Multidetector Spiral Computed Tomography Research Articles

Coronary artery calcifications in children with end-stage renal disease

Coronary artery calcification (CAC) is common in adults with end-stage renal disease (ESRD), but little is known about the prevalence and the extent of it in children. We used multidetector spiral computed tomography (MDCT), echocardiography, and carotid and brachial high-resolution ultrasonography to screen for the presence and predisposing factors of CAC in 53 children with ESRD [15 hemodialysis (HD) patients, 24 peritoneal dialysis (PD) patients, and 14 renal transplant (rTx) recipients]. CAC was present in 15% of patients (three HD patients, three PD patients, and two rTx). The mean age of the patients with CAC was 16.4 years (range: 11.0-21.2 years), and their median CAC score was 101.3, ranging from 8.5 to 4,322 according to the Agatston method. The patients with CAC had longer duration of total dialysis (P=0.005), had higher time-integrated serum phosphorus (P<0.001), calcium-phosphate (CaxP) product (P=0.012), intact parathyroid hormone (P=0.010), vitamin B(12) levels (P=0.010), the amount of cumulative calcium-containing oral phosphate binders (OBPs) (P<0.001), and calcitriol intake (P<0.001), and had lower serum hemoglobin level (P=0.014). Interventricular septum systolic thickness (P=0.033) was significantly higher, relative wall thickness (P=0.062) tended to be higher, and flow-mediated endothelium-dependent dilatations (P=0.071) were lower without reaching statistically significant levels in those with CAC. A stepwise logistic regression analysis revealed that serum phosphorus (P=0.018) and the cumulative exposure to calcium-containing OPBs (P=0.016) were the most significant independent predictors in the development of CAC. These results indicate that even adolescents and children with ESRD may have coronary calcifications. We concluded that impaired divalent ion metabolism is the main factor in the formation of CAC in this age group.

Coronary bypass graft patency cannot be determined by multidetector spiral computed tomography

Objectives. Angiography by selective catheterization is the reference standard for coronary bypass graft patency assessment but carries a risk of serious complications. We have investigated whether 16-slice multidetector spiral computed tomography (MDCT) can substitute for selective angiography. Design. Two to three years after coronary artery bypass grafting, 45 patients with a total of 156 bypasses (100 single and 28 sequential grafts) were examined with both MDCT and conventional selective angiography on the same day. The bypasses were classified as patent, stenotic or occluded. Results. The likelihood ratio for MDCT-detected occlusion was 40, reflecting a fairly high combined sensitivity and specificity. However, 24% of the distal anastomoses could not be evaluated by MDCT, mainly because of respiratory movements, artifacts due to metal clips, and small vessel dimensions. Moreover, seven out of 117 bypasses (6%) deemed evaluable by MDCT were wrongly classified by this method. Conclusions. At present, 16-slice MDCT cannot replace selective angiography for assessment of coronary bypass graft patency since 24% of bypasses could not be evaluated by this method, and an error rate of 6% is unacceptable.

Reproducibility of multi-detector spiral computed tomography in detection of sub-segmental acute pulmonary embolism

The aim of this study was to evaluate the inter-observer and intra-observer agreement of the diagnosis of sub-segmental acute pulmonary embolism (PE) in an inpatient population explored by 16 slice multi-detector spiral computed tomography (MDCT). Four hundred consecutive inpatients were referred for MDCT for the clinical suspicion of acute PE. One hundred and seventy seven (44.2%) had a known cardio-respiratory disease at the time of examination. Inter-observer and intra-observer agreements for the diagnosis of acute PE and of sub-segmental acute PE were assessed blind and independently by three experienced readers and by kappa statistics. Seventy-five patients were diagnosed as having acute PE findings (19.5%), and clots were located exclusively within sub-segmental arteries in nine patients (12%). When clots were limited to sub-segmental or more distal branches of the pulmonary arteries, kappa values were found to be moderate (0.56) to very good (0.85) for the diagnosis of sub-segmental acute PE, whereas for the diagnosis of acute PE in the whole population, kappa values ranged from 0.84 to 0.97. Intra-observer agreement was found to be perfect (kappa=1). MDCT is a reproducible technique for the diagnosis of sub-segmental acute PE as well as for acute PE. In this inpatient population, sub-segmental acute PE was not a rare event.

Virtual colonography: Identification and differentiation of colorectal lesions using multi-detector computed tomography

Objective.Early detection of precancerous or malignant lesions may be decisive for prognosis of patients with colorectal cancer. In this prospective feasibility study, multi-detector spiral computed tomography (CT) colonography was compared with conventional colonoscopy for the detection of colorectal polyps.Material and methods.Seventy-eight patients underwent CT colonography (standard colonoscopy preparation, distension with room air, prone and supine position) immediately before colonoscopy. Sixty-five (83%) were asymptomatic screening subjects, while the rest had symptoms suggestive of colorectal disease. Presence, location, and size of lesions were prospectively assessed. Sensitivity, specificity, and positive and negative predictive values of CT colonography were calculated using conventional colonoscopy as the reference standard.Results.Conventional colonoscopy was normal in 52 patients. In 26 patients a total of 49 polyps and 3 carcinomas were identified. All three carcinomas and 39 polyps (80%) were identified by CT colonography. Seven of 7 polyps ≥10 mm (100%), 13 of 16 polyps of 6 to 9 mm (81%), and 19 of 26 polyps ≤5 mm (73%) in diameter were identified. Fourteen false-positive findings (10 of which were ≤5 mm in diameter) were related to 8 patients (specificity at the patient level was 86%). In 10 patients, a total of 10 polyps were missed by CT colonography, 7 of which were ≤5 mm in diameter.Conclusions.In this feasibility study, multi-detector spiral CT colonography allows accurate detection of polyps>5 mm in diameter, but at the expense of low specificity in the small size range.

