The relevance of hippocampal subfield integrity and clock drawing test performance for the diagnosis of Alzheimer's disease and mild cognitive impairment

OBJECTIVES

The clock drawing test (CDT) is one of the worldwide most used screening tests for Alzheimer's disease (AD). MRI studies have identified temporo-parietal regions being involved in CDT impairment. However, the contributions of specific hippocampal subfields and adjacent extrahippocampal structures to CDT performance in AD and mild cognitive impairment (MCI) have not been investigated so far. It is unclear whether morphological alterations or CDT score, or a combination of both, are able to predict AD.

METHODS

38 AD patients, 38 MCI individuals and 31 healthy controls underwent neuropsychological assessment and MRI at 3 Tesla. FreeSurfer 5.3 was used to perform hippocampal parcellation. We used a collection of statistical methods to better understand the relationship between CDT and hippocampal formation. We also tested the clinical feasibility of this relationship when predicting AD.

RESULTS

Impaired CDT performance in AD was associated with widespread atrophy of the cornu ammonis, presubiculum, and subiculum, whereas MCI subjects showed CDT-related alterations of the CA4-dentate gyrus and subiculum. CDT correlates in AD and MCI showed regional and quantitative overlap. Importantly, CDT score was the best predictor of AD.

CONCLUSIONS

Our findings lend support for an involvement of different hippocampal subfields in impaired CDT performance in AD and MCI. CDT seems to be more efficient than subfield imaging for predicting AD.

On using Rayleigh scattering for in situ spectral calibration of Thomson scattering diagnostics

A new method for in situ spectral calibration of Thomson scattering diagnostics is proposed. The idea of the method is to apply a wavelength tunable optical parametric oscillator for measurements of Rayleigh scattering at different wavelengths, from which relative sensitivities can be calculated. This extends the usual approach where Rayleigh scattering is used only at a single wavelength for the absolute calibration and spectral sensitivities are obtained separately. With the new approach, the full diagnostic setup is spectrally calibrated at once. Such a calibration can be repeated at regular intervals during an experimental campaign since it does not require a break of the vacuum. In this paper, the Rayleigh scattering calibration is tested in a laboratory setup with a sample Wendelstein 7-X (W7-X) polychromator. It is shown that relative sensitivities of spectral channels can be recovered with a sufficient resolution even under conditions of significant stray light. The stray light is overcome by measuring the linear dependence of the scattered signal on the gas pressure. Good results of laboratory tests motivate the installation of the new calibration system for the Thomson scattering diagnostic at W7-X.

Aberrant cortical neurodevelopment in major depressive disorder

BACKGROUND

There is strong neuroimaging evidence that cortical alterations represent a core pathophysiological feature of major depressive disorder (MDD). Differential contributions of cortical features of neurodevelopmental origin, which may distinctly contribute to MDD vulnerability, disease-onset, or symptom expression, are unclear at present.

METHODS

We investigated distinct markers of cortical neurodevelopment, i.e. local cortical gyrification (LGI) and thickness (CT) in patients with MDD (n = 38) and healthy controls (HC, n = 22) using 3 T structural magnetic resonance imaging data and surface-based data analysis techniques. CT and LGI were computed using the Computational Anatomy Toolbox (CAT12). Analyses were performed for the entire cortical surface followed by a complementary regions-of-interest approach.

RESULTS

MDD patients showed significantly greater LGI in frontal, cingulate, parietal, temporal, and occipital regions compared to HC (FDR-corrected at p < 0.05 using threshold-free cluster enhancement). No significant differences of CT were found. In the MDD-group, correlations were found between duration of illness in years and number of depressive episodes and LGI of frontal, temporal, and parietal regions (p < 0.05).

LIMITATIONS

Main limitations are the relatively modest sample size and a cross-sectional study design. We did not control for early environmental factors potentially influencing neurodevelopment, such as childhood trauma. We report associations uncorrected for multiple comparisons.

CONCLUSIONS

The data suggest different local trajectories of cortical change in MDD. In addition, our data support the notion that aberrant cortical development may serve as a vulnerability marker of MDD, as well as a potential predictor of disease course.

