Now you see it, now you don’t: statistical and methodological considerations in fMRI

Loring, David W.; Meador, Kimford J.; Allison, J. B.; Pillai, Jay J.; Lavin, T.; Lee, G.P; Balan, Aparna; Dave, Vachik S.

doi:10.1016/s1525-5050(02)00558-9

Cited by 65 publications

(38 citation statements)

References 24 publications

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“…fMRI results may depend on, for example, scanner strength, analysis methods, type of task contrast used, patient compliance and cooperation with the tasks, or medications administered at the time of the procedure; neither selection of fMRI tasks nor data processing methods have been universally standardized. [1][2][3][4] Nonetheless, standard practices are beginning to emerge. 5 The IAP language or memory testing is also not standardized; the reviewed studies vary with regard to the procedure used for comparison.…”

Section: Results and Recommendationsmentioning

confidence: 99%

Practice guideline summary: Use of fMRI in the presurgical evaluation of patients with epilepsy

et al. 2017

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Objective: To assess the diagnostic accuracy and prognostic value of functional MRI (fMRI) in determining lateralization and predicting postsurgical language and memory outcomes.Methods: An 11-member panel evaluated and rated available evidence according to the 2004 American Academy of Neurology process. At least 2 panelists reviewed the full text of 172 articles and selected 37 for data extraction. Case reports, reports with ,15 cases, metaanalyses, and editorials were excluded. Results and recommendations:The use of fMRI may be considered an option for lateralizing language functions in place of intracarotid amobarbital procedure (IAP) in patients with medial temporal lobe epilepsy (MTLE; Level C), temporal epilepsy in general (Level C), or extratemporal epilepsy (Level C). For patients with temporal neocortical epilepsy or temporal tumors, the evidence is insufficient (Level U). fMRI may be considered to predict postsurgical language deficits after anterior temporal lobe resection (Level C). The use of fMRI may be considered for lateralizing memory functions in place of IAP in patients with MTLE (Level C) but is of unclear utility in other epilepsy types (Level U). fMRI of verbal memory or language encoding should be considered for predicting verbal memory outcome (Level B). fMRI using nonverbal memory encoding may be considered for predicting visuospatial memory outcomes (Level C). Presurgical fMRI could be an adequate alternative to IAP memory testing for predicting verbal memory outcome (Level C). Clinicians should carefully advise patients of the risks and benefits of fMRI vs IAP during discussions concerning choice of specific modality in each case. Neurology ® 2017;88:395-402 GLOSSARY AAN 5 American Academy of Neurology; ATL 5 anterior temporal lobe; fMRI 5 functional MRI; IAP 5 intracarotid amobarbital procedure; LI 5 laterality index; MTL 5 medial temporal lobe; MTLE 5 medial temporal lobe epilepsy; ROI 5 region of interest; TLE 5 temporal lobe epilepsy.This article summarizes an American Academy of Neurology (AAN) guideline on use of functional MRI (fMRI) for presurgical mapping in epilepsy. Additional information is provided in the complete guideline, available as a data supplement at Neurology.org. Appendices e-1 through e-5, available in the complete guideline, tables e-1 and e-2, and references e1-e16, cited here, are available at Neurology.org.The choice of performing intracarotid amobarbital procedure (IAP) or fMRI for presurgical language and memory assessment depends on multiple factors that need to be taken into account when selecting the study. fMRI is properly described as an image acquisition technique that has come to mean imaging brain activity. fMRI results may depend on, for example, scanner strength, analysis methods, type of task contrast used, patient compliance and cooperation with the tasks, or medications administered at the time of the procedure; neither selection of fMRI tasks nor data processing methods have been universally standardized.1-4 Nonetheless, standard prac...

