How We Do CMR How We Do CMR PerfusionPerfusion

Robert Manka, Rolf Gebker, Eike Robert Manka, Rolf Gebker, Eike NagelNagel

German Heart Institute Berlin and

www.cmr-academy.com

Created October 2007 for SCMRCreated October 2007 for SCMRThis presentation posted for members of scmr as an This presentation posted for members of scmr as an

educational guide – it represents the views and practices of the educational guide – it represents the views and practices of the author, and not necessarily those of SCMR. author, and not necessarily those of SCMR.

How we do Perfusion

PerfusionPerfusion The occurrence of myocardial perfusion The occurrence of myocardial perfusion

deficits is a very sensitive indicator of deficits is a very sensitive indicator of ischemia in the presence of significant ischemia in the presence of significant coronary artery stenoses.coronary artery stenoses.

Most perfusion defects occur during Most perfusion defects occur during stress, such as pharmacological stress, such as pharmacological vasodilation.vasodilation.

Adenosine is a safe and well tolerated Adenosine is a safe and well tolerated pharmacologicalpharmacological stress agent. stress agent.

In-plane resolution of 2-3 mm allows In-plane resolution of 2-3 mm allows separate visualization of the endo- and separate visualization of the endo- and epicardial layers of the left ventricle. epicardial layers of the left ventricle.

How we do Perfusion

Pharmacological AgentPharmacological Agent Stressor agent:Stressor agent:

1.1. AdenosineAdenosine: i.v. : i.v. 140 mcg/kg/min 140 mcg/kg/min (preferable concentration 5mg/ml) (preferable concentration 5mg/ml)- A- A potent vasodilator of most vascular beds, except for potent vasodilator of most vascular beds, except for hepatic and renal arterioles. It exerts its hepatic and renal arterioles. It exerts its pharmacological effect through the activation of pharmacological effect through the activation of purine A1 and A2 cell-surface adenosine receptorspurine A1 and A2 cell-surface adenosine receptors- Half-life 4-10 seconds- Half-life 4-10 seconds

Antidote: Antidote: 1.1. Adenosine infusion should be discontinued Adenosine infusion should be discontinued 2.2. Aminophylline i.v (250mg slowly injected under ECG Aminophylline i.v (250mg slowly injected under ECG

monitoring)monitoring)

Patient instruction: Patient instruction: 1.1. No caffeine (tea, coffee, chocolate)No caffeine (tea, coffee, chocolate)2.2. No aminophyline or nitrates for 24 hoursNo aminophyline or nitrates for 24 hours

How we do Perfusion

Adenosine- Side-EffectsAdenosine- Side-Effects Mild-to-moderate reduction in systolic, diastolic and Mild-to-moderate reduction in systolic, diastolic and

mean arterial blood pressure (< 10 mmHg) with a mean arterial blood pressure (< 10 mmHg) with a reflex increase in heart rate. reflex increase in heart rate.

Some patients complain about chest pain, which is Some patients complain about chest pain, which is rather nonspecific and does not reliably indicate the rather nonspecific and does not reliably indicate the presence of CAD. presence of CAD.

Direct depressant effect on the SA and AV nodes Direct depressant effect on the SA and AV nodes transient first-, second- and third-degree AV block transient first-, second- and third-degree AV block and sinus bradycardia have been reported in 2.8%, and sinus bradycardia have been reported in 2.8%, 4.1% and 0.8% of patients.4.1% and 0.8% of patients.

Increases in minute ventilation, reduction in arterial Increases in minute ventilation, reduction in arterial PCO2 and respiratory alkalosis. PCO2 and respiratory alkalosis.

Approximately 14% of patients complain of dyspnea. Approximately 14% of patients complain of dyspnea.