Accuracy of multidetector spiral computed tomography in identifying and differentiating the composition of coronary atherosclerotic plaques: A comparative study with intracoronary ultrasound

ObjectivesWe evaluated the accuracy of contrast-enhanced multidetector spiral computed tomography (MDCT) for the noninvasive detection and classification of coronary plaques and compared it with intracoronary ultrasound (ICUS). BackgroundNoninvasive determination of plaque composition and plaque burden may be important to improve risk stratification and to monitor progression of coronary atherosclerosis. MethodsWe included 46 consecutive patients with a distinctive risk profile, who were investigated by ICUS (Goldvision, 20 MHz, Jomed Inc., Rancho Cordova, California). Due to the inability to slow the heart rate below 65 beats/min (n = 7) and due to renal insufficiency (n = 2), nine of 46 consecutive patients could not be studied by MDCT (Sensation 16, Siemens, Forchheim, Germany). ResultsIn the remaining 37 patients, 68 vessels were investigated by ICUS, and 58 of these vessels were visualized by MDCT with image quality sufficient for analysis. In these vessels that were divided in 3-mm sections, MDCT correctly classified 62 of 80 (78%) sections containing hypoechoic plaque areas, 87 of 112 (78%) sections containing hyperechoic plaque areas, and 150 of 158 (95%) sections containing calcified plaque tissue. In 484 of 525 (92%) sections, atherosclerotic lesions were correctly excluded. The MDCT-derived density measurements within coronary lesions revealed significantly different values for hypoechoic (49 HU [Hounsfield Units] ± 22), hyperechoic (91 HU ± 22), and calcified plaques (391 HU ± 156, p < 0.02). ConclusionsThis study demonstrates that, in the case of diagnostic image quality, contrast-enhanced MDCT permits an accurate identification of coronary plaques and that computed tomography density values measured within plaques reflect echogenity and plaque composition.

Radiologic evaluation in planning surgery of renal tumors.

The evolution in diagnostic imaging modalities, mainly in computed tomography (CT) and magnetic resonance imaging (MRI), have made it possible to extend the applications of these techniques from diagnosis to staging and surgical planning. Nowadays, the possibility to present images on different planes with an intrinsic resolution close to that of the original axial sections allows presentation of the kidney on sagittal, coronal, and oblique planes. Three-dimensional reconstructions can be obtained with different methods and have attained excellent image quality. Multidetector spiral CT presently is the best technique for planning surgery, but MRI also enables high-quality images to be obtained if state-of-the-art equipment is available. This update reviews the current status and possibilities of diagnostic imaging modalities in planning surgery of renal tumors.

Computed tomography and magnetic resonance imaging: past, present and future

The aims of this paper are to summarize the current recommendations for the use of computed tomography (CT) and magnetic resonance imaging (MRI) in the chest and to suggest some possible future developments. The main developments of CT in the chest have been the introduction of high-resolution CT (HRCT), spiral CT and, more recently, multidetector spiral CT. HRCT is defined as thin-section CT (1- to 2-mm collimation scans), optimized by using a high-spatial resolution (edge-enhancing) algorithm. Several studies have shown that HRCT closely reflects macroscopic (gross) pathological findings. HRCT currently has the best sensitivity and specificity of any imaging method used for the assessment of focal and diffuse lung diseases. The advent of spiral CT and, more recently, multidetector CT scanners, has allowed for major improvements in the imaging of airways, pulmonary and systemic vessels, and lung nodules. Spiral CT facilitates multiplanar and three-dimensional display of structures and visualization of pulmonary and systemic vessels, with a level of detail that is comparable to that of conventional angiography. With the use of graphics-based software programs, spiral CT enables depiction of the luminal surface of the airways with images that resemble those of bronchoscopy (virtual bronchoscopy) or bronchography (virtual bronchography). Several studies have shown a high sensitivity and specificity for spiral CT in the diagnosis of acute pulmonary embolism. Therefore, spiral CT is rapidly becoming the imaging modality of choice in the diagnosis of pulmonary embolism. Like the radiograph, signal intensity on computed tomography is mainly due to a single parameter: electron density. The signal intensity of the magnetic resonance image depends on four parameters: nuclear density, two relaxation times called T1 and T2, and motion of the nuclei within the imaged lung volume. Abnormal soft tissue can be identified more easily through measurement of these four parameters than through use of computed tomography. Furthermore, because the spatial orientation of the image is determined by manipulation of magnetic fields, scans can be performed in any plane. The main indications for magnetic resonance in the chest have been in the evaluation of the heart, major vessels, mediastinum, and hilar structures because of the natural contrast provided by flowing blood. Of particular interest for the respirologist has been the recent development of magnetic resonance angiography. This technique consists of three-dimensional single breath-hold images obtained using gadolinium-based contrast agents. This is a promising technique for the diagnosis of acute and chronic pulmonary embolism.

Spiral CT arthrography of the postoperative knee.

Computed tomography (CT) has gained multiplanar capability and submillimeter spatial resolution due to the development of spiral acquisition mode and multidetector row technology. Multidetector spiral CT arthrography of the knee is a valuable imaging modality for the assessment of lesions of the meniscus, anterior cruciate ligament (ACL), and articular cartilage. This article presents the value of spiral CT arthrography in the assessment of the postoperative knee with emphasis on the postoperative meniscus, articular cartilage, and ACL graft. This technique may be proposed as an alternative to magnetic resonance arthrography.