Multi-ray medical ultrasound simulation without explicit speckle modelling

Purpose

To develop a medical ultrasound (US) simulation method using T1-weighted magnetic resonance images (MRI) as the input that offers a compromise between low-cost ray-based and high-cost realistic wave-based simulations.

Methods

The proposed method uses a novel multi-ray image formation approach with a virtual phased array transducer probe. A domain model is built from input MR images. Multiple virtual acoustic rays are emerged from each element of the linear transducer array. Reflected and transmitted acoustic energy at discrete points along each ray is computed independently. Simulated US images are computed by fusion of the reflected energy along multiple rays from multiple transducers, while phase delays due to differences in distances to transducers are taken into account. A preliminary implementation using GPUs is presented.

Results

Preliminary results show that the multi-ray approach is capable of generating view point-dependent realistic US images with an inherent Rician distributed speckle pattern automatically. The proposed simulator can reproduce the shadowing artefacts and demonstrates frequency dependence apt for practical training purposes. We also have presented preliminary results towards the utilization of the method for real-time simulations.

Conclusions

The proposed method offers a low-cost near-real-time wave-like simulation of realistic US images from input MR data. It can further be improved to cover the pathological findings using an improved domain model, without any algorithmic updates. Such a domain model would require lesion segmentation or manual embedding of virtual pathologies for training purposes.

     

The prognostic value of neuron-specific enolase in head trauma patients

In recent years, in addition to neurological examination and neuroradiologic examinations, attempts have been made to assess the severity of post-traumatic brain injury and to obtain an early idea of patient prognosis using biochemical markers with a high degree of brain tissue specificity. One such enzyme is neuron-specific enolase (NSE). This study investigates the correlation between serum NSE levels, Glasgow Coma Score, and prognosis measured by Glasgow Outcome Scores in head trauma patients. This was a prospective study conducted with 80 trauma patients presenting to the Emergency Department. Patients were divided into four groups. The first group consisted of patients with general body trauma, but no head trauma. The second group had minor head trauma. The third group had moderate head trauma, and the fourth group had severe head trauma. The relationship between subjects' admission NSE levels and admission and discharge Glasgow Coma Scores (GCS) and Glasgow Outcome Scores (GOS) 1 month later was examined. A receiver operating characteristic (ROC) analysis was performed using a serum NSE cutoff level of 20.52 ng/mL and a GOS of 3 or less as the definition of poor neurologic outcome. There was a significant difference in the NSE levels between group 1 (general trauma) and group 3 (moderate head trauma). There was also a statistically significant difference in NSE levels between group 1 (general trauma) and group 4 (severe head trauma) (p < 0.05). There was a statistically significant inverse relationship between NSE levels and GOS as determined within groups 3 (moderate) and 4 (severe head trauma) (p < 0.05). When NSE levels were compared with admission GCS, it was found that GCS fell as NSE levels rose. There was no significant correlation between NSE and GCS within groups 3 (moderate) or 4 (severe). There was a statistically significant correlation within group 2 (mild) (p < 0.05). By ROC analysis, serum NSE was 87% sensitive and 82.1% specific in predicting poor neurologic outcome in the study patients. The area under the curve was 0.931. This study shows that initial serum NSE levels in moderate and severe head trauma patients correlate inversely with GOS 1 month later, but only within the moderate and severe head trauma groups. However, serum NSE was 87% sensitive and 82.1% specific in predicting poor neurologic outcome in all of the study patients. This derived cutoff value now needs to be prospectively validated.     

Immediate procedural and long-term clinical outcomes following drug-eluting stent implantation to ostial saphenous vein graft lesions