How we do Perfusion

Contraindications/Contraindications/TerminationTermination

Contraindication for Contraindication for AdenosineAdenosine Myocardial infarction <3 Myocardial infarction <3

DaysDays Unstable angina pectorisUnstable angina pectoris Asthma or severe obstruktive Asthma or severe obstruktive

pulmonary diseasepulmonary disease AV-block >IIaAV-block >IIa ClaustrophobiaClaustrophobia Non compatible biometallic Non compatible biometallic

implants (pacemaker/AICD)implants (pacemaker/AICD)

Caution Caution Stenotic valvular diseaseStenotic valvular disease Autonomic dysfunctionAutonomic dysfunction Cerebrovascular Cerebrovascular

insufficiencyinsufficiency

Termination criteriaTermination criteria Persistent or Persistent or

symptomatik AV-blocksymptomatik AV-block Significant drop in Significant drop in

systolic pressure (>20 systolic pressure (>20 mmHg)mmHg)

Persistent or Persistent or symptomatic symptomatic hypotensionhypotension

Severe respiratory Severe respiratory difficultydifficulty

How we do Perfusion

Scanner environmentScanner environment

The pts lies in the supine position The pts lies in the supine position 1.5 or 3 Tesla (T) whole body 1.5 or 3 Tesla (T) whole body

scannerscanner Gradient strength 30 mT/m, Gradient strength 30 mT/m,

slew rate 150 mT/m/ms slew rate 150 mT/m/ms 5 element cardiac synergy coil5 element cardiac synergy coil Multichannel ECG (Vector-ECG)Multichannel ECG (Vector-ECG)

How we do Perfusion

Contrast Agents and Contrast Agents and Injection SchemeInjection Scheme

Bolus with a dosage of Bolus with a dosage of 0.05 mmol/kg bw0.05 mmol/kg bw of an extracellular Gd-based CA (dose may of an extracellular Gd-based CA (dose may be lower with Gd-DTPA-BMA) be lower with Gd-DTPA-BMA)

Injection speed of Injection speed of 4 ml/s4 ml/s is used at the is used at the German Heart Institute BerlinGerman Heart Institute Berlin

The bolus is followed by a The bolus is followed by a 20 ml saline 20 ml saline flushflush using the same injection rate to using the same injection rate to facilitate a compact bolus passagefacilitate a compact bolus passage

We recommend the use of an We recommend the use of an automatic automatic infusion system infusion system

Two 18 gauge venflonsTwo 18 gauge venflons for separate for separate administration of the stress agent and CA administration of the stress agent and CA

How we do Perfusion

Imaging ProcedureImaging Procedure

Cine wall motion imaging of the heart at Cine wall motion imaging of the heart at restrest, , perfusion imaging under perfusion imaging under vasodilator stressvasodilator stress, and , and finally finally delayed enhancementdelayed enhancement imaging imaging

Examination time may vary between 40-75 minutes Examination time may vary between 40-75 minutes Breathhold should be performed duringBreathhold should be performed during expiration expiration to to

ensure reproducible slice geometry ensure reproducible slice geometry First is a about First is a about 6 to 10 seconds6 to 10 seconds during baseline acquisition during baseline acquisition

of myocardial signal intensity. of myocardial signal intensity. Then the patient is asked to inhale and exhale once more Then the patient is asked to inhale and exhale once more

and to hold his breath as long as possible. Right before and to hold his breath as long as possible. Right before starting this breathhold command the contrast bolus is starting this breathhold command the contrast bolus is administered. administered.

The patient should stop breathing at least for The patient should stop breathing at least for 15 to 20 15 to 20 secondsseconds resulting in a fixed slice geometry during the first- resulting in a fixed slice geometry during the first-pass of the contrast agent pass of the contrast agent

How we do Perfusion

Survey(1) Transversal(2) Single-angulated view(3) Double-angulated view

Resting wall motion(4) Short axis (apical, mid, basal slice)(5) 4 chamber/3 chamber(6) 2 chamber

Perfusion test scan(7) Slice geometry identical to (4)

