Multi-sequence Magnetic Resonance Imaging Research Articles

The Utility of Noncontrast Multisequence Magnetic Resonance Imaging to Identify Venous Thrombi Suitable for Lysis

The Utility of Noncontrast Multisequence Magnetic Resonance Imaging to Identify Venous Thrombi Suitable for Lysis

Relating multi-sequence longitudinal intensity profiles and clinical covariates in incident multiple sclerosis lesions.

The formation of multiple sclerosis (MS) lesions is a complex process involving inflammation, tissue damage, and tissue repair — all of which are visible on structural magnetic resonance imaging (MRI) and potentially modifiable by pharmacological therapy. In this paper, we introduce two statistical models for relating voxel-level, longitudinal, multi-sequence structural MRI intensities within MS lesions to clinical information and therapeutic interventions: (1) a principal component analysis (PCA) and regression model and (2) function-on-scalar regression models. To do so, we first characterize the post-lesion incidence repair process on longitudinal, multi-sequence structural MRI from 34 MS patients as voxel-level intensity profiles. For the PCA regression model, we perform PCA on the intensity profiles to develop a voxel-level biomarker for identifying slow and persistent, long-term intensity changes within lesion tissue voxels. The proposed biomarker's ability to identify such effects is validated by two experienced clinicians (a neuroradiologist and a neurologist). On a scale of 1 to 4, with 4 being the highest quality, the neuroradiologist gave the score on the first PC a median quality rating of 4 (95% CI: [4,4]), and the neurologist gave the score a median rating of 3 (95% CI: [3,3]). We then relate the biomarker to the clinical information in a mixed model framework. Treatment with disease-modifying therapies (p < 0.01), steroids (p < 0.01), and being closer to the boundary of abnormal signal intensity (p < 0.01) are all associated with return of a voxel to an intensity value closer to that of normal-appearing tissue. The function-on-scalar regression model allows for assessment of the post-incidence time points at which the covariates are associated with the profiles. In the function-on-scalar regression, both age and distance to the boundary were found to have a statistically significant association with the lesion intensities at some time point. The two models presented in this article show promise for understanding the mechanisms of tissue damage in MS and for evaluating the impact of treatments for the disease in clinical trials.

Classification of multiple sclerosis lesions using adaptive dictionary learning

This paper presents a sparse representation and an adaptive dictionary learning based method for automated classification of multiple sclerosis (MS) lesions in magnetic resonance (MR) images. Manual delineation of MS lesions is a time-consuming task, requiring neuroradiology experts to analyze huge volume of MR data. This, in addition to the high intra- and inter-observer variability necessitates the requirement of automated MS lesion classification methods. Among many image representation models and classification methods that can be used for such purpose, we investigate the use of sparse modeling. In the recent years, sparse representation has evolved as a tool in modeling data using a few basis elements of an over-complete dictionary and has found applications in many image processing tasks including classification. We propose a supervised classification approach by learning dictionaries specific to the lesions and individual healthy brain tissues, which include white matter (WM), gray matter (GM) and cerebrospinal fluid (CSF). The size of the dictionaries learned for each class plays a major role in data representation but it is an even more crucial element in the case of competitive classification. Our approach adapts the size of the dictionary for each class, depending on the complexity of the underlying data. The algorithm is validated using 52 multi-sequence MR images acquired from 13 MS patients. The results demonstrate the effectiveness of our approach in MS lesion classification.

Detection of Vessel Wall Lesions in Spontaneous Symptomatic Vertebrobasilar Artery Dissection Using T1-weighted 3-dimensional Imaging

