Design Consideration and Reconstruction Method for Double-source Double-multislice Spiral CT

To accelerate the scan speed and improve the image quality, a new type of CT configuration, "double-source double-multislice spiral CT" (DSDMS-CT), which is based on two sets of single-source multislice spiral CT was proposed with a special reconstruction algorithm. Simulation results using the fan-beam filtered backprojection algorithm with a special interpolation method were presented for both single-source multislice spiral CT and DSDMS-CT. The results of new CT model show that it scans faster than the traditional spiral CT and has a better slice sensitivity profile (SSP) with larger pitch value.

Multislice spiral CT angiography in evaluation of liver transplantation candidates

BACKGROUND: Orthotopic liver transplantation has be- come the treatment of choice for patients with end-stage liver disease. This study was designed to study whether multislice spiral CT angiography (MSCTA) could be used for preoperative evaluation for orthotopic liver transplanta- tion candidates. METHODS: Eighty consecutive potential candidates for liver transplantation were evaluated with dual-phase three-di- mensional CT angiography (3DCTA). The arterial-phase was used to create vascular maps of the celiac axis (inclu- ding the origin of the hepatic common artery, left gastric artery and splenic artery) and origin of the superior mesen- teric artery. The portal venous-phase was used to analyze portal vein thrombosis and collateral vascularization of the portal vein. Statistical analyses were made using the chi- square test for differences between hepatic arterial anatomy of 80 patients and Michel's anatomy of 200 patients. Appearance of MSCTA and operative results of 16 patients were analyzed. RESULTS; Sixty-two patients (77.5%) showed conven- tional and 18 (22.5%) nonconventional hepatic arterial anatomy. A significant difference was found between the two groups in anatomy of the hepatic artery (P <0.05). Celiac axis stenosis was observed in 6 patients, SA aneu- rysm in 2, small-caliber hepatic arterial vessels in 2, and portal vein thrombosis in 15. Vascular structures of 16 ope- rative patients were well defined. CONCLUSION: As a noninvasive examination, MSCTA can provide a comprehensive preoperative vascular evalua- tion for liver transplantation candidates.

Improved simultaneous multislice magnetic resonance imaging using total variation regularization

Controlled aliasing in parallel imaging results in higher acceleration （CAIPIRINHA） for simultaneous multislice imaging has been proposed recently, which combines multiband excitation and phase cycling techniques to reduce scan time and improve subsequent imaging reconstruction. In this work, the total variation （TV） regularization method is used to further improve CAIPIRINHA. The TV regularization uses an edge-preserving prior, which establishes a relationship between neighboring pixels for image reconstruction. It reduces artifacts and suppresses noise amplification simultaneously. The results are presented with a standard eight-channel head coil with an acceleration factor of 4, where the TV-regularized CAIPIRINHA generates an improved reconstruction as compared with a typical nonregularized CAIPIRINHA.

Comparative Analysis of MRI Diagnosis and Multislice CT in the Diagnosis of Soft Tissue Tumors in Limbs

The purpose of this study was to compare and analyze the diagnostic applications of multisliecs spiral computed tomography(MSCT)and diffusively-weighted magnetic resonance imaging(MRI)in soft tissue tumors of extremities.A total of 104 patients with primary soft tissue tumors of limbs were selected for MSCT and MRI examination.MSCT values of various tumor types were compared during CT examination.In MRI detection,the diffusion sensitivity factor(b)of diffuse-weighted MRI was 0.500 s/mm2 to avoid as much as possible the bleeding,necrosis,scar and calcification heterogeneity components during operation.The maximum interest point was selected to observe the apparent diffusion coefficient(ADC)between benign and malignant tumors and muscle tissue.Results showed that among 104 patients,36 of patients were malignant and 68 of patients were benign.MSCT examination was consistent with pathology in 45 cases and MRI in 87 cases.In addition,the 59 of patients in MSCT examination and the 17 of patients in MRI were qualitative error and uncertainty.Soft tissue tumors on MSCT showed a low-density mass,and lipoma and cyst were specific.In MRI examination,T1WI and T2WI were significantly different in different types of tumors,while ADC values of malignant tumors were significantly lower than those of benign tumors and muscle tissues(P<0.01).However,there was no significant difference in ADC between benign tumor and muscle tissue(P>0.05).Therefore,MSCT can clearly show the soft tissue tumor lesions of the limbs and identify the relationship between them and the surrounding tissues.However,MSCT cannot make accurate characterization.MRI diffusivity weighted imaging can better differentiate benign from malignant and infer the histological origin of lesions.The detection level of MRI was significantly higher than that of CT,which was more consistent with pathology.Therefore,in the preoperative diagnosis of soft tissue tumors in limbs,MRI diffused-weighted imaging should be the first choice.

