The assessment for patient with duct-dependent pulmonary circulation (DDPC) during the inter-stage intervals before first
stage palliation commonly includes imaging of the heart with multiple imaging modalities. Recently, three-dimensional
echocardiography (3DE) was found with the ability to delineate cardiac structure that is able to do 360o
rotation. Therefore,
this study aimed at identifying the accuracy of 3DE colour flow in measuring PDA size compared to computer tomography
angiography (CTA). This study involves randomly selected 26 patients with DDPC undergoing CTA for palliation treatment
in one year. The mean patient age is 1.6 ± 0.261 months with mean weight of 3.65 ± 0.82 kg. The full-volume 3DE colour
flow acquisition was performed and analysed offline using Q-lab software. The PDA diameters at the origin as well as the
insertion site were measured. The data obtained by 3DE colour flow data were compared to the CTA, which was taken as
the gold standard. Results showed that the offline analysis of PDA size was feasible in all patients (100%) with the mean
diameter of PDA at the origin on 3DE colour flow and CTA of 0.51 mm ± 0.14 and 0.52 mm ± 0.11, respectively (p = 0.92)
. The PDA diameter at insertion site on 3DE colour flow and CTA was 0.29 mm ± 0.08 and 0.27 mm ± 0.97 respectively (p
= 0.5). Meanwhile, the measurement of 3DE colour flow is comparable to CTA in measurement PDA size. However, the use
of 3DE colour flow in infants with rapid heart rate is yet challenging to 3DE colour flow acquisitions.
Body sizes of patients undergoing x-ray examination vary in body mass index (BMI) and waist circumference (WC). This study aimed to evaluate the relationship between BMI and WC on the image quality of abdominal computed radiography (CR). Anteroposterior supine abdomen projection was conducted on 69 patients from Hospital Raja Perempuan Bainun, Ipoh using a Siemens Multixtop general x-ray unit, and the images were processed with CR Carestream Direct view Max. Samples were categorised into normal BMI (n = 23), overweight (n = 23) and obese (n = 23). Image quality was measured quantitatively in signal-to-noise ratio (SNR) and qualitatively by visual grading analysis (VGA) based on the Commission of the European Communities (CEC) image criteria. Data were analysed by analysis of variance (ANOVA) and Pearson’s correlation for comparison and determining the relationship among BMI, WC and image quality. Results showed a significant difference (p < 0.01) in image quality of VGAmean (normal = 4.40 ± 0.15, overweight = 4.35 ± 0.13, obese = 4.03 ± 0.34) and SNRmean (normal = 60.79 ± 2.19, overweight = 59.66 ± 1.68, obese = 55.78 ± 4.31). A moderate to high negative correlation existed between SNR (r = −0.73), VGA (r = −0.7) with BMI (p < 0.01) and between SNR (r = −0.83), VGA (r = −0.79) with WC (p < 0.01). This study suggests that WC has a higher negative linear relationship than BMI and can be used as an effective image quality predictor for abdominal CR examination.
A functional magnetic resonance imaging (fMRI) study was conducted on 4 healthy male and female subjects to investigate brain activation during passive and active listening. Two different experimental conditions were separately used in this study. The first condition requires the subjects to listen to a simple arithmetic instruction (e.g. one-plus-two-plus-three-plus-four) - passive listening. In the second condition, the subjects were given the same series of arithmetic instruction and were required to listen and perform the calculation - active listening. The data were then analysed using the Statistical Parametric Mapping (SPM5) and the MATLAB 7.4 (R2007a) programming softwares. The results obtained from the fixed (FFX) and random effects analyses (RFX) show that the active-state signal intensity was significantly higher (p < 0.05) than the resting-state signal intensity for both conditions. The results also indicate significant differences (p < 0.001) in brain activation between passive and active listening. The activated cortical regions during passive listening, as obtained from the FFX of the first condition is symmetrical in the left and right temporal and frontal lobes covering the cortical auditory areas. However, for the second condition, which was active listening, more activation occurs in the left hemisphere with a reduction in the number of activated voxels and their signal intensity in the right hemisphere. Activation mainly occurs in the middle temporal gyrus, precentral gyrus, middle frontal gyrus, superior temporal gyrus and several other areas in the frontal lobes. The point of maximum signal intensity has been shifted to a new coordinates during active listening. It is also observed that the magnetic resonance signal intensity and the number of activated voxel in the right and left superior temporal lobes for the second condition have been reduced as compared to that of the first condition. The results obtained strongly suggest the existence of functional specialisation. The results also indicate different networks for the two conditions. These networks clearly pertain to the existence of functional connectivity between activation areas during listening and listening while performing a simple arithmetic task.