Spontaneous intracranial vertebrobasilar artery dissection (iVBD) is a cause of ischemic stroke and subarachnoid hemorrhage in young adults that can be detected noninvasively by using multisequence magnetic resonance imaging (MRI). However, MRI findings are sometimes difficult to interpret, and its accuracy tends to be suboptimal, especially during the acute period. Therefore, we investigated whether 3-dimensional (3D) vessel wall imaging (VWI) technique could readily detect iVBD lesions in acute phase patients. Sixteen consecutive patients with acute ischemic stroke caused by iVBD were prospectively examined with a 1.5-T magnetic resonance scanner. T1-weighted (T1W) 3D-VWI was obtained using a flow-sensitized 3D fast spin-echo technique. In addition, multisequence MRI comprising magnetic resonance angiography (MRA), basiparallel anatomical scanning (BPAS), and axial T1W imaging (T1WI) were also examined. Presence of luminal stenosis, aneurysmal dilatation, intramural high signal, and intimal flap/double lumen of the vertebral and basilar arteries were visually assessed using each technique. On 3D-VWI, luminal stenosis, aneurysmal dilatation, intramural high signal, and intimal flap were observed in 16 (100%), 11 (68.8%), 16 (100%), and 1 (6.3%) patients, respectively. In contrast, on conventional techniques, these findings were observed in 15 (93.8%, MRA with BPAS), 12 (75.0%, MRA with BPAS), 12 (75.0%, T1WI), and 12 (75.0%, MRA) patients, respectively. The T1W 3D-VWI can directly visualize vessel wall iVBD lesions during the acute period of stroke compared with multisequence MRI.

Thalamotemporal impairment in temporal lobe epilepsy: A combined MRI analysis of structure, integrity, and connectivity

ObjectiveThalamic abnormality in temporal lobe epilepsy (TLE) is well known from imaging studies, but evidence is lacking regarding connectivity profiles of the thalamus and their involvement in the disease process. We used a novel multisequence magnetic resonance imaging (MRI) protocol to elucidate the relationship between mesial temporal and thalamic pathology in TLE.MethodsFor 23 patients with TLE and 23 healthy controls, we performed T1-weighted (for analysis of tissue structure), diffusion tensor imaging (tissue connectivity), and T1 and T2 relaxation (tissue integrity) MRI across the whole brain. We used connectivity-based segmentation to determine connectivity patterns of thalamus to ipsilateral cortical regions (occipital, parietal, prefrontal, postcentral, precentral, and temporal). We subsequently determined volumes, mean tractography streamlines, and mean T1 and T2 relaxometry values for each thalamic segment preferentially connecting to a given cortical region, and of the hippocampus and entorhinal cortex.ResultsAs expected, patients had significant volume reduction and increased T2 relaxation time in ipsilateral hippocampus and entorhinal cortex. There was bilateral volume loss, mean streamline reduction, and T2 increase of the thalamic segment preferentially connected to temporal lobe, corresponding to anterior, dorsomedial, and pulvinar thalamic regions, with no evidence of significant change in any other thalamic segments. Left and right thalamotemporal segment volume and T2 were significantly correlated with volume and T2 of ipsilateral (epileptogenic), but not contralateral (nonepileptogenic), mesial temporal structures.SignificanceThese convergent and robust data indicate that thalamic abnormality in TLE is restricted to the area of the thalamus that is preferentially connected to the epileptogenic temporal lobe. The degree of thalamic pathology is related to the extent of mesial temporal lobe damage in TLE.

The influence of computational strategy on prediction of mechanical stress in carotid atherosclerotic plaques: Comparison of 2D structure-only, 3D structure-only, one-way and fully coupled fluid-structure interaction analyses

BackgroundCompositional and morphological features of carotid atherosclerotic plaques provide complementary information to luminal stenosis in predicting clinical presentations. However, they alone cannot predict cerebrovascular risk. Mechanical stress within the plaque induced by cyclical changes in blood pressure has potential to assess plaque vulnerability. Various modeling strategies have been employed to predict stress, including 2D and 3D structure-only, 3D one-way and fully coupled fluid-structure interaction (FSI) simulations. However, differences in stress predictions using different strategies have not been assessed. MethodsMaximum principal stress (Stress-P1) within 8 human carotid atherosclerotic plaques was calculated based on geometry reconstructed from in vivo computerized tomography and high resolution, multi-sequence magnetic resonance images. Stress-P1 within the diseased region predicted by 2D and 3D structure-only, and 3D one-way FSI simulations were compared to 3D fully coupled FSI analysis. ResultsCompared to 3D fully coupled FSI, 2D structure-only simulation significantly overestimated stress level (94.1kPa [65.2, 117.3] vs. 85.5kPa [64.4, 113.6]; median [inter-quartile range], p=0.0004). However, when slices around the bifurcation region were excluded, stresses predicted by 2D structure-only simulations showed a good correlation (R2=0.69) with values obtained from 3D fully coupled FSI analysis. 3D structure-only model produced a small yet statistically significant stress overestimation compared to 3D fully coupled FSI (86.8kPa [66.3, 115.8] vs. 85.5kPa [64.4, 113.6]; p<0.0001). In contrast, one-way FSI underestimated stress compared to 3D fully coupled FSI (78.8kPa [61.1, 100.4] vs. 85.5kPa [64.4, 113.7]; p<0.0001). ConclusionsA 3D structure-only model seems to be a computationally inexpensive yet reasonably accurate approximation for stress within carotid atherosclerotic plaques with mild to moderate luminal stenosis as compared to fully coupled FSI analysis.

