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MR Imaging the spinal cord of non-human primates (NHP), such as squirrel monkey, is important since the injuries in NHP resemble those that afflict human spinal cords. Our previous studies have reported a multi-parametric MRI protocol, including functional MRI, diffusion tensor imaging, quantitative magnetization transfer and chemical exchange saturation transfer, which allows non-invasive detection and monitoring of injury-associated structural, functional and molecular changes over time. High signal-to-noise ratio (SNR) is critical for obtaining high-resolution images and robust estimates of MRI parameters. In this work, we describe our construction and use of a single channel coil designed to maximize the SNR for imaging the squirrel monkey cervical spinal cord in a 21 cm bore magnet at 9.4 T. We first numerically optimized the coil dimension of a single loop coil and then evaluated the benefits of a quadrature design. We then built an optimized coil based on the simulation results and compared its SNR performance with a non-optimized single coil in both phantoms and in vivo.
Copyright © 2020 Elsevier Inc. All rights reserved.
PURPOSE - To measure the transverse relaxation time T* in healthy human cervical spinal cord gray matter (GM) and white matter (WM) at 3T.
METHODS - Thirty healthy volunteers were recruited. Axial images were acquired using an averaged multi-echo gradient-echo (mFFE) T*-weighted sequence with 5 echoes. We used the signal equation for an mFFE sequence with constant dephasing gradients after each echo to jointly estimate the spin density and T* for each voxel.
RESULTS - No global difference in T* was observed between all GM (41.3 ± 5.6 ms) and all WM (39.8 ± 5.4 ms). No significant differences were observed between left (43.2 ± 6.8 ms) and right (43.4 ± 5.5 ms) ventral GM, left (38.3 ± 6.1 ms) and right (38.6 ± 6.5 ms) dorsal GM, and left (39.4 ± 5.8 ms) and right (40.3 ± 5.8 ms) lateral WM. However, significant regional differences were observed between ventral (43.4 ± 5.7 ms) and dorsal (38.4 ± 6.0 ms) GM (p < 0.05), as well as between ventral (42.9 ± 6.5 ms) and dorsal (37.9 ± 6.2 ms) WM (p < 0.05). In analyses across slices, inferior T* was longer than superior T* in GM (44.7 ms vs. 40.1 ms; p < 0.01) and in WM (41.8 ms vs. 35.9 ms; p < 0.01).
CONCLUSIONS - Significant differences in T* are observed between ventral and dorsal GM, ventral and dorsal WM, and superior and inferior GM and WM. There is no evidence for bilateral asymmetry in T* in the healthy cord. These values of T* in the spinal cord are notably lower than most reported values of T* in the cortex.
© 2019 International Society for Magnetic Resonance in Medicine.
OBJECTIVE - To determine if there is a critical depth of invasion that predicts micrometastasis in early oral tongue cancer.
METHODS - Retrospective series identifying patients undergoing primary surgical resection of T1 or T2 oral tongue cancer who elected against neck treatment between 2000 and 2015. Cox proportional-hazard model compared the relative hazard and cumulative incidence of recurrence to depth of invasion. The model used a 2 parameter quadratic effect for depth that was chosen based on Akaike's information criterion.
RESULTS - Ninety-three patients were identified with T1 or T2 oral tongue squamous cell carcinoma and clinically N0 neck undergoing glossectomy without elective neck treatment. 61% were male and median age was 60 years. Median follow up was 45 months, and 76 patients had at least two years of follow up. Thirty-six of 76 patients recurred (47.4%), with 15 recurring in the oral cavity (19.7%) and 21 developing nodal metastasis (27.6%). Cox proportional-hazards quadratic polynomial showed increasing hazard of recurrence with depth of invasion and the cumulative incidence increased sharply within the range of data from 2 to 6 mm depth of invasion.
CONCLUSIONS - Depth of invasion is significantly associated with nodal metastasis and has been added to the 8th AJCC staging guidelines. Variable depths of invasion have been associated with regional metastasis; however, there is likely not a critical depth that predicts neck recurrence due to progressive hazards and cumulative risk of occult metastasis. The risk of regional metastasis is likely much greater than previously believed and increases progressively with increasing depth.
Copyright © 2018 Elsevier Ltd. All rights reserved.
This study aimed to determine the association between areal and volumetric bone mineral density (BMD) with all-cause mortality in patients with type 2 diabetes (T2D). Associations between BMD and all-cause mortality were examined in 576 women and 517 men with T2D in the Diabetes Heart Study. Volumetric BMD in the thoracic and lumbar spine was measured with quantitative computed tomography. Areal BMD (aBMD) in the lumbar spine, total hip, femoral neck, ultradistal radius, mid radius, and whole body was measured using dual X-ray absorptiometry. Association of BMD with all-cause mortality was determined using sequential models, stratified by sex: (1) unadjusted; (2) adjusted for age, race, smoking, alcohol, estrogen use; (3) model 2 plus history of cardiovascular disease, hypertension, and coronary artery calcification; (4) model 3 plus lean mass; and (5) model 3 plus fat mass. At baseline, mean age was 61.2 years for women and 62.7 years for men. At mean 11.0 ± 3.7 years' follow-up, 221 (36.4%) women and 238 (43.6%) men were deceased. In women, BMD at all skeletal sites (except spine aBMD and whole body aBMD) was inversely associated with all-cause mortality in the unadjusted model. These associations remained significant in the mid radius (hazard ratio per standard deviation = 0.79; p = 0.0057) and distal radius (hazard ratio per standard deviation = 0.76; p = 0.0056) after adjusting for all covariates, including lean mass. In men, volumetric BMD measurements but not aBMD were inversely associated with mortality and only in the unadjusted model. In this longitudinal study, lower baseline aBMD in the radius was associated with increased all-cause mortality in women with T2D, but not men, independent of other risk factors for death.