Investigation of Optically Grey Electron Cyclotron Harmonics in Wendelstein 7-X

For a magnetic field of 2.5T, the electron cyclotron harmonics are spectrally well separated in W7-X as it has a large aspect ratio. Because of this advantage from the geometry of W7-X stellarator, it is easier to scan these higher harmonics (70,140,210…..GHz) compared to tokamaks with small aspect ratio. For confinement reasons, W7-X is planned to work at high plasma densities applying O2 electron cyclotron resonance heating (ECRH). For such plasmas, which already have been demonstrated in experimental campaign OP1.2a of W7-X, electron cyclotron emission (ECE) from second harmonic extraordinary mode (X2) is in cutoff. In that case, optically grey higher harmonics provide the only access to ECE signal and hence electron temperature profiles. A Michelson interferometer will be used in the next operational campaign of W7-X for broadband (50-500 GHz) ECE scan and that will be compared to modeling of ECE emission at different plasma parameters from radiation transport calculations (TRAVIS). The strong stray radiation from non-absorbed ECRH is a major concern in scanning these higher harmonics using an interferometer because this stray radiation will dominate the spectra thus masking the ECE signal. For this purpose, a multimode notch filter design based on a multilayer dielectric structure is constructed to attenuate the stray radiation at 140GHz by 50dB.

Collective Thomson scattering diagnostic at Wendelstein 7-X

A Collective Thomson Scattering (CTS) diagnostic is installed at Wendelstein 7-X for ion temperature measurements in the plasma core. The diagnostic utilizes 140 GHz gyrotrons usually used for electron cyclotron resonance heating (ECRH) as a source of probing radiation. The CTS diagnostic uses a quasi-optical transmission line covering a distance of over 40 m. The transmission line is shared between the ECRH system and the CTS diagnostic. Here we elaborate on the design, installation, and alignment of the CTS diagnostic and present the first measurements at Wendelstein 7-X.

Prospects of X-ray imaging spectrometers for impurity transport: Recent results from the stellarator Wendelstein 7-X (invited)

This paper reports on the design and the performance of the recently upgraded X-ray imaging spectrometer systems, X-ray imaging crystal spectrometer and high resolution X-ray imaging spectrometer, installed at the optimized stellarator Wendelstein 7-X. High resolution spectra of highly ionized, He-like Si, Ar, Ti, and Fe as well as H-like Ar have been observed. A cross comparison of ion and electron temperature profiles derived from a spectral fit and tomographic inversion of Ar and Fe spectra shows a reasonable match with both the spectrometers. The also measured impurity density profiles of Ar and Fe have peaked densities at radial positions that are in qualitative agreement with the expectations from the He-like impurity fractional abundances, given the measured temperature profiles. Repeated measurements of impurity decay times have been demonstrated with an accuracy of 1 ms via injection of non-recycling Ti, Fe, and Mo impurities using a laser blow-off system.

Motor dysfunction as an intermediate phenotype across schizophrenia and other psychotic disorders: Progress and perspectives

Primary motor abnormalities (PMA), as found in patients with schizophrenia, are quantitatively and qualitatively distinct markers of motor system abnormalities. PMA have been often referred to phenomena that are present across schizophrenia-spectrum disorders. A dysfunction of frontoparietal and subcortical networks has been proposed as core pathophysiological mechanism underlying the expression of PMA. However, it is unclear at present if such mechanisms are a common within schizophrenia and other psychotic disorders. To address this question, we review recent neuroimaging studies investigating the neural substrates of PMA in schizophrenia and so-called "nonschizophrenic nonaffective psychoses" (NSNAP) such as schizophreniform, schizoaffective, brief psychotic, and other unspecified psychotic disorders. Although the extant data in patients with schizophrenia suggests that further investigation is warranted, MRI findings in NSNAP are less persuasive. It is unclear so far which PMA, if any, are characteristic features of NSNAP or, possibly even specific for these disorders. Preliminary data suggest a relationship between relapsing-remitting PMA in hyper-/hypokinetic cycloid syndromes and neurodegenerative disorders of the basal ganglia, likely reflecting the transnosological relevance of subcortical abnormalities. Despite this evidence, neural substrates and mechanisms underlying PMA that are common in schizophrenia and NSNAP cannot be clearly delineated at this stage of research. PMA and their underlying brain circuits could be promising intermediate phenotype candidates for psychotic disorders, but future multimodal neuroimaging studies in schizophrenia and NSNAP patients and their unaffected first-degree relatives are needed to answer fundamental transnosologic questions.

