Imaging assessment of spine infection.

This article comprehensively reviews current imaging concepts in spinal infection with primary focus on infectious spondylodiscitis (IS) as well as the less common entity of facet joint septic arthritis (FSA). This review encompasses the multimodality imaging appearances (radiographs, CT, MRI, and nuclear imaging) of spinal infection-both at initial presentation and during treatment-to aid the radiologist in guiding diagnosis and successful management. We discuss the pathophysiology of spinal infection in various patient populations (including the non-instrumented and postoperative spine) as well as the role of imaging-guided biopsy. We also highlight several non-infectious entities that can mimic IS (both clinically and radiologically) that should be considered during image interpretation to avoid misdiagnosis. These potential mimics include the following: Modic type 1 degenerative changes, acute Schmorl's node, neuropathic spondyloarthropathy, radiation osteitis, and inflammatory spondyloarthropathy (SAPHO syndrome).

Imaging of Nerve Disorders in the Elbow.

Neuropathies of the elbow represent a spectrum of disorders that involve more frequently the ulnar, radial, and median nerves. Reported multiple pathogenic factors include mechanical compression, trauma, inflammatory conditions, infections, as well as tumor-like and neoplastic processes. A thorough understanding of the anatomy of these peripheral nerves is crucial because clinical symptoms and imaging findings depend on which components of the affected nerve are involved. Correlating clinical history with the imaging manifestations of these disorders requires familiarity across all diagnostic modalities. This understanding allows for a targeted imaging work-up that can lead to a prompt and accurate diagnosis.

Semi-Automated 3D Volumetric Renal Measurements in Polycystic Kidney Disease Using b0-Images-A Feasibility Study.

Autosomal dominant polycystic kidney disease (ADPKD) eventually leads to end stage renal disease (ESRD) with an increase in size and number of cysts over time. Progression to ESRD has previously been shown to correlate with total kidney volume (TKV). An accurate and relatively simple method to perform measurement of TKV has been difficult to develop. We propose a semi-automated approach of calculating TKV inclusive of all cysts in ADPKD patients based on b0 images relatively quickly without requiring any calculations or additional MRI time. Our purpose is to evaluate the reliability and reproducibility of our method by raters of various training levels within the environment of an advanced 3D viewer. Thirty patients were retrospectively identified who had DWI performed as part of 1.5T MRI renal examination. Right and left TKVs were calculated by five radiologists of various training levels. Interrater reliability (IRR) was estimated by computing the intraclass correlation (ICC) for all raters. ICC values calculated for TKV measurements between the five raters were 0.989 (95% CI = (0.981, 0.994), p < 0.01) for the right and 0.961 (95% CI = (0.936, 0.979), p < 0.01) for the left. Our method shows excellent intraclass correlation between raters, allowing for excellent interrater reliability.

Dynamic Stress MRI of Midfoot Injuries: Measurable Morphology and Laxity of the Sprained Lisfranc Ligament During Mechanical Loading: A Case Report.

CASE: Our 26-year-old patient is a professional ballet dancer who suffered a classic Lisfranc joint injury while performing a dancing maneuver with his foot in full plantar flexion. Initial workup with radiographs revealed borderline Lisfranc interval widening without definitive joint instability. Further evaluation with an innovative dynamic stress magnetic resonance imaging (MRI) revealed mild interosseous Lisfranc ligament laxity and sprain, which allowed the orthopaedic surgeon to pursue conservative management, rather than surgery. After physical therapy, our patient reports a successful return to dancing. CONCLUSIONS: Dynamic stress MRI may become a useful technique in evaluating equivocal cases of midfoot injury through the use of new imaging-based criteria.

Quantitative magnetic resonance imaging analysis of the cross-sectional areas of the anconeus epitrochlearis muscle, cubital tunnel, and ulnar nerve with the elbow in extension in patients with and without ulnar neuropathy.

BACKGROUND: The purpose of this study was to assess the cross-sectional area of the anconeus epitrochlearis muscle (AEM), cubital tunnel, and ulnar nerve with the elbow in extension in patients with and without ulnar neuropathy. METHODS: We performed a retrospective, level IV review of elbow magnetic resonance imaging (MRI) studies. Elbow MRI studies of 32 patients with an AEM (26 men and 6 women, aged 18-60 years), 32 randomly selected patients without an AEM (aged 16-71 years), and 32 patients with clinical ulnar neuritis (22 men and 10 women, aged 24-76 years) were reviewed. We evaluated the ulnar nerve cross-sectional area proximal to, within, and distal to the cubital tunnel; AEM cross-sectional area; and cubital tunnel cross-sectional area. RESULTS: We found no significant difference in the nerve caliber between patients with and without an AEM. No correlation was found between the AEM cross-sectional area and ulnar nerve cross-sectional area within the cubital tunnel (r = 0.14). The mean cubital tunnel cross-sectional area was larger in patients with an AEM. Only 4 of the 32 patients with an AEM had findings of ulnar neuritis on MRI. Of the 32 patients with a clinical diagnosis of ulnar neuritis, only 2 had an AEM. CONCLUSIONS: With the elbow in extension, the presence or cross-sectional area of an AEM does not correlate with the area of the ulnar nerve or cubital tunnel. Only a small number of individuals with MRI evidence of an AEM had clinical evidence of ulnar neuropathy. Likewise, MRI evidence of an AEM was found in only a small number of individuals with clinical evidence of ulnar neuropathy.

Pre-stroke glycemia in patients with diabetes.

