George Nikiforidis

Comparison of Nutritional Deficiencies after Roux- en-Y Gastric Bypass and after Biliopancreatic Diversion with Roux-en-Y Gastric Bypass

Background: Patients undergoing either Roux-en-Y gastric bypass (RYGBP) or biliopancreatic diversion (BPD) with RYGBP are at risk of developing metabolic sequelae secondary to malabsorption.We compared the differences in nutritional complications between these two bariatric operations. Methods: A retrospective analysis of a prospective database was done. From June 1994 to December 2001, 243 morbidly obese patients underwent various bariatric procedures at our institution. Of these patients, 79 (BMI 45.6 ± SD=4.9) who underwent RYGBP (gastric pouch 15 ± 5ml, biliopancreatic limb 60-80 cm, alimentary limb 80-100 cm and common limb the remainder of the small intestine), and 95 super obese (BMI 57.2 ± 6.1) who underwent a BPD (gastric pouch 15 ± 5ml, biliopancreatic limb 150-200 cm, common limb 100 cm and alimentary limb the remainder of the small intestine), were selected and studied for the incidence of micronutrient deficiencies and level of serum albumin at yearly intervals postoperatively. A variety of nutritional parameters including Hb, Fe, ferritin, folic acid, vitamin B12 and serum albumin were measured preoperatively and compared postoperatively at 1, 3, 6, 12, 18 and 24 months, and yearly thereafter. Results: Nutritional parameters were compared preoperatively and at similar periods postoperatively. No statistically significant (P <0.05) difference in the occurrence of deficiency was observed between the groups for any of the nutritional parameters studied, except for ferritin, which showed a significant difference at the 2-year follow-up (37.7% low ferritin levels after RYGBP vs. 15.2% after BPD, P =0.0294). All of these deficiencies were mild, without clinical symptomatology and were easily corrected with additional supplementation of the deficient micronutrient, with no need for hospitalization. Regarding serum albumin, there was only one patient with a level below 3 g/dl in the RYGBP group and two in the BPD group.These three patients were hospitalized and received total parenteral nutrition for 3 weeks, without further complications. Conclusion:There was no significant difference in the incidence of deficiency of the nutritional parameters studied, except for ferritin, following RYGBP vs. BPD with RYGBP.The most common deficiencies encountered were of iron and vitamin B12. The incidence of hypoalbuminemia was negligible in both groups, with mean values above 4 g/dl.

CT angiography with three-dimensional techniques for the early diagnosis of intracranial aneurysms. Comparison with intra-arterial DSA and the surgical findings

INTRODUCTION Cerebral CT angiography (CTA) is an established method applied to both the detection and treatment planning of intracranial aneurysms. The aim of our study was to compare CTA and digital subtraction angiography (DSA) findings with the surgical results mainly in patients with acute SAH and to evaluate the clinical usefulness of CTA. MATERIALS AND METHODS During the last 2 years, 82 consecutive patients were admitted under clinical symptoms and signs suggestive of harboring an intracranial aneurysm. CT angiography performed immediately afterwards the plain CT, while DSA was performed within the first 48 h of admission. All aneurysms detected were confirmed during surgery or endovascular embolization. Repeat DSA was performed in all patients having both the initial CTA and the DSA 15 days after the onset of symptoms negative. CT angiograms and conventional angiographies were studied by a consensus of two radiologists for each technique, who performed aneurysm detection, morphological features characterization and evaluation of the technique. RESULTS Surgical or/and endovascular treatment was performed in 45 patients and 53 aneurysms were confirmed. Using 3D-CT angiography, we detected 47 aneurysms in 42 patients. Conventional angiography depicted 43 aneurysms in 39 patients. The sensitivity of CTA for the detection of all aneurysms versus surgery was 88.7%, the specificity 100%, the positive predictive value (PPV) 100%, the negative predictive value (NPV) 80.7% and the accuracy 92.3%. Accordingly, the sensitivity of DSA was 87.8%, the specificity 98%, the PPV 97.7%, the NPV 89.1% and the accuracy 92.9%. Considering aneurysms > or =3 mm, CTA showed a sensitivity ranging from 93.3 to 100%, equal to that of DSA. CONCLUSION Cerebral CT angiography has an equal sensitivity to DSA in the detection of intracranial aneurysms >3 mm. It has also 100% detection rate in AcoA and MCA bifurcation aneurysms, while some locations, like posterior communicating artery aneurysms, remain problematic. The delineating features of each aneurysm are better depicted with CTA due to 3D visualization. The use of digital subtraction angiography as a diagnostic tool can be limited in equivocal cases.

alpha-BLOCKERS FOR THE TREATMENT OF CHRONIC PROSTATITIS IN COMBINATION WITH ANTIBIOTICS

PURPOSE This study was undertaken to evaluate the immediate and long-term effects of the combination of alpha-blockers and antibiotics in the treatment of chronic prostatitis. MATERIALS AND METHODS The patients eligible for study were assigned to 3 groups: group 1--nonprostatodynia, abacterial prostatitis (134), group 2--prostatodynia (72) and group 3--chronic bacterial prostatitis (64). alpha-Blockers were administered to all patients of groups 1 and 2 with demonstrable high maximal urethral closure pressure and typical clinical complaints irrespective of the presence of inflammatory findings in expressed prostatic secretion. alpha-Blockers were given to 50% of patients with bacterial prostatitis. Antibiotics were administered to all patients with positive expressed prostatic secretion cultures, and in half of those with abacterial prostatitis and inflammatory expressed prostatic secretion. Mean followup was 22 months (range 6 months to 3 years). The sign 1-tailed test was used for statistical analysis of data. RESULTS The recurrence rate of bacterial prostatitis was significantly reduced by alpha-blockade (expressed prostatic secretion culture negative) and symptom relief was achieved for many months. For abacterial prostatitis statistical analysis revealed a lower symptom recurrence rate in patients receiving only alpha-blockers in comparison with those treated with a combination of alpha-blockers and antibiotics. CONCLUSIONS The use of alpha-blockers is justified, not only for prostatodynia, but also for abacterial and bacterial prostatitis. In the latter case alpha-blockade not only caused enhanced clinical improvement but also reduced the recurrences as defined by expressed prostatic secretion positive segmental cultures.

In vivo small animal imaging: Current status and future prospects

The use of small animal models in basic and preclinical sciences constitutes an integral part of testing new pharmaceutical agents prior to commercial translation to clinical practice. Whole-body small animal imaging is a particularly elegant and cost-effective experimental platform for the timely validation and commercialization of novel agents from the bench to the bedside. Biomedical imaging is now listed along with genomics, proteomics, and metabolomics as an integral part of biological and medical sciences. Miniaturized versions of clinical diagnostic modalities, including but not limited to microcomputed tomography, micromagnetic resonance tomography, microsingle-photon-emission tomography, micropositron-emission tomography, optical imaging, digital angiography, and ultrasound, have all greatly improved our investigative abilities to longitudinally study various experimental models of human disease in mice and rodents. After an exhaustive literature search, the authors present a concise and critical review of in vivo small animal imaging, focusing on currently available modalities as well as emerging imaging technologies on one side and molecularly targeted contrast agents on the other. Aforementioned scientific topics are analyzed in the context of cancer angiogenesis and innovative antiangiogenic strategies under-the-way to the clinic. Proposed hybrid approaches for diagnosis and targeted site-specific therapy are highlighted to offer an intriguing glimpse of the future.

Improving brain tumor characterization on MRI by probabilistic neural networks and non-linear transformation of textural features

The aim of the present study was to design, implement and evaluate a software system for discriminating between metastatic and primary brain tumors (gliomas and meningiomas) on MRI, employing textural features from routinely taken T1 post-contrast images. The proposed classifier is a modified probabilistic neural network (PNN), incorporating a non-linear least squares features transformation (LSFT) into the PNN classifier. Thirty-six textural features were extracted from each one of 67 T1-weighted post-contrast MR images (21 metastases, 19 meningiomas and 27 gliomas). LSFT enhanced the performance of the PNN, achieving classification accuracies of 95.24% for discriminating between metastatic and primary tumors and 93.48% for distinguishing gliomas from meningiomas. To improve the generalization of the proposed classification system, the external cross-validation method was also used, resulting in 71.43% and 81.25% accuracies in distinguishing metastatic from primary tumors and gliomas from meningiomas, respectively. LSFT improved PNN performance, increased class separability and resulted in dimensionality reduction.

Distal embolism during percutaneous revascularization of infra-aortic arterial occlusive disease: an underestimated phenomenon.

Purpose: To investigate distal embolism during endovascular procedures of the infra-aortic arteries by utilizing a commercial filter basket and unveil any correlation between the baseline clinical and procedural variables and the histopathological findings of the collected particles. Methods: In a prospective study, 48 patients (37 men; mean age 70.8±7.8 years, range 50–83) underwent endoluminal therapy of infra-aortic lesions (stenosis >75% or occlusion; mean lesion length 52.2±38.0 mm) with standard endovascular procedures. A nitinol filter basket (n=50) was employed for distal protection. The collected particles were histopathologically analyzed. The harvested specimens were quantified after digital image post processing. Results: Procedural success of filter-protected revascularization was 93.8%. Three failures included 1 vasospasm, 1 distal embolus, and 1 side-branch occlusion. The total area of retrieved particles per basket was 2.76±6.49 mm2 (range 0.0–40.3). Particles with a major axis >1 and >3 mm were detected in 29 (58.0%) and 6 (12.0%), respectively, of the examined filters. Collected particles consisted primarily of platelets and fibrin conglomerates, trapped erythrocytes, inflammatory cells, and extracellular matrix. Increased lesion length, increased reference vessel diameter, acute thromboses, and total occlusions were positively correlated with higher amounts of captured particles (p<0.05). Multivariate analysis incriminated declotting procedures as the only independent predictor of increased embolic burden (p<0.05). Conclusion: The embolism phenomenon during infra-aortic interventions is frequent and underestimated. The liberated particles consisted primarily of atheromatous plaque elements and thrombus. The reported data might support the application of a protective filter basket in selected subsets of lesions with a riskier embolic profile and whenever declotting procedures are performed.

Automatic vessel lumen segmentation and stent strut detection in intravascular optical coherence tomography

PURPOSE Optical coherence tomography (OCT) is a catheter-based imaging method that employs near-infrared light to produce high-resolution cross-sectional intravascular images. The authors propose a segmentation technique for automatic lumen area extraction and stent strut detection in intravascular OCT images for the purpose of quantitative analysis of neointimal hyperplasia (NIH). METHODS A clinical dataset of frequency-domain OCT scans of the human femoral artery was analyzed. First, a segmentation method based on the Markov random field (MRF) model was employed for lumen area identification. Second, textural and edge information derived from local intensity distribution and continuous wavelet transform (CWT) analysis were integrated to extract the inner luminal contour. Finally, the stent strut positions were detected via the introduction of each strut wavelet response across scales into a feature extraction and classification scheme in order to optimize the strut position detection. RESULTS The inner lumen contour and the position of stent strut were extracted with very high accuracy. Compared with manual segmentation by an expert vascular physician the automatic segmentation had an average overlap value of 0.937 ± 0.045 for all OCT images included in the study. The strut detection accuracy had an area under the curve (AUC) value of 0.95, together with sensitivity and specificity average values of 0.91 and 0.96, respectively. CONCLUSIONS A robust automatic segmentation technique integrating textural and edge information for vessel lumen border extraction and strut detection in intravascular OCT images was designed and presented. The proposed algorithm may be employed for automated quantitative morphological analysis of in-stent neointimal hyperplasia.

A comparative study of surface‐ and volume‐based techniques for the automatic registration between CT and SPECT brain images

Image registration of multimodality images is an essential task in numerous applications in three-dimensional medical image processing. Medical diagnosis can benefit from the complementary information in different modality images. Surface-based registration techniques, while still widely used, were succeeded by volume-based registration algorithms that appear to be theoretically advantageous in terms of reliability and accuracy. Several applications of such algorithms for the registration of CT-MRI, CT-PET, MRI-PET, and SPECT-MRI images have emerged in the literature, using local optimization techniques for the matching of images. Our purpose in this work is the development of automatic techniques for the registration of real CT and SPECT images, based on either surface- or volume-based algorithms. Optimization is achieved using genetic algorithms that are known for their robustness. The two techniques are compared against a well-established method, the Iterative Closest Point-ICP. The correlation coefficient was employed as an independent measure of spatial match, to produce unbiased results. The repeated measures ANOVA indicates the significant impact of the choice of registration method on the magnitude of the correlation (F = 4.968, p = 0.0396). The volume-based method achieves an average correlation coefficient value of 0.454 with a standard deviation of 0.0395, as opposed to an average of 0.380 with a standard deviation of 0.0603 achieved by the surface-based method and an average of 0.396 with a standard deviation equal to 0.0353 achieved by ICP. The volume-based technique performs significantly better compared to both ICP (p<0.05, Neuman Keuls test) and the surface-based technique (p<0.05, Neuman-Keuls test). Surface-based registration and ICP do not differ significantly in performance.

INTERSTITIAL CYSTITIS: BLADDER TRAINING WITH INTRAVESICAL OXYBUTYNIN

PURPOSE We assess the efficacy of intravesical administration of oxybutynin chloride in patients with interstitial cystitis. MATERIALS AND METHODS The study included 36 women with a mean age of 45 years with a diagnosis of interstitial cystitis. Patients were treated with gradual intravesical instillation of saline oxybutynin solution (oxybutynin group) or gradual filling of simple saline (control group). Evaluation parameters consisted of symptom problem index, voids per day, volume per void, functional bladder capacity, volume at first sensation, cystometric bladder capacity and cystometric volume at first sensation. RESULTS Statistically significant improvement of all evaluated parameters was found in both groups. When comparing the outcomes statistically significant improvement of parameters favored the oxybutynin group. CONCLUSIONS Bladder training alone produces a satisfactory result by gradually expanding the bladder, and an additional statistically significant improvement is evident with intravesical oxybutynin.

Adenocarcinoma of the kidney: nephron-sparing surgical approach vs. radical nephrectomy.

Radical nephrectomy has been the traditional surgical treatment for renal cell carcinoma in patients with a normally functioning contralateral kidney. The necessity for a less aggressive surgical approach has emerged in cases in which there is a need to preserve renal function.