MR imaging of surgical complications of systemic-to-pulmonary artery shunts

Role of MRI in clinical cardiology

Rapid progress has been made in cardiac MRI (CMRI) over the past decade, which has firmly established it as a reliable and clinically important technique for assessment of cardiac structure, function, perfusion, and myocardial viability. Its versatility and accuracy is unmatched by any other individual imaging modality. CMRI is non-invasive and has high spatial resolution and avoids use of potentially nephrotoxic contrast agent or radiation. It has been extensively studied against other established non-invasive imaging modalities and has been shown to be superior in many scenarios, particularly with respect to assessment of cardiac and great vessel morphology and left ventricular function. Furthermore, its clinical use continues to expand with increasing experience and proliferation of CMRI centres. As worldwide prevalence of cardiovascular disease continues to rise, CMRI provides opportunity for improved and cost-effective non-invasive assessment. Continued progress in CMRI technology promises to further widen its clinical application in coronary imaging, myocardial perfusion, comprehensive assessment of valves, and plaque characterisation.

Development of a perigraft seroma around modified Blalock-Taussig shunts: imaging evaluation

OBJECTIVE

The modified Blalock-Taussig shunt is a synthetic shunt between the subclavian and pulmonary artery, frequently used in the treatment of children with pulmonary hypoperfusion caused by congenital heart disease. The development of a perigraft seroma is a known complication of this procedure. We sought to describe the imaging features of a perigraft seroma and to define an optimal diagnostic strategy in patients with a suspected perigraft seroma.

MATERIALS AND METHODS

Between January 1993 and December 1998, 96 children underwent 105 modified Blalock-Taussig shunt procedures. In eight children, 11 cases of perigraft seromas were identified. The mean age of these children at the time of operation was 3 years (range, 6 days to 5 years 8 months). Pre- and postoperative chest radiographs were routinely performed in the children in whom seromas had been found. Additional postoperative radiologic investigations consisted of thoracic sonography (in 11 cases), CT (in eight cases), and MR imaging (in two cases). In all cases of perigraft seroma, the modified Blalock-Taussig shunts were constructed through a posterolateral thoracotomy at the fourth intercostal space.

RESULTS

On average, the chest radiographs showed the first signs of the seroma on day 10 after the surgery (range, day 1-day 30). Using thoracic sonography, it was possible to visualize the perigraft seroma and the modified Blalock-Taussig shunt in eight (73%) of 11 cases. CT and MR imaging performed equally well in revealing perigraft seromas.

CONCLUSION

As was found in these critically ill children, sonography has an advantage over CT and MR imaging because of its portability and, therefore, capability for bedside use. We recommend the use of sonography as the initial imaging modality in suspected cases of perigraft seroma development.

Morphologic and functional evaluation of congenital heart disease by magnetic resonance imaging

Magnetic resonance imaging (MRI) has evolved sufficiently to be recognized as a useful complementary noninvasive method to echocardiography in the evaluation of congenital heart disease (CHD). In some cases, MRI is superior to other imaging modalities, particularly in the evaluation of thoracic aortic anomalies and in defining the anatomy of central pulmonary arteries; it is also the procedure of choice in the postoperative follow-up of patients with CHD. Recent technological advances permit not only morphological evaluation (provided by spin-echo and MR angiographic techniques) but functional and flow information (provided by fast cine-GE and velocity-encoded sequences), causing it to be recognized by pediatric cardiologists and cardiac surgeons as an unavoidable technique for pre- and postoperative evaluation of some CHD. This review describes the various techniques used in the evaluation of CHD with emphasis on recent developments as well as recognized clinical applications. J. Magn. Reson. Imaging 1999;10:639-655.

Cardiac MR imaging in congenital heart disease

Magnetic resonance imaging is a unique and insightful tool for the assessment of structure and function in congenital heart disease. For anatomic assessment, the large field of view, lack of limitation by patient size, and ability to create three-dimensional surface displays from routine imaging acquisitions offer several advantages over other modalities. The ability of magnetic resonance imaging to assess the volume and mass of bizarre ventricular shapes accurately and myocardial tissue and blood tagging as well as phase encoded velocity mapping has enhanced research in pediatric cardiology. Newer techniques, such as oxygen-sensitive magnetic resonance imaging and echo-planar magnetic resonance imaging, promise even further advances in research and in clinical applications.