Increasing iterative reconstruction strength at low tube voltage in coronary CT angiography protocols using 3D-printed and Catphan® 500 phantoms.

PURPOSE: The purpose of this study was to investigate the effect of increasing iterative reconstruction (IR) algorithm strength at different tube voltages in coronary computed tomography angiography (CCTA) protocols using a three-dimensional (3D)-printed and Catphan® 500 phantoms. METHODS: A 3D-printed cardiac insert and Catphan 500 phantoms were scanned using CCTA protocols at 120 and 100 kVp tube voltages. All CT acquisitions were reconstructed using filtered back projection (FBP) and Adaptive Statistical Iterative Reconstruction (ASIR) algorithm at 40% and 60% strengths. Image quality characteristics such as image noise, signal-noise ratio (SNR), contrast-noise ratio (CNR), high spatial resolution, and low contrast resolution were analyzed. RESULTS: There was no significant difference (P > 0.05) between 120 and 100 kVp measures for image noise for FBP vs ASIR 60% (16.6 ± 3.8 vs 16.7 ± 4.8), SNR of ASIR 40% vs ASIR 60% (27.3 ± 5.4 vs 26.4 ± 4.8), and CNR of FBP vs ASIR 40% (31.3 ± 3.9 vs 30.1 ± 4.3), respectively. Based on the Modulation Transfer Function (MTF) analysis, there was a minimal change of image quality for each tube voltage but increases when higher strengths of ASIR were used. The best measure of low contrast detectability was observed at ASIR 60% at 120 kVp. CONCLUSIONS: Changing the IR strength has yielded different image quality noise characteristics. In this study, the use of 100 kVp and ASIR 60% yielded comparable image quality noise characteristics to the standard CCTA protocols using 120 kVp of ASIR 40%. A combination of 3D-printed and Catphan® 500 phantoms could be used to perform CT dose optimization protocols.

Fluid Structure Interaction on Paravalvular Leakage of Transcatheter Aortic Valve Implantation Related to Aortic Stenosis: A Patient-Specific Case.

This study investigated the impact of paravalvular leakage (PVL) in relation to the different valve openings of the transcatheter aortic valve implantation (TAVI) valve using the fluid structure interaction (FSI) approach. Limited studies were found on the subject of FSI with regards to TAVI-PVL condition, which involves both fluid and structural responses in coupling interaction. Hence, further FSI simulation with the two-way coupling method is implemented to investigate the effects of hemodynamics blood flow along the patient-specific aorta model subjected to the interrelationship between PVL and the different valve openings using the established FSI software ANSYS 16.1. A 3D patient-specific aorta model is constructed using MIMICS software. The TAVI valve identical to Edward SAPIEN XT 26 (Edwards Lifesciences, Irvine, California), at different Geometrical Orifice Areas (GOAs), is implanted into the patient's aortic annulus. The leaflet opening of the TAVI valve is drawn according to severity of GOA opening represented in terms of 100%, 80%, 60%, and 40% opening, respectively. The result proved that the smallest percentage of GOA opening produced the highest possibility of PVL, increased the recirculatory flow proximally to the inner wall of the ascending aorta, and produced lower backflow velocity streamlines through the side area of PVL region. Overall, 40% GOA produced 89.17% increment of maximum velocity magnitude, 19.97% of pressure drop, 65.70% of maximum WSS magnitude, and a decrement of 33.62% total displacement magnitude with respect to the 100% GOA.

Evaluation of an integrated 3D-printed phantom for coronary CT angiography using iterative reconstruction algorithm.

