Brian S. Kuszyk

Skeletal 3-D CT: advantages of volume rendering over surface rendering.

Abstract Both surface rendering and volume rendering have been extensively applied to CT data for 3-D visualization of skeletal pathology. This review illustrates potential limitations of each technique by directly comparing 3-D images of bone pathology created using volume rendering and surface rendering. Surface renderings show gross 3-D relationships most effectively, but suffer from more stairstep artifacts and fail to effectively display lesions hidden behind overlying bone or located beneath the bone cortex. Volume-rendering algorithms effectively show subcortical lesions, minimally displaced fractures, and hidden areas of interest with few artifacts. Volume algorithms show 3-D relationships with varying degrees of success depending on the degree of surface shading and opacity. While surface rendering creates more three-dimensionally realistic images of the bone surface, it may be of limited clinical utility due to numerous artifacts and the inability to show subcortical pathology. Volume rendering is a flexible 3-D technique that effectively displays a variety of skeletal pathology with few artifacts.

Dural ectasia in the Marfan syndrome: MR and CT findings and criteria

Purpose: To create criteria for detecting dural ectasia on MR or CT images in adult Marfan patients.Methods: Images were analyzed using a workstation. Parameters that predicted dural ectasia were included in our criteria.Results: Major criteria include: (1) width of dural sac below L5 > width above L4; (2) anterior sacral meningocele. Minor criteria include: (1) L5 nerve root sleeve diameter > 6.5 mm and (2) S1 scalloping > 3.5. Dural ectasia exists if 1 major or 2 minor criteria are present.Conclusion: MR and CT diagnose dural ectasia with high specificity and sensitivity. Our criteria accurately diagnose dural ectasia in adult Marfan patients.

Dural ectasia is associated with back pain in Marfan syndrome

Study Design. A cross-sectional age- and sex-matched study comparing the prevalence and size of dural ectasia in two groups of patients with Marfan syndrome. Group I comprised patients with moderate to severe back pain and Group II comprised patients without back pain. Objectives. To determine whether the presence and size of dural ectasia is associated with back pain in patients with Marfan syndrome. Summary of Background Data. Dural ectasia is present in more than 60% of patients with Marfan syndrome. Moderate to severe back pain is present in more than 50% of patients with Marfan syndrome. Most cases of significant low back pain in patients with Marfan syndrome do not have a clear cause. It would be useful for the clinician to know whether dural ectasia may be a cause of back pain in patients with Marfan syndrome with no other source. Methods. Thirty two volunteers aged 30–50 with Marfan syndrome were enrolled as age- and sex-matched pairs with significant back pain (Group I) and without back pain (Group II). A completed questionnaire, physical examination, and magnetic resonance image of the lumbosacral spine were obtained. Dural volume caudal to L5 was calculated from the magnetic resonance data by specially designed software. Results. Dural ectasia was present in 76% of the patients in Group I, and 41% of the patients in Group II. The proportion of patients with dural ectasia was significantly higher in Group I. Furthermore, the mean dural volume was significantly higher in Group I, and a significant correlation between dural volume and Oswestry pain score was noted. Conclusions. The presence and size of dural ectasia are associated with back pain in the Marfan syndrome. However, a high prevalence of dural ectasia (41%) exists even in patients with Marfan syndrome without back pain. The mere presence of dural ectasia therefore does not necessarily mean the patient will be symptomatic even though the two are associated.

Surgical planning for liver resection

Surgical resection is the cornerstone of curative therapy for primary and metastatic liver tumors. For best results, the surgeon must know the location of all hepatic tumor nodules relative to the major vessels that define the livers surgical anatomy. Computed tomography is very sensitive for detecting liver tumors, but its planar slices do not fully address the three-dimensional nature of this surgical problem. We have developed a technique using volume rendering of computed tomography data that provides a preoperative 3D map of the liver showing tumor location relative to key blood vessels. This technique also has important implications for emerging, minimally invasive therapies.

Osseous anatomy of the lumbosacral spine in Marfan syndrome.

