Back to Authors

Wu, Teddy Y

0000-0003-1845-1769

Mayo Clinic

Christchurch Hospital

Citations 5

Diagnostic Yield of Cardiac CT to Detect Cardiac Thrombi in Patients With Acute Ischemic Stroke (AIS of HEARTS)
Nio, Shan Sui , Green, Daniel S. , Berry-Noronha, Alexander , Rinkel, Leon A. , Beemsterboer, Chiel F.P. , Hasnain, Md Golam , Planken, R. Nils , Randen, Adriënne van , Al-Hadethi, Sinan , Hilt, Mirre G.M. , Ruhe, Deborah S.A., Boekholdt, S Matthijs, Chew, Beng Lim Alvin , Fridgant, Joshua, Mena-Romo, Luis , Kim, Dong Hyun, Guo, Shuyu, Winders, Joel, Senadeera, Sajith C. , Lim, Anthony , Fink, John, Leung, Melissa , Cordato, Dennis, Spratt, N., Collaborators, on behalf of the AIS of HEARTS, Green, Daniel S , van Randen, Adrienne , Bouma, Berto J , Boekholdt, S Matthijs , Fridgant, Joshua , Mena-Romo, Luis , Alamri, Yassar , Lim, Anthony T , Leung, Melissa , Cordato, Dennis , Parsons, Mark W , Spratt, Neil J , Garcia-Esperon, Carlos , Wu, Teddy Y , Coutinho, Jonathan M , Beemsterboer, Chiel F P , Planken, R Nils , Berry‐Noronha, Alexander , Hasnain, Md Golam , Hilt, Mirre , Ruhe, Deborah, Bouma, Berto J. , Boekholdt, S. Matthijs , Kim, Dong Hyun, Fink, John

Stroke | June 2, 2026 | Volume: 57 | Issue: 8 | Pages: 2408-2416

10.1161/strokeaha.126.055575 Get It

BACKGROUND: Cardiac computed tomography (CT) acquired during the acute stroke imaging protocol is an emerging modality to detect cardiac thrombi. We determined its yield in patients with acute ischemic stroke. METHODS: We performed a 1-stage individual patient data meta-analysis of 4 prospective observational cohorts (AIS of HEARTS [Acute Ischemic Stroke of Heart-Related Embolic Sources Detected on Acute Cardiac CT Scans]), including patients with acute ischemic stroke who underwent ECG-gated or non–ECG-gated cardiac CT between May 2018 and June 2024. We excluded patients with transient ischemic attack or stroke mimics. The primary outcome was the proportion of patients with a thrombus on cardiac CT. Secondary outcomes were additional scan time, radiation dose, comparison with echocardiography, and 90-day outcomes. We performed logistic regression analyses to compare 90-day outcomes between patients with and without thrombus, adjusting for age, sex, history of atrial fibrillation, ischemic heart disease, chronic heart failure, stroke or transient ischemic attack, anticoagulant use, prestroke modified Rankin Scale score, National Institutes of Health Stroke Scale score, large vessel occlusions, and intravenous thrombolysis, as appropriate for each outcome. RESULTS: We included 3919 patients (median age, 74 [interquartile range (IQR), 63–82], 58% male, median National Institutes of Health Stroke Scale score 6 [IQR, 3–12]). Cardiac CT detected a thrombus in 243 (6.2%) patients. Among 1323 patients that underwent both cardiac CT and transthoracic echocardiography, cardiac CT had a higher yield than transthoracic echocardiography (odds ratio, 7.4 [95% CI, 4.0–15.1]; P <0.001). Median additional scan time was 6 minutes (IQR, 5–7) for ECG-gated and 13 seconds (IQR, 12–61) for non–ECG-gated cardiac CT. Median additional radiation dose was 2.9 mSv (IQR, 1.6–4.1). Patients with thrombi had higher 90-day mortality (33% versus 15%, adjusted odds ratio, 1.6 [95% CI, 1.1–2.3]) and worse modified Rankin Scale scores (median modified Rankin Scale score 3 versus 2, adjusted odds ratio, 1.6 [95% CI, 1.2–2.0]), but similar recurrent stroke rates (5% versus 4%, adjusted odds ratio, 1.4 [95% CI, 0.7–2.5]). CONCLUSIONS: Implementing cardiac CT into the acute stroke imaging protocol is feasible, detects thrombi in ≈6% of patients, and has a higher yield than transthoracic echocardiography. Cardiac thrombi were associated with higher mortality, but not higher stroke recurrence. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT07165093.
Abstract A029: Diagnostic Yield of Cardiac CT to Detect Cardiac Thrombi in Acute Ischemic Stroke: an Individual Patient Data Meta-Analysis.
Nio, Shan Sui , Green, Daniel B. , Berry, Alexander , Rinkel, Leon A, Planken, R. Nils, Randen, Adriënne van , Hilt, Mirre , Ruhe, Deborah, Bouma, B., Boekholdt, S, Chew, Beng Lim Alvin , Fridgant, Joshua, ROMO, LUIS MENA, Guo, Shuyu, Winders, Joel, Senadeera, Sajith C. , Lim, Anthony , Fink, John , Leung, Melissa , Parsons, Mark, Spratt, N., Garcia-Esperon, Carlos, Wu, Teddy, Coutinho, Jonathan M. , Green, Daniel, Rinkel, Leon A. , Beemsterboer, Chiel F.P. , Hasnain, Md Golam , Planken, R. Nils , Boekholdt, S. Matthijs , Romo, Luis Mena, Kim, Dong Hyun , Alamri, Yassar , Lim, Anthony T , Leung, Melissa , Cordato, Dennis , Spratt, Neil J , Garcia-Esperon, Carlos , Wu, Teddy Y

