The relation between cognitive dysfunction and diffusion tensor imaging parameters in traumatic brain injury.

PURPOSE OF THE STUDY: To investigate the association among global and regional white matter fractional anisotropy (FA) values following traumatic brain injury (TBI) and cognitive functioning. MATERIALS AND METHODS: This research was conducted in an urban rehabilitation hospital. Participants included adults who were healthy controls (n = 18) or who had a TBI (n = 27). Diffusion tensor imaging using a Siemens VERIO 3T scanner and calculation of global and regional FA values were undertaken. FA values were correlated with neuropsychological test scores and injury severity variables. Logistic regression and receiver operating characteristic (ROC) curve analysis were used to investigate discriminative ability of the FA values. Neuropsychological measures, including the Symbol Digit Modalities Test (SDMT), Trail Making Test, Wechsler Test of Adult Reading, California Verbal Learning Test 2nd Edition, Digit Vigilance Test, and Wisconsin Card Sorting Test, comprised the cognitive measures. RESULTS: Within the TBI group, regional FA values were significantly lower across regions compared with controls; global FA and five brain regions were associated with SDMT scores. The FA value within the body of the corpus callosum (CC) yielded excellent discrimination between groups. CONCLUSIONS: Convergent findings support the discriminability and potential clinical utility of the CC body FA value in the context of TBI.

Thickness of soft tissue of lower extremities measured with magnetic resonance imaging as a new indicator for staging unilateral secondary lower extremity lymphedema.

BACKGROUND: Chronic progressive swelling of the lower extremity due to secondary lower extremity lymphedema (LEL) can affect a patient's quality of life, both physically and psychologically. A feasible and reproducible method for detecting and staging LEL will facilitate decision-making about appropriate management strategies. PURPOSE: To determine whether the thickness of the soft tissues of the lower extremities, measured with magnetic resonance imaging (MRI), could stage unilateral secondary LEL. MATERIAL AND METHODS: Seventy-two women with unilateral LEL and 22 participants without LEL underwent lower extremity MRI after treatment of uterine malignancies. LEL was classified clinically as stage 0, 1, 2, or 3. On fat-suppressed T2-weighted mid-axial images of calves and thighs, the total thickness of the soft tissue (TT), muscle thickness (MT), subcutaneous tissue thickness (STT), and the differences in TT (DTT), MT (DMT), and STT (DSTT) values and corresponding measurements in the contralateral lower extremity, were obtained and analyzed statistically for staging LEL. RESULTS: There was a trend for the TT and STT of the affected calf and thigh to increase with increasing LEL stage. These parameters were strongly and moderately correlated with LEL stage, respectively (P < 0.001). Both the DTT and DSTT of the calves or thighs were strongly correlated with LEL stage (P < 0.001). Among the parameters, the DSTT of the calves could best stage LEL, with an area under the receiver operating curve of more than 0.89. CONCLUSION: The DSTT of the calves could be recommended as an informative indicator for staging LEL.

Quantitative T2 changes and susceptibility-weighted magnetic resonance imaging in murine pregnancy.

OBJECTIVE: To evaluate gestational age-dependent changes in the T2 relaxation time in normal murine placentas in vivo. The role of susceptibility-weighted imaging (SWI) in visualization of the murine fetal anatomy was also elucidated. METHODS: Timed-pregnant CD-1 mice at gestational day (GD) 12 and GD17 underwent magnetic resonance imaging. Multi-echo spin echo and SWI data were acquired. The placental T2 values on GD12 and GD17 were quantified. To account for the influence of systemic maternal physiological factors on placental perfusion, maternal muscle was used as a reference for T2 normalization. A linear mixed-effects model was used to fit the normalized T2 values, and the significance of the coefficients was tested. Fetal SWI images were processed and reviewed for venous vasculature and skeletal structures. RESULTS: The average placental T2 value decreased significantly on GD17 (40.17 ± 4.10 ms) compared to the value on GD12 (55.78 ± 8.13 ms). The difference in normalized T2 values also remained significant (p = 0.001). Using SWI, major fetal venous structures like the cardinal vein, the subcardinal vein, and the portal vein were visualized on GD12. In addition, fetal skeletal structures could also be discerned on GD17. CONCLUSION: The T2 value of a normal murine placenta decreases with advancing gestation. SWI provided clear visualization of the fetal venous vasculature and bony structures. © 2014 S. Karger AG, Basel.

Direct portal vein thrombosis visualization with t2*--weighted magnetic resonance imaging.

