Capturing fast relaxing spins with SWIFT adiabatic rotating frame spin-lattice relaxation (T1ρ) mapping.

Rotating frame spin-lattice relaxation, with the characteristic time constant T1ρ, provides a means to access motion-restricted (slow) spin dynamics in MRI. As a result of their restricted motion, these spins are sometimes characterized by a short transverse relaxation time constant T2 and thus can be difficult to detect directly with conventional image acquisition techniques. Here, we introduce an approach for three-dimensional adiabatic T1ρ mapping based on a magnetization-prepared sweep imaging with Fourier transformation (MP-SWIFT) sequence, which captures signal from almost all water spin populations, including the extremely fast relaxing pool. A semi-analytical procedure for T1ρ mapping is described. Experiments on phantoms and musculoskeletal tissue specimens (tendon, articular and epiphyseal cartilages) were performed at 9.4 T for both the MP-SWIFT and fast spin echo (FSE) read outs. In the phantom with liquids having fast molecular tumbling and a single-valued T1ρ time constant, the measured T1ρ values obtained with MP-SWIFT and FSE were similar. Conversely, in normal musculoskeletal tissues, T1ρ values measured with MP-SWIFT were much shorter than the values obtained with FSE. Studies of biological tissue specimens demonstrated that T1ρ-weighted SWIFT provides higher contrast between normal and diseased tissues relative to conventional acquisitions. Adiabatic T1ρ mapping with SWIFT readout captures contributions from the otherwise undetected fast relaxing spins, allowing more informative T1ρ measurements of normal and diseased states.

Treatment effects in a transgenic mouse model of Alzheimer's disease: a magnetic resonance spectroscopy study after passive immunization.

Despite the enormous public health impact of Alzheimer's disease (AD), no disease-modifying treatment has yet been proven to be efficacious in humans. A rate-limiting step in the discovery of potential therapies for humans is the absence of efficient non-invasive methods of evaluating drugs in animal models of disease. Magnetic resonance spectroscopy (MRS) provides a non-invasive way to evaluate the animals at baseline, at the end of treatment, and serially to better understand treatment effects. In this study, MRS was assessed as potential outcome measure for detecting disease modification in a transgenic mouse model of AD. Passive immunization with two different antibodies, which have been previously shown to reduce plaque accumulation in transgenic AD mice, was used as intervention. Treatment effects were detected by MRS, and the most striking finding was attenuation of myo-inositol (mIns) increases in APP-PS1 mice with both treatments. Additionally, a dose-dependent effect was observed with one of the treatments for mIns. MRS appears to be a valid in vivo measure of anti-Aß therapeutic efficacy in pre-clinical studies. Because it is noninvasive, and can detect treatment effects, use of MRS-based endpoints could substantially accelerate drug discovery.

Endoscopic carpal tunnel release in Jamaica--seven years experience.

OBJECTIVE: To assess the patient profile and outcome of treatment, by endoscopic release, of patients with carpal tunnel syndrome. METHODS: A descriptive study was done using data from two sets of patients who had endoscopic carpal tunnel release in Jamaica from 2004 to 2006 and 2006 to 2010. The medical records of patients who had a diagnosis of carpal tunnel syndrome using symptoms, clinical signs and confirmation by nerve conduction test were reviewed. The data were analysed using SPSS and Micosoft Excel. RESULTS: A total of 68 patients with 75 cases of carpal tunnel syndrome were done. Fifty-two (76%) of these patients were females and about 50% were older than 41 years old. There were 61 (90%) unilateral cases. Of these, the majority of cases affected the right hand. All patients had improvement in symptoms after one week, required minimal analgesic use, had good compliance with rehabilitation and returned to work after about two weeks. There were three cases of pilar tenderness, two cases of transient paraesthesia in the index finger which resolved after three weeks. There were three failed cases from the first series which had to be converted to open carpal tunnel release. The complication rate was 6.7%. No serious complications occurred in the second series and all were treated successfully without interventional surgery. The rate of conversion to open release was 4%. CONCLUSION: Carpal tunnel affects mostly middle aged females and when treatment is done by endoscopic release, there is a fast resolution of symptoms and early return to work.