INTRODUCTION: 3D-printed imaging phantoms are now increasingly available and used for computed tomography (CT) dose optimisation study and image quality analysis. The aim of this study was to evaluate the integrated 3D-printed cardiac insert phantom when evaluating iterative reconstruction (IR) algorithm in coronary CT angiography (CCTA) protocols. METHODS: The 3D-printed cardiac insert phantom was positioned into a chest phantom and scanned with a 16-slice CT scanner. Acquisitions were performed with CCTA protocols using 120 kVp at four different tube currents, 300, 200, 100 and 50 mA (protocols A, B, C and D, respectively). The image data sets were reconstructed with a filtered back projection (FBP) and three different IR algorithm strengths. The image quality metrics of image noise, signal-noise ratio (SNR) and contrast-noise ratio (CNR) were calculated for each protocol. RESULTS: Decrease in dose levels has significantly increased the image noise, compared to FBP of protocol A (P < 0.001). As a result, the SNR and CNR were significantly decreased (P < 0.001). For FBP, the highest noise with poor SNR and CNR was protocol D with 19.0 ± 1.6 HU, 18.9 ± 2.5 and 25.1 ± 3.6, respectively. For IR algorithm, the highest strength (AIDR3Dstrong ) yielded the lowest noise with excellent SNR and CNR. CONCLUSIONS: The use of IR algorithm and increasing its strengths have reduced noise significantly and thus increased the SNR and CNR when compared to FBP. Therefore, this integrated 3D-printed phantom approach could be used for dose optimisation study and image quality analysis in CCTA protocols.

3D printing in medical imaging and healthcare services.

Three-dimensional (3D) printing technology has demonstrated a huge potential for the future of medicine. Since its introduction, it has been used in various areas, for example building anatomical models, personalising medical devices and implants, aiding in precision medical interventions and the latest development, 3D bioprinting. This commentary is provided to outline the current use of 3D printing in medical imaging and its future directions for advancing the healthcare services.

Development of an organ-specific insert phantom generated using a 3D printer for investigations of cardiac computed tomography protocols.

INTRODUCTION: An ideal organ-specific insert phantom should be able to simulate the anatomical features with appropriate appearances in the resultant computed tomography (CT) images. This study investigated a 3D printing technology to develop a novel and cost-effective cardiac insert phantom derived from volumetric CT image datasets of anthropomorphic chest phantom. METHODS: Cardiac insert volumes were segmented from CT image datasets, derived from an anthropomorphic chest phantom of Lungman N-01 (Kyoto Kagaku, Japan). These segmented datasets were converted to a virtual 3D-isosurface of heart-shaped shell, while two other removable inserts were included using computer-aided design (CAD) software program. This newly designed cardiac insert phantom was later printed by using a fused deposition modelling (FDM) process via a Creatbot DM Plus 3D printer. Then, several selected filling materials, such as contrast media, oil, water and jelly, were loaded into designated spaces in the 3D-printed phantom. The 3D-printed cardiac insert phantom was positioned within the anthropomorphic chest phantom and 30 repeated CT acquisitions performed using a multi-detector scanner at 120-kVp tube potential. Attenuation (Hounsfield Unit, HU) values were measured and compared to the image datasets of real-patient and Catphan® 500 phantom. RESULTS: The output of the 3D-printed cardiac insert phantom was a solid acrylic plastic material, which was strong, light in weight and cost-effective. HU values of the filling materials were comparable to the image datasets of real-patient and Catphan® 500 phantom. CONCLUSIONS: A novel and cost-effective cardiac insert phantom for anthropomorphic chest phantom was developed using volumetric CT image datasets with a 3D printer. Hence, this suggested the printing methodology could be applied to generate other phantoms for CT imaging studies.

Low Risk of CD4 Decline After Immune Recovery in Human Immunodeficiency Virus-Infected Children With Viral Suppression.

