Splenic T1-mapping: a novel quantitative method for assessing adenosine stress adequacy for cardiovascular magnetic resonance

Abstract

BackgroundPerfusion 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.MethodsTwo-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 T1spleen was 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. T1spleen values were obtained blinded to perfusion ΔSIspleen, both were derived using regions of interest carefully placed to avoid artefacts and partial-volume effects.ResultsNormal 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). T1spleen decreased significantly during adenosine stress (mean ΔT1spleen ~ −40 ms), independent of field strength, age, gender, and cardiovascular diseases. While ΔT1spleen correlated 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 ΔT1spleen threshold 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%).ConclusionsAdenosine 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. ΔT1spleen holds promise to facilitate optimization of stress responses before gadolinium first-pass perfusion CMR.Electronic supplementary materialThe online version of this article (doi:10.1186/s12968-016-0318-2) contains supplementary material, which is available to authorized users.

INCA (Peru) Study: Impact of Non‐Invasive Cardiac Magnetic Resonance Assessment in the Developing World

“…The clinical utility found in Peru of 56% having changed care after CMR is somewhat less than demonstrated in international registries, as European/US registries have reported that CMR changed care in 61.8% of patients 30, 31. However, we would have reached these levels in our study by including the 5% of patients in which a change in management was appropriate but not possible due to access barriers.…”

Factors Determining Inadequate Stress Response to Adenosine Triphosphate in Perfusion Cardiovascular Magnetic Resonance

“…Low body weight was shown to be another independent 048 Predictor for inadequate stress is low body weight (p=0.02) and male gender (p=0.019). SBP: systolic blood pressure, HR: heart rate adenosine dosage up-titrations before contrast injection, thereby improving the quality of stress response before first-pass perfusion imaging [27]. One disadvantage of this methodology is the extra time required for T1-mapping.…”

“…One future strategy is to measure real time splenic flow directly during adenosine-induced stress before contrast administration, which would ensure that perfusion images are acquired only when an adequate stress response is achieved. From Liu et al [27], the delta T1 of the spleen can facilitate optimization of stress responses before gadolinium first-pass perfusion CMR. This enables prediction of the visual SSO sign without the need for gadolinium.…”

Are you stressed?

“…15 The problem that the switch-off sign can only be seen following contrast media application has been overcome by using a native T1-mapping technique for the quantification of tissue blood volumes without contrast application. 16 The splenic reaction to adenosine stress may thus be used to monitor and guide the dose of adenosine application. In one study, 74 of 955 patients did not respond to standard adenosine administration (140 mg/kg/min).…”