Implementation of GPU accelerated SPECT reconstruction with Monte Carlo-based scatter correction

Abstract

Objective

Statistical SPECT reconstruction can be very time-consuming especially when compensations for collimator and detector response, attenuation, and scatter are included in the reconstruction. This work proposes an accelerated SPECT reconstruction algorithm based on graphics processing unit (GPU) processing.

Methods

Ordered subset expectation maximization (OSEM) algorithm with CT-based attenuation modelling, depth-dependent Gaussian convolution-based collimator-detector response modelling, and Monte Carlo-based scatter compensation was implemented using OpenCL. The OpenCL implementation was compared against the existing multi-threaded OSEM implementation running on a central processing unit (CPU) in terms of scatter-to-primary ratios, standardized uptake values (SUVs), and processing speed using mathematical phantoms and clinical multi-bed bone SPECT/CT studies.

Results

The difference in scatter-to-primary ratios, visual appearance, and SUVs between GPU and CPU implementations was minor. On the other hand, at its best, the GPU implementation was noticed to be 24 times faster than the multi-threaded CPU version on a normal 128 × 128 matrix size 3 bed bone SPECT/CT data set when compensations for collimator and detector response, attenuation, and scatter were included.

Conclusions

GPU SPECT reconstructions show great promise as an every day clinical reconstruction tool.

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Evaluation of condyle position in patients with Angle Class I, II, and III malocclusion using cone-beam computed tomography panoramic reconstructions

Abstract

Objectives

This study was performed to compare the positions of the right and left condyles between male and female patients with different Angle malocclusions using cone-beam computed tomography (CBCT) panoramic reconstructions.

Methods

The CBCT images of 60 patients (age of 18–37 years) were retrospectively evaluated. The patients were divided according to their Angle malocclusion classifications (Angle Classes I, II, and III). The condyle-to-eminence, condyle-to-fossa, and condyle-to-meatus distances were measured digitally using i-CAT software.

Results

The left and right condyle-to-fossa distances were the most variable parameters among the Angle classes. The right condyle-to-eminence and right condyle-to-fossa distances were significantly different among the classes. Male patients seemed to have a greater condyle-to-fossa distance on the right side in both the Class I and III groups. The mean distance from the condyle to eminence, condyle to fossa, and condyle to meatus on the right side was the greatest in the Angle Class II group.

Conclusions

In all three types of malocclusion (Angle Classes I, II, and III), the condyles on both the right and left sides were not exactly symmetric or centrally located within the glenoid fossa. This work emphasizes the differences in the condyle position between male and female patients. Furthermore, the symmetry and centricity of the condyles are not dependent on the patient's sex or type of malocclusion.

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Endovascular trans-jugular occlusion of congenital intrahepatic porto systemic venous shunt using simultaneous fluoroscopy and trans-abdominal ultrasound guidance: Report of two cases

Publication date: Available online 20 March 2018
Source:Current Problems in Diagnostic Radiology
Author(s): Ujjwal Gorsi, Naveen Kalra, Pankaj Gupta, Karthik Rayasam, Babu Ram Thapa, Hemant Bhagat, Niranjan Khandelwal
Congenital intrahepatic portosystemic venous shunts (CIPVS) are rare anomalies that can be detected before birth or in early infancy or later in life. Symptomatic shunts are treated as they carry high risk of complications like hepatic encephalopathy. Various treatment options include surgery, endovascular embolization and percutaneous closure devices. We treated two infants with CIPVS successfully by endovascular embolization of the shunt using vascular plug through transjugular route. Trans-abdominal ultrasound guidance in addition to fluoroscopy was used at the time of vascular plug placement. We emphasize that the use of transabdominal ultrasound during endovascular occlusion enhances the safety and technical success rate.



