MR Research Laboratory

Rochester, MN, United States

MR Research Laboratory

Rochester, MN, United States

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Bergsland N.,MR Research Laboratory | Bergsland N.,State University of New York at Buffalo | Bergsland N.,Polytechnic of Milan | Lagana M.M.,MR Research Laboratory | And 6 more authors.
Multiple Sclerosis | Year: 2015

Background: The relationship between white matter injury and cortical atrophy development in relapsing-remitting multiple sclerosis (RRMS) remains unclear. Objectives: To investigate the associations between corticospinal tract integrity and cortical morphology measures of the primary motor cortex in RRMS patients and healthy controls. Methods: 51 RRMS patients and 30 healthy controls underwent MRI examination for cortical reconstruction and assessment of corticospinal tract integrity. Partial correlation and multiple linear regression analyses were used to investigate the associations of focal and normal appearing white matter (NAWM) injury of the corticospinal tract with thickness and surface area measures of the primary motor cortex. Relationships between MRI measures and clinical disability as assessed by the Expanded Disability Status Scale and disease duration were also investigated. Results: In patients only, decreased cortical thickness was related to increased corticospinal tract NAWM mean, axial and radial diffusivities in addition to corticospinal tract lesion volume. The final multiple linear regression model for PMC thickness retained only NAWM axial diffusivity as a significant predictor (adjusted R2= 0.270, p= 0.001). Clinical measures were associated with NAWM corticospinal tract integrity measures. Conclusions: Primary motor cortex thinning in RRMS is related to alterations in connected white matter and is best explained by decreased NAWM integrity. © 2015 The Author(s).


Tavazzi E.,Scientific Institute Santa Maria Nascente | Lagana M.M.,MR Research Laboratory | Bergsland N.,MR Research Laboratory | Bergsland N.,Polytechnic of Milan | And 6 more authors.
Neurological Sciences | Year: 2015

Primary progressive multiple sclerosis (PPMS) and amyotrophic lateral sclerosis (ALS) seem to share some clinical and pathological features. MRI studies revealed the presence of grey matter (GM) atrophy in both diseases, but no comparative data are available. The objective was to compare the regional patterns of GM tissue loss in PPMS and ALS with voxel-based morphometry (VBM). Eighteen PPMS patients, 20 ALS patients, and 31 healthy controls (HC) were studied with a 1.5 Tesla scanner. VBM was performed to assess volumetric GM differences with age and sex as covariates. Threshold-free cluster enhancement analysis was used to obtain significant clusters. Group comparisons were tested with family-wise error correction for multiple comparisons (p < 0.05) except for HC versus MND which was tested at a level of p < 0.001 uncorrected and a cluster threshold of 20 contiguous voxels. Compared to HC, ALS patients showed GM tissue reduction in selected frontal and temporal areas, while PPMS patients showed a widespread bilateral GM volume decrease, involving both deep and cortical regions. Compared to ALS, PPMS patients showed tissue volume reductions in both deep and cortical GM areas. This preliminary study confirms that PPMS is characterized by a more diffuse cortical and subcortical GM atrophy than ALS and that, in the latter condition, brain damage is present outside the motor system. These results suggest that PPMS and ALS may share pathological features leading to GM tissue loss. © 2014, Springer-Verlag Italia.


PubMed | MR Research Laboratory, Polytechnic of Milan and Multiple Sclerosis Center
Type: Journal Article | Journal: Multiple sclerosis (Houndmills, Basingstoke, England) | Year: 2015