Stroke | January 29, 2026 | Volume: 57 | Issue: Suppl_1 | Pages: No page available

10.1161/str.57.suppl_1.a029 Get It

Background: Cardiac CT acquired during the acute stroke imaging protocol is an emerging diagnostic modality to detect cardiac thrombi. We aimed to determine its diagnostic yield in a large, international, multicenter study. Methods: We performed an individual patient data meta-analysis by pooling prospective and retrospective observational data of patients with acute ischemic stroke (AIS) who underwent cardiac CT (ECG-gated or non-ECG-gated) as part of the acute imaging protocol between May 2018 and June 2024. We excluded patients with a TIA or stroke mimic. The primary outcome was the proportion of patients with a cardiac thrombus detected on cardiac CT. Secondary outcomes were additional scan time and radiation dose, comparison of yield with echocardiography, and 90-day mortality and recurrent ischemic stroke rates. Results: We included 3940 patients from 4 hospitals (median age 74 [IQR 63-82], 58.0% male, median NIHSS 6 [IQR 3-12], median time onset to hospital arrival 100 minutes [IQR 62-185]). Atrial fibrillation at baseline was present in 23.1% patients, and 29.6% had a large vessel occlusion. Cardiac CT was non-diagnostic in 17 (0.4%) patients. In total, cardiac CT detected 254 cardiac thrombi in 243/3923 (6.2%) patients. Thrombi were located in the left atrial appendage (n=193), left atrium (n=19), and left ventricle (n=42). Of 95/243 (39.1%) patients with a cardiac thrombus that underwent echocardiography (median interval cardiac CT-echocardiography: 2 days), transthoracic echocardiography detected a thrombus in 18/92 (19.6%) patients and transesophageal echocardiography in 2/5 (40.0%) patients. The diagnostic yield in patients that underwent both modalities was higher for cardiac CT (OR 7.5 [CI 4.0-15.3], p<0.001). Median additional scan time was 6 minutes (IQR 5-7) for ECG-gated and 17 seconds (IQR 15-63) for non-ECG-gated cardiac CT. Median additional radiation dose was 5.4mSv (IQR 3.0-7.6). Patients with a cardiac thrombus on cardiac CT had higher 90-day mortality than those without a thrombus (33.3% vs 14.6%, p<0.001). We found no difference in 90-day recurrent stroke rate (5.4% vs 4.4%, p=0.50). Conclusion: Routine cardiac CT performed during the acute stroke imaging protocol detects a cardiac thrombus in 1 out of 16 patients with AIS, with a 7-times higher yield than routine echocardiography. Mortality rate was doubled in patients with a cardiac thrombus, but 90-day stroke recurrence risk did not differ.
Abstract DP126: ECG-gated versus non-ECG-gated cardiac CT protocols for cardiac thrombus detection in acute ischemic stroke.
ROMO, LUIS MENA, Nio, Shan Sui , Berry, Alexander , Spratt, N., Green, Daniel, Hasnain, Md, Chew, Beng Lim Alvin , Fridgant, Joshua, Rinkel, Leon A, Beemsterboer, Chiel, Planken, R. Nils, Randen, Adriënne van , Hilt, Mirre, Ruhe, Deborah, Bouma, B., Boekholdt, S, Kim, Dong Hyun, Guo, Shuyu, Winders, Joel, Senadeera, Sajith C. , Lim, Anthony , Fink, John , Leung, Melissa, Parsons, Mark, Wu, Teddy, Coutinho, Jonathan, Garcia-Esperon, Carlos, Romo, Luis Mena, Spratt, Neil J , Hasnain, Md Golam , Rinkel, Leon A. , Beemsterboer, Chiel F.P. , Planken, R. Nils , Hilt, Mirre , Boekholdt, S. Matthijs , Alamri, Yassar , Lim, Anthony T , Cordato, Dennis , Parsons, Mark W , Wu, Teddy Y , Garcia-Esperon, Carlos