BACKGROUND.: Regular CD4 count testing is often used to monitor antiretroviral therapy efficacy. However, this practice may be redundant in children with a suppressed human immunodeficiency virus (HIV) viral load. METHODS: Study end points were as follows: (1) a CD4 count <200 cells/mm3 followed by a CD4 count ≥200 cells/mm3 (transient CD4 <200); (2) CD4 count <200 cells/mm3 confirmed within 6 months (confirmed CD4 <200); and (3) a new or recurrent World Health Organization (WHO) stage 3 or 4 illness (clinical failure). Kaplan-Meier curves and Cox regression were used to evaluate rates and predictors of transient CD4 <200, confirmed CD4 <200, and clinical failure among virally suppressed children aged 5-15 years who were enrolled in the TREAT Asia Pediatric HIV Observational Database. RESULTS: Data from 967 children were included in the analysis. At the time of confirmed viral suppression, median age was 10.2 years, 50.4% of children were female, and 95.4% were perinatally infected with HIV. Median CD4 cell count was 837 cells/mm3, and 54.8% of children were classified as having WHO stage 3 or 4 disease. In total, 18 transient CD4 <200 events, 2 confirmed CD4 <200 events, and10 clinical failures occurred at rates of 0.73 (95% confidence interval [95% CI], 0.46-1.16), 0.08 (95% CI, 0.02-0.32), and 0.40 (95% CI, 0.22-0.75) events per 100 patient-years, respectively. CD4 <500 cells/mm3 at the time of viral suppression confirmation was associated with higher rates of both CD4 outcomes. CONCLUSIONS: Regular CD4 testing may be unnecessary for virally suppressed children aged 5-15 years with CD4 ≥500 cells/mm3.

Histological Evaluation of Hydroxyapatite Granules with and without Platelet-Rich Plasma versus an Autologous Bone Graft: Comparative study of biomaterials used for spinal fusion in a New Zealand white rabbit model.

OBJECTIVES: Hydroxyapatite (HA) has osteoconductive properties and is widely used as a bone graft substitute. Platelet-rich plasma (PRP) is an autologous product with osteoinductive effects. Hypothetically, a combination of both would augment the bone formation effect of HA and widen its application in spinal fusion surgeries. This study aimed to compare new bone formation with HA granules alone and in combination with PRP versus an autologous bone graft during a lumbar intertransverse process spinal fusion. METHODS: A total of 16 adult New Zealand white rabbits underwent single-level bilateral intertransverse process fusion at the L5-L6 vertebrae. One side of the spine received either HA granules alone or a combination of HA granules and PRP, while the contralateral side received an autologous bone graft. Four animals each from the HA group and the HA plus PRP group versus the autograft group were assessed either at six or 16 weeks by undecalcified histology and histomorphometry. The mean percentage of new bone areas over the corresponding fusion masses were compared between groups. RESULTS: No significant difference in new bone formation was observed between the HA and HA plus PRP groups at six or 16 weeks. The autograft group had significantly more new bone formation at six and 16 weeks (P = 0.004 and <0.001, respectively). CONCLUSION: An autologous bone graft remains superior to HA granules, with or without PRP. HA granules demonstrated an excellent osteoconductive scaffold but had poor biodegradability. While PRP enhances the properties of HA granules, these biomaterials do not have a synergistic effect.

Non-Nucleoside Reverse Transcriptase Inhibitor-Based Antiretroviral Therapy in Perinatally HIV-Infected, Treatment-Naïve Adolescents in Asia.

PURPOSE: About a third of untreated, perinatally HIV-infected children reach adolescence. We evaluated the durability and effectiveness of non-nucleoside reverse-transcriptase inhibitor (NNRTI)-based antiretroviral therapy (ART) in this population. METHODS: Data from perinatally HIV-infected, antiretroviral-naïve patients initiated on NNRTI-based ART aged 10-19 years who had ≥6 months of follow-up were analyzed. Competing risk regression was used to assess predictors of NNRTI substitution and clinical failure (World Health Organization Stage 3/4 event or death). Viral suppression was defined as a viral load <400 copies/mL. RESULTS: Data from 534 adolescents met our inclusion criteria (56.2% female; median age at treatment initiation 11.8 years). After 5 years of treatment, median height-for-age z score increased from -2.3 to -1.6, and median CD4+ cell count increased from 131 to 580 cells/mm(3). The proportion of patients with viral suppression after 6 months was 87.6% and remained >80% up to 5 years of follow-up. NNRTI substitution and clinical failure occurred at rates of 4.9 and 1.4 events per 100 patient-years, respectively. Not using cotrimoxazole prophylaxis at ART initiation was associated with NNRTI substitution (hazard ratio [HR], 1.5 vs. using; 95% confidence interval [CI] = 1.0-2.2; p = .05). Baseline CD4+ count ≤200 cells/mm(3) (HR, 3.3 vs. >200; 95% CI = 1.2-8.9; p = .02) and not using cotrimoxazole prophylaxis at ART initiation (HR, 2.1 vs. using; 95% CI = 1.0-4.6; p = .05) were both associated with clinical failure. CONCLUSIONS: Despite late ART initiation, adolescents achieved good rates of catch-up growth, CD4+ count recovery, and virological suppression. Earlier ART initiation and routine cotrimoxazole prophylaxis in this population may help to reduce current rates of NNRTI substitution and clinical failure.

