Multidetector Row Research Articles

Role of multidetector computed tomography (MDCT) in diagnosis of secondary intussusception in children

IntroductionIntussusception occurs when a segment of bowel, the intussusceptum, prolapses and invaginates into another segment, the intussuscipiens. It is the most common cause of acute bowel obstruction in infants. Over 90% of childhood intussusceptions are idiopathic, perhaps related to relative hyperplasia of lymphoid follicles in the distal ileum. Underlying pathologic lead points are uncommon. Lymphoma, polyps, Meckel’s diverticulum and hematoma are most common identified lead points in children. Aim of the workTo assess the role of multidetector computed tomographic imaging in the diagnosis of secondary intussusception with pathological leading points in children. Materials and methodsThis study is a retrospective study including 12 children referred to the radiodiagnosis department at Alexandria University Hospitals presenting with signs of acute abdomen, in the period between June 2012 and January 2013, all of which were radiologically diagnosed by computed tomographic imaging as secondary intussusception with pathological leading points which were confirmed by surgery. All the studied patients were subjected to full history taking, thorough clinical examination, laboratory investigations and CT of the abdomen and pelvis: using multidetector row CT. ResultsAll the patients were radiologically diagnosed by computed tomographic imaging as secondary intussusception with pathological leading points which were confirmed by surgery. The associated leading points detected in our cases were reactive mesenteric lymph nodes in three patients, lymphoma in four cases, one post appendectomy case, mesenteric lymphangioma in one case, malrotation in one case and Meckel’s diverticulum in another one case. Intramural hematoma was detected in one case diagnosed as Henoch–Schönlein purpura (8.33%). ConclusionsFinally we conclude that multidetector CT could efficiently diagnose children presenting with secondary intussusceptions.

Paramuscular Perforators in DIEAP Flap for Breast Reconstruction

One of the main steps in perforator flap surgery is to identify the dominant perforator. Using multidetector row computed tomography (MDCT) for the preoperative planning of deep inferior epigastric artery perforator (DIEAP) flap surgery, we identified a perforator with a large caliber, an excellent location in the middle abdominal region, and a totally extramuscular trajectory in a significant number of patients. We describe the frequency of this perforator and determine its characteristics. We conducted a retrospective study of 482 patients who underwent 526 DIEAP flaps for breast reconstruction from October 2003 to October 2011. Mean age at surgery was 51.3 years old. A preoperative MDCT of abdominal vascularization was performed in all patients. MDCT identified a dominant perforator with a paramuscular course in 12.4% of abdominal walls. In all cases, it was located in the midline and emerged directly from the deep inferior epigastric system. Its mean caliber was 1.9 mm. The flap was harvested based on this perforator in all these patients, and mean harvest time was 51 minutes. The characteristics of this perforator made dissection easier and reduced morbidity at the donor site. There were no flap losses and the only complications were minor. We located a paramuscular perforator in 12.4% of patients undergoing breast reconstruction with abdominal perforator flaps. Its morphological features and extramuscular course make it the perforator of choice in DIEAP flap surgery.

Pancreaticobiliary maljunction and biliary cancer.

Pancreaticobiliary maljunction (PBM) is a congenital malformation in which the pancreatic and bile ducts join anatomically outside the duodenal wall. Japanese clinical practice guidelines on how to deal with PBM were made in 2012, representing a world first. According to the 2013 revision to the diagnostic criteria for PBM, in addition to direct cholangiography, diagnosis can be made by magnetic resonance cholangiopancreatography (MRCP), 3-dimensional drip infusion cholangiography computed tomography, endoscopic ultrasonography (US), or multiplanar reconstruction images by multidetector row computed tomography. In PBM, the common channel is so long that sphincter action does not affect the pancreaticobiliary junction, and pancreatic juice frequently refluxes into the biliary tract. Persistence of refluxed pancreatic juice injures epithelium of the biliary tract and promotes cancer development, resulting in higher rates of carcinogenesis in the biliary tract. In a nationwide survey, biliary cancer was detected in 21.6% of adult patients with congenital biliary dilatation (bile duct cancer, 32.1% vs. gallbladder cancer, 62.3%) and in 42.4% of PBM patients without biliary dilatation (bile duct cancer, 7.3% vs. gallbladder cancer, 88.1%). Pathophysiological conditions due to pancreatobiliary reflux occur in patients with high confluence of pancreaticobiliary ducts, a common channel ≥6 mm long, and occlusion of communication during contraction of the sphincter. Once the diagnosis of PBM is established, immediate prophylactic surgery is recommended. However, the surgical strategy for PBM without biliary dilatation remains controversial. To detect PBM without biliary dilatation early, MRCP is recommended for patients showing gallbladder wall thickening on screening US under suspicion of PBM.

