Retropharyngeal Contralateral C7 Nerve Transfer to the Lower Trunk for Brachial Plexus Birth Injury: Technique and Results.

PURPOSE: Brachial plexus birth injuries with multiple nerve root avulsions present a particularly difficult reconstructive challenge because of the limited availability of donor nerves. The contralateral C7 has been described for brachial plexus reconstruction in adults but has not been well-studied in the pediatric population. We present our technique and results for retropharyngeal contralateral C7 nerve transfer to the lower trunk for brachial plexus birth injury. METHODS: We performed a retrospective review. Any child aged less than 2 years was included. Charts were analyzed for patient demographic data, operative variables, functional outcomes, complications, and length of follow-up. RESULTS: We had a total of 5 patients. Average nerve graft length was 3 cm. All patients had return of hand sensation to the ulnar nerve distribution as evidenced by a pinch test, unprompted use of the recipient limb without mirror movement, and an Active Movement Scale (AMS) of at least 2/7 for finger and thumb flexion; one patient had an AMS of 7/7 for finger and thumb flexion. Only one patient had return of ulnar intrinsic hand function with an AMS of 3/7. Two patients had temporary triceps weakness in the donor limb and one had clinically insignificant temporary phrenic nerve paresis. No complications were related to the retropharyngeal nerve dissection in any patient. Average follow-up was 3.3 years. CONCLUSIONS: The retropharyngeal contralateral C7 nerve transfer is a safe way to supply extra axons to the severely injured arm in brachial plexus birth injuries with no permanent donor limb deficits. Early functional recovery in these patients, with regard to hand function and sensation, is promising. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic V.

Reconstruction of the Isolated Columellar Defect: A Novel 2-Stage Technique and Review of the Literature.

The importance of the nasal complex cannot be overstated from a functional, social, and psychological perspective. The goal of reconstruction is to restore the trilaminar composition of the nose. This is accomplished by recreating the nasal lining and providing a cartilaginous framework to simultaneously support a patent airway and project the defining features to the overlying soft tissue. The columella is one of the smallest subunits of the nose, but the loss of this structure has important esthetic and structural implications. The ideal operation for an isolated defect of the columella remains elusive. The ideal reconstruction would match the pigmentation and texture of the surrounding nasal skin and provide a convex contour with underlying structural support. In addition, the donor site would not create a secondary deformity by disrupting normal anatomy. This report describes a novel 2-stage technique for reconstruction of the columella and reviews the current literature.

Management of the Acutely Burned Hand.

Despite contributing a small percentage to the total body surface area, hands are the most commonly burned body part and are involved in over 90% of severe burns. Although the mortality of isolated hand burns is negligible, morbidity can be substantial given our need for functioning hands when performing activities of daily living. The greatest challenges of treating hand burns are 2-fold. First, determining the depth of injury can be difficult even for the most experienced surgeon, but despite many diagnostic options, clinical examination remains the gold standard. Second, appropriate postoperative hand therapy is crucial and requires a multidisciplinary approach with an experienced burn surgeon, hand surgeon, and hand therapist. Ultimately, the goals of treatment should include preservation of function and aesthetics. In this review, we present an approach to the management of the acutely burned hand with discussion of both conservative and surgical options. Regardless of the initial treatment decision, subsequent care for this subset of patients should be aimed at preventing debilitating postburn scar contractures that can severely limit hand function and ultimately require reconstructive surgery.

Pediatric frontal sinus fractures: outcomes and treatment algorithm.