Myocardial bridging detection by non-invasive multislice spiral computed tomography： comparison with intravascular ultrasound

Background Invasive intravascular ultrasound （IVUS） is current diagnostic standard for myocardial bridging （MB）. Non-invasive multislice computerized tomography coronary angiography （MSCT） technique has provided a good anatomical view of the tunnel artery now. Methods A total of 51 consecutive patients with atypical or typical angina scheduled for IVUS were enrolled in this study and MSCT was performed 7 days before IVUS. Coronary imaging was quantified using IVUS and MSCT. Four main vessels （left main artery （LMA）, left anterior descending （LAD）, left circumflex （LCX）, right coronary artery （RCA）） were examined. Results Forty-one out of 51 （80%） patients received metaprolol （25 mg） before the MSCT scan and 25 of them were current beta-blocker users. The mean heart rate was （64_＋3） beats per minute. A total of 51 patients underwent IVUS examination （30 with MB and 21 without MB） were chosen for this study. Twenty-eight out of 30 MB cases were correctly diagnosed by MSCT and 2 patients with MB were not detected. Comparison with IVUS, the sensitivity of detection by MSCT was 93%, specificity was 100%. The lumen diameter of the tunnel artery derived from MSCT and IVUS significantly decreased from （2.9±0.3） mm to （2.4±0.4） mm （P〈0.001） and from （3.3±0.3） mm to （2.6±0.5） mm （P〈0.001）, respectively. Minimal and maximal diameters of MB derived from MSCT were significantly smaller than those from IVUS （（2.4±0.4） mm vs （2.6±0.5） mm, P〈0.05 and （2.9±0.3） mm vs （3.3±0.3） mm, P〈0.05）, respectively. Conclusions MSCT offers a reliable non-invasive method for MB in LAD and atherosclerosis diagnosis with diagnostic accuracy comparable with invasive IVUS.

Quantitative and qualitative assessment of non-obstructive left main coronary artery plaques using 64-multislice computed tomography compared with intravascular ultrasound

Background There are few reports of quantitative and qualitative measuring of left main coronary artery （LMCA） plaques by multislice computed tomography coronary angiography （MSCTA）, especially when compared with intravascular ultrasound （IVUS） as reference standard. The aim of this study was to evaluate the use of 64-MSCTA in the diagnosis of LMCA disease, and the accuracy of MSCTA in the quantitative and qualitative assessment of the LMCA lesion as compared with IVUS.Methods A total of 91 patients （53 men, 38 women, mean age （64.78±9.19） years） were examined by 64-MSCTA and IVUS. Compared with the IVUS, the sensitivity, specificity, positive and negative predictive values （PPV and NPV） of the MSCTA on the diagnosis of LMCA diseases were calculated. Also, kappa index （K） for the agreement between MSCTA and IVUS was calculated. Minimal lumen area （MLA）, external elastic membrane cross-sectional area （EEM-CSA） and plaque burden were measured by two blinded and independent operators on MSCTA cross-sectional reconstruction and compared with the parameters measured from IVUS by manually tracing. The CT value of soft, fibrous and calcific plaques was measured using IVUS classification of the plaques.Results The sensitivity, specificity, PPV and NPV of MSCTA for detecting LMCA plaques were 93.1%, 84.2%, 95.7%, 76.2%, respectively. Kappa index （K=0.744, P〈0.001） indicated excellent agreement between MSCTA and IVUS. The Pearson index between MLA on IVUS and MLA on MSCTA was 0.815 （P 〈0.01）. The Pearson index of plaque burden and EEM-CSA between IVUS and MSCTA was 0.736 and 0.740 respectively （both P 〈0.01）. The CT value of soft plaque, fibrous plaque and calcific plaque compared with IVUS were （52.52±15.71） HU, （108.32±43.44） HU and （604.16±377.67） HU （P〈0.001）. Receiver operating characteristic curve analysis of CT value of non-calcific plaques for predicting soft plaques showed the cutpoint was 54.35 HU, with a sensitivity of 83.3% and specificity of 94.4%. Conclusions Sixty-four section MSCTA is an effective diagnostic tool for the detection of LMCA plaques with higher sensitivity and specificity. The correlation of quantitative and qualitative analysis between MSCTA and IVUS was excellent. The CT value of plaques can help the diagnosis of plaque composition.