Endoscopic carpal tunnel release in jamaica: seven years experience / Liberación endoscópica del túnel carpiano en jamaica: siete anos de experiencia

OBJECTIVE: To assess the patient profile and outcome of treatment, by endoscopic release, of patients with carpal tunnel syndrome. METHODS: A descriptive study was done using data from two sets ofpatients who had endoscopic carpal tunnel release in Jamaica from 2004 to 2006 and 2006 to 2010. The medical records of patients who had a diagnosis of carpal tunnel syndrome using symptoms, clinical signs and confirmation by nerve conduction test were reviewed. The data were analysed using SPSS and Micosoft Excel®. RESULTS: A total of 68 patients with 75 cases of carpal tunnel syndrome were done. Fifty-two (76%) of these patients were females and about 50% were older than 41 years old. There were 61 (90%) unilateral cases. Of these, the majority of cases affected the right hand. All patients had improvement in symptoms after one week, required minimal analgesic use, had good compliance with rehabilitation and returned to work after about two weeks. There were three cases of pilar tenderness, two cases of transient paraesthesia in the index finger which resolved after three weeks. There were three failed cases from the first series which had to be converted to open carpal tunnel release. The complication rate was 6.7%. No serious complications occurred in the second series and all were treated successfully without interventional surgery. The rate ofconversion to open release was 4%. CONCLUSION: Carpal tunnel affects mostly middle aged females and when treatment is done by endoscopic release, there is a fast resolution of symptoms and early return to work.

OBJETIVO: Evaluar el perfil del paciente y el resultado clínico del tratamiento de pacientes con el síndrome del túnel carpiano tratados mediante liberación endoscópica. MÉTODOS: Se llevó a cabo un estudio descriptivo, usando datos de dos conjuntos de pacientes a quienes se les realizó una liberación endoscópica del túnel carpiano en Jamaica entre 2004 y 2006; 2006 y 2010. Se revisaron las historias clínicas de pacientes con un diagnóstico de síndrome del túnel carpiano, usando síntomas, senales clínicas y confirmación mediante la prueba de conducción de nervio. Los datos fueron analizados usando SPSS y Micosoft Excel®. RESULTADOS: Se analizó un total de 68 pacientes con 75 casos de síndrome del túnel carpiano. Cincuenta y dos (76%) de estas pacientes fueron mujeres, y aproximadamente 50% tenían más de 41 anos de edad. Hubo 61 (90%) casos unilaterales. De éstos, la mayoría de casos tuvo afectación de la mano derecha. Todos los pacientes experimentaron una mejoría en los síntomas después de una semana; necesitaron un uso mínimo de analgésicos, cumplieron bien con la rehabilitación, y regresaron al trabajo luego de dos semanas aproximadamente. Hubo tres casos de sensibilidad del talón de la mano, y dos casos deparestesia transitoria del dedo índice, que se resolvieron después de tres semanas. Hubo tres casos fallidos que tuvieron que ser convertidos en liberación abierta del túnel carpiano. La tasa de complicación fue 6.7%. No ocurrió ninguna complicación seria en esta serie, y todas fueron tratadas exitosamente sin intervención quirúrgica. La tasa de conversión para abrir la liberación fue 4%. CONCLUSIÓN: El túnel carpiano afecta principalmente a las mujeres de mediana edad, y cuando el tratamiento se realiza mediante liberación endoscópica, se produce una resolución rápida de los síntomas y un temprano regreso al trabajo.

Regional differences in MRI detection of amyloid plaques in AD transgenic mouse brain.

