Splenic Switch-off: A Tool to Assess Stress Adequacy in Adenosine Perfusion Cardiac MR Imaging.
OBJECTIVE
To investigate the pharmacology and potential clinical utility of splenic switch-off to identify understress in adenosine perfusion cardiac magnetic resonance (MR) imaging.


METHODS
Splenic switch-off was assessed in perfusion cardiac MR examinations from 100 patients (mean age, 62 years [age range, 18-87 years]) by using three stress agents (adenosine, dobutamine, and regadenoson) in three different institutions, with appropriate ethical permissions. In addition, 100 negative adenosine images from the Clinical Evaluation of MR Imaging in Coronary Heart Disease (CE-MARC) trial (35 false and 65 true negative; mean age, 59 years [age range, 40-73 years]) were assessed to ascertain the clinical utility of the sign to detect likely pharmacologic understress. Differences in splenic perfusion were compared by using Wilcoxon signed rank or Wilcoxon rank sum tests, and true-negative and false-negative findings in CE-MARC groups were compared by using the Fisher exact test.


RESULTS
The spleen was visible in 99% (198 of 200) of examinations and interobserver agreement in the visual grading of splenic switch-off was excellent (κ = 0.92). Visually, splenic switch-off occurred in 90% of adenosine studies, but never in dobutamine or regadenoson studies. Semiquantitative assessments supported these observations: peak signal intensity was 78% less with adenosine than at rest (P < .001), but unchanged with regadenoson (4% reduction; P = .08). Calculated peak splenic divided by myocardial signal intensity (peak splenic/myocardial signal intensity) differed between stress agents (adenosine median, 0.34; dobutamine median, 1.34; regadenoson median, 1.13; P < .001). Failed splenic switch-off was significantly more common in CE-MARC patients with false-negative findings than with true-negative findings (34% vs 9%, P < .005).


