A method for obtaining diffusion-weighted images that are free from the artifacts associated with echo-planar acquisitions, such as signal pile-up and geometric warping, is introduced. It uses an ungated, multishot fast spin-echo (FSE) acquisition that is self-navigated. The phase of the refocusing pulses is alternated to minimize non-Carr-Purcell-Meiboom-Gill ( The clinical utility of diffusion-weighted imaging (DWI) is well established and extensions of this method to measure and exploit diffusion anisotropy are very exciting. Most DWI data are collected using single-shot EPI imaging, due to extreme variability in phase between applications of diffusion gradients. This can create significant motion artifacts in multiple-shot techniques in the presence of even minor, nonrepeatable motion. However, single-shot EPI methods suffer from severe warping artifact in the presence of magnetic field inhomogeneities and the significant T * 2 decay that can occur during long echo trains makes high-resolution acquisitions challenging.Multiple-shot fast spin-echo (FSE) methods for DWI have far less B 0 -related artifacts (e.g., from metal, sinuses, and eddy currents) and can be implemented with less intensive gradient requirements than those of single-shot EPI DWI. Despite this promise, multishot FSE DWI faces two major challenges.

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Background The immediate and longer-term effects of hemodialysis on cerebral circulation, cerebral structure, and cognitive function are poorly understood.Methods In a prospective observational cohort study of 97 adults (median age 59 years) receiving chronic hemodialysis, we used transcranial Doppler ultrasound to measure cerebral arterial mean flow velocity (MFV) throughout dialysis. Using a well validated neuropsychological protocol, we assessed cognitive function during and off dialysis and after 12 months of treatment. We also used brain magnetic resonance imaging (MRI) to assess atrophy, white matter hyperintensities (WMHs), and diffusion parameters, and tested correlations between MFV, cognitive scores, and changes on MRI.Results MFV declined significantly during dialysis, correlating with ultrafiltrate volumes. Percentage of decline in MFV correlated with intradialytic decline in cognitive function, including global function, executive function, and verbal fluency. At follow-up, 73 patients were available for repeat testing, 34 of whom underwent repeat MRI. In a subgroup of patients followed for 12 months of continued dialysis, percentage of decline in MFV correlated significantly with lower global and executive function and with progression of WMH burden (a marker of small vessel disease). Twelve of 15 patients who received renal transplants during follow-up had both early and follow-up off-dialysis assessments. After transplant, patients' memory (on a delayed recall test) improved significantly; increased fractional anisotropy of white matter (a measure of cerebral diffusion) in these patients correlated with improving executive function.Conclusions Patients undergoing hemodialysis experience transient decline in cerebral blood flow, correlating with intradialytic cognitive dysfunction. Progressive cerebrovascular disease occurred in those continuing dialysis, but not in transplanted patients. Cognitive function and cerebral diffusion improved after transplant.

While head motion is considered a significant problem in magnetic resonance imaging (MRI), there is no data to quantify its extent, severity, or effect on image quality. PROPELLER (Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction) MRI offers a novel means of quantifying and compensating for head motion. We performed axial T2-weighted PROPELLER (motion corrected: P-CR; uncorrected: P-UNCR) and conventional MRI (CONV), with equal scan times, in five normal volunteers and 35 clinical subjects. Volunteers were examined lying still and performing two separate head movements (shake "no" and nod "yes") to assess detection and compensation of in-plane motion by PROPELLER MRI. Images were examined by three radiologists for motion artifact and for overall image quality. Head rotation and translation was detected in all subjects during each slice acquisition, with expected changes occurring with volunteer head motion. Motion artifact was less commonly seen on PROPELLER than CONV MR ( 2 test P < 0.001). PROPELLER was preferred over CONV in all subjects (P < 0.05) and P-CR was judged superior to P-UNCR (P ‫؍‬ 0.02). Intracranial pathology was equally or better demonstrated with PROPELLER. PROPELLER MRI offers a means of quantifying head motion, reducing motion artifact, and improving image quality.

Copper is an essential trace element that is involved in a number of important enzymatic processes throughout the body. Recent single case reports and small studies have shown that deficiency of copper can cause reversible haematological changes and irreversible neurological injury. We chose to undertake a national study, looking at all cases of copper deficiency in Scotland over a 5-yr period using information from a national reference laboratory. From 16 identified patients, we determined that 86% had both haematological and neurological features of copper deficiency, while 18% had haematological features only at presentation. Twelve of the sixteen patients had high serum zinc concentrations (>18 lm/L) nine patients were using zinc-containing dental fixatives at time of diagnosis. 94% of patients had haematological features as an initial manifestation of copper deficiency, which included anaemia, thrombocytopenia and neutropenia. Patients who underwent later bone marrow testing had appearances in keeping with refractory cytopenia with multilineage dysplasia, refractory anaemia with excess of blasts, unclassified marrow dysplasia or probable myelodysplasia (MDS). 75% of patients had neurological symptoms or signs, including progressive walking difficulties and paraesthesia, or gait difficulties without sensory signs. Clinical examination was in keeping with spastic paraparesis (either with or without sensory neuropathy). Magnetic resonance imaging (MRI) showed multifocal T2 hyper intense foci in the subcortical white matter, and atrophy of the cerebrum and cerebellum was also seen on computerised tomography (CT). MRI of the spinal cord showed signal change in the dorsal columns in either the cervical or thoracic cord. 93% of cytopenias responded to copper replacement and addressing the original cause of the copper deficiency, but only 25% of patients had improvement in their neurological function, while 33% deteriorated and 42% remained unchanged. Our study demonstrates that copper deficiency is an underrecognised cause of several types of cytopenia, which are reversible but can progress to significant neurological injury if left untreated. We illustrate the importance of identifying these patients early to prevent irreversible neurological injury.

With a short increase in imaging time, PROPELLER MR imaging offers better image quality and detection of acute cerebral infarction than does echo-planar MR imaging.

Results suggest that in neonates and infants, water diffusion is highly dependent on both subject age and brain location.

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