Pediatric frontal sinus fractures are a rare clinical entity. Owing to the large amount of force required to fracture the frontal sinus, it is often associated with severe intracranial and craniofacial injuries. The treatment of frontal sinus fractures is controversial, with many different established algorithms based mainly on the adult population. The authors present their experience with pediatric frontal sinus fractures; they also present a treatment algorithm. A retrospective review of the Cincinnati Children's Hospital Medical Center trauma database was performed. From 1998 to 2010, the authors identified patients between the ages of 0 and 18 with frontal sinus fractures and analyzed demographics, fracture pattern, associated injuries, methods of treatment, and complications. Descriptive statistics and univariate analyses were performed.A total of 39 patients were included in the study with a mean follow-up of 31.2 months. Fractures of the anterior and posterior table with displacement greater than one table width were significantly associated with higher hospital costs, higher velocity mechanism of injuries, lower Glasgow Coma Scale scores, nasofrontal outflow tract (NFOT) involvement, and cerebrospinal fluid leak. There were no differences in short- and long-term complications. Additionally, these patients were more likely to be treated surgically in the form of obliteration or cranialization.Patients without NFOT involvement can be managed with observation only. Patients with NFOT involvement or persistent cerebrospinal fluid leak should be treated with obliteration or cranialization, respectively, to reduce the risk of severe complications.

Thoracic outlet syndrome in the pediatric population: case series.

We present 4 patients, 4 months to 10 years of age, with thoracic outlet syndrome. All were referred to the brachial plexus clinic. Three patients were diagnosed with vascular thoracic outlet syndrome after clinical evaluation and diagnostic imaging. Three had a cervical rib and 1 had an anomalous first rib. All patients were treated surgically through a supraclavicular approach and had resolution of the symptoms. No postoperative complications were noted.

An optimized 3D spoiled gradient recalled echo pulse sequence for hemorrhage assessment using inversion recovery and multiple echoes (3D SHINE) for carotid plaque imaging.

Intraplaque hemorrhage into the carotid atherosclerotic plaque has been shown to create instability and progression. We have developed an optimized 3D Spoiled Gradient recalled echo pulse sequence for Hemorrhage assessment using INversion recovery and multiple Echoes (3D SHINE) for carotid plaque imaging. The sequence was developed by incorporating multiecho acquisition to its clinically validated optimized single-echo counterpart 3D inversion recovery prepared fast spoiled gradient recalled sequence. With similar scan time (4 min), 3D spoiled gradient recalled echo pulse sequence for hemorrhage assessment using inversion recovery and multiple echoes maintained comparable high-resolution volumetric coverage, black-blood effect, contrast, signal-to-noise and contrast-to-noise ratios, and similar sensitivity and specificity in detecting whether intraplaque hemorrhage was present on an artery. The multiple echoes acquired with 3D SHINE allowed the estimation of intraplaque hemorrhage T*(2) and then the subsequent characterization of intraplaque hemorrhage (T*(2) for type I < 14 msec, and for type II > 14 msec). The type I intraplaque hemorrhage size estimated by 3D SHINE was significantly and positively correlated with the size estimated manually by an expert reviewer using the histology-validated multicontrast MRI technique (r = 0.836 ± 0.080, p < 0.001). With only one fast sequence, 3D SHINE can detect and characterize intraplaque hemorrhage that has previously required a multicontrast approach using a combination of black-blood T(1)-weighted, black-blood T(2)-weighted, and time-of-flight imaging techniques.

Linear phase-error correction for improved water and fat separation in dual-echo dixon techniques.

Large and spatially-linear phase errors along the frequency-encode direction may be induced by several common and hard-to-avoid system imperfections such as eddy currents. For data acquired in dual-echo Dixon techniques, the linear phase error can be more aggravated when compared to that acquired in a single echo and can pose challenges to a phase-correction algorithm necessary for successful Dixon processing. In this work, we propose a two-step process that first corrects the linear component of the phase errors with a modified Ahn-Cho algorithm (Ahn CB and Cho ZH, IEEE Trans. Med. Imaging 6:32, 1987) and then corrects the residual phase errors with a previously-developed region-growing algorithm (Ma J, Magn. Res. Med. 52:415, 2004). We demonstrate that successive application of the two-step process to data from a dual-echo Dixon technique provides a "1-2 punch" to the overall phase errors and can overcome local water and fat separation failures that are observed when the region-growing-based algorithm is applied alone.

