Low yield of ventilation and perfusion imaging for the evaluation of pulmonary embolism after indeterminate CT pulmonary angiography.

PURPOSE: Ventilation and perfusion (VQ) imaging is common following suboptimal CT pulmonary angiogram (CTPA) for pulmonary embolism (PE) evaluation; however, the results of this diagnostic pathway are unclear. The purpose of our study is to determine the incidence of PE diagnosed on VQ scans performed in patients with suboptimal CTPAs. METHODS: One hundred twenty-two suboptimal CTPAs with subsequent VQ scans within 1 week were retrospectively identified. VQ reports utilizing modified â€‹prospective investigation of pulmonary embolism diagnosis (PIOPED) and prospective investigative study of acute pulmonary embolism diagnosis (PISAPED) criteria were evaluated for presence of PE; intermediate probability, high probability, and PE present were considered PE positive. Three hundred consecutive reports of each diagnostic CTPA and diagnostic VQ studies were reviewed to estimate baseline PE positive rates at our institution. These were compared to the positive VQ scan rate after suboptimal CTPA by Fisher's exact test. Reported reason for suboptimal CTPA was noted. When contrast bolus timing was suboptimal, we measured main pulmonary artery (mPA) Hounsfield units (HU). Potential alternative diagnoses in CTPA reports were noted. RESULTS: 97.5% (119/122) of VQ scans following suboptimal CTPA were negative for PE, and 2.5% (3/122) were positive for PE. This was significantly lower than baseline PE positive rate of 10.7% (32/300, p < 0.01) for VQ imaging, and 10.3% (31/300, p < 0.01) for CTPA at our institution. Most (79.5%) CTPAs were suboptimal due to contrast timing. Average mPA density in these cases was 164 ± 61 HU. Most of these studies ruled out central PE. Potential alternative diagnosis was reported in 34/122 (28%) of suboptimal CTPAs, for which pneumonia accounted 59%. CONCLUSION: There is very low incidence of PE diagnosed on VQ imaging performed after suboptimal CTPA. This may be attributed to the ability of most suboptimal CTPAs to rule out central PE.

Diabetic Myonecrosis of the Axilla: A Novel Case With Severe Clinical Features.

Diabetic myonecrosis is a rare and poorly understood complication of long-standing, inadequately controlled diabetes mellitus. Theoretical mechanisms contributing to the pathophysiology of diabetic myonecrosis include microvascular complications due to advanced glycation end-products, ischemia-reperfusion injuries, and dysregulated coagulation-fibrinolysis activity. Case reports of diabetic myonecrosis most commonly describe diabetic patients with chronically poor glycemic control who experience isolated swelling and severe pain in a unilateral lower limb with no signs of infection or systemic toxicity. Due to the rarity of this condition, there are currently no treatment guidelines. This case describes a 58-year-old male with a history of uncontrolled diabetes who presented with diabetic ketoacidosis with mixed hypovolemic and septic shock. Diabetic myonecrosis was incidentally discovered in the patient's right latissimus dorsi with CT imaging and subsequent surgical exploration. Spontaneous diabetic myonecrosis may mimic several other serious conditions and elicit suboptimal management strategies, particularly in the context of atypical presentations.

PURL:Rethinking daily aspirin for primary prevention.

An updated meta-analysis of newer RCTs seems to settle the matter as to whether to use aspirin in individuals with no known history of atherosclerotic CVD.

Application of Diffusion Tensor Imaging in Forecasting Neurological Injury and Recovery after Human Cervical Spinal Cord Injury.