Intraplaque stretch in carotid atherosclerotic plaque--an effective biomechanical predictor for subsequent cerebrovascular ischemic events.

BackgroundStretch is a mechanical parameter, which has been proposed previously to affect the biological activities in different tissues. This study explored its utility in determining plaque vulnerability.MethodsOne hundred and six patients with mild to moderate carotid stenosis were recruited in this study (53 symptomatic and 53 asymptomatic). High resolution, multi-sequence magnetic resonance (MR) imaging was performed to delineate various plaque components. Finite element method was used to predict high stretch concentration within the plaque.ResultsDuring a two-year follow-up, 11 patients in symptomatic group and 3 in asymptomatic group experienced recurrent cerebrovascular events. Plaque stretch at systole and stretch variation during one cardiac cycle was greater in symptomatic group than those in the asymptomatic. Within the symptomatic group, a similar trend was observed in patients with recurrent events compared to those without.ConclusionPlaques with high stretch concentration and large stretch variation are associated with increased risk of future cerebrovascular events.

Conspicuity of bone metastases on fast Dixon-based multisequence whole-body MRI: Clinical utility per sequence

PurposeThe purpose of the study was to evaluate the conspicuity of bone metastases on each of the numerous sequences produced by fast Dixon-based multisequence whole-body (WB) magnetic resonance imaging (MRI) scanning in order to determine the most clinically useful sequences overall and per anatomic region. Materials and MethodsTwenty-seven breast cancer patients with bone metastases were prospectively studied with fast Dixon-based WB MRI including head/neck, chest, abdominal, pelvic, thigh, calf/feet and either cervical, thoracic and lumbar or cervical/thoracic and thoracic/lumbar regions. Sequences included coronal T2, axial T1 without and with intravenous gadolinium (+C), sagittal T1 spine+C, each associated fat-only (FO) and fat-saturated (FS) sequence, axial diffusion-weighted imaging (DWI) and short tau inversion recovery (STIR). Blinded reviewers evaluated lesion conspicuity, a surrogate of clinical utility, on a five-point scale per anatomic region. Sequences were compared using analysis of variance, differences were detected with Tukey's honestly significant difference test, and the four sequences with highest mean conspicuity were compared to the remainder overall and per anatomic region. ResultsOverall, a significant lesion conspicuity difference was found (P<.0001), and lesion conspicuity was significantly higher on FS T1+C, FO T1+C, T1+C sagittal and FS T1+C axial sequences (P<.0001). Per-region results were the same in the head/neck. Other sequences overlapped with these and included the following: chest/abdomen — FO T2, DWI; pelvis — DWI, FO T2; thigh — FS T2, FO T2, FO T1+C; calf/feet — FS T2, DWI, FO T2, STIR. ConclusionOverall, bone lesions were most conspicuous on FS T1+C sagittal, FO T1+C sagittal, T1+C sagittal and FS T1+C axial fast Dixon WB MRI sequences.

Therapeutic imaging window of cerebral infarction revealed by multisequence magnetic resonance imaging: An animal and clinical study.