Burden of motorcycle-related injury in Malaysia.

BACKGROUND: Road traffic injury (RTI) contributes to major morbidity and mortality in both developed and developing countries. Most of the injuries are caused by road-related injuries that specifically relate to motorcycle crash. We attempted to conduct a short survey to determine the magnitude of burden related to motorcycle-related RTIs in Malaysia. We hypothesize that motorcycle-related RTI in Malaysia contributes significantly to the health burden in the country. METHODS: The cross-sectional survey involves data searching related to RTI in Malaysia from the relevant agencies such as the Ministry of Health Malaysia, Royal Police Force, and Malaysia Institute of Road Safety Research (MIROS) through their official websites and PubMed search. The three agencies are well established and recognized by the Malaysian government in dealing with data collection for the injury nationwide. The primary aim is to determine the prevalence of motorcycle-related RTI, and secondary outcomes are the overall mortality and the contributing factors. RESULTS: Of the cause of trauma, 80 % is due to RTI, and the most vulnerable road users such as pedestrians and motorcyclists are affected the most. Of all RTI, 70 % is contributed by the motorcycle crash, and there are a significant number of deaths for both rider and pillion rider of the motorcycle than for other types of vehicles. Human error is the main reason to be blamed, specifically the attitude of the riders on the road. CONCLUSIONS: Trauma is one of the common reasons for death and hospitalization in Malaysia. Motorcycle-related RTI in Malaysia contributes significantly to the health burden in Malaysia. The Malaysian government and non-government agencies have worked together seriously in implementing a preventive measure to reduce the incidence and aftermath of motorcycle-related RTI. However, data is still lacking, and every effort is made to increase the amount of research in the field. Strengths of the article are as follows:Latest alarming data on motorcycle-related injuries in the developing country.The data is collected from multi-agencies recognized by ministries in the country.Very limited publication specifically on motorcycle-related injuries is available. Limitations of the article are as follows:The data is only from one country.The statistical data is gathered from a variety of sources, i.e., relevant agencies and authorities and website of the involved ministries.

Performance analysis of an all-optical OFDM system in presence of non-linear phase noise.

The potential for higher spectral efficiency has increased the interest in all-optical orthogonal frequency division multiplexing (OFDM) systems. However, the sensitivity of all-optical OFDM to fiber non-linearity, which causes nonlinear phase noise, is still a major concern. In this paper, an analytical model for estimating the phase noise due to self-phase modulation (SPM), cross-phase modulation (XPM), and four-wave mixing (FWM) in an all-optical OFDM system is presented. The phase noise versus power, distance, and number of subcarriers is evaluated by implementing the mathematical model using Matlab. In order to verify the results, an all-optical OFDM system, that uses coupler-based inverse fast Fourier transform/fast Fourier transform without any nonlinear compensation, is demonstrated by numerical simulation. The system employs 29 subcarriers; each subcarrier is modulated by a 4-QAM or 16-QAM format with a symbol rate of 25 Gsymbol/s. The results indicate that the phase variance due to FWM is dominant over those induced by either SPM or XPM. It is also shown that the minimum phase noise occurs at -3 dBm and -1 dBm for 4-QAM and 16-QAM, respectively. Finally, the error vector magnitude (EVM) versus subcarrier power and symbol rate is quantified using both simulation and the analytical model. It turns out that both EVM results are in good agreement with each other.

