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Biomedical subjects

Charles McKenzie

Publications and source records attributed to Charles McKenzie.

5 recordsLinked to original sources
PubMed2006

Three-dimensional T1 mapping for dGEMRIC at 3.0 T using the Look Locker method.

OBJECTIVE: The objective of this study was to implement a three-dimensional (3-D) T1 mapping sequence (3DLL) at 3.0 T for dGEMRIC based on the Look Locker scheme. MATERIALS AND METHODS: Because all current reports on dGEMRIC are at 1.5 T and mostly using 2-D IR fast spin echo (FSE), data were acquired at 1.5 T and 3.0 T with both 3DLL and 2-D IR-FSE sequence. Phantoms with different concentrations of Gd(DTPA) were used and seven subjects (three asymptomatic, four symptomatic) were scanned using the dGEMRIC technique. RESULTS: The T1 measurements obtained on the phantom with 3DLL show very good agreement with those acquired with 2-D IR-FSE. Using a two-tailed paired t test, the T1 (Gd) measurements in two sections obtained in all subjects with both sequences were found to be statistically indistinguishable at either field strength (P = 0.07 at 1.5 T and P = 0.07 at 3.0 T). CONCLUSIONS: The preliminary data presented here suggest that the 3DLL sequence provides accurate T1 values with sufficient in-plane resolution and allows full joint coverage in less than 10 minutes.

Adult↗
PubMed2005

Real-time magnetic resonance imaging aids prenatal diagnosis of isolated cleft palate.

OBJECTIVE: Cleft of the secondary palate without cleft lip is difficult to visualize sonographically. This study was performed to assess the utility of sonography, standard magnetic resonance (MR) imaging, and real-time MR imaging in the diagnosis of isolated cleft palate. METHODS: We prospectively assessed 5 fetuses at risk for isolated cleft palate on the basis of family history, micrognathia, or both, using sonography and standard and real-time single-shot fast spin echo MR sequences. Written informed consent was obtained under our Institutional Review Board-approved Health Insurance Portability and Accountability Act-compliant protocol. Images were assessed for confidence in a diagnosis of cleft or normal palate. Prenatal and postnatal diagnoses were compared. RESULTS: In 3 fetuses, micrognathia was visualized by sonography and MR imaging with standard and real-time sequences. One fetus at 19 weeks had a wide cleft of the entire secondary palate, and another fetus at 33 weeks had a cleft of the soft palate; these defects were seen only with real-time MR imaging. One 35-week gestational age fetus had a cleft soft palate that was visualized on standard and real-time MR imaging. Two fetuses with no abnormalities had the normal midline secondary palate seen only on real-time MR imaging. In all fetuses, real-time images were helpful in assessing the secondary palate because the entire midline naso-oropharynx could be visualized. CONCLUSIONS: Real-time MR imaging allows for rapid assessment of the midline structures, providing accurate diagnosis of isolated cleft palate.

Cleft Palate↗
PubMed2004

Glycosaminoglycan distribution in cartilage as determined by delayed gadolinium-enhanced MRI of cartilage (dGEMRIC): potential clinical applications.

OBJECTIVE: We sought to describe a range of in vivo observations of glycosaminoglycan distribution in knee cartilage using the delayed gadolinium-enhanced MRI of cartilage technique. CONCLUSION: The index of glycosaminoglycan distribution, T1(Gd), can exceed 500 msec (denoting high glycosaminoglycan) or can be less than 300 msec, with focal areas as low as 240 msec. Compartmental differences, as well as focal defects within the knee, were observed in patients who had sustained injuries to the ligaments and menisci of the knee or who had chronic osteoarthritis. Overall, these results suggest the need for further research into the biochemical changes seen during disease progression and the effects of therapeutic interventions.

Adult↗
PubMed2003

Tips and tricks of fetal MR imaging.

The technique of performing fetal MR examinations differs from routine pelvic MR imaging because the fetus is in motion, and image planes must be selected orthogonal to fetal anatomy. The small size of the fetus also increases examination difficulty because thin slices (limited by SNR) are often needed for adequate examination of anatomy and pathology. Knowledge of fetal anatomy and neonatal anatomy/ pathology are needed in the assessment of fetal MR imaging. Knowledge of MR artifacts aids in image interpretation.

Artifacts↗