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					                Stress MRI
What is its role and Is It Practical?
  Mouaz Al-Mallah, MD MSc FACC FAHA FESC
   Associate Professor of Medicine, Wayne State University, Detroit, USA
                Director,
                Director Advanced Cardiovascular Imaging
                      King Abdul Aziz Cardiac Center
                          Riyadh, Saudia Arabia
 5 Things You Need to Know About
    Magnetic Resonance Imaging
• The magnet is ALWAYS ON
• No ionizing radiation
• MR contrast agents are not nephrotoxic
   – Contraindication in chronic renal failure because of
       p g         y                 (
     nephrogenic systemic fibrosis (NSF)  )
   – Excellent soft tissue contrast even without contrast
      y                                   g g
• Body habitus does not interfere with imaging if the
  patient can just fit! Most magnets accommodate 350-
  400 lbs
• Nearly 10% of patinets are claustrophobic , So ask
  your patient!!!!!!!
72 yo man with exertional chest tightness
      and mild SOB over 3 months
T.C.

Cath:

mLAD 70%
RCA prox total with collaterals
Dom prox LCx total with collaterals
Dobutamine combined Cine Function and
         Perfusion P t
         P f i Protocol   l




            Rest and
Localize     Stress        Perfusion     Recovery    Delayed Imaging
            Function

             Progressive stages of          15 min        10 min
      Dobutamine + atropine stress (20 min)
   Dobutamine MRI Protocol
                                    Atropine 0.5 mg,
                                  repeat 0.25 q minute
                                      40

                             30

                        20

                   10

 Dobutamine    5
    dose
(mcg/kg/min)
               0   3    6    9       12      15
Time (min)
BP
ECG

                                                  CP985547-9
      y
 Safety of Dobutamine Stress MRI
• 1,000 consecutive DCMR tests over 5 years
                       evidence
• More than 50% had e idence of ischemia
• 10 side effects occurred in 6.4%
  –      t i d      ti l t h         di      ti t)
      sustained ventricular tachycardia (1 patient)s   0 1%
                                                       0.1%
  –   nonsustained ventricular tachycardia             0.4%
  –   paroxysmal atrial fibrillation                   1.6%
                                                       1 6%
  –   transient second degree AV block 2:1             0.2%
  –                          (
      Severe increase in BP (>240/120 mmHg)   g)       0.5%
  –   decrease in systolic BP >40 mmHg                 0.5%
  –   nausea                                           3.1%

                                                      2004;25:1230–
                                          Eur Heart J 2004;25:1230–1236
 Use of Dobutamine Cine MRI for
      Detection f I h i
      D t ti of Ischemia
 N = 172      DSE       DSMR P value
Sensitivity   74.3%       86.2%      <0.05

Specificity   69.8%       85.7%      <0.05

              81 0%
              81.0%       91.3%
                          91 3%      <0.05
                                     <0 05
    PPV
              61.1%       78.3%      <0.05
    NPV
 Accuracy     72.7%       86.0%      <0.05



                      Nagel E et al. Circulation 1999
             Diagnostic Accuracy of
                Dobutamine
                D b t i MRI
   h
Author         Year   n        Sensitivity Specificity A
                               S i i i S ifi i         Accuracy
Pennell       1992    25          91%
Baer
B             1994    26          85%
Van Ruggee    1994    39          91%        80%         90%
Nagel         1999    172         86%        86%         86%
Hundley       1999    41          83%        83%         83%
Paetsch       2004    79          89%        80%         86%
Wahl          2004    160         89%        84%         88%



                            Adapted from CV MRI Kwong et al., 2008
         Prognostic Value Dobutamine MRI
               p       ,          q     y
           279 patients, Poor DSE quality




Multivariate Predictors of all cause mortality or   Hundley et al. Circulation 2002
CV death/MI were EF and ischemia
        MRI Vasodilator Perfusion
                             FPMP                              FPMP
  C di
  Cardiac                                  R i l
                                           Regional               t
                                                                 at               Delayed
                            During
localization                               Function             Rest            Enhancement
                          vasodilating
                             stress




               Saturation Prep
                      i                   SSFP Imaging                          MDE
               EPI-fgre FPMP             Short/Long Axis                        Gd-DTPA
                                                           Matching SAX views
               1 R-R                                                            (accumulative
               3-4 SAX views                                                    0.15 mmol/Kg)
               Gd-DTPA 0.05-
               0.075mmol/kg
               at 5 ml/sec
80 year old lady with chest pain, SOB
STRESS




REST
 Dynamic First Pass Perfusion Exam
           Regional Defects Indicate Ischemia

   LAD

   RCA

   LCX                                      Mid




                                            Apex
    Base




          t    i            t    i
LAD 100% stenosis, RCA 60% stenosis
Perfusion Quality Control
 Is th b l ti ht        h?
 I the bolus tight enough?