Our laboratory and others have reported the ability to detect individual Alzheimer's disease (AD) amyloid plaques in transgenic mouse brain in vivo by magnetic resonance imaging (MRI). Since amyloid plaques contain iron, most MRI studies attempting to detect plaques in AD transgenic mouse brain have employed techniques that exploit the paramagnetic effect of iron and have had mixed results. In the present study, using five-way anatomic spatial coregistration of MR images with three different histological techniques, properties of amyloid plaques in AD transgenic mouse brain were revealed that may explain their variable visibility in gradient- and spin-echo MR images. The results demonstrate differences in the visibility of plaques in the cortex and hippocampus, compared to plaques in the thalamus, by the different MRI sequences. All plaques were equally detectable by T(2)SE, while only thalamic plaques were reliably detectable by T(2)*GE pulse sequences. Histology revealed that cortical/hippocampal plaques have low levels of iron while thalamic plaques have very high levels. However, the paramagnetic effect of iron does not appear to be the sole factor leading to the rapid decay of transverse magnetization (short T(2)) in cortical/hippocampal plaques. Accordingly, MRI methods that rely less on iron magnetic susceptibility effect may be more successful for eventual human AD plaque MR imaging, particularly since human AD plaques more closely resemble the cortical and hippocampal plaques of AD transgenic mice than thalamic plaques.

Platelet concentrates produced from whole blood using the Atreus processing system.

BACKGROUND: The Atreus 2C+ system automates whole blood (WB) processing into a red cell concentrate, plasma and buffy coat (BC) suitable for platelet concentrate (PC) manufacture. This study compared the quality of PC made from BC using the Atreus, with those made by a manual method. STUDY DESIGN AND METHODS: WB was collected into Atreus disposables or standard bottom and top processing packs and held without active cooling for 26 h at 22 +/- 2 degrees C before processing, either with the Atreus, or using a centrifuge and press. BC were rested for 3 h and then 4 BC were pooled with one unit of plasma, mixed, centrifuged and pressed to make a pooled PC. The PC were analysed for quality markers to day 9 of storage. RESULTS: Platelet quality was good in both Atreus 2C+ derived PC and control units throughout storage. Metabolic markers (pH, ATP and HSR) and activation markers (CD62P, sCD62P, annexin V binding, microparticles, GP IIb/IIIa) did not differ between the Atreus and control units. Atreus-derived PC had significantly lower platelet yields (302 +/- 59 x 10(9) platelets/unit; mean +/- standard deviation, n = 8) than control PC (411 +/- 76 x 10(9) platelets/unit; P < 0.01), but met the UK guidelines for platelet yield. CONCLUSION: From these in vitro data, PC produced from buffy coats prepared using the Atreus appear suitable for clinical use, and WB may be held at ambient temperature overnight without the use of active cooling devices. Optimizing the secondary processing conditions to handle Atreus 2C+ derived BC may increase the platelet yield.

Feasibility of single-voxel MRS measurement of apparent diffusion coefficient of water in breast tumors.

We report initial results with single voxel spectroscopy (SVS) using diffusion weighting and localization by adiabatic selective refocusing (LASER) in breast tumors to measure the apparent diffusion coefficient of water (ADCw). This is a quick (30 s) and relatively easy method to implement compared with image-based diffusion measurements, and is insensitive to lipid signal contamination. The ADCw and concentration of total choline containing compounds [tCho] were evaluated for associations with each other and final pathologic diagnosis in 25 subjects. The average (+/- SD) ADCw in benign and malignant lesions was 1.96 +/- 0.47 mm(2)/s and 1.26 +/- 0.29 x 10(-3) mm(2)/s, respectively, P< 0.001. Receiver operating characteristic curve analysis showed an area under the curve of 0.92. Analysis of the single voxel (SV) ADCw and [tCho] showed significant correlation with a R(2) of 0.56, P< 0.001. Compared with more commonly used image-based methods of measuring water ADC, SV-ADCw is faster, more robust, insensitive to fat, and potentially easier to implement on standard clinical systems.

Water spin dynamics during apoptotic cell death in glioma gene therapy probed by T1rho and T2rho.

