Pulmonary MR Angiography

Pulmonary MR Angiography

Sagittal Oblique Coronal MIP

Martin R. Prince

with slides borrowed from

Tom Grist, MDJorg Debatin, MDJim Meaney, MDPiotr Wielopolski, PhDQian Dong, MDRuth Carlos, MDDavid Stafford-Johnson, MDStefan Schoenberg, MDGus Bis, MDVic Ferarri, MDStefan Reuhm, MD

Pulmonary Embolism• > 600,000 per year

• 30% mortality

• Difficult to diagnosis• V/Q - 64% indeterminate

• Angio is expensive + risks

• CTA safer but nephrotoxicity

• Anticoagulation: 7% risk of

major complication

MR Angiography Protocol• Coronal 3D Volume

• image both lungs simutaneously• large dose of Gd

(<180 lb 2 bottles, 42ml)(>180 lb 3 bottles, 63ml)

• one injection

• Sagittal 3D Volumes• small FOV, no wrap• two separate injections • main PA excluded

Coronal 3D Gd:MRA

Pulmonary MRA Technique

• Sagittal Locator 1 min

• Coronal 3D Volume x 3 1.5 min

Total imaging time <3 min

Prescribing Coronal 3D Volume• Posterior to spinal cord

• Anterior to the ascending aorta

• Large FOV to prevent wrap

• No spoiling

• Fast scan for breath holding• Thick slices: 3-5 mm• Zero interpolation (ZIP x 2)• Gradient upgrade for short TR• Partial Fourier Imaging

• Multiphase

Injecting the Gadolinium• 2 ml/sec (as fast as you can)• 6-10 second scan delay for arterial phase• equilibrium phase• rest to catch breath • equilibrium phase again • ventilated patient: suspend in max inspiration

Arterial Phase Equilibrium Phase

Acute Pulmonary Embolism

Chronic Pulmonary Embolism

Pulmonary Embolism:Diagnosis with MRA

Author Year # of pt Techniques Sensitivity Specificity

Grist 1993 20 TOF 92% 63%

Isoda 1995 18 3D Gd 80% 95%

Laissy 1995 28 TOF + Gd 87% 95%

Wolff 1996 34 2D Gd 72% 94%

Meaney 1997 30 3D Gd 87% 97%

Gupta 1999 36 3D Gd 85% 96%

Diagnosis of Pulmonary Embolism* with MRA (n=30)

1 2 3

Sensitivity 100% 87% 75%

Specificity 95% 100% 95%

*Meaney et al. NEJM 366:1422-7, 1997.

Diagnosis of Pulmonary Embolism* with MRA (n=36)

Reviewer 1 2

Sensitivity 92% 77% Specificity 83% 91%PPV 75% 83%NPV 95% 88%*Gupta et al Radiology 1999; 210:353-359

Shortness of Breath with cough in a 51-year-old female

Coronal MIP

Magnification

Reformation

Partial anomlous pulmonary venous return from the right upper lobe

Coronal MIP

Magnification

Reformation

46-year-old female with machinery murmur

Axial T1

Patent Ductus Arteriosus

Axial T1

Pulmonic stenosis

Blood pool agent MRA

Summary• 3D Gd:MRA useful

• Safeno nephrotoxicityno ionizing radiationno arterial catheterization

• Fast (30 second breath hold)

• Accurate

• Better with blood pool?