Postmortem Magnetic Resonance Imaging Study Research Articles

Lesion size and shape in central vein sign assessment for multiple sclerosis diagnosis: An in vivo and postmortem MRI study

Background: The “central vein sign” (CVS), a linear hypointensity on T2*-weighted imaging corresponding to a central vein/venule, is associated with multiple sclerosis (MS) lesions. The effect of lesion-size exclusion criteria on MS diagnostic accuracy has not been extensively studied. Objective: Investigate the optimal lesion-size exclusion criteria for CVS use in MS diagnosis. Methods: Cross-sectional study of 163 MS and 51 non-MS, and radiological/histopathological correlation of 5 MS and 1 control autopsy cases. The effects of lesion-size exclusion on MS diagnosis using the CVS, and intralesional vein detection on histopathology were evaluated. Results: CVS+ lesions were larger compared to CVS− lesions, with effect modification by MS diagnosis (mean difference +7.7 mm3, p = 0.004). CVS percentage-based criteria with no lesion-size exclusion showed the highest diagnostic accuracy in differentiating MS cases. However, a simple count of three or more CVS+ lesions greater than 3.5 mm is highly accurate and can be rapidly implemented (sensitivity 93%; specificity 88%). On magnetic resonance imaging (MRI)-histopathological correlation, the CVS had high specificity for identifying intralesional veins (0/7 false positives). Conclusion: Lesion-size measures add important information when using CVS+ lesion counts for MS diagnosis. The CVS is a specific biomarker corresponding to intralesional veins on histopathology.

Normal development of costal element ossification centers of sacral vertebrae in the fetal spine: a postmortem magnetic resonance imaging study.

This postmortem magnetic resonance imaging (MRI) study of the fetal spine aimed to describe the timing of appearance, shape, volume, and relative positions of the S1-S3 costal element ossification centers (CEOCs). We obtained sagittal 3D dual-echo steady-state with water excitation T2 images of the entire spine in 71 fetuses (gestational ages (GAs), 17-42weeks). Computed tomography and histological examinations were performed on two fetal specimens (GAs, 21 and 30weeks) to validate the MR images. The presence/absence of each sacral CEOC was recorded according to the GA. CEOC volume was measured. We analyzed the CEOC position relative to the vertebral column and ilium. The S1, S2, andS3 CEOCs first appeared at 23, 22, and 29weeks, respectively. The S1 and S2 CEOCs could be detected in all fetuses with GAs of ≥ 30weeks and ≥ 35weeks, respectively, while the S3 CEOCs were variably present until term. The percentages of detection of the S1 and S2 CEOCs were significantly greater than that of the S3 CEOCs at each GA. At S1 and S2, the CEOC volume increased exponentially with GA. The relative positions of the S1 and S2 CEOCs, but not the S3 CEOCs, significantly correlated with GA (P < 0.001). We have described the timeline of appearance as well as the volume and position of the S1-S3 CEOCs in the fetal spine on postmortem MRI according to GA.

Comparison of iron deposition in subcortical structures of brains with Parkinsonian syndromes: A post-mortem 7.0-tesla magnetic resonance study

It is not known whether iron (Fe) accumulation is a secondary event in the cascade of the neuronal degeneration rather than the primary cause in different Parkinsonian diseases. The purpose of the present post-mortem study is to evaluate and compare the Fe content in brains of different parkinsonian syndromes with normal control brains. Twenty-six normal brains were compared to 7 with idiopathic Parkinson’s disease (PD), 18 with progressive supranuclear palsy (PSP), 18 with Lewy body dementia (LBD), 6 with corticobasal degeneration (CBD) and 5 with multiple system atrophy (MSA). The hippocampus and 11 subcortical structures were submitted to a 7.0-tesla magnetic resonance imaging (MRI). T2 and T2* sequences were performed: the degree of T2* hypo-intensity, representing the degree of Fe content in the different brain regions, was determined semi-quantitatively. No significant differences in Fe content were observed in all examined structures between normal brains and those with PD, PSP, LBD and CBD. In MSA there was a selective hypo-intensity on T2* sequence in the putamen, reflecting Fe increase, with on the other hand a significant Fe decrease at the level of the dentate nucleus of the cerebellum. The present post-mortem MRI study confirms that the increased hypo-intensity in the putamen is a diagnostic hallmark of MSA, but that also the low Fe content at the level of the dentate nucleus has also to be considered as a valuable indicator of this disease.

