Dental multisection CT for the placement of oral implants: technique and applications.

Dental computed tomography (CT) is a diagnostic examination for the preoperative evaluation of patients who will undergo placement of oral implants. It can be performed with multidetector CT or more recently with cone-beam CT. The growing older population and the consequent development of edentulism have increased the number of imaging studies performed for preoperative evaluation of dental implantation. Thus, radiologists are becoming more frequently involved in this type of testing. Dental CT is superior to conventional x-ray techniques because superimposition and distortion are eliminated; therefore, possible complications such as injury of the neurovascular bundle and perforation of the maxillary sinuses can be avoided. This noninvasive and fast method provides accurate information about the positions of important structures to allow one to determine the implant required. Dental CT enables analysis of the state, quality, and quantity of bone on two-dimensional and three-dimensional reformatted images, and its high spatial resolution allows exact measurements of the length and width of the alveolar ridge. Inclusion of all this information in the radiology report facilitates achievement of a successful implantation.

Uncommon congenital and acquired aortic diseases: role of multidetector CT angiography.

State-of-the-art multidetector computed tomographic (CT) technology has replaced invasive angiography for evaluation of patients suspected to have aortic disease. Although most aortic disease is associated with atherosclerosis (ie, aneurysms and dissection), the spectrum of aortic disease is vast and includes various congenital and acquired entities. Radiologists should also be familiar with uncommon aortic diseases, which are divided into those that are congenital in origin and acquired disorders, and with their findings at multidetector CT. The first group includes patent ductus arteriosus, aortic hypoplasia, aortic coarctation, interrupted aortic arch, aortopulmonary window, common arterial trunk, supravalvular aortic stenosis, and vascular rings. The acquired disorders include aortic dissection due to extension of a coronary artery dissection, Marfan syndrome, large-vessel vasculitis such as Takayasu arteritis, and mycotic aneurysms. Finally, specific conditions associated with therapeutic maneuvers--such as recoarctation, stent-graft rupture, and endoleaks--can also be assessed with multidetector CT. Multidetector CT is an alternative tool helpful in establishing the primary diagnosis, defining anatomic landmarks and their relationships, and identifying associated cardiovascular anomalies. It is also an adjunct in the evaluation of complications during follow-up.

Neurocysticercosis: radiologic-pathologic correlation.

Neurocysticercosis is a neurologic parasitic disease caused by the encysted larva of the tapeworm Taenia solium and is the most important parasitic disease of the human central nervous system. It is the most common cause of acquired epilepsy in endemic settings and constitutes a public health challenge for most of the developing world. Nowadays, however, as a result of globalization, neurocysticercosis is being seen more frequently in developed countries as well. Neurocysticercosis is acquired through fecal-oral contamination, and the disease course is complex, with two intermediate hosts (ie, pigs and humans) and a definitive host (humans). Traditionally, it has been classified into active and nonactive forms according to disease location. Radiologists must be aware of its imaging appearance, which is quite variable, as is the differential diagnosis. Imaging findings depend on several factors, including the stage of the life cycle of T solium at presentation; the number and location (ie, subarachnoid, cisternal, or intraventricular) of parasites; and associated complications such as vascular involvement (ie, arteritis with or without infarction), inflammatory response (ie, edema, gliosis, or arachnoiditis), and, in ventricular forms, degree of obstruction. Thus, the diagnostic approach, management, and prognosis for neurocysticercosis differ widely depending on the type of infection.

Coronary artery aneurysms and ectasia: role of coronary CT angiography.

Coronary artery dilatations-aneurysms and ectasia-are an uncommon and frequently unrecognized incidental finding in patients with coronary artery disease. Aneurysms and ectasia are associated with a vast group of disorders, and the evaluation and characterization of coronary aneurysms and ectasia represent a great diagnostic task with clinical and therapeutic implications. The underlying etiology is variable and includes degenerative, congenital, inflammatory, infectious, toxic, and traumatic causes. Unlike aneurysms, ectasia is more frequently seen in association with atherosclerosis or as a compensatory mechanism in those cases in which a proximal stenosis is noted in the opposite coronary artery; ectasia is also seen in some coronary artery anomalies, such as anomalous origin from the pulmonary artery, or as a result of a high-flow state, as seen in coronary artery fistulas. The diagnostic approach depends on the clinical scenario, and nowadays, noninvasive evaluation with multidetector computed tomography is possible. Imaging assessment should include evaluation of (a) the distribution, (b) maximal diameter, (c) presence or absence of intraluminal thrombi, (d) number, (e) extension, and (f) associated complications such as myocardial infarction. This article presents an overview of the definition, classification, etiology, clinical manifestations, and potential complications of coronary artery aneurysms and ectasia.

