Comparative study of application accuracy of two frameless neuronavigation systems: experimental error assessment quantifying registration methods and clinically influencing factors

Neurosurgical Review - This study aimed at comparing the accuracy of two commercial neuronavigation systems. Error assessment and quantification of clinical factors and surface registration, often...     

Robotic suturing on the FLS model possesses construct validity, is less physically demanding, and is favored by more surgeons compared with laparoscopy

Background  

The value of robotic assistance for intracorporeal suturing is not well defined. We compared robotic suturing with laparoscopic suturing on the FLS model with a large cohort of surgeons.     

Thoracic injuries resulting from intimate partner violence

Intimate partner violence affects individuals in every part of the world regardless of financial status, age, race, religion, nationality and educational background. Women are often the victims of assault by their partners and their presence in emergency departments is well documented. This report highlights the relatively infrequent occurrence of a traumatic pneumothorax as a result of intimate partner physical abuse and aims to emphasize the crucial role all health care professionals need to play if domestic violence is to be recognized early.     

T1‐corrected fat quantification using chemical shift‐based water/fat separation: Application to skeletal muscle

Chemical shift‐based water/fat separation, like iterative decomposition of water and fat with echo asymmetry and least‐squares estimation, has been proposed for quantifying intermuscular adipose tissue. An important confounding factor in iterative decomposition of water and fat with echo asymmetry and least‐squares estimation‐based intermuscular adipose tissue quantification is the large difference in T₁ between muscle and fat, which can cause significant overestimation in the fat fraction. This T₁ bias effect is usually reduced by using small flip angles. T₁‐correction can be performed by using at least two different flip angles and fitting for T₁ of water and fat. In this work, a novel approach for the water/fat separation problem in a dual flip angle experiment is introduced and a new approach for the selection of the two flip angles, labeled as the unequal small flip angle approach, is developed, aiming to improve the noise efficiency of the T₁‐correction step relative to existing approaches. It is shown that the use of flip angles, selected such the muscle water signal is assumed to be T₁‐independent for the first flip angle and the fat signal is assumed to be T₁‐independent for the second flip angle, has superior noise performance to the use of equal small flip angles (no T₁ estimation required) and the use of large flip angles (T₁ estimation required). Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.     

MDCT angiography assessment of renal artery in-stent restenosis: Can we reduce the radiation exposure burden? A feasibility study

Aim

We explored the feasibility of renal artery multidetector computed tomography (MDCT) and detection of in-stent restenosis at low exposure settings.

Patients/methods

Sixteen patients with 19 renal artery stents underwent CT angiography. A biphasic protocol was performed including arteriographic acquisition at standard 120 kVp and a late-arterial scan at 100 kVp (n = 9) or 80 kVp (n = 7). Images were reconstructed under various algorithms. Signal-to-noise and contrast-to-noise ratios (SNR, CNR) were determined within stent, aorta and renal arteries. Image quality and the presence of restenosis were assessed. Volume CT dose-index was recorded and dose reduction (DR%) between phases was calculated.

Results

Ten patients presented with Hounsfield values >250 HU in all segments, phases and reconstructions and were further evaluated. The 120 kVp protocol performed better in all vessels and reconstruction algorithms. SNR at 120 kVp (B31f) did not differ significantly compared to 100 kVp (B31f). CNR within stent was borderline compromised at 100 kVp (p = 0.042). All but two image sets (at 80 kVp) were considered diagnostic. Minor loss of subjective image quality was noticed at 100 kVp. No difference in assessment of restenosis was observed between 120 kVp and the diagnostic low-exposure scans. Mean DR% was estimated 45% at 100 kVp and 77% at 80 kVp.

Conclusions

Renal MDCT angiography and stent-restenosis assessment are feasible at 100 kVp with minor loss of image quality and almost half radiation exposure.     