Stroke | January 29, 2026 | Volume: 57 | Issue: Suppl_1 | Pages: No page available

10.1161/str.57.suppl_1.dp126 Get It

Background: The rate of intracardiac thrombus detection in the hyperacute phase of stroke varies from 5% to 12% between studies. Our aim was to compare the thrombus detection rate between ECG-gated and non-ECG-gated cardiac CT protocols in acute stroke patients, using data from a large, international, multicentre registry. Methods: We conducted an individual patient data meta-analysis by pooling prospective and retrospective observational data from stroke patients assessed at four comprehensive stroke centres who underwent either ECG-gated or non-ECG-gated cardiac CT (extended CT angiography or two-phase non-ECG-gated cardiac CT) as part of the acute stroke imaging protocol between May 2018 and June 2024. The primary outcome was the proportion of patients with a cardiac thrombus in gated vs non gated techniques. Results: Of 3,940 patients, 1,474 (37.4%) underwent ECG-gated and 2,466 (62.6%) non-ECG-gated cardiac CT. Patients in the ECG-gated group were younger (median age 72 [IQR 62–81] vs. 74 [IQR 64–82] years, p = 0.000) and had a lower NIHSS at baseline (median 5 [IQR 2–12] vs. 6 [IQR 3–13], p < 0.00). There was a higher rate of thrombus detection with ECG-gated CT compared to non-gated CT (7.5% vs. 5.5%, p = 0.011. The association remained significant after adjusting for age, sex, baseline NIHSS score, and baseline atrial fibrillation (adjusted OR 1.87, 95% CI 1.42–2.47, p = 0.000). ECG-gated CT was associated with lower radiation dose (3.6 vs. 6.3 mSv, p = 0.000) but longer acquisition time (5.8 vs. 0.28 min, p = 0.000). Conclusion: ECG-gated cardiac CT has a higher detection rate for intracardiac thrombus detection compared to non-ECG-gated CT in patients with acute ischemic stroke.
Usability and feasibility of PreventS-MD web app for stroke prevention
Feigin, Valery L. , Krishnamurthi, Rita , Medvedev, Oleg N. , Merkin, Alexander, Nair, Balakrishnan, Jalili-Moghaddam, Shabnam, Barker‐Collo, Suzanne , Ratnasabapathy, Yogini , Skinner, Luke C , Sachdev, Perminder S. , Brainin, Michael , Hankey, Graeme J. , Azarpazhooh, Reza, Bhatia, Anjali , Budinčević, Hrvoje , Child, Nicholas, Chwojnicki, Kamil , Correia, Manuel, Davis, Alan , Devlin, Gerry , Demarin, Vida , Dhamija, Rajinder K. , Ding, Ding , Докова, Клара , Dudley, Makarena , Dyer, Jesse, Edmonds, Misty , Ely, Marcela , Feigin, Svetlana , Fornolles, C, Gall, Seana , Gil, Artyom , George, Ann, Haršány, Michal , Harwood, Matire, Hou, Zeng‐Guang , Ibrahim, Norlinah Mohamed, Ka‘ai, Tania , Kalra, Nidhi , Katzenellenbogen, Judith , Kang, Law Zhe, Kar, Arindam , Kazin, Vitalij, Kamenova, Saltanat , Kondybaeva, A., Lavados, Pablo M, Lee, Tsong‐Hai , Liu, Liping , Mahawish, Karim , Maluchnik, Michał , Martins, Sheila , Mavaddat, Nahal , Mehndiratta, Man Mohan, Oliver, Angela , Öztürk, Şerefnur , Patel, Nikhil, Prakash, B, Roos, Kev, Sekaran, Lakshmanan , Shamalov, N. А. , Solomon, Alina, Suwanwela, Nijasri C., Volevach, Ekaterina , Volný, Ondřej , Wan, Joyce, Withanapathirana, Katila, Welte, Tamara, Wiebers, David O. , Zaidi, Wan Asyraf Wan , Kravchenko, Michael , Barker-Collo, Suzanne , Owolabi, Mayowa , Sachdev, Perminder S , Brainin, Michael , Thrift, Amanda , Hankey, Graeme J , Katzenellenbogen, Judith M , Nair, Balakrishnan, Kravchenko, Michael , Jalili‐Moghaddam, Shabnam , Norrving, Bo , Arroll, Bruce , Thrift, Amanda G. , Abd-Allah, Foad , Akinyemi, Rufus , Bath, Philip M. , Brayne, Carol , Child, Nicholas, Farhoudi, Mehdi , Aziz, Aznida Firzah Abdul , Gabriel, Denis , Gnedovskaya, Elena V. , Harwood, Matire L. N. , Hillis, Argye Elizabeth , Hwang, Kevin O. , Ibrahim, Norlinah Mohamed , Kalra, Nidhi, Karaszewski, Bartosz , Kivipelto, Miia , Lavados, Pablo M. , Mateen, Farrah J. , Mikulík, Robert , Oliver, Angela, Patel, Nikhil, Пирадов, М. А. , Purvis, Tara L. , Reips, Ulf‐Dietrich , Rosand, Jonathan M. , Sahathevan, Ramesh , Silva, Deidre Anne De , Singh, Vinod, Srivastava, M.V. Padma , Taylor, Denise M. , Truelsen, Thomas Clement , Venketasubramanian, Narayanaswamy , Winkler, Andrea Sylvia , Wijeratne, Tissa , Wu, Teddy Y