[Computer multidetector tomography of coronary arteries. State-of-the-art. Part 1. Technical aspects]. / Tomografía computada multidetector de arterias coronarias: estado del arte. Parte I: aspectos técnicos.

The study of atherosclerotic disease in coronary arteries is fundamental since it is the first cause of death in the Western hemisphere. The gold standard for its diagnosis is invasive angiography, but it contributes to an increase in costs for this group of patients. Nowadays fourth generation computed tomography (CT) equipments can construct acquisition data of up to 256 images in only 400 milliseconds (ms), which is 900 to 1000 times faster than first generation apparatus. CT multidetector (CTMD) is the noninvasive choice diagnosis method for a vascular evaluation of the thorax. Its role in the study of the heart was limited, but today it is possible to obtain three-dimensional heart and whole body images in only seconds. CTMD is a fast, low-cost, noninvasive method that generates cardiac and extra cardiac images without adjacent structure interference. The higher temporal resolution due to an increase of the gantry's rotation and new reconstruction algorithms, as well as its higher spatial resolution and elevated time acquisition due to the presence of more detectors, have permitted CTMD to give significantly better and precise diagnosis of coronary arteries.

Left ventricular noncompaction: a proposal of new diagnostic criteria by multidetector computed tomography.

BACKGROUND: Left ventricular noncompaction (LVNC) is a cardiomyopathy characterized by a noncompacted myocardial layer in the left ventricle, primarily diagnosed by echocardiographic and magnetic resonance criteria. Multidetector computed tomography (MDCT) is an imaging method that has been increasingly used in cardiac evaluation. However, tomographic criteria to diagnose LVNC have not been determined. OBJECTIVES: We assessed the structural characteristics of LVNC with MDCT and proposed tomographic criteria that may differentiate LVNC from healthy subjects and patients with other cardiomyopathies that might be associated with increased myocardial trabeculation. METHODS: Between March 2007 and June 2009 we studied 10 consecutive patients with LVNC diagnosed by echocardiogram and/or magnetic resonance imaging who underwent electrocardiogram-gated coronary CT angiography. We evaluated the ratio of noncompacted to compacted myocardium (NC/C ratio) in end diastole in each of the 17 segments established by the American Heart Association (excluding the apex). The results were compared with 9 healthy subjects, 14 patients with hypertrophic cardiomyopathy, and 17 patients with dilated cardiomyopathy to determine the cutoff that would distinguish patients with LVNC. RESULTS: When considering involvement of more than 1 segment, the NC/C ratio of 2.2 distinguished pathologic noncompaction, with sensitivity and specificity of 100% and 95%, respectively. In addition, the involvement of ≥2 segments allows the distinction of all patients with LVNC from other cardiomyopathies and from healthy subjects. CONCLUSIONS: LVNC can be accurately diagnosed with MDCT when using a cutoff NC/C ratio of 2.2 at end diastole involving ≥2 segments.

Tomografía computada multidetector de arterias coronarias: estado del arte. Parte I: aspectos técnicos / Computer multidetector tomography of coronary arteries: state-of-the-art. Part 1: technical aspects

The study of atherosclerotic disease in coronary arteries is fundamental since it is the first cause of death in the Western hemisphere. The gold standard for its diagnosis is invasive angiography, but it contributes to an increase in costs for this group of patients. Nowadays fourth generation computed tomography (CT) equipments can construct acquisition data of up to 256 images in only 400 milliseconds (ms), which is 900 to 1000 times faster than first generation apparatus. CT multidetector (CTMD) is the noninvasive choice diagnosis method for a vascular evaluation of the thorax. Its role in the study of the heart was limited, but today it is possible to obtain three-dimensional heart and whole body images in only seconds. CTMD is a fast, low-cost, noninvasive method that generates cardiac and extra cardiac images without adjacent structure interference. The higher temporal resolution due to an increase of the gantry's rotation and new reconstruction algorithms, as well as its higher spatial resolution and elevated time acquisition due to the presence of more detectors, have permitted CTMD to give significantly better and precise diagnosis of coronary arteries.