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?