Imaging Modalities In Terms Research Articles

Comparison between pelvic MRI, CT, and PET/CT in baseline staging and radiation planning of anal squamous cell carcinoma.

To investigate the differences in baseline staging of anal squamous cell carcinoma based on CT, MRI, and PET/CT, and the resultant impact on the radiation plan. This retrospective study included consecutive patients with anal squamous cell carcinoma who underwent baseline pelvic MRI, CT, and PET/CT (all examinations within 3weeks of each other) from January 2010 to April 2020. CTs, MRIs, and PET/CTs were re-interpreted by three separate radiologists. Several imaging features were assessed; tumor stage was determined based on the eight edition of the American Joint Committee on Cancer (AJCC) staging manual; and T (tumor), N (node), and M (metastasis) categories were determined based on National Comprehensive Cancer Network (NCCN) guidelines. Radiologist assessments were then randomly presented to a radiation oncologist who formulated the radiation plan in a blinded fashion. Across 28 patients (median age, 62years [range, 31-78], T-category classification was significantly different on PET/CT compared to MRI and CT (p = 0.037 and 0.031, respectively). PET/CT staged a higher proportion of patients with T1/T2 disease (16/28, 57%) compared to MRI (11/28, 39%) and CT (10/28, 36%). MRI staged a higher proportion of patients with T3/T4 disease (14/28, 50%) compared to CT (12/28, 43%) and PET/CT (11/28, 39%). However, there was no significant difference between the three imaging modalities in terms of either N-category, AJCC staging, or NCCN TNM group classification, or in treatment planning. Our exploratory study showed that MRI demonstrated a higher proportion of T3/T4 tumors, while PET/CT demonstrated more T1/T2 tumors; however, MRI, CT, and PET/CT did not show any significant differences in AJCC and TNM group categories, nor was there any significant difference in treatment doses between them when assessed independently by an experienced radiation oncologist.

Inter-Rater Reliability of Proliferative Diabetic Retinopathy Assessment on Wide-Field OCT-Angiography and Fluorescein Angiography.

To assess inter-rater reliability in the detection of proliferative diabetic retinopathy (PDR) changes using wide-field optical coherence tomography angiography (WF-OCTA) versus fluorescein angiography (FA). This retrospective, cross-sectional study included patients with severe nonproliferative and PDR. Images were acquired with 12 × 12 mm WF-OCTA and FA with a 55° lens. Images were cropped to represent the exact same field of view. Qualitative (detection of neovascularization at the disc [NVD] and elsewhere [NVE], enlarged foveal avascular zone [FAZ], vitreous hemorrhage [VH]) and quantitative analyses (FAZ area, horizontal, vertical, and maximum FAZ diameter) were performed by 2 masked graders using ImageJ. Inter-rater reliability was calculated using unweighted Cohen's kappa coefficient (κ) for qualitative analyses and intraclass correlation coefficients (ICC) for quantitative analyses. Twenty-three eyes of 17 patients were included. Inter-rater reliability was higher for FA than for WF-OCTA in qualitative analyses: κ values were 0.65 and 0.78 for detection of extended FAZ, 0.83 and 1.0 for NVD, 0.78 and 1.0 for NVE, and 0.19 and 1 for VH for WF-OCTA and FA, respectively. In contrast, inter-rater reliability was higher for WF-OCTA than for FA in the quantitative analyses: ICC values were 0.94 and 0.76 for FAZ size, 0.92 and 0.79 for horizontal FAZ diameter, 0.82 and 0.72 for vertical FAZ diameter, and 0.88 and 0.82 for maximum FAZ diameter on WF-OCTA and FA, respectively. Inter-rater reliability of FA is superior to WF-OCTA for qualitative analyses whereas inter-rater reliability of WF-OCTA is superior to FA for quantitative analyses. The study highlights the specific merits of both imaging modalities in terms of reliability. FA should be preferred for qualitative parameters, whereas WF-OCTA should be preferred for quantitative parameters.

Antenatal imaging: A pictorial review.

