Left sided cervical and thoracic malignant extra-adrenal pheochromocytoma.

Extra-adrenal Pheochromocytomas are rare entities. High index of suspicion among diastolic hypertensives followed by screening test for 24-hour urinary catecholamine level helps in diagnosis. 123I MIBG scintigraphy is specific for tumour localisation and surgical debulking of tumour or 131I MIBG therapy are alternative modes of treatment.

Hepatic MR angiography: a multiobserver comparison of visualization methods.

OBJECTIVE: MR angiography (MRA) is an established diagnostic method; however, controversy remains over the best technique for display. In this study, we compared five methods of depicting hepatic MRA, including a novel skeletonization approach, using receiver operator characteristic (ROC) curves, interobserver variability (kappa values), and speed of interpretation. SUBJECTS AND METHODS: Twenty-one patients scheduled for isolated liver perfusion therapy for metastatic disease underwent contrast-enhanced three-dimensional MRA to determine vascular anatomy. Vascular anatomy was validated at the time of surgery. We displayed the image data, using five techniques: maximum intensity projection, targeted maximum intensity projection, isointensity surface (isosurface), connected isointensity surface (connected isosurface), and ordered region growing skeleton (skeleton). Four observers, blinded to the surgical results, interpreted each technique in random order without patient identifiers. Areas under the ROC curves, kappa values of interobserver variability, and time to interpret each display were compared. RESULTS: Skeletonized MRA had the highest area under the ROC curve (A(z), 0.90 +/- 0.04) compared with the other techniques (p < 0.013). Kappa scores of agreement were also highest for skeletonized MRA (0.75 +/- 0.04) and had no overlap at the 95% confidence level compared with other techniques. Compared with source images, all visualization methods were faster to interpret, but the skeleton technique was more quickly (p = 0.04) interpreted than the other techniques. CONCLUSION: Skeletonized MRA with the skeleton connectivity algorithm is a semi-automated method of displaying complex arterial anatomy. Compared with other techniques, it is more accurate, more consistent among observers, and slightly faster to interpret. Skeletonization should be applicable to CT angiography and MRA.

Vessel surface reconstruction with a tubular deformable model.

Three-dimensional (3-D) angiographic methods are gaining acceptance for evaluation of atherosclerotic disease. However, measurement of vessel stenosis from 3-D angiographic methods can be problematic due to limited image resolution and contrast. We present a method for reconstructing vessel surfaces from 3-D angiographic methods that allows for objective measurement of vessel stenosis. The method is a deformable model that employs a tubular coordinate system. Vertex merging is incorporated into the coordinate system to maintain even vertex spacing and to avoid problems of self-intersection of the surface. The deformable model was evaluated on clinical magnetic resonance (MR) images of the carotid (n = 6) and renal (n = 2) arteries, on an MR image of a physical vascular phantom and on a digital vascular phantom. Only one gross error occurred for all clinical images. All reconstructed surfaces had a realistic, smooth appearance. For all segments of the physical vascular phantom, vessel radii from the surface reconstruction had an error of less than 0.2 of the average voxel dimension. Variability of manual initialization of the deformable model had negligible effect on the measurement of the degree of stenosis of the digital vascular phantom.

Automatic determination of LV orientation from SPECT data.

Presents a new method to determine the orientation or pose of the left ventricle (LV) of the heart from cardiac SPECT (single photon emission computed tomography) data. This proposed approach offers an accurate, fast, and robust delineation of the LV long-axis. The location and shape of the generated long-axis can then be utilized to define automatically the tomographic slices for enhanced visualization and quantification of the clinical data. The methodology is broadly composed of two main steps: (1) volume segmentation of cardiac SPECT data; and (2) topological goniometry, a novel approach incorporating volume visualization and computer graphics ideas to determine the overall shape of 3-D objects. The outcome of the algorithm is a 3-D curve representing the overall pose of the LV long-axis. Experimental results on both phantom and clinical data (50 technetium-99m and 74 thallium-201) are presented. An interactive graphical interface to visualize the volume (3-D) data, the left ventricle, and its pose is an integral part of the overall methodology. This technique is completely data driven and expeditious, making it viable for routine clinical use.

Visualization of multimodality cardiac imagery.

A large number of clinically important and medically difficult decisions in diagnostic radiology involve interpreting the information derived from multiple imaging modalities. This is especially true in the assessment of heart disease, wherein at least two types of image information are generally required prior to deciding on the course of action: structural information describing coronary vessel anatomy and functional information related to heart muscle physiology. This paper will present and discuss the methods and results associated with a research program aimed at quantifying and visualizing the unified anatomic and physiologic information obtained from these complementary imaging modalities. The discussions will emphasize the reconstruction, processing, and visualization of three-dimensional cardiovascular structure, including the procedures and results obtained from phantom and patient studies.