2023 CiteScore: 0.8
pISSN: 2345-5829
eISSN: 2345-5837
Editor-in-Chief:
Mohammad Reza Ay
Chairman:
Saeid Sarkar
Executive Director:
Hossein Ghadiri
Vol 1 No 3 (2014)
Original Article(s)
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Positron emission tomography (PET) has been utilized in numerous aspects of medicine since its introduction and development in 1970s. There has been a rapid improvement in imaging techniques and radiotracers in the last decade, which have enhanced the quality of PET in different biomedical research domains and patient care settings. In this editorial we will discuss applications of PET-computed tomography (CT)/magnetic resonance imaging (MRI) as well as other radiotracers in different variety of malignant and non-malignant diseases such as cardiovascular, central nervous system, inflammatory and systemic diseases and review new concepts applicable to this imaging modality.
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Purpose: Non simultaneous acquisition between CT and PET module can introduce misalignment artefact in cardiac PET/CT imaging due to patient motion. We assessed the clinical impact of patient motion and the resulting mismatch between CT and corresponding CT-based attenuation corrected (CTAC) PET images on apparent myocardial uptake values in cardiac PET/CT imaging.
Methods: The evaluation of patient motion was performed using clinical and experimental phantom studies acquired on the Biograph TP 64 PET/CT scanner. In order to simulate patient motion, CT images were manually shifted from 0 to 20 mm in steps of 5-mm in six different directions. The reconstructed PET images using shifted CT were compared with the original PET images. The assessment of PET images was performed through qualitative interpretation by an experienced nuclear medicine physician and through quantitative analysis using volume of interest based analysis. Moreover, Box and Whisker plots were calculated and bull’s eye view analysis performed. PET images were also reoriented along the short, horizontal and vertical long axis views for a better qualitative interpretation.
Results: A 20-mm shift in the right direction between attenuation and PET emission scans produced mean absolute percentage difference in uptake values in the lateroanterior (33.42±9.07) and lateroinferior (27.39±10.43) segments of the myocardium.
Conclusion: Misalignment could introduce artifactual nonuniformities in apparent myocardial uptake value and the variations were more significant for the misalignment toward the right, feet and head directions, in such a way that even with a 5-mm shift in the CT image, errors in interpretation of PET images could occur. Furthermore, errors in PET uptake estimates were observed for movements as large as 10-mm in the left, posterior and anterior directions. -
Purpose: Force control of robotic instruments is a difficult task due to the uncertainties causedby changes in the instrument’s geometrical and mechanical characteristics during surgery as well as the nonlinear dynamics of the instrument. A new approach based on an intelligent controller is developed to control the force interactions of a robotic surgical instrument with delicate soft tissues. This feature assists the surgeon by providing a safe grasp of soft tissues during dissection or suturing. Besides, by controlling and optimizing the magnitude of the instrument/tissue contact forces, controlled grasp will significantly reduce the surgery trauma.
Method: The controller is devised using a neuro-fuzzy regulator that receives the tracking error and its derivative as inputs, and a PD critic that evaluates the actual pinch force and produces an emotional signal. The controller tunes its parameters by means of minimizing the critic’s output signal, i.e., stress, so that the force tracking error is reduced. Numerical
simulations and experimental tests were performed to evaluate the controller.
Results: Simulation tests revealed that the controller can effectively adapt its rules when the instrument’s geometry and frictional behavior changes. The experiments revealed a settling time of 0.7 s with 3.1% overshoot. In comparison with a PID, the proposed controller reduced the mean squared error (MSE) by 94% for a target constant force, and 24% for a target
sinusoidal trajectory.
Conclusion: the proposed controller showed a superior performance in force control of tissue in safe grasp in comparison with a PID particularly for constant target forces. -
Purpose: The perception of music relies on many culture-specific factors; nevertheless this is processed by physiological and functional attributes of the brain system. The aim of this study is to evaluate the functional activity of brain during the perception of rhythm and melody in Persian classical music using fMRI.
Methods: The test consists of two groups of Persian Modal music scales, frequently called Dastgāh. Mahour and Homayoun, in two parts of non-rhythmic and rhythmic pieces presented on 19 right-handed non-musicians.
Results: The results of this study revealed the brain activities for each of rhythmic and non-rhythmic versions of Mahour and Homayoun Dastgah. For non-rhythmic Mahour, the activation was found in right lingual gyrus, right precuneous cortex, left Inferior frontal gyrus, and left temporal lobe; whereas for rhythmic Mahour, the areas contain left supplementary motor cortex, left superior frontal gyrus, right and left precentral and postcentral gyrus, left supramarginal gyrus, and right temporal pole. The activated regions for non-rhythmic Homayoun include right and left subcallosal cortex, left medial frontal cortex, left anterior cingulate gyrus, and left frontal pole. In contrast, for rhythmic Homayoun, alternative areas including left precentral gyrus, left precuneous cortex, left anterior supramarginal, and left postcentral gyrus were revealed.
