Applying spatial distribution analysis techniques to classification of 3D medical images

OBJECTIVE: The objective of this paper is to classify 3D medical images by analyzing spatial distributions to model and characterize the arrangement of the regions of interest (ROIs) in 3D space. METHODS AND MATERIAL: Two methods are proposed for facilitating such classification. The first method uses measures of similarity, such as the Mahalanobis distance and the Kullback-Leibler (KL) divergence, to compute the difference between spatial probability distributions of ROIs in an image of a new subject and each of the considered classes represented by historical data (e.g., normal versus disease class). A new subject is predicted to belong to the class corresponding to the most similar dataset. The second method employs the maximum likelihood (ML) principle to predict the class that most likely produced the dataset of the new subject. RESULTS: The proposed methods have been experimentally evaluated on three datasets: synthetic data (mixtures of Gaussian distributions), realistic lesion-deficit data (generated by a simulator conforming to a clinical study), and functional MRI activation data obtained from a study designed to explore neuroanatomical correlates of semantic processing in Alzheimer's disease (AD). CONCLUSION: Performed experiments demonstrated that the approaches based on the KL divergence and the ML method provide superior accuracy compared to the Mahalanobis distance. The later technique could still be a method of choice when the distributions differ significantly, since it is faster and less complex. The obtained classification accuracy with errors smaller than 1% supports that useful diagnosis assistance could be achieved assuming sufficiently informative historic data and sufficient information on the new subject.     

Detection and identification of fungi from fungus balls of the maxillary sinus by molecular techniques

The aim of this study was to find a reliable method for the detection and identification of fungi in fungus balls of the maxillary sinus and to evaluate the spectrum of fungi in these samples. One hundred twelve samples were obtained from patients with histologically proven fungal infections; 81 samples were paraffin-embedded tissue sections of the maxillary sinus. In 31 cases, sinus contents without paraffin embedding were sent for investigation. PCR amplification with universal fungal primers for 28S ribosomal DNA and amplicon identification by hybridization with species-specific probes for Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, Aspergillus terreus, Aspergillus glaucus, Pseudallescheria boydii, Candida albicans, and Candida glabrata were performed for all samples. Furthermore, PCR products were sequenced. Fresh samples were also cultivated. Fungal DNA was detected in all of the fresh samples but only in 71 paraffin-embedded tissue samples (87.7%). Sequence analysis was the most sensitive technique, as results could be obtained for 28 (90.3%) fresh samples by this method in comparison to 24 (77.4%) samples by hybridization and 16 (51.6%) samples by culture. However, sequence analysis delivered a result for only 36 (50.7%) of the paraffin-embedded specimens. Hybridization showed reliable results for A. fumigatus, which proved to be the most common agent in fungus balls of the maxillary sinus. Other Aspergillus species and other genera were rarely found.     

Is Robotic Revisional Bariatric Surgery Justified? An MBSAQIP Analysis

Background

The laparoscopic approach is utilized in greater than 90% of bariatric surgeries. With the growing prevalence of robotic-assisted surgery in bariatrics, there has been limited consensus on the superiority of either laparoscopic or robotic approaches, especially in revisional procedures (conversion from sleeve gastrectomy (SG) to Roux-en-Y gastric bypass (RYGB)).

Methods

A retrospective analysis was performed of the MBSAQIP PUF database of patients who underwent conversion from SG to RYGB procedures in either laparoscopic or robotic-assisted approaches. The groups underwent 2:1 propensity matching and primary outcomes included post-conversion days until discharge (POD), conversion operation length, total and major morbidity, 30-day readmission, 30-day reoperation, 30-day reintervention, and 30-day mortality after conversion.

Results

After 2:1 propensity score matching, 3411 patients (2274 laparoscopic vs 1137 robotic) were included in the study. Intraoperatively, no significant difference was found in total morbidity (6.5% lap vs 5.9% robotic) or major morbidity (1.9% lap vs 1.7% robotic); however, the operative times were significantly longer robotically (126 min vs 164 min). Post-operatively, no significant differences were found in discharge day (1.8 lap vs 1.8 robotic), 30-day readmission (7.6% lap vs 8.6% robotic), reoperation rate (2.9% lap vs 3.7% robotic), additional intervention rate (2.5% lap vs 3.3% robotic), or 30-day mortality (0.1% vs 0.1%).

Conclusion

There is no significant difference in perioperative or intraoperative outcomes between laparoscopic and robotic-assisted SG to RYGB conversion procedures other than a longer operative time in the robotic approach, suggesting increased efficiency with the laparoscopic approach.

Graphical abstract

     

Reversal of granulocyte adherence to nylon fibers using local anesthetic agents: possible application to filtration leukapheresis

The effects of the cationic anesthetic agents tetracaine and lidocaine on granulocyte function, morphology, and adherence to nylon fibers were studied in an attempt to improve current methods of granulocyte collection by filtration leukapheresis (FL). When dissolved in acid- citrate-dextrose (ACD) plasma, these drugs significantly increased granulocyte elution from the fibers in a dose-related fashion. Granulocytes exposed to tetracaine and lidocaine remained more than 95% viable, retained normal bactericidal capacity after the drugs were washed from the cells, and had preserved membrane integrity, as evidenced by the normal ultrastructural appearance of tetracaine- exposed cells and an absence of leakage of lysozyme or lactic dehydrogenase. Granulocytes eluted with the anesthetic agents were rounded in shape with a reduction in the number of filopodial cytoplasmic projections and a relative absence of cytoplasmic vacuolization when compared to granulocytes eluted with ACD plasma alone. Dose-related inhibition of phagocytosis and adherence, which was largely reversible after washing the granulocytes, was noted. Greater than 95% of the lidocaine could be removed from the eluate with a single centrifugation and resuspension, indicating that granulocytes prepared by FL with anesthetic-enhanced elution could be potentially transfusable.     

