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Biomedical subjects

K M Jones

Publications and source records attributed to K M Jones.

65 records · Page 4Linked to original sources
PubMedDate not supplied

Fast spin-echo imaging of intracranial neoplasms.

Our goal was to compare dual echo fast SE (FSE) T2-weighted MRI of intracranial neoplasms with conventional SE (CSE) images. In phase 1 of the study, CSE and FSE dual echo MR studies of 33 patients with intracranial neoplasms and 26 normal controls were separately interpreted by three neuroradiologists blinded to clinical history to ascertain differences in lesion conspicuity. The CSE and FSE images were read independently, in random order, with at least a 3 week interval between readings. In phase 2 of the study, CSE and FSE sequences were compared side by side by three neuroradiologists independently to evaluate lesion conspicuity and artifacts and to determine whether FSE would be an acceptable replacement for CSE imaging. Lesion detection was equivalent in 111 of 117 interpretations (94.9%). The CSE and FSE sequences were equivalent in detecting lesion-associated abnormalities (hemorrhage, calcium, mass effect, edema, and hydrocephalus) and in characterizing lesion size, margins, and signal intensity. Nonspecific T2 white matter hyperintensities were detected more often with CSE, while susceptibility artifacts were less conspicuous on FSE. Ventricular catheters, postoperative soft tissue and bony changes, and postradiation therapy changes were detected equally well on both sequences. In phase 2 of the study, lesion conspicuity and presence of artifacts were felt to be equivalent with the two sequences. The FSE sequences can serve as a rapid, feasible alternative to conventional CSE sequences for intracranial tumor detection.

Adolescent↗
PubMedDate not supplied

Rapid MR imaging of the pediatric brain using the fast spin-echo technique.

PURPOSE: To evaluate diagnostic reliability and to establish optimal scanning techniques of a recently developed Fast Spin-echo MR pulse sequence that allows rapid proton density-weighted and T2-weighted imaging. METHODS: We compared lesion conspicuity and signal intensity measurements on Fast Spin-echo and conventional spin-echo sequences in 81 patients ranging from 1 week to 25 years in age on a 1.5-T MR unit. A total of 28 Fast Spin-echo dual-echo images (14 slice locations) were obtained in 2:08 minutes with a 256 x 128 matrix or in 3:12 minutes with a 256 x 192 matrix at a TR of 2000 msec and two excitations. RESULTS: Lesion conspicuity and characterization on Fast Spin-echo images compared favorably with conventional spin-echo images in our series when pseudo-TEs of 15 and 90 msec were employed for proton density-weighted and T2-weighted images, respectively. Fast Spin-echo images yielded diagnostic information in four nonsedated patients whose conventional spin-echo images were either degraded by motion or unobtainable. Fat signal remained bright on T2-weighted Fast Spin-echo images. Magnetic-susceptibility effects were slightly reduced with Fast Spin-echo but did not pose any diagnostic problem in our series. CONCLUSION: Diagnostically reliable rapid dual-echo brain images can be obtained with Fast Spin-echo sequences.

Adolescent↗
PubMedDate not supplied

Pharmacokinetics of amiloride after inhalation and oral administration in adolescents and adults with cystic fibrosis.

STUDY OBJECTIVE: To compare the pharmacokinetics and systemic exposure of nebulized and oral amiloride in adolescents and adults with mild to moderate cystic fibrosis (CF). DESIGN: Open-label, randomized, two-way crossover, single-dose pharmacokinetic study. SETTING: University hospital clinical research unit. PATIENTS: Nine adolescents and 10 adults with mild to moderate CF (forced expiratory volume in 1 sec > or = 50% predicted, Brasfield score > or = 15). INTERVENTIONS: Patients received amiloride solution orally (10 mg of amiloride 1-mg/ml solution) and by inhalation [4.5 ml amiloride of 1-mg/ml solution in 12% saline (approximately 3.8 mmol/L) by DeVilbiss 646 nebulizer] during two study phases separated by a 7- to 28-day washout period. Serial blood and urine samples were collected for 48 and 72 hours, respectively. MEASUREMENTS AND MAIN RESULTS: After oral dosing, the mean +/- SD maximum peak concentration (Cmax) was 20.6 +/- 10.0 ng/ml at 3.2 +/- 1.2 hours in adults and 21.7 +/- 4.88 at 2.9 +/- 0.6 hours in the adolescents. Mean area under the concentration-time curve (AUC) from time zero to infinity hours was 275 +/- 115 and 254 +/- 60 ng.hr/ml in the adult and adolescent groups; half-life was 16.0 +/- 0.7 and 13.4 +/- 1.4 hours, respectively. After nebulization, 14 of 19 subjects exhibited two concentration peaks (Cmax1 and Cmax2) with mean values of 1.57 +/- 1.67 ng/ml at 0.5 +/- 0.2 hours and 1.37 +/- 1.21 ng/ml at 4.0 +/- 1.0 hours for adults, and 1.49 +/- 0.99 ng/ml at 0.5 +/- 0.1 hours and 1.52 +/- 0.81 ng/ml at 3.3 +/- 0.5 hours for adolescents. Estimated mean +/- SD dose nebulized was 1.91 +/- 0.66 and 2.28 +/- 0.30 mg in the adult and adolescent groups, respectively. Mean +/- SD AUC from time zero to the last measurable plasma amiloride concentration after inhalation was 14.4 +/- 17.6 and 15.4 +/- 10.1 ng.hr/ml in the adults and adolescents. No significant adverse events occurred during the study. Pharmacokinetic parameters were not statistically different between the adolescent and adult groups by route of administration. However significant differences in peak amiloride concentration, AUC, and urinary amiloride excretion were evident when comparing oral versus inhalation administration within each group. CONCLUSIONS: Mean amiloride plasma concentration peaks and AUC after inhalation were significantly lower than after oral dosing. In addition, the second amiloride plasma concentration peak may be due to oral ingestion of the nebulized amiloride, whereas the earlier Cmax1 after inhalation may be due to pulmonary absorption of amiloride. These results suggest that single-dose amiloride inhalation in patients with mild to moderate CF results in minimal systemic exposure compared with oral dosing, and that drug disposition is similar in adolescents and adults with CF.

Administration, Inhalation↗