36 research outputs found
High-resolution DCE-MRI of the pituitary gland using radial k-space acquisition with compressed sensing reconstruction
BACKGROUND AND PURPOSE: The pituitary gland is located outside of the blood-brain barrier. Dynamic T1 weighted contrast enhanced sequence is considered to be the gold standard to evaluate this region. However, it does not allow assessment of intrinsic permeability properties of the gland. Our aim was to demonstrate the utility of radial volumetric interpolated brain examination with the golden-angle radial sparse parallel technique to evaluate permeability characteristics of the individual components (anterior and posterior gland and the median eminence) of the pituitary gland and areas of differential enhancement and to optimize the study acquisition time.
MATERIALS AND METHODS: A retrospective study was performed in 52 patients (group 1, 25 patients with normal pituitary glands; and group 2, 27 patients with a known diagnosis of microadenoma). Radial volumetric interpolated brain examination sequences with goldenangle radial sparse parallel technique were evaluated with an ROI-based method to obtain signal-time curves and permeability measures of individual normal structures within the pituitary gland and areas of differential enhancement. Statistical analyses were performed to assess differences in the permeability parameters of these individual regions and optimize the study acquisition time.
RESULTS: Signal-time curves from the posterior pituitary gland and median eminence demonstrated a faster wash-in and time of
maximum enhancement with a lower peak of enhancement compared with the anterior pituitary gland (P .005). Time-optimization
analysis demonstrated that 120 seconds is ideal for dynamic pituitary gland evaluation. In the absence of a clinical history, differences in the signal-time curves allow easy distinction between a simple cyst and a microadenoma.
CONCLUSIONS: This retrospective study confirms the ability of the golden-angle radial sparse parallel technique to evaluate the
permeability characteristics of the pituitary gland and establishes 120 seconds as the ideal acquisition time for dynamic pituitary gland
imaging
Normal age-related signal change in the laryngeal cartilages
MRI may be used for detecting cartilage invasion in patients with laryngeal carcinoma. However, the normal laryngeal ossification pattern has not been studied. Our purpose was to examine the normal age-related signal patterns in the cricoid, thyroid and arytenoid cartilages on T1-weighted images. Signal in the cartilages was assessed by two radiologists in a blinded fashion using three-point scales for intensity and symmetry. Statistical analysis consisted of logistic and monotonic regression. There was excellent interobserver agreement (>85%) for all categories. The cartilages predominantly ossify symmetrically and the extent of high signal from all three increases with age. The latter may help in detection of cartilage invasion by tumor in older patients. Normal symmetry may be helpful when comparing sides for tumor invasion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46665/1/234_2003_Article_1153.pd
A comparative study of cranial, blunt trauma fractures as seen at medicolegal autopsy and by Computed Tomography
<p>Abstract</p> <p>Background</p> <p>Computed Tomography (CT) has become a widely used supplement to medico legal autopsies at several forensic institutes. Amongst other things, it has proven to be very valuable in visualising fractures of the cranium. Also CT scan data are being used to create head models for biomechanical trauma analysis by Finite Element Analysis. If CT scan data are to be used for creating individual head models for retrograde trauma analysis in the future we need to ascertain how well cranial fractures are captured by CT scan. The purpose of this study was to compare the diagnostic agreement between CT and autopsy regarding cranial fractures and especially the precision with which cranial fractures are recorded.</p> <p>Methods</p> <p>The autopsy fracture diagnosis was compared to the diagnosis of two CT readings (reconstructed with Multiplanar and Maximum Intensity Projection reconstructions) by registering the fractures on schematic drawings. The extent of the fractures was quantified by merging 3-dimensional datasets from both the autopsy as input by 3D digitizer tracing and CT scan.</p> <p>Results</p> <p>The results showed a good diagnostic agreement regarding fractures localised in the posterior fossa, while the fracture diagnosis in the medial and anterior fossa was difficult at the first CT scan reading. The fracture diagnosis improved during the second CT scan reading. Thus using two different CT reconstructions improved diagnosis in the medial fossa and at the impact points in the cranial vault. However, fracture diagnosis in the anterior and medial fossa and of hairline fractures in general still remained difficult.</p> <p>Conclusion</p> <p>The study showed that the forensically important fracture systems to a large extent were diagnosed on CT images using Multiplanar and Maximum Intensity Projection reconstructions. Difficulties remained in the minute diagnosis of hairline fractures. These inconsistencies need to be resolved in order to use CT scan data of victims for individual head modelling and trauma analysis.</p
Pseudoprogression, radionecrosis, inflammation or true tumor progression? challenges associated with glioblastoma response assessment in an evolving therapeutic landscape
The wide variety of treatment options that exist for glioblastoma, including surgery, ionizing radiation, anti-neoplastic chemotherapies, anti-angiogenic therapies, and active or passive immunotherapies, all may alter aspects of vascular permeability within the tumor and/or normal parenchyma. These alterations manifest as changes in the degree of contrast enhancement or T2-weighted signal hyperintensity on standard anatomic MRI scans, posing a potential challenge for accurate radiographic response assessment for identifying anti-tumor effects. The current review highlights the challenges that remain in differentiating true disease progression from changes due to radiation therapy, including pseudoprogression and radionecrosis, as well as immune or inflammatory changes that may occur as either an undesired result of cytotoxic therapy or as a desired consequence of immunotherapies
Correlation between Leukoaraiosis Volume and Circle of Willis Variants
BACKGROUND AND PURPOSE:
The Circle of Willis (COW) is the main collateral system between the bilateral carotid systems and the posterior circulation. COW normal variants are encountered in up to 62% of subjects. We hypothesize that, in patients with carotid artery stenosis, the presence of COW variants is a risk factor for leukoaraiosis.