Role of contrast enhanced ultrasound in detection of abdominal aortic abnormalities in comparison with multislice computed tomography

Conventional ultrasound （US） is the most widely used imaging modality in routine clinical practice worldwide. The limitations of conventional ultrasound in the detection of aortic lesions versus multi-slice computed tomography angiography （MS-CTA） are well known.

The accuracy and optimal slice thickness of multislice helical computed tomography for right and left ventricular volume measurement

Background Multislice helical computed tomography (MSCT) has been used to depict coronary anatomy noninvasively, and proved useful for evaluating ventricular function. The aim of our study was to assess the accuracy of ventricular volume as measured by MSCT.Methods Fourteen human left ventricular (LV) and 15 right ventricular (RV) casts were scanned by MSCT. A series of LV and RV short-axis images were reconstructed later with slice thickness of 2.0 mm, 3.5 mm, 5.0 mm, 7.0 mm, and 10.0 mm. Ventricular volume was calculated by the multislice tomographic Simpson’s method. True LV and RV cast volumes were determined by water displacement. Results Both calculated LV and RV volumes correlated highly with the corresponding true volumes (all r>0.95, P<0.01). But with slice thickness from 2.0 mm to 10.0 mm, MSCT scanning overestimated the corresponding true volume by (3.21±5.95) ml to (12.58±8.56) ml for LV and (10.22±8.45) ml to (23.91±12.24) ml for RV (all P<0.01). There was a very high correlation between the overestimation and the selected slice thickness for both LV and RV volume measurements (r=0.998 and 0.996, P<0.01, respectively). However, when slice thickness was reduced to 5.0 mm, the overestimation for both LV and RV volume measurements became nonsignificant for slice thickness from 2.0 mm to 5.0 mm. Conclusions Both LV and RV volumes can be accurately estimated by MSCT. Thinner slice has more accurate calculated volume. However, 5.0 mm slice thickness is thin enough for an accurate measurement of LV or RV volume.

Detection of tracheal branching with computerized tomography:The relationship between the angles and age-gender

BACKGROUND The data obtained on the anatomical knowledge of the tracheobronchial system can be used for diagnosis,treatment and interventional interventions in areas such as anesthesia,thoracic surgery,pulmonary physiology.AIM To determine the tracheobronchial branching angles in pediatric and adult populations by using the multislice computed tomography(CT)and minimum intensity projection(MinIP)technique,which is a non-invasive method.METHODS Our study was carried out retrospectively.Patients who underwent contrast and non-contrast CT examination,whose anatomically and pathophysiologically good tracheobronchial system and lung parenchyma images were obtained,were included in the study.Measurements were made in the coronal plane of the lung parenchyma.In the coronal plane,right main bronchus-left main bronchus angle,right upper lobe bronchus-intermedius bronchus angle,right middle lobe bronchus-right lower lobe bronchus angle,left upper lobe bronchus-left lower lobe bronchus angle were measured.RESULTS The study population consisted of 1511 patients,753 pediatric(mean age:13.4±4.3;range:1-18 years)and 758 adults(mean age:54.3±17.3;range:19-94 years).In our study,tracheal bifurcation angle was found to be 73.3°±13.7°(59.6°-87°)in the whole population.In the pediatric group,the right-left main coronal level was found to be higher in boys compared to girls(74.6°±12.9°vs 71.2°±13.9°,P=0.001).In the adult group,the right-left main coronal level was found to be lower in males compared to females(71.9°±12.9°vs 75.8°±14.7°,P<0.001).CONCLUSIONS Our study,with the number of 1511 patients,is the first study in the literature with the largest number of patient populations including pediatric and adult demographic data,measuring the angle values of the tracheobronchial system using multislice CT and MinIP technique.Study data will not only be a guide during invasive procedures,but it can also guide studies to be done with imaging methods.

