Advanced image fusion algorithms for Gamma Knife treatment planning. Evaluation and proposal for clinical use.

Image fusion is a process of combining information from multiple sensors. It is a useful tool implemented in the treatment planning programme of Gamma Knife Radiosurgery. In this paper we evaluate advanced image fusion algorithms for Matlab platform and head images. We develop nine level grayscale image fusion methods: average, principal component analysis (PCA), discrete wavelet transform (DWT) and Laplacian, filter - subtract - decimate (FSD), contrast, gradient, morphological pyramid and a shift invariant discrete wavelet transform (SIDWT) method in Matlab platform. We test these methods qualitatively and quantitatively. The quantitative criteria we use are the Root Mean Square Error (RMSE), the Mutual Information (MI), the Standard Deviation (STD), the Entropy (H), the Difference Entropy (DH) and the Cross Entropy (CEN). The qualitative are: natural appearance, brilliance contrast, presence of complementary features and enhancement of common features. Finally we make clinically useful suggestions.     

Clinical outcome after D1 vs D2-3 gastrectomy for treatment of gastric cancer.

BACKGROUND: Clinical benefit from extended lymphadenectomy for gastric cancer remains controversial as a considerable variation exists between results of different studies. METHODS: 562 patients were treated at HUCH between 1987-2003, whereof 223 underwent gastrectomy with curative intent. Of these, 114 patients underwent subtotal/total gastrectomy with D1 (standard) lymphadenectomy and 109 patients had D2-3 (extended) lymph node dissection. The clinical outcome of these patients was analysed retrospectively. RESULTS: The incidence of surgical complications was 33.0% in D2-3 and 16.8% in D1 lymphadenectomy groups (p = 0.008). Abscess was the most common complication (11.0%) among D2-3 operated patients and haemorrhage (4.4%) in D1 group. Hospital mortality was 3.7% in D2-3 and 1.8% in D1 group (p = 0.438). The only statistically significant factor influencing the rate of complications was D2-3 lymphadenectomy (OR 2.620, 95% C.I. 1.375 to 4.991). D2-3 was associated with a longer postoperative hospital stay and operation time, greater blood loss and increased need for blood transfusions compared to D1. The 5-year survival was not statistically different between lymphadenectomy groups. CONCLUSION: It is justified to perform a D2-3 gastrectomy in Europe with a acceptable postoperative mortality but with a significant morbidity. Further studies are needed to assess the value of extended lymphadenectomy in gastric cancer.     

Idiopathic transient osteoporosis of the knee: five cases and revision of literature

Five patients with idiopathic transient osteoporosis were examined. Bone scanning and MRI was helpful in the diagnosis to differentiate of necrosis and all patients recovered completely with conservative and symptomatic treatment. There was no history of trauma in all patients. MRI was realized previously in all cases to confirm the diagnosis and after the resolution of symptomathology.     

Long-term outcomes evaluation after pars defect repair in adult low-grade isthmic spondylolithesis

Adult low-grade isthmic spondylolisthesis is often treated by posterolateral lumbar fusion (PLF), with a certain rate of complications and non-return to work. Alternatives to fusion, like pars defect repair (PDR), were used with encouraging results in young populations and athletes but their outcomes were rarely evaluated for adult patients. This retrospective study quantitatively analysed the long-term outcomes in adult isthmic spondylolisthesis patients treated by PLF or PDR. At a mean follow-up of 9 years, clinical, socio-professional, radiological data and Stauffer-Coventry score were available for 59 patients (39 cases treated by PLF and 20 treated by PDR). The overall clinical outcomes were comparable in both populations (88% in the PDR and 80% in PLF group 1), with a larger proportion of excellent results (56% vs. 10%) and of return to work in the PDR group. Radiological quantitative analysis highlighted stationary evolution and comparable outcomes for the two groups, except for vertebral slip evolution and adjacent level degeneration rate. Abnormal kinematic patterns outlined for PLF patients 20% of pseudarthrosis and 42% of adjacent levels hypermobility and for PDR ones low mobility for the levels adjacent to instrumented vertebra in 40% of cases. Quantified analysis of biomechanical parameters interpreted altogether with clinical outcome, complications and economic burden of the patient, provided accurate objective data for a better appreciation of global outcome, allowing for a preliminary view on long-term outcomes after PDR in adult low-grade isthmic spondylolisthesis, which were not presented in literature until now.     

Does systemic inflammation trigger local exercise-induced oxidative stress in COPD?

Inflammatory abnormalities may be involved in the inadequate basal oxidant/antioxidant balance and local exercise-induced oxidative stress in chronic obstructive pulmonary disease (COPD) patients. The time course of oxidative stress and inflammation was investigated in 10 COPD patients and seven healthy subjects before and after local dynamic quadriceps endurance exercise at 40% of maximal strength. Venous samples were collected before, immediately after and up to 48 h after exercise. At rest, levels of an oxidant released by stimulated phagocytes, the superoxide anion, were significantly higher in patients, as were plasma levels of C-reactive protein, tumour necrosis factor-alpha and interleukin-6, inflammatory markers. An inverse relationship was found between baseline C-reactive protein levels and endurance time in patients. Six hours after exercise, superoxide anion release and levels of protein oxidation products, an index of oxidative stress, increased similarly in both groups, whereas thiobarbituric acid reactive substance levels, another index of oxidative stress, increased significantly only in patients. Plasma nonenzymatic antioxidant and inflammatory cytokine levels were unchanged by the exercise protocol. The increased baseline systemic inflammation in chronic obstructive pulmonary disease patients could be related to disturbed oxidant/antioxidant balance, and, together, these may have triggered the exercise-induced oxidative stress. The absence, however, of local exercise-induced systemic inflammation suggests that additional mechanisms explain local exercise-induced oxidative stress.     

Diagnosis of diffuse and localized arrhythmogenic right ventricular dysplasia by gated blood-pool SPECT.

This study aimed to assess the ability of global and local systolic parameters measured with gated blood-pool SPECT (GBPS) to diagnose and characterize the severity of diffuse or localized arrhythmogenic right ventricular dysplasia (ARVD). METHODS: Fifty-nine subjects with symptomatic ventricular arrhythmias were prospectively included in the study. With the International Society and Federation of Cardiology criteria for ARVD as a gold standard, these subjects were classified as subjects without ARVD (21 control subjects) and patients with localized ARVD (16 patients) or diffuse ARVD (22 patients). Right ventricular volumes, right ventricular ejection fractions (EF), the SD of local EF (sigma-EF), and the SD of the local times of end systole (sigma-TES) were computed from GBPS data and compared among the groups in the study population. RESULTS: sigma-EF did not differ between control subjects and patients with diffuse or localized ARVD. Right ventricular EF and volumes differed between patients with diffuse ARVD and control subjects, with similar areas under the receiver-operating-characteristic curves, but right ventricular EF and volumes failed to differentiate patients with localized ARVD. In contrast, sigma-TES differed between patients with diffuse or localized ARVD and control subjects. Regression analysis showed that the systolic parameter most strongly associated with the diagnosis of ARVD was sigma-TES. The probabilities of a randomly chosen patient in the diffuse ARVD group and of a randomly chosen patient in the localized ARVD group having sigma-TES values greater than that of a randomly chosen control subject were 98.5% and 96.7%, respectively. For the diagnosis of localized ARVD, a threshold of 80 ms for sigma-TES corresponded to sensitivity, specificity, and positive and negative predictive values of 100%, 81%, 80%, and 100%, respectively. CONCLUSION: With GBPS, both diffuse ARVD and localized ARVD can be accurately diagnosed by computing sigma-TES for all of the pixels on the surface of the right ventricle.     

A principal components analysis self-organizing map.

We propose a new self-organizing neural model that performs principal components analysis. It is also related to the adaptive subspace self-organizing map (ASSOM) network, but its training equations are simpler. Experimental results are reported, which show that the new model has better performance than the ASSOM network.     

Analysis of the interbeat interval increment to detect obstructive sleep apnoea/hypopnoea.

The prevalence of obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is underestimated and its diagnosis is costly and restricted to specialised sleep laboratories. The frequency component of interbeat interval increment (III) has been proposed as a simple and inexpensive diagnostic tool in OSAHS. In a set of 150 patients with clinically suspected sleep-related breathing disorder, the actual predictive accuracy of the power spectral density of the III of the very low frequencies (%VLFI) was analysed by comparing with the apnoea/hypopnoea index (AHI), as assessed by synchronised polysomnography. OSAHS was defined in 100 patients according to an AHI>or=15 events.h(-1). Receiver operator characteristic curves built for %VLFI confirmed that this variable was able to separate OSAHS positive from OSAHS negative with statistical significance. Using an appropriate threshold (>4%), %VLFI demonstrated a positive predictive value of 80%. Misclassification of false-positive subjects occurred when the patient presented significant sleep discontinuity and sleep fragmentation (sleep fragmentation index>or=50 events.h(-1)) related to insomnia or periodic limb movements. A power spectral density of the interbeat interval increment of very low frequencies>4% allowed correct classification of obstructive sleep apnoea/hypopnoea syndrome when the clinical history suggested sleep-related breathing disorders and when moderate-to-severe cases are considered. Higher power spectral density of the interbeat interval increment of very low frequencies may also indicate disrupted sleep in the absence of clear clinical symptoms of sleep apnoea/hypopnoea syndrome.