Usefulness of high b-value diffusion-weighted MRI in the diagnosis of Creutzfeldt-Jakob disease

Background: Current diagnostic criteria of probable Creutzfeldt-Jakob disease (CJD) include a combination of clinical, EEG and analytic data. Recent data indicate that brain MRI including fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted imaging (DWI) sequences can be a valid and reliable tool for the diagnosis of CJD. We describe our experience with high b-value (3000s/mm2) diffusion-weighted imaging (DWI) in patients with probable or definite CJD and compare it with standard b-value (1000s/mm2) DWI. Methods: We performed a retrospective analysis of patients admitted to our Hospital Service between 2002 and 2008 with a final diagnosis of probable or definite CJD. Patients were examined using either a 1.5 Tesla or a 3 Tesla MRI. The MRI protocol included T1-weigthed spin-echo sequences, T2-weighted fast spin-echo, FLAIR and DWI sequences with high b-value and standard b-value. Results: During the study period there were 7 patients with probable or definite CJD. Only 3 patients (43%) showed changes on FLAIR sequence consistent with CJD. All the cases were detected with high b-value DWI, including 2 cases (28%) that would have been missed using standard b-value (1000s/mm2) DWI. In all the patients the changes were more conspicuous and extensive at high b-value DWI (b=3000s/mm2). Conclusion: Our data indicate that high b-value DWI may improve the sensitivity of brain MRI for the diagnosis of CJD, allowing the detection of some cases that would have been overlooked by conventional sequences. Resumen: Introducción: Los criterios diagnósticos actuales de la enfermedad de Creutzfeldt-Jakob (ECJ) probable incluyen la combinación de datos clínicos, electroencefalográficos y analíticos. En los últimos años se ha demostrado que la RM craneal con el uso de secuencias FLAIR y difusión (DWI) puede ser una herramienta útil en el diagnóstico de esta enfermedad. Describimos nuestra experiencia en la utilización de la DWI convencional (b: 1000s/mm2) y DWI con valor b alto (3000s/mm2) en el diagnóstico de la ECJ probable o definitiva. Pacientes y métodos: Realizamos un análisis retrospectivo de los pacientes atendidos en nuestro hospital diagnosticados de ECJ probable o definitiva, desde el año 2002 al 2008. A todos ellos se les realizó una RM craneal con un protocolo que incluyó secuencias potenciadas en T1, T2, FLAIR y dos secuencias DWI, una con valor b convencional (1000s/mm2) y otra con valor b alto (3000s/mm2). Resultados: Se atendieron a 7 pacientes con diagnóstico de ECJ probable o definitiva. En tres de ellos (43%) la secuencia FLAIR mostró cambios de señal compatibles con ECJ. En todos los pacientes en la secuencia DWI con valor b alto se observaron alteraciones características de la enfermedad, incluyendo dos casos (28%) en los que todas las secuencias realizadas, incluida la DWI convencional, fueron normales. Adicionalmente en los 7 casos (100%) las alteraciones radiológicas fueron más fáciles de identificar y más extensas con valores altos b de DWI. Conclusión: La utilización de un valor b alto (3000s/mm2) en la secuencia DWI puede aumentar la sensibilidad de la RM craneal en el diagnóstico de la ECJ, permitiendo la detección de casos en los que la DWI convencional es normal. Keywords: Creutzfeldt-Jakob disease, MRI, Magnetic resonance imaging, Diffusion-weighted imaging, DWI, b value, Palabras clave: Enfermedad de Creutzfeldt-Jakob, Resonancia magnética cerebral, Secuencias potenciadas en difusión, DWI, Valor

Utilidad de la resonancia magnética cerebral con secuencia de difusión y valor b alto en el diagnóstico de la enfermedad de Creutzfeldt-Jakob