In this study, we established a Wistar rat model of right middle cerebral artery occlusion and observed pathological imaging changes (T2-weighted imaging [T2WI], T2FLAIR, and diffusion-weighted imaging [DWI]) following cerebral infarction. The pathological changes were divided into three phases: early cerebral infarction, middle cerebral infarction, and late cerebral infarction. In the early cerebral infarction phase (less than 2 hours post-infarction), there was evidence of intracellular edema, which improved after reperfusion. This improvement was defined as the ischemic penumbra. In this phase, a high DWI signal and a low apparent diffusion coefficient were observed in the right basal ganglia region. By contrast, there were no abnormal T2WI and T2FLAIR signals. For the middle cerebral infarction phase (2–4 hours post-infarction), a mixed edema was observed. After reperfusion, there was a mild improvement in cell edema, while the angioedema became more serious. A high DWI signal and a low apparent diffusion coefficient signal were observed, and some rats showed high T2WI and T2FLAIR signals. For the late cerebral infarction phase (4–6 hours post-infarction), significant angioedema was visible in the infarction site. After reperfusion, there was a significant increase in angioedema, while there was evidence of hemorrhage and necrosis. A mixed signal was observed on DWI, while a high apparent diffusion coefficient signal, a high T2WI signal, and a high T2FLAIR signal were also observed. All 86 cerebral infarction patients were subjected to T2WI, T2FLAIR, and DWI. MRI results of clinic data similar to the early infarction phase of animal experiments were found in 51 patients, for which 10 patients (10/51) had an onset time greater than 6 hours. A total of 35 patients had MRI results similar to the middle and late infarction phase of animal experiments, of which eight patients (8/35) had an onset time less than 6 hours. These data suggest that defining the “therapeutic time window” as the time 6 hours after infarction may not be suitable for all patients. Integrated application of MRI sequences including T2WI, T2FLAIR, DW-MRI, and apparent diffusion coefficient mapping should be used to examine the ischemic penumbra, which may provide valuable information for identifying the “therapeutic time window”.

A Novel MRI Technique for Adaptive Cervix Cancer Brachytherapy

Published guidelines for image-guided brachytherapy (IGBT) of cervix cancer recommend the use of T2-weighted (T2W) magnetic resonance imaging (MRI). Here, we introduce a novel method for MRI-guided IGBT that incorporates the use of multiple MRI sequences: T2W imaging, proton density weighted (PDW) imaging, and diffusion weighted-apparent diffusion coefficient (DW-ADC) mapping. We demonstrate how use of this multi-sequence MRI technique can facilitate adaptive planning over the course of treatment.

Long-Term Decrease in Bladder Cancer Recurrence with Hexaminolevulinate Enabled Fluorescence Cystoscopy

We assessed the impact of hexaminolevulinate fluorescence cystoscopic detection of papillary, nonmuscle invasive bladder cancer on the long-term recurrence rate. Long-term followup was assessed in 551 participants enrolled in a prospective, randomized study of fluorescence cystoscopy for Ta or T1 urothelial bladder cancer. In the original study 280 patients in the white light cystoscopy group and 271 in the fluorescence cystoscopy group were followed with cystoscopy for 3, 6 and 9 months after initial resection or until recurrence. A study extension protocol was done for long-term followup of these patients. Followup information was obtained for 261 of the 280 patients (93%) in the white light group and 255 of the 271 (94%) in the fluorescence group. Median followup in the white light and fluorescence groups was 53.0 and 55.1 months, and 83 (31.8%) and 97 patients (38%) remained tumor free, respectively. Median time to recurrence was 9.4 months in the white light group and 16.4 months in the fluorescence group (p = 0.04). The intravesical therapy rate was similar in the 2 groups (46% and 45%, respectively). Cystectomy was done in 22 of 280 cases (7.9%) in the white light group and in 13 of the 271 (4.8%) in the fluorescence group (p = 0.16). Hexaminolevulinate fluorescence cystoscopy significantly improves long-term bladder cancer time to recurrence with a trend toward improved bladder preservation.

Accuracy, intermethod agreement, and inter-reviewer agreement for use of magnetic resonance imaging and myelography in small-breed dogs with naturally occurring first-time intervertebral disk extrusion

