Advanced Imaging of the Peripheral Nerves, From the AJR "How We Do It" Special Series.

Advanced imaging of peripheral nerves is occupying an increasingly important role in the diagnostic workup of peripheral nerve disorders. Advances in MR neurography (MRN) and high-resolution ultrasound have addressed historical challenges in peripheral nerve imaging related to nerves' small size and non-linear course, and difficult differentiation from surrounding tissues. Modern MRN depicts neuromuscular anatomy with exquisite contrast resolution, and MRN has become the workhorse imaging modality for peripheral nerve evaluation. MRN protocols vary across institutions and are adjusted in individual patients, although commonly include nerve-selective sequences and diffusion tensor imaging tractography. Ultrasound offers a dynamic, real-time high-resolution assessment of peripheral nerves, and is widely accessible and less costly than MRN. Ultrasound has greater ability to interrogate peripheral nerves at the fascicular level and provides complementary information to MRN. However, ultrasound of peripheral nerves requires substantial skill and experience and is operator-dependent. The two modalities have distinct advantages and disadvantages, and the selection between these depends on the clinical context. This article provides an overview of advanced imaging techniques used for evaluation of peripheral nerves, with attention to MRN and high-resolution ultrasound. We draw on our institutional experience in performing both modalities to highlight technical considerations for optimizing examinations.

Ultrasound-guided interventions of the upper extremity joints.

Ultrasound guidance is valuable for performing precise joint interventions. Joint interventions may be requested for therapeutic and diagnostic pain injections, joint aspiration in the setting of suspected infection, or contrast injection for arthrography. In practice, interventions of the shoulder girdle, elbow, and hand/wrist joints may be performed without any imaging guidance. However, imaging guidance results in more accurate interventions and better patient outcomes than those performed by palpation alone. When compared to other modalities used for imaging guidance, ultrasound has many potential advantages. Radiologists should be prepared to perform ultrasound-guided upper extremity joint interventions utilizing recommended techniques to optimize clinical practice and patient outcomes. KEY POINTS: 1. Ultrasound-guided injections of the glenohumeral, acromioclavicular, sternoclavicular, elbow, and hand/wrist joints have higher accuracy than injections performed without imaging guidance. 2. Ultrasound-guided aspirations of upper extremity joints have advantages to fluoroscopic-guided aspirations because of the potential to identify effusions, soft tissue abscess, or bursitis. 3. Ultrasound-guided contrast injection prior to MR arthrography is as accurate as fluoroscopic-guided injection for upper extremity joints.

Bleeding Associated With Feeding Tube Placement in Critically Ill Oncology Patients With Thrombocytopenia.

BACKGROUND: Existing trials have not evaluated the feasibility of oral or nasal feeding tube (FT) placement in the critically ill thrombocytopenic oncology population. Thrombocytopenia (TCP) may be considered a contraindication to FT placement due to the potential risk of bleeding complications. METHODS: Medical intensive care unit (ICU) adult oncology patients with attempted nasal or oral FT placement were evaluated in a 52-bed ICU at a comprehensive cancer center. End points were compared between patients with and without TCP (platelet count <150,000/µL). Primary outcomes of overt and clinically important bleeding (gastrointestinal and point of entry) were evaluated within 72 hours of FT placement. RESULTS: Fifty-nine patients were enrolled (TCP, n = 42; no TCP, n = 17; baseline platelet count, 41 ± 48 vs 249 ± 85 [× 10(3)/µL], P < .001). Patients with TCP were more likely to have a hematologic malignancy and lower baseline hemoglobin and platelet count (P < .01). More patients with TCP received blood products 24 hours prior to FT placement (86% vs 12%, P < .01). There was no difference in overt (7.1% vs 0%, P = .55) or clinically important (2.4% vs 5.9%, P = .5) bleeding complications within 72 hours of attempted FT placement among patients with TCP versus those without. CONCLUSIONS: Critically ill oncology patients with TCP do not appear to be at a higher risk for bleeding complications after FT placement compared with those without TCP, which may be related to blood product transfusion within 24 hours prior to FT placement.