Longitudinal and transverse relaxations in the rotating frame, with characteristic time constants T1rho and T2rho, respectively, have potential to provide unique MRI contrast in vivo. On-resonance spin-lock T1rho with different spin-lock field strengths and adiabatic T2rho with different radiofrequency-modulation functions were measured in BT4C gliomas treated with Herpes Simplex Virus thymidine kinase (HVS-tk) gene therapy causing apoptotic cell death. These NMR tools were able to discriminate different treatment responses in tumor tissue from day 4 onward. An equilibrium two-site exchange model was used to calculate intrinsic parameters describing changes in water dynamics. Observed changes included increased correlation time of water associated with macromolecules and a decreased fractional population of this pool. These results are consistent with destructive intracellular processes associated with cell death and the increase of extracellular space during the treatment. Furthermore, association between longer exchange correlation time and decreased pH during apoptosis is discussed. In this study, we demonstrated that T1rho and T2rho MR imaging are useful tools to quantify early changes in water dynamics reflecting treatment response during gene therapy.

In vitro function of buffy coat-derived platelet concentrates stored for 9 days in CompoSol, PASII or 100% plasma in three different storage bags.

BACKGROUND AND OBJECTIVES: The aim of the study was to compare the in vitro quality of buffy coat-derived platelet concentrates (PC) during extended storage in plasma or additive solution in three different storage bags. MATERIALS AND METHODS: A pooled and split design was chosen so that identical PCs were produced in either 100% plasma, 70% PASII : 30% plasma or 70% CompoSol : 30% plasma (n = 6 each). This was repeated for three different manufacturers' platelet storage bags (Fresenius, Baxter and Pall). PCs were sampled on days 1, 5, 7 and 9 of storage and tested in vitro using a variety of tests of platelet function. For each bag type, storage in PASII or Composol was compared with plasma (data taken across the entire storage period), and differences occurring with time were analysed for all storage media. RESULTS: The pH of all PCs was > 6.8 at day 9 of storage. In vitro platelet function, as assessed by markers of platelet activation and metabolism, of PCs stored in CompoSol appeared to be similar to that of PCs stored in plasma over 9 days of storage. In contrast, PCs stored in PASII tended to have significantly higher levels of platelet activation (almost a twofold increase in % platelets positive for CD62P by day 5) and lower hypotonic shock response (approximately 40%, by day 7) compared to either PCs stored in 100% plasma or 70% CompoSol. The magnitude of the differences observed between platelet storage media appeared to be dependent on the type of platelet storage bag with the highest degree of platelet activation and lowest hypotonic shock response values being observed in Fresenius bags in combination with PASII. CONCLUSIONS: The maintenance of platelet function in vitro during extended storage of PCs in platelet additive solutions is dependent on the combination of type of additive solution and type of platelet storage bag. For all bag types studied, storage in PASII resulted in poorer platelet function in vitro.

Detunable transverse electromagnetic (TEM) volume coil for high-field NMR.

Most high-field MRI systems do not have the actively detuned body coils that are integral to clinical systems operating at 1.5T and lower field strengths. Therefore, many clinical applications requiring homogeneous volume excitation in combination with local surface coil reception are not easily implemented at high fields. To solve this problem for neuroimaging applications, actively detunable transverse electromagnetic (TEM) head coils were developed to be used with receive-only surface coils for signal-to-noise ratio (SNR) gains and improved spatial coverage from homogeneously excited regions. These SNR and field of view (FOV) gains were achieved by application of a detunable TEM volume coil to human brain imaging at 4T.

The return of the frequency sweep: designing adiabatic pulses for contemporary NMR.

Frequency-modulated (FM) pulses that function according to adiabatic principles are becoming increasingly popular in many areas of NMR. Often adiabatic pulses can extend experimental capabilities and minimize annoying experimental imperfections. Here, adiabatic principles and some of the current methods used to create these pulses are considered. The classical adiabatic rapid passage, which is a fundamental element upon which all adiabatic pulses and sequences are based, is analyzed using vector models in different rotating frames of reference. Two methods to optimize adiabaticity are described, and ways to tailor modulation functions to best satisfy specific experimental needs are demonstrated. Finally, adiabatic plane rotation pulses and frequency-selective multiple spin-echo sequences are considered.