Today, in parallel with the use of imaging modalities increases in all fields, the use of imaging methods in pregnant women is increasing. Imaging has become an integral component of routine pregnancy follow-up. Imaging provides parents with an early opportunity to learn about the current situation, including prenatal detection of anomalies or diseases, etiology, prognosis, and the availability of prenatal or postnatal treatments. Various imaging modalities, especially ultrasonography, are frequently used for imaging both maternal and fetal imaging. The goal of this review was to address imaging modalities in terms of usefulness and safety, as well as to provide demonstrative examples for disorders. And this review provides current information on selecting a safe imaging modality to evaluate the pregnant and the fetus, the safety of contrast medium use, and summarizes major pathological situations with demonstrative sonographic images to assist radiologists and obstetricians in everyday practice.

Skin line and subcutaneous fat in radiology: Opinion

The aim of this paper is to shed light on a neglected topic in radiology which is imaging the skin and subcutaneous fat. A few studies showed that imaging of skin line and subcutaneous fat have clinical benefits for health, cosmetic reasons, and overall wellbeing. This paper will list many issues that can be diagnosed when evaluating a skin line, fold, and subcutaneous fat on different imaging modalities like; X-ray, ultrasound, CT, MRI, etc. Furthermore, this paper will show a comparison of those imaging modalities in terms of measurement accuracy, diagnosis of skin and subcutaneous fat diseases, comparison of males and females in terms of fat buildup, and so on. According to the available literature, men have more fat than women in the inner deep layer, but women have more body fat than men. Furthermore, as previously hypothesized and proven wrong, recent paper shows that there is no water in the adipose tissue. In addition, a hierarchy in evaluating skin folds and subcutaneous fat by using imaging modalities is seen in the following order from low accuracy to high accuracy; caliper, X-ray, ultrasound, CT, etc.

Understanding the scope of intracardiac echocardiography in catheter ablation of ventricular arrhythmia.

Over the last few decades, catheter ablation has emerged as the first-line treatment for ventricular arrhythmias. However, detailed knowledge of cardiac anatomy during the surgery remains the prerequisite for successful ablation. Intracardiac echocardiography (ICE) is a unique imaging technique, which provides real-time visualization of cardiac structures, and is superior to other imaging modalities in terms of precise display of cardiac tissue characteristics as well as the orientation of anatomical landmarks. This article aimed to introduce the various advantages and limitations of ICE in the ablation of ventricular arrhythmias.

Comparison of Preoperative Imaging Modalities for the Assessment of Malignant Potential of Pancreatic Cystic Lesions: A Network Meta-analysis.

The aims of this study are to compare the performance of various preoperative imaging modalities for assessing the malignant potential of pancreatic cystic lesions (PCLs) through a network meta-analysis (NMA) and to clarify the role of 18 F-FDG PET in the management of patients with PCL. PubMed, EMBASE, and Cochrane Library were searched for the studies evaluating the performance of preoperative imaging modalities for identifying malignant PCLs. The NMA was performed for 4 representative categories of various imaging modalities in terms of diagnostic performance for differentiating malignant from benign PCL and intraductal papillary mucinous neoplasms only as a subgroup analysis. To calculate the probability of each imaging modality being the most effective diagnostic method, the surface under the cumulative ranking curve values were obtained. A total of 1018 patients from 17 direct comparison studies using 2 or more preoperative imaging modalities were included for differentiating malignant from benign PCL. The positive predictive value (PPV) and accuracy of 18 F-FDG PET were significantly higher than that of CT (PPV: odds ratio [OR], 2.66; 95% credible interval [CrI], 1.21-6.17; accuracy: OR, 2.63; 95% CrI, 1.41-5.38) or MRI (PPV: OR, 2.50; 95% CrI, 1.09-6.26; accuracy: OR, 2.50; 95% CrI, 1.28-5.47) in all PCLs, as well as in the subgroup analysis for intraductal papillary mucinous neoplasm only. 18 F-FDG PET showed the highest surface under the cumulative ranking curve values in all diagnostic performance areas of sensitivity, specificity, PPV, negative predictive value, and accuracy, followed by MRI or CT. The results from this NMA suggest that 18 F-FDG PET is the best preoperative imaging modality for differentiating malignant from benign PCLs and that it can be used for the preoperative evaluation of PCLs.

Comparison of susceptibility weighted imaging with conventional MRI sequences in multiple sclerosis plaque assessment: A cross-sectional study.