Coronary CT angiography:Diagnostic value and clinical challenges

Coronary computed tomography(CT)angiography has been increasingly used in the diagnosis of coronary artery disease due to improved spatial and temporal resolution with high diagnostic value being reported when compared to invasive coronary angiography.Diagnostic performance of coronary CT angiography has been significantly improved with the technological developments in multislice CT scanners from the early generation of 4-slice CT to the latest 320-slice CT scanners.Despite the promising diagnostic value,coronary CT angiography is still limited in some areas,such as inferior temporal resolution,motion-related artifacts and high false positive results due to severe calcification.The aim of this review is to present an overview of the technical developments of multislice CT and diagnostic value of coronary CT angiography in coronary artery disease based on different generations of multislice CT scanners.Prognostic value of coronary CT angiography in coronary artery disease is also discussed,while limitations and challenges of coronary CT angiography are highlighted.

Coronary computed tomography angiography in coronary artery disease

AIM: To investigate the research directions of coronary computed tomography (CT) angiography in the diagnosis of coronary artery disease (CAD) based on a systematic review of the literature.METHODS: A search of articles on coronary CT angiography in the diagnosis of CAD was performed during a 6-year-period between 2005 and 2010 from f ive main radiology journals namely, Radiology, American Journal of Roentgenology, European Radiology, European Journal of Radiology and British Journal of Radiology. Analysis of the references was focused on the research directions of coronary CT angiography with regard to the type of studies in terms of diagnostic value, application of dose-reduction strategies and resultant effective radiation doses with use of these techniques.RESULTS: One hundred and forty two studies were identified which met the selection criteria and were included in the analysis. 64-slice CT (single source anddual-source CT) dominated 78% of the coronary CT angiography studies. Prior to 2007, research was focused on the diagnostic value of coronary CT angiography, but since 2008 more attention has been paid to radiation dose reduction. Radiation dose was reported in 64 studies, representing 45% of total studies published in the f ive radiology journals. Various dose-saving strategies have been implemented and prospective electrocardiography-triggering and high pitch techniques were found to be the most effective approaches for radiation dose reduction, with the corresponding mean effective dose being 3.5 ± 1.9 mSv and 1.7 ± 0.6 mSv, respectively.CONCLUSION: This review shows that the current research in coronary CT angiography has shifted from the previous focus on diagnostic accuracy in CAD to more emphasis on radiation dose reduction.

Role of three-dimensional imaging integration in atrial fibrillation ablation

Atrial fibrillation is the most common arrhythmia and in symptomatic patients with a drug-refractory form,catheter ablation aimed at electrically disconnecting the pulmonary veins(PVs) has proved more effective than use of antiarrhythmic drugs in maintaining sinus rhythm during follow-up.On the other hand,this ablation procedure is complex,requires specific training and adequate clinical experience.A main challenge is represented by the need for accurate sequential positioning of the ablation catheter around each veno-atrial junction to deliver point-by-point radiofrequency energy applications in order to achieve complete and persistent electrical disconnection of the PVs.Imaging integration is a new technology that enables guidance during this procedure by showing a three-dimensional,pre-acquired computed tomography or magnetic resonance image and the relative real-time position of the ablation catheter on the screen of the electroanatomic system.Reports in the literature suggest that imaging integration provides accurate visual information with improvement in the procedure parameters and/or clinical outcomes of the procedure.

From the epicardial adipose tissue to vulnerable coronary plaques

Thin cap fibroatheromas(TCFAs) are thought to be the most common underlying substrate in patients suffering acute coronary thrombotic events.Recently,an interesting association between TCFAs and a particular depot of visceral fat called epicardial adipose tissue(EAT) has been suggested.In this article,we discuss some basic and clinical aspects of this association and then briefly review some of the pathophysiological characteristics attributed to EAT that explain why this particular depot of fat has been attracting the attention of the cardiological scientific community in recent years.Finally we discuss the value of optical coherence tomography in the diagnosis of TCFAs and the role of multislice computed tomography to assess EAT.