The aim of this study is to determine the strength and accuracy of diffusion tensor imaging (DTI) parameters to predict neurological injury and recovery in adult cervical spinal cord injury (SCI). DTI magnetic resonance imaging (MRI) was performed on 23 acute cervical SCI patients within 12 h after injury and on 45 controls utilizing a rapid DTI sequence (∼5 min). Neurological assessments were conducted from within 24 h of injury up to 6 months utilizing detailed International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) examinations. Spearman correlation and receiver operating characteristic (ROC) analysis were used to identify relationships between the DTI parameters at the lesion epicenter and adjacent regions, with injury severity and recovery. In proximity to the anatomical injury (within one level above and below epicenter), there was significant reduction in fractional anisotropy (FA), and elevation in mean diffusivity (MD) and radial diffusivity (RD). DTI values measured one level rostral to the injury epicenter showed stronger correlations with multiple clinical features at several time-points. Area under the curve (AUC) obtained from ROC analysis showed FA (AUC = 0.77) measured at lesion epicenter, and FA (0.83), MD (0.76), and RD (0.83) values measured immediately rostral (one level above) to epicenter discriminate injury severity. Further, MD (0.78) measured at lesion epicenter, and MD (0.79) and RD (0.74) values measured immediately rostral to epicenter discriminate neurological recovery. DTI indices measured immediately rostral to the anatomical level of injury consistently showed better correlation (moderate to strong) and accuracy in predicting neurological injury (FA, r = -0.51 and RD, r = 0.54) and recovery (MD, r = -0.51) than indices measured at the epicenter. There was weak to moderate correlation of all measures at lesion epicenter in predicting neurological injury (FA: r = -0.48; MD: r = 0.23; RD: r = 0.34; axial diffusivity [AD]: r = 0.02) and recovery (FA: r = 0.27; MD: r = -0.44; RD: r = -0.35; AD: r = -0.34).

Imaging of Spinal Cord Injury: Acute Cervical Spinal Cord Injury, Cervical Spondylotic Myelopathy, and Cord Herniation.

We review the pathophysiology and imaging findings of acute traumatic spinal cord injury (SCI), cervical spondylotic myelopathy, and briefly review the much less common cord herniation as a unique cause of myelopathy. Acute traumatic SCI is devastating to the patient and the costs to society are staggering. There are currently no "cures" for SCI and the only accepted pharmacologic treatment regimen for traumatic SCI is currently being questioned. Evaluation and prognostication of SCI is a demanding area with significant deficiencies, including lack of biomarkers. Accurate classification of SCI is heavily dependent on a good clinical examination, the results of which can vary substantially based upon the patient׳s condition or comorbidities and the skills of the examiner. Moreover, the full extent of a patients׳ neurologic injury may not become apparent for days after injury; by then, therapeutic response may be limited. Although magnetic resonance imaging (MRI) is the best imaging modality for the evaluation of spinal cord parenchyma, conventional MR techniques do not appear to differentiate edema from axonal injury. Recently, it is proposed that in addition to characterizing the anatomic extent of injury, metrics derived from conventional MRI and diffusion tensor imaging, in conjunction with the neurological examination, can serve as a reliable objective biomarker for determination of the extent of neurologic injury and early identification of patients who would benefit from treatment. Cervical spondylosis is a common disorder affecting predominantly the elderly with a potential to narrow the spinal canal and thereby impinge or compress upon the neural elements leading to cervical spondylotic myelopathy and radiculopathy. It is the commonest nontraumatic cause of spinal cord disorder in adults. Imaging plays an important role in grading the severity of spondylosis and detecting cord abnormalities suggesting myelopathy.

CT-guided Cervical Bone Biopsy in 43 Patients: Diagnostic Yield and Safety at Two Large Tertiary Care Hospitals.

RATIONALE AND OBJECTIVES: The cervical spine is a high-risk area for percutaneous biopsy compared to the thoracic and lumbar regions. Biopsy of the cervical spine is less commonly undertaken, and previously published series on diagnostic yield and safety of cervical spine biopsy have been limited to 12 patients or less. The purpose of our study is to further define the diagnostic yield of computed tomography (CT)-guided biopsy for bony lesions identified in the cervical spine, by combining data from two large tertiary care referral centers. METHODS: A retrospective review of an imaging database was performed to identify all percutaneous CT-guided biopsies of the cervical spine performed at two tertiary care hospitals from 2010 to 2015. Core biopsies were obtained whenever possible and supplemented with fine-needle aspiration in some cases. Histopathologic results of the biopsy were recorded, as were changes in subsequent management, need for repeat biopsy, and complications. RESULTS: Forty-three patients underwent CT-guided biopsy of the cervical spine. Sufficient tissue for histopathologic analysis was obtained in 41 out of 43 cases, for a yield of 95%. One case was false-negative and one was deemed insufficient by the pathologist for diagnostic purposes; in both of these cases, only a fine-needle aspiration was obtained. There were no immediate or delayed complications. CONCLUSIONS: Percutaneous biopsy of the cervical spine is a safe and high-yield method of obtaining a tissue diagnosis when performed under image guidance with CT.

Metabolic mystery: aging, obesity, diabetes, and the ventromedial hypothalamus.

