BACKGROUND AND PURPOSE:Traumatic axonal injury is a primary brain abnormality in head trauma and is characterized by reduction of fractional anisotropy (FA) on diffusion tensor imaging (DTI). Our hypothesis was that patients with mild traumatic brain injury (TBI) have widespread brain white matter regions of reduced FA involving a variety of fiber bundles and show fiber disruption on fiber tracking in a minority of these regions.
BACKGROUND AND PURPOSE:The corpus callosum is an important predilection site for traumatic axonal injury but may be unevenly affected in head trauma. We hypothesized that there were local differences in axonal injury within the corpus callosum as investigated with diffusion tensor imaging (DTI), varying among patients with differing severity of traumatic brain injury (TBI).
Magnetic resonance (MR) imaging with pulsed arterial spin labeling (ASL) was performed at six different inversion times in nine patients with internal carotid artery (ICA) occlusion and in 11 control subjects. The hospital's commission on scientific research on human subjects approved the study protocol, and all study subjects gave informed consent. Cerebral blood flow (CBF) in the middle cerebral artery territories was calculated from the combined signal intensities measured with ASL at the multiple inversion times. In the patients with ICA occlusion, mean CBF values were decreased in the gray matter of the hemisphere ipsilateral to the occlusion, as compared with values in the gray matter of the contralateral hemisphere (P < .05) and with values in the gray matter of the control subjects (P < .05). Quantification of CBF with ASL at multiple inversion times can compensate for the blood transit delays in patients with ICA occlusion.
Background and Purpose-The purpose of the present study was to assess whether the direction of flow via the circle of Willis and the ophthalmic artery (OphA) changed over time in patients with a symptomatic occlusion of the internal carotid artery (ICA) who did not experience recurrent cerebral ischemic symptoms. Methods-Sixty-two patients with a symptomatic ICA occlusion were investigated within 6 months after symptoms occurred. The investigations were repeated after 6 and 12 months. The directions of flow in the A1 segment and the posterior communicating artery (PCoA), both on the side of the symptomatic ICA occlusion, were assessed with the use of magnetic resonance angiography. The pattern of collateral flow via the circle of Willis was categorized as via the A1 segment only, via the PCoA only, via the A1 segment plus the PCoA, or no collateral flow via the circle of Willis. The direction of flow in the OphA was investigated with transcranial Doppler sonography. CO 2 reactivity was determined with transcranial Doppler sonography to investigate whether changes in flow patterns were accompanied by changes in cerebrovascular reactivity. Results-There were no statistically significant changes over time in the direction of blood flow in the A1 segment and the PCoA or in the pattern of collateral flow via the circle of Willis. On average, 72% of patients with a unilateral ICA occlusion (nϭ41) had willisian collateral flow compared with 37% of patients with a bilateral ICA occlusion (nϭ21; PϽ0.05). Patients with a unilateral ICA occlusion tended to a lower prevalence of reversed flow via the OphA over time. CO 2 reactivity did not change significantly in any patient group. In patients with a unilateral ICA occlusion, decreased CO 2 reactivity was associated with a higher prevalence of absent willisian collateral flow and a lower prevalence of collateral flow via the A1 segment plus the PCoA. Conclusions-The absence of recurrent cerebral ischemic symptoms in patients with a symptomatic ICA occlusion is not associated with an improvement in collateral flow via the circle of Willis or the OphA during 1.5-year follow-up.
Several studies have investigated the T1 and T2 relaxation time of choline, creatine and N-acetyl aspartate in cerebral white matter in normal human subjects. However, these studies demonstrate a large variation in T1 and T2 values. In the present study, relaxation times of choline, creatine and N-acetyl aspartate were determined in cerebral white matter in 15 control subjects (age 21 +/- 2 y, mean +/- SD) at 1.5 T. Using PRESS, seven or eight data points were obtained to fit the T1 and T2 relaxation curves to, respectively. The mean voxel size was 14 cm3. The T1 relaxation times of choline, creatine and N-acetyl aspartate were 1091 +/- 132 (mean +/- SD), 1363 +/- 137 and 1276 +/- 132 ms. The T2 relaxation times were 352 +/- 52, 219 +/- 29 and 336 +/- 46 ms, respectively.
ObjectivesTo describe the development of the Dutch Radiology Progress Test (DRPT) for knowledge testing in radiology residency training in The Netherlands from its start in 2003 up to 2016.MethodsWe reviewed all DRPTs conducted since 2003. We assessed key changes and events in the test throughout the years, as well as resident participation and dispensation for the DRPT, test reliability and discriminative power of test items.ResultsThe DRPT has been conducted semi-annually since 2003, except for 2015 when one digital DRPT failed. Key changes in these years were improvements in test analysis and feedback, test digitalization (2013) and inclusion of test items on nuclear medicine (2016). From 2003 to 2016, resident dispensation rates increased (Pearson’s correlation coefficient 0.74, P-value <0.01) to maximally 16 %. Cronbach´s alpha for test reliability varied between 0.83 and 0.93. The percentage of DRPT test items with negative item-rest-correlations, indicating relatively poor discriminative power, varied between 4 % and 11 %.ConclusionsProgress testing has proven feasible and sustainable in Dutch radiology residency training, keeping up with innovations in the radiological profession. Test reliability and discriminative power of test items have remained fair over the years, while resident dispensation rates have increased.Key Points • Progress testing allows for monitoring knowledge development from novice to senior trainee. • In postgraduate medical training, progress testing is used infrequently. • Progress testing is feasible and sustainable in radiology residency training.
Background and Purpose-We sought to investigate whether in patients with a symptomatic internal carotid artery (ICA) occlusion, endarterectomy of a severe stenosis of the contralateral carotid artery can establish long-term cerebral hemodynamic improvement. Methods-Nineteen patients were studied on average 1 month before and 6 months after contralateral carotid endarterectomy (CEA). Volume flow in the main extracranial and intracranial arteries was measured with MR angiography. Collateral flow via the circle of Willis and the ophthalmic arteries was studied with MR angiography and transcranial Doppler sonography, respectively. Cerebral metabolism and CO 2 vasoreactivity were investigated with MR spectroscopy and transcranial Doppler sonography, respectively. Twelve nonoperated patients with a symptomatic ICA occlusion and contralateral ICA stenosis, who were matched for age and sex, served as control patients. Results-In patients who underwent surgery, flow in the operated ICA increased significantly (PϽ0.05) and flow in the basilar artery decreased significantly (PϽ0.01) after CEA. On the occlusion side, mean flow in the middle cerebral artery increased significantly from 71 to 85 mL/min (PϽ0.05) after CEA. The prevalence of collateral flow via the anterior communicating artery to the occlusion side increased significantly (47% before and 84% after CEA; PϽ0.05), while the prevalence of reversed ophthalmic artery flow on the operation side decreased significantly (42% before and 5% after CEA; PϽ0.05). In the hemisphere on the side of the ICA occlusion, lactate was no longer detected after CEA in 80% of operated patients, whereas it was no longer detected over time in 14% of nonoperated patients (PϽ0.05). CO 2 reactivity increased significantly in operated patients in both hemispheres (PϽ0.01). Conclusions-Contralateral
• 7.0 T MRI enables ultra-high-resolution imaging of the pituitary gland. • 7.0 T MRI is appropriate to visualize normal pituitary gland anatomy. • The pituitary protocol consists of a T 1 -MPIR-TSE and a T 2 -TSE sequence. • In four patients, a suspected ACTH-producing microadenoma was visualized at 7.0 T. • Histopathology confirmed three of four lesions to be ACTH-producing microadenomas.
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