International Journal of Stroke | July 24, 2023 | Volume: 19 | Issue: 1 | Pages: 94-104

10.1177/17474930231190745 Get It

Background: Most strokes and cardiovascular diseases (CVDs) are potentially preventable if their risk factors are identified and well controlled. Digital platforms, such as the PreventS-MD web app (PreventS-MD) may aid health care professionals (HCPs) in assessing and managing risk factors and promoting lifestyle changes for their patients. Methods: This is a mixed-methods cross-sectional two-phase survey using a largely positivist (quantitative and qualitative) framework. During Phase 1, a prototype of PreventS-MD was tested internationally by 59 of 69 consenting HCPs of different backgrounds, age, sex, working experience, and specialties using hypothetical data. Collected comments/suggestions from the study HCPs in Phase 1 were reviewed and implemented. In Phase 2, a near-final version of PreventS-MD was developed and tested by 58 of 72 consenting HCPs using both hypothetical and real patient (n = 10) data. Qualitative semi-structured interviews with real patients (n = 10) were conducted, and 1 month adherence to the preventive recommendations was assessed by self-reporting. The four System Usability Scale (SUS) groups of scores (0–50 unacceptable; 51–68 poor; 68–80.3 good; >80.3 excellent) were used to determine usability of PreventS-MD. Findings: Ninety-nine HCPs from 27 countries (45% from low- to middle-income countries) participated in the study, and out of them, 10 HCPs were involved in the development of PreventS before the study, and therefore were not involved in the survey. Of the remaining 89 HCPs, 69 consented to the first phase of the survey, and 59 of them completed the first phase of the survey (response rate 86%), and 58 completed the second phase of the survey (response rate 84%). The SUS scores supported good usability of the prototype (mean score = 80.2; 95% CI [77.0–84.0]) and excellent usability of the final version of PreventS-MD (mean score = 81.7; 95% CI [79.1–84.3]) in the field. Scores were not affected by the age, sex, working experience, or specialty of the HCPs. One-month follow-up of the patients confirmed the high level of satisfaction/acceptability of PreventS-MD and (100%) adherence to the recommendations. Interpretation: The PreventS-MD web app has a high level of usability, feasibility, and satisfaction by HCPs and individuals at risk of stroke/CVD. Individuals at risk of stroke/CVD demonstrated a high level of confidence and motivation in following and adhering to preventive recommendations generated by PreventS-MD.
Mechanical Thrombectomy Global Access For Stroke (MT-GLASS): A Mission Thrombectomy (MT-2020 Plus) Study
Asif, Kaiz , Otite, Fadar Oliver , Desai, Shashvat M. , Herial, Nabeel , Inoa, Violiza , Al‐Mufti, Fawaz , Dmytriw, Adam A. , Castonguay, Alicia C. , Khandelwal, Priyank , Potter‐Vig, Jennifer , Szeder, Viktor , Kulman, Tanzila, Masoud, Hesham , Tóth, Gábor , Limaye, Kaustubh , Aroor, Sushanth , Brinjikji, Waleed , Rai, Ansaar , Gebreyohanns, Mehari , Leung, Thomas , Mansour, Malek , Huded, Vikram , Zaidat, Osama O. , Sylaja, PN , Yavagal, Dileep R. , Cirio, Juan , Lylyk, Pedro , Ferrario, Ángel, Plaghos, Luis