Common and distinct patterns of abnormal cortical gyrification in major depression and borderline personality disorder

Abnormal gray matter volume has been consistently reported in patients with major depressive disorder (MDD), but markers of cortical neurodevelopment have been rarely investigated. Also, it is unclear whether there exist common versus distinct spatial patterns of abnormal cortical development across different disorders presenting with negative emotions and deficient affective regulation. In this study, we used structural MRI at 3T to investigate the local gyrification index (LGI), a marker of fetal/infant neurodevelopment, in adult female patients with MDD (n = 22), in adult female patients with borderline personality disorder (BPD) (n = 17), and in controls (n = 22). Reduced cortical folding of the precuneus, the superior parietal gyrus and the parahippocampal gyrus was found in both MDD and BPD patients when compared to controls (p < 0.05, cluster-wise probability [CWP] corrected). MDD patients showed additional hypogyrification of the middle frontal gyrus and the fusiform gyrus when compared to both controls and BPD patients (p < 0.05, CWP corrected). In MDD patients, lower LGI of prefrontal regions was significantly associated with the age of disease onset and with the number of depressive episodes. In BPD patients, lower LGI of orbitofrontal regions was associated with impulsivity. Our findings suggest abnormal early cortical development in MDD, affecting brain regions that have been frequently implied in MDD pathophysiology. However, LGI abnormalities may not be specific for MDD, since MDD and BPD patients also exhibited common patterns of hypogyrification. Hypogyrification of cortical regions associated with higher-order cognition appears to be most pronounced in MDD. Abnormal early cortical neurodevelopment may mediate vulnerability to disorders of emotion.

Dual-laser wavelength Thomson scattering at Wendelstein 7-X

This paper presents the approach of the dual-laser wavelength Thomson scattering (TS) system for the Wendelstein 7-X stellarator. The dual-laser wavelength TS method is based on two lasers with different wavelengths being fired quasi-simultaneously. This method has two advantages compared to a single laser wavelength TS system. First, the dual laser availability allows an in situ spectral calibration, and second, higher electron temperatures can be measured without any change in the spectral filter setup of the polychromators. The W7-X dual-laser wavelength TS concept is based on high power lasers: a set of standard Nd:YAG lasers with λ = 1064 nm wavelength and a Nd:YAG laser with λ = 1319 nm wavelength newly developed for this application. This laser uses a different transition line with 34% efficiency compared to the main 1064 nm Nd:YAG line. Simulations of the expected performance of the new dual-laser wavelength system show that electron temperatures up to T_e = 15 keV can be measured compared to the original design parameter up to Te = 10 keV. The in situ spectral calibration can be performed using a range of temperatures from 1 keV to 10 keV using TS measurements of the 1064 nm versus 1319 nm TS simultaneously.

Bayesian uncertainty calculation in neural network inference of ion and electron temperature profiles at W7-X

We make use of a Bayesian description of the neural network (NN) training for the calculation of the uncertainties in the NN prediction. Having uncertainties on the NN prediction allows having a quantitative measure for trusting the NN outcome and comparing it with other methods. Within the Bayesian framework, the uncertainties can be calculated under different approximations. The NN has been trained with the purpose of inferring ion and electron temperature profile from measurements of a X-ray imaging diagnostic at W7-X. The NN has been trained in such a way that it constitutes an approximation of a full Bayesian model of the diagnostic, implemented within the Minerva framework. The network has been evaluated using measured data and the uncertainties calculated under different approximations have been compared with each other, finding that neglecting the noise on the NN input can lead to an underestimation of the error bar magnitude in the range of 10%-30%.

Motor dysfunction as research domain across bipolar, obsessive-compulsive and neurodevelopmental disorders

Although genuine motor abnormalities (GMA) are frequently found in schizophrenia, they are also considered as an intrinsic feature of bipolar, obsessive-compulsive, and neurodevelopmental disorders with early onset such as autism, ADHD, and Tourette syndrome. Such transnosological observations strongly suggest a common neural pathophysiology. This systematic review highlights the evidence on GMA and their neuroanatomical substrates in bipolar, obsessive-compulsive, and neurodevelopmental disorders. The data lends support for a common pattern contributing to GMA expression in these diseases that seems to be related to cerebello-thalamo-cortical, fronto-parietal, and cortico-subcortical motor circuit dysfunction. The identified studies provide first evidence for a motor network dysfunction as a correlate of early neurodevelopmental deviance prior to clinical symptom expression. There are also first hints for a developmental risk factor model of these mental disorders. An in-depth analysis of motor networks and related patho-(physiological) mechanisms will not only help promoting Research Domain Criteria (RDoC) Motor System construct, but also facilitate the development of novel psychopharmacological models, as well as the identification of neurobiologically plausible target sites for non-invasive brain stimulation.