BACKGROUND AND PURPOSE: To investigate the feasibility of direct magnetic resonance portal vein thrombosis (PVT) visualization with T2*-weighted imaging (T2*WI) without contrast agent. METHODS: Thirty patients with PVT were included in this study. All of them were imaged with contrast-enhanced CT (CE-CT) as well as non-contrast MRI T1, T2 and T2*WI. Imaging data was independently analyzed by two experienced radiologists. T2*WI of all PVT was compared slice-by-slice with each of the comparison sequences (T1WI, T2WI and CE-CT) on the following categories: the location, size, boundary, and conspicuity of thrombus and portal veins. RESULTS: The average score of PVT visualization in T2*WI was higher than T1WI and T2WI in location, size, boundary and conspicuity (t = 7.54 - 84.16, P<0.05), and higher than CE-CT in boundary and conspicuity (t = 3.03- 6.98, P<0.05). For portal vein visualization, there was no significant score difference in left, middle and right portal veins between CE-CT and T2*WI (t = -1.76- 1.35, P>0.05). CONCLUSIONS: Our results suggest T2*WI can characterize PVT accurately with high quality without the use of intravenous contrast agents.

Clinical improvement after extracranial venoplasty in multiple sclerosis.

PURPOSE: This study proposed to prospectively evaluate safety and clinical changes in outpatient endovascular treatment in patients with multiple sclerosis (MS) and chronic cerebrospinal venous insufficiency (CCSVI). MATERIALS AND METHODS: Two hundred fifty-nine patients with MS were followed with the Multiple Sclerosis Impact Scale (MSIS-29) before and for 1 and 6 months after treatment of extracranial internal jugular vein and azygos vein stenoses and occlusions using venous angioplasty, as well as stent placement in 2.5% of patients. Before treatment, the patients were tested with magnetic resonance (MR) venography and flow quantification. RESULTS: We found statistically significant improvements in the MSIS-29 scores (P < .01) at both 1 and 6 months. At 1 and 6 months, 67.9% and 53.6% were improved on the physical scale, respectively, and 53.0% and 44.4% were improved on the psychological scale, respectively. Women showed greater improvement than did men on the physical scale at 6 months (P = .01). Patients with primary progressive MS (PPMS) showed less improvement than did those with relapsing-remitting MS (RRMS) on the psychological scale at 1 month, and venoplasty treatment of more vein sites versus fewer vein sites showed greater improvement on the physical scale at both 1 and 6 months. Fifteen patients (6.3%) reported recurrent symptoms after clinical improvement and were treated again. There was one serious adverse event, a deep venous thrombosis at the catheter insertion site, which resolved with treatment. CONCLUSIONS: Endovascular treatment of CCSVI in patients with MS appears to be a safe procedure resulting in significant clinical improvement.

Non-invasive measurement of oxygen saturation in the spinal vein using SWI: quantitative evaluation under conditions of physiological and caffeine load.

Susceptibility-weighted imaging (SWI) has been used for quantitative and non-invasive measurement of blood oxygen saturation in the brain. In this study, we used SWI for quantitative measurement of oxygen saturation in the spinal vein to look for physiological- or caffeine-induced changes in venous oxygenation. SWI measurements were obtained for 5 healthy volunteers using 1.5-T MR units, under 1) 3 kinds of physiological load (breath holding, Bh; hyperventilation, Hv; and inspiration of highly concentrated oxygen, Ox) and 2) caffeine load. Oxygen saturation in the anterior spinal vein (ASV) was calculated. We evaluated changes in oxygen saturation induced by physiological load. We also evaluated the time-course of oxygen saturation after caffeine intake. For the physiological load measurements, the average oxygen saturation for the 5 subjects was significantly lower in Hv (0.75) and significantly higher in Bh (0.84) when compared with control (0.80). There was no significant difference between Ox (0.81) and control. Oxygen saturation gradually decreased after caffeine intake. The average values of oxygen saturation were 0.79 (0 min), 0.76 (20 min), 0.74 (40 min), and 0.73 (60 min), respectively. We demonstrated a significant difference in oxygen saturation at 40 and 60 min after caffeine intake when compared with 0 min. In conclusion, we demonstrated the feasibility of using SWI for non-invasive measurement of oxygen saturation in the spinal vein. We showed changes in oxygen saturation under physiological as well as caffeine load and suggest that this method is a useful tool for the clinical evaluation of spinal cord oxygenation.

Brain iron detected by SWI high pass filtered phase calibrated with synchrotron X-ray fluorescence.

