Demonstrated is a moderate secundum atrial septal defect (ASD) and a mild coarctation. MRI obtained for evaluation of distal arch and pulmonary veins due to findings of pulmonary overcirculation out of proportion to typical ASD pathophysiology.
MRI findings:
- Moderate secundum ASD; Qp:Qs of 2:1
- Mild right atrial, right ventricular, main pulmonary artery and branch PA enlargement
- LSVC drains to the right atrium via a dilated coronary sinus.
- No significant coarctation identified, however, there is distal displacement of the left subclavian artery
MRI images obtained at end-systole due to tachycardic heart rate during exam.
RV End-systolic volume is 14.13 ml.
LV End-systolic volume is 5.74 ml.
MRI methods:
A GE 1.5T HDxt system was used for the 3D HEART sequence which used a 3D respiratory-navigated balanced SSFP (steady state free precession) multi-slab sequence with T2 preparation that provides whole heart coverage with high contrast-to-noise ratio between vessels and myocardium. Due to the relatively fast heart rate of 120 bpm, the acquisition window was centered on the quiescent stage of end systole. The sequence was run with the following parameters: TR 4.3, TE 1.78, Freq 224, Phase 192, RR 8, and fat sat on.
Learning:
The MRI provided a complete anatomic overview and quantified the right sided enlargement from the 2:1 shunt through the ASD. Due to saturation band nulling of blood returning through the right sided pulmonary veins, there was excellent definition of the ASD due to the "dark" blood mixing with the "bright" blood and outlining the borders of the ASD which transfers to the model very well. Please keep in mind, that the model represents a heart in end-systole rather than diastole.
Disclaimer:
The available model has been validated to demonstrate the case’s pathologic features on a Z450 3D printer, (3DSystems, Circle Rock Hill, South Carolina)(or other printer as appropriate). While the mask applied to the original DICOM images accurately represents the anatomic features, some anatomic detail may be lost due to thin walled structures or inadequate supporting architecture; while other anatomic detail may be added due to similar limitations resulting in bleeding of modeling materials into small negative spaces. However, intracardiac structures, relationships, and pathologic features represent anatomic findings to scale and in high detail.