Resolution of pneumobilia as a predictor of biliary stent occlusion.

OBJECTIVE: To predict biliary stent occlusion on computed tomography (CT) from the loss of pneumobilia. METHODS: A total of 66 patients with common bile duct stents with pneumobilia after initial stent placement had a follow-up CT and diagnostic endoscopic retrograde cholangiopancreatography (ERCP). Two readers evaluated all CT exams for pneumobilia. Resolution or decrease of pneumobilia on CT was compared with ERCP findings. RESULTS: Sensitivity and specificity was 60-64% and 95% with a positive predictive value of 97% and a negative predictive value of 49-51%. CONCLUSION: Resolution or reduction of pneumobilia after stent placement is specific (95%) and is moderately accurate (70-73%) for predicting biliary stent occlusion.

Pediatric chest CT after trauma: impact on surgical and clinical management.

BACKGROUND: Chest CT after pediatric trauma is frequently performed but its clinical impact, particularly with respect to surgical intervention, has not been adequately evaluated. OBJECTIVE: To assess the impact of chest CT compared with chest radiography on pediatric trauma management. MATERIALS AND METHODS: Two hundred thirty-five consecutive pediatric trauma patients who had both chest CT and radiography were identified. Images were reviewed and findings were categorized and correlated with subsequent chest interventions, blinded to final outcome and management. RESULTS: Of the 235 children, 38.3% (90/235) had an abnormal chest radiograph and 63.8% (150/235) had an abnormal chest CT (P < 0.0001). Chest interventions followed in 4.7% (11/235); of these, the findings could be made 1 cm above the dome of the liver in 91% (10/11). Findings requiring chest intervention included pneumothorax (PTX) and vertebral fractures. PTX was found on 2.1% (5/235) of chest radiographs and 20.0% (47/235) of chest CTs (P < 0.0001); 1.7% (4/235) of the children received a chest tube for PTX, 0.85% (2/235) seen on chest CT only. Vertebral fractures were present in 3.8% of the children (9/235) and 66.7% (6/9) of those cases were treated with spinal fusion or brace. There were no instances of mediastinal vascular injury. CONCLUSION: Most intrathoracic findings requiring surgical management in our population were identified in the lower chest and would be included in routine abdominopelvic CT exams; this information needs to be taken into consideration in the diagnostic algorithm of pediatric trauma patients.

Delirium and sedation in the intensive care unit: survey of behaviors and attitudes of 1384 healthcare professionals.

OBJECTIVE: A 2001 survey found that most healthcare professionals considered intensive care unit (ICU) delirium as a serious problem, but only 16% used a validated delirium screening tool. Our objective was to assess beliefs and practices regarding ICU delirium and sedation management. DESIGN AND SETTING: Between October 2006 and May 2007, a survey was distributed to ICU practitioners in 41 North American hospitals, seven international critical care meetings and courses, and the American Thoracic Society e-mail database. STUDY PARTICIPANTS: A convenience sample of 1384 healthcare professionals including 970 physicians, 322 nurses, 23 respiratory care practitioners, 26 pharmacists, 18 nurse practitioners and physicians' assistants, and 25 others. RESULTS: A majority [59% (766 of 1300)] estimated that more than one in four adult mechanically ventilated patients experience delirium. More than half [59% (774 of 1302)] screen for delirium, with 33% of those respondents (258 of 774) using a specific screening tool. A majority of respondents use a sedation protocol, but 29% (396 of 1355) still do not. A majority (76%, 990 of 1309) has a written policy on spontaneous awakening trials (SATs), but the minority of respondents (44%, 446 of 1019) practice spontaneous awakening trials on more than half of ICU days. CONCLUSIONS: Delirium is considered a serious problem by a majority of healthcare professionals, and the percent of practitioners using a specific screening tool has increased since the last published survey data. Although most respondents have adopted specific sedation protocols and have an approved approach to stopping sedation daily, few report even modest compliance with daily cessation of sedation.