Lemme, Ibrahim, Wael Hamed, Alnidawi, Firas , Islam, Sirajee Shafiqul, Shahidullah, Mohammad, Saavedra, Víctor Villarroel, Alverne, Francisco Josà Mont’, Magalhães, Pedro , Sirakov, Stanimir , Kalpachki, Rosen, Alioski, Nurfet, Lamou, Eric Gueumekane Bila , Rowe, Daidre, Gayle, Francene , Souza, Romnesh de, Ramos, Cristina , GarcÃa, Amaury, Ali, Amza , Sandy, Sherry , Guzman, Tony Fabian Alvarez, Villarraga, Alejandro, Estrada, Carolina, Pabón, B , Adebayo, Philip , ABDO, GERMAN, S, Nelson Maldonado, Khinikadze, Mirza, Tsiskaridze, Alexander , Syrmos, Νikolaos , Mitsias, Panayiotis , Das, Biplab , Gupta, Vipul , Karapurkar, Anil, Stivastava, M.V.Padma, Alurkar, Anand, Sharma, Arvind , Lahoti, Satish, Kuruttukulam, Gigy , Sari, Ita Muharram , Khassaf, Mustafa Saleem, Nassir, Temeem Majid, Yamagami, Hiroshi , Dababneh, Haitham, Aladham, Farid A., Berdikhojayev, Mynzhylky , Medukhanova, Sabina , Kikano, Raghid, Alaraj, Ali , Ahdab, Rechdi , Zaidi, Wan Asyraf Wan , Kadir, Khairul Azmi Abd, Gongora, Fernando, Jambaldorj, Ariunaa , XXX, Ganbaatar, Shwe, Zarni Myint, Thit, Win Min , RAYO, ERWIN E., Makanjuola, Akintomiwa , Rashid, Umair, Mernes, Ricardo, Paniagua, Osvaldo, GALLO, MARLA, Moquillaza, Manuel, Collantes, Maria Epifania , Mariano, Manuel, Kobayashi, Adam , Rodríguez‐Mercado, Rafael, Guardia, Rodolfo Alcedo, Imam, Yahia , Ahmed, Ayman Z., Al-Jehani, Hosam , Lee, Wickly, Klepanec, Andrej , Brey, Naeem , Rossouw, Anastasia, Silva, Prasad De, Gunasekera, Harsha, Ranawaka, Udaya K. , Osman, Haytham , El-Sadig, Sarah , Suwanwela, Nijasri C., Akarathanawat, Wasan, Tantivatana, Jarturon , Hammami, Nadia, Giray, Semih , Lebedynets, Dmytro , Konotopchik, Stanislav, John, Seby , Hussain, Syed , Novakovic-White, Robin, Perue, Gillian L Gordon, Then, Ryna , Berrutti, Claudio, Crosa, Roberto , Nguyen, Huy Thang, Le, Huynh Vu, vu, Tran thanh, Asif, Kaiz S , Otite, Fadar O , Jadhav, Ashutosh P , Dmytriw, Adam A , Castonguay, Alicia , Khandelwal, Priyank , Szeder, Viktor , Urrutia, Victor C , Masoud, Hesham , Toth, Gabor , Limaye, Kaustubh , Brinjikji, Waleed , Rai, Ansaar , Pandian, Jeyaraj , Leung, Thomas , Mansour, Ossama , Demchuk, Andrew M , Martins, Sheila , Zaidat, Osama O , Huo, Xiaochuan , Campbell, Bruce , Miao, Zhongrong , Saver, Jeffrey , Ortega-Gutierrez, Santiago , Yavagal, Dileep R , Crosa, Roberto , Alaraj, Ali , Al-Mufti, Fawaz , Jadhav, Ashutosh P. , Urrutia, Victor , Pandian, Jeyaraj , Demchuk, Andrew M. , Saver, Jeffrey L. , Arroyo, José, Yan, Bernard , Chandra, Ronil Vikesh , Shahidullah, Mohammad, Alverne, F Mont, Silva, Gisele Sampaio , Shankar, Jai , Stotts, Grant , Ramos, Cristina, Lavados, Pablo M. , Rivera, Rodrigo , Krajina, Antonı́n , Tomek, Aleš , Hassan, Farouk , Khedr, Eman M. , Nadareishvili, Zurab , Roy, Jayanta , Gupta, Vivek , Khurana, Dheeraj , Kumar, Rahul Kewal , Sani, Achmad Firdaus , Sakai, Nobuyuki , Aladham, Farid, Kikano, Raghid , Araúz, Antonio , Góngora‐Rivera, Fernando , Shwe, Zarni Myint, Ranta, Annemarei , Wu, Teddy Y , Owolabi, Mayowa , Ahmad, Saima , Wasay, Mohammad , Alhazzani, Adel Ali , Zeleňák, Kamil , Krastev, Georgi , Frol, Senta , Hammami, Nadia, Sassi, Samia Ben , Özdemi̇r, Atilla Özcan , Конотопчик, С. В., Perue, Gillian Gordon