Background:The current study was performed to compare susceptibility-weighted imaging (SWI) with magnetic resonance imaging (MRI) methods of T2-weighted (T2W) and fluid-attenuated inversion recovery (FLAIR) imaging in multiple sclerosis (MS) plaque assessmentMaterials and Methods:This cross-sectional study was conducted among 50 MS patients referred to Shafa Imaging Center, Isfahan, Iran. Patients who fulfilled McDonald criteria and were diagnosed with MS by a professional neurologist at least 1 year before the study initiation were included in the study. Eligible patients underwent brain scans using SWI, T2W imaging, and FLAIR. Plaques’ number and volume were detected separately for each imaging sequence. Moreover, identified lesions in SWI sequence were evaluated in terms of iron deposition and central veinsResults:Totally 50 patients (10 males and 40 females) with a mean age of 28.48 ± 5.25 years were included in the current study. Majority of patients (60%) had a disease duration of >5 years, and mean expanded disability status score was 2.56 ± 1.32. There was no significant difference between different imaging modalities in terms of plaques’ number and volume (P > 0.05). It was also found that there was a high correlation between SWI and conventional imaging techniques of T2W (r = 0.97, 0.91, P < 0.001) and FLAIR (r = 0.99, 0.99, P < 0.001) in the estimation of both the number and volume of plaques (P < 0.001)Conclusion:The results of the present study indicated that SWI and conventional MRI sequences have similar efficiency for plaque assessment in MS patients.

Comparison of Conventional Xrays with CT Based Approaches for Detection of Lytic Lesions in Multiple Myeloma

Comparison of Conventional Xrays with CT Based Approaches for Detection of Lytic Lesions in Multiple Myeloma

Imaging Features of Vulnerable Carotid Atherosclerotic Plaque and the Associated Clinical Implications

Carotid atherosclerotic plaque composition influences plaque rupture risk and may be used to better stratify patients based on ischemic stroke risk than degree of luminal stenosis alone. The goal of this review is to critically evaluate the ability of both conventional and advanced noninvasive vascular imaging techniques to identify and characterize vulnerable carotid plaques. Advanced noninvasive vascular imaging techniques include contrast-enhanced vascular ultrasound, dual-energy CT, and MR vessel wall imaging (VWI). Each of these modalities has unique strengths with the ability to evaluate the degree of luminal stenosis and provide insight into carotid atherosclerotic plaque composition. MR VWI has proven superior to other imaging modalities in terms of its ability to accurately characterize and quantify components of carotid plaque including intraplaque hemorrhage, lipid-rich necrotic core, dystrophic calcification, and the integrity of the plaque fibrous cap. Advanced noninvasive vascular imaging techniques such as MR VWI offer important insights into carotid atherosclerotic plaque composition and have the potential to dramatically improve the quality of care delivered to patients with carotid atherosclerosis.

Estimation the Doses of Patients Resulting from Diagnostic Cardiac Imaging Modalities

Evaluating the hazards and beneficiary of cardiac imaging for patients is considered of high concern. There is a lack of information about the harm associated with cardiac modalities. Aim: Comparison of different cardiac imaging modalities in terms of patient dose. Method: 120 patients (weight=85 ± 10 Kg and Age=50 ± 10) are divided into three groups according to cardiac diagnostic procedures (A): n=40, SPECT (Siemens Symbia), Injected activity=950 MBq for stress/rest on two days); (B): n=40, Fluoroscopy (Siemens), The fluoroscopy average time and cine-modes was 4.2 ± 1.8 min and 10.7 ± 2.9 min respectively) and (C): n=40, CT Coronary (Philips 256), KV=120, MA=300). Results: CT Coronary (Gp.C) is highly significant patient dose (p<0.005) than SPECT (Gp.A). Where the average effective doses of groups C and A are 32.0 ± 10.5 mSv and 13.5 ± 1.7 mSv respectively. The effective dose of ICA (Gp. B) is 49.1 ± 2.5 mSv which is highly significant (p<0.05) than A and C groups. Conclusion: Our results concluded that there is evidence supportive of high effective dose which reflects an increased risk of cancer incidence at levels of radiation commonly received by cardiac diagnostic imaging modalities.