                  Bad Bolus:
Good Bolus        • Leaky IV
                  • Slow injection rate
                  • Low ejection fraction
                  • Pulmonary disease
                  • Intracardiac shunt
                    Semi-quantitative MR Perfusion
                   300

                   250
          ensity




                                                           LV signal
                   200
  gnal Inte




                                                                                Occluded
                   150                                                           region
                                                     Normal region
                   100
Sig




                   50
                                                 Occluded region
                                                                            Normal
                    0                                                       region
                         0   5   10   15   20   25    30     35   40   45

                                      Time (seconds)
        Diagnostic Accuracy
   patients
47 patients, 33 Without Known CAD
                         Sensitivity   Specificity    Accuracy
           Overall          87%           89%           82%
           1V Disease      100%           94%           96%

           2V Disease       71%           83%           75%
           Grafts          100%           75%           90%


                         Sensitivity Specificity     Accuracy
           DE              48%           94%            76%
           Cine            74%           93%            86%
           Stress perf     81%           90%            87%
           Ab
           Above 3         89%           88%            88%

                               Cury et al., Radiology 2006; 240:39–45
     p
Interpretation of MRI Perfusion

                        Sensitivity   Specificity   Accuracy
          Algorithm        89%           87%          88%
          Perfusion        84%           58%          63%
          Cine             49%           73%          63%
          DE               49%           98%          78%




                                                 2006;47:1630-
                  Klem et al., J Am Coll Cardiol 2006;47:1630-8
Schwitter et al., Eur Heart J 2008;29:480–489
Schwitter et al., Eur Heart J 2008;29:480–489
Diagnostic
Performance
of CMR vs.
all SPECT
and gated
SPECT




Schwitter et al., Eur Heart J 2008;29:480–489
Schwitter et al., Eur Heart J 2008;29:480–489
Prognostic Value of Perfusion MRI




Bodi et al., JACC 2007;50:1174–9   Jahnke et al., Circulation.
                                     2007;115:1769-
                                     2007;115:1769-1776.
              Perfusion MRI at 3T
      Saturation-recovery spoiled gradient-echo
        101 patients, Prevalence of CAD 69%

                       Sensitivity        Specificity               Accuracy
  Patient-based            90%                71%                       84%
  Vessel-based             76%                89%                       86%
  LAD                      83%                86%                       85%

  LCX                      75%                91%                       88%

  RCA                      68%                91%                       85%

In 24% of patients without DE, dark rim artifacts
were detected, mostly in the LAD territory (56%)
                                              Gebker et al Radiology: Vol 247: 1 April 2008
               Dark Rim Artifact




Subendocardial perfusion defect during A, stress and B,
rest in absence of scar (C) at DE. Patient had no relevant
ste os s coronary angiography.
stenosis at co o a y a g og ap y

                                   Gebker et al Radiology: Vol 247: 1 April 2008
            Perfusion MRI at 3T

• 61 patients referred for elective coronary
  angiography
• Patients underwent Adenosine perfusion MRI at
                                   p
  1.5T ad 3T
• Four short-axis images were acquired during
  every heartbeat using a saturation recovery fast-
  gradient echo sequence and 0.04 mmol/kg Gd-
  DTPA bolus injection
  Qualitative Perfusion      l i by blinded
• Q lit ti P f i analysis b 2 bli d d
  readers
• The prevalence of CAD was 66%
                            Cheng et al., J Am Coll Cardiol 2007;49:2440–9)
       Perfusion MRI at 3T
61 patients, 66% CAD prevalence
              1.5 T                            3T
          y
Sensitivity   90%                             98%
Specificity   67%                             78%
PPV           84%                             89%
NPV           78%                             94%
Accuracy      82%                             78%

                      Cheng et al., J Am Coll Cardiol 2007;49:2440–9)
      Perfusion MRI at 3T
Diagnostic Accuracy: 1V Disease
              1.5 T                            3T
          y
Sensitivity   68%                             90%
Specificity   71%                             88%
PPV           52%                             77%
NPV           83%                             95%
Accuracy      71%                             89%

                      Cheng et al., J Am Coll Cardiol 2007;49:2440–9)
              Perfusion MRI at 3T
  Diagnostic Accuracy: Multi-vessel Diseases

                    1.5 T                            3T
          y
Sensitivity         71%                             95%
Specificity         93%                             95%
PPV                 83%                             91%
NPV                 86%                             97%
Accuracy            85%                             95%

                            Cheng et al., J Am Coll Cardiol 2007;49:2440–9)
 Advantages of Perfusion MR
  The bili        b i i bili       df     i d f
• Th ability to obtain viability and function data from
  one test that can be performed in 1 – 1.5 hrs

• Possible superior performance in multivessel disease
  p                   (
  patients vs. SPECT (balanced ischemia in SPECT as
  high as 11% in some series)

• Lack of radiation
Disadvantages of Perfusion MR
• Higher cost and limited availability

• Limits on Gad dosing in CKD patients

                                     holding
• More difficult on patients (breath holding,
  claustrophobia)

• Newer kid on the block (learning curve)

				
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