Methotrexate (MTX) can cause significant clinical neurotoxicity and asymptomatic leukoencephalopathy. We sought to identify clinical, pharmacokinetic, and genetic risk factors for these MTX-related ...toxicities during childhood acute lymphoblastic leukemia (ALL) therapy and provide data on safety of intrathecal and high-dose MTX rechallenge in patients with neurotoxicity.
Prospective brain magnetic resonance imaging was performed at four time points for 369 children with ALL treated in a contemporary study that included five courses of high-dose MTX and 13 to 25 doses of triple intrathecal therapy. Logistic regression modeling was used to evaluate clinical and pharmacokinetic factors, and a genome-wide association study (GWAS) was performed to identify germline polymorphisms for their association with neurotoxicities.
Fourteen patients (3.8%) developed MTX-related clinical neurotoxicity. Of 13 patients rechallenged with intrathecal and/or high-dose MTX, 12 did not experience recurrence of neurotoxicity. Leukoencephalopathy was found in 73 (20.6%) of 355 asymptomatic patients and in all symptomatic patients and persisted in 74% of asymptomatic and 58% of symptomatic patients at the end of therapy. A high 42-hour plasma MTX to leucovorin ratio (measure of MTX exposure) was associated with increased risk of leukoencephalopathy in multivariable analysis (P = .038). GWAS revealed polymorphisms in genes enriched for neurodevelopmental pathways with plausible mechanistic roles in neurotoxicity.
MTX-related clinical neurotoxicity is transient, and most patients can receive subsequent MTX without recurrence of acute or subacute symptoms. All symptomatic patients and one in five asymptomatic patients develop leukoencephalopathy that can persist until the end of therapy. Polymorphisms in genes related to neurogenesis may contribute to susceptibility to MTX-related neurotoxicity.
Microstructural asymmetry of the brain can provide more direct causal explanations of functional lateralization than can macrostructural asymmetry. We performed a cross-sectional diffusion imaging ...study of 314 patients treated for childhood acute lymphoblastic leukemia (ALL) at a single institution and 92 healthy controls. An asymmetry index based on diffusion metrics was computed to quantify brain microstructural asymmetry. The effects of age and the asymmetry metrics of the two cohorts were examined with t-tests and linear models. We discovered two new types of microstructural asymmetry. Myelin-related asymmetry in controls was prominent in the back brain (89% right), whereas axon-related asymmetry occurred in the front brain (67% left) and back brain (88% right). These asymmetries indicate that white matter is more mature and more myelinated in the left back brain, potentially explaining the leftward lateralization of language and visual functions. The asymmetries increase throughout childhood and adolescence (P = 0.04) but were significantly less in patients treated for ALL (P<0.01), especially in younger patients. Our results indicate that atypical brain development may appear long before patients treated with chemotherapy become symptomatic.
To examine associations among methotrexate pharmacodynamics, neuroimaging, and neurocognitive outcomes in long-term survivors of childhood acute lymphoblastic leukemia treated on a contemporary ...chemotherapy-only protocol.
This longitudinal study linked pharmacokinetic assays collected during therapy to neurocognitive and brain imaging outcomes during long-term follow-up. A total of 218 (72.2%) of 302 eligible long-term survivors were recruited for outcome studies when they were more than 5 years post-diagnosis and older than 8 years of age. At long-term follow-up, survivors were an average of 13.8 years old and 7.7 years from diagnosis, and 51% were male. Neurocognitive testing, functional magnetic resonance imaging (MRI) during an executive function task, and structural MRI with diffusion tensor imaging were conducted. Generalized linear models were developed to identify predictors, and models were adjusted for age at diagnosis, sex, and parent education.
Intelligence was within normal limits (mean, 98; standard deviation, 14) compared with population expectations (mean, 100; standard deviation, 15), though measures of executive function, processing speed, and memory were less than population means (all P < .02 after correction for false discovery rates). Higher plasma concentration of methotrexate was associated with a poorer executive function score (P < .02). Higher plasma methotrexate was also associated with higher functional MRI activity, with thicker cortices in dorsolateral prefrontal brain regions, and with white matter microstructure in the frontostriatal tact. Neurocognitive impairment was associated with these imaging findings as well. Associations did not change after adjustment for age or dose of leucovorin rescue.
