Contrast circulation in adult fontan patients using MR Time Resolved Angiography: Application for CT pulmonary angiography.

BACKGROUND: When patients with Fontan circulation require a computed tomographic pulmonary angiogram (CTPA), there are significant challenges in achieving adequate contrast opacification due to the altered anatomical connections. This study used Time Resolved Angiography with Interleaved Stochastic Trajectories (TWIST) Magnetic Resonance Angiography (MRA) to examine contrast circulation in a cohort of patients with Fontan circulation who were having routine MRI follow up to inform the contrast timing of any subsequent CT. METHODS: This is a single centre, cross-sectional, observational, retrospective study. The time to peak (TTP) signal intensity from the MRA was recorded using regions of interest on the aorta, pulmonary arteries, cavae and Fontan conduit. Patients were grouped by ejection fraction, global longitudinal strain, indexed stroke volume and cardiac index to examine if these cardiac performance parameters affected the mean TTP. Statistical analysis was performed to find the mean TTP for each of the vessels, which was consequently compared between the different cardiac performance parameters. RESULTS: 35 patients were included in the study. Mean TTP contrast enhancement was 31s in the thoracic aorta, 46s in the right pulmonary artery, 41s in the left pulmonary artery and 55s in the Fontan conduit. Cardiac performance shows no statistically significant relationship to the peak contrast enhancement whether measured by ejection fraction, global longitudinal strain, stroke volume index or cardiac index. CONCLUSION: The mean optimal timing for a single-phase examination of the Fontan circulation, following an upper limb injection, was 55 s following start of contrast injection irrespective of cardiac performance. In TWIST MRA, the IV bolus is 4-5 s duration. A longer bolus is required for CTA, around 20s, suggesting an additional delay will be required. We propose that an optimal single phase CTPA to be protocolled at 70 s following the start of contrast injection, assuming adequate iodinated contrast dose.

Multimodality cardiac imaging of submitral left ventricular aneurysm with concurrent descending aorta mycotic aneurysm.

We present a case of a 20-year-old Malay man with underlying tuberculous (TB) lymphadenitis who presented with shortness of breath and found to have submitral left ventricular aneurysm (SLVA). SLVA is well recognised but rare. Incidence of SLVA in Malay has never been documented. This is the first reported case of SLVA in Malays with concomitant thoracic aorta mycotic aneurysm. TB has been reported to be associated with SLVA. Treatment is either surgical or conservative. Imaging is required for diagnosis and preoperative assessment. Multimodality imaging include echocardiography (ECHO), cardiac CTangiography and the robust multiparametric cardiac MR (CMR). ECHO is the first line imaging and useful for initial detection of the aneurysm. CMR including the late gadolinium enhancement allows excellent visualisation of the LV aneurysm, tissue characterisation, cardiac function and detection of associated pathology as shown in this case.