Coronary CT angiography:Dose reduction strategies

With the introduction of 64- and post-64 slice computed tomography(CT)technology,coronary CT angiography has been increasingly used as a less invasive modality for the diagnosis of coronary artery disease.Despite its high diagnostic value and promising results compared to invasive coronary angiography,coronary CT angiography is associated with high radiation dose,leading to potential risk of radiation-induced cancer.A variety of dose-reduction strategies have been reported recently to reduce radiation dose with effective outcomes having been achieved.This article presents an overview of the various methods currently used for radiation dose reduction.

Coronary CT angiography:Beyond morphological stenosis analysis

Rapid technological developments in computed tomography(CT)imaging technique have made coronary CT angiography an attractive imaging tool in the detection of coronary artery disease.Despite visualization of excellent anatomical details of the coronary lumen changes,coronary CT angiography does not provide hemodynamic changes caused by presence of plaques.Computational fluid dynamics(CFD)is a widely used method in the mechanical engineering field to solve complex problems through analysing fluid flow,heat transfer and associated phenomena by using computer simulations.In recent years,CFD is increasingly used in biomedical research due to high performance hardware and software.CFD techniques have been used to study cardiovascular hemodynamics through simulation tools to assist in predicting the behaviour of circulatory blood flow inside the human body.Blood flow plays a key role in the localization and progression of coronary artery disease.CFD simulation based on 3D lumina reconstructions can be used to analyse the local flow fields and flow profiling due to changes of vascular geometry,thus,identifying risk factors for development of coronary artery disease.The purpose of this article is to provide an overview of the coronary CT-derived CFD applications in coronary artery disease.

A New Method of 3-Dimensional Localization of Intraocular Foreign Bodies Using CT Imaging:A Role of Optic Nerve

Computed tomography（CT） is considered the most sensitive method for the detection of intraocular foreign bodies（IOFBs）. The purpose of this study was to evaluate a new method of 3-dimentional（3D） localization of IOFBs that takes advantage of the anatomical structure of the optic nerve and to assess the clinical outcomes using this new method. Twenty-two trauma patients with IOFBs or suspected IOFBs admitted to our hospital were scanned with multislice CT（MSCT） between July and December 2003. All scanning was performed with a 16-row spiral CT in axial plane using a sequential scanning protocol. During the scanning, the eyeball of the patient was kept stable and was not allowed to rotate internally or externally. Section collimation was set at 16 mm × 0.75 mm. Table feed was 12 mm. Reconstruction index was 0.75 mm. After scanning, the reconstructed images were loaded into a workstation to create the multiplanar reconstruction images with the aid of the 3D software. We compared the localization results with the operative findings. Multiplanar reconstruction images showed IOFBs in all 22 patients. IOFBs occurred in the eyeball of 14 patients, in the wall of the eyeball of 5 patients and in the posterior orbits of 3 patients. Different surgical procedures were designed according to the localization by this new method and all IOFBs were successfully removed. All of these foreign bodies were metallic and the localization of IOFB using MSCT was consistent with that found by operative findings. It was suggested that MSCT is a simple and effective imaging modality for the localization of IOFBs. In our study, we localized the IOFBs more quickly and accurately by taking advantage of the fixed position of the intraocular segment of the optic nerve, and determined the necessary surgical parameters.

