Detection rate and efficiency of lymph node assessment with axial and coronal image reading based on 16 row multislice CT of the neck.

PURPOSE: Multislice CT (MSCT) has the advantage of isotropic volumetric data acquisition which allows high resolution data reconstruction in the axial and coronal plane. We evaluate the accuracy and efficiency of coronal reconstruction compared to axial reconstructions of a routinely performed CT scan exemplary in neck lymph node assessment performed on a 16 row MSCT. MATERIAL AND METHODS: Contrast enhanced neck MSCT of 24 patients with known lymphoma were evaluated prospectively for lymph node assessment. 4 blinded readers evaluated the axial and coronal reconstructions of the same patient. Neck lymph nodes larger than 10 mm were evaluated by their anatomical region (deep jugular chain, submandibular, nuchal). Time for axial and coronal image evaluation was assessed. Detection rate was compared with consensus reading as gold standard. RESULTS: In consensus reading 169 enlarged lymph nodes in the deep jugular chain were found. Detection rate for axial image interpretation was 36.1 % with 54.9 % in coronal reading. Assessing the submandibular lymph nodes (n = 45) axial interpretation revealed 53.9 % with 36.1 % in coronal reading. Evaluation time for axial reading was in all but one reader significantly longer (mean 176 seconds) than in coronal reading (mean 129 seconds). CONCLUSION: Coronal image reading improves the detection rate of cranio-caudal oriented structures. Considering representatively neck lymph nodes in the deep jugular chain the image interpretation time is significantly reduced. Still axial reading remains necessary for assessing axially oriented structures such as the submandibular region in the neck.

Ultrasonographic assessment of topographic anatomy in volunteers suggests a modification of the infraclavicular vertical brachial plexus block.

BACKGROUND: The infraclavicular vertical brachial plexus block, first described by Kilka and coworkers, offers a more proximal spread of anaesthesia for the upper extremity than the classic axillary approach. In this technique, the puncture site is defined as lying at the exact centre of an infraclavicular line (k) between the jugular fossa and the ventral process of the acromion. Our study was designed to determine whether the point so defined (P) corresponds with the optimal puncture site determined sonographically (S) and to develop an improved prediction model. METHOD: High-resolution ultrasonography was carried out in 59 volunteers to visualize the plexus. Sonography-derived distances and morphometric measurements were used to test accuracy and calculate multiple regressions. RESULTS: We found a clear trend towards a more lateral puncture site. In women, S was significantly (P<0.001) lateral (8 mm) to P. The overall accuracy of the infraclavicular vertical brachial plexus block technique was not sufficient to predict the optimal puncture site reliably. Our resulting improved prediction model is valid for both sexes and is based not just on the centre point but on the absolute length of k (22-22.5 cm). We found that for every 1 cm decrease in k the optimal puncture site moved 2 mm laterally from the exact centre of k, and for every 1 cm increase in k it moved 2 mm medially. CONCLUSIONS: The suggested modification should help to increase the success rate of the infraclavicular vertical brachial plexus block while decreasing the rate of potentially severe complications, although individual ultrasonographic guidance is to be recommended whenever possible.

Ultrasonographic findings of the axillary part of the brachial plexus.

UNLABELLED: In this prospective study we sought to determine anatomic variations of the main brachial plexus nerves in the axilla and upper arm via high-resolution ultrasonography (US) examination. Positions of nerves were studied via US in three sectional levels of the upper arm in 69 healthy volunteers (31 men and 38 women, median age 28 yr). Analysis was done by subdividing the US picture into eight pie-chart sectors and matching sectors for the position of the ulnar, radial, and median nerves. Shortly after the nerves pass the pectoralis minor muscle, they begin to diverge. At the middle level 9%-13%, and at the distal level, 30%-81% of the nerves are not seen together with the artery in the US picture. At the usual level of axillary block approach, we found the ulnar nerve in the posterior medial position in 59% of the volunteers. The other two nerves had two peaks in distribution: the radial nerve in posterior lateral (38%) and anterior lateral (20%) position, and the median nerve in anterior medial (30%) and posterior medial (26%) position. Applying light pressure distally can displace nerves to the side, especially when they are positioned anterior to the axillary artery. We conclude that an axillary block should be attempted as proximal as possible to the axilla. IMPLICATIONS: This prospective ultrasonography study demonstrates significant anatomic variations of the main brachial plexus nerves in the axilla and upper arm, which may increase the difficulty in identifying neural structures. Applying light pressure on the plexus can move nerves to the side, especially when they are positioned anterior to the axillary artery.