Outcomes of human immunodeficiency virus-infected children after anti-retroviral therapy in Malaysia.

AIMS: To describe outcome and examine factors associated with mortality among human immunodeficiency virus (HIV)-infected children in Malaysia after anti-retroviral therapy (ART). METHODS: Retrospective and prospective data collected through March 2009 from children in four different states in Malaysia enrolled in TREAT Asia's Pediatric HIV Observational Database were analysed. RESULTS: Of 347 children in the cohort, only 278 (80.1%) were commenced on ART. The median CD4 count and median age at baseline prior to ART was 272 cells/µL and 4.2 years (interquartile range (IQR): 1.4, 7.4 years), respectively. The median duration of follow-up was 3.7 years (IQR: 1.8, 6.0) with 32 deaths giving a crude mortality rate of 2.86 per 100 child-years. The mortality rate highest in the first 6 months of ART was 10.62 per 100 child-years and declined to 1.83 per 100 child-years thereafter. On univariate analyses, only baseline median CD4 percentage, weight for age z score, height for age z score and anaemia were significantly associated with mortality. Upon including all four of these predictors into a single multivariate model, only weight for age z score remained statistically significantly predictive of mortality. CONCLUSIONS: Children commenced on ART had high mortality in the first 6 months especially in those with low CD4 percentage, wasting and anaemia. Poor nutritional status is an important independent predictor of mortality in this study. Besides initiating ART therapy, nutritional support and intervention must receive the utmost attention.

Characterization of drug-release kinetics in trabecular bone from titania nanotube implants.

PURPOSE: The aim of this study was to investigate the application of the three-dimensional bone bioreactor for studying drug-release kinetics and distribution of drugs in the ex vivo cancellous bone environment, and to demonstrate the application of nanoengineered titanium (Ti) wires generated with titania nanotube (TNT) arrays as drug-releasing implants for local drug delivery METHODS: Nanoengineered Ti wires covered with a layer of TNT arrays implanted in bone were used as a drug-releasing implant. Viable bovine trabecular bone was used as the ex vivo bone substrate embedded with the implants and placed in the bone reactor. A hydrophilic fluorescent dye (rhodamine B) was used as the model drug, loaded inside the TNT-Ti implants, to monitor drug release and transport in trabecular bone. The distribution of released model drug in the bone was monitored throughout the bone structure, and concentration profiles at different vertical (0-5 mm) and horizontal (0-10 mm) distances from the implant surface were obtained at a range of release times from 1 hour to 5 days. RESULTS: Scanning electron microscopy confirmed that well-ordered, vertically aligned nanotube arrays were formed on the surface of prepared TNT-Ti wires. Thermogravimetric analysis proved loading of the model drug and fluorescence spectroscopy was used to show drug-release characteristics in-vitro. The drug release from implants inserted into bone ex vivo showed a consistent gradual release of model drug from the TNT-Ti implants, with a characteristic three-dimensional distribution into the surrounding bone, over a period of 5 days. The parameters including the flow rate of bone culture medium, differences in trabecular microarchitecture between bone samples, and mechanical loading were found to have the most significant influence on drug distribution in the bone. CONCLUSION: These results demonstrate the utility of the Zetos™ system for ex vivo drug-release studies in bone, which can be applied to optimize the delivery of specific therapies and to assist in the design of new drug delivery systems. This method has the potential to provide new knowledge to understand drug distribution in the bone environment and to considerably improve existing technologies for local administration in bone, including solving some critical problems in bone therapy and orthopedic implants.

Characteristics of children hospitalized for pandemic (H1N1) 2009, Malaysia.