Comparable outcomes using propylene glycol-free melphalan for autologous stem cell transplantation in multiple myeloma

Autologous stem cell transplantation (ASCT) remains a mainstay in the treatment of multiple myeloma (MM). While the procedure is generally safe, toxicities associated with high-dose melphalan conditioning are common and significantly affect patient quality of life. Recently, a propylene glycol-free melphalan formulation (PG-free MEL; Evomela^®) was approved by the United States Food and Drug Administration as an ASCT conditioning regimen for MM. PG-free MEL is more soluble and stable than propylene glycol-solubilized melphalan (PG-solubilized MEL; Alkeran^®). As such, there is speculation that it could decrease toxicities and increase the efficacy of ASCT. We compared the outcomes of patients conditioned with PG-free MEL (n=216) to PG-solubilized MEL (n=200) at our institution. The baseline characteristics were similar between the two groups. After Day +0, there were no differences in terms of hospitalizations, neutropenic fevers, intravenous granisetron requirement, World Health Organization grade ≥2 oral/esophageal mucositis, intravenous fluid requirement, or narcotic requirement. However, PG-free MEL patients had a higher incidence of diarrhea, which was mostly C. difficile-negative (82% vs. 71%, P=0.015*). Day +100 hematologic responses and progression-free survival after ASCT were comparable. In summary, we demonstrate that switching to PG-free MEL did not significantly reduce short-term complications of ASCT or improve outcomes in MM.

Cerebellar Contributions to Major Depression

Extending beyond the motor domain, the cerebellum is involved in various aspects of cognition and affect. Multidisciplinary evidence has demonstrated topographic organization of higher-order cognitive functions within the cerebellum. We here review recent neuroimaging research that indicates cerebellar contributions to major depressive disorder (MDD). At the structural level, increased volume of lobule IX has been demonstrated in MDD patients, independent of acute or remitted disease state. Successful treatment with electroconvulsive therapy has been associated with increased lobule VIIA volume in depressed patients. At the functional level, connectivity analyses have shown reduced cerebro-cerebellar coupling of lobules VI and VIIA/B with prefrontal, posterior parietal, and limbic regions in patients with MDD. As a limitation, most of this evidence is based on smaller patient samples with incomplete phenotypic and neuropsychological characterization and with heterogenous medication. Some studies did not apply cerebellum-optimized data analysis protocols. Taken together, MDD pathophysiology affects distinct subregions of the cerebellum that communicate with cortical networks subserving cognitive and self-referential processing. This mini-review synthesizes research evidence from cerebellar structural and functional neuroimaging in depression, and provides future perspectives for neuroimaging of cerebellar contributions to MDD.

Intrinsic neural network dysfunction in quiescent Crohn's Disease

Psychological factors and comorbidities play an important role in inflammatory bowel diseases. Such comorbidity could be associated with a specific neural phenotype. Brain regions associated with emotion regulation and self-referential processing, including areas assigned to the “default mode network” (DMN), could be promising candidates in this regard. We investigated the functional integrity of multiple intrinsic neural networks in remitted patients with Crohn’s disease (CD) and sought to establish relationships between neural network connectivity and psychiatric symptoms. Fifteen CD patients in remission and 14 controls were investigated. We employed resting-state functional magnetic resonance imaging (fMRI) at 3 Tesla followed by a spatial Independent Component Analysis for fMRI data. Abnormal connectivity in CD patients was observed in DMN subsystems only (p < 0.05, cluster-corrected). Increased connectivity was found in the anterior cingulate and left superior medial frontal gyrus (aDMN) and the middle cingulate cortex (pDMN). Middle cingulate activity showed a significant association with anxiety scores in patients (p = 0.029). This study provides first evidence of selectively disrupted intrinsic neural network connectivity in CD and suggests abnormalities of self-referential neural networks. An increased sensitivity to self-related affective and somatic states in CD patients could account for these findings and explain a higher risk for anxiety symptoms.

