David A. Turner

Matching of tomographic slices for interpolation

An automatic method that can transform a sequence of tomographic image slices into an isotropic volume data set is described. In this method, correspondence is established between points in consecutive slices, and then this correspondence is used to estimate data between the slices by linear interpolation. The method takes advantage of the fact that consecutive slices have small geometric differences, and carries out the search in predicted small neighborhoods. Only points with high gradient magnitudes are used in the search process to increase the reliability of the correspondences. Mismatches that occur are detected and corrected using the continuity constraint in the correspondences. Experimental results showing the matching and interpolation of magnetic resonance slices and computed tomography slices are presented.

Segmentation of cardiac cine MR images for extraction of right and left ventricular chambers

A two-stage algorithm for extraction of the ventricular chambers (endocardial surfaces) in flow-enhanced magnetic resonance images is described. In the first stage, the approximate locations and sizes of the endocardial surfaces are determined by intensity thresholding. In the second stage, points on each approximated surface are repositioned to nearest locally maximum gradient magnitude points and a generalized cylinder is fitted to them. Examples of ventricular chambers in cine MR images determined by this algorithm are presented.

Gallium-67 imaging in the management of Hodgkin's disease and other malignant lymphomas

Gallium-67 imaging is useful in the management of patients with malignant lymphoma, despite its obvious limitations. Data currently in the literature regarding the detectability of sites of lymphoma by 67Ga imaging should be regarded as representing the minimum that can be expected from the method, since all reported series are based on outmoded imaging techniques. The detectability of disease sites appears to vary with tumor histology and anatomic location. Gallium-67 imaging is most useful in following patients after treatment. However, it may justifiably play an important role in the initial staging of lymphoma if the prior probability of disease in the abdomen is low. Lymphoma in abdominal lymph node sites is at least as detectable by 67Ga imaging as by lymphangiography.

The Use of 67Ga Scanning in the Staging of Hodgkin's Disease1

Gallium-67 whole body scanning has been used to determine the extent of Hodgkins disease in 20 patients. Disease sites have been confirmed by pathological examination of tissue obtained at laparotomy or local excision biopsy, as well as chest radiographs and physical examination of superficial lymph node groups. Of 29 disease sites, 23 (79%) were correctly identified by 67Ga scanning. Six areas were thought to be involved by disease on the basis of the scan but were found to be uninvolved at surgery. Gallium-67 scanning is recommended as a useful supplement in the staging of Hodgkins disease.

The use of 67 Ga scanning in the staging of Hodgkin's disease.

Gallium-67 whole body scanning has been used to determine the extent of Hodgkins disease in 20 patients. Disease sites have been confirmed by pathological examination of tissue obtained at laparotomy or local excision biopsy, as well as chest radiographs and physical examination of superficial lymph node groups. Of 29 disease sites, 23 (79%) were correctly identified by 67Ga scanning. Six areas were thought to be involved by disease on the basis of the scan but were found to be uninvolved at surgery. Gallium-67 scanning is recommended as a useful supplement in the staging of Hodgkins disease.

Quantitative sacroiliac scintigraphy. The effect of method of selection of region of interest

Various authors have advocated quantitative methods of evaluating bone scintigrams to detect sacroiliitis, while others have not found them useful. Many explanations for this disagreement have been offered, including differences in the method of case selection, ethnicity, gender, and previous drug therapy. It would appear that one of the most important impediments to consistent results is the variability of selecting sacroiliac (SI) joint and reference regions of interest (ROIs). The effect of ROI selection would seem particularly important because of the normal variability of radioactivity within the reference regions that have been used (sacrum, spine, iliac wing) and the inhomogeneity of activity in the SI joints. We have investigated the effect of ROI selection, using five different methods representative of, though not necessarily identical to, those found in the literature. Each method produced unique mean indices that were different for patients with ankylosing spondylitis (AS) and controls. The method of Ayres (19) proved superior (largest mean difference, smallest variance), but none worked well as a diagnostic tool because of substantial overlap of the distributions of indices of patient and control groups. We conclude that ROI selection is important in determining results, and quantitative scintigraphic methods in general are not effective tools for diagnosing AS. Among the possible factors limiting success, difficulty in selecting a stable reference area seems of particular importance.

Fusion of short-axis and long-axis cardiac MR images.

A method for fusion of the short-axis and long-axis cardiac MR images into an isotropic volume image is introduced. A volume image obtained by this method contains the left ventricular (LV) cavity in one piece, facilitating measurement of its shape and volume. The main goal in this image fusion is to reconstruct the LV cavity in volume form and in high resolution. The accuracy of the method is measured using a synthetic image, and examples of image fusion using real images are presented.

Bone Scintigram in Cardiac Amyloidosis: A Case Report

Intense, diffuse localization of Tc-99m-pyrophosphate was demonstrated in the right and left ventricles of a patient with biopsy-proved amyloidosis and severe congestive heart failure. This finding is strong presumptive evidence of myocardial infiltration by amyloid in the presence of biopsy-proven amyloidosis elsewhere in the body.

Nuclear magnetic resonance in oncology.

The application of nuclear magnetic resonance (NMR) techniques to the diagnosis of cancer was first explored by Damadian, who proposed that benign and malignant tissues could be differentiated on the basis of characteristic differences in spin-lattice and spin-spin relaxation times (T1 and T2) as determined in vitro with NMR spectrometers. Damadians thesis was very controversial and never gained widespread acceptance. Not all investigators were able to confirm his findings. Moreover, it was improbable that NMR would ever play an important role in the diagnosis of malignancy as long as biopsy was necessary to obtain material for analysis. However, the potential usefulness of NMR in oncology was enhanced considerably by the work of Lauterbur, who showed that NMR signals could be spatially encoded to produce images of the examined object. NMR imaging has made feasible the measurement of the T1 and T2 of lesions without biopsy. Unfortunately, initial efforts at characterizing tissues by in vivo determination of proton relaxation times have yielded disappointing results. Nonetheless, NMR imaging will be a powerful tool for evaluating patients with malignant disease because of the unique anatomic information it can provide without exposure of the patient to ionizing radiation. In vivo NMR spectroscopy of 31P and other sensitive nuclei may add a new dimension to clinical and experimental oncology.

Respiratory gating in magnetic resonance imaging: Improved image quality over non-gated images for equal scan time

Magnetic resonance image quality is adversely affected by respiratory (RESP) motion during the scan. Respiratory gating improves magnetic resonance image (MRI) quality and removes artifacts, but has not been widely used, as RESP gating increases scan time. Our RESP-gating device was used to study scan time versus improvement in image quality using various gating modes; with and without combined electrocardiographic (ECG) gating. When RESP scans were acquired for the same time as non-gated scans, by using a wide RESP-gating window bracketing end expiration and a reduced number of pulse sequence repetitions, substantial improvement in image quality (over non-gated scans) resulted, despite the inferior statistical content of the acquisition.