The aims of this study were to compare the entrance surface dose (ESD) between anteroposterior (AP) supine with
posteroanterior (PA) prone projection of computed radiography (CR) abdominal examination and to determine the
relationship between body mass index (BMI) and ESD of a patient. AP supine and PA prone projections on the same
patients for CR abdominal examination of intravenous urography (IVU) were acquired on 50 patients at Hospital Raja
Permaisuri Bainun, Ipoh. All the radiographic examinations were carried out on a Siemens Multixtop general x-ray unit
and the images were processed with CR Carestream Direct view Max. Entrance surface dose (ESD) in miligray (mGy)
was measured using optical stimulated luminescence dosimeters (OSLD) calibrated by the Malaysian Nuclear Agency.
Data were analyzed using dependent t-test comparing the AP and PA projections on the same subject and Pearson
correlation was used to determine the relationship between BMI and percentage of reduction of ESD. Results showed a
significant different (p < 0.01) between AP supine (mean ESD = 6.42 ± 7.13 mGy) and PA prone (mean ESD = 3.92 ± 3.56
mGy) projection at all BMI. The BMI has a positive correlation with percentage of reduction of ESD (r = 0. 61) and was
statistically significant (p < 0.01). In conclusion, PA abdomen prone projection significantly reduces the radiation dose
and there is a positive correlation between BMI and percentage of reduction of ESD. The use of PA prone projection for
CR abdominal examination should be considered as the routine projection at all BMIs level. Awareness that as the BMI
increases the ESD also increases at a moderate positive linear relationship.
This study investigated the functional specialisation characteristics of brain in multiple right-hand dominant subjects pertaining to the activation of the cerebral motor cortices evoked by unilateral finger tapping, especially in primary motor (M1) and supplementary motor (SMA) areas. This multiple-subject study used unilateral (UNIright and UNIleft) selfpaced tapping of hand fingers to activate the M1 and SMA. Brain activation characteristics were analysed using statistical parametric mapping (SPM). Activation for UNIright and UNIleft showed the involvement of contralateral and ipsilateral M1 and SMA. A larger activation area but with a lower percentage of signal change (PSC) were observed in the left M1 due to the control on UNIright (4164 voxels at a = 0.001, PSC = 1.650) as compared to the right M1 due to the control on UNIleft (2012 voxels at a = 0.001, PSC = 2.377). This is due to the influence of the tapping rate effects which is greater than what could be produced by the average effects of the dominant and sub-dominant hands. The significantly higher PSC value observed in the right M1 (p < 0.05) is due to a higher control demand used by the brain in coordinating the tapping of the sub-dominant fingers. The findings obtained from this study showed strong evidence of the existence of brain functional specialisation and could be used as baseline references in determining the most probable motor pathways in a sample of subjects.
Objective: This study investigates functional specialisation in, and effective connectivity between the
precentral gyrus (PCG) and supplementary motor area (SMA) in seven right handed female subjects.
Methods: Unimanual (UNIright and UNIleft) and bimanual (BIM) self-paced tapping of hand fingers were
performed by the subjects to activate PCG and SMA. Brain activations and effective connectivity were
analysed using statistical parametric mapping (SPM), dynamic causal modeling (DCM) and Bayesian
model selection (BMS) and were reported based on group fixed (FFX) and random (RFX) effects
analyses. Results: Group results showed that the observed brain activation for UNIright and UNIleft fulfill contralateral behavior of motor coordination with a larger activation area for UNIright. The activation for BIM occurs in both hemispheres with BIMright showing higher extent of activation as compared to BIMleft. Region of interest (ROI) analyses reveal that the number of activated voxel (NOV) and percentage of signal change (PSC) on average is higher in PCG than SMA for all tapping conditions. However, comparing between hemispheres for both UNI and BIM, higher PSC is observed in the right PCG and the left SMA. DCM and BMS results indicate that most subjects prefer PCG as the intrinsic input for UNIright and UNIleft. The input was later found to be bi-directionally connected to SMA for UNIright. The bi-directional model was then used for BIM in the left and right hemispheres. The model was in favour of six out of seven subjects. DCM results for BIM indicate the existence of interhemispheric connectivity between the right and left hemisphere PCG. Conclusion: The findings strongly support the existence of functional specialisation and integration i.e. effective connectivity in human brain during finger tapping and can be used as baselines in determining the probable motor coordination pathways and their connection strength in a population of subjects.
