***Methodological Checklist for fMRI Drug Cue Reactivity Studies: Development and Consensus*** **2.1. Scope of the Checklist** The items included in the checklist are going to be those assumed to be important to be reported specifically in fMRI drug cue-reactivity (FDCR) studies. This checklist will be developed to act as a standalone tool for all methodological details that are considered having a significant effect on the final results of FDCR studies. The authors will make additional recommendations for each item to increase the quality of reporting. The checklist will be used to facilitate future data sharing between labs and to make increasingly sophisticated meta-analyses possible. **2.2. Contributors** The contributions to this project are organized on two levels, that of a steering committee and a larger expert panel. This methodology is developed as it enables a small and tightly connected group of experts to flexibly and rapidly make important decisions and resolve complex conflicts and lead the project to fruition while ensuring that the voices of a much wider and more diverse group of international experts meaningfully impact the consensus process. *2.2.1. Steering Committee (SC)* The SC consists of Hugh Garavan, Anna Zilverstand, Amy Janes, Rita Goldstein, Andreas Heinz, Lara Ray, Elliot Stein, Rajita Sinha, Reagan Wetherill, Jane E. Joseph, Joseph McClernon, Anna Rose Childress, Hedy Kober, Martin Paulus, and Hamed Ekhtiari. This group grew out of the ENIGMA addiction working group after a series of meetings in which substantial heterogeneities in FDCR studies, poor reporting of methods, and confusion over the importance of various methodological parameters were discussed along with strategies to amend the situation. Additionally, the initial members of the SC will be asked to co-opt additional members chosen on the basis of their specific scientific competence. The SC members will outline the scope of the Delphi project and its important questions, approve the initial checklist of important methodological parameters, process the comments and ratings, and lead the authorship of this manuscript, all according to consensus. *2.2.2. Expert Panel (EP)* The panel of experts for this Delphi study will be chosen based primarily on a systematic review of 317 addiction-related FDCR [paper not published]. The main inclusion criteria are that a) appearing among the authors of at least 4 papers in the systematic review database and b) holding first, last or corresponding authorship position in at least one of the 317 papers. In addition, the members of the SC will be asked to nominate candidates in the field of FDCR for inclusion within the EP. All SC members should agree on the list of experts before the invitation process. All the chosen experts will be sent an email briefly outlining the importance, structure, and goals of this Delphi study. The experts will be asked to state if they would wish to participate, those who decide to enroll will receive a further email with more details about how their feedback would be collected and used in the Delphi study and then they formally will enter the Delphi process. **2.3. Procedure** *2.3.1. Panel management* Providing experts with information is not necessary for Delphi studies which do not rely on explicit information and published data (Jorm, 2015) and many examples of such studies exist (e.g.,(Forsman et al., 2015). The experts will be asked to primarily rely on their prior knowledge of FDCR task design and methodology during the Delphi process, and they will be provided with the list of the 317 studies included in the aforementioned systematic review so they can view the articles if they wish so. *2.3.2 Checklist development* To simplify consensus development and to facilitate the process of finalizing a comprehensive but concise list of the various important methodological aspects of FDCR studies, we decide to begin the feedback rounds after developing a basic set of items and categories we assume would cover the most essential aspects of methodological parameter space of FDCR. This basic structure will evolve slowly based on the initial feedback of the SC, and a consideration of the methodological parameters commonly observed to be important to the studies included in the aforementioned systematic review. The use of focus groups and systematic searches to develop initial questionnaires in Delphi studies has been noted in mental health Delphi studies (Jorm, 2015). Upon completion, the questionnaire will be pilot tested by five expert panel members. Using data from the pilot testing analysis, the steering committee will reword and/or combine items that are deemed unclear for inclusion in round one. *2.3.3. Process* *2.3.3.1. First Round* In the first round, N experts who accept the invitation, along with SC members, will be sent the checklist and will be asked to add comments and suggest revisions to existing items. They will also be asked to