Position of Edwards SAPIEN transcatheter valve in the aortic root in relation with the coronary ostia: implications for percutaneous coronary interventions.

To determine the implications of stable coverage of the coronary ostia by the Edwards SAPIEN valve frame in terms of myocardial ischemia and subsequent percutaneous coronary intervention (PCI), following transcatheter aortic valve implantation (TAVI). Edwards SAPIEN frame is frequently deployed relatively higher than recommended and may overlap the coronary ostia. A total of 142 patients (age 81 ± 7 years, male 49%) treated with Edwards SAPIEN valve and with multi-detector row computed tomography at 1 month follow-up were evaluated. The position of the frame in relation to the coronary ostia was assessed. Levels of troponin T were measured 12-24 hr after TAVI. PCI events at follow-up were recorded. The left coronary ostium was fully covered in three (2.1%) patients and the right coronary ostium in 11 (7.7%). There were no differences in troponin T levels between patients with fully covered ostia versus patients with partly or non-covered ostia (0.24 (0.13-0.50) μg/L versus 0.35 (0.15-0.55) μg/L, respectively; P = 0.377). At 30 ± 15 months follow up, 10 (7%) patients underwent successful PCI. Rate of subsequent PCI was similar between patients with any covered ostium and patients with non-covered ostia [4 (7.8%) vs. 6 (6.5%), P = 0.780, respectively]. Full overlap of the coronary ostia by Edwards SAPIEN frame is infrequent and in most cases does not limit subsequent PCI.

Evaluation of Bone Volume after Secondary Bone Grafting in Unilateral Alveolar Cleft Using Computer-Aided Engineering

The purpose of this study was to evaluate the initial defect and the outcome of bone grafts for unilateral alveolar cleft. To determine the absorption of the bone graft in patients with unilateral cleft, computer-aided engineering (CAE) with multi-detector row computed tomography (MDCT) was used. MDCT scans of 29 patients were taken immediately preoperatively and at 1 month and 6 months postoperatively. The patients underwent bone grafting between 8 and 14 years of age using iliac crest bone grafts. Three-dimensional models were created in each period, and the defect at the alveolar cleft and volume of the bone graft were determined in each patient using CAE. Cleft volume and success of alveolar bone grafting were significantly correlated (P < .01). Alveolar clefts with cleft palate required more bone volume than those without cleft palate (P < .01), but the resorption rate did not significantly differ between alveolar clefts with and without cleft palate (0.48 ± 0.14 and 0.49 ± 0.18, respectively; P = .93). In conclusion, three-dimensional reconstruction of bone grafts using CAE based on MDCT provides a valuable objective assessment of graft volume.

Validation of a Monte Carlo model used for simulating tube current modulation in computed tomography over a wide range of phantom conditions/challenges.