Effects of Horizontal Beam Angulations and Imaging System on the Identification of the MB2 of Maxillary First Molar: An ROC Analysis

The aim of this study was to evaluate the optimal horizontal beam angulation for the detection of second mesiobuccal canal (MB2) in maxillary first molar using three imaging modalities in terms of receiver operating characteristic (ROC) curve. Micro-computed tomography (micro-CT) was used to validate the presence or absence of MB2 canal. Images were generated with three different imaging modalities (analogue film, Visualix and VistaScan) for the twelve models at 10° intervals between 0。 to 30。 from both right and left sides. Each model consisted of maxillary second premolar, maxillary first and second molar arranged to replicate a posterior dentate maxilla. Images were scored on a 5-point scale by 15 observers. ROC analysis was performed to identify the optimal horizontal angulation for the three imaging modalities and the best observer groups. ANOVA was also used to assess if there was a difference between the three imagining modalities and between the observer groups. ROC analysis demonstrated that the highest area under the curve (AUC) was related to angle +20。 (right). The AUC for the three radiographic techniques at angle +20。 were as followed (analogue film, 0.625; Visualix, 0.544; VistaScan, 0.508). There was a significant difference between the analogue film and the other two digital systems (p<0.05). The +20。 horizontal beam angulation for the analogue film was found to be optimal in the identification of MB2 canal with all imaging modalities. Endodontists demonstrated a significantly better performance compared with the other two groups.

Pretransplant PET Positivity Predicts Early Relapse with Poor Outcome in Patients of Multiple Myeloma Undergoing Autologous Stem Cell Transplantation

Background:Multiple Myeloma is a heterogeneous disease with few patients enjoying overall survival up to a decade while others dying within few years from diagnosis. Multiple staging systems and risk stratification models based on clinical features, laboratory parameters and cytogenetics have been used to predict the response to therapy and outcomes. Positron emission tomography integrated with computerised tomography (PET-CT) offers several advantages as compared to conventional bone imaging modalities in terms of ability to assess extramedulary disease, detection of bone marrow involvement and extent of active disease. Especially important is ability of PET-CT to assess treatment response in terms of FDG activity as bone changes like lytic lesions may persist long on conventional imaging even when disease is in remission. There is scarce data on potential role of PET-CT in response evaluation and prognostication in patients with multiple myeloma. We prospectively analysed the prognostic relevance of PET-CT done prior to autologous stem cell transplant (ASCT).Method:Consecutive patients of multiple myeloma who underwent ASCT between March 2011 and June 2014 were included in this study. All patients received standard novel agent based induction regimen, bortezomib based in 38 patients and lenalidomide based in 5 patients. Patients were evaluated for response by using international myeloma working group (IMWG) criteria after 4-6 cycles of induction regimen. Subsequently patient’s stem cells were harvested from peripheral blood by chemomobilization with cyclophosphamide along with G-CSF. All patients underwent PET-CT immediately pretransplant along with response evaluation by IMWG criteria. PET-CT was considered to be negative if there were no FDG avid lytic lesion and no FDG avid extramedulary disease/soft tissue component was seen. Conditioning regimen used for ASCT were melphalan- 200mg/m2 in 37 patients, reduced doses of melphalan (100-140 mg/m2) in 2 patients or bortezomib- melphalan in 4 patients. Post transplant response evaluation was done at 3 months from transplant and at 3 monthly interval thereafter by SIEP, immunofixation, 24 hours urine BJP, and serum free light chain assay. Probabilities of overall survival and progression free survival were estimated using the Kaplan–Meier method and were compared by log rank test.Results:Forty three patients of multiple myeloma underwent ASCT during the study period. The median age of patients at diagnosis was 49 years and 31 (72 %) were male. As per International Staging System, 15 were stage I, 9 were stage II and 14 were stage III disease at time of diagnosis. After induction therapy, 17 patients achieved CR, 13 patients achieved VGPR, 10 patients had PR while 3 patients had progressive disease (PD) pretransplant. Simultaneously done PET-CT was positive in 15 (34%) patients while it was negative in remaining. At a median follow up of 2.6 years from diagnosis 8 patients had progression of disease and 3 patients have died because of disease progression. So as to evaluate the prognostic utility of PET-CT, patients were grouped into four groups as follows- group 1 - CR/VGPR and PET-CT- negative, group 2 - CR/VGPR and PET-CT- positive, group 3 - PR/PD and PET-CT- negative, group 4 - PR/PD and PET-CT- positive as shown in table 1.Table 1:Pretransplant response according to IMWG criteria and PET-CT.PET negative pretransplantPET positive pretransplantPre transplant CR/VGPR255Pretransplant PR/PD.310At a median follow up of 1.68 years post transplant, 4 patients from group 1 and 4 patients from group 4 have progressed. The estimated probability of overall survival and progression free survival from transplant by Kaplan–Meier method at 3 year is 92 % and 62 % respectively. The time to progression after transplant was significantly short in group 4 as compared to group 1 (median time to progression of 6 months versus 26 months; p=0.001). Out of 8 patients who have relapsed post transplant, 3 patients who were PET-CT positive pretransplant have died while all the 4 patients who were PET negative pretransplant are alive.Conclusion:Pretransplant PET-CT positivity predicts early relapse after ASCT. Survival of such patients is poor after relapse post ASCT. These findings needs validation in larger cohort of patients with longer follow up. DisclosuresNo relevant conflicts of interest to declare.

