Work in progress: the application of temporal filtering techniques to hybrid subtraction in digital subtraction angiography

Temporal filtering methods were applied to iodine signal-to-noise ratio (SNR) restoration in intravenous hybrid subtraction digital subtraction angiography (DSA). For equal detected exposure rates hybrid subtraction had approximately 35% of the SNR of temporal subtraction. When matched filtering was applied to a DSA run, the filtered result had approximately two times higher SNR than the peak contrast image in the run. Thus, when matched filtering techniques were applied to the hybrid image sequence, the resultant SNR increased to about 70% of that of temporal subtraction. With an additional factor-of-two increase in exposure rate for the hybrid run, SNR parity with temporal subtraction could be achieved. This compared with a factor-of-nine increase in exposure that would be required if no filtering were performed. Experimental hybrid matched filter results, generated with intravenous canine DSA studies, supported the predictions in SNR performance.     

Risk-stratified nosocomial infection surveillance in a neonatal intensive care unit: Report on 24 months of surveillance

Objective : To document the nosocomial infection rate in a single neonatal intensive care unit (NICU) in terms of patient workload and device utilization.
Methodology : Nosocomial infections have been identified and documented by the methodology described by the National Nosocomial Infection Surveillance System (NNIS), Centres for Disease Control, Atlanta. In addition, antibiotic usage has been surveyed in the NICU and standardized measures of patient exposure to antibiotics stratified by birthweight and gestational age have been described.
Results : Overall nosocomial infection rates compared favourably with the published NNIS figures at 6.2 infections per 100 admissions or 4.8 per 1000 patient days. Infection rates were significantly higher in lower birthweight groups. Device-related infection rates in each birthweight cohort were also very close to published figures and varied less with birthweight group. Antibiotic exposure averaged 12% of total admission days, less than previously published data.
Conclusions : The NNIS system is applicable to Australian NICU and provides an effective tool for monitoring infection episodes.     

消旋棉酚拆分的研究——Ⅳ.苏(-)或(+)-1-(对硝基苯基)-1,3-二羟基丙胺-2为拆分剂

本文介绍以光学活性苏-1-(对硝基苯基)-1,3-二羟基丙胺-2为拆分剂,与消旋棉酚缩合,用常压柱色谱或溶剂结晶法分离得到两个光学纯的非对映体,然后分别水解得(+)和(-)-棉酚。     

Proton spectroscopic imaging (Dixon method) of the liver: clinical utility

The contribution of proton spectroscopic (PS) imaging to magnetic resonance (MR) imaging of the liver was assessed at 0.5 T in 55 patients with known or suspected hepatic malignancy. PS images were compared subjectively with T1- and T2-weighted spin-echo (SE) images for hepatic lesion detection and conspicuity. For hepatic metastases (n = 27), PS images were equal to T1-weighted images in lesion detection in 17 patients but showed fewer lesions in five patients and false-negative results in two. When compared with T2-weighted images, PS images depicted more lesions in six patients, an equal number of lesions in 18, and fewer lesions in two. Hepatomas (n = 8) were detected with each sequence in all patients. Hepatomas were often more conspicuous on PS images than on T2-weighted images; they were of equal conspicuity on PS and T1-weighted images in most cases. Whereas fatty infiltration (n = 16) appeared on PS images as areas of low signal intensity similar to that of paraspinal muscle, it produced no detectable abnormality on either T1- or T2-weighted images. PS imaging is inferior to T1-weighted SE imaging in the detection of hepatic metastases. The major role of PS imaging at intermediate field strength is to differentiate focal fatty infiltration from hepatic metastases.     

A new system for cutting brain tissue preserving vessels: water jet cutting

The water jet cutting system allows transaction and dissection of biological structures with little bleeding. Structures of higher tissue rigidity remain unchanged while softer tissues are mechanically dissected. In brain tissue, all vessels larger than 20 microns are left intact after the passage of the jet stream with a pressure of up to 5 bar, and therefore vessels can be isolated selectively from the surrounding tissue. Oedema is present adjacent to the cut and no increase of temperature occurs.     

Carbonic anhydrase histochemistry. A potential diagnostic method for peripheral nerve repair

Many large-diameter myelinated axons in spinal dorsal roots contain carbonic anhydrase activity, whereas few small-diameter ventral root axons stain for this enzyme. This differential localization of carbonic anhydrase in sensory and motor nerve fibers is indicative of the potential of carbonic anhydrase histochemistry to provide a convenient method for identifying predominantly motor or sensory fascicles in cut ends of peripheral nerves, thereby facilitating coaptation of fascicles in peripheral nerve repair.     

Sensory mapping.

The primary aim in reconstructive surgery of the upper extremity is to provide tactile gnosis to sensory depleted areas. It is essential for restoration of function and successful rehabilitation of the injured hand. Neurovascular free flaps may provide the answer to this catastrophic problem and transform a useless appendage into a functional gripping hand. Sensory mapping techniques can greatly assist the surgeon in precisely defining new donor sites for these transfers. Cutaneous sensibility, cutaneous sensation, and hand function are subjects of great complexity. Much more investigative and clinical work is needed in this challenging field to improve our evaluation of the sensory injury to the hand and to provide new avenues for restoring functional sensibility in the upper extremity.     

Intracerebral pneumatocele: CT findings

Two cases of intracerebral pneumatocele following trauma are presented. One to two months after initial treatment both patients had deteriorating neurologic status. The diagnosis was made by radiography. When a pneumatocele is suspected clinically, computed tomography can play a vital role in determining the precise location of the gas collection, its relationship to the fracture site, and the amount of mass effect on the brain.