PURPOSE: To test the ability of susceptibility weighted images (SWI) and high pass filtered phase images to localize and quantify brain iron. MATERIALS AND METHODS: Magnetic resonance (MR) images of human cadaver brain hemispheres were collected using a gradient echo based SWI sequence at 1.5T. For X-ray fluorescence (XRF) mapping, each brain was cut to obtain slices that reasonably matched the MR images and iron was mapped at the iron K-edge at 50 or 100 microm resolution. Iron was quantified using XRF calibration foils. Phase and iron XRF were averaged within anatomic regions of one slice, chosen for its range of iron concentrations and nearly perfect anatomic correspondence. X-ray absorption spectroscopy (XAS) was used to determine if the chemical form of iron was different in regions with poorer correspondence between iron and phase. RESULTS: Iron XRF maps, SWI, and high pass filtered phase data in nine brain slices from five subjects were visually very similar, particularly in high iron regions. The chemical form of iron could not explain poor matches. The correlation between the concentration of iron and phase in the cadaver brain was estimated as c(Fe) [microg/g tissue] = 850Deltavarpi + 110. CONCLUSION: The phase shift Deltavarpi was found to vary linearly with iron concentration with the best correspondence found in regions with high iron content.

Hearing impairment after subarachnoid hemorrhage.

Background: Subarachnoid hemorrhage (SAH) survivors experience significant neurological disability, some of which is under-recognized by neurovascular clinical teams. We set out to objectively determine the occurrence of hearing impairment after SAH, characterize its peripheral and/or central origin, and investigate likely pathological correlates. Methods: In a case-control study (n = 41), participants were asked about new onset hearing difficulty 3 months post-SAH, compared with pre-SAH. Formal audiological assessment included otoscopy, pure tone audiometry, a questionnaire identifying symptoms of peripheral hearing loss and/or auditory processing disorder, and a test of speech understanding in noise. A separate cohort (n = 21) underwent quantitative susceptibility mapping (QSM) of the auditory cortex 6 months after SAH, for correlation with hearing difficulty. Results: Twenty three percent of SAH patients reported hearing difficulty that was new in onset post-SAH. SAH patients had poorer pure tone thresholds compared to controls. The proportion of patients with peripheral hearing loss as defined by the World Health Organization and British Audiological Society was however not increased, compared to controls. All SAH patients experienced symptoms of auditory processing disorder post-SAH, with speech-in-noise test scores significantly worse versus controls. Iron deposition in the auditory cortex was higher in patients reporting hearing difficulty versus those who did not. Conclusion: This study firmly establishes hearing impairment as a frequent clinical feature after SAH. It primarily consists of an auditory processing disorder, mechanistically linked to iron deposition in the auditory cortex. Neurovascular teams should inquire about hearing, and refer SAH patients for audiological assessment and management.

Imaging lymphatic system in breast cancer patients with magnetic resonance lymphangiography.

OBJECTIVE: To investigate the feasibility of gadolinium (Gd) contrast-enhanced magnetic resonance lymphangiography (MRL) in breast cancer patients within a typical clinical setting, and to establish a Gd-MRL protocol and identify potential MRL biomarkers for differentiating metastatic from non-metastatic lymph nodes. MATERIALS AND METHODS: 32 patients with unilateral breast cancer were enrolled and divided into 4 groups of 8 patients. Groups I, II, and III received 1.0, 0.5, and 0.3 ml of intradermal contrast; group IV received two 0.5 ml doses of intradermal contrast. MRL images were acquired on a 3.0 T system and evaluated independently by two radiologists for the number and size of enhancing lymph nodes, lymph node contrast uptake kinetics, lymph vessel size, and contrast enhancement patterns within lymph nodes. RESULTS: Group III patients had a statistically significant decrease in the total number of enhancing axillary lymph nodes and lymphatic vessels compared to all other groups. While group IV patients had a statistically significant faster time to reach the maximum peak enhancement over group I and II (by 3 minutes), there was no other statistically significant difference between imaging results between groups I, II, and IV. 27 out of 128 lymphatic vessels (21%) showed dilatation, and all patients with dilated lymphatic vessels were pathologically proven to have metastases. Using the pattern of enhancement defects as the sole criterion for identifying metastatic lymph nodes during Gd-MRL interpretation, and using histopathology as the gold standard, the sensitivity and specificity were estimated to be 86% and 95%, respectively. CONCLUSION: Gd-MRL can adequately depict the lymphatic system, can define sentinel lymph nodes, and has the potential to differentiate between metastatic and non-metastatic lymph nodes in breast cancer patients.