Infections in British clinical laboratories, 1988-1989.

During 1988-89 this continuing survey showed 18 infections in the staff of laboratories reporting from 166 centres, representing 21,756 person-years of exposure. Shigella and other bowel infections (one caused by S typhi) predominated, affecting 11 microbiology medical laboratory scientific officers. Three shigella infections originated from quality control samples. Pulmonary tuberculosis affected four workers, including two mortuary technicians, but without detected occupational exposure to Mycobacterium tuberculosis. Other infections included one caused by Brucella melitensis. Hepatitis was not reported. The sustained low level of hepatitis is encouraging and suggests a low risk to staff of bloodborne infections such as human immunodeficiency virus.     

Carotid body tumor: flow sensitive pulse sequences and MR angiography

The magnetic resonance (MR) appearance of carotid body tumors has been previously described. Classically, these lesions are well circumscribed and highly vascular and cause a characteristic separation of the external and internal carotid arteries. Hypointense foci within these tumors are seen on T1-weighted images. The T2-weighted images snow a "salt and pepper" pattern. We report a carotid bifurcation glomus tumor that exhibited the above features on conventional MR. Multiplanar gadolinium enhanced MR as well as flow-sensitive MR techniques including small flip angle gradient refocused images and MR angiography were performed. Magnetic resonance angiography demonstrated the abnormal morphology of the carotid bifurcation. Axial gradient refocused images revealed evidence of flow within the lesion. The findings were then correlated with postcontrast CT, arterial digital subtraction angiography, and histopathology.     

The sectorial loop-gap resonator for 31P NMR of the adult human liver at 1.5 T with surface tissue suppression

A new type of loop-gap resonator, which because of its topology is called a "sectorial resonator," is described in considerable analytical detail. It was used for 31P NMR of the livers of two human adult normal volunteers. An effective strategy for suppression of signals from surface tissue was developed. Depth selection was achieved using a separate excitation coil, permitting a reasonable degree of control of the shape of the sensitive region by adjustment of the dimensions of the excitation coil and of the type of pulse delivered. In addition a new principle for cancellation is described: the topology of the sectorial resonator leads to cancellation signals from tissue masses at the two openings of the structure. Using a phase-alternated repeated 90 degrees FID pulse sequence, good spectra were achieved in 2.5 min that are free from contamination by the phosphocreatine peak.     

3D MR DSA: effects of injection protocol and image masking

The purpose of this study was to investigate the effect on three-dimensional (3D) magnetic resonance digital subtraction angiography (MR DSA) images of various injection protocol parameters (ie, injection order, volume, and rate), as well as image masking. The pelves of 10 normal volunteers were scanned using seven different contrast agent volume/injection rate combinations. Subtraction of a precontrast mask image resulted in vascular image contrast improvements of between 4.0 and 7.7 times. Image quality and smaller vessel image contrast in the masked data decreased with increasing injection number. Data acquired with a high (0.150 mmol kg(-1)) volume yielded the highest quality images, although only small nonsignificant differences in image quality and large vessel conspicuity were found between images obtained using the high and medium (0.075 mmol kg(-1)) volumes. Images acquired with a low (0. 038 mmol kg(-1)) volume, while of lower image contrast, were judged to be of reasonable quality, especially when acquired as the first or second injection. Injection rate (1 ml s(-1), 2 ml s(-1), and 4 ml s(-1)) was not found to affect the images significantly, although selection of an injection rate that gave an injection duration of approximately 10 seconds tended to give better vascular image contrast. Based on these data, a series of escalating volumes for multi-injection examination is proposed. J. Magn. Reson. Imaging 2000;12:476-487.