The position of the lateral branch of the accessory nerve in relation to the internal jugular vein is given variously by different authors. In surgery of the neck, and especially in conservative cervical lymph node clearances, the lateral branch of the accessory nerve is protected when it is situated lateral to the vein. However, when the nerve is medial to the vein there is a risk of damage to the internal jugular vein. A prospective preoperative study of 123 cervical lymph node clearances, as well as a dissection study of 5 fresh subjects, was carried out to determine the position of the lateral branch of the accessory nerve in relation to the internal jugular vein. The surgical study showed that the lateral branch of the nerve was anterior and lateral to the vein in 122 of the 123 clearances, while the cadaveric study found the nerve always anterior and lateral to the vein. Thus the risk of injuring the internal jugular vein during cervical lymph node clearances is very small. The differences observed by authors may be explained by collapse of the internal jugular vein observed during cadaveric dissections.

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Two currently available methods of reducing motion-induced artifact on magnetic resonance (MR) images, respiratory-sorted phase encoding (RSPE) and gradient moment nulling (GMN), were compared in images of the upper abdomen obtained with long repetition and long echo times. For ten subjects, two series of axial MR images were obtained with identical parameters except that RSPE was used in one and GMN in the other. Images were evaluated by three independent radiologists, and region-of-interest measurements were obtained to calculate signal-difference-to-noise ratios (SD/Ns) for liver versus gallbladder and liver versus the right kidney. Maximum ghost intensity and the standard deviation of motion-induced noise were also calculated. GMN was superior to RSPE for motion artifact reduction in all ten cases. The SD/N for liver versus both gallbladder and right kidney was significantly higher with GMN. Presaturation pulses applied outside the volume of interest reduced aortic and inferior vena cava signal and virtually eliminated artifact from these vessels but did not noticeably affect signal from intrahepatic vessels. GMN combined with presaturation pulses is a highly effective method of motion artifact reduction in the upper abdomen.

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