent conspicuity in 17/27 cases (P=0.002, gadobutrol vs. gadopentetate dimeglumine). Conclusion:At equal gadolinium dosage, gadobutrol appears to offer significant advantages over gadopentetate dimeglumine for the visualization of brain metastases, with particular benefit for improving the conspicuity of detected lesions.

Principles of T2 *-weighted dynamic susceptibility contrast MRI technique in brain tumor imaging.

Dynamic susceptibility contrast magnetic resonance imaging (DSC‐MRI) is used to track the first pass of an exogenous, paramagnetic, nondiffusible contrast agent through brain tissue, and has emerged as a powerful tool in the characterization of brain tumor hemodynamics. DSC‐MRI parameters can be helpful in many aspects, including tumor grading, prediction of treatment response, likelihood of malignant transformation, discrimination between tumor recurrence and radiation necrosis, and differentiation between true early progression and pseudoprogression. This review aims to provide a conceptual overview of the underlying principles of DSC‐MRI of the brain for clinical neuroradiologists, scientists, or students wishing to improve their understanding of the technical aspects, pitfalls, and controversies of DSC perfusion MRI of the brain. Future consensus on image acquisition parameters and postprocessing of DSC‐MRI will most likely allow this technique to be evaluated and used in high‐quality multicenter studies and ultimately help guide clinical care. J. Magn. Reson. Imaging 2015;41:296–313.© 2013 Wiley Periodicals, Inc.

Cerebral neoplastic enhancing lesions: Multicenter, randomized, crossover intraindividual comparison between gadobutrol (1.0 M) and gadoterate meglumine (0.5 M) at 0.1 mmol Gd/kg body weight in a clinical setting

OBJECTIVE Two macrocyclic extracellular contrast agents, one-molar neutral gadobutrol and ionic gadoterate meglumine, were compared to determine the overall preference for one or the other in a clinical setting. MATERIALS AND METHODS Multicenter, randomized, single-blind, intra-individually controlled, comparison study with a corresponding blinded read. Efficacy analysis was based on 136 patients who underwent identical MRI examinations: group A first received 1.0M gadobutrol followed by 0.5M gadoterate meglumine 48 h to 7 days later; group B had a reversed administration order. Three independent blinded readers assessed off-site their overall diagnostic preference (primary efficacy parameter) based on a matched pairs approach. RESULTS Superiority of gadobutrol over gadoterate meglumine was demonstrated for the qualitative assessment of overall preference across all readers by a statistically significant difference between both contrast agents for this primary endpoint. Preferences in lesion enhancement (secondary endpoint) were also found significantly in favor of gadobutrol. For preference in lesion delineation from surrounding tissue/edema and for internal structure only a trend towards a higher proportion for gadobutrol was found (except for internal structure reported by one reader, which showed a result of statistical significance). Lesion contrast and relative lesion enhancement (quantitative parameters) were statistically significantly higher for gadobutrol compared to gadoterate meglumine. CONCLUSION Contrast-enhanced MRI of neoplastic brain lesions at a dose of 0.1 mmol Gd/kg body weight, assessed in a standardized off-site blinded reading, results in a significantly higher qualitative and quantitative preference for gadobutrol compared to gadoterate meglumine.

Follow-up of coiled cerebral aneurysms: comparison of three-dimensional time-of-flight magnetic resonance angiography at 3 tesla with three-dimensional time-of-flight magnetic resonance angiography and contrast-enhanced magnetic resonance angiography at 1.5 Tesla.

Objectives:To compare three-dimensional (3D) time-of-flight (TOF)-magnetic resonance angiography (MRA) at 3 T with 3D TOF-MRA and ultrafast contrast-enhanced (CE)-MRA at 1.5 T and to determine the optimum MRA sequence for follow-up of cerebral aneurysms treated with Guglielmi detachable coils (GDCs). Material and Methods:Twenty-eight patients treated with GDCs for 29 cerebral aneurysms underwent MRA at 3 T and 1.5 T within 24 hours (during the same session for outpatients). All imaging was performed using a sensitivity-encoding head coil (SENSE factor = 2). Unenhanced axial 3D TOF-MRA at 3 T was performed with repetition time (TR)/echo time (TE) = 16/2.9. At 1.5 T, axial 3D TOF-MRA (TR/TE = 23/4) was performed first, followed by axial 3D ultrafast gradient echo MRA (TR/TE = 6/2) enhanced with 0.1 mmol/kg gadobenate dimeglumine (MultiHance). Source images and maximum intensity projection and shaded surface display reconstructions for each acquisition sequence were evaluated for quality of visualization of residual aneurysm patency and scored for visualization preference. Results:Residual aneurysm was detected in 15/29 cases on CE-MRA at 1.5 T and TOF-MRA at 3 T but in only 11/29 cases on TOF-MRA at 1.5 T. CE-MRA at 1.5 T was preferred to TOF-MRA at 1.5 T in 13 cases (P = 0.004) and to TOF-MRA at 3 T in 3 cases. TOF-MRA at 3 T was preferred to TOF-MRA at 1.5 T in 11 cases (P = 0.04) but was not preferred to CE-MRA at 1.5 T in any case. The parent artery was identifiable in all 29 cases after TOF-MRA at 3 T and CE-MRA at 1.5 T but in only 27 cases after 3D TOF-MRA at 1.5 T. Conclusions:TOF-MRA follow-up of coiled aneurysms is better at 3 T than at 1.5 T; nevertheless, greater definition of residual patency is achieved with ultrafast CE-MRA at 1.5 T.

A case-control study of transient global amnesia.

To evaluate risk factors and prognosis of transient global amnesia (TGA), three groups of 30 subjects each affected respectively by: (1) first-ever TGA; (2) first-ever transient ischaemic attack (TIA); (3) depressive neurosis, were compared. Prevalence of cerebrovascular risk factors was similar in patients with TGA and TIA, but significantly lower in the third group. CT showed more hypodense lesions in TIA patients than in those with TGA. In a mean follow-up of 36 months, five TGA patients experienced a TIA and three others had recurrence of TGA, but none suffered stroke or myocardial infarction. In the TIA group, four had recurrence of TIA, two suffered a stroke and two others a myocardial infarction, whereas none had TGA attacks. None of the patients of the third group had any ischaemic event during follow-up. The similar prevalence of risk factors, but the different prognosis between TGA and TIA patients, suggest that TGA is an ischaemic event, probably not triggered by thromboembolism but by a different, possibly vasospastic, mechanism.