Kajian ke atas sifat kehubungan efektif dalam korteks auditori dilakukan ke atas lima orang subjek Melayu lelaki sihat berumur antara 20 hingga 40 tahun menggunakan pengimejan resonans magnet kefungsian (fMRI), pemetaan statistik berparameter (SPM5) dan pemodelan dinamik penyebab (DCM). Paradigma pengimejan senyap digunakan untuk mengurangkan artifak bunyi pengimbas di atas imej kefungsian. Subjek dikehendaki menumpukan perhatian kepada stimulus hingar putih yang diperdengarkan secara binaural pada keamatan 70 dB lebih tinggi daripada aras pendengaran manusia normal. Pengkhususan kefungsian dikaji menggunakan perisian SPM5 yang berasaskan Matlab melalui analisis kesan malar (FFX), kesan rawak (RFX) dan konjunksi. Analisis individu ke atas semua subjek menunjukkan pengaktifan bilateral yang tidak simetri di antara korteks auditori kanan dan kiri pada kawasan Brodmann (BA)22, 41 dan 42 melibatkan korteks auditori primer dan sekunder. Tiga kawasan auditori di korteks auditori kanan dan kiri tersebut dipilih untuk penentuan kehubungan efektif melalui pembentukan sembilan model rangkaian. Kehubungan efektif ditentukan ke atas empat daripada lima subjek dengan mengecualikan seorang subjek yang mempunyai koordinat BA22 yang terletak terlalu jauh daripada koordinat BA22 yang diperoleh daripada analisis kumpulan. Keputusan DCM menunjukkan kewujudan kehubungan efektif di antara ketiga-tiga kawasan auditori yang dipilih di kedua-dua korteks auditori. Pada korteks auditori kanan, BA42 dikenalpasti sebagai pusat masukan dengan kehubungan efektif satu arah selari BA42 → BA41 dan BA42 → BA22. Walau bagaimanapun, untuk korteks auditori kiri, pusat masukan adalah BA41 dengan kehubungan efektif satu arah selari BA41→BA42 dan BA41→BA22. Kehubungan di antara kawasan auditori yang mengalami pengaktifan mencadangkan kewujudan lintasan isyarat dalam korteks auditori walaupun semasa subjek mendengar bunyi hingar.
In this study, the asymmetry of the main effects of action, background and tonal frequency during a pitch memory processing
were investigated by means of brain activation. Eighteen participants (mean age 27.6 years) were presented with low and
high frequency tones in quiet and in noise. They listen, discriminate and recognize the target tone against the final tone
in a series of four distracting tones. The main effects were studied using the analysis of variance (ANOVA) with action (to
wring (rubber bulb) vs. not to wring), background (in quiet vs. in noise) and frequency (low vs. high) as the factors (and
levels respectively). The main effect of action is in the right pre-central gyrus (PCG), in conformation with its contralateral
behavior. The main effect of background indicated the bilateral primary auditory cortices (PAC) and is right lateralized,
attributable to white noise. The main effect of frequency is also observed in PAC but bilaterally equal and attributable to
low frequency tones. Despite the argument that the temporo-spectral lateralization dichotomy is not especially rigid as
revealed by the main effect of frequency, right lateralization of PAC for the respective main effect of background clearly
demonstrates its functional asymmetry suggesting different perceptual functionality of the right and left PAC.
High sensitivity signal detection for a sparse temporal sampling (STS) functional magnetic resonance imaging (fMRI) is compensated by the increase in the number of scans (Ns) and consequently the scan time. A long scan time would result in fatigue and restlessness in participants, while a short scan time is undesirable for an STS-fMRI due to insufficient Ns for averaging. The purpose of this study was to determine the Ns practically sufficient for a sparse fMRI study. Eighteen participants were presented with white noise during a sparse fMRI scan. The height extent of activation was determined via t statistics and region of interest (ROI) based percentage of signal change (PSC). The t statistics and PSC for Heschl’s gyrus (HG) and superior temporal gyrus (STG) during which the participants listened to the white noise were calculated for different number of scans which were 6, 12, 18, 24, 30 and 36. The t statistics and PSC values calculated for the bilateral HG and STG qualitatively indicated a minimal change over Ns = 12 to 36. Both ROIs showed a consistent common right lateralization of activation for all Ns, indicating the right-hemispheric dominance of auditory cortex in processing white noise stimulus. It was proposed that for a sparse fMRI study, Ns may practically fall between 12 and 36