acquisition of 5 dynamic images

Stress Perfusion(8) Start imaging (60 dynamics) after

4 minutes of adenosine infusion

Rest Perfusion(9) Repeat (8) without adenosine

infusion

Adenosine infusion (140 µg/kg/min)over 4 minutes

Carefully exclude any wraparoundIf necessary enlarge field of view

Stop adenosine infusion

Inject gadolinium 0.05 mmol/kg

RR

, rhyth

m &

resp

irato

ry m

on

itorin

g

Delayed Enhancement(10) Determine optimal inversion time

Inject gadolinium 0.05 mmol/kg

Inject gadolinium 0.1 mmol/kg

wait 10 min

wait 10 min

Perfusion Perfusion FlowchartFlowchart

How we do Perfusion

2nd breathhold

scanning interval

Baseline 5 dyn,

start contrast injection

contrast injection

1st breathh

old

start scan

free breathing

First pass myocardial

contrast uptake

LV contrast uptake

RV contrast uptake: 2nd breath hold command

Second pass myocardial

contrast uptake

Scanning procedureScanning procedure

1 breathing

cycle

How we do Perfusion

Pulse SequencesPulse Sequences

1.1. T1-weightedT1-weighted

2.2. In-plane resolution of 2-3 mmIn-plane resolution of 2-3 mm to to separately visualize the endo- and separately visualize the endo- and epicardial layers.epicardial layers.

3.3. We use a We use a balanced SSFP-techniquebalanced SSFP-technique which shows a higher peak which shows a higher peak enhancement and superior image enhancement and superior image quality compared with other quality compared with other sequences (T1-GrE, GrE-EPI).sequences (T1-GrE, GrE-EPI).

How we do Perfusion

Monitoring requirementsMonitoring requirements

1.1. Heart rate & rhythm: continuouslyHeart rate & rhythm: continuously

2.2. Blood pressure: every minuteBlood pressure: every minute

3.3. Pulse oximetry: not required when Pulse oximetry: not required when the vector-ECG usedthe vector-ECG used

4.4. Symptoms: Symptoms: continuouslycontinuously

5.5. DefibrillatorDefibrillator

6.6. All medications for emergency All medications for emergency treatmenttreatment

How we do Perfusion

Analysis of MR Perfusion Analysis of MR Perfusion StudiesStudies

cover 16 out of 17 myocardial segments cover 16 out of 17 myocardial segments Visual AnalysisVisual Analysis

For routine clinical use, we do a qualitative analysis by visual comparison of the contrast enhancement in different myocardial regions (see next slide)

QuantitativeQuantitative Absolute Tissue Perfusion (Unit: ml/g/min)

(requires mathematical modeling) Semiquantification

(stress induced change of upslope)

How we do Perfusion

Visual assessment of assessment of regional myocardial regional myocardial

perfusion perfusion

Abnormalities:Abnormalities:

Signal intensity Pattern and LocationSignal intensity Pattern and Location Dark regions arising from the subendocardium with usually irregular Dark regions arising from the subendocardium with usually irregular

intramyocardial border or with completely transmural extent.intramyocardial border or with completely transmural extent.

Dynamic myocardial filling patternDynamic myocardial filling patternInitially, slow or missing enhancement persistent over a few dynamics with Initially, slow or missing enhancement persistent over a few dynamics with consecutive signal intensity increase starting from the defects epicardial consecutive signal intensity increase starting from the defects epicardial border.border.

Comparison Stress vs. RestComparison Stress vs. Rest If a regional defect is found in the stress scan, but not in the rest scan, If a regional defect is found in the stress scan, but not in the rest scan,

inducible ischemia is confirmed. Regional persistence of the perfusion deficit inducible ischemia is confirmed. Regional persistence of the perfusion deficit shows myocardial scar.shows myocardial scar.

Evaluate the equatorial slice first, then check whether the suspected perfusion defect Evaluate the equatorial slice first, then check whether the suspected perfusion defect can be followed in corresponding segments of the apical or basal slicecan be followed in corresponding segments of the apical or basal slice

How we do Perfusion

ReportReport Data is reported for 16/17 segments (segment 1 – 16). Data is reported for 16/17 segments (segment 1 – 16).

The apical segment (17) is not visualized with 3 short The apical segment (17) is not visualized with 3 short axis views.axis views.

Perfusion defects are reported with their transmurality Perfusion defects are reported with their transmurality (transmural defect vs. subendocardial defect).(transmural defect vs. subendocardial defect).

Perfusion images are compared to cine and late Perfusion images are compared to cine and late enhancement imagesenhancement images

How we do Perfusion

Stress-Perfusion

Baseline Early mycardialcontrast uptake

RV contrastuptake

Late myocardialcontrast uptake

How we do Perfusion

Stress-Perfusion

Rest-Perfusion

Baseline LV contrastuptake

RV contrastuptake

Myocardialcontrast uptake

Viability andcoronaryangiography