Intensity-based 3D local image registration

In this paper we present a pre-processing stage for an automated volumetric CT stroke image diagnosis system. It concerns the automatic intensity-based 3D image registration of non-contrast CT (NCCT) to CT angiography (CTA) images. The NCCT were acquired with a gantry tilt and hence they are first tilt corrected. After the tilt correction process, the NCCT images are then registered to the CTA image. The accuracy of image registration is measured by the overlap of the segmented skull from both images. The limitation of the current implementation is computing time which should be improved for a clinical application of the method.

The effects of out-of-plane rotations on two dimensional portal image registration in conformal radiotherapy of the prostate

Medical image registration plays an essential role in subsequent image processing and analysis. The demand of direct 3D registration of volumetric image data has been arisen due to the increasing amount of medical image data. This paper investigates a fast volumetric image registration algorithm based on an incompressible viscous fluid model. While direct extension and implementation from 2D fluid registration is inaccessible, we develop numerical techniques to accelerate the computation based on the alternating direction implicit (ADI) scheme. In consequence, the computational complexity is significantly reduced from O(N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) to O(N). Not only does the computation time expedite, but the memory usage is also cut down. Massive experiments with both simulated and clinical magnetic resonance (MR) image data were administered to qualitatively and quantitatively evaluate the proposed 3D image registration framework. Experimental results suggested that our accelerated image registration algorithm produced high accuracy on both 2D and 3D image registration scenarios and outperformed competing methods. We believe that the proposed volumetric image registration scheme is promising in processing MR image volumes for further medical applications.

712 Correlating Current Pathways With Myocardial Fiber Orientation Through Fusion of Data From Current Density and Diffusion Tensor Imaging

The purpose of this study is to present a virtual planning protocol based on the database and three-dimensional (3D) image registration technology for the restoration of the total nasal defect, and evaluate its feasibility and clinical efficacy. Patients were scanned with a FaceScan to obtain the 3D facial model which was stored in an Extensible Neuroimaging Archive Toolkit (XNAT) database. Personalized search and similarity evaluation were performed in the database to find a normal 3D facial model with the highest similarity to the patient's. Then, the 2 models were imported into the dedicated software for 3D image registration to get the 3D model of the nasal defect part and the preoperative planning 3D facial model of virtual restoration. Subsequently, the dimensionality reduction algorithm was conducted to transform the 3D model of the nasal defect to a 2D flatten one for determining the scope of the forehead flap during surgery. Four weeks after the insetting surgery of forehead flap pedicle, the postoperative 3D facial model was gained. At last, the clinical efficacy was evaluated by comparing the difference between the preoperative planning and postoperative 3D facial model. The nasal shapes of the patients were good after the operation, and the results revealed that the maximum error was ranging from 3.12 to 4.07 mm with the mean error from 0.92 to 1.04 mm. The database and 3D image registration technology provide a new approach for precisely determining the scope of total nasal defect and the forehead flap, which may be used for reference in the accurate restoration of other facial soft tissue defects.

Objective: to evaluate pharmacoeconomic advantages of the application of magnetic resonance imaging (MRI) with hepatobiliary-specific contrast agent – gadoxetic acid in addition to contrast-enhanced computed tomography (CT) in the diagnosis of hepatocellular carcinoma (HCC).Material and methods. We performed the modeling and obtained the results of the pharmacoeconomic study: effectiveness analysis, cost analysis, and cost-effectiveness analysis. The cost analysis included only direct medical costs (the cost of contrast-enhanced CT, gadolinium-based contrast agent (GBCA) for MRI, and therapy per a patient with verified HCC diagnosis after diagnostic procedures). The financing was performed from the Compulsary Health Insurance Fund. The calculations were made per 1 patient.Results. The effectiveness analysis showed that the diagnostic scheme CT + MRI with gadoxetic acid was the most effective complex for the diagnosis of HCC because its application provided 50% of patients with 5-year overall survival (4.8 years), which was significantly higher than in patients who were diagnosed HCC with CT + MRI with extracellular GBCA (2.3 years) or CT (3.7 years). The cost-effectiveness analysis showed that the diagnostic scheme with gadoxetic acid was dominant because each disability-adjusted life year required fewer costs (14 862 rubles) in comparison with CT + MRI with extracellular GBCA (25 293 rubles) or CT (46 540 rubles). According to the results of the incremental cost-effectiveness ratio analysis, the application of the diagnostic complex with gadoxetic acid was characterized by the lowest rate of additional costs per 1 disability-adjusted life year.Conclusion. The pharmacoeconomic study showed that the application of MRI with a hepatospecific contrasting agent – gadoxetic acid in addition to contrast-enhanced CT was an effective and economically beneficial method of early HCC diagnosis.

