title: Splenic T1-mapping: a novel quantitative method for assessing adenosine stress adequacy for cardiovascular magnetic resonance.
abstract: BACKGROUND
  Perfusion cardiovascular magnetic resonance (CMR) performed with inadequate adenosine stress leads to false-negative results and suboptimal clinical management. The recently proposed marker of adequate stress, the "splenic switch-off" sign, detects splenic blood flow attenuation during stress perfusion (spleen appears dark), but can only be assessed after gadolinium first-pass, when it is too late to optimize the stress response. Reduction in splenic blood volume during adenosine stress is expected to shorten native splenic T1, which may predict splenic switch-off without the need for gadolinium.
  
  
  METHODS
  Two-hundred and twelve subjects underwent adenosine stress CMR: 1.5 T (n = 104; 75 patients, 29 healthy controls); 3 T (n = 108; 86 patients, 22 healthy controls). Native T1spleenwas assessed using heart-rate-independent ShMOLLI prototype sequence at rest and during adenosine stress (140 μg/kg/min, 4 min, IV) in 3 short-axis slices (basal, mid-ventricular, apical). This was compared with changes in peak splenic perfusion signal intensity (ΔSIspleen) and the "splenic switch-off" sign on conventional stress/rest gadolinium perfusion imaging. T1spleenvalues were obtained blinded to perfusion ΔSIspleen, both were derived using regions of interest carefully placed to avoid artefacts and partial-volume effects.
  
  
  RESULTS
  Normal resting splenic T1 values were 1102 ± 66 ms (1.5 T) and 1352 ± 114 ms (3 T), slightly higher than in patients (1083 ± 59 ms, p = 0.04; 1295 ± 105 ms, p = 0.01, respectively). T1spleendecreased significantly during adenosine stress (mean ΔT1spleen~ -40 ms), independent of field strength, age, gender, and cardiovascular diseases. While ΔT1spleencorrelated strongly with ΔSIspleen(rho = 0.70, p < 0.0001); neither indices showed significant correlations with conventional hemodynamic markers (rate pressure product) during stress. By ROC analysis, a ΔT1spleenthreshold of ≥ -30 ms during stress predicted the "splenic switch-off" sign (AUC 0.90, p < 0.0001) with sensitivity (90%), specificity (88%), accuracy (90%), PPV (98%), NPV (42%).
  
  
  CONCLUSIONS
  Adenosine stress and rest splenic T1-mapping is a novel method for assessing stress responses, independent of conventional hemodynamic parameters. It enables prediction of the visual "splenic switch-off" sign without the need for gadolinium, and correlates well to changes in splenic signal intensity during stress/rest perfusion imaging. ΔT1spleenholds promise to facilitate optimization of stress responses before gadolinium first-pass perfusion CMR.
authors.affiliation: Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Alexander
authors.initials: A
authors.lastname: Liu
authors.affiliation: Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Rohan S
authors.initials: RS
authors.lastname: Wijesurendra
authors.affiliation: Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Rina
authors.initials: R
authors.lastname: Ariga
authors.affiliation: Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Masliza
authors.initials: M
authors.lastname: Mahmod
authors.affiliation: Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Eylem
authors.initials: E
authors.lastname: Levelt
authors.affiliation: Siemens Healthcare GmbH, Erlangen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Greiser
authors.affiliation: Department of Cardiothoracic Surgery, John Radcliffe Hospital, Oxford, UK.
authors.forename: Mario
authors.initials: M
authors.lastname: Petrou
authors.affiliation: Department of Cardiothoracic Surgery, John Radcliffe Hospital, Oxford, UK.
authors.forename: George
authors.initials: G
authors.lastname: Krasopoulos
authors.affiliation: Oxford Heart Centre, John Radcliffe Hospital, Oxford, UK.
authors.forename: John C
authors.initials: JC
authors.lastname: Forfar
authors.affiliation: Oxford Heart Centre, John Radcliffe Hospital, Oxford, UK.|Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Rajesh K
authors.initials: RK
authors.lastname: Kharbanda
authors.affiliation: Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Keith M
authors.initials: KM
authors.lastname: Channon
authors.affiliation: Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Stefan
authors.initials: S
authors.lastname: Neubauer
authors.affiliation: Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
authors.forename: Stefan K
authors.initials: SK
authors.lastname: Piechnik
authors.affiliation: Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK. Vanessa.ferreira@cardiov.ox.ac.uk.
authors.forename: Vanessa M
authors.initials: VM
authors.lastname: Ferreira
mesh_terms: D000241:Adenosine / Q000008:administration & dosage*; D000328:Adult; D000368:Aged; D019540:Area Under Curve; D016022:Case-Control Studies; D003287:Contrast Media / Q000008:administration & dosage; D003326:Coronary Circulation; D005188:False Negative Reactions; D005260:Female; D005682:Gadolinium / Q000008:administration & dosage; D006331:Heart Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D013152:Splanchnic Circulation; D013154:Spleen / Q000098:blood supply* / Q000000981:diagnostic imaging*; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D003287:Contrast Media; D014665:Vasodilator Agents; D005682:Gadolinium; D000241:Adenosine
keywords: Adenosine stress; Cardiovascular magnetic resonance; ShMOLLI; Splenic T1; Switch-off