Scout Scanning

For localization of the coronary arteries and for identification of the period of minimal myocardial motion, 3 scout scans are recommended:

Scout 1: A low resolution 2D SSFP scan that covers the chest in 3 orthogonal views (coronal, sagittal, transverse). Multiple (10) 1 cm thick slices per view. The scan is performed during free-breathing.

Scout 2: On a mid-ventricular level (as identified on the first scout), a transverse 2D SSFP cine scan with 40 frames/s is acquired for the visual identification of the diastolic rest period. This scan can either be performed during free-breathing using signal averaging (total duration ~40 sec) or during one breath-hold of ~10 sec.

Scout 3: Transverse 3D SSFP scout scan for localization of the coronary arteries. Image acquisition is performed in late diastole, at the time-point of minimal myocardial motion as identified in Scout 2. The 3D volume of Scout 3 includes the whole heart including the apex and the pulmonary artery as seen on the coronal view of Scout 1. The navigator is localized at the dome of the right hemidiaphragm. Localization of the dome of the right hemidiaphragm is performed on the transverse and coronal views of Scout 1. The end-expiratory gating window for Scout 3 is 7 mm. The scan duration is ~ 1.5-2 min depending on the heart rate and the respiratory pattern of the patient (Table 1).

For high resolution coronary MRA, 3D volume-targeted SSFP or segmented k-space gradient echo imaging sequences are currently preferred. In the following protocols a compromise between bandwidth for signal-readout and TR was made. Therefore, not all the protocols run with the shortest possible TR values. Shortening of the TR is possible but at the cost of a reduced SNR (Table 2).

Table 3. Targeted coronary MRA. High-resolution free-breathing navigator gated and corrected 3D TFE

Parameter

Value

Unit

Parameter

Value

Unit

Field of View

270

mm

T2Prep/TE

YES/50

ms

Matrix

384

FatSat

YES

Slices

10

SENSE

NO

Slice Thickness

3.0

mm

Navigator

YES

Half Scan

NO

Gating Window

5

mm

TR

7.2

ms

Navigator Tracking

YES

TE

2.0 (Partial Echo)

ms

Tracking Factor

0.6

Tacq

71

ms

Bandwidth

135

Hz/Pixel

Alpha

25

Deg

Scan Duration

6-9

min

Spatial Resolution

0.7x1.0x3.0

mm3

Table 4. Whole-heart coronary MRA. High-resolution free-breathing navigator gated and corrected 3D SSFP

Parameter

Value

Unit

Parameter

Value

Unit

Field of View

256

mm

T2Prep/TE

YES/50

ms

Matrix

256

FatSat

YES

Slices

80

SENSE/Factor

YES/2

Slice Thickness

1.5

mm

Navigator

YES

Half Scan

NO

Gating Window

7

mm

TR

5.0

ms

Navigator Tracking

YES

TE

2.5

ms

Tracking Factor

0.6

Tacq

125

ms

Bandwidth

543

Hz/Pixel

Alpha

90

Deg

Scan Duration

10-15

min

Spatial Resolution

1.0x1.0x1.5

mm3

Essentials of Human Physiology

Essentials of Human Physiology

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