Monte Carlo (MC) simulation methods have been widely used in patient dosimetry in computed tomography (CT), including estimating patient organ doses. However, most simulation methods have undergone a limited set of validations, often using homogeneous phantoms with simple geometries. As clinical scanning has become more complex and the use of tube current modulation (TCM) has become pervasive in the clinic, MC simulations should include these techniques in their methodologies and therefore should also be validated using a variety of phantoms with different shapes and material compositions to result in a variety of differently modulated tube current profiles. The purpose of this work is to perform the measurements and simulations to validate a Monte Carlo model under a variety of test conditions where fixed tube current (FTC) and TCM were used. A previously developed MC model for estimating dose from CT scans that models TCM, built using the platform of mcnpx, was used for CT dose quantification. In order to validate the suitability of this model to accurately simulate patient dose from FTC and TCM CT scan, measurements and simulations were compared over a wide range of conditions. Phantoms used for testing range from simple geometries with homogeneous composition (16 and 32 cm computed tomography dose index phantoms) to more complex phantoms including a rectangular homogeneous water equivalent phantom, an elliptical shaped phantom with three sections (where each section was a homogeneous, but different material), and a heterogeneous, complex geometry anthropomorphic phantom. Each phantom requires varying levels of x-, y- and z-modulation. Each phantom was scanned on a multidetector row CT (Sensation 64) scanner under the conditions of both FTC and TCM. Dose measurements were made at various surface and depth positions within each phantom. Simulations using each phantom were performed for FTC, detailed x-y-z TCM, and z-axis-only TCM to obtain dose estimates. This allowed direct comparisons between measured and simulated dose values under each condition of phantom, location, and scan to be made. For FTC scans, the percent root mean square (RMS) difference between measurements and simulations was within 5% across all phantoms. For TCM scans, the percent RMS of the difference between measured and simulated values when using detailed TCM and z-axis-only TCM simulations was 4.5% and 13.2%, respectively. For the anthropomorphic phantom, the difference between TCM measurements and detailed TCM and z-axis-only TCM simulations was 1.2% and 8.9%, respectively. For FTC measurements and simulations, the percent RMS of the difference was 5.0%. This work demonstrated that the Monte Carlo model developed provided good agreement between measured and simulated values under both simple and complex geometries including an anthropomorphic phantom. This work also showed the increased dose differences for z-axis-only TCM simulations, where considerable modulation in the x-y plane was present due to the shape of the rectangular water phantom. Results from this investigation highlight details that need to be included in Monte Carlo simulations of TCM CT scans in order to yield accurate, clinically viable assessments of patient dosimetry.

Fluctuant tonus of the coronary arteries possibly documented by repeated multidetector row computed tomography

Fluctuant tonus of the coronary arteries possibly documented by repeated multidetector row computed tomography

Applied Imagistics of Ischaemic Heart a Survey. From the Epidemiology of Stable Angina In Order to Better Prevent Sudden Cardiac Death

Abstract Coronary computed tomography angiography (CCTA) allows coronary artery visualization and the detection of coronary stenoses. In addition; it has been suggested as a novel, noninvasive modality for coronary atherosclerotic plaque detection, characterization, and quantification. Accurate identification of coronary plaques is challenging, especially for the noncalcified plaques, due to many factors such as the small size of coronary arteries, reconstruction artifacts caused by irregular heartbeats, beam hardening, and partial volume averaging. The development of 16, 32, 64 and the latest 320 row multidetector CT not only increases the spatial and the temporal resolution significantly, but also increases the number of images to be interpreted by radiologists substantially. Radiologists have to visually examine each coronary artery for suspicious stenosis using visualization tools such as multiplanar reformatting (MPR) and curved planar reformatting (CPR) provided by the review workstation in clinical practice

Approach to the management of incidental venous thromboembolic events in patients with cancer.