7T vs. 4T: RF power, homogeneity, and signal-to-noise comparison in head images.

Signal-to-noise ratio (SNR), RF field (B(1)), and RF power requirement for human head imaging were examined at 7T and 4T magnetic field strengths. The variation in B(1) magnitude was nearly twofold higher at 7T than at 4T ( approximately 42% compared to approximately 23%). The power required for a 90 degrees pulse in the center of the head at 7T was approximately twice that at 4T. The SNR averaged over the brain was at least 1.6 times higher at 7T compared to 4T. These experimental results were consistent with calculations performed using a human head model and Maxwell's equations. Magn Reson Med 46:24-30, 2001.

The effect of leucocyte depletion on the quality of fresh-frozen plasma.

The aim of this study was to evaluate the quality of leucodepleted (LD) fresh-frozen plasma (FFP) produced using one of five whole blood filters (Baxter RS2000 & RZ2000, NPBI T2926, Macopharma LST1 and Terumo WBSP) or two plasma filters (Pall LPS1 and Baxter FGR7014). Whole blood or plasma was filtered within 8 h of collection at an ambient temperature. Samples were taken pre- and post filtration for analysis of coagulation factors and complement activation (n = 7--12 for each type of filter). All filtered units (209--286 ml) contained < 5 x 10(6) residual leucocytes and < 30 x 10(9)/l platelets. Statistically significant losses of factors V, VIII, IX, XI and XII and increases in markers of coagulation activation were observed (0--21%), which were dependent on filter type. None of the filters had a significant effect on von Willebrand factor (VWF) multimeric distribution or the activity of VWF and factors II, VII or X. The effect on levels of C3a appeared to be related to the filter surface charge: positively charged filters resulted in C3a generation, whereas negatively charged resulted in C3a removal. None of the observed changes are likely to be clinically significant unless subsequent processing of plasma (such as pathogen inactivation) results in further losses of coagulation factors.

BISTRO: an outer-volume suppression method that tolerates RF field inhomogeneity.

A technique is described for performing frequency-selective signal suppression with a high degree of tolerance to RF field inhomogeneity. The method is called B1-insensitive train to obliterate signal (BISTRO). BISTRO consists of multiple amplitude- and frequency-modulated (FM) pulses interleaved with spoiler gradients. BISTRO was developed for the purpose of accomplishing band-selective signal removal, as in water suppression and outer-volume suppression (OVS), in applications requiring the use of an inhomogeneous RF transmitter, such as a surface coil. In the present work, Bloch simulations were used to illustrate the principles and theoretical performance of BISTRO. Its performance for OVS was evaluated experimentally using MRI and spectroscopic imaging of phantoms and in vivo animal and human brain. By using FM pulses featuring offset-independent adiabaticity, BISTRO permitted high-quality, broadband suppression with one (or two) discrete borders demarcating the edge(s) of the suppression band. Simulations and experiments demonstrated the ability to operate BISTRO with reasonably attainable peak RF power levels and with average RF energy deposition similar to other multipulse OVS techniques.

Parental sensitivity, infant affect, and affect regulation: predictors of later attachment.

This longitudinal study on 94 families examined the extent to which parent sensitivity, infant affect, and affect regulation at 4 months predicted mother-infant and father-infant attachment classifications at 1 year. Parent sensitivity was rated from face-to-face interaction episodes; infant affect and regulatory behaviors were rated from mother-infant and father-infant still-face episodes at 4 months. Infants' attachment to mothers and fathers was rated from the Strange Situation at 12 and 13 months. MANOVAs indicated that 4-month parent and infant factors were associated with infant-mother but not infant-father attachment groups. Discriminant Function Analysis further indicated that two functions, "Affect Regulation" and "Maternal Sensitivity," discriminated infant-mother attachment groups; As and B1-B2s showed more affect regulation toward mothers and fathers than B3-B4s and Cs at 4 months, and mothers of both secure groups were more sensitive than mothers of Cs. Finally, the association between maternal sensitivity and infant-mother attachment was partially mediated by infant affect regulation.