A comparison of US- versus MR-based 3-D Prostate Shapes Using Radial Basis Function Interpolation and Statistical Shape Models.

This paper presents a comparison of three-dimensional (3-D) segmentations of the prostate, based on two-dimensional (2-D) manually segmented contours, obtained using ultrasound (US) and magnetic resonance (MR) imaging data collected from 40 patients diagnosed with localized prostate cancer and scheduled to receive brachytherapy treatment. The approach we propose here for 3-D prostate segmentation first uses radial basis function interpolation to construct a 3-D point distribution model for each prostate. Next, a modified principal axis transformation is utilized for rigid registration of the US and MR images of the same prostate in preparation for the following shape comparison. Then, statistical shape models are used to capture the segmented 3-D prostate geometries for the subsequent cross-modality comparison. Our study includes not only cross-modality geometric comparisons in terms of prostate volumes and dimensions, but also an investigation of interchangeability of the two imaging modalities in terms of automatic contour segmentation at the pre-implant planning stage of prostate brachytherapy treatment. By developing a new scheme to compare the two imaging modalities in terms of the segmented 3-D shapes, we have taken a first step necessary for building coupled US-MR segmentation strategies for prostate brachytherapy pre-implant planning, which at present is predominantly informed by US images only.

Evaluating the Role of Single-Photon Emission Computed Tomography in the Assessment of Neurotologic Complaints

We conducted a retrospective study to reexamine the value of single-photon emission computed tomography (SPECT) in the evaluation of patients with neurotologic complaints, and to assess the intra- and inter-radiologist variability of SPECT readings. Our study population was made up of 63 patients--23 men and 40 women, aged 34 to 91 years (mean: 59)--who had presented to a tertiary care otolaryngology practice and university hospital for evaluation of head trauma, sensorineural hearing loss, tinnitus, and/or vertigo. All patients had undergone brain scanning with SPECT during their evaluation, and almost all had also undergone magnetic resonance imaging (MRI) and standard computed tomography (CT). We compared the findings of all three imaging modalities in terms of their ability to detect neurotologic abnormalities. We found that detection rates were very similar among the three modalities; abnormalities were found in 24% of SPECT scans, 26% of MRIs, and 23% of CTs. Nevertheless, we did find that among 60 patients who underwent all three types of imaging, 13 (22%) exhibited areas of cerebral hypoperfusion on SPECT while their MRIs and CTs were read as either normal or nonspecific. In all, 18 of these 60 patients (30%) exhibited normal or nonspecific findings on all three types of imaging. In addition, when SPECT scans were read by the same radiologist at different times, different results were reported for 17 of the 63 scans (27%). Likewise, when SPECT scans were read by different radiologists, different results were reported for 21 of 63 scans (33%). We conclude that SPECT may be a valuable complementary diagnostic modality for making a comprehensive neurotologic evaluation and that it may detect abnormalities in some patients whose other imaging is read as normal. However, we did not find that SPECT was the most sensitive of the three modalities in neurotologic evaluation, as we had previously found in a preliminary study that the senior author (R.T.S.) published in 1996. In addition, with respect to our radiologists, both their intra- and inter-reader reliability was low, and we recommend additional study on this matter.