Estimation of the enterogastric reflux by modified scintigraphic method

BACKGROUND/AIMS: The aim of the study was to introduce the chosen and modified model of the nuclear medicine method for the detection and quantification of enterogastric reflux, as well as evaluation of its clinical validity. METHODOLOGY: The study was performed in 172 patients: with gastric and duodenal ulcer, after Billroth I and Billroth II gastrectomy, with gastroesophageal reflux, after cholecystectomy, with chronic cholecystitis and chronic duodenal disease. Acquisition was performed with a gamma camera, during 90 min after intravenous application of 185MBq 99mTc-Dietil IDA. Test meal was given in the 30th minute, while the gastric region was marked at the end of the study. On the basis of the radioactivity changes in the regions of the stomach and hepatobiliary system, the presence of enterogastric reflux was determined and its index calculated. RESULTS: In all the groups of patients, values were significantly higher than in the controls (P < 0.05). The most frequent occurrence and the largest quantity of reflux was present in patients after Billroth II gastrectomy with significantly different values from other groups of patients (P < 0.05). CONCLUSIONS: The obtained results approve clinical value of the chosen and modified scintigraphy of enterogastric reflux, as a non-invasive and physiological method, which provides exact data about its presence and quantity.     

Platelets inhibit the induction of nitric oxide synthesis by interleukin-1 beta in vascular smooth muscle cells

We have investigated the role of platelets in regulating the hemostatic and vasomotor properties of vascular smooth muscle. Experiments were performed to examine the effect of the releasate from activated platelets on the production of nitric oxide from interleukin-1 beta (IL- 1 beta)-treated cultured rat aortic smooth muscle cells. Treatment of vascular smooth muscle cells with IL-1 beta resulted in significant accumulation of nitrite in the culture media and in marked elevation of intracellular cyclic guanosine monophosphate (GMP) levels. The releasate from collagen-aggregated platelets blocked the IL-1 beta- mediated production of nitrite and the accumulation of cyclic GMP in smooth muscle cells in a platelet number-dependent manner. In functional assays, the perfusates from columns containing IL-1 beta- treated smooth muscle cells relaxed detector blood vessels without endothelium and the addition of IL-1 beta-treated smooth muscle cells to suspensions of platelets inhibited their thrombin-induced aggregation. The simultaneous treatment of smooth muscle cells with IL- 1 beta and the platelet releasate abolished both the vasorelaxing activities of the perfusates and the inhibition of platelet aggregation. Platelet releasates treated with a neutralizing antibody to platelet-derived growth factor (PDGF) failed to block IL-1 beta- induced nitric oxide production by the smooth muscle cells, as measured by both biochemical and functional assays. The platelet releasate from a patient with gray platelet syndrome likewise failed to block IL-1 beta-induced nitrite release by smooth muscle cells. These results demonstrate that platelets downregulate the production of nitric oxide by IL-1 beta-treated vascular smooth muscle cells through the release of PDGF. This effect may represent a novel mechanism by which platelets regulate vasomotor tone and thrombus formation at sites of vascular injury.     

Thromboembolic complications after spinal surgery in trauma patients

Background Deep venous thrombosis (DVT) and pulmonary embolism (PE) may be significant complications following spinal surgery. The incidence rate ranges from 0.5% to 2.5% in patients with symptomatic thromboembolic disease and up to 15% in patients with non-symptomatic thrombotic complications. We determined the incidence of symptomatic thromboembolism after spinal surgery in patients with postoperative systemic prophylaxis and investigated general and specific risk factors for development of this disease.

Patients and methods We analyzed the clinical records of 978 patients who had undergone surgery of the spine because of trauma and who had been admitted to our level-I trauma center between 1980 and 2004. Spinal procedures included anterior and/or posterior spinal fusion, video-assisted thoracoscopic fusion, and spinal decompression. Symptomatic thromboembolic disease was diagnosed when patients showed significant clinical signs or symptoms of DVT or PE. In cases of DVT, diagnosis was confirmed by duplex scan of the lower limbs; in cases of PE, diagnosis was confirmed by CT-scanning of the thorax or at post mortem.

Results The incidence rate of symptomatic thromboembolic complications was 2.2% (n 22). 17 patients showed clinical signs of deep venous thrombosis, with 4 of them developing pulmonary embolism subsequently. The other 5 patients developed pulmonary embolism without prior clinical signs of deep venous thrombosis. 6 patients died because of thromboembolic disease. Thromboembolic complications were more frequent in older patients and among males, as well as in patients with regular tobacco consumption and obesity. Thromboembolic complications were also seen more frequently in patients with surgical procedures at the lumbar spine, in patients with anterior spinal fusion, and in those with motor deficits in the lower extremities.

Interpretation We found a rather low rate of clinically significant thromboembolic complications after spinal surgery because of trauma, compared to the results reported in the literature. Level of spinal surgery, surgical approach, and motor deficits in the lower extremities were identified as specific risk factors for DVT or PE. Age, sex, obesity and regular smoking were identified as general risk factors.