Venous thromboembolism (VTE) is a frequent clinical complication of cancer and its treatment. Although much of the epidemiologic data regarding this complication have been based on symptomatic events, the use of multidetector row CT scanner technology has led to increased identification of VTE on scans ordered primarily for staging or restaging of malignancy. These incidentally discovered VTEs are variously referred to in the literature as incidental, asymptomatic, unexpected, or unsuspected VTE. A recent guidance paper by the Hemostasis and Malignancy Subcommittee of the International Society on Thrombosis and Haemostasis provided recommendations regarding this terminology (now termed incidental) and reporting of incidental VTE for clinical trials. A growing number of retrospective and case-controlled reports have described the prevalence, prognostic implications, and treatment options for these incidentally discovered VTE events, and have reported similar clinical outcomes for patients with incidental and symptomatic VTE. Because most reported patients with incidental VTE have been treated in a manner similar to those with symptomatic events, the present recommendations, except in rare circumstances, support the use of standard anticoagulation in the management of incidental deep vein thrombosis and pulmonary embolism.

Impaired visibility of the hepatic veins on the multi-detector computed tomography in patients with cirrhosis.

To determine the prevalence and associations of the impaired visibility of the hepatic veins (HV) on the multi-detector row computed tomography (MDCT) in cirrhotic patients. Eighty-seven consecutive cirrhotic patients undergoing triphasic liver MDCT were enrolled. The patency of the HV and the direction of the blood flow in the main portal vein, inhomogeneity of the liver, portal vein thrombosis (PVT), a spontaneous splenorenal shunt, splenic indexes (cm(3)), contour abnormalities, and enlargement of the fissure were evaluated. The prevalence of the impaired visibility of the HV was 38% in the patients with cirrhosis. No significant associations exist between the impaired visibility of the HV and age (p=0.96), sex (p=0.14), portal vein thrombosis (p=0.29), or splenic indexes (p=0.32). Inhomogeneity of the liver (p=0.0001), marked contour abnormalities, (p=0.0001), splenorenal shunt (p=0.02), enlargement of fissure (p=0.0001), and hepatofugal flow (p=0.01) were significantly associated with the impaired visibility of the HV. Inhomogeneity of the liver, marked contour abnormalities, and hepatofugal flow are independently associated with the impaired visibility of the HV in cirrhotic patients on hepatic venous phase CT.

Role and Effectiveness of Percutaneous Arterial Embolization in Hemodynamically Unstable Patients with Ruptured Splanchnic Artery Pseudoaneurysms

To assess the role and effectiveness of percutaneous arterial embolization (TAE) in patients with hemodynamic instability due to hypovolemic shock secondary to ruptured splanchnic artery pseudoaneurysms (SAPA). Seventeen patients (11 men, 6 women; mean age, 53 years) with hemodynamic instability (systolic blood pressure <90 mmHg) due to hypovolemic shock secondary to ruptured SAPA were treated by TAE. Clinical files, multidetector row computed tomography angiography, and angiographic examinations along with procedure details were reviewed. Seventeen SAPAs were present, predominantly located on gastroduodenal or pancreatic arteries (9/17; 53%). Angiography showed extravasation of contrast medium from SAPA in 15/17 patients (88%). Technical success rate of TAE was 100%. TAE was performed using metallic coils in all patients (100%), in association with gelatin sponge in 5/17 patients (29%). TAE allowed controlling the bleeding and returning to normal hemodynamic status in 16/17 patients (94%). In 1/17 patient (6%), surgery was needed to definitively control the bleeding. The mortality and morbidity rate of TAE at 30 days were 0 and 12%, respectively. Morbidity consisted in coil migration in 1/17 patient (6%) and transient serum liver enzyme elevation in 1/17 patient (6%). TAE is an effective and safe treatment option for ruptured SAPA in hemodynamically unstable patients, with a success rate of 94%. Our results suggest that TAE should be the favored option in patients with hemodynamic instability due to ruptured SAPA.

In vivo microstructural analysis of the humeral greater tuberosity in patients with rotator cuff tears using multidetector row computed tomography.