The relationship between white matter injury and cortical atrophy development in relapsing-remitting multiple sclerosis (RRMS) remains unclear.To investigate the associations between corticospinal tract integrity and cortical morphology measures of the primary motor cortex in RRMS patients and healthy controls.51 RRMS patients and 30 healthy controls underwent MRI examination for cortical reconstruction and assessment of corticospinal tract integrity. Partial correlation and multiple linear regression analyses were used to investigate the associations of focal and normal appearing white matter (NAWM) injury of the corticospinal tract with thickness and surface area measures of the primary motor cortex. Relationships between MRI measures and clinical disability as assessed by the Expanded Disability Status Scale and disease duration were also investigated.In patients only, decreased cortical thickness was related to increased corticospinal tract NAWM mean, axial and radial diffusivities in addition to corticospinal tract lesion volume. The final multiple linear regression model for PMC thickness retained only NAWM axial diffusivity as a significant predictor (adjusted R(2)= 0.270, p= 0.001). Clinical measures were associated with NAWM corticospinal tract integrity measures.Primary motor cortex thinning in RRMS is related to alterations in connected white matter and is best explained by decreased NAWM integrity.


PubMed | MR Research Laboratory, Polytechnic of Milan, State University of New York at Buffalo and Multiple Sclerosis Center
Type: Journal Article | Journal: Journal of neuroimaging : official journal of the American Society of Neuroimaging | Year: 2016

With respect to healthy controls (HCs), increased iron concentrations in the deep gray matter (GM) and decreased white matter (WM) integrity are common findings in multiple sclerosis (MS) patients. The association between these features of the disease remains poorly understood. We investigated the relationship between deep iron deposition in the deep GM and WM injury in associated fiber tracts in MS patients.Sixty-six MS patients (mean age 50.0 years, median Expanded Disability Status Scale 5.25, mean disease duration 19.1 years) and 29 HCs, group matched for age and sex were imaged on a 1.5T scanner. Susceptibility-weighted imaging and diffusion tensor imaging (DTI) were used for assessing high-pass filtered phase values in the deep GM and normal appearing WM (NAWM) integrity in associated fiber tracts, respectively. Correlation analyses investigated the associations between filtered phase values (suggestive of iron content) and WM damage.Areas indicative of increased iron levels were found in the left and right caudates as well as in the left thalamus. MS patients presented with decreased DTI-derived measures of tissue integrity in the associated WM tracts. Greater mean, axial and radial diffusivities were associated with increased iron levels in all three GM areas (r values .393 to .514 with corresponding P values .003 to <.0001). Global NAWM diffusivity measures were not related to mean filtered phase values within the deep GM.Increased iron concentration in the deep GM is associated with decreased tissue integrity of the connected WM in MS patients.


Riederer S.J.,MR Research Laboratory | Johnson C.P.,University of Iowa | Weavers P.T.,MR Research Laboratory
13th IEEE International Conference on BioInformatics and BioEngineering, IEEE BIBE 2013 | Year: 2013

Accurate, fast, sensitive, and safe imaging of the cardiovascular system has major societal benefits owing to the high prevalence of cardiovascular disease. This is particularly challenging in imaging the peripheral vasculature, defined as extending from the renal artery origins to the ankles, because of the long (>120 cm) superior-inferior (S/I) field of view. Contrast-enhanced MR angiography provides major advantages compared to other imaging methods because it uses no ionizing radiation, provides 3D images, and requires only a relatively benign intravenous injection of contrast material. However, such imaging has major technical challenges in that the speed of passage of the contrast-enhanced blood through the vasculature is highly variable from patient to patient and the potentially rapid enhancement of veins can interfere with the radiological interpretation of disease in the companion arteries. The purpose of this work is to describe MRI physics and engineering methods designed to rapidly acquire high spatial resolution images of the peripheral vasculature at individual table positions or "stations," and then to integrate these methods with real-time signal processing to allow interactive control of the MRI patient table, allowing it to advance in synchrony with the advancing contrast on a patient-specific basis. Results are presented with single station techniques to illustrate the potential image performance as well as in the more demanding and desired multi-station application in which the time available for data acquisition is limited at each station. © 2013 IEEE.