In image-guided adaptive radiotherapy, it is important to have the capability to automatically and accurately delineate the rectal wall, which is a major dose-limiting organ in prostate cancer radiotherapy. As image registration is a process to find the spatial correspondence between two images, a major challenge in intensity-based deformable image registration is to deal with the situation where no correspondence exists for some objects between the two images to be registered. One example is the variation of rectal contents due to the presence and absence of bowel gas. The intensity-based deformable image registration methods alone cannot create the correct spatial transformation if there is no correspondence between the source and target images. In this study we implemented an automatic image intensity modification procedure to create artificial gas pockets in the planning computed tomography (CT) images. A diffusion-based deformable image registration algorithm was developed to use an adaptive smoothing algorithm to better handle large organ deformations. The process was tested in 15 prostate cancer cases and 30 daily CT images containing the largest distended rectums. The manually delineated rectums agreed well with the autodelineated rectums when using the image-intensity modification procedure.

Objective: This study aimed to assess the clinical applicability of magnetic resonance imaging (MRI) for the early diagnosis of common peroneal neuropathy (CPNe).Methods: Over three years, the authors have treated 58 patients with CPNe. All patients had clinical or neurophysiological confirmation of CPNe. Among them, 35 (60%) patients underwent axial knee MRI with a 1.5-Tesla scanner. These 35 patients were selected for study and were classified into three groups according to the time of examination after the occurrence of dropped foot―acute, subacute, and chronic onset groups. According to muscle appearances (normal, edematous change, and atrophy), we diagnosed them with CPNe, except for those with normal morphology. We evaluated the applicability of MRI in the diagnosis of CPNe compared to that of electromyography (EMG).Results: The 18, 11, and six cases were included in the acute, subacute, and chronic onset groups, respectively. In the acute onset group, three cases had normal muscle appearance, while 15 cases had edematous changes in the affected muscles. In the subacute onset group, eight cases had edematous changes, while three cases showed muscle atrophy. In the chronic onset group, six cases had muscle atrophy. CPNe could be diagnosed using MRI in about 91% (32/35) of all the cases. Excluding the chronologically chronic stage, diagnosis rate was approximately 89%(26/29) of all the cases. However, only in 27 cases (77%) denervation potentials were presented on EMG.Conclusion: According to our results, MRI is a helpful diagnostic modality, especially in the early stage of CPNe, and may lead to proper management.

BackgroundTo explore the application of magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) in the diagnosis of hypoxic-ischemic encephalopathy and kernicterus in premature infants.MethodsFifty-eight premature infants with hypoxic-ischemic encephalopathy and fifty-eight premature infants with kernicterus who were examined and treated in our hospital between January 2018 and January 2021 were assigned to the observation group or the control group. All patients were examined by MRI imaging and DWI imaging, and the examination results were compared between the two groups.ResultsNo significant differences were found in sensitivity, specificity, positive predictive value, or negative predictive value between the observation group and the control group (P>0.05). MRI could clearly visualize the signal changes of patients, whereas DWI did not show any signal changes. There was no significant difference between MRI and DWI in the diagnosis of hypoxic-ischemic encephalopathy in premature infants. Further, there was no significant difference in the diagnostic performance of MRI between the observation group and the control group (P>0.05). However, the diagnostic performance of DWI in the control group was better than that in the observation group, and the difference was statistically significant (P<0.05).ConclusionsMRI and DWI imaging have high detection rates for the diagnosis of hypoxic-ischemic encephalopathy and kernicterus in premature infants. These imaging methods can benefit the treatment of premature infants and have important clinical application value.

The cerebral venous system plays a critical role in fetal brain development. Accurate assessment of the structure and function of the cerebral venous system is essential for early diagnosing fetal conditions related to cerebral venous system abnormalities and monitoring the brain health of fetuses in high-risk pregnancies. It provides reliable prenatal counseling to parents, enabling them to make informed prenatal choices. However, there is a lack of research on the fetal cerebral venous system, making its developmental process poorly understood. In recent years, the application of magnetic resonance imaging (MRI) has become increasingly mature in the field of fetal cranial and brain disorders due to its non-invasive characteristics and high sensitivity. The examination sequences are constantly being updated, playing an increasingly important role in the evaluation of the fetal cerebral venous system. This article presents the application value of MRI in the diagnosis of common fetal cerebral venous system abnormalities. It specifically reviews the application of conventional prenatal MRI, susceptibility weighted imaging (SWI), and quantitative susceptibility mapping (QSM) in the assessment of the structure and function of the fetal cerebral venous system. Additionally, the article provides an overview of the prospects and potential future directions in this field.

This research describes signal processing techniques useful to highlight and contrast enhance human brain vessels detected with magnetic resonance imaging (MRI). The signal is here represented as multiplication between image intensity and the sum of second‐order partial derivatives of the model function fitted to MRI data. The implication of this novel and different concept is the introduction of the new variable called intensity‐curvature. The following six intensity‐curvature measurement approaches (ICMAs) can hence be calculated: classic‐curvature, intensity‐curvature functional (ICF), signal resilient to interpolation, resilient curvature, and intensity‐curvature terms (ICTs) before and after interpolation. This paper explores the use of ICMAs with applications in human brain MRI. Studying vasculature of the human brain is possible through two techniques apt to measure human brain MRI intensity‐curvature. The first technique is the inverse Fourier transformation procedure, which uses as k‐space filters the ICTs before and after interpolation. The other technique is called intensity‐curvature masking procedure, and it raises each ICMA to a power determining a nonlinear combination of ICMAs to sum up to MRI image intensity on a pixel‐by‐pixel basis. This paper reports that ICTs are k‐space filters, ICF is a high‐pass filter, and ICMAs are mask images. The major implication of these methodologies is effective k‐space filtering. The techniques here presented support visualization of human brain vessels. The advantage of these methods relies in speed of computation.