We propose that energy balance, glucose homeostasis, and aging are all regulated largely by the same nutrient-sensing neurons in the ventromedial hypothalamus (VMH). Although the central role of these neurons in regulating energy balance is clear, their role in regulating glucose homeostasis has only recently become more clear. This latter function may be most relevant to aging and lifespan by controlling the rate of glucose metabolism. Specifically, glucose-sensing neurons in VMH promote peripheral glucose metabolism, and dietary restriction, by reducing glucose metabolism in these neurons, reduces glucose metabolism of the rest of the body, thereby increasing lifespan. Here we discuss recent studies demonstrating the key role of hypothalamic neurons in driving aging and age-related diseases.

Regulation of peripheral metabolism by substrate partitioning in the brain.

All organisms must adapt to changing nutrient availability, with nutrient surplus promoting glucose metabolism and nutrient deficit promoting alternative fuels (in mammals, mainly free fatty acids). A major function of glucose-sensing neurons in the hypothalamus is to regulate blood glucose. When these neurons sense glucose levels are too low, they activate robust counterregulatory responses to enhance glucose production, primarily from liver, and reduce peripheral metabolism. Some hypothalamic neurons can metabolize free fatty acids via ß-oxidation, and ß-oxidation generally opposes effects of glucose on hypothalamic neurons. Thus hypothalamic ß-oxidation promotes obese phenotypes, including enhanced hepatic glucose output.

Vasoactive intestinal peptide and corticotropin-releasing hormone increase beta-endorphin release and proopiomelanocortin messenger RNA levels in primary cultures of hypothalamic cells: effects of acute and chronic ethanol treatment.

BACKGROUND: beta-Endorphin (beta-EP) neurons are involved in ethanol's action on a variety of brain functions, including positive reinforcement. These neurons are innervated by vasoactive intestinal peptide (VIP)-containing and corticotropin-releasing hormone (CRH)-containing neurons in the hypothalamus. Whether these neuropeptides affect beta-EP neuronal function in the presence or absence of ethanol has not previously been determined. METHODS: The authors determined the effects of VIP and CRH on gene expression and peptide release from beta-EP neurons in primary cultures of mediobasal hypothalamic cells. The effects of receptor antagonists on VIP- and CRH-induced beta-EP release was determined. Furthermore, the authors studied the effects of acute and chronic treatment with ethanol on the response of beta-EP neurons to VIP and CRH. Real-time reverse-transcription polymerase chain reaction was used for messenger RNA (mRNA) detection, and radioimmunoassay was used for hormone measurements. RESULTS: We show that beta-EP neurons responded concentration dependently to VIP and CRH treatments by increasing both beta-EP release and proopiomelanocortin mRNA expression. Simultaneous treatment with a nonspecific receptor antagonist reduced the ability of CRH or VIP to induce beta-EP release from mediobasal hypothalamic cells. Acute treatment with ethanol increased beta-EP neuronal gene expression and the secretory response to CRH and VIP. However, previous exposure to chronic ethanol reduced the CRH and VIP responses of these neurons. CONCLUSIONS: These results indicate that VIP and CRH stimulate beta-EP release from hypothalamic cells in primary cultures and that the stimulatory and adaptive responses of beta-EP neurons to ethanol may involve alteration in the responsiveness of beta-EP-secreting neurons to CRH and VIP.

Opioid antagonist naltrexone disrupts feedback interaction between mu and delta opioid receptors in splenocytes to prevent alcohol inhibition of NK cell function.

Naltrexone, an opioid antagonist, has been used in clinical trials to treat alcoholism. As the opioid peptides beta-endorphin and enkephalin increase splenic NK cell function in laboratory animals, it is anticipated that naltrexone treatment will cause immunosuppression. However, we report in this study that chronic naltrexone administration in laboratory rats increases the cytolytic activity of NK cells. It also prevents alcohol's suppressive effect on these cells. We identified that, in the splenocytes, delta opioid receptor expression is tightly controlled by negative feedback regulation of micro opioid receptors. Naltrexone disrupts this feedback control by reducing micro opioid receptor function, thereby up-regulating delta opioid receptor binding, which results in an enhanced NK cell cytolytic response to delta opioid receptor ligands. We conclude that naltrexone, which has been shown to be a promising agent for the clinical management of alcoholism, may have potential use in the treatment of immune deficiency in alcoholic and nonalcoholic patients.