Normal development of sacrococcygeal centrum ossification centers in the fetal spine: a postmortem magnetic resonance imaging study

To describe the temporal pattern of the appearance of the S1-Co1 centrum ossification centers (COCs) and provide reference data for the S1-S5 COCs and sacral length at various gestational ages (GAs). Postmortem magnetic resonance imaging (MRI) was performed on 71 fetuses (GA, 17-42weeks) using the 3D dual-echo steady-state with water excitation T2 sequence in the sagittal plane. To confirm the reliability of this sequence, the MRI data were compared with the CT and histologic data obtained from two fetuses (GAs, 21 and 30weeks). The presence or absence of each sacrococcygeal COC was recorded. Sacral length and S1-S5 COC height, sagittal diameter, transverse diameter, cross-sectional area, and volume were measured. All fetuses showed S1-S3 COCs by 17weeks, S4 COCs by 19weeks, and S5 COCs by 28weeks. The S4, S5, and Co-1 COCs were visualized in 70 (98.59%), 51 (71.83%), and 21 (29.58%) fetuses, respectively. Sacral length, height, sagittal, and transverse diameters increased linearly, while cross-sectional area and volume increased exponentially with advancing GA. Mean growth rates of the sagittal and transverse diameters, cross-sectional area, and volume, but not of height, significantly differed among the S1-S5 vertebrae. We have presented the timing of appearance of individual sacrococcygeal COCs and the age-specific, normative MRI reference values for sacral length and the morphometric parameters of the sacral COCs, which are of clinical importance in the diagnosis of congenital sacral abnormalities and skeletal dysplasia.

Comparison of Premortem Magnetic Resonance Imaging and Postmortem Autopsy Findings of a Cortical Microinfarct

An 85-year-old woman diagnosed with amyotrophic lateral sclerosis died of pneumonia and was autopsied. Magnetic resonance imaging (MRI) performed 16 days before death revealed an intracortical high-intensity lesion in her right temporal cortex on three-dimensional (3D)-double inversion recovery (DIR) and 3D-fluid-attenuated inversion recovery (FLAIR) images. Histopathological examination indicated a cortical microinfarct (CMI) juxtaposed to cerebral amyloid angiopathy. Recently, in vivo detection of CMIs using 3D-DIR and 3D-FLAIR on 3-tesla MRI has been reported, and postmortem MRI study confirmed the presence of CMIs. This is the first case study to compare CMI findings detected upon premortem MRI to the CMI itself discovered upon postmortem neuropathological examination.

Frequency and topography of small cerebrovascular lesions in vascular and in mixed dementia: a post-mortem 7-tesla magnetic resonance imaging study with neuropathological correlates.

<i><b>Introduction</b>: Mixed dementia (MixD) refers to a combination of definite Alzheimer's disease (AD) and vascular encephalopathy. The existence of a "pure" type of vascular dementia (VaD) is controversial. There is a need to find magnetic resonance imaging (MRI) characteristics allowing the distinction between VaD and MixD. The present post-mortem 7.0-tesla MRI compares the frequency or severity and the topography of the small cerebrovascular lesions in brains of patients with VaD and with MixD. <b>Material and methods</b>: Based on neuropathological criteria, 14 brains were classified as VaD, 24 as MixD and 11 as controls. Three coronal sections of a cerebral hemisphere and a horizontal section of a cerebellar hemisphere underwent T2 and T2* 7.0-tesla MRI examination. The mean values and topographic distribution of white matter changes (WMCs), lacunar infarcts (LIs), cortical microbleeds (CoMBs) and cortical microinfarcts (CoMIs) were determined and compared between the different groups. <b>Results</b>: Compared to the controls, both VaD and MixD brains had significantly more severe WMCs and increased numbers of CoMBs and CoMIs. Lacunar infarcts predominated only in the VaD cases. On mutual comparison of VaD and MixD brains, CoMBs and CoMIs predominated in the frontal lobe and the cerebellum of VaD, while were mainly present in the occipital lobe of MixD. White matter changes predominated in the temporal lobe of MixD cases. Lacunar infarcts were significantly increased in the corona radiata and putamen of VaD patients. <b>Conclusions</b>: The present post-mortem MRI study shows clear differences in the distribution and the types of cerebrovascular lesions on high-field MRI, confirming that VaD and MixD are different diseases. </i>.

Chronic Multiple Sclerosis Lesions: Characterization with High-Field-Strength MR Imaging