BACKGROUND: Ostial saphenous vein graft (OSVG) lesions were excluded from all the clinical trials demonstrating significantly lower restenosis rates with drug-eluting stents (DES) compared to bare metal stents (BMS). This study aimed to evaluate the efficacy of DES in OSVG lesions by assessing angiographic and 12-month clinical outcomes. METHODS: 70 consecutive patients (70 OSVG lesions) underwent coronary stent implantation between May 2003 and April 2006: 37 lesions received DES and 33 lesions BMS. Endpoints were all cause and cardiovascular mortality, myocardial infarction (MI), target lesion revascularization (TLR), target vessel revascularization (TVR), examined separately and as a combined end-point (major adverse cardiac events, MACE). RESULTS: Procedural (94.6% for DES and 87.9% for BMS) and angiographic (100% for DES and 100% for BMS) success did not differ between the two groups. The only in-hospital events were non-Q wave MI (DES 8.1% versus BMS 12.1%, P=0.69). At 30-day follow-up, there were no other events. Overall, at 1-year follow-up, the BMS group had a higher TLR (30.3% versus 5.4%, P=0.015), TVR (33.3% versus 10.8%, P=0.045) and MACE rate (36.4% versus 10.8%, P=0.024) compared to the DES group. CONCLUSIONS: Drug-eluting stent implantation to OSVG lesions achieves better clinical results than BMS but is still associated with a relatively high incidence (10.8%) of revascularization at 1-year follow-up.     

Investigation of the possibility of using ischemia-modified albumin as a novel and early prognostic marker in cardiac arrest patients after cardiopulmonary resuscitation

Background

Early and accurate prediction of survival to hospital discharge following resuscitation after cardiac arrest (CA) is a major challenge. Our aim was to investigate the levels of ischemia-modified albumin (IMA) and malondialdehyde (MDA) in CA patients and whether IMA levels are valuable early marker of post-cardiopulmonary resuscitation prognosis in CA patients.

Methods

We enrolled 52 in- or out-of-hospital CA patients, with 47 healthy volunteers as the control group (CG). Blood samples were taken for IMA and MDA measurement at the beginning or within 5 min of commencement of CPR. The patients were classified according to the Glasgow Outcome Score (GOS) into a poor outcome group (POG) and a good outcome group (GOG).

Results

Mean IMA levels were higher in POG (0.25 ± 0.07 ABSU) than in GOG (0.19 ± 0.07 ABSU, p = 0.002) and also than CG (0.16 ± 0.04 ABSU, p = 0.0001). The IMA levels were not significantly higher in GOG than in CG (p = 0.32). The mean MDA levels in POG (0.77 ± 0.27 nmol/ml) were comparable to the levels in GOG (0.75 ± 0.18 nmol/ml, p > 0.05), but were significantly higher than in CG (0.60 ± 0.15 nmol/ml, p = 0.001). MDA levels were not significantly higher in GOG than in CG (p = 0.06). The optimum cut-off point for IMA maximizing sensitivity and specificity was 0.235 ABSU, with sensitivity of 65.8% and specificity of 78.6%. The corresponding +PV and −PV were 85.3% and 45.8%, respectively.

Conclusion

In conclusion, though the result may not be applied clinically in every patient, the ischemia-modified albumin may be a valuable prognostic marker in cardiac arrest patients following CPR.     

Short and long-term effects of bacterial translocation due to obstructive jaundice on liver damage

BACKGROUND/AIMS: The present study was conducted to determine if obstructive jaundice promotes bacterial translocation and to evaluate the changes in hepatic histopathology in patients with benign biliary obstruction. METHODOLOGY: Between January 1996 and January 1998, 19 patients treated for benign biliary obstruction were studied. Fourteen patients with symptomatic cholelithiasis were taken as the control group. Patient characteristics, preoperative and post-operative laboratory tests with an interval of 7 days were recorded. In all patients, bile and mesenteric lymph nodes samples were taken for bacterial growth and histopathologic changes were studied on the liver excised during surgery. RESULTS: In the control group, bacterial growth was observed in the bile and mesenteric lymph nodes cultures in one (7.1%) and two patients (14.3%), respectively. In the study group, 8 patients (42%) had positive bile cultures and 12 patients (63.2%) had positive mesenteric lymph nodes cultures, respectively. Histopathologic examination of the liver revealed significant increase in the rate of periductal and portal fibrosis in the jaundiced patients, compared with control group (p < 0.001). Postoperative complications in the study group were wound infection (3 cases), renal failure (2 cases), ARDS (1 cases) and intraabdominal abscess (1 cases). In the control group, one patient had wound infection and one had atelectasis. Two patients with jaundice died of multiple organ failure and respiratory failure. In long-term follow-up (mean 17 months), when sclerosing cholangitis and secondary biliary cirrhosis developed in one patient each in the study group, no long-term complication occurred in the control group. CONCLUSIONS: Our clinical results demonstrate that extrahepatic biliary obstruction promotes bacterial translocation and this process is an important cause of morbidity and mortality in patients with jaundice. Also, obstructive jaundice subsequently leads to significant functional and morphological damage in the liver.     

