Magnetic microparticle aggregation for viscosity determination by MR

Micron‐sized magnetic particles were induced to aggregate when placed in homogeneous magnetic fields, like those of MR imagers and relaxometers, and then spontaneously returned to their dispersed state when removed from the field. Associated with the aggregation and dispersion of the magnetic particles were time‐dependent increases and decreases in the spin–spin relaxation time (T₂) of the water. Magnetic nanoparticles, with far smaller magnetic moments per particle, did not undergo magnetically induced aggregation and exhibited time‐independent values of T₂. The rate of T₂ change associated with magnetic microparticle aggregation was used to determine the viscosity of liquid samples, providing a method that can be of particular advantage for determining the viscosity of small volumes of potentially biohazardous samples of blood or blood plasma. Magn Reson Med 59:515–520, 2008. © 2008 Wiley‐Liss, Inc.     

Transabdominal versus endovaginal pelvic sonography: prospective study

Transabdominal and endovaginal pelvic sonograms were obtained in 108 nonpregnant patients referred for pelvic sonography. The studies were independently obtained by two radiologists and interpreted on the basis of identical clinical information. The sonograms were then compared for anatomic detail and abnormalities. A determination was made about which examination, if either, was superior. Follow-up was performed through a review of the medical records and follow-up studies. Overall, the endovaginal study was judged superior in 65 cases (60.2%), equal in 39 (36.1%), and inferior in four (3.7%). The authors conclude that the endovaginal examination can effectively replace the transabdominal examination as the initial approach for routine pelvic sonography.     

Sonographic findings in a case of tetrasomy 9p associated with increased nuchal translucency and Dandy‐Walker malformation

We report a case of a 23‐year‐old pregnant woman, who underwent amniocentesis after ultrasound (US) examination in the first trimester which revealed a nuchal translucency thickness of 2.9 mm. Cytogenetic analysis revealed complete tetrasomy of the short arm of chromosome 9. Further US evaluation in the second trimester revealed Dandy‐Walker malformation, ventriculomegaly, bilateral clubfoot, lip and palate clefts, arthrogryposis and hyperechoic kidneys with bilateral pelvic dilatation. At 30 weeks of gestation, a placental abruption was noted and a Cesarean section was performed. The infant died shortly after birth. A review of previous cases of tetrasomy 9p shows that the remarkable sonographic findings are ventriculomegaly, intrauterine growth restriction, genitourinary anomaly, Dandy‐Walker malformation, cleft lip/palate and limb malformation, but the association of tetrasomy 9p and increased nuchal translucency had not been reported. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound, 2009.     

Future directions in biomaterials

Biomaterials have made a great impact on medicine. However, numerous challenges remain. This paper discusses three representative areas involving important medical problems. First, drug delivery systems; major considerations include drug-polymer interactions, drug transformation, diffusion properties of drugs and, if degradation occurs, of polymer degradation products through polymer matrices developing a more complete understanding of matrix degradation in the case of erodible polymers and developing new engineered polymers designed for specific purposes such as vaccination or pulsatile release. Second, cell-polymer interactions, including the fate of inert polymers, the use of polymers as templates for tissue regeneration and the study of polymers which aid cell transplantation. Third, orthopaedic biomaterials, including basic research in the behaviour of chrondrocytes, osteocytes and connective tissue-free interfaces and applied research involving computer-aided design of biomaterials and the creation of orthopaedic biomaterials.     

Intravenous digital subtraction renal angiography: use in screening for renovascular hypertension

Intravenous digital subtraction renal angiography (DSRA) has been compared with conventional angiography only in small, selected series of hypertensive patients. The authors prospectively examined with intravenous DSRA 94 patients at increased risk for renovascular hypertension and compared these studies with conventional angiography. A stenosis of at least one main renal artery was identified with intravenous DSRA in 22 patients and confirmed in 20 patients. No significant stenoses were seen with conventional angiography in any of the 64 patients in whom lesions were not seen with intravenous DSRA. Since inadequate DSRA studies were considered positive for renal artery stenosis, the sensitivity of intravenous DSRA was 100% (25 of 25); specificity, 93% (64 of 69); positive predictive value, 83% (25 of 30); and negative predictive value, 100% (64 of 64). The authors conclude that intravenous DSRA is a sensitive test for identifying stenosis of the main renal arteries and is appropriate to use as a screening test among patients at increased risk for renovascular hypertension.