To determine accuracy, intermethod agreement, and inter-reviewer agreement for multisequence magnetic resonance imaging (MRI) and 2-view orthogonal myelography in small-breed dogs with first-time intervertebral disk (IVD) extrusion. Prospective evaluation study. 24 dogs with thoracolumbar IVD extrusion. Each dog underwent MRI and myelography. Images obtained with each modality were independently evaluated and assigned standardized scores in a blinded manner by 3 reviewers. Results were compared with surgical findings. Inter-reviewer and intermethod agreements were assessed via κ statistics. Accuracy was assessed as the percentage of dogs for which ≥ 2 of 3 reviewers recorded findings identical to those determined surgically. Inter-reviewer agreement was substantial for site (κ = 0.70) and side of IVD extrusion (κ = 0.62) in T2-weighted magnetic resonance images and was substantial for site (κ = 0.72) and fair for side of extrusion (κ = 0.37) in myelographic images. Agreement for site between each modality and surgical findings was near perfect (κ = 0.94 and 0.88 for MRI and myelography, respectively). Intermethod agreement was substantial for site (κ = 0.71) and moderate for side of extrusion (κ = 0.40). Accuracy of MRI for site and side was 100% when results for T1-weighted, T2-weighted, and contrast-enhanced T1-weighted sequences were combined. Accuracy of myelography was 90.9% and 54.5% for site and side, respectively. Agreement between imaging results and surgical findings for identification of IVD extrusion sites in small-breed dogs was similar for MRI and myelography. However, MRI appeared to be more accurate than myelography and allowed evaluation of extradural compressive mass composition.

Carotid Plaques in Transient Ischemic Attack and Stroke Patients

To investigate the natural course of carotid plaque progression in transient ischemic attack/stroke patients by using serial multisequence magnetic resonance imaging (MRI). Forty transient ischemic attack/stroke patients with ipsilateral <70% carotid stenosis underwent MRI of the plaque ipsilateral to the symptomatic side at baseline and after 1 year. The MRI protocol consisted of T1-weighted turbo field-echo, time-of-flight, T2-weighted turbo spin-echo (TSE), and pre- and postgadopentetate dimeglumine-enhanced T1-weighted TSE images. For each plaque, carotid lumen volume, wall volume, total vessel volume (=carotid lumen volume + wall volume), the presence of a lipid-rich necrotic core (LRNC), fibrous cap (FC) status, and the presence of intraplaque hemorrhage (IPH) were assessed at both time points. Over a 1-year period, mean carotid lumen volume decreased with 4.8% ± 2.0% (±standard error) (P = 0.013). Mean wall volume increased with 11.2% ± 2.2% (P < 0.001). Total vessel volume did not significantly change (P = 0.147). At baseline, there were 18 plaques with a LRNC, which also had a LRNC at 1-year follow-up. No plaque without a LRNC at baseline developed a LRNC during the follow-up period. All plaques with a LRNC had a thin and/or ruptured FC at both time points. Twelve patients had IPH both at baseline and at follow-up. In one patient, IPH disappeared, whereas in another patient, new IPH appeared at follow-up. The presence of IPH and a LRNC with a thin and/or ruptured FC were not significantly associated with plaque progression (P > 0.05). In symptomatic patients with an ipsilateral carotid plaque causing <70% stenosis, we found evidence for inward plaque remodeling over a 1-year period. Overall, the presence/absence of IPH, a LRNC, and FC status did not change over 1 year.

Pathophysiology and Long‐Term Outcome of Reversible Tumor‐Like Lesions Induced by Presenting Status Epilepticus

Within the spectrum of reversible neuroimaging abnormalities induced by status epilepticus (SE) tumor-like lesions (TLL) have been rarely described. Their etiology, pathophysiology, and long-term outcome remain uncertain. These issues could be clarified by long-term magnetic resonance imaging (MRI) studies in TLL induced by presenting SE. Prospective multi-sequence MRI and clinical and electroencephalographic long-term (18 to 60 months) follow-up studies were performed in 3 patients with reversible TLL induced by presenting SE. In the peri-ictal MRI, TLL are hypointense in T1-weighted, hyperintense in T2-weighted, and fluid-attenuated inversion recovery images with a marked subcortical component and sulci effacement. The diffusion and MR-spectroscopy studies disclosed intermixed areas of increased/decreased diffusivity associated with a lactate peak and a decreased N-acetylaspartate. At long-term follow-up, none of the patients had seizure recurrence or electroencephalographic epileptiform abnormalities; MRI showed residual focal atrophy and gliosis associated with neuronal loss/dysfunction. SE per se may induce TLL. MRI multi-sequence studies disclosed that they are mainly formed by focal vasogenic and cytotoxic edema resulting from the hypermetabolism associated with seizure activity. In spite of a clinical favorable long-term outcome, the demonstration of irreversible brain damage argues in favor of immediate treatment of SE.

