Three-dimensional volume-rendering CT angiography in vasculitis: spectrum of disease and clinical utility

Computed tomographic angiography in stroke and high-risk transient ischemic attack: Do not leave the emergency department without it!

Stroke is a major cause of morbidity and mortality worldwide, and effective treatment requires rapid diagnosis and recognition of relevant vascular lesions. In this review we will discuss the usefulness and versatility of computed tomography angiography in the setting of stroke, be it ischemic or hemorrhagic, minor or disabling. Furthermore, we also highlight how we use computed tomography angiography in decision making in transient ischemic attacks, acute disabling ischemic stroke, and hemorrhagic stroke.

Computed Tomography Angiography in the Assessment of Patients With Stroke/TIA

Rapid advance in medical technology has resulted in the availability of numerous tests and treatment strategies in the management of acute stroke. The increasingly evidence-based context of clinical medicine necessitates that clinicians use only appropriate tools to facilitate the diagnostic process and patient management. In this review, we seek to explore the use of computed tomography angiography (CTA) in the diagnosis and management of patients presenting with acute stroke (ischemic and hemorrhagic) or transient ischemic attack (TIA). We present evidence in favor of the use of CTA, highlight the disadvantages of this imaging modality, and present a heuristic model based on our experience at utilizing CTA for decision making in acute stroke and TIAs.

[Useful imaging techniques in the diagnosis and follow up of large vessel vasculitis: eco-doppler, angio-CT, angio-RM]

Although most vasculitis require histological proof for a definitive diagnosis, diagnostic imaging can be very helpful in this regard, allowing a proper evaluation of the vascular system and monitoring the response to treatment. Even though vasculitis is constituted by different pathological substrates, they show a common semiologic pattern from a radiological standpoint which is represented by inflammation, arterial wall thickening, and potential secondary development of vascular stenosis, occlusions or aneurysms. Differential diagnosis among diverse entities is based, beside clinical criteria, on the anatomical location and topography of the affected vascular territory. The general radiologic semiology is described in this paper from the perspective of the different imaging techniques, addressing their main advantages and drawbacks. Proper knowledge of this techniques will allow us to select the most appropiate one for each clinical condition.

Opacity transfer function optimization for volume-rendered computed tomography images of the prostate

RATIONALE AND OBJECTIVES

The selection of an opacity transfer function is essential for volume visualization. Computed tomography (CT) scans of the pelvis were used to determine an optimal opacity transfer function for use in radiotherapy.

MATERIALS AND METHODS

On sample datasets (a mathematical phantom and a patient pelvis CT scan), standard viewing orientations were selected to render the prostate. Opacity functions were selected via (1) trapezoidal manual selection, (2) trapezoidal semiautomatic selection, and (3) histogram volume-based selection. Using an established metric, the errors using each of these methods were computed.

RESULTS

Trapezoidal manual opacity function optimization resulted in visually acceptable images, but the errors were considerable (6.3-9.1 voxel units). These errors could be reduced with the use of trapezoidal semiautomatic selection (4.9-6.2 voxel units) or with histogram volume-based selection (4.8-7.9 voxel units). As each visualization algorithm focused on enhancing the boundary of the prostate using a different approach, the scene information was considerably different using the three techniques.

CONCLUSION

Improved volume visualization of soft tissue interfaces was achieved using automated optimal opacity function determination, compared with manual selection.

Radiologic investigation of rheumatic diseases

This article reviews the current use of the wide variety of imaging modalities now available, presenting the imaging features of common and important causes of acute and chronic rheumatic disorders including juvenile idiopathic arthritis, spondyloarthropathies/enthesitis-related arthritis, sepsis, autoimmune diseases, vasculitis, and osteoporosis.

New developments in imaging for diagnosis and therapy monitoring in rheumatic diseases

The availability of therapeutic modalities that are able to stop inflammatory joint damage has also markedly influenced recent developments in muskuloskeletal imaging. One focus of interest is the detection of joint pathology as early as possible in order to prevent erosive bony changes. Ultrasonography and magnetic resonance imaging are the most valuable technologies in this respect. Another focus is on the exact assessment and documentation of joint damage using scoring systems not only in therapeutic trials, but also in clinical practice. In addition to these recent advances in peripheral and axial joint imaging, this chapter also discusses advances in vascular imaging and scintigraphy in rheumatoid diseases as well as interventional procedures guided by imaging technologies.