Cortical signature of clock drawing performance in Alzheimer's disease and mild cognitive impairment

It is unclear whether clock drawing test (CDT) performance relies on a widely distributed cortical network, or whether this test predominantly taps into parietal cortex function. So far, associations between cortical integrity and CDT impairment in Alzheimer's disease (AD) and mild cognitive impairment (MCI) largely stem from cortical volume analyses. Given that volume is a product of thickness and surface area, investigation of the relationship between CDT and these two cortical measures might contribute to better understanding of this cognitive screening tool for AD. 38 patients with AD, 38 individuals with MCI and 31 healthy controls (HC) underwent CDT assessment and MRI at 3 Tesla. The surface-based analysis via Freesurfer enabled calculation of cortical thickness and surface area. CDT was scored according to the method proposed by Shulman and related to the two distinct cortical measurements. Higher CDT scores across the entire sample were associated with cortical thickness in bilateral temporal gyrus, the right supramarginal gyrus, and the bilateral parietal gyrus, respectively (p < 0.001 CWP corr.). Significant associations between CDT and cortical thickness reduction in the parietal lobe remained significant when analyses were restricted to AD individuals. There was no statistically significant association between CDT scores and surface area (p < 0.001 CWP corr.). In conclusion, CDT performance may be driven by cortical thickness alterations in regions previously identified as "AD vulnerable", i.e. regions predominantly including temporal and parietal lobes. Our results suggest that cortical features of distinct evolutionary and genetic origin differently contribute to CDT performance.

Cortical features of distinct developmental trajectories in patients with delusional infestation

BACKGROUND

Although there is strong neuroimaging evidence that cortical alterations are a core feature of schizophrenia spectrum disorders, it still remains unclear to what extent such abnormalities occur in monothematic delusional disorders. In individuals with delusional infestation (DI), the delusional belief to be infested with pathogens, previous structural MRI studies have shown prefrontal, temporal, parietal, insular, thalamic and striatal gray matter volume changes. Differential contributions of cortical features of evolutionary and genetic origin (such as cortical thickness, area and folding) which may distinctly contribute to DI pathophysiology are unclear at present.

METHODS

In this study, 18 patients with DI and 20 healthy controls (HC) underwent MRI scanning at 1.0T. Using surface-based analyses we calculated cortical thickness, surface area and local gyrification index (LGI). Whole-brain differences between patients and controls were investigated.

RESULTS

Surface analyses revealed frontoparietal patterns exhibiting altered cortical thickness, surface area and LGI in DI patients compared to controls. Higher cortical thickness was found in the right medial orbitofrontal cortex (p<0.05, cluster-wise probability [CWP] corrected). Smaller surface area in patients was found in the left inferior temporal gyrus, the precuneus, the pars orbitalis of the right frontal gyrus, and the lingual gyrus (p<0.05, CWP corr.). Lower LGI was found in the left postcentral, bilateral precentral, right middle temporal, inferior parietal, and superior parietal gyri (p<0.01, CWP corr.).

CONCLUSION

This study lends further support to the hypothesis that cortical features of distinct evolutionary and genetic origin differently contribute to the pathogenesis of delusional disorders. Regions in which atrophy was observed are part of neural circuits associated with perception, visuospatial control and self-awareness. The data are in line with the notion of a content-specific neural signature of DI.

White matter microstructure variations contribute to neurological soft signs in healthy adults

OBJECTIVE

Neurological soft signs (NSS) are core features of psychiatric disorders with significant neurodevelopmental origin. However, it is unclear whether NSS correlates are associated with neuropathological processes underlying the disease or if they are confounded by medication. Given that NSS are also present in healthy persons (HP), investigating HP could reveal NSS correlates, which are not biased by disease-specific processes or drug treatment. Therefore, we used a combination of diffusion MRI analysis tools to provide a framework of specific white matter (WM) microstructure variations underlying NSS in HP.

METHOD

NSS of 59 HP were examined on the Heidelberg Scale and related to diffusion associated metrics. Using tract-based spatial statistics (TBSS), we studied WM variations in fractional anisotropy (FA) as well as radial (RD), axial (AD), and mean diffusivity (MD). Using graph analytics (clustering coefficient-CC, local betweenness centrality -BC), we then explored DTI-derived structural network variations in regions identified by previous MRI studies on NSS.

RESULTS

NSS scores were negatively associated with RD, AD and MD in corpus callosum, brainstem and cerebellum (P < 0.05, corr.). NSS scores were negatively associated with CC and BC of the pallidum, the superior parietal gyrus, the precentral sulcus, the insula, and the cingulate gyrus (P < 0.05, uncorr.).

CONCLUSION

The present study supports the notion that WM microstructure variations in subcortical and cortical sensorimotor regions contribute to NSS expression in young HP. Hum Brain Mapp 38:3552-3565, 2017. © 2017 Wiley Periodicals, Inc.