MP-21.13: Accuracy of Multi-sequence Magnetic Resonance Imaging of Radio-recurrent Prostate Cancer

MP-21.13: Accuracy of Multi-sequence Magnetic Resonance Imaging of Radio-recurrent Prostate Cancer

Diagnostic Imaging of Patients in a Memory Clinic: Comparison of MR Imaging and 64–Detector Row CT

To investigate the assessment of global cortical atrophy (GCA), medial temporal lobe atrophy (MTA), and white matter changes (WMCs) in patients screened at a memory clinic with a 64-detector row computed tomography (CT) brain protocol, in comparison with the reference standard, magnetic resonance (MR) imaging. The study protocol was approved by the local institutional review board. Written informed consent was obtained from all participants. Thirty patients (21 men, nine women; median age, 62 years) who presented to a memory clinic underwent 64-detector row CT and multisequence MR imaging of the brain on the same day. Three readers blinded to the clinical diagnosis assessed the resultant images. Images were presented in random order and scored for GCA, MTA, and WMC with published visual rating scales. Intermodality agreement between CT and MR imaging (intrareader agreement across both modalities), expressed by weighted kappa analysis, and interobserver agreement within each modality between readers (Kendall W test) were assessed. Overall, excellent intraobserver agreement between CT and MR imaging was observed for GCA (mean kappa, 0.83) and MTA (mean kappa, 0.88 and 0.86 on the left and right sides of the brain, respectively). There was substantial overall agreement concerning WMC (mean kappa, 0.79). For all three tested scales, interobserver variability was low and comparable for CT and MR imaging. Use of 64-detector row brain CT yields reliable information that is comparable with that obtained with MR imaging. Thus, multidetector row CT is a suitable diagnostic imaging tool in a memory clinic setting.

White Matter Microstructural Integrity and Cognitive Function in a General Elderly Population

The role of macrostructural white matter changes, such as atrophy and white matter lesions, in cognitive decline is increasingly being recognized. However, in the elderly population, these macrostructural changes do not account for all variability in cognition. Measures reflecting white matter microstructural integrity may provide additional information to investigate the relation between white matter changes and cognition. To study the relation between white matter integrity and cognition in the general elderly population, using diffusion tensor imaging and taking into account macrostructural white matter changes. Cross-sectional population-based study. A general community in the Netherlands. A population-based sample of 860 persons, older than 60 years, free of dementia. We performed multisequence magnetic resonance imaging, which included diffusion tensor imaging, and extensive neuropsychological testing. Fractional anisotropy, mean diffusivity, and directional diffusivities were measured globally in white matter lesions and normal-appearing white matter. Performance on neuropsychological tests in the following cognitive domains: memory, executive function, information processing speed, global cognition, and motor speed. Regardless of macrostructural white matter changes, a higher mean diffusivity or higher axial and radial diffusivities within white matter lesions or normal-appearing white matter were related to worse performance on tasks assessing information processing speed and global cognition. In addition, diffusivity within white matter lesions related to memory, while in normal-appearing white matter, it furthermore related to executive function. Lower mean fractional anisotropy in white matter lesions or normal-appearing white matter related to worse information processing speed and motor speed. Microstructural integrity of both white matter lesions and normal-appearing white matter is associated with cognitive function, regardless of white matter atrophy and white matter lesion volume. This suggests that measuring white matter integrity has added value beyond macrostructural assessment of white matter changes to study the relation between white matter and cognition.

