Left ventricular noncompaction syndrome, a cardiomyopathy characterized by deep trabeculations in the ventricular wall, is typically diagnosed by echocardiography. However, according to research published this month in the American Journal of Roentgenology, echocardiography may not visualize the apical region optimally, leading to underestimation of the degree of the disease.
“Recent cardiac MRI reports suggest a ratio of noncompacted myocardium to compacted myocardium of >2.3 yields the highest sensitivity (86 percent) and specificity (99 percent) in diagnosis,” the authors wrote.
Researchers from the department of radiology’s cardiac MR-PET-CT program at Massachusetts General Hospital and Harvard Medical School in Boston conducted a retrospective blinded study of 19 patients with cardiac MRI. Nine patients presented with a diagnosis of left ventricular noncompaction on the basis of clinical and echocardiographic findings. A cohort of 10 control subjects with normal global and regional left ventricular function also underwent cardiac MRI for comparative purposes.
“The hypothesis of the current study was that cardiac MRI may detect trabecular delayed hyperenhancement in a series of patient with left ventricular noncompaction and that the amount and degree of trabecular delayed hyperenhancement might be useful in quantifying the clinical stage of the disease,” the authors wrote.
All patients in the study had a cardiac MRI performed on a 1.5-Tesla system using an eight-element phased-array cardiac coil for signal reception. The scientists obtained left ventricular function with cine images using a steady-state free precession technique in two-chamber, four-chamber, and short-axis planes.
After baseline imaging was performed, a delayed hyperenhancement MRI was conducted using an inversion recovery prepared gated fast gradient-echo pulse sequence, 10 to 12 minutes after a bolus injection of gadopentetate dimeglumine. According to the authors, delayed hyperenhancement images were acquired to optimally show normal myocardium and trabeculae and regions of delayed hyperenhancement with the myocardium and trabeculae with the proper selection of varying inversion time (T1) values. (See Figure 1)
The images were interpreted by a cardiac radiologist who was blinded to the diagnosis and clinical severity of the cases. To determine left ventricular noncompaction, segmental analysis was evaluated, although the apex segment was excluded because it is normally thin and may lead to false-positive interpretations, the authors noted.
Cine short-axis images were evaluated using Simpson’s method for calculation of ejection fraction, end-diastolic volume, end-systolic volume, and myocardial mass. Ventricular wall motion abnormalities were defined, and regional wall motion was scored on a 5-point scale. In addition, the distribution of noncompacted to compacted myocardium was quantitatively analyzed. (See Figure 2)
The researchers measured the degree of trabecular delayed hyperenhancement by placing a region of interest in the trabeculae and a second region of interest in the middle myocardium of the corresponding myocardial segment at the same ventricular level. This process was conducted for each of 16 cardiac segments, and a ratio of trabecular to myocardial signal was calculated.
“We defined trabecular delayed hyperenhancement as present when the ratio of trabecular to corresponding myocardial signal intensity was ≥ 3 <,” the authors wrote. (See Figure 3)
The scientists reported that for severity of left ventricular noncompaction, there were statistically significant differences in the anterior, anterolateral, and inferolateral segments among all clinical stage groups at the mid level and for all segments at the apical level. They found that for the extent of left ventricular noncompaction, there were statistically significant differences in the anterior, anterolateral, inferolateral, and inferior segments among all clinical stage groups at the mid level and for all segments at the apical level.
They noted that there were statistically significant differences among all clinical stage groups at the mid level in the inferior segment and the anterior, lateral, and septal segment at the apical level for the degree of trabecular delayed hyperenhancement. Their research uncovered statistically significant differences