Table 1 The advantages, disadvantages, and techniques of different modalities for evaluation of PLSVC
From: Persistent left superior vena cava: clinical importance and differential diagnoses
Imaging modality | Pros | Cons | Techniques |
|---|---|---|---|
Echocardiography | ✓ Cheap ✓ Widely available ✓ No ionizing radiation ✓ Not affected by cardiac rhythm ✓ Portable (bedside assessment) ✓ Real-time imaging ✓ Enables evaluation of flow direction | Difficult to interpret Operator-dependent Acoustic window dependent The spatial resolution could be limited. | * Coexistence of dilated coronary sinus without any evidence of right-sided congestion and positive “Bubble study” are diagnostic sonographic findings for PLSVC. * “Bubble study” is conducted with the injection of agitated saline from the left peripheral arm veins. If PLSVC is present, the agitated saline bubbles firstly are seen in the coronary sinus, before the right atrium. * In case of isolated PLSVC, positive “Bubble study” is observed after injection from right peripheral arm veins, as well. * Contrast-enhanced echocardiography and transesophageal echocardiography are other useful modalities for the detection of PLSVC. |
Multidetector computed tomography | ✓ Accessible ✓ Fast scanning speed ✓ The best spatial resolution ✓ Enables multiplanar imaging and reformatting | Radiation exposure (Recently developed dose reduction methods have partially reduced concerns about radiation exposure.) An iodinated contrast agent (allergy, nephrotoxicity) Cardiac rhythm changes may cause artifacts. Need for sedation in the pediatric age group | * “ECG-gated CCTA with thin slices and multiplanar reformation” provides a detailed assessment. * “Intravenous non-ionic iodinated contrast injection with a dose of 0,5-2 ml/kg at a rate of 1-2 ml/s” is recommended. *The identification of PLSVC is usually independent of the contrast injection route (right or left, upper or lower extremities). The optimal contrast opacification of PLSVC is mostly seen in the delayed venous phase images. |
Magnetic resonance imaging | ✓ Radiation free ✓ High spatial resolution ✓ Enables multiplanar image acquisition ✓ Enables assessment of flow direction ✓ Depiction of PLSVC even without the administration of contrast media ✓ Non-iodinated contrast | High cost Less accessible Slow scanning speed Contraindications such as the magnetic implant, claustrophobia. Cardiac rhythm changes may cause artifacts. Need for sedation in the pediatric age group | * Axial and coronal cine SSFP sequences are the best sequences for imaging of PLSVC. * The black blood TSE T2 images is also useful. * Contrast-enhanced MRA (± Dynamic imaging) and phase contrast angiography can be used as auxiliary modalities. |
Invasive angiography | ✓ Gold standard ✓ Excellent morphologic information ✓ Interventions can be made if necessary | Invasive Radiation exposure An iodinated contrast agent (Allergy, nephrotoxicity) Need for sedation in the pediatric age group | * The catheter angiography with water-soluble contrast agent is performed. Venograms are obtained after bolus contrast injection from the catheter. * Invasive angiography is not a routine imaging modality for evaluation PLSVC. * PLSVC can be detected incidentally during procedures like central venous catheter insertion or pacemaker implantation. |