AIMS: Hyperglycemia in type 2 diabetes mellitus (T2D) remains uncontrolled in approximately 50% of patients in the United States. Uncontrolled T2D is associated with various vascular complications, including stroke. We studied demographic and clinical factors association with pre-stroke glycemia, indicated by glycated hemoglobin (HbA1c), in acute stroke patients with T2D. METHODS: Using a questionnaire, we collected demographic, socioeconomic, and clinical information from 300 acute ischemic and hemorrhagic stroke patients in one hospital. We analyzed factors associated with HbA1c in patients with history of T2D. RESULTS: There were 111 patients with history of T2D and HbA1c measured on admission. In multivariable analyses factors associated with higher HbA1c were treatment with insulin (p=0.05), history of hyperlipidemia (p=0.01), and total cholesterol level (p=0.02). Poor adherence to T2D treatment was associated with higher HbA1c levels (p=0.006) only in a subgroup of patients with HbA1c ≥8%. CONCLUSION: Insulin treatment and hyperlipidemia are associated with higher HbA1c levels in acute stroke patients with T2D. Poor adherence to diabetes treatment is associated with higher HbA1c levels only among patients with HbA1c ≥8%.

Left ventricular hypertrophy in acute stroke patients with known hypertension.

BACKGROUND: Despite effective treatments, hypertension remains uncontrolled in nearly half of the people with hypertension in the United States. Uncontrolled hypertension leads to end organ damage, such as left ventricular hypertrophy (LVH). To identify reasons for uncontrolled hypertension, we interviewed acute stroke patients with a history of hypertension and evaluated for LVH. METHODS: Using a standardized questionnaire, we collected demographic, socioeconomic, and health-care data in 300 acute ischemic and hemorrhagic stroke patients in one hospital. We also collected relevant clinical data from medical records. We analyzed factors associated with echocardiographic LVH as a marker of uncontrolled hypertension in 190 acute stroke patients with a history of hypertension. RESULTS: Overall, 46% (88/190) of patients had LVH. In univariate analysis, lower household income and self-reported poor adherence to hypertension treatment were significantly associated with increased risk of LVH. In multiple logit modeling, only poor adherence to hypertension treatment remained significantly associated with LVH, odds ratio 1.77 (95% CI: 1.01-3.11), p < 0.05. CONCLUSIONS: In acute stroke patients, poor adherence to hypertension treatment is a significant independent predictor of LVH. A clear reason for poor adherence to treatment is elusive in a large proportion of these patients in our study. Further research is needed to identify and develop strategies to combat the key factors responsible for poor adherence to hypertension treatment.

Solution Binding and Structural Analyses Reveal Potential Multidrug Resistance Functions for SAV2435 and CTR107 and Other GyrI-like Proteins.

Multidrug resistance (MDR) refers to the acquired ability of cells to tolerate a broad range of toxic compounds. One mechanism cells employ is to increase the level of expression of efflux pumps for the expulsion of xenobiotics. A key feature uniting efflux-related mechanisms is multidrug (MD) recognition, either by efflux pumps themselves or by their transcriptional regulators. However, models describing MD binding by MDR effectors are incomplete, underscoring the importance of studies focused on the recognition elements and key motifs that dictate polyspecific binding. One such motif is the GyrI-like domain, which is found in several MDR proteins and is postulated to have been adapted for small-molecule binding and signaling. Here we report the solution binding properties and crystal structures of two proteins containing GyrI-like domains, SAV2435 and CTR107, bound to various ligands. Furthermore, we provide a comparison with deposited crystal structures of GyrI-like proteins, revealing key features of GyrI-like domains that not only support polyspecific binding but also are conserved among GyrI-like domains. Together, our studies suggest that GyrI-like domains perform evolutionarily conserved functions connected to multidrug binding and highlight the utility of these types of studies for elucidating mechanisms of MDR.

Solution-Binding and Molecular Docking Approaches Combine to Provide an Expanded View of Multidrug Recognition in the MDR Gene Regulator BmrR.

Solution-binding and molecular docking have been combined with a diverse collection of chemical probes to further elucidate multidrug (MD) recognition in BmrR. Whereas previous efforts have focused on structural elucidations of MD binding, the present study examines features imparted by structure, including the recognition properties of the ligand-pocket, ligand structural requirements, and key factors that define and influence binding. Whereas MD-pockets are generally believed to be featureless and very hydrophobic, log KD-clog P correlations observed for BmrR and other polyspecific proteins suggest polar contributions are required for broad-spectrum recognition of amphipathic ligands. We show that molecular docking simulations recapitulate key features of MD recognition and have been employed to further inform contributions from structure. In addition to elaborating our understanding of the structures and functional roles of pocket elements that dictate broad-spectrum binding, molecular docking has implication additional features that likely play major roles, including ligand dynamics and multiple ligand-binding modes.

Structural contributions to multidrug recognition in the multidrug resistance (MDR) gene regulator, BmrR.

Current views of multidrug (MD) recognition focus on large drug-binding cavities with flexible elements. However, MD recognition in BmrR is supported by a small, rigid drug-binding pocket. Here, a detailed description of MD binding by the noncanonical BmrR protein is offered through the combined use of X-ray and solution studies. Low shape complementarity, suboptimal packing, and efficient burial of a diverse set of ligands is facilitated by an aromatic docking platform formed by a set of conformationally fixed aromatic residues, hydrophobic pincer pair that locks the different drug structures on the adaptable platform surface, and a trio of acidic residues that enables cation selectivity without much regard to ligand structure. Within the binding pocket is a set of BmrR-derived H-bonding donor and acceptors that solvate a wide range of ligand polar substituent arrangements in a manner analogous to aqueous solvent. Energetic analyses of MD binding by BmrR are consistent with structural data. A common binding orientation for the different BmrR ligands is in line with promiscuous allosteric regulation.