Copyright © 2017 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.
PURPOSE - Automated delineation of structures and organs is a key step in medical imaging. However, due to the large number and diversity of structures and the large variety of segmentation algorithms, a consensus is lacking as to which automated segmentation method works best for certain applications. Segmentation challenges are a good approach for unbiased evaluation and comparison of segmentation algorithms.
METHODS - In this work, we describe and present the results of the Head and Neck Auto-Segmentation Challenge 2015, a satellite event at the Medical Image Computing and Computer Assisted Interventions (MICCAI) 2015 conference. Six teams participated in a challenge to segment nine structures in the head and neck region of CT images: brainstem, mandible, chiasm, bilateral optic nerves, bilateral parotid glands, and bilateral submandibular glands.
RESULTS - This paper presents the quantitative results of this challenge using multiple established error metrics and a well-defined ranking system. The strengths and weaknesses of the different auto-segmentation approaches are analyzed and discussed.
CONCLUSIONS - The Head and Neck Auto-Segmentation Challenge 2015 was a good opportunity to assess the current state-of-the-art in segmentation of organs at risk for radiotherapy treatment. Participating teams had the possibility to compare their approaches to other methods under unbiased and standardized circumstances. The results demonstrate a clear tendency toward more general purpose and fewer structure-specific segmentation algorithms.
© 2017 American Association of Physicists in Medicine.
BACKGROUND - Planning and delivery of IMRT for locally advanced head and neck cancer (LAHNC) can be performed using sequential boost or simultaneous integrated boost (SIB). Whether these techniques differ in treatment-related outcomes including survival and acute and late toxicities remain largely unexplored.
METHODS - We performed a single institutional retrospective matched cohort analysis on patients with LAHNC treated with definitive chemoradiotherapy to 69.3 Gy in 33 fractions. Treatment was delivered via sequential boost (n = 68) or SIB (n = 141). Contours, plan evaluation, and toxicity assessment were performed by a single experienced physician. Toxicities were graded weekly during treatment and at 3-month follow up intervals. Recurrence-free survival, disease-free survival, and overall survival were estimated via Kaplan-Meier statistical method.
RESULTS - At 4 years, the estimated overall survival was 69.3% in the sequential boost cohort and 76.8% in the SIB cohort (p = 0.13). Disease-free survival was 63 and 69% respectively (p = 0.27). There were no significant differences in local, regional or distant recurrence-free survival. There were no significant differences in weight loss (p = 0.291), gastrostomy tube placement (p = 0.494), or duration of gastrostomy tube dependence (p = 0.465). Rates of acute grade 3 or 4 dysphagia (82% vs 55%) and dermatitis (78% vs 58%) were significantly higher in the SIB group (p < 0.001 and p = 0.012 respectively). Moreover, a greater percentage of the SIB cohort did not receive the prescribed dose due to acute toxicity (7% versus 0, p = 0.028).
CONCLUSIONS - There were no differences in disease related outcomes between the two treatment delivery approaches. A higher rate of grade 3 and 4 radiation dermatitis and dysphagia were observed in the SIB group, however this did not translate into differences in late toxicity. Additional investigation is necessary to further evaluate the acute toxicity differences.
Laminin peptides influence tumor behavior. In this study, we addressed whether laminin peptide C16 (KAFDITYVRLKF, γ1 chain) would increase invadopodia activity of cells from squamous cell carcinoma (CAL27) and fibrosarcoma (HT1080). We found that C16 stimulates invadopodia activity over time in both cell lines. Rhodamine-conjugated C16 decorates the edge of cells, suggesting a possible binding to membrane receptors. Flow cytometry showed that C16 increases activated β1 integrin, and β1 integrin miRNA-mediated depletion diminishes C16-induced invadopodia activity in both cell lines. C16 stimulates Src and ERK 1/2 phosphorylation, and ERK 1/2 inhibition decreases peptide-induced invadopodia activity. C16 also increases cortactin phosphorylation in both cells lines. Based on our findings, we propose that C16 regulates invadopodia activity over time of squamous carcinoma and fibrosarcoma cells, probably through β1 integrin, Src and ERK 1/2 signaling pathways.
INTRODUCTION - Impaired bladder emptying in women without neurologic disease may be related to urethral obstruction and/or impaired bladder contractility. Mechanical obstruction generally requires surgical management and options are limited for impaired bladder contractility. However, functional obstruction from voiding dysfunction or primary bladder neck obstruction may present an opportunity for pharmacologic intervention.
AREAS COVERED - In this review, the authors extensively reviewed available literature regarding the use of off-label medications for functional bladder outlet obstruction in women. In addition, side effect profiles and pharmacology of these medications determined from on-label indications are reviewed. Specific medications reviewed include vaginal diazepam, baclofen, urethral botulinum toxin injection, and alpha-adrenergic blockers.
EXPERT OPINION - Alpha-blockers in particular have demonstrated promise in women with demonstrable or suspected bladder outlet obstruction with side effect profiles similar to those observed in men. However, lack of quality data hinders informed decision making with alpha-blockers or any of the other agents studied in women with non-neurogenic functional outlet obstruction. In the absence of well-designed, placebo-controlled multi-institutional trials, those prescribing these medications must be aware of special considerations and side effects associated with relatively unfamiliar treatments in the context of uncertain benefit.