To elucidate the mechanism of magnetic resonance (MR) imaging contrast in multiple sclerosis (MS) lesion appearance by using susceptibility-weighted imaging and to assess with histologic correlation the role of iron and myelin in generating this MR imaging contrast. Each patient provided written consent to a human subject protocol approved by an institutional review board. High-spatial-resolution susceptibility-weighted 7.0-T MR images were obtained in 21 patients with MS. Contrast patterns in quantitative phase and R2* images, derived from 7.0-T data, were investigated in 220 areas defined as chronic MS lesions on conventional T2-weighted fluid-attenuated inversion recovery, T2-weighted, and T1-weighted spin-echo images. The presence of positive or negative phase shifts (ie, decreased or increased MR frequency, respectively) was assessed in each lesion. In addition, postmortem MR imaging was performed at 7.0 T and 11.7 T, and its results were correlated with those of immunohistochemical staining specific for myelin, iron, and ferritin. The majority (133 [60.5%] of 220) of the identified lesions had a normal phase and reduced R2*. A substantial fraction of the lesions (84 [38.2%] of 220) had negative phase shift, either uniformly or at their rim, and a variety of appearances on R2* maps. These two lesion contrast patterns were reproduced in the postmortem MR imaging study. Comparison with histologic findings showed that, while R2* reduction corresponded to severe loss of both iron and myelin, negative phase shift corresponded to focal iron deposits with myelin loss. Combined analysis of 7.0-T R2* and phase data may help in characterizing the pathologic features of MS lesions. The observed R2* decreases suggest profound myelin loss, whereas negative phase shifts suggest a focal iron accumulation.

Development of laminar organization of the fetal cerebrum at 3.0T and 7.0T: a postmortem MRI study

The purpose of this study is to show the condition of laminar organization on 3.0T and 7.0T postmortem magnetic resonance imaging (MRI) and analyze developmental changes. Heads of 131 fetal specimens of 14-40 weeks gestational age (GA) were scanned by 3.0T MRI. Eleven fetal specimens of 14-27 weeks GA were scanned by 7.0T MRI. Clear images were chosen for analysis. On T₁-weighted 3.0T MRI, layers could be visualized at 14 weeks GA and appeared clearer after 18 weeks GA. On 7.0T MRI, four zones could be recognized at 14 weeks GA. During 15-22 weeks GA, when laminar organization appeared typical, seven layers including the periventricular zone and external capsule fibers could be differentiated, which corresponded to seven zones in histological stained sections. At 23-28 weeks GA, laminar organization appeared less typical, and borderlines among them appeared obscured. After 30 weeks GA, it disappeared and turned into mature-like structures. The developing lamination appeared the most distinguishable at the parieto-occipital part of brain and peripheral regions of the hippocampus. The migrating thalamocortical afferents were probably delineated as a high signal layer located at the lower, middle, and upper part of the subplate zone at 16-28 weeks GA on T₁-weighted 3.0T MRI. T₁-weighted 3.0T MRI and T₂-weighted 7.0T MRI can well demonstrate the laminar organization. Development of the lamination follows a specific spatio-temporal regularity, and postmortem MRI of the parieto-occipital part of brain obtained with 3.0T or 7.0T is an effective way to show developmental changes.

A pilot study of human brain tissue post-magnetic resonance imaging: Information from the National Deep Brain Stimulation Brain Tissue Network (DBS-BTN)

Introduction The safety of magnetic resonance imaging (MRI) for deep brain stimulation (DBS) patients is of great importance to both movement disorders clinicians and to radiologists. The present study utilized the Deep Brain Stimulation Brain Tissue Network's (DBS-BTN's) clinical and neuropathological database to search for evidence of adverse effects of MRI performed on implanted DBS patients. Hypothesis Performing a 1.5 T MRI with a head receive coil on patients with implanted DBS devices should not result in evidence of adverse clinical or pathological effects in the DBS-BTN cohort. Further, exposing post-mortem DBS-BTN brains with DBS leads to extended 3 T MRI imaging should not result in pathological adverse effects. Methods An electronic literature search was performed to establish clinical and neuropathological criteria for evidence of MRI-related adverse reactions in DBS patients. A retrospective chart review of the DBS-BTN patients was then performed to uncover potential adverse events resulting from MRI scanning. DBS patient characteristics and MRI parameters were recorded for each patient. In addition, 3 T MRI scans were performed on 4 post-mortem brains with DBS leads but without batteries attached. Detailed neuropathological studies were undertaken to search for evidence of MRI-induced adverse tissue changes. Results No clinical signs or symptoms or MRI-induced adverse effects were discovered in the DBS-BTN database, and on detailed review of neuroimaging studies. Neuropathological examination did not reveal changes consistent with MRI-induced heating damage. The novel study of four brains with prolonged 3 T post-mortem magnetic field exposure (DBS leads left in place) also did not reveal pathological changes consistent with heat related damage. Discussion The current study adds important information to the data on the safety of MRI in DBS patients. Novel post-mortem MRI studies provide additional information regarding the safety of 3 T MRI in DBS patients, and could justify additional studies especially post-mortem scans with battery sources in place. Conclusion The lack of pathological findings in the DBS-BTN database and the lack of tissue related changes following prolonged exposure to 3 T MRI in the post-mortem brains suggest that MRI scanning in DBS patients may be relatively safe, especially under current guidelines requiring a head receive coil. Subsequent studies exploring the safety of 1.5 T versus 3 T MRI in DBS patients should utilize more in depth post-mortem imaging to better simulate the human condition.