Objective To evaluate the effect of setup errors on the 2D image projection and image registration, and then propose an improved registration method based on mutual information. Methods An anthropomorphic head phantom was used to simulate the rotational and translational setup errors. The geometric disparities were reflected by the changes of mutual information. Known setup errors were intentionally introduced to twenty cases divided into two groups demarcated by 3 mm translation error and 3° rotation error: ten cases with larger errors and ten with smaller errors. Then the anterior-posterior and lateral portal images were captured by the electronic portal imaging device (EPID), based on which the setup errors were calculated using two mutual information registration method respectively: the vender provided one, and the improved method as proposed. The calculated errors were compared with the actual setup errors to evaluate robustness of the method. Results For the ten cases with smaller setup errors, the average translational registration disparities using the conventional method were 0.3, 0.4, and 0.3 mm in x, y and z directions respectively. The rotational disagreements were 0.4° in both x and z directions. The average time consumption was 28.7 s. The corresponding discrepancies analyzed using the improved method were 0.3, 0.4, 0.3 mm, 0.5° and 0.4°, respectively. On average, 31.1 s was needed for registration. For the ten cases with larger setup errors, the mean disparities of the conventional method were 0.9, 0.7, 0.8 mm, 0.9° and 0.8°, 29.9 s taken on average. The corresponding result of the improved method was 0.5, 0.4, 0.5 mm, 0.6° and 0.5°, 33.2 s taken on average. Conclusions Regarding smaller setup errors, the two methods showed little difference and both had good performance in image registration accuracy. For larger setup errors, however, the improved mutual information registration method exhibited significantly higher accuracy than the conventional method, at cost of clinically acceptable registration time. Key words: Setup errors; Electronic portal imaging device; Portal image; Image registration

Human in vivo molecular imaging with positron emission tomography (PET) enables a new kind of 'precision pharmacology', able to address questions central to drug development. Biodistribution studies with drug molecules carrying positron-emitting radioisotopes can test whether a new chemical entity reaches a target tissue compartment (such as the brain) in sufficient amounts to be pharmacologically active. Competition studies, using a radioligand that binds to the target of therapeutic interest with adequate specificity, enable direct assessment of the relationship between drug plasma concentration and target occupancy. Tailored radiotracers can be used to measure relative rates of biological processes, while radioligands specific for tissue markers expected to change with treatment can provide specific pharmacodynamic information. Integrated application of PET and magnetic resonance imaging (MRI) methods allows molecular interactions to be related directly to anatomical or physiological changes in a tissue. Applications of imaging in early drug development can suggest approaches to patient stratification for a personalized medicine able to deliver higher value from a drug after approval. Although imaging experimental medicine adds complexity to early drug development and costs per patient are high, appropriate use can increase returns on R and D investment by improving early decision making to reduce new drug attrition in later stages. We urge that the potential value of a translational molecular imaging strategy be considered routinely and at the earliest stages of new drug development.

To evaluate magnetic resonance (MR) imaging in the planning of radiation therapy for patients with cervical cancer. MR imaging was performed in 15 patients with predominantly advanced cervical carcinomas. Skin markings of the radiation ports were labeled with MR-detectable tubing and beads to assess the adequacy of port placement. Volume and extent of tumor at MR imaging were compared with those at physical and computed tomographic (CT) examinations. Tumor involvement of normal structures (parametrium, vagina, endometrium) was more extensive at MR imaging than at clinical examination in six patients (40%) and at CT in five patients (33%), resulting in modification of the radiation fields in eight patients (53%). Tumor size was larger on MR images than at clinical examination in 11 patients (73%). MR imaging can depict tumor volume and better delineate the extent of involvement than physical and CT examination. This can be useful for placement of radiation ports, especially when small boost fields are used.

Many if not most adnexal masses that are resected for suspicion of malignancy are benign, and the ratio of benign to malignant masses removed increases dramatically if asymptomatic women are screened. More specific diagnostic tests may reduce the rate of unnecessary surgery in these patients. Magnetic resonance (MR) imaging may play a role in evaluating women with problematic ultrasound diagnoses. Conventional and chemical shift MR imaging can allow specific diagnosis of dermoid cysts, pedunculated leiomyomas, ovarian fibromas, most endometriomas, and hydrosalpinx. Gadolinium-enhanced MR imaging allows identification of papillary projections and septa in ovarian neoplasms and differentiation of clot and debris from vascularized tissue. Results of available studies suggest that MR imaging of the female pelvis is cost-effective in selected patients and can be used to obviate surgery in some patients. MR imaging with the use of these techniques may allow more appropriate clinical decisions to be made in selected patients with complex adnexal disease.