Segmental wall motion abnormalities in dilated cardiomyopathy: a common finding and good prognostic sign.

Fifty patients with idiopathic dilated cardiomyopathy were separated into two groups based on the presence of segmental or diffuse left ventricular wall motion abnormalities by radionuclide ventriculography. Investigation included a history and physical examination, electrocardiogram, chest X-ray film, M-mode echocardiogram, coronary angiogram and right ventricular endomyocardial biopsy. Patients with histologic evidence of myocarditis were excluded. Sixty-four percent of the patients had segmental and 36% had diffuse wall motion abnormalities. The group with segmental abnormalities showed significant differences in age (52.5 +/- 10.7 versus 37.8 +/- 14.6 years, p less than 0.001), New York Heart Association functional class III to IV (56 versus 89%, p less than 0.01), pulmonary capillary wedge pressure (14 +/- 9 versus 26 +/- 9 mm Hg, p less than 0.001), left ventricular end-diastolic dimension measured on echocardiogram (67 +/- 8 versus 77 +/- 11 mm, p less than 0.001), cardiac index (2.6 +/- 0.6 versus 2.0 +/- 0.5 liters/min per m2, p less than 0.01) and ejection fraction by radionuclide ventriculography (20 +/- 7 versus 13 +/- 5%, p less than 0.001). Patients with diffuse wall motion abnormalities had poorer histologic findings based on myocardial cell hypertrophy and nuclear changes (p less than 0.01) and a higher short-term mortality with a 1 year survival rate of 50% compared with 90% in patients with segmental wall motion abnormalities by life-table analysis (p less than 0.05). When data were reanalyzed excluding those patients with complete left bundle branch block, no significant change in any variable was detected. Segmental wall motion abnormalities, even when left bundle branch block is excluded, are common in dilated cardiomyopathy in the absence of coronary artery disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Seven-pinhole multigated tomography and its application to blood-pool imaging: technical parameters.

The application of seven-pinhole tomography has been predominantly to thallium-201 myocardial imaging. In view of the stationary nature of the collimator, with all views accumulating simultaneously, seven-pinhole tomography can be adapted to dynamic cardiac imaging, namely, multigated blood-pool imaging. Existing reconstruction software was modified to process the gated blood-pool data. The performance parameters of the seven-pinhole system were investigated at Tc-99m energy. This work provides an additional understanding of the seven-pinhole system as well as its potential application to abnormalities of ventricular wall motion or the quantitation of other cardiac parameters from reconstructed data.

The sources of overestimation in the quantification by SPECT of uptakes in a myocardial phantom: concise communication.

A single photon emission computerized tomographic (SPECT) system's overestimation of the tracer concentration in a myocardial perfusion defect was examined by physical phantom studies. An empirical attenuation correction was used to isolate the problem of overestimation from imperfect attenuation correction. The overestimation of defect concentration in our SPECT system was found to come from three sources: software error, finite spatial resolution of the system, and scattered photons generated inside the phantom. The findings confirmed the current belief that the two major problems remaining in quantification with the SPECT technique are attenuation correction and scatter correction.

A new collimator for cardiac tomography: the quadrant slant-hole collimator.

A quadrant slant-hole (QSH) collimator was constructed for myocardial perfusion tomography on a 15-inch large-field gamma camera. This system optimizes the crystal area for multiple-view photon detection while at the same time offering excellent tomographic performance. In addition to the advantages associated with parallel slant-hole collimation, this system's four orthogonal views provide a solution to the problem of patient positioning, namely, proper alignment of the long axis of the left ventricle to the camera. Rapid data acquisition, together with fast reconstruction, make the QSH system a practical approach to tomographic imaging of the myocardium.

Errors in the determination of left ventricular functional parameters.

Gated blood-pool scans of the left ventricle are routinely employed for determination of the left ventricular ejection fraction. Recently, attempts have been made to evaluate other left ventricular functional parameters. These values include peak emptying rate (PER), time to peak emptying rate (TPER), peak filling rate (PFR), and time to peak filling rate (TPFR). In studying these parameters clinically, we identified many software errors and assumptions that impact on these values. These errors may also affect the determination of left ventricular ejection fraction (EF). We conclude that before any serious investigation of left ventricular functional parameters is undertaken, a detailed evaluation and standardization of the acquisition and edge detection algorithms must be performed.

Gallium-67 citrate scanning for noninvasive detection of inflammation in pericardial diseases.

The treatment of acute nonspecific pericarditis is controversial. No study is available that confirms the efficacy of the administration of corticosteroids or nonsteroid anti-inflammatory agents in this condition. There is no reliable invasive marker for pericardial inflammation, because echocardigraphy demonstrates only the presence of fluid. In four patients with pericarditis, gallium-67 citrate scanning was performed, and the isotope was localized to the cardiac silhouette in all. In one patient with effusion the gallium scan was positive and then reverted to negative with corticosteroid therapy. In another, the gallium scan remained positive despite resolution of the pericardial effusion with corticosteroid therapy. This patient eventually required pericardial stripping. Pericardial localization of gallium was useful in detecting the cause of fever in a patient after aortocoronary bypass grafting and in detecting pericardial involvement in