Resumen: Introducción: los criterios diagnósticos actuales de la enfermedad de Creutzfeldt-Jakob (ECJ) probable incluyen la combinación de datos clínicos, electroencefalográficos y analíticos. En los últimos años se ha demostrado que la RM craneal con el uso de secuencias FLAIR y difusión (DWI) puede ser una herramienta útil en el diagnóstico de esta enfermedad. Describimos nuestra experiencia en la utilización de la DWI convencional (b: 1000 s/mm2) y DWI con valor b alto (3000 s/mm2) en el diagnóstico de la ECJ probable o definitiva. Pacientes y métodos: realizamos un análisis retrospectivo de los pacientes atendidos en nuestro hospital diagnosticados de ECJ probable o definitiva, desde el año 2002 al 2008. A todos ellos se les realizó una RM craneal con un protocolo que incluyó secuencias potenciadas en T1, T2, FLAIR y dos secuencias DWI, una con valor b convencional (1000 s/mm2) y otra con valor b alto (3000 s/mm2). Resultados: se atendieron a 7 pacientes con diagnóstico de ECJ probable o definitiva. En tres de ellos (43%) la secuencia FLAIR mostró cambios de señal compatibles con ECJ. En todos los pacientes en la secuencia DWI con valor b alto se observaron alteraciones características de la enfermedad, incluyendo dos casos (28%) en los que todas las secuencias realizadas, incluida la DWI convencional, fueron normales. Adicionalmente en los 7 casos (100%) las alteraciones radiológicas fueron más fáciles de identificar y más extensas con valores altos b de DWI. Conclusión: la utilización de un valor b alto (3000 s/mm2) en la secuencia DWI puede aumentar la sensibilidad de la RM craneal en el diagnóstico de la ECJ, permitiendo la detección de casos en los que la DWI convencional es normal. Abstract: Background: current diagnostic criteria of probable Creutzfeldt-Jakob disease (CJD) include a combination of clinical, EEG and analytic data. Recent data indicate that brain MRI including fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted imaging (DWI) sequences can be a valid and reliable tool for the diagnosis of CJD. We describe our experience with high b-value (3000 s/mm2) diffusion-weighted imaging (DWI) in patients with probable or definite CJD and compare it with standard b-value (1000 s/mm2) DWI. Methods: we performed a retrospective analysis of patients admitted to our Hospital Service between 2002 and 2008 with a final diagnosis of probable or definite CJD. Patients were examined using either a 1.5 Tesla or a 3 Tesla MRI. The MRI protocol included T1-weigthed spin-echo sequences, T2-weighted fast spin-echo, FLAIR and DWI sequences with high b-value and standard b-value. Results: during the study period there were 7 patients with probable or definite CJD. Only 3 patients (43%) showed changes on FLAIR sequence consistent with CJD. All the cases were detected with high b-value DWI, including 2 cases (28%) that would have been missed using standard b-value (1000 s/mm2) DWI. In all the patients the changes were more conspicuous and extensive at high b-value DWI (b = 3000 s/mm2). Conclusion: our data indicate that high b-value DWI may improve the sensitivity of brain MRI for the diagnosis of CJD, allowing the detection of some cases that would have been overlooked by conventional sequences. Palabras clave: Enfermedad de Creutzfeldt-Jakob, Rsonancia magnética cerebral, Secuencias potenciadas en difusión, DWI, Valor b, Keywords: Creutzfeldt-Jakob disease, MRI, Magnetic resonance imaging, Diffusion-weighted imaging, DWI, b valu

Overview of JET results

High density and high confinement operation in ELMy H-mode is confirmed at or above the normalized parameters foreseen for the ITER operating point (H98(y,2) 3c 1, n/nGW 3c 1, \u3b2N > 1.8 at q95 3c 3). The scaling of the ELMy H-mode with \u3b2N could be more favourable than that predicted by the IPB98(y,2) scaling. In ELMy H-mode, ion cyclotron current drive (ICCD) control of large sawteeth stabilized by fast particle has been demonstrated and the underlying neo-classical tearing modes (NTMs) and sawtooth physics is being refined. At high-density, Type I ELMy H-modes show trends that would lead to marginally acceptable ELMs on ITER. Type II ELM regime has been produced, though under very restrictive conditions. Type III ELMy operation with radiation fractions up to 95% has been demonstrated by seeding of N2 in H-modes and could extrapolate to Q = 10 ITER operation, albeit at high current (17 MA). The mitigation of Type I ELMs, nevertheless, remains a challenge. Considerable progress has been obtained in internal transport barrier (ITB) plasmas, with operation at central densities close to the Greenwald density or/and low toroidal rotation or/and high triangularity. Demonstrations of full current drive and successful simultaneous real time control of safety factor and temperature profiles have been achieved in ITB plasmas. Physics of resistive wall modes (RWMs) has been compared with theory, showing favourable scaling for ITER. High \u3b2N 3c 2.8 operation of hybrid modes (also called improved H-modes) has been obtained with dominant neutral beam heating. Hybrid modes with dominant ion cyclotron resonance heating (ICRH) have also been achieved. Trace tritium experiments yielded valuable information on particle transport in H-mode, ITB and hybrid regimes. In Type I ELMy plasmas, successful tests of the conjugate-T ICRH scheme have been achieved as well as lower hybrid coupling at ITER-relevant 10\u201311 cm distances. Reduced D and T fuel retention has been observed, which could relate to operation with vertical targets in the divertor and/or lower (ITER-like) vessel temperature. It is confirmed that erosion occurs predominantly on the main chamber surfaces, with possible benefits for T retention in ITER, although consequences for the metallic first wall lifetime need to be assessed. Disruption and ELM studies indicate that transient power deposition could be less constraining than expected for the ITER divertor, but more challenging for the metallic first wall. Alpha particle tomography and direct observation of alpha particle slowing down have been made possible by \u3b3 -spectroscopy. Measurements of Alfve \u301n cascades have been improved by a new interferometric technique. Promising tests of ITER relevant neutron counting detectors have been conducted