MATERIALS AND METHODS:
Forty-seven patients (mean age 72.1 ± 9 years, males = 39) with carotid artery stenosis admitted for carotid endarterectomy were included and underwent an admission brain MRI/MRA. Two neuroradiologists evaluated the COW variants. FLAIR-leukoaraiosis lesion-volume was performed using a semiautomated segmentation technique. Mann-Whitney and Pearson correlations were conducted to identify the correlation between the FLAIR-leukoaraiosis lesion-volume and the COW variants. ROC analysis was performed to evaluate the AUC of FLAIR-leukoaraiosis lesion-volume and presence/absence of COW variants.
RESULTS:
Pearson correlation demonstrated that the leukoaraiosis lesion-volume is significantly associated with the COW variants number (rho = .358, P = .0215). When patients were dicotomized in two subgroups, with and without COW variants, the lesion-volume was significantly higher in the variants group (P = .0405). The ROC curve analysis showed an AUC of .688 (SE = .083, 95%CI = .525-.823) with a statistically significant P = .0225, between the presence of COW variants and the FLAIR-leukoaraiosis lesion-volume.
CONCLUSION:
The presence and the number of COW variants are associated with a higher leukoaraiosis volume in patients with significant internal carotid artery stenosis
Preserved Cochlear CISS Signal is a Predictor for Hearing Preservation in Patients Treated for Vestibular Schwannoma With Stereotactic Radiosurgery
Background:Hearing preservation is a goal for many patients with vestibular schwannoma. We examined pretreatment magnetic resonance imaging (MRI) and posttreatment hearing outcome after stereotactic radiosurgery.Methods:From 2004 to 2014, a cohort of 125 consecutive patients with vestibular schwannoma (VS) treated via stereotactic radiosurgery (SRS) were retrospectively reviewed. MRIs containing three-dimensional constructive interference in steady state or equivalent within 1 year before treatment were classified by two radiologists for pretreatment characteristics. Good hearing was defined as American Academy of Otolaryngology-Head and Neck Surgery class A. Poor hearing outcome was defined as loss of good pretreatment hearing after stereotactic radiosurgery.Results:Sixty-one patients met criteria for inclusion. Most had tumors in the distal internal auditory canal (55%), separated from the brainstem (63%), oval shape (64%) without cysts (86%), and median volume of 0.850.55cm(3). Pretreatment audiograms were performed a median of 108 +/- 173 days before stereotactic radiosurgery; 38% had good pretreatment hearing. Smaller tumor volume (p<0.005) was the only variable associated with good pretreatment hearing. 49 (80%) patients had posttreatment audiometry, with median follow-up of 197 +/- 247 days. Asymmetrically decreased pretreatment cochlear CISS signal on the side of the VS was the only variable associated with poor hearing outcome (p=0.001). Inter-rater agreement on cochlear three-dimensional constructive interference in steady state preservation was 91%.Conclusions:Decreased cochlear CISS signal may indicate a tumor's association with the cochlear neurovascular bundle, influencing endolymph protein concentration and creating an inability to preserve hearing. This important MRI characteristic can influence planning, counseling, and patient selection for vestibular schwannoma treatment