Diagnosis of patent foramen ovale using maximum intensity T-projection imaging

Accurate diagnosis of patent foramen ovale (PFO) and grading of right-to-left shunt severity by the standard method of transthoracic or transesophageal echocardiography (TEE) with bubble injection is often challenging. We proposed the novel Maximum Intensity T-Projection (MIP) Imaging method as a complementary or alternative approach for simplified diagnosis and grading of PFO. MIP Imaging represents the superimposition of all frames of an echocardiographic video onto one image. Thus, all bubbles passing from right to left atrium are represented in this single image. Diagnosis and quantification of PFO by MIP Images were compared to those obtained by standard echocardiographic methods, using the same echocardiography video loops. We applied the MIP Imaging approach to 122 echo examinations (75% of them TEE studies), performed to rule out PFOs. The average time needed to manually analyze video loops taken during bubble injection was 102 ± 52 s vs. less than 1 s using the MIP Imaging method. There was good concordance between the conventional echo method and MIP Imaging in the diagnosis and quantification of PFOs. MIP Imaging for diagnosis and quantification of PFOs was much less time consuming than the classical method and at least as accurate as the classical method. Thus MIP Imaging may be used initially as an adjunct method for PFO diagnosis and quantification and may eventually replace the classical method.