Identifying the psychological needs of foster children.

Recent research has pointed to the increased risk of pathology for children placed in foster care. In response, the Child Welfare League of America has advocated for routine assessment of the psychological needs of children in foster care. A model for standardized psychological screening for all foster children shortly after placement is described. Interdisciplinary relationships between medical and psychological staff are stressed. Typical referral questions are outlined and suggestions for a testing battery that covers cognitive, behavioral, and emotional realms are given. Issues and problems inherent in testing this population are discussed, but the importance of psychological screening of this at-risk population is emphasized.

Applications of magnetic resonance in model systems: tumor biology and physiology.

A solid tumor presents a unique challenge as a system in which the dynamics of the relationship between vascularization, the physiological environment and metabolism are continually changing with growth and following treatment. Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) studies have demonstrated quantifiable linkages between the physiological environment, angiogenesis, vascularization and metabolism of tumors. The dynamics between these parameters continually change with tumor aggressiveness, tumor growth and during therapy and each of these can be monitored longitudinally, quantitatively and non-invasively with MRI and MRS. An important aspect of MRI and MRS studies is that techniques and findings are easily translated between systems. Hence, pre-clinical studies using cultured cells or experimental animals have a high connectivity to potential clinical utility. In the following review, leaders in the field of MR studies of basic tumor physiology using pre-clinical models have contributed individual sections according to their expertise and outlook. The following review is a cogent and timely overview of the current capabilities and state-of-the-art of MRI and MRS as applied to experimental cancers. A companion review deals with the application of MR methods to anticancer therapy.

Subchronic in vivo effects of a high static magnetic field (9.4 T) in rats.

The potential adverse biologic effects of sub chronic (cumulatively 10 weeks) exposure to a high magnetic field (9.4 T) were evaluated in young adult male and female Fischer rats as well as in their progeny. Biologic end points in adult rats included changes in daily clinical observations; spatial memory tests; weekly heart rates, body weights, food and water consumption, and the feed efficiency ratio; terminal hematologic, blood biochemical and urinary parameter changes; gross pathologic findings; and major organ weights. In offspring, biologic end points included the gestation period, number of live births, number of pups, ratio of male to female pups/litter; postnatal time period of eye opening; birth and weekly body weights, behavioral changes, central nervous system responses, as well as hematologic, blood biochemistry, and urinary parameter changes; and gross pathologic findings. Findings from this study showed that there were no adverse biologic effects in male and female adult rats or their progeny that could be attributed to 10-week exposure to a 9.4-T static magnetic field.

Imaging blood flow in brain tumors using arterial spin labeling.

Measurements of tumor blood flow (TBF) are important for understanding tumor physiology and can be valuable in selecting and evaluating therapies. Brain tumors typically present reduced blood flows compared to normal brain tissue. This study shows that the arterial spin labeling (ASL) technique can be used to measure TBF non-invasively in a rat glioma model. Results show that TBF in the core (36.3 +/- 18.9 ml/100g/min, n=4) and peripheral regions (85.3 +/- 26.9 ml/100g/min, n=4) of the tumor are significantly reduced and show considerable heterogeneity compared to cerebral blood flow (CBF) of normal brain tissue (147.7 +/- 31.1 ml/100g/min, n=4), while T(1) in the tumor (2.6 +/- 0.1 sec) is significantly elevated compared to normal tissue T(1) (2.0 +/- 0.0 sec). These results strongly support the feasibility of using the ASL technique to evaluate different cancer treatment strategies, to monitor the effects of agents designed to modulate TBF and oxygenation (e.g., carbogen gas), and to assess and guide the use of anti-angiogenic agents. Magn Reson Med 44:169-173, 2000.