Different therapeutic proportion of patients undergone coronary angiography in the era of development in MSCT

Objective To study the different therapeutic proportion of the patient populations undergone coronary angiography (CAG) in the era of development in multislice spiral computed tomography(MSCT). Methods Two hundred and fifty four consecutive patients(mean age 59.24±10.65) , who underwent CAG at Daxing Hospital from February 2007 through October 2007, were enrolled, 160 patients were male and 94 were female. By evaluating from the coronary angiogram, the patients were not diagnosed to have coronary heart disease(CHD) with less than 50% diameter stenosis of coronary artery; the patients to have CHD with more than or equal to 50% stenosis of coronary artery; the patients were performed the procedure of percutaneous coronary intervention(PCI) with more than or equal to 70% stenosis; the patients were proposed to have coronary aortic bypass graft(CABG) surgery with left main coronary artery lesions or diffuse triple coronary artery lesions. Results In the 254 consecutive patients, 59 patients(23.2%) had not been diagnosed to have CHD; 195(76.8%)to have CHD, of these patients with CHD, 49 patients(19.3%)were not indicated for PCI (including the patients receiving follow-up coronary angiography after stenting), 81(31.9%)had been performed the procedure of stent implantation, 57(22.4%)proposed to have CABG, 8(3.1%)the procedure of PCI had not been successful, or had not been performed because of patients opposing to this therapy. Conclusion Multislice spiral computed tomography can be applied as a non-invasive screening tool to exclude the presence of CHD, to increase the positive proportion of the populations with CHD in all patients receiving coronary angiograhpy, to avoid the use of CAG in a subset of

Practical update on imaging and transcatheter aortic valve implantation

After very rapid advances in the development of the technique and devices,transcatheter aortic valve implantation(named TAVI or TAVR),is today a reality that is here to stay.It has become the minimallyinvasive treatment option for high-risk and non-surgical patients with severe symptomatic aortic stenosis.Requiring the participation of a multidisciplinary team for its implementation,cardiac imaging plays an important role.From pre-assessment to determine the suitability of the patient,the access site,the type of device,to the guidance during the procedure,and ultimately the long term monitoring of the patient.Correct selection of the patient and device,correct placement of the stent-valve and early detection of complications are of paramount importance for procedural success and for patient outcome.Each technique has advantages and disadvantages,being the cardiologist who will determine the best approach according to the type of patient and the expertise of the center in each one of them.This article summarizes the last contributions of the most common used imaging techniques,in each step of the procedure.

Computed Tomography Diagnosis of Acute Appendicitis—Pictorial Essay

Acute appendicitis is a common surgical emergency with varied clinical presentations. Early diagnosis is absolutely necessary to minimize morbidity whereas delayed or missed diagnosis can cause adverse consequences. Computed tomography is a highly accurate imaging technique for diagnosing appendicitis. Hence it plays a valuable role in selected patients with suspected appendicitis;[1]. In this essay, we review the normal Computed tomography anatomy of the appendix and the right lower quadrant and illustrate the Computed tomography signs of appendicitis and important differential diagnostic entities. The Computed tomography appearance of complications of acute appendicitis is also presented, as are issues concerning clinical presentation and duration of the symptoms. Computed tomography signs can be varied and overlooked as they say what is easy to see is also easy to miss.

A pilot study on diagnosis of coronary artery disease using computed tomography first-pass myocardial perfusion imaging at rest

Background:Although computed tomography coronary angiography (CTCA) can identify coronary stenosis,little data exists on the ability of multislice computed tomography (MSCT) to detect myocardial perfusion defects at rest.Methods:In 33 patients with diagnosed or suspected coronary artery disease (CAD),CTCA using retrospective electrocardiography (ECG) gating at rest and invasive coronary angiography (ICA) was performed.The 2D myocardial images were reconstructed in diastolic and systolic phases using the same raw data for CTCA.CT values of the myocardium were used as an estimate of myocardial enhancement,which were shown by color mapping.Myocardial ischemia was defined as a pattern of transient endocardial hypo-enhancement at systole and normal enhancement at diastole.The results of ICA were taken as the reference standard.Results:When a diameter reduction of more than 50% in ICA was used as diagnostic criteria of CAD,the sensitivity,specificity,positive predictive value (PPV),and negative predictive value (NPV) of CT first-pass myocardial perfusion imaging (MPI) at rest were 0.85,0.67,0.92,and 0.50 per patient,respectively,and 0.58,0.93,0.85,and 0.76 per vessel,respectively.Conclusions:CT first-pass MPI at rest could detect CAD patients,which could become a practical and convenient way to detect ischemia,consequently offering the ability for MSCT to act as a "one stop shop" for the diagnosis of CAD.