Structural characterization of the α-mating factor prepro-peptide for secretion of recombinant proteins in Pichia pastoris.

The methylotrophic yeast Pichia pastoris has been used extensively for expressing recombinant proteins because it combines the ease of genetic manipulation, the ability to provide complex posttranslational modifications and the capacity for efficient protein secretion. The most successful and commonly used secretion signal leader in Pichia pastoris has been the alpha mating factor (MATα) prepro secretion signal. However, limitations exist as some proteins cannot be secreted efficiently, leading to strategies to enhance secretion efficiency by modifying the secretion signal leader. Based on a Jpred secondary structure prediction and knob-socket modeling of tertiary structure, numerous deletions and duplications of the MATα prepro leader were engineered to evaluate the correlation between predicted secondary structure and the secretion level of the reporters horseradish peroxidase (HRP) and Candida antarctica lipase B. In addition, circular dichroism analyses were completed for the wild type and several mutant pro-peptides to evaluate actual differences in secondary structure. The results lead to a new model of MATα pro-peptide signal leader, which suggests that the N and C-termini of MATα pro-peptide need to be presented in a specific orientation for proper interaction with the cellular secretion machinery and for efficient protein secretion.

Repair of a Critical Porcine Tibial Defect by Means of Allograft Revitalization.

BACKGROUND: The authors previously described the generation of vascularized bone in a pig model, using a hemimandibular allograft scaffold, adipose-derived stem cells, recombinant human bone morphogenetic protein-2, and periosteum. This study tests the hypothesis that this "allograft revitalization" technique is as effective as vascularized autograft for repairing critical bony defects. METHODS: Three groups of pigs had 3-cm defects created in their bilateral tibial diaphyses for repair using rigid fixation and one of three modalities. Negative control tibias were repaired with allograft tibia alone. To simulate repair using vascularized autograft, the osteotomized bone in positive control animals was left in situ, with the posterior periosteum intact. Experimental animals' defects were repaired with allograft tibia packed with autologous adipose-derived stem cells and recombinant human bone morphogenetic protein-2, with native periosteum intact. After 8 weeks, unilateral midgraft osteotomies were performed to assess graft healing potential. Serial radiographs and terminal micro-computed tomography and histology enabled evaluation of healing. RESULTS: At week 7 after ostectomy, no negative control tibias had healed (zero of six) whereas most positive control (five of six) and all experimental tibias (six of six) had healed. Unilateral midgraft osteotomies were performed at 8 weeks to assess graft ability to heal. As expected, no negative control tibias (three of three) had radiographic union 7 weeks later. However, all positive control (two of two; p = 0.05) and experimental (three of three; p = 0.01) tibias had healed their repeated osteotomies by this time. CONCLUSION: Similar to vascularized autograft, revitalized allograft successfully repaired a critical tibial defect, including after refracture, suggesting that this technique may be an alternative to osseous free flaps.

Three-dimensional fast spoiled gradient-echo dual echo (3D-FSPGR-DE) with water reconstruction: preliminary experience with a novel pulse sequence for gadolinium-enhanced abdominal MR imaging.