Multislice CT angiography: a practical guide to CT angiography in vascular imaging and intervention

The development of multidetector CT (MDCT) has revolutionized CT angiography (CTA). Not only are new techniques now in the remit of CTA, but all the studies previously performed on single slice or helical CT can now be done with better resolution. The advantage of MDCT relevant to CTA is the ability to acquire high resolution, near isotropic data sets in a shorter acquisition time. Also important is the ability to achieve a longer scanning range in the arterial phase, which has seen the introduction of CTA of the peripheral arterial system. Image processing techniques have also progressed rapidly, with simplification of a previously cumbersome process. The high spatial resolution and relatively non-invasive nature make MDCT angiography a strong and serious competitor to established vascular imaging techniques. The implication is that traditional diagnostic pathways for evaluation of the vascular system have changed.

Vascular imaging

Many rheumatic diseases affect the vasculature, either as a 'primary' manifestation of the disease process (as in vasculitis or scleroderma-spectrum disorders) or as a result of accelerated atherosclerosis. Recent years have seen very major developments in, and refinements of, vascular imaging methods. It is likely that this pace of development will continue, enhancing the rheumatologist's ability to diagnose different musculoskeletal conditions and follow their progression, using minimally invasive techniques. In this chapter, we describe these recent advances in vascular imaging techniques, concentrating on those most relevant to the practising clinician, but also discussing methods which are being used in clinical research. Three main groups of imaging modalities are described: large vessel imaging (X-ray, magnetic resonance (MR) and computed tomography (CT) angiography), nailfold microscopy and thermography. For each of these, the method(s) and then the clinical and research applications are discussed. Laser Doppler, a research technique, is also described.

Value of 3D-volume rendering in the assessment of coronary arteries with retrospectively ECG-gated multislice spiral CT

PURPOSE

To assess the diagnostic value and measurement precision of 3D volume rendering technique (3D-VRT) from retrospectively ECG-gated multislice spiral CT (MSCT) data sets for imaging of the coronary arteries.

MATERIAL AND METHODS

In 35 patients, retrospectively ECG-gated MSCT of the heart using a four detector row MSCT scanner with a standardized examination protocol was performed as well as quantitative X-ray coronary angiography (QCA). The MSCT data was assessed on segmental basis using 3D-VRT exclusively. The coronary artery diameters were measured at the origin of each main coronary branch and 1 cm, 3 cm and 5 cm distally. The minimum, maximum and mean diameters were determined from MSCT angiography and compared to QCA.

RESULTS

A total of 353 of 525 (67.2%) coronary artery segments were assessable by MSCT angiography. The proximal segments were more often assessable when compared to the distal segments. Stenoses were detected with a sensitivity of 82.6% and a specificity of 92.8%. According to the Bland-Altman method the mean differences between QCA and MSCT ranged from -0.55 to 1.07 mm with limits of agreement from -2.2 mm to -2.7 mm.

CONCLUSION

When compared to QCA, the ability of 3D-VRT to quantitatively assess coronary artery diameters and coronary artery stenoses is insufficient for clinical purposes.

Aortitis

Aortitis is defined as an inflammatory process that involves one or more layers of the aortic wall (internal elastic lamina, tunica media, and adventitia) and can be caused by multiple mechanisms. Clinical features are usually nonspecific and a high index of suspicion is required for making the diagnosis. Although noninvasive imaging studies are being increasingly used in evaluating patients for diagnosis, angiography remains the gold standard for confirming aortic involvement. When tissue is available, pathologic examination can aid in clarifying the diagnosis. Aortitis, irrespective of the underlying cause, frequently displays similar clinical, pathologic, and arteriographic features and therefore understandably presents a therapeutic and diagnostic dilemma. Whatever the cause, early identification and aggressive treatment is required in order to avert the potentially life-threatening sequelae. The treatment of aortitis is determined by the underlying cause. If diagnosed early, infectious aortitis responds to appropriate antimicrobial therapy, whereas noninfectious, immune-mediated aortitis requires immunosuppressive therapy. However, in many instances, primarily because of the delay in diagnosis, surgical intervention is necessary to treat the associated anatomic and physiologic sequelae. Less definitive and more controversial is the role of inflammation in both primary and secondary accelerated atherosclerosis of the aorta and its modality of treatment.