BackgroundIn arthroscopic surgery, the suture anchor technique has become popular for rotator cuff repair. Preoperative evaluation of the bone microstructure is of utmost importance because, especially in elderly patients, osteoporotic changes may cause anchor pullout, which results in failure of rotator cuff repair. Many groups have reported humeral microstructural analysis; however, most studies were experiments using porcine specimens or human cadavers. In this study, we used multidetector row computed tomography to successfully perform in vivo evaluation of the bone microstructure of the humeral greater tuberosity in patients with rotator cuff tears.MethodsTen patients were examined. Regions of interest were defined in six quadrants of the greater tuberosity (medial, lateral, and far lateral rows of the anterior and posterior areas). The local bone mineral density and the trabecular microstructural parameters, including the mean bone volume to total volume (BV/TV), trabecular thickness, trabecular separation, and structure model index (SMI), were measured using bone analysis software.ResultsThe BV/TV of the posteromedial region was highest and the SMI of the posteromedial region was lowest. These findings suggest that the bone quality of the posteromedial portion is the highest within the greater tuberosity.ConclusionBecause the bone quality may be correlated with the pullout strength of suture anchors, our method can help to understand the individual and regional variance in bone quality and may lead to the creation of personalized surgical protocols.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2474-15-351) contains supplementary material, which is available to authorized users.

Tomografía computarizada de pitch alto en estudios de triple descarte: dosis de radiación y calidad de la imagen comparada con la de la tomografía computarizada multidetector

ObjectiveTo compare the image quality and radiation dose from high pitch dual source CT (128-DSCT) versus those from retrospective acquisition with 64-row multidetector CT (64-MDCT) in triple rule-out studies. Material and methodsWe retrospectively studied 60 patients with acute chest pain: 30 with a retrospective EKG acquisition with 64-MDCT and 30 with high pitch 128-DSCT. We quantitatively analyzed the image quality by calculating the vascular density, muscular density (DM), noise, vascular density/noise ratio (VDNR), and contrast/noise ratio (CNR). We qualitatively evaluated the artifacts in the vena cava, aorta, and coronary arteries. We estimated the effective dose (ED) of radiation by means of the dose-length product. ResultsThere were no significant differences between 128-DSCT and 64-MDCT in the vascular density. The VDNR and CNR were higher on 128-DSCT than on 64-MDCT in the aorta (VDNR: 28.9±11.7 vs. 20±5.5; CNR: 24.4±10.9 vs. 16.8±5.4; P<.01), in the pulmonary arteries (VDNR: 25.5±10 vs. 20.6±6.5; CNR: 24.5±5.4 vs. 17.4±6.4; P<.01), and in the coronary arteries (VDNR: 25.9±8.2 vs. 18.9±4.9; CNR: 24.9±8.2 vs. 15.6±4.6; P<.01). There were fewer artifacts in the coronary arteries on 128-DSCT than on 64-MDCT (3 vs. 34 nondiagnostic segments; P<.001), and the ED in 128-DSCT was lower than in 64-MDCT (13.77±4 vs. 2.77±0.6 mSv; P<.001). ConclusionIn triple rule-out studies, high pitch 128-DSCT delivers a lower dose of radiation and provides better image quality than retrospective acquisition with 64-MDCT.

Quantification of Non-Calcified and Calcified Coronary Plaques Using 64-Slice MDCT in Patients with Acute Coronary Syndrome