To determine effects of pandemic (H1N1) 2009 on children in the tropics, we examined characteristics of children hospitalized for this disease in Malaysia. Of 1,362 children, 51 (3.7%) died, 46 of whom were in an intensive care unit. Although disease was usually mild, ≥ 1 concurrent conditions were associated with higher death rates.

Right-sided Aortic Arch with Aberrant Left Subclavian Artery from Kommerell's Diverticulum.

A previously healthy 52-year-old man had a chest radiograph for medical check-up and found to have a right-sided aortic arch. Computed tomography of the thorax revealed a right-sided aortic arch with aberrant left subclavian artery originated from Kommerell's diverticulum. Barium swallow examination showed compression of the posterior wall of the esophagus. He was asymptomatic and no surgical intervention was performed.

Treatment of a symptomatic forearm muscle herniation with a wrap-around fascia lata graft.

Muscle herniation in the extremity is a well-recognized cause of symptomatic pain on exertion. Only 17 cases involving the upper limb has been previously described, 11 of them involving the anterior compartment of the forearm and only 2 were caused by strenuous exertion. Treatment for this condition ranged from nonsurgical, primary closure with palmaris longus interweave, formal fasciotomy, to closure with a tensor fascia lata graft.This is a study of a 28-year-old man who had a symptomatic swelling on the volar aspect of his left forearm while working on a car-door assembly line that resulted in a significant decreased of his grip strength, work capacity and median nerve symptoms. It did not improve after 6 months of conservative management including hand therapy and splintage. The patient subsequently underwent a tensor fascia lata graft wrap-around. Postoperatively his symptoms resolved with improvement in his grip strength and hand function. The rationale for the treatment option chosen is discussed.

National Suicide Registry Malaysia (NSRM).

To create a nationwide system to capture data on completed suicide in Malaysia i.e. the morbidity, geographic and temporal trends and the population at high risk of suicide. Data from this registry can later be used to stimulate and facilitate further research on suicide. This paper describes the rationale and processes involved in developing a national suicide registry in 2007. The diagnosis of suicide is based on the ICD-10 codes for fatal intentional self-harm (X60-X84). A case report form with an accompanying instruction manual had been prepared to ensure systematic and uniform data collection. State Forensic Pathologist's offices are responsible for data collection in their respective states, and in turn will submit the data to a central data management unit. Data collection began in July 2007 and currently in data cleaning process. Training for source data producers is ongoing. In 2008, the NSRM plans to involve university hospitals into its network as currently only Ministry of Health hospitals are involved. The NSRM will be launching its online application for case registration this year while an overview of results will be available via its public domain at www.nsrm.gov.my beginning 20 April 2008. To efficiently capture the data on suicide, a concerted effort between various agencies is needed. A lot of conceptual work and data base development remains to be done in order to position preventive efforts on a more solid foundation.

Repeated tourniquet testing as a diagnostic tool in dengue infection.

Prospective evaluation of repeated standard tourniquet testing as a diagnostic indicator of dengue infection was done. Included were patients admitted to a children's hospital in Kuala Lumpur on a clinical suspicion of dengue infection based on the World Health Organization (WHO) criteria. A standard method of tourniquet was performed on 79 patients on a daily basis following admission. subjects and negative in the remaining 14 subjects. Fifty-eight subjects were serologically confirmed cases, 4 indeterminate and the remaining 17 subjects had negative serology. For diagnostic classification, 13 had dengue fever, 49 with dengue haemmorhagic fever (DHF) while 17 had non-dengue infection. The sensitivity and specificity of the tourniquet test was 82.8% and 23.5% respectively. The positive predictive value (PPV) was 78.7% while the negative predictive value (NPV) was 28.6%. In addition, the tourniquet test aided in the diagnosis of one-fifth of patients with DHF, who presented with a positive tourniquet test as the only bleeding manifestation. It seems that in a hospital setting, the tourniquet test adds little to the diagnosis of dengue infection/DHF. A positive tourniquet test, repeatedly performed, was found clinically useful as a preliminary screening test in dengue infection as recommended by WHO. However, it was not very specific and had a high false positive rate.