Survivors of childhood acute lymphoblastic leukemia treated on contemporary chemotherapy-only protocols demonstrate executive dysfunction. A higher plasma concentration of methotrexate was associated with executive dysfunction as well as with a thicker cortex and higher activity in frontal brain regions, regions often associated with executive function.
Recent innovations in quantitative magnetic resonance imaging (MRI) measurement methods have led to improvements in accuracy, repeatability, and acquisition speed, and have prompted renewed interest ...to reevaluate the medical value of quantitative T1. The purpose of this study was to determine the bias and reproducibility of T1 measurements in a variety of MRI systems with an eye toward assessing the feasibility of applying diagnostic threshold T1 measurement across multiple clinical sites. We used the International Society of Magnetic Resonance in Medicine/National Institute of Standards and Technology (ISMRM/NIST) system phantom to assess variations of T1 measurements, using a slow, reference standard inversion recovery sequence and a rapid, commonly-available variable flip angle sequence, across MRI systems at 1.5 tesla (T) (two vendors, with number of MRI systems n = 9) and 3 T (three vendors, n = 18). We compared the T1 measurements from inversion recovery and variable flip angle scans to ISMRM/NIST phantom reference values using Analysis of Variance (ANOVA) to test for statistical differences between T1 measurements grouped according to MRI scanner manufacturers and/or static field strengths. The inversion recovery method had minor over- and under-estimations compared to the NMR-measured T1 values at both 1.5 T and 3 T. Variable flip angle measurements had substantially greater deviations from the NMR-measured T1 values than the inversion recovery measurements. At 3 T, the measured variable flip angle T1 for one vendor is significantly different than the other two vendors for most of the samples throughout the clinically relevant range of T1. There was no consistent pattern of discrepancy between vendors. We suggest establishing rigorous quality control procedures for validating quantitative MRI methods to promote confidence and stability in associated measurement techniques and to enable translation of diagnostic threshold from the research center to the entire clinical community.
Survivors of childhood acute lymphoblastic leukemia (ALL) treated with CNS-directed chemotherapy are at risk for neurocognitive deficits. Prospective longitudinal studies are needed to clarify the ...neurodevelopmental trajectory in this vulnerable population.
Patients enrolled in the St. Jude Total Therapy Study XV, which omitted prophylactic cranial radiation therapy in all patients, completed comprehensive neuropsychological assessments at induction (n = 142), end of maintenance (n = 243), and 2 years after completion of therapy (n = 211). We report on longitudinal change in neurocognitive function and predictors of neurocognitive outcomes 2 years after completing therapy.
Neurocognitive function was largely age appropriate 2 years after completing therapy; however, the overall group demonstrated significant attention deficits and a significantly greater frequency of learning problems as compared with national normative data (all P ≤ .005). Higher-intensity CNS-directed chemotherapy conferred elevated risk for difficulties in attention, processing speed, and academics (all P ≤ .01). The rate and direction of change in performance and caregiver-reported attention difficulties differed significantly by age at diagnosis and sex. End-of-therapy attention problems predicted lower academic scores 2 years later, with small to moderate effect sizes (│r│= 0.17 to 0.25, all P ≤ .05).
Two years after chemotherapy-only treatment, neurocognitive function is largely age appropriate. Nonetheless, survivors remain at elevated risk for attention problems that impact real-world functioning. Attention problems at the end of therapy predicted decreased academics 2 years later, suggesting an amplified functional impact of discrete neurocognitive difficulties. Age at diagnosis and patient sex may alter neurocognitive development in survivors of childhood ALL treated with chemotherapy-only protocols.
Background
In archived diffusion tensor imaging (DTI) studies, a reversed‐phase encoding (PE) scan required to correct the distortion in single‐shot echo‐planar imaging (EPI) may not have been ...acquired. Furthermore, DTI tractography is adversely affected by incorrect white matter segmentation due to leukoencephalopathy (LE). All these issues need to be addressed.
Purpose
To propose and evaluate a modified DTI processing pipeline with DIstortion COrrection using pseudo T2‐weighted images (DICOT) to overcome limitations in existing acquisition protocols.
Study Type
Retrospective feasibility.
Subjects
DICOT was assessed in simulated data and 84 acute lymphoblastic leukemia (ALL) patients with reversed PE acquired. The pipeline was then tested in 522 scans from 261 ALL patients without a reversed PE acquired.
