Comparison of 3 T and 1.5 T for T2* magnetic resonance of tissue iron.

BACKGROUND: T2* magnetic resonance of tissue iron concentration has improved the outcome of transfusion dependant anaemia patients. Clinical evaluation is performed at 1.5 T but scanners operating at 3 T are increasing in numbers. There is a paucity of data on the relative merits of iron quantification at 3 T vs 1.5 T. METHODS: A total of 104 transfusion dependent anaemia patients and 20 normal volunteers were prospectively recruited to undergo cardiac and liver T2* assessment at both 1.5 T and 3 T. Intra-observer, inter-observer and inter-study reproducibility analysis were performed on 20 randomly selected patients for cardiac and liver T2*. RESULTS: Association between heart and liver T2* at 1.5 T and 3 T was non-linear with good fit (R (2) = 0.954, p < 0.001 for heart white-blood (WB) imaging; R (2) = 0.931, p < 0.001 for heart black-blood (BB) imaging; R (2) = 0.993, p < 0.001 for liver imaging). R2* approximately doubled between 1.5 T and 3 T with linear fits for both heart and liver (94, 94 and 105 % respectively). Coefficients of variation for intra- and inter-observer reproducibility, as well as inter-study reproducibility trended to be less good at 3 T (3.5 to 6.5 %) than at 1.5 T (1.4 to 5.7 %) for both heart and liver T2*. Artefact scores for the heart were significantly worse with the 3 T BB sequence (median 4, IQR 2-5) compared with the 1.5 T BB sequence (4 [3-5], p = 0.007). CONCLUSION: Heart and liver T2* and R2* at 3 T show close association with 1.5 T values, but there were more artefacts at 3 T and trends to lower reproducibility causing difficulty in quantifying low T2* values with high tissue iron. Therefore T2* imaging at 1.5 T remains the gold standard for clinical practice. However, in centres where only 3 T is available, equivalent values at 1.5 T may be approximated by halving the 3 T tissue R2* with subsequent conversion to T2*

Color Doppler imaging of retrobulbar circulation in glaucoma

Blood flow velocities and resistance indices of ophthalmic (OA), central retinal (CRA) and temporal short posterior ciliary arteries (TSPCA) were evaluated with color Doppler imaging (CDI) in patients with primary open angle glaucoma (POAG) and normotensive glaucoma (NTG). End-diastolic and peak systolic velocities of CRA and TSPCA were significantly lowered in both glaucoma groups (p < 0.05), and resistance indices significantly raised (p < 0.05). Impaired retrobulbar circulation seems to play an important role in the development of glaucomatous optic nerve damage, and CDI is an easy, non-invasive and reproducible method in evaluating such patients

Diode laser cyclophotocoagulation in refractory glaucoma: Comparison between pediatric and adult glaucomas

OBJECTIVE: To evaluate the outcome of contact transscleral diode laser cyclophotocoagulation (CTDC) in eyes with advanced glaucoma and to compare the efficacy in pediatric and adult patients

The effects of beta-blockers on ocular blood flow in patients with primary open angle glaucoma: a color doppler imaging study

PURPOSE. TO evaluate the effects of four commonly used beta-blockers on ocular blood flow in patients with primary open angle glaucoma (POAG)