Value of EUS in early detection of pancreatic ductal adenocarcinomas in patients with intraductal papillary mucinous neoplasms

Pancreatic ductal adenocarcinomas (PDAC) sometimes arise in patients with intraductal papillary mucinous neoplasms (IPMNs). This study examined the incidence of PDACs concomitant to or derived from branch duct IPMNs. The usefulness of endoscopic ultrasonography (EUS) relative to other imaging methods for detecting these tumors was also assessed. This retrospective study used data from clinical records and imaging studies that were collected prospectively. During 2001-2009, 167 consecutive patients with IPMNs underwent EUS, ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). The 102 patients whose branch duct IPMNs lacked mural nodules/symptoms and thus did not qualify for resection were followed up by semiannual EUS and annual ultrasonography, CT, and MRI. The sensitivity and specificity with which the four modalities detected IPMN-derived and -concomitant PDACs at the first examination and throughout the study period were evaluated. The rate of PDAC development during follow-up was analyzed by the Kaplan-Meier method. A total of 17 IPMN-derived and 11 IPMN-concomitant PDACs were diagnosed at the first examination. Lesions that did not qualify for resection or chemotherapy were followed up for a median of 42 months. Seven IPMN-concomitant PDACs and no IPMN-derived PDACs were detected during follow-up. The 3- and 5-year rates of IPMN-concomitant PDAC development were 4.0% and 8.8%, respectively. At the first examination, EUS was superior to other imaging modalities in terms of IPMN-derived and -concomitant PDAC detection. Throughout the study period, including follow-up, EUS was significantly better at detecting IPMN-concomitant PDACs than the other modalities. IPMN-concomitant PDACs are quite often found at diagnosis and during follow-up. EUS examination of the whole pancreas plays an important role in the management of IPMNs as it allows the early detection of these small invasive carcinomas.

Ultrasound in the diagnosis of clinical orthopedics: The orthopedic stethoscope

Ultrasonography has advantages over other imaging modalities in terms of availability and comfort, safety, and diagnostic potential. Operating costs are low compared with both computed tomography (CT) and magnetic resonance imaging (MRI). The portable equipment is accessible at locations distant from medical centers. Importantly, ultrasonography is performed while patients lie in a comfortable position, without pain or claustrophobia.

Intravascular Functional Maps of Common Neurovascular Lesions Derived From Volumetric 4D CT Data

Current computed tomography angiography (CTA) postprocessing tools do not support quantitative assessment of intravascular physiology. Dynamic volumetric CT, acquired at a sufficiently high temporal resolution, is ideal for such analysis. Following preliminary experiments in flow phantoms, we examine the segmentation of blood vessels from 4D CT angiography by curve fit and encoding of functional blood flow information into the resulting functional intravascular maps. Flow phantoms were constructed consisting of a single pipe input and 4 simultaneous outputs of varying flow rates. Two outflow pipe diameters were tested. Bolus transit time (TT), time to peak (TTP), and time of arrival (TOA) were analyzed using contrast bolus profiles generated from 4D volumetric CT examinations on a 320 detector scanner in regions of interest placed 10 cm apart in all outflow pipes. Six subjects with various neurovascular lesions were next examined using a volumetric contrast-enhanced 4D CT angiography protocol. Segmentation was performed by quadratic curve fit after comparative analysis and optimization of the segmentation technique using quadratic curves, the gamma variate function, and a simplified formulation of the gamma variate function. After segmentation, quantitative analysis of spatially congruent intravascular voxels including TTP, rise, TT, and slope of the contrast upstroke was employed to encode physiologic information into the segmentations and produce intravascular functional maps. Comparison was made in each case to the patient's routine imaging. Increasing volumetric flow rates correspond to reduction of bolus TT in flow phantoms. TT elongation was observed as the contrast bolus moved distally in all pipes, with greater elongation seen at slower flow rates and larger pipe diameters. A greater difference was observed between TTP proximally and distally in pipes compared with TOA, an effect most prominent at slower flow rates and larger pipe lumens, and thus TTP was chosen for functional encoding into segmentations of the clinical series. In vivo, the quadratic function demonstrated the lowest coefficient of variation when fit to intravascular time density series and outperformed 2 formulations of the gamma variate function. After segmentation with quadratic curves, Gaussian distributions were chosen over gamma variate functions to characterize contrast bolus profiles while neglecting recirculation and to calculate functional parameters for spatial encoding. Intravascular functional maps free of bone artifacts were created in every case that demonstrated all appropriate vessels and showed agreement with conventional imaging modalities in terms of vessel delineation and the diagnosis of vascular pathology. The most useful and interesting functional maps are discussed in each case. The above approach to quantitative CT angiography provides a method of evaluating dynamic CTA data by means of intravascular functional maps. The techniques are broadly applicable in the clinical assessment of a variety of vascular diseases.