Purpose: To investigate the accuracy of 64-row MDCT to analyze and quantify coronary arterial plaques in patients presented with acute coronary syndrome (ACS). Patients and methods: Between April 2010 and December 2013, 50 patients presented with acute cardiac chest pain were categorized into 2 groups according to their diagnosis based on clinical evaluation, ECG findings and cardiac biomarkers; group A including patients with ACS and group B including patients with stable angina (SA). Both groups underwent 64-row multidetector CT (MDCT) coronary arterial imaging. For each plaque, stenosis percentage was evaluated and the plaque was quantified using software (Sureplaque®) based on the density (HU) and percentage of its individual components including lipid, soft tissue, and calcium density. Results: Of the 50 patients; 24 and 26 were grouped into groups A & B respectively. The mean value of stenosis percent of the proximal & middle coronary segments of group A patients = 77.2% ± 10.2% - 90.5% ± 58.4% and 79.5% ± 9.1% - 85.25% ± 11% respectively, while in group B = 54.1% ± 12.1% - 65.2% ± 18.4% & 53.3% ± 1.5% - 68.6% ± 11.7% respectively (p=0.00-0.001). Quantification showed a mean value of lipid content percentage of group A = 15.4% ± 0.8% - 47.7 % ± 19.2 %, while in group B = 7.2% ± 5.5% - 10.3% ± 8.2% (p=0.008–0.001). The mean value of soft tissue content percentage in group A = 15.4% ± 0.8% - 47.7 % ± 19.2 %, while in group B = 7.2% ±5.5% - 10.3% ± 8.2%. The calcification content percentage in group A = 18% ± 8.7% - 35.1 % ± 16 %, while in group B = 66.4% ± 13.8% - 76.7% ± 16.5%. Conclusion: 64-row MDCT angiographic quantification software provides a good basis for the future attempts of proper risk stratification of patients with coronary artery disease especially those liable for developing ACS.

Feasibility of tissue characterization of coronary plaques using 320-detector row computed tomography: comparison with integrated backscatter intravascular ultrasound

Recently, a new generation of multi-detector row computed tomography (CT) with 320-detector rows (DR) has become available in the clinical settings. The purpose of the present study was to determine the cutoff values of Hounsfield unit (HU) for discrimination of plaque components by comparing HU of coronary plaques with integrated backscatter intravascular ultrasound (IB-IVUS) serving as a gold standard. Seventy-seven coronary atherosclerotic lesions in 77 patients with angina were visualized by both 320-DR CT (Aquilion One, Toshiba, Japan) and IB-IVUS at the same site. To determine the thresholds for discrimination of plaque components, we compared HU with IB values as a gold standard. Optimal thresholds were determined from receiver operating characteristic (ROC) curves analysis. The HU values of lipid pool (n = 115), fibrosis (n = 93), vessel lumen and calcification (n = 73) were 28 ± 19 HU (range -18 to 69 HU), 98 ± 31 HU (44 to 195 HU), 357 ± 65 HU (227 to 534 HU) and 998 ± 236 HU (366 to 1,489 HU), respectively. The thresholds of 56 HU, 210 HU and 490 HU were the most reliable predictors of lipid pool, fibrosis, vessel lumen and calcification, respectively. Lipid volume measured by 320-DR CT was correlated with that measured by IB-IVUS (r = 0.63, p < 0.05), whereas fibrous volume measured by 320-DR CT was not. Lipid volume measured by 320-DR CT was correlated with that measured by IB-IVUS, whereas fibrous volume was not correlated with that measured by IB-IVUS because manual exclusion of the outside of vessel hindered rigorous discrimination between fibrosis and extravascular components.

Central emboli rather than saddle emboli predict adverse outcomes in patients with acute pulmonary embolism

IntroductionIn patients with acute pulmonary embolism (PE), the prognostic implications of saddle or central emboli, as observed on computed tomography (CT), remain to be established. The aim of the present study was to assess whether the presence of saddle and central emboli could be used to predict clinical outcomes in patients with PE. Materials and MethodsThe authors retrospectively reviewed 743 consecutive patients hospitalized at a tertiary referral center with a diagnosis of PE based on multi-detector row CT scan. ResultsAll the clinical variables did not differ between saddle emboli (5.8% [n=43]) and right or left pulmonary artery emboli (29.7% [n=221]), and the frequency of an adverse outcome was not significantly different between the two groups. Saddle emboli and right or left pulmonary artery emboli were grouped into central emboli (35.5% [n=264]). Patients were allocated to an adverse outcome group (10.5% [n=78]) or a control group (89.5% [n=665]). Multivariate analysis demonstrated that PE severity index (PESI) score (class IV-V), N-terminal-pro-B-type natriuretic peptide level (≥1,406pg/mL), right ventricular dilation on CT (right ventricle/left ventricle diameter ratio ≥1), and central emboli significantly predicted an adverse outcome. The addition of central emboli to other established prognostic factors such as PESI enhanced the positive predictive values and positive likelihood ratios of an adverse outcome for acute PE. ConclusionsRather than saddle emboli, central emboli could be an independent prognostic factor of adverse outcomes in patients with acute PE and provide additional prognostic value when combined with other prognostic factors.