Johnson C.P.,University of Iowa | Weavers P.T.,MR Research Laboratory | Borisch E.A.,MR Research Laboratory | Grimm R.C.,MR Research Laboratory | And 6 more authors.
Radiology | Year: 2014

Purpose: To determine the feasibility of using real-time fluoroscopic tracking for bolus-chase magnetic resonance (MR) angiography of peripheral vasculature to image three stations from the aortoiliac bifurcation to the pedal arteries. Materials and Methods: This prospective study was institutional review board approved and HIPAA compliant. Eight healthy volunteers (three men; mean age, 48 years; age range, 30-81 years) and 13 patients suspected of having peripheral arterial disease (five men; mean age, 67 years; age range, 47-81 years) were enrolled and provided informed consent. All subjects were imaged with the fluoroscopic tracking MR angiographic protocol. Ten patients also underwent a clinical computed tomographic (CT) angiographic runoff examination. Two readers scored the MR angiographic studies for vessel signal intensity and sharpness and presence of confounding artifacts and venous contamination at 35 arterial segments. Mean aggregate scores were assessed. The paired MR angiographic and CT angiographic studies also were scored for visualization of disease, reader confidence, and overall diagnostic quality and were compared by using a Wilcoxon signed rank test. Results: Real-time fluoroscopic tracking performed well technically in all studies. Vessel segments were scored good to excellent in all but the following categories: For vessel signal intensity and sharpness, the abdominal aorta, iliac arteries, distal plantar arteries, and plantar arch were scored as fair to good; and for presence of confounding artifacts, the abdominal aorta and iliac arteries were scored as fair. The MR angiograms and CT angiograms did not differ significantly in any scoring category (reader 1: P = .50, .39, and .39; reader 2: P = .41, .61, and .33, respectively). CT scores were substantially better in 20% (four of 20) and 25% (five of 20) of the pooled evaluations for the visualization of disease and overall image quality categories, respectively, versus 5% (one of 20) for MR scores in both categories. Conclusion: Three-station bolus-chase MR angiography with real-time fluoroscopic tracking provided high-spatial-resolution arteriograms of the peripheral vasculature, enabled precise triggering of table motion, and compared well with CT angiograms. © RSNA, 2014.


PubMed | MR Research Laboratory, National Research Council Italy, Unita Operativa di Sclerosi Multipla, Unita Operativa di Neuroradiologia and University of Ferrara
Type: | Journal: BMC medical imaging | Year: 2016

Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) abnormalities in patients with multiple sclerosis (MS) are currently measured by a complex combination of separate procedures. Therefore, the purpose of this study was to provide a reliable method for reducing analysis complexity and obtaining reproducible results.We implemented a semi-automated measuring system in which different well-known software components for magnetic resonance imaging (MRI) analysis are integrated to obtain reliable measurements of DWI and PWI disturbances in MS.We generated the Diffusion/Perfusion Project (DPP) Suite, in which a series of external software programs are managed and harmonically and hierarchically incorporated by in-house developed Matlab software to perform the following processes: 1) image pre-processing, including imaging data anonymization and conversion from DICOM to Nifti format; 2) co-registration of 2D and 3D non-enhanced and Gd-enhanced T1-weighted images in fluid-attenuated inversion recovery (FLAIR) space; 3) lesion segmentation and classification, in which FLAIR lesions are at first segmented and then categorized according to their presumed evolution; 4) co-registration of segmented FLAIR lesion in T1 space to obtain the FLAIR lesion mask in the T1 space; 5) normal appearing tissue segmentation, in which T1 lesion mask is used to segment basal ganglia/thalami, normal appearing grey matter (NAGM) and normal appearing white matter (NAWM); 6) DWI and PWI map generation; 7) co-registration of basal ganglia/thalami, NAGM, NAWM, DWI and PWI maps in previously segmented FLAIR space; 8) data analysis. All these steps are automatic, except for lesion segmentation and classification.We developed a promising method to limit misclassifications and user errors, providing clinical researchers with a practical and reproducible tool to measure DWI and PWI changes in MS.