Imaging of the pulmonary arteries

For decades, classical pulmonary digital subtraction angiography (DSA) has served as the gold standard for the direct assessment of the pulmonary vasculature. During the past decade, substantial advances have been achieved in all cross-sectional imaging modalities in terms of spatial and temporal resolution. As a consequence of that, computed tomography angiography (CTA) and magnetic resonance imaging (MRI) are the modalities of choice for the morphological (CTA) and functional (MRI) assessment and will be presented in the context of the technical developments (CT: from single-slice scanners to modern multi-slice equipment, including latest innovations such as 320-slice CT and flash technology; MR: 1.5T vs. 3.0T, parallel imaging, time-resolved MR angiographic secquences, as well as perfusion MR imaging). Dedicated contrast media delivery protocols are a prerequisite for optimal results.

Variations in the referral patterns to stress nuclear imaging and stress echocardiography scans

BackgroundStress myocardial perfusion imaging (MPI) and stress echocardiography (Echo) are commonly used for the noninvasive evaluation of patients with suspected coronary artery disease (CAD). Very few studies have compared the referral patterns to these imaging modalities in terms of the clinical profile of patients, reasons for referral, and type of referring physicians. Methods and ResultsThis was a prospective study of 1,020 consecutive patients who were referred for stress MPI (429 patients) or stress Echo (591 patients) at the American University of Beirut Medical Center in the year of 2008. Patients referred to MPI were older and had a higher prevalence of diabetes, hypertension, hypercholesterolemia, smoking, and previous myocardial infarction, coronary angioplasty, or bypass surgery. There were more abnormal scans in the stress MPI group (24% vs 15%, P < 0.001), as well as a higher prevalence of ischemia (15% vs 7.6%, P < 0.001) and impaired left ventricular function with an ejection fraction <50% (11% vs 1.7%, P < 0.001). A higher percentage of stress Echo studies were self-referred by physicians who themselves interpret the scans (31% vs 19%, P < 0.001). ConclusionPatients referred for stress MPI are at a higher risk than those referred for stress Echo having more CAD risk factors, more prior history of coronary events, and an older age. These findings have important implications in the interpretation of studies that compare the diagnostic and prognostic power of these two imaging modalities.

Preliminary evaluation of optical CT scanning versus MRI for nPAG gel dosimetry: The Ghent experience

The aim of this study was to evaluate fast laser-scanning optical CT versus MRI for an nPAG gel dosimeter in terms of accuracy and precision. Three small cylindrical volumetric gel phantoms were fabricated and irradiated with photon beams. The gel dosimeters were scanned with an MR scanner and an in house developed laser scanning optical CT scanner. A comparison between MRI and optical CT scanning was performed based on the reconstructed images.Preliminary results show a fair correspondence in the MRI acquired and optical CT acquired dose maps. Still, ringing artifacts contaminate the reconstructed optical CT images. These may be related to sub-pixel misalignments between the blank projection and the acquired transmission projection of the gel phantom. Another artifact may be caused by refraction near the edges of the field. Further optimisation of our optical CT scanner is required to obtain the same accuracy as with MRI. To make a comparison between the two imaging modalities in terms of precision, the intrinsic dose precision on readout (IPD) was calculated which is independent of spatial resolution and acquisition time. It is shown that optical CT has a better intrinsic dose precision.