PURPOSE: To compare three-dimensional fast spoiled gradient-echo dual-echo (3D-FSPGR-DE) with water reconstruction to conventional 3D-FSPGR for gadolinium-enhanced abdominal imaging. MATERIALS AND METHODS: Sixty-five patients underwent abdominal MRI on a 1.5T GE-HDx MR scanner using gadolinium-enhanced 3D-FSPGR and 3D-FSPGR-DE imaging. Qualitatively, FSPGR-DE and 3D-FSPGR images were reviewed side by side for normal anatomic structures, artifacts, and image quality. The images were reviewed separately for abnormalities of abdominal organs. Receiver operating characteristic (ROC) curve analysis was performed. Quantitative analysis measured mean signal intensity of liver, spleen, aorta, liver lesions, and noise. RESULTS: Observers preferred FSPGR-DE for evaluating liver, vessels, muscles, and subcutaneous tissues. Fat suppression was superior on FSPGR-DE in 63 (0.97) and 61 (0.94) of 65 cases for two observers. FSPGR-DE showed less susceptibility artifact in 47 (0.72) and 41 (0.63) cases, better signal in edge slices in 60 (0.92) and 60 (0.92) cases, less phase artifact in 42 (0.65) and 45 (0.69) cases, and less parallel imaging artifact in 13 (0.20) and 10 (0.15) cases. Images were equivalent for depicting abdominal findings with no difference in the area under the ROC curve. FSPGR-DE images showed a 20%, 29%, and 34% increase in liver, splenic, and aortic signal, respectively, and a 45% and 62% increase in liver-lesion contrast and contrast-to-noise ratio (CNR), respectively. CONCLUSION: Gadolinium-enhanced 3D-FSPGR-DE with water reconstruction provides volumetric abdominal imaging with superior image quality, more homogeneous fat suppression, reduced artifacts, and improved image signal and homogeneity.

Multiecho reconstruction for simultaneous water-fat decomposition and T2* estimation.

PURPOSE: To describe and demonstrate the feasibility of a novel multiecho reconstruction technique that achieves simultaneous water-fat decomposition and T2* estimation. The method removes interference of water-fat separation with iron-induced T2* effects and therefore has potential for the simultaneous characterization of hepatic steatosis (fatty infiltration) and iron overload. MATERIALS AND METHODS: The algorithm called "T2*-IDEAL" is based on the IDEAL water-fat decomposition method. A novel "complex field map" construct is used to estimate both R2* (1/T2*) and local B(0) field inhomogeneities using an iterative least-squares estimation method. Water and fat are then decomposed from source images that are corrected for both T2* and B(0) field inhomogeneity. RESULTS: It was found that a six-echo multiecho acquisition using the shortest possible echo times achieves an excellent balance of short scan and reliable R2* measurement. Phantom experiments demonstrate the feasibility with high accuracy in R2* measurement. Promising preliminary in vivo results are also shown. CONCLUSION: The T2*-IDEAL technique has potential applications in imaging of diffuse liver disease for evaluation of both hepatic steatosis and iron overload in a single breath-hold.

Fat-suppressed three-dimensional dual echo Dixon technique for contrast agent enhanced MRI.

PURPOSE: To develop a fast T1-weighted, fat-suppressed three-dimensional dual echo Dixon technique and to demonstrate its use in contrast agent enhanced MRI. MATERIALS AND METHODS: A product fast three-dimensional gradient echo pulse sequence was modified to acquire dual echoes after each RF excitation with water and fat signals in-phase (IP) and opposed-phase (OP), respectively. An on-line reconstruction algorithm was implemented to automatically generate separate water and fat images. The signal to noise ratio (SNR) of the new technique was compared to that of the product technique in phantom. In vivo abdomen and breast images of cancer patients were acquired at 1.5 Tesla using both techniques before and after intravenous administration of gadolinium contrast agent. RESULTS: In phantom, the new technique yields a close to the theoretically predicted 41% increase in SNR in comparison to the product technique without fat suppression (FS). In vivo images of the new technique show noticeably improved FS and image quality in comparison to the images acquired of the same patients using the product technique with FS. CONCLUSION: The three-dimensional dual echo Dixon technique provides excellent image quality and can be used for T1-weighted, fat-suppressed imaging with contrast agent injection.

Scoutless stepping-table peripheral contrast-enhanced MR angiography.