Long term effects of cardiac resynchronization therapy in non-ambulatory NYHA IV heart failure patients

Background: We aimed at evaluating the long‐term effects of cardiac resynchronization therapy (CRT) in nonambulatory New York Heart Association (NYHA) IV heart failure patients (NAIVHFP). Methods: Eighteen patients, 15 men and three women, eight with ischemic and 10 with nonischemic cardiomyopathy, who underwent biventricular pacemaker implantation while they were in nonambulatory NYHA IV class, were studied. Patients’ age was 58 ± 9 years and left ventricular ejection fraction (LVEF) 18 ± 3 %. Follow‐up data were obtained through review of follow‐up visits notes, stored echocardiographic studies, device interrogation data, and death certificates. Results: After a mean duration of 1223 ± 846 days, 11 patients were alive, including five patients who underwent heart transplantation (OCT) and seven dead. Three of 11 patients who received a CRT‐defibrillator, experienced at least one appropriate discharge, but eventually they either died or received an OCT during follow‐up. Sustained improvements in NYHA class (Z = 2.4, P = 0.015) and 6‐minute walk distance (0 vs 212 ± 95 m, P ? 0.001) were documented after a median duration of 855 days postimplantation. Cumulative proportion of death or OCT at 18 months—when full follow‐up data were available—was 18%, which compared favorably with historical controls. Full echocardiographic and clinical follow‐up data at 12‐months postimplantation were available for 10 patients, documenting a significant reduction in end‐systolic volume (248 ± 82 vs 269 ± 97 mL, P = 0.039). Conclusions: CRT can be safely applied in this subset of extreme severity heart failure patients, achieving encouraging survival rates and reverse remodeling effects. These observations can form an evidence‐based rationale for including NAIVHFP in randomized CRT trials. (PACE 2011; 34:1553–1560)     

Accuracy of the Neuropad test for the diagnosis of distal symmetric polyneuropathy in type 2 diabetes

OBJECTIVE

To estimate the accuracy of Neuropad for the diagnosis and staging of distal symmetric polyneuropathy (DPN) across different stages of neuropathy, using multiple-level likelihood ratios (LRs) to interpret the time necessary to complete the color change of the test.

RESEARCH DESIGN AND METHODS

We conducted a cross-sectional, cohort-type diagnostic accuracy study in 251 consecutive adult type 2 diabetic patients with no peripheral arterial disease or other potential causes of neuropathy, who were recruited between January 2005 and December 2008 from the diabetes outpatient clinics in Alexandroupolis Hospital, Greece. Patients were tested for DPN by means of the neuropathy disability score (NDS) and Neuropad. Multiple-level LRs for time to complete color change were calculated across different stages of neuropathy.

RESULTS

The areas under the curve for the diagnosis of any (NDS of ≥3), at least moderate (NDS of ≥6), or severe (NDS of ≥9) DPN were 0.91, 0.96, and 0.97, respectively. The calculation of multiple-level LRs showed that time to complete color change <360 s suggested the absence of neuropathy. Values between 360 and 1,000 s were indicative of mild neuropathy. Finally, values between 1,000 and 1,200 or >1,200 s were strongly suggestive of moderate or severe DPN, respectively.

CONCLUSIONS

Neuropad could be used as a triage test for the diagnosis and staging of DPN in patients with type 2 diabetes, prompting referral to specialized care setting.Distal symmetric polyneuropathy (DPN) is a major debilitating complication of diabetes (1). DPN is associated with a significant increase in morbidity and represents a cardinal etiologic factor for the development of diabetic foot lesions (1–3). Diagnosis of DPN is based on clinical examination to identify neurologic deficits. Clinical practice recommendations of the American Diabetes Association suggest annual screening of patients with diabetes for DPN and advocate diagnosis by means of simple clinical tests, such as the pin-prick sensation, vibration perception (using a 128-Hz tuning fork), or 10-g monofilament pressure sensation (1,4).Neuropad (Trigocare International, Wiehl, Drabenderhöhe, Germany) is a new diagnostic test with high sensitivity for the diagnosis of DPN (5–9). It is a simple adhesive indicator test that has been found to be suitable for patient self-examination at home (10). Although this holds true for Neuropad interpreted for screening purposes as normal or abnormal after 10 min of application on the plantar aspect of the feet, there is evidence that prolonging the time of observation after application might be useful in increasing the sensitivity for neuropathy and in providing a reliable clue to the severity of neuropathy (6,8). Hence, one might attempt to define multiple-level likelihood ratios (LRs) for Neuropad to increase its diagnostic utility and facilitate prompt specialist referral, where appropriate. The aim of the current study was to examine the accuracy of Neuropad for the diagnosis and staging of DPN across different stages of neuropathy, using multiple-level LRs to interpret the time necessary to complete the color change of the test.