Hippocampal formation alterations differently contribute to autobiographic memory deficits in mild cognitive impairment and Alzheimer's disease

Autobiographical memory (AM) is part of declarative memory and includes both semantic and episodic aspects. AM deficits are among the major complaints of patients with Alzheimer's disease (AD) even in early or preclinical stages. Previous MRI studies in AD patients have showed that deficits in semantic and episodic AM are associated with hippocampal alterations. However, the question which specific hippocampal subfields and adjacent extrahippocampal structures contribute to deficits of AM in individuals with mild cognitive impairment (MCI) and AD patients has not been investigated so far. Hundred and seven participants (38 AD patients, 38 MCI individuals and 31 healthy controls [HC]) underwent MRI at 3 Tesla. AM was assessed with a semi-structured interview (E-AGI). FreeSurfer 5.3 was used for hippocampal parcellation. Semantic and episodic AM scores were related to the volume of 5 hippocampal subfields and cortical thickness in the parahippocampal and entorhinal cortex. Both semantic and episodic AM deficits were associated with bilateral hippocampal alterations. These associations referred mainly to CA1, CA2-3, presubiculum, and subiculum atrophy. Episodic, but not semantic AM loss was associated with cortical thickness reduction of the bilateral parahippocampal and enthorinal cortex. In MCI individuals, episodic, but not semantic AM deficits were associated with alterations of the CA1, presubiculum and subiculum. Our findings support the crucial role of CA1, presubiculum, and subiculum in episodic memory. The present results implicate that in MCI individuals, semantic and episodic AM deficits are subserved by distinct neuronal systems.

The Thomson scattering system at Wendelstein 7-X

This paper describes the design of the Thomson scattering system at the Wendelstein 7-X stellarator. For the first operation campaign we installed a 10 spatial channel system to cover a radial half profile of the plasma cross section. The start-up system is based on one Nd:YAG laser with 10 Hz repetition frequency, one observation optics, five fiber bundles with one delay line each, and five interference filter polychromators with five spectral channels and silicon avalanche diodes as detectors. High dynamic range analog to digital converters with 14 bit, 1 GS/s are used to digitize the signals. The spectral calibration of the system was done using a pulsed super continuum laser together with a monochromator. For density calibration we used Raman scattering in nitrogen gas. Peaked temperature profiles and flat density profiles are observed in helium and hydrogen discharges.

Imaging motional Stark effect measurements at ASDEX Upgrade

This paper presents an overview of results from the Imaging Motional Stark Effect (IMSE) diagnostic obtained during its first measurement campaign at ASDEX Upgrade since installation as a permanent diagnostic. A brief overview of the IMSE technique is given, followed by measurements of a standard H-mode discharge, which are compared to equilibrium reconstructions showing good agreement where expected. The development of special discharges for the calibration of pitch angle is reported and safety factor profile changes during sawteeth crashes are shown, which can be resolved to a few percent due to the high sensitivity at good time resolution of the new IMSE system.

Fludarabine-Busulfan Reduced-Intensity Conditioning in Comparison with Fludarabine-Melphalan Is Associated with Increased Relapse Risk In Spite of Pharmacokinetic Dosing

Fludarabine with busulfan (FB) and fludarabine with melphalan (FM) are commonly used reduced-intensity conditioning (RIC) regimens. Pharmacokinetic dosing of busulfan (Bu) is frequently done for myeloablative conditioning, but evidence for its use is limited in RIC transplants. We compared transplant outcomes of FB versus FM using i.v. Bu targeted to the area under the curve (AUC). A total of 134 RIC transplants (47 FB and 87 FM) for acute myelogenous leukemia and myelodysplastic syndrome were identified, and median follow-up of the cohort was 40 months (range, 0 to 63.3). A significantly higher 2-year cumulative incidence of relapse (CIR) was associated with FB versus FM at 35.6% versus 17.3%, respectively (P = .0058). Furthermore, 2-year progression-free survival rates were higher for FM versus FB at 60.5% versus 48.7%, respectively (P = .04). However, 2-year rates of nonrelapse mortality (NRM) and overall survival (OS) were similar. The need for dose adjustment based on AUC did not alter relapse risk or NRM. Patients with Karnofsky performance status ≥ 90 who received FM had a 2-year OS rate of 74.8% versus 48.3% for FB (P = .03). FB use remained prognostic for relapse in multivariable analysis (hazard ratio, 2.75; 95% confidence interval, 1.28 to 5.89; P = .0097). In summary, in spite of AUC-directed dosing, FB compared with FM was associated with a significantly higher CIR.