CONCLUSIONS
Failed splenic switch-off with adenosine is a new, simple observation that identifies understressed patients who are at risk for false-negative findings on perfusion MR images. These data suggest that almost 10% of all patients may be understressed, and that repeat examination of individuals with failed splenic switch-off may significantly improve test sensitivity.
From the Heart Hospital Imaging Centre, University College London, 16-18 Westmoreland St, London W1G 8PH, England (C.M., A.S.H., G.C., J.C.M.); Multidisciplinary Cardiovascular Research Centre and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, England (D.P.R., S.P., J.P.G.); Department of Medicine (T.C.W., E.B.S.) and UPMC Cardiovascular Magnetic Resonance Center (E.B.S.), University of Pittsburgh School of Medicine, Pittsburgh, Pa; NIHR Cardiovascular Biomedical Research Unit, Barts Health NHS Trust and Queen Mary University of London, London, England (S.E.P.); and Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, Southampton, England (C.P.).
Charlotte
C
Manisty
From the Heart Hospital Imaging Centre, University College London, 16-18 Westmoreland St, London W1G 8PH, England (C.M., A.S.H., G.C., J.C.M.); Multidisciplinary Cardiovascular Research Centre and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, England (D.P.R., S.P., J.P.G.); Department of Medicine (T.C.W., E.B.S.) and UPMC Cardiovascular Magnetic Resonance Center (E.B.S.), University of Pittsburgh School of Medicine, Pittsburgh, Pa; NIHR Cardiovascular Biomedical Research Unit, Barts Health NHS Trust and Queen Mary University of London, London, England (S.E.P.); and Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, Southampton, England (C.P.).
David P
DP
Ripley
From the Heart Hospital Imaging Centre, University College London, 16-18 Westmoreland St, London W1G 8PH, England (C.M., A.S.H., G.C., J.C.M.); Multidisciplinary Cardiovascular Research Centre and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, England (D.P.R., S.P., J.P.G.); Department of Medicine (T.C.W., E.B.S.) and UPMC Cardiovascular Magnetic Resonance Center (E.B.S.), University of Pittsburgh School of Medicine, Pittsburgh, Pa; NIHR Cardiovascular Biomedical Research Unit, Barts Health NHS Trust and Queen Mary University of London, London, England (S.E.P.); and Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, Southampton, England (C.P.).
Anna S
AS
Herrey
From the Heart Hospital Imaging Centre, University College London, 16-18 Westmoreland St, London W1G 8PH, England (C.M., A.S.H., G.C., J.C.M.); Multidisciplinary Cardiovascular Research Centre and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, England (D.P.R., S.P., J.P.G.); Department of Medicine (T.C.W., E.B.S.) and UPMC Cardiovascular Magnetic Resonance Center (E.B.S.), University of Pittsburgh School of Medicine, Pittsburgh, Pa; NIHR Cardiovascular Biomedical Research Unit, Barts Health NHS Trust and Queen Mary University of London, London, England (S.E.P.); and Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, Southampton, England (C.P.).
Gabriella
G
Captur
From the Heart Hospital Imaging Centre, University College London, 16-18 Westmoreland St, London W1G 8PH, England (C.M., A.S.H., G.C., J.C.M.); Multidisciplinary Cardiovascular Research Centre and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, England (D.P.R., S.P., J.P.G.); Department of Medicine (T.C.W., E.B.S.) and UPMC Cardiovascular Magnetic Resonance Center (E.B.S.), University of Pittsburgh School of Medicine, Pittsburgh, Pa; NIHR Cardiovascular Biomedical Research Unit, Barts Health NHS Trust and Queen Mary University of London, London, England (S.E.P.); and Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, Southampton, England (C.P.).
Timothy C
TC
Wong
From the Heart Hospital Imaging Centre, University College London, 16-18 Westmoreland St, London W1G 8PH, England (C.M., A.S.H., G.C., J.C.M.); Multidisciplinary Cardiovascular Research Centre and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, England (D.P.R., S.P., J.P.G.); Department of Medicine (T.C.W., E.B.S.) and UPMC Cardiovascular Magnetic Resonance Center (E.B.S.), University of Pittsburgh School of Medicine, Pittsburgh, Pa; NIHR Cardiovascular Biomedical Research Unit, Barts Health NHS Trust and Queen Mary University of London, London, England (S.E.P.); and Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, Southampton, England (C.P.).
Steffen E
SE
Petersen
From the Heart Hospital Imaging Centre, University College London, 16-18 Westmoreland St, London W1G 8PH, England (C.M., A.S.H., G.C., J.C.M.); Multidisciplinary Cardiovascular Research Centre and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, England (D.P.R., S.P., J.P.G.); Department of Medicine (T.C.W., E.B.S.) and UPMC Cardiovascular Magnetic Resonance Center (E.B.S.), University of Pittsburgh School of Medicine, Pittsburgh, Pa; NIHR Cardiovascular Biomedical Research Unit, Barts Health NHS Trust and Queen Mary University of London, London, England (S.E.P.); and Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, Southampton, England (C.P.).
Sven
S
Plein
From the Heart Hospital Imaging Centre, University College London, 16-18 Westmoreland St, London W1G 8PH, England (C.M., A.S.H., G.C., J.C.M.); Multidisciplinary Cardiovascular Research Centre and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, England (D.P.R., S.P., J.P.G.); Department of Medicine (T.C.W., E.B.S.) and UPMC Cardiovascular Magnetic Resonance Center (E.B.S.), University of Pittsburgh School of Medicine, Pittsburgh, Pa; NIHR Cardiovascular Biomedical Research Unit, Barts Health NHS Trust and Queen Mary University of London, London, England (S.E.P.); and Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, Southampton, England (C.P.).
Charles
C
Peebles
From the Heart Hospital Imaging Centre, University College London, 16-18 Westmoreland St, London W1G 8PH, England (C.M., A.S.H., G.C., J.C.M.); Multidisciplinary Cardiovascular Research Centre and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, England (D.P.R., S.P., J.P.G.); Department of Medicine (T.C.W., E.B.S.) and UPMC Cardiovascular Magnetic Resonance Center (E.B.S.), University of Pittsburgh School of Medicine, Pittsburgh, Pa; NIHR Cardiovascular Biomedical Research Unit, Barts Health NHS Trust and Queen Mary University of London, London, England (S.E.P.); and Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, Southampton, England (C.P.).
Erik B
EB
Schelbert
From the Heart Hospital Imaging Centre, University College London, 16-18 Westmoreland St, London W1G 8PH, England (C.M., A.S.H., G.C., J.C.M.); Multidisciplinary Cardiovascular Research Centre and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, England (D.P.R., S.P., J.P.G.); Department of Medicine (T.C.W., E.B.S.) and UPMC Cardiovascular Magnetic Resonance Center (E.B.S.), University of Pittsburgh School of Medicine, Pittsburgh, Pa; NIHR Cardiovascular Biomedical Research Unit, Barts Health NHS Trust and Queen Mary University of London, London, England (S.E.P.); and Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, Southampton, England (C.P.).
John P
JP
Greenwood
From the Heart Hospital Imaging Centre, University College London, 16-18 Westmoreland St, London W1G 8PH, England (C.M., A.S.H., G.C., J.C.M.); Multidisciplinary Cardiovascular Research Centre and Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds, England (D.P.R., S.P., J.P.G.); Department of Medicine (T.C.W., E.B.S.) and UPMC Cardiovascular Magnetic Resonance Center (E.B.S.), University of Pittsburgh School of Medicine, Pittsburgh, Pa; NIHR Cardiovascular Biomedical Research Unit, Barts Health NHS Trust and Queen Mary University of London, London, England (S.E.P.); and Wessex Cardiothoracic Unit, Southampton University Hospitals NHS Trust, Southampton, England (C.P.).
James C
JC
Moon
D000241:Adenosine; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D057791:Cardiac Imaging Techniques / Q000379:methods*; D004280:Dobutamine; D005080:Exercise Test / Q000379:methods*; D006801:Humans; D018810:Magnetic Resonance Angiography; D008875:Middle Aged; D010477:Perfusion; D011687:Purines; D011720:Pyrazoles; D012189:Retrospective Studies; D013154:Spleen / Q000502:physiology*; D055815:Young Adult
D011687:Purines; D011720:Pyrazoles; C430916:regadenoson; D004280:Dobutamine; D000241:Adenosine