Cardiac cine MRI: Quantification of the relationship between fast gradient echo and steady-state free precession for determination of myocardial mass and volumes.

PURPOSE: To determine the correlation function between the steady-state free precession (SSFP) and fast gradient echo (FGRE) cine MRI pulse sequences for measuring the myocardial mass and volumes. MATERIALS AND METHODS: Cardiac cine MRI examinations were acquired in 50 individuals (female: 35, male: 15, mean age 64.1 +/- 9.1 years, range 48-83) using SSFP and FGRE cardiac pulse sequences. RESULTS: The mean (standard deviation [SD]) left ventricular end diastolic volume measured by SSFP was significantly larger (4.5%) than by FGRE (P < 0.001); this was also the case for end systolic volume (15.0%, P < 0.001). The relationship between SSFP and FGRE measures were linear and highly correlated (P < 0.001) for both left ventricular end diastolic and end systolic volumes (r(2) = 0.90 vs. 0.91, respectively). We determined linear regression models to estimate the SSFP values based on the FGRE measures. Slope (intercept) for ejection fraction, stroke volume, and cardiac output were 0.99 (-2.79), 0.77 (17.5), and 0.76 (1.29), respectively. CONCLUSION: Linear relationships exist for key LV function parameters when comparing SSFP and FGRE cine MRI. These results indicate that existing databases and normal values for FGRE LV function may be converted to corresponding LV function values for SSFP MRI.

Sonographic evaluation of optic nerve diameter in children with raised intracranial pressure.

OBJECTIVE: The optic nerve is part of the central nervous system, and a rise in intracranial pressure (ICP) can directly affect the perioptic nerve space, leading to an increase in nerve diameter. Transorbital sonography is a safe and easy-to-perform method to measure optic nerve diameter for rapid diagnosis of increased ICP. METHODS: The optic nerve diameter was measured in 3 individual occasions by transorbital sonography in the transverse view, 3 mm posterior to the papilla in both eyes, and the mean was calculated. Two groups were examined: a control group of children with normal ICP and normal ophthalmologic and optic nerve examination results and a case group with increased ICP as determined by an alternative method. RESULTS: The sample consisted of 156 children, of which 78 (50%) were in the case group and 78 (50%) were in the control group. Eighty-four subjects (53.7%) were male, and 72 (46.1%) were female. The mean +/- SD ages were 6.9 +/- 5.6 years in the case group and 6.8 +/- 5.5 years in the control group. The mean optic nerve diameters were 5.6 +/- 0.6 mm (range, 4.55 +/- 0.7 to 7.6 +/- 0.6 mm) in the case group and 3.3 +/- 0.6 mm (range, 2 +/- 0.6 to 4.35 +/- 0.6 mm) in the control group. The difference in the means was significant at P < .001. CONCLUSIONS: Optic nerve diameter, measured by transorbital sonography, was significantly greater in pediatric patients with increased ICP compared with a control group. Transorbital sonography can be used to identify pediatric patients with raised ICP.