Study Design. This study examines pedicle widths, laminar thicknesses, and scalloping values for lumbosacral spine elements in Marfan volunteers. Comparisons were made between these measurements and norms as well as measurements between Marfan patients with and without dural ectasia. Objectives. To determine if the lumbosacral vertebral elements are altered in the patient with Marfan syndrome. Summary of Background Data. Several abnormalities have been noted in Marfan lumbar spine, including pedicular attenuation and widened interpediculate distances. This may be due to abnormalities of growth or presence of dural ectasia. Given the large numbers of Marfan patients requiring spinal surgery and the high postoperative failure rate, better understanding of the bony anatomy of Marfan lumbar spine is necessary, especially if use of instrumentation is anticipated. Methods. Thirty-two volunteers with Marfan syndrome based on the Ghent criteria underwent spiral computed tomography of the lumbosacral spine. Images were evaluated for dural ectasia, and measurements of pedicle width, laminar thickness, and vertebral scalloping were made. Results. Pedicle widths and laminar thicknesses were significantly smaller in Marfan patients at all levels (P < 0.001). Mean pedicle widths at L1–L3 were smaller than the smallest available pedicle screw (5 mm). In Marfan patients with dural ectasia, laminar thickness from L5–S2 and pedicle widths at all lumbar levels were significantly reduced (P < 0.01). Vertebral scalloping at S1 was significantly greater in Marfan patients with dural ectasia (P = 0.02). Conclusion. Lumbar pedicle width and laminar thickness are significantly reduced in Marfan individuals. Those with dural ectasia demonstrate increased bony erosion of anterior and posterior elements of lumbosacral spine. Preoperative planning and routine computed tomography scans are recommended when operating on Marfan lumbosacral spine.

Subcutaneously Tethered Temporary Filter: Pathologic Effects in Swine

PURPOSE To evaluate the histopathologic effects of the Tempo-filter, a temporary caval filter, on the caval wall and determine the feasibility of deployment and removal of the device in swine. MATERIALS AND METHODS Filters were placed in the infrarenal inferior vena cava of 11 swine. The tethering catheter was sutured in a subcutaneous pocket near the puncture site. The original tethering catheter used in humans and a stiffer catheter designed to prevent migration in swine were evaluated. Postplacement, mid-study, and preexplant vena cavography procedures were performed. Four swine underwent in situ dissection at 3-10 weeks. Filters were removed from seven animals just before they were killed at 1-6 weeks. RESULTS All filters were successfully placed. All seven filters were successfully removed at up to 6 weeks after placement. Cephalic migration of more than 1 cm was observed in 10 of 11 swine (100% of original catheters, 83% of stiff catheters). Other complications were more common with stiffer tethering catheters, including caval stenosis in 40% of original catheters and 100% of stiff catheters, filter cone thrombus in 0% and 67%, tethering catheter thrombus in 20% and 83%, pulmonary embolism in 0% and 50%, and death in 0% and 17%, respectively. There was mild vessel wall damage in the vena cava. CONCLUSION Placement of the Tempofilter and removal at up to 6 weeks after placement is feasible.

Technical aspects of CT angiography

The basic tasks of spiral CT acquisition, image processing, and image display are the foundations underlying CT angiography regardless of the anatomic region of interest. Volume rendering is a rapidly emerging image processing technique for creating three-dimensional (3D) images from CT datasets, which has important advantages over other 3D rendering techniques including maximum intensity projection and surface rendering. This articles reviews the techniques that are commonly used in CT angiography and key considerations for optimization.

Neurovascular applications of CT angiography

CT angiography, which has important advantages over both MR and ultrasound, is rapidly becoming an important modality for noninvasive evaluation of the neurovasculature. This article discusses CT angiography techniques for imaging the neurovasculature, including spiral acquisition protocols and image processing techniques, with a focus on the use of volume rendering for three-dimensional visualization. The clinical results for CT angiography of the cervical carotid arteries, intracranial aneurysms, arteriovenous malformations, and emerging work in the evaluation of acute stroke are reviewed. Important areas of ongoing research also are described.

Angioarchitecture of pulmonary arteriovenous malformations: Characterization using volume-rendered 3-D CT angiography

Pulmonary arteriovenous malformations (PAVMs) are congenital abnormal communications between the pulmonary artery and pulmonary vein, forming a fight-to-left shunt. Patients present with symptoms of hypoxemia, paradoxical emboli, and/or, less commonly, rupture of the PAVM and hematemesis. They can occur sporadically or in association with heredity hemorrhagic telangectasia (HHT) [1]. Embolotherapy is currently the treatment of choice. Investigators have shown a significant improvement in PaO 2 after embolization with very few complications [1-3]. It is critical that the angioarchitecture of the PAVM be elucidated prior to embolization. Historically, this was done exclusively by angiography. With the advent of helical computed tomography, a noninvasive mapping technique has emerged. The angioarchitecture of PAVMs can be accurately depicted by analysis of both the axial and 3-D reconstructed images 14, 5]. The following is a pictorial review of PAVMs, with emphasis on the complex type, and the benefits of using 3-D computed tomography (CT) volume rendering for diagnosis, angioarchitecture characterization, and preembolization planning [6].

Cryptococcoma of the sacrum

Abstract Cryptococcoma of the sacrum was the initial presentation of systemic cryptococcosis in a patient on chronic steroid therapy for autoimmune hepatitis. The bone lesion was the only overt manifestation of systemic cryptococcal disease, which preceded other clinical manifestations and led to the subsequent diagnosis of systemic infection.