Conclusion: rhythmic pieces were shown to activate the areas mostly involved in movement while non-rhythmic pieces related to emotional and memory regions. Although, these results are not consistent totally with the previous findings on western music, they are similar to the outcomes performed on eastern cultural subjects. -
Purpose: Due to the difference in spine curvature in intra-operative and preoperative situations in image guided spine surgery (IGSS), each vertebra needs to be registered separately. This can be done by collecting anatomical landmarks on the patient’s anatomy using a pointer and a tracker, and registering them with corresponding points on the 3D model of CT images. Registering each vertebra using this method can be a tedious and time consuming task. Registering the spine using an articulated model, which incorporates the inter-vertebral transformation between consecutive vertebra, introduces a simple and efficient framework.
Methods: In this paper, a deformation (extension) is applied to the lumbar vertebra of a spine phantom. Local coordinate systems are defined separately for each vertebra in the 3D model reconstructed from CT images before deformation and on the phantom after deformation. The intervertebral transformations for consecutive vertebrae are calculated in the 3D models. Registration is carried out using the local coordinate systems and the intervertebral transformations.
Results: This method was evaluated using point based registration with known corresponding points in both spaces. These results were also compared to those of surface based registration. As indicated by the results, an average improvement of 30% in the registration accuracy was
achieved compared to the surface based registration method with acquired random points.
Conclusion: The proposed method decreases the registration time by eliminating the need to acquire surface points on each individual vertebra. It is also applicable in situations with defected vertebrae where anatomical landmarks are difficult to distinguish. -
Purpose: Gathering an insight into brainstem task in generating auditory response to complex stimuli and its nonlinear behavior can be an important base in auditory system modelling, but no study has been done to demonstrate the nonlinear dynamic behavior of auditory systems considering cABR. This study attends the dynamic modeling of auditory brainstem response to consonant-vowel syllable /da/ using fuzzy logic as nonlinear mapping of the input and output of the system.
Methods: We recorded cABR to /da/ from 40 normal Farsi speaking subjects in response to /da/ with 40ms duration. This data set was divided to train and validation sets. We implemented a fuzzy logic based model for the dynamic extraction of cABR to /da/ for data set. This model includes singltone fuzzifier, product inference engine and weighted center of average defuzzifier. Rule base representing dynamic of signal was generated and, then, firing rate of each rule was calculated and a histogram of rule firing rate was plotted. We selected the important regions of the histogram regarding to firing pattern of the rule. By choosing an appropriate threshold, a secondary rule reduction was done to generate a simplified model; remaining rules were best rules related to important cues of cABR.
Results: This model represents the input-output behavior of the brainstem in generating cABR to consonant-vowel /da/. The total error achieved by cross-validation of the model after an important rule selection is 0.1329 with a variance of 7.08×10-4.
Conclusion: Nonlinear fuzzy based dynamic extraction of cABR signal is a valid approach for generating important features of cABR and a remarkable evidence of these signals can be represented by some spatial rules. -
In this article a new combined method from genetic and fuzzy c-means algorithm (FCM) for discovering the correct number of segments and automatic segmentation of human normal and abnormal brain MR images is proposed.
For reducing the effect of the noise in segmentation process, we use the local and non-local neighbors, and also a new method for finding the appropriate neighbors of the voxels and adjusting their weights. In addition, by decreasing the distance between the data and data cluster centers, the distances between the data from other cluster centers are increased and caused a better and more precise detection of segments boundaries.
The proposed method was applied to 10 clinical MRI data set images. Our experimental results shows that the presented method has a significant improvement compare to other similar methods. -
Purpose: In this report, the preliminary results of the experimental evaluation of the Performance of HiReSPECT scanner have been illustrated.
Methods: In order to assess the capability of the scanner in both planar and tomographic modes, three rats were injected with 99mTc, 99mTc-DMSA, and 99mTc-MDP for thyroid scan, kidney scan and bone scan respectively in order to perform planar imaging. In addition, two rats were injected with 99mTc-MIBI and 99mTc-DMSA to perform cardiac and kidney tomographic imaging, respectively.
Results: Tomographic and planar scans of the rat organs showed that radioactive distribution in cardiac, kidney, bone and thyroid images exhibited detailed physiologic information of the imaged organs. Due to high resolution performance of the scanner, thyroid lobes are well depicted and distinguished from each other.
Conclusion: Results of the evaluation of the planar and tomographic images indicated that HiReSPECT has appropriate imaging capability as an imaging system in biomedical research.