Weavers P.T.,MR Research Laboratory | Borisch E.A.,MR Research Laboratory | Riederer S.J.,MR Research Laboratory
Magnetic Resonance in Medicine | Year: 2015

Purpose To develop and validate a method for choosing the optimal two-dimensional CAIPIRINHA kernel for subtraction contrast-enhanced MR angiography (CE-MRA) and estimate the degree of image quality improvement versus that of some reference acceleration parameter set at R ≥ 8. Methods A metric based on patient-specific coil calibration information was defined for evaluating optimality of CAIPIRINHA kernels as applied to subtraction CE-MRA. Evaluation in retrospective studies using archived coil calibration data from abdomen, calf, foot, and hand CE-MRA exams was accomplished with an evaluation metric comparing the geometry factor (g-factor) histograms. Prospective calf, foot, and hand CE-MRA studies were evaluated with vessel signal-to-noise ratio (SNR). Results Retrospective studies show g-factor improvement for the selected CAIPIRINHA kernels was significant in the feet, moderate in the abdomen, and modest in the calves and hands. Prospective CE-MRA studies using optimal CAIPIRINHA show reduced noise amplification with identical acquisition time in studies of the feet, with minor improvements in the hands and calves. Conclusion A method for selection of the optimal CAIPIRINHA kernel for high (R ≥ 8) acceleration CE-MRA exams given a specific patient and receiver array was demonstrated. CAIPIRINHA optimization appears valuable in accelerated CE-MRA of the feet and to a lesser extent in the abdomen. Magn Reson Med 73:2234-2242, 2015. © 2014 Wiley Periodicals, Inc.


Johnson C.P.,MR Research Laboratory | Polley T.W.,MR Research Laboratory | Glockner J.F.,MR Research Laboratory | Young P.M.,MR Research Laboratory | Riederer S.J.,MR Research Laboratory
Magnetic Resonance in Medicine | Year: 2013

Time-resolved three-dimensional contrast-enhanced MR angiography often relies on view sharing of peripheral k-space data to enable acquisition of angiograms with both high spatial resolution and a rapid frame rate. It is typically assumed that k-space will be fully sampled during passage of the contrast bolus arterial phase. However, this is not the case when view sharing is incomplete, for example, at the leading edge of an enhancing vessel or if acquisition time is limited as in fluoroscopic tracking for multistation bolus chase MR angiography. Incomplete view sharing will degrade image quality, for example, by reducing vessel signal and sharpness and increasing undersampling artifacts. In this work, the evolution of angiogram quality with view sharing is quantitatively assessed in phantom experiments and in vivo contrast-enhanced MR angiography calf studies. It is demonstrated that there are multiple sets of sequence parameters that can yield a target image update time, but the choice of parameters can profoundly affect how image quality evolves with view sharing. A fundamental tradeoff between vessel signal and sharpness and its relationship to the sequence temporal footprint is investigated and discussed. © 2012 Wiley Periodicals, Inc.


Johnson C.P.,MR Research Laboratory | Borisch E.A.,MR Research Laboratory | Glockner J.F.,MR Research Laboratory | Young P.M.,MR Research Laboratory | Riederer S.J.,MR Research Laboratory
Journal of Magnetic Resonance Imaging | Year: 2012

Purpose: To refine, adapt, and evaluate the technical aspects of fluoroscopic tracking for generating dual-station high-spatial-resolution MR angiograms of the calves and feet using a single injection of contrast material. Materials and Methods: Nine subjects (seven healthy volunteers followed by two patients) were imaged using a two-station calf-foot three-dimensional time-resolved bolus chase MR angiography protocol which provided <1.0 mm 3 spatial resolution throughout and 2.5- and 6.6-s frame times at the calf and foot stations, respectively. Real-time reconstruction of calf station time frames allowed visually guided triggering of table advance to the foot station. The studies were independently read and scored by two radiologists in six image quality categories. Results: On average, overall diagnostic quality at the calf and foot stations was good-to-excellent, the calf arteries and all but the smallest foot arteries had good-to-excellent signal and sharpness, artifact and venous contamination were minor, and signal continuity across the inter-station interface was good. Conclusion: The feasibility of fluoroscopic tracking has been demonstrated as an efficient approach for high spatiotemporal imaging of the arteries of the calves and feet with good-to-excellent diagnostic quality and low degrading venous contamination. © 2012 Wiley Periodicals, Inc.

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