MR fetography using heavily T2-weighted sequences: Comparison of thin- and thick-slab acquisitions

Purpose To evaluate the use of MR-fetography sequences in identifying the major fetal structures and to compare thick- and thin-slab acquisitions for their diagnostic value. Materials and methods Twenty-one consecutive, pregnant women with suspected fetal pathology underwent fetal magnetic resonance imaging (MRI) using a 1.5 T MRI unit. Heavily T2-weighted, single-shot fast spin-echo (SSFSE) sequences with a long echo train (MR-fetography) were acquired in a thick- and thin-slab modus. Thick- and thin-slab acquisitions were reviewed by two experienced radiologists with regard to the overall image quality and landmark anatomical structures (spinal canal, spinal cord, posterior fossa, cerebellum, brainstem, basal cisterns, stomach, urinary bladder and umbilical cord according to a three-scale grading system (good, moderate and poor). Visibility scores were calculated and compared between both sequences. Results Overall image quality was graded good in 76.2%, moderate in 19.0% and poor in 4.8% for thick-slab images and good in 81%, moderate in 14.3% and poor in 4.8% for thin-slab images. The visibility scores of the thick/thin-slab images for evaluation of the main fetal structures were as follows: for the spinal canal 2.8 ± 0.4/2.9 ± 0.54 ( p > 0.05), spinal cord 2.4 ± 0.75/2.7 ± 0.66 ( p > 0.05), posterior fossa components (cerebellum, brainstem and basal cisterns) 2.4 ± 0.68/2.8 ± 0.54; 2.4 ± 0.67/2.7 ± 0.66; 2.5 ± 0.51/2.7 ± 0.56 ( p < 0.05), stomach 2.8 ± 0.44/2.9 ± 0.48 ( p > 0.05), urinary bladder 2.8 ± 0.51/2.8 ± 0.54 ( p > 0.05) and umbilical cord 2.9 ± 0.30/2.6 ± 0.60 ( p < 0.05). Conclusion Heavily T2-weighted MR-fetography renders a quick overview of fetal contours, fetal position, amount of amniotic fluid and integrity and presence of several major fluid containing structures. Thick- and thin-slab acquisitions render complementary information. Thick-slab images display the entire fetus in one projection while thin-slab images provide more detailed anatomical information. The short imaging time usually allows measuring both thick- and thin-slab images. MR-fetography is as a helpful addition to conventional fetal MRI. MR-fetography should not be viewed as a single, stand alone sequence but as a supporting fast MR sequence in a well-designed multisequence fetal MRI protocol. Future studies evaluating larger patient groups are mandatory.

Does high field MRI allow an earlier diagnosis of multiple sclerosis?

High field magnetic resonance imaging (MRI) provides higher lesion load measurements in patients presenting with clinically isolated syndromes (CIS) suggestive of demyelination and has impact upon the classification of these syndromes and potentially, the diagnosis of multiple sclerosis (MS). To investigate whether high field MRI can provide an earlier diagnosis of definite MS within the International Panel (IP) and Swanton criteria. Forty patients presenting with CIS suggestive of MS were included. All patients received multi-sequence MRI at 1.5 Tesla (T) and 3T as well as a neurological assessment at baseline. Follow-up visits including MRI at both field strengths and neurological examinations were scheduled 3-4 and 6-7 months after the first clinical event. Based on MRI and clinical findings, fulfilled IP criteria as well as Swanton criteria were analysed. At baseline, the higher detection rate of inflammatory lesions using high field MRI leads to higher classifications according to the Swanton criteria in 15 % of the patients. One additional patient was diagnosed with dissemination in space according to Swanton and IP criteria. During follow-up, an earlier diagnosis of definite MS could not be accomplished, neither according to the IP nor to the Swanton criteria. Although high field MRI shows a higher detection rate of inflammatory brain lesion in CIS and MS patients with an influence according to MRI criteria, this influence does not lead to an earlier diagnosis of lesion dissemination in time and therefore definite MS.

Correlation of Carotid Atheromatous Plaque Inflammation Using USPIO-Enhanced MR Imaging With Degree of Luminal Stenosis

Inflammation is a recognized risk factor for the vulnerable atherosclerotic plaque. The study explores the relationship between the degree of Magnetic Resonance (MR)-defined inflammation using Ultra Small Super-Paramagnetic Iron Oxide (USPIO) particles and the severity of luminal stenosis in asymptomatic carotid plaques. Seventy-one patients with an asymptomatic carotid stenosis of > or = 40% underwent multi-sequence USPIO-enhanced MR imaging. Stenosis severity was measured according to the NASCET and ECST methods. No demonstrable relationship between inflammation as measured by USPIO-enhanced signal change and the degree of luminal stenosis was found. Inflammation and stenosis are likely to be independent risk factors, although this needs to be further validated.