Computed tomography and clinical characteristics of gastric glomus tumors.

To provide a retrospective assessment of clinical characteristics of the patients with gastric glomus tumors and the imaging features of the tumors on multidetector row computed tomography (MDCT). Consecutive patients with gastric glomus tumor which was confirmed by postoperative pathology from January 2004 to January 2012 in a tertiary hospital were included in the study. The MDCT images and medical records of the patients including the imaging features of the tumor on MDCT such as its location, number, shape, growth pattern, size, density and enhancement pattern were retrospectively reviewed. Altogether ten patients were included in the study, including seven women and three men, with a mean age of 46.6 years (range 25-67 years). Most patients had nonspecific clinical symptoms. All lesions were located at the gastric antrum, with a mean diameter of 2.7 cm. The gastric glomus tumor showed strong enhancement at the arterial phase, a progressive filled-in enhanced pattern and prolonged enhancement during multiphasic scans. Gastric glomus tumor is clinically an extremely rare disease. The combination of tumor location, size and the characteristic enhancement pattern of the subepithelial lesion may suggest a diagnosis of gastric glomus tumor.

Insights Into New-Onset Rhythm Conduction Disorders Detected by Multi-Detector Row Computed Tomography After Transcatheter Aortic Valve Implantation

New-onset rhythm conduction disorders are frequent after transcatheter aortic valve implantation (TAVI). Multidetector row computed tomography may shed light on the pathophysiology of rhythm conduction disorders in patients who undergo TAVI with the Edwards SAPIEN valve. A total of 94 patients (mean age 81 ± 7 years, 48% men) treated with TAVI with the Edwards SAPIEN valve who underwent pre- and post-TAVI multidetector row computed tomography were included. Patients with preexisting right bundle branch block or left bundle branch block (LBBB) and permanent pacemakers were excluded. Pacemaker implantation or new-onset LBBB at 1-month follow-up was the combined end point. Overall, 1 pacemaker was implanted, and 14 cases of new-onset LBBB were recorded. Among several clinical and multi-detector row computed tomographic variables, overexpansion of the transcatheter valve >15% of native annular area (odds ratio 5.277, 95% confidence interval 1.398 to 19.919, p = 0.014) and depth of frame into the left ventricular outflow tract (odds ratio 1.401, 95% confidence interval 1.066 to 1.770, p = 0.010) were independently related to the need for a pacemaker or new-onset LBBB. In conclusion, overexpansion of the transcatheter prosthesis by >15% of native aortic annular area and implantation depth of the frame into the left ventricular outflow tract were independently associated with the need for a pacemaker or new-onset LBBB in patients who underwent TAVI with the Edwards SAPIEN valve.

In vitro dose measurements in a human cadaver with abdomen/pelvis CT scans.