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Section: Results and Recommendationsmentioning

confidence: 99%

Practice guideline summary: Use of fMRI in the presurgical evaluation of patients with epilepsy

et al. 2017

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“…With the GLM method, approaches have been used to limit type I error associated with multiple comparisons, e.g., Bonferroni correction (Maxwell and Delaney, 1990), random field theory (RFT, Worsley et al, 1996), and false discovery rate (FDR, Benjamini and Hochberg, 1995). However adjustments to control type I error are at the expense of type II error, which is failing to obtain statistical significance when the effects are genuinely present (Loring et al, 2002). For pre-surgical language mapping, type II error is more relevant since it may result in falsely underestimating the extent of critical language cortex and thus resulting in an underestimate of potential surgical risk to language function.…”

Section: Comparison Of Ica and Glm Resultsmentioning

confidence: 99%

“…The null hypothesis is "no activation", and type I error of finding activations by chance is controlled by criteria of statistical significance selected by the investigator. However in pre-surgical mapping applications, an excessively conservative criterion used to identify activations in the functional areas has the potential of falsely indicating absence of surgical risk by removing the activated voxels genuinely associated with the task (Loring et al, 2002). This kind of type II error of failing to obtain statistical significance when the effects are genuinely present is particularly relevant to pre-surgical functional mapping, in order to avoid harming critical cortical areas during surgery.…”

Section: Introductionmentioning

confidence: 99%

Group independent component analysis of language fMRI from word generation tasks

et al. 2008

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Language fMRI has been used to study brain regions involved in language processing and has been applied to pre-surgical language mapping. However, in order to provide clinicians with optimal information, the sensitivity and specificity of language fMRI needs to be improved. Type II error of failing to reach statistical significance when the language activations are genuinely present may be particularly relevant to pre-surgical planning, by falsely indicating low surgical risk in areas where no activations are shown. Furthermore, since the execution of language paradigms involves cognitive processes other than language function per se, the conventional general linear model (GLM) method may identify non-language-specific activations. In this study, we assessed an exploratory approach, independent component analysis (ICA), as a potential complementary method to the inferential GLM method in language mapping applications. We specifically investigated whether this approach might reduce type II error as well as generate more language-specific maps. Fourteen right-handed healthy subjects were studied with fMRI during two word generation tasks. A similarity analysis across tasks was proposed to select components of interest. Union analysis was performed on the languagespecific components to increase sensitivity, and conjunction analysis was performed to identify language areas more likely to be essential. Compared with GLM, ICA identified more activated voxels in the putative language areas, and signals from other sources were isolated into different components. Encouraging results from one brain tumor patient are also presented. ICA may be used as a complementary tool to GLM in improving pre-surgical language mapping.

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“…Only results that were significant at the Family Wise Error (FWE) (Loring et al, 2002) corrected level at P < 0.01 are reported. The localization of brain activation was aided by the Anatomical Automatic Labelling toolbox (Tzourio-Mazoyer et al, 2002).…”

Section: Discussionmentioning

confidence: 99%

Extended cortical activations during evaluating successive pain stimuli

Lötsch

Walter

Felden

et al. 2011

Social Cognitive and Affective Neuroscience

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Comparing pain is done in daily life and involves short-term memorizing and attention focusing. This event-related functional magnetic resonance imaging study investigated the short-term brain activations associated with the comparison of pain stimuli using a delayed discrimination paradigm. Fourteen healthy young volunteers compared two successive pain stimuli administered at a 10 s interval to the same location at the nasal mucosa. Fourteen age-and sex-matched subjects received similar pain stimuli without performing the comparison task. With the comparison task, the activations associated with the second pain stimulus were significantly greater than with the first stimulus in the anterior insular cortex and the primary somatosensory area. This was observed on the background of a generally increased stimulus-associated brain activation in the presence of the comparison task that included regions of the pain matrix (insular cortex, primary and secondary somatosensory area, midcingulate cortex, supplemental motor area) and regions associated with attention, decision making, working memory and body recognition (frontal and temporal gyri, inferior parietal lobule, precuneus, lingual cortices). This data provides a cerebral correlate for the role of pain as a biological alerting system that gains the subject's attention and then dominates most other perceptions and activities involving pain-specific and non-pain-specific brain regions.

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Now you see it, now you don’t: statistical and methodological considerations in fMRI

Cited by 65 publications

References 24 publications

Practice guideline summary: Use of fMRI in the presurgical evaluation of patients with epilepsy

Practice guideline summary: Use of fMRI in the presurgical evaluation of patients with epilepsy

Group independent component analysis of language fMRI from word generation tasks

Extended cortical activations during evaluating successive pain stimuli

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