PURPOSE: To evaluate the feasibility of a scoutless method, termed EZ-STEP, for stepping-table peripheral contrast-enhanced magnetic resonance angiography (CE-MRA). MATERIALS AND METHODS: This scoutless method involves the use of a stepping-table, fast 3D MRA acquisition that incorporates spatially nonselective radiofrequency (RF) pulses for excitation to reduce the repetition time (TR). The sequence was tested in a phantom. The EZ-STEP protocol was optimized in four healthy volunteers and used in 15 subjects. The image quality was scored in a blinded fashion and compared with conventional MRA in eight patients. RESULTS: The acquisition speed of the EZ-STEP sequence was approximately 30% faster in the phantom study compared to the conventional MRA sequence. The total examination time for EZ-STEP was 6 minutes, compared to an average of 23 minutes for conventional MRA. The average image quality scores for EZ-STEP and conventional MRA for stations 1-3 were 3.50 vs. 3.06 (P = 0.087), 3.53 vs. 3.00 (P = 0.033), and 2.97 vs. 2.50 (P = 0.090), respectively. CONCLUSION: EZ-STEP is a more efficient method than the conventional approach for stepping-table peripheral CE-MRA, and provides comparable or better image quality. This method shortens the examination time substantially and eliminates the risk of failing to image a vessel because of improper positioning of the scan volume.

First-pass contrast-enhanced magnetic resonance angiography in humans using ferumoxytol, a novel ultrasmall superparamagnetic iron oxide (USPIO)-based blood pool agent.

PURPOSE: To evaluate the feasibility of first-pass contrast-enhanced magnetic resonance angiography (MRA) using ferumoxytol in humans. MATERIALS AND METHODS: First-pass and equilibrium phase MRA were performed using ferumoxytol in one healthy volunteer and 11 patients with a fast three-dimensional spoiled gradient recalled (SPGR) pulse sequence. The examined vessels included carotid arteries, thoracic aorta, abdominal aorta, and peripheral arteries. A dose of either 71.6 micromol Fe/kg (n = 9), or 35.8 micromol Fe/kg (n = 3) was used. Based on a phantom study, the agent with initial concentration of 537.2 micromol Fe/mL was diluted by either four-fold (134.3 micromol Fe/mL) or eight-fold (67.1 micromol Fe/mL) for first-pass MRA. RESULTS: All subjects completed their studies without adverse events. First-pass MRA showed selective arterial enhancement, with both arterial and venous enhancement on delayed acquisitions. Selective venous enhancement could be obtained by subtraction of arterial phase images from equilibrium phase images. The findings in ferumoxytol MRA were consistent with the results of original vascular tests. CONCLUSION: Our preliminary experience supports the feasibility of first-pass MRA with ferumoxytol. Satisfactory arterial enhancement during first-pass imaging is obtained with injection of diluted contrast agent. With ferumoxytol, arteries and veins can be selectively depicted in a single exam.

Evaluation of intrarenal oxygenation by BOLD MRI at 3.0 T.

PURPOSE: To examine the benefit of using higher field strengths for BOLD MRI to detect changes in renal medullary oxygenation following pharmacological maneuvers. MATERIALS AND METHODS: Renal BOLD MRI, primarily at 1.5 T, has been shown to be useful for monitoring changes in medullary oxygenation status. We performed the present studies on a 3.0 T scanner using a multiple gradient-echo (mGRE) sequence with a multicoil array to acquire 16 T2*-weighted images within a single breath-hold. Data were obtained before and after administration of furosemide (20 mg iv). RESULTS: The baseline renal R2* (mean +/- SE) at 3.0 T was 37.4+/-1.2 Hz in the medulla, and 21.8 +/- 1.2 Hz in the cortex. The BOLD response to furosemide (DeltaR2*) at 3.0 T was 11.8 +/- 1.1 Hz in the medulla, and 3.0 +/- 0.5 Hz in the cortex. CONCLUSION: Higher magnetic field strength is beneficial for renal BOLD MRI studies. The cortico-medullary contrast on the R2* map was significantly improved at 3.0 T, with no evidence of increased bulk susceptibility artifacts. Baseline R2* and DeltaR2* in the renal medulla at 3.0 T were both significantly higher compared to our previously reported data obtained at 1.5 T.