To present a study of radiation dose measurements with a human cadaver scanned on a clinical CT scanner. Multiple point dose measurements were obtained with high-accuracy Thimble ionization chambers placed inside the stomach, liver, paravertebral gutter, ascending colon, left kidney, and urinary bladder of a human cadaver (183 cm in height and 67.5 kg in weight) whose abdomen/pelvis region was scanned repeatedly with a multidetector row CT. The flat energy response and precision of the dosimeters were verified, and the slight differences in each dosimeter's response were evaluated and corrected to attain high accuracy. In addition, skin doses were measured for radiosensitive organs outside the scanned region with OSL dosimeters: the right eye, thyroid, both nipples, and the right testicle. Three scan protocols were used, which shared most scan parameters but had different kVp and mA settings: 120-kVp automA, 120-kVp 300 mA, and 100-kVp 300 mA. For each protocol three repeated scans were performed. The tube starting angle (TSA) was found to randomly vary around two major conditions, which caused large fluctuations in the repeated point dose measurements: for the 120-kVp 300 mA protocol this angle changed from approximately 110° to 290°, and caused 8%-25% difference in the point dose measured at the stomach, liver, colon, and urinary bladder. When the fluctuations of the TSA were small (within 5°), the maximum coefficient of variance was approximately 3.3%. The soft tissue absorbed doses averaged from four locations near the center of the scanned region were 27.2±3.3 and 16.5±2.7 mGy for the 120 and 100-kVp fixed-mA scans, respectively. These values were consistent with the corresponding size specific dose estimates within 4%. The comparison of the per-100-mAs tissue doses from the three protocols revealed that: (1) dose levels at nonsuperficial locations in the TCM scans could not be accurately deduced by simply scaling the fix-mA doses with local mA values; (2) the general power law relationship between dose and kVp varied from location to location, with the power index ranged between 2.7 and 3.5. The averaged dose measurements at both nipples, which were about 0.6 cm outside the prescribed scan region, ranged from 23 to 27 mGy at the left nipple, and varied from 3 to 20 mGy at the right nipple over the three scan protocols. Large fluctuations over repeated scans were also observed, as a combined result of helical scans of large pitch (1.375) and small active areas of the skin dosimeters. In addition, the averaged skin dose fell off drastically with the distance to the nearest boundary of the scanned region. This study revealed the complexity of CT dose fluctuation and variation with a human cadaver.

Iodine quantification to distinguish clear cell from papillary renal cell carcinoma at dual-energy multidetector CT: a multireader diagnostic performance study.

To investigate whether dual-energy multidetector row computed tomographic (CT) imaging with iodine quantification is able to distinguish between clear cell and papillary renal cell carcinoma ( RCC renal cell carcinoma ) subtypes. In this retrospective, HIPAA-compliant, institutional review board-approved study, 88 patients (57 men, 31 women) with diagnosis of either clear cell or papillary RCC renal cell carcinoma at pathologic analysis, who underwent contrast material-enhanced dual-energy nephrographic phase study between December 2007 and June 2013, were included. Five readers, blinded to pathologic diagnosis, independently evaluated all cases by determining the lesion iodine concentration on color-coded iodine maps. The receiving operating characteristic curve analysis was adopted to estimate the optimal threshold for discriminating between clear cell and papillary RCC renal cell carcinoma , and results were validated by using a leave-one-out cross-validation. Interobserver agreement was assessed by using an intraclass correlation coefficient. The correlation between tumor iodine concentration and tumor grade was investigated. A tumor iodine concentration of 0.9 mg/mL represented the optimal threshold to discriminate between clear cell and papillary RCC renal cell carcinoma , and it yielded the following: sensitivity, 98.2% (987 of 1005 [95% confidence interval: 97.7%, 98.7%]); specificity, 86.3% (272 of 315 [95% confidence interval: 85.0%, 87.7%]); positive predictive value, 95.8% (987 of 1030 [95% confidence interval: 95.0%, 96.6%]); negative predictive value, 93.7% (272 of 290 [95% confidence interval: 92.8%, 94.7%]); overall accuracy of 95.3% (1259 of 1320 [95% confidence interval: 94.6%, 96.2%]), with an area under the curve of 0.923 (95% confidence interval: 0.913, 0.933). An excellent agreement was found among the five readers in measured tumor iodine concentration (intraclass correlation coefficient, 0.9990 [95% confidence interval: 0. 9987, 0.9993). A significant correlation was found between tumor iodine concentration and tumor grade for both clear cell (τ = 0.85; P < .001) and papillary RCC renal cell carcinoma (τ = 0.53; P < .001). Dual-energy multidetector CT with iodine quantification can be used to distinguish between clear cell and papillary RCC renal cell carcinoma , and it provides insights regarding the tumor grade.