suggest new items that they feel are overlooked, along with an explanation of why they think the item should be included. They also will be told that there are no limits to the number of new items they could suggest for addition. If they wish so, they will also be given the option to provide general comments about the structure of the checklist and the consensus process. This will not be repeated in the two subsequent rounds. In the first round, members of the SC and EP will also be asked to answer a short questionnaire comprised of a few questions from the responders (Chipchase et al., 2012) assessing their demographic information (age, sex, highest academic degree, country of residence, primary affiliation), primary field of research (psychiatry, psychology, pharmacology, neuroscience, cognitive science, etc.), primary place of work (university, hospital, business, independent research institute, etc.), length of time spent in addiction medicine, and length of time spent specifically researching FDCR. These questions are not going to be included in the subsequent rounds, and they will be asked to ensure we have succeeded in including a diverse field of experts. We have measures in place to attempt to achieve a response rate of >80%. For this and other rounds, participants will be told that they have two weeks to return the questionnaire. At ten days, they will again be reminded of the deadline. Those who fail to meet the two-week deadline will be asked to return the questionnaire within a single week, and this will be repeated after one more week or until the non-responders replied. Comments for each item are going to be thematically analyzed and processed by members of the SC. During processing, repetitive comments will be removed and items with unclear meaning will be reworded and those outside the scope of the study will be removed (Hasson, Keeney, & McKenna, 2000). So a list of clear and unique single-point notes extracted from the comments will be obtained. The notes obtained after the processing of comments will be of three kinds: First, proposed changes to an existing item or its associated recommendations; second, adding or removing items; and third, general changes or critiques regarding the checklist. The decision of applying or rejecting each note will be made by consensus among the SC (Jorm, 2015). *2.3.3.2. Second Round* In the second round, participants from the SC and EP will be sent the edited checklist along with the approved new items. The experts will be asked to rate each item in terms of importance in the methodology of FDCR studies, from 1 to 5 (T% of them completed the entire survey). The exact question is going to be: “To facilitate visibility, replication and data sharing, how important is it to report this item?“. In order to avoid a non-neutral center rating and encourage deliberation, ratings are termed “not important”, “slightly important”, “moderately important”, “highly important” and “extremely important”. The authors will be allowed not to rate an item if they do not wish to do so. The items which are rated 4 or 5 (highly or extremely important) from more than 80% of the participants in the second round will be approved for inclusion in the final checklist. On the other hand, the items gaining a score of 3 or less from more than 80% of the participants will be rejected promptly (Berk, Jorm, Kelly, Dodd, & Berk, 2011; Yucel et al., 2019). The status of items not reaching 80% consensus to be included or excluded will be determined by the third round. *2.3.3.3. Third Round* Participants from EP and SC will be provided with the items that have not reached the 80% consensus to be included or excluded. Participants will provide a vote with Yes or No to include the item. The majority vote will decide the items that remain in the checklist. **2.4. Data Analysis** All quantitative analyses will be conducted using Excel (Microsoft Office 2016). To designate an item as finalized, the average rating and the number of responses will be calculated. Also, for items that are passed to the subsequent round, to evaluate the stability of each item, the percentage of change will be calculated through the rounds (Scheibe, Skutsch, & Schofer, 1975). References: Berk, L., Jorm, A. F., Kelly, C. M., Dodd, S., & Berk, M. (2011). Development of guidelines for caregivers of people with bipolar disorder: a Delphi expert consensus study. Bipolar Disord, 13(5-6), 556-570. doi:10.1111/j.1399-5618.2011.00942.x Chipchase, L., Schabrun, S., Cohen, L., Hodges, P., Ridding, M., Rothwell, J., . . . Ziemann, U. (2012). A checklist for assessing the methodological quality of studies using transcranial magnetic stimulation to study the motor system: an international consensus study. Clin Neurophysiol, 123(9), 1698-1704. doi:10.1016/j.clinph.2012.05.003 Forsman, A. K., Wahlbeck, K., Aaro, L. E., Alonso, J., Barry, M. M., Brunn, M., . . . Consortium, R. 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