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Factors Influencing Choice of Radiology and Relationship to Resident Job Satisfaction

Publication date: Available online 20 March 2018
Source:Current Problems in Diagnostic Radiology
Author(s): Shanna A. Matalon, Jeffrey P. Guenette, Stacy E. Smith, Jennifer W. Uyeda, Alicia S. Chua, Glenn C. Gaviola, Sara M. Durfee




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Angiomyolipoma of the Kidneys: Current Perspectives and Challenges in Diagnostic Imaging and Image-Guided Therapy

Publication date: Available online 20 March 2018
Source:Current Problems in Diagnostic Radiology
Author(s): Abdul Razik, Chandan J. Das, Sanjay Sharma
Angiomyolipomas (AML) are benign tumors of the kidneys frequently encountered in radiologic practice in large tertiary centers. In comparison to renal cell carcinomas (RCC), AML are seldom treated unless they are large, undergo malignant transformation or develop complications like acute hemorrhage. The common garden triphasic (classic) AML is an easy diagnosis, however some variants lack macroscopic fat in which case the radiologic differentiation from RCC becomes challenging. Several imaging features, both qualitative and quantitative, have been described in differentiating the two entities. Although minimal fat AML is not entirely a radiologic diagnosis, the suspicion raised on imaging necessitates sampling and potentially avoids an unwanted surgery. Recently a new variant, epitheloid AML has been described which often has atypical imaging features and is at a higher risk for malignant transformation. Apart from the diagnosis, the radiologist also needs to convey information regarding nephrometric scores which help in surgical decision making. Recently, more and more AMLs are managed with selective arterial embolization and percutaneous ablation, both of which lack the amount of morbidity associated with surgery. The purpose of this article is to review the imaging and pathologic features of classic AML as well as the differentiation of minimal fat AML from RCC. In addition, an overview of nephrometric scoring and image-guided interventions is also provided.



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Top 100 Cited articles on Radiation Exposure in Medical Imaging: A Bibliometric Analysis

Publication date: Available online 20 March 2018
Source:Current Problems in Diagnostic Radiology
Author(s): Jason Kinnin, Tarek N. Hanna, Marc Jutras, Babar Hasan, Rick Bhatia, Faisal Khosa
BackgroundBibliometric analyses by highest number of citations can help researchers and funding agencies in determining the most influential articles in a field. The main objective of this analysis was to identify the top 100 cited articles addressing radiation exposure from medical imaging and assess their characteristics.MethodsRelevant articles were extracted from the Scopus database after a systematic search by researchers using an iteratively defined Boolean search string. Subsequently, exclusion criteria were applied. A list of top 100 articles was prepared, and articles were ranked according to the citations they had received. No time restriction was applied. Descriptive statistics of the data were compiled.ResultsThe top-cited articles were published from 1970–2013, with the most articles published in 2009 and 2010 (12 articles in each year). The citations ranged from 107–1888 with a median of 272. Manuscripts from our top-cited list originated from 20 different countries, with contributions made by 158 authors and 160 organizations. Eighty-eight percent of studies evaluated patient-related radiation exposure, 7% health care workers, and 5% both or were not specified. Thirty-two percent of studies examined adult populations, 14% pediatric, and 54% included both populations or did not specify. Seventy-two percent of studies were dedicated to Computed Tomography, 8% to radiography/fluoroscopy, 9% to interventional procedures, 4% to nuclear medicine, and 7% to a combination of two or more modalities.ConclusionThe top 100 cited articles in medical imaging related to radiation exposure are diverse, originating from many countries with numerous contributing authors. The most common topics covered involve CT and adult patients. The recent peak in the most-highly cited articles (2010) suggests increased attention has been devoted to this field in recent years. Based on these results, it would appear research on radiation exposure in medical imaging is poised to continue expanding.



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Interventional Radiology-Operated Endoscopy as an Adjunct to Image-Guided Interventions

Publication date: Available online 20 March 2018
Source:Current Problems in Diagnostic Radiology
Author(s): Rajiv N. Srinivasa, Jeffrey Forris Beecham Chick, Kyle Cooper, Ravi N. Srinivasa
Interventional radiology-operated endoscopy is an underutilized technique which may have a significant impact on the ability to treat patients with a variety of conditions. Interventional radiologists are in a unique position to implement endoscopy into routine practice given the manual dexterity and hand-eye coordination already required to perform other image-guided interventions. When used in combination, endoscopy adds an entirely new dimension to the fluoroscopic-guided procedures of which interventional radiologists are accustomed. A number of new and innovative interventions may be performed in the biliary, genitourinary, and gastrointestinal systems through percutaneous access that interventional radiologists already create. Although other specialists traditionally have performed endoscopic interventions and local politics often dictate referral patterns, a collaborative relationship amongst these specialists and interventional radiology will allow for improved patient care. A concerted effort is needed by interventional radiologists to learn the techniques and equipment required in order to successfully incorporate endoscopy into practice. The article presents the setup, equipment, and potential clinical uses of interventional radiology-operated endoscopy.



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