Circulation | March 8, 2023 | Volume: 147 | Issue: 16 | Pages: 1208-1220

10.1161/circulationaha.122.063366 Get It

Background: Despite the well-established potent benefit of mechanical thrombectomy (MT) for large vessel occlusion (LVO) stroke, access to MT has not been studied globally. We conducted a worldwide survey of countries on 6 continents to define MT access (MTA), the disparities in MTA, and its determinants on a global scale. Methods: Our survey was conducted in 75 countries through the Mission Thrombectomy 2020+ global network between November 22, 2020, and February 28, 2021. The primary end points were the current annual MTA, MT operator availability, and MT center availability. MTA was defined as the estimated proportion of patients with LVO receiving MT in a given region annually. The availability metrics were defined as ([current MT operators×50/current annual number of estimated thrombectomy-eligible LVOs]×100 = MT operator availability) and ([current MT centers×150/current annual number of estimated thrombectomy-eligible LVOs]×100= MT center availability). The metrics used optimal MT volume per operator as 50 and an optimal MT volume per center as 150. Multivariable-adjusted generalized linear models were used to evaluate factors associated with MTA. Results: We received 887 responses from 67 countries. The median global MTA was 2.79% (interquartile range, 0.70–11.74). MTA was <1.0% for 18 (27%) countries and 0 for 7 (10%) countries. There was a 460-fold disparity between the highest and lowest nonzero MTA regions and low-income countries had 88% lower MTA compared with high-income countries. The global MT operator availability was 16.5% of optimal and the MT center availability was 20.8% of optimal. On multivariable regression, country income level (low or lower–middle versus high: odds ratio, 0.08 [95% CI, 0.04–0.12]), MT operator availability (odds ratio, 3.35 [95% CI, 2.07–5.42]), MT center availability (odds ratio, 2.86 [95% CI, 1.84–4.48]), and presence of prehospital acute stroke bypass protocol (odds ratio, 4.00 [95% CI, 1.70–9.42]) were significantly associated with increased odds of MTA. Conclusions: Access to MT on a global level is extremely low, with enormous disparities between countries by income level. The significant determinants of MT access are the country’s per capita gross national income, prehospital LVO triage policy, and MT operator and center availability.