Field Strength/Sequence
A 3 T; diffusion‐weighted EPI; 3D magnetization prepared rapid acquisition gradient echo (MPRAGE).
Statistical Tests
Repeated measures analysis of variance and Tukey post hoc tests were performed to compare fractional anisotropy (FA) values obtained by different methods.
Assessment
FA and corresponding absolute error maps were obtained using TOPUP, DICOT, INVERSION (Inverse contrast Normalization for VERy Simple registratION) and NO CORR (no correction). Each method was assessed by comparing to TOPUP. The pipeline in the ALL patients was evaluated based on the failure rate of the distortion correction using the global correlation values.
Results
Using DICOT reduced the mean absolute errors by an average of 32% in FA in simulation datasets. In 84 patients, the error reductions were approximately 15% in FA with DICOT, while it was 5% with INVERSION. No significant differences between the TOPUP and DICOT were observed in FA with P = 0.090/0.894(AP/PA). Only 15 of 516 examinations requiring any additional manual intervention.
Conclusion
This modified pipeline produced better results than the INVERSION. Furthermore, robust performance was demonstrated in archived patient scans acquired without an inverse PE necessary for TOPUP correction.
Evidence Level
3
Technical Efficacy
Stage 2
The 2-point DIXON method is widely used to assess fat fractions (FFs) in magnetic resonance images (MRIs) of the tongue, pharyngeal wall, and surrounding tissues in patients with obstructive sleep ...apnea (OSA). However, the method is semiquantitative and is susceptible to B0 field inhomogeneities and R2* confounding factors. Using the method, although several studies have shown that patients with OSA have increased fat deposition around the pharyngeal cavity, conflicting findings was also reported in 1 study. This discrepancy necessitates that we examine the FF estimation method used in the earlier studies and seek a more accurate method to measure FFs.
We examined the advantages of using the GOOSE (globally optimal surface estimation) method to replace the 2-point DIXON method for quantifying fat in the tongue and surrounding tissues on MRIs. We first used phantoms with known FFs (true FFs) to validate the GOOSE method and examine the errors in the DIXON method. Then, we compared the 2 methods in the tongue, soft palate, pharyngeal wall, and parapharyngeal fat pad of 63 healthy participants to further assess the errors caused by the DIXON method. Six participants were excluded from the comparison of the tongue FFs because of technical failures. Paired Student t tests were performed on FFs to detect significant differences between the 2 methods. All measures were obtained using 3 T Siemens MRI scanners.
In the phantoms, the FFs measured by GOOSE agreed with the true FF, with only a 1.2% mean absolute error. However, the same measure by DIXON had a 10.5% mean absolute error. The FFs obtained by DIXON were significantly lower than those obtained by GOOSE (P < 0.0001) in the human participants. We found strong correlations between GOOSE and DIXON in the tongue (R2 = 0.90), soft palate (R2 = 0.66), and parapharyngeal fat pad (R2 = 0.88), but the correlation was weaker in the posterior pharyngeal walls (R2 = 0.32) in participants.
The widely used 2-point DIXON underestimated FFs, relative to GOOSE, in phantom measurements and tissues studied in vivo. Thus, an advanced method, such as GOOSE, that uses multiecho complex data is preferred for estimating FF.
Survivors of childhood acute lymphoblastic leukemia (ALL) are at increased risk for neurocognitive problems, with significant interindividual variability in outcome. This study examined genetic ...polymorphisms associated with variability in neurocognitive outcome.
Neurocognitive outcomes were evaluated at the end of therapy in 243 survivors treated on an institutional protocol featuring risk-adapted chemotherapy without prophylactic cranial irradiation. Polymorphisms in genes related to pharmacokinetics or pharmacodynamics of antileukemic agents, drug metabolism, oxidative stress, and attention problems in noncancer populations were examined as predictors of outcome, using multiple general linear models and controlling for age at diagnosis, sex, race, and treatment intensity.
Compared with national norms, the cohort demonstrated significantly higher rates of problems on direct assessment of sustained attention (P = .01) and on parent ratings of attention problems (P = .02). Children with the A2756G polymorphism in methionine synthase (MS) were more likely to demonstrate deficits in attentiveness (P = .03) and response speed (P = .02), whereas those with various polymorphisms in glutathione S-transferase demonstrated increased performance variability (P = .01) and reduced attentiveness (P = .003). Polymorphisms in monoamine oxidase (T1460CA) were associated with increased attention variability (P = .03). Parent-reported attention problems were more common in children with the Cys112Arg polymorphism in apoliopoprotein E4 (P = .01).
These results are consistent with our previous report of association between attention problems and MS in an independent cohort of long-term survivors of childhood ALL treated with chemotherapy only. The results also raise the possibility of an impact from genetic predispositions related to oxidative stress and CNS integrity.
Findings from St Jude Total Therapy Study 16 (Total 16) showed early intensification of triple intrathecal therapy (ITT) improved CNS disease control for children with newly diagnosed acute ...lymphoblastic leukemia (ALL) at the greatest risk of CNS relapse. We examined the impact of this treatment on end-of-therapy neurocognitive outcomes.
Between 2007 and 2017, 400 (83.5%) of 479 eligible patients treated with Total 16 risk-directed chemotherapy completed protocol-directed neurocognitive testing at the end of therapy. Intensified ITT was defined as ≥ 21 cumulative doses for patients with low-risk ALL (n = 70/194) and ≥ 27 doses for those with standard-to-high risk ALL (n = 81/206).
Compared with age-normative expectations, the overall group had significantly lower estimated intelligence quotient (
< .0001), attention (
= .0051), working memory (
= .0001), processing speed (
= .0002), fine motor speed (
= .0001), and math (
= .0087). Caregiver ratings of patient functioning showed elevated risk for problems in attention (
= .0173), executive function (
= .0001), and adaptive skills (
= .0001). Among the low-risk treatment group, there were no significant differences between patients treated with or without intensified ITT (all
.10). Among patients with standard-to-high risk ALL, those treated with intensified ITT had poorer working memory (
= .0328) and fine motor speed (
= .0403), and elevated ratings of inattention (
= .0189) and executive dysfunction (
= .0245). In the standard-to-high risk group, females treated with intensified ITT had lower working memory scores. Public insurance status was associated with worse neurocognitive outcomes in both treatment groups.
Standard-to-high risk patients treated with intensified ITT are at moderately increased risk for neurocognitive problems. The findings suggest a threshold effect for ITT exposure, which can inform the design of future clinical trials and approaches to neurocognitive monitoring and intervention.
Long-term survivors of childhood Hodgkin lymphoma (HL) are at risk for cardiopulmonary complications and CNS stroke, although neurocognitive function has not been previously examined. The aim of this ...study was to examine neurocognitive and brain imaging outcomes in adult survivors of childhood HL.
In all, 62 adult survivors (mean age, 42.2 years; standard deviation SD, 4.77; mean age at diagnosis, 15.1 years; SD, 3.30) were identified by stratified random selection from a large cohort treated with either high-dose (≥ 30 Gy) thoracic radiation (n = 38) or lower-dose (< 30 Gy) thoracic radiation combined with anthracycline (n = 24). Patients underwent neurocognitive evaluations, brain magnetic resonance imaging (MRI), echocardiograms, pulmonary function tests, and physical examinations.
Compared with national age-adjusted norms, HL survivors demonstrated lower performance on sustained attention (P = .004), short-term memory (P = .001), long-term memory (P = .006), working memory (P < .001), naming speed (P < .001), and cognitive fluency (P = .007). MRI revealed leukoencephalopathy in 53% of survivors, and 37% had evidence of cerebrovascular injury. Higher thoracic radiation dose was associated with impaired cardiac diastolic function (E/E'; ratio of peak mitral flow velocity of early rapid filling E to early diastolic velocity of the mitral annulus E'; P = .003), impaired pulmonary function (diffusing capacity of lungs for carbon monoxide DL(co)(corr); P = .04), and leukoencephalopathy (P = .02). Survivors with leukoencephalopathy demonstrated reduced cognitive fluency (P = .001). Working memory impairment was associated with E/E', although impaired sustained attention and naming speed were associated with DL(co)(corr). Neurocognitive performance was associated with academic and vocational functioning.
These results suggest that adult long-term survivors of childhood HL are at risk for neurocognitive impairment, which is associated with radiologic indices suggestive of reduced brain integrity and which occurs in the presence of symptoms of cardiopulmonary dysfunction.
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