Comparison of tumor marker CA 242 with CA 19-9 and carcinoembryonic antigen (CEA) in pancreatic cancer

BACKGROUND/AIMS: Although there are a variety of tumor markers used for diagnosis of pancreatic carcinoma, the sensitivity and specificity of those markers have not yet reached an ideal level. The aim of this study was to compare the diagnostic value of CA 242 with CA 19-9 and CEA in the patients with pancreatic cancer. METHODOLOGY: Serum CA 242, CA 19-9 and CEA levels were determined in 135 subjects in the following groups: Pancreatic cancer (n = 40), cholangiocellular carcinoma (n = 15), hepatocellular carcinoma (n = 10), cirrhosis (n = 7), chronic active hepatitis (n = 7), choledochal stone (n = 12), chronic pancreatitis (n = 9), acute pancreatitis (n = 6), and healthy controls (n = 29). RESULTS: An elevated serum CA 242 concentration (> 20 U/mL) was found in 30 out of 40 (70%) (mean; 2163 +/- 838 U/mL) patients with pancreas cancer, in 11 out of 15 patients with cholangiocellular carcinoma (93.3%) (mean 916 +/- 529 U/mL), in none of patients with hepatocellular carcinoma and healthy controls. Slightly elevated CA 242 concentration was found in 6 out of 41 patients with benign hepatobiliary and pancreatic disease (range 0.4-97.8 U/mL) (1 acute pancreatitis, 2 chronic pancreatitis, 1 cirrhosis, 2 choledochal stone). Mean serum CA 242, CA 19-9 and CEA levels of the pancreas cancer group were significantly higher than those of the other groups except the cholangiocellular carcinoma group. There was no significant difference between the stage of pancreas cancer regarding mean serum CA 242, CA 19-9 and CEA level. There was positive correlation between serum CA 242 and CA 19-9 level. In the pancreas cancer, the sensitivity of CA 242, CA 19-9 and CEA was 75%, 80%, 40%, respectively and the specificity of those markers was 85.5%, 67.5% and 73%, respectively. CONCLUSIONS: In conclusion, the advantage of CA 242 compared to CA 19-9 is that its specificity is higher than that of CA 19-9 in the diagnosis of pancreas cancer.     

Effects of microalgae Chlorella species crude extracts on intestinal adaptation in experimental short bowel syndrome

AIM： To evaluate the effects of chlorella crude extract （CCE） on intestinal adaptation in rats subjected to short bowel syndrome （SBS）.
METHODS： Wistar rats weighing 230-260 g were used in the study. After anesthesia a 75% small bowel resection was performed. Rats were randomized and divided into groups. Control group （n = 10）： where 5% dextrose was given through a gastrostomy tube, Enteral nutrition （EN） group （n = 10）： Isocaloric and isonitrogen EN （Alitraq, Abbott, USA）, study group （n = 10）： CCE was administrated through a gastrostomy tube. Rats were sacrificed on the fifteenth pcstoperative day and blood and tissue samples were taken. Histopathologic evaluation, intestinal mucosal protein and DNA levels, intestinal proliferation and apoptosis were determined in intestinal tissues, and total protein, albumin and citrulline levels in blood were studied.
RESULTS： In rats receiving CCE, villus lengthening, crypt depth, mucosal DNA and protein levels, intestinal proliferation, and serum citrulline, protein and albumin levels were found to be significantly higher than those in control group. Apoptosis in CCE treated rats was significantly reduced when compared to EN group rats.
CONCLUSION： CCE has beneficial effects on intestinal adaptation in experimental SBS.     

Assessment of Left Ventricular Systolic Asynchrony in Patients with Clinical Hypothyroidism

Background: Hypothyroidism has a large number of adverse effects on the cardiovascular system such as impaired cardiac contractility. Left ventricular (LV) asynchrony is defined as loss of the simultaneous peak contraction of corresponding cardiac segments. Objective: To assess systolic asynchrony in patients with overt hypothyroidism. Methods: Asynchrony was evaluated in 31 patients with overt hypothyroidism and 26 controls. Clinical hypothyroidism was defined as serum thyroid‐stimulating hormone (TSH) more than 4.2 μIU/mL with reduced free T4 less than 1.10 ng/dL. All the patients and controls were subjected to an echocardiographic study including tissue synchronization imaging (TSI). The time to regional peak systolic velocity (Ts) in LV via the six‐basal‐six‐mid‐segmental model was measured on ejection phase TSI images, and four TSI parameters of systolic asynchrony were computed. LV asynchrony was described by these four TSI parameters. Results: The demographic characteristics and conventional echocardiographic parameters of both groups were similar (except total and LDL cholesterol, TSH, free T3, and free T4). All TSI parameters of LV asynchrony were prolonged in hypothyroid patients compared to controls. The standard deviation (SD) of the 12 LV segments Ts was (53.5 ± 14.1 vs. 29.3 ± 15.5, P < 0.0001); the maximal difference in Ts between any 2 of the 12 LV segments was (154.5 ± 37.3 vs. 91.9 ± 45.2, P < 0.0001); the SD of Ts of the 6 basal LV segments was (47.9 ± 15.9 vs. 27.1 ± 16.4, P < 0.0001); and the maximal difference in Ts between any 2 of the 6 basal LV segments was (118.4 ± 37.9 vs. 69.3 ± 39.0, P < 0.0001). The prevalence of LV asynchrony was significantly higher in patients with hypothyroidism compared with controls (83.9% vs. 26.9%, P < 0.0001). Conclusion: Patients with overt hypothyroidism show evidence of LV asynchrony by TSI. (ECHOCARDIOGRAPHY 2010;27:117‐122)     

The assessment of left ventricular systolic asynchrony in patients with primary hyperparathyroidism

Objectives: Primary hyperparathyroidism (PHP) is associated with a variety of cardiovascular disturbances such as left ventricular (LV) hypertrophy, diastolic cardiac dysfunction, and hypertension. LV asynchrony is defined as the loss of the simultaneous peak contraction of corresponding cardiac segments. The objective of this study was to assess systolic asynchrony in patients with overt hyperparthyroidism. Methods: Asynchrony was evaluated in 22 patients with PHP and 24 controls. All the patients and controls were subjected to a tissue synchronization imaging (TSI). The time to regional peak systolic tissue velocity (Ts) in LV by the six‐basal‐six‐midsegmental model was measured on ejection phase TSI images and four TSI parameters of systolic asynchrony were computed. Results: All TSI parameters of LV asynchrony increased in patients with PHP patients compared to the controls: the standard deviation (SD) of the 12 LV segments Ts (37.3 ± 20.6 vs. 21.5 ± 11.1, P = 0.01); the maximal difference in Ts between any 2 of the 12 LV segments (111.2 ± 59.8 vs. 70.2 ± 32.1, P = 0.01); the SD of the 6 basal LV segments (42.9 ± 36.4 vs. 18.5 ± 13, P = 0.003); and the maximal difference in Ts between any 2 of the 6 basal LV segments (89.6 ± 50.5 vs. 48 ± 31.1, P = 0.003). Conclusion: Patients with PHP show an evidence of LV asynchrony by TSI. Asynchrony may contribute to the harmful cardiovascular effects of PHP. (Echocardiography 2011;28:955‐960)     

Carotid intima-media thickness in patients with isolated coronary artery ectasia

OBJECTIVE: Carotid artery intima-media thickness (IMT) is now widely used as a surrogate marker for atherosclerotic disease. Carotid IMT measured by ultrasound has been shown to be correlated with coronary artery disease as defined by angiography. However, the relation between carotid IMT and isolated coronary artery ectasia (CAE) has not been investigated. The aim of our study was to assess this relation. METHODS: Twenty-five patients with isolated CAE without stenosis and 25 control subjects with angiographically normal coronary arteries were included in this study. These were examined by B-mode ultrasound to measure the IMT at the far wall of the common carotid artery. RESULTS: Patients with isolated CAE had significantly higher carotid IMT compared to control subjects with angiographically normal coronary arteries (0.95+/-0.12 versus 0.71+/-0.10mm respectively, p<0.0001). In addition, we detected a significant positive correlation between the presence of CAE and carotid IMT (r=0.748, p<0.001). CONCLUSION: We have shown for the first time an association between increased carotid IMT and isolated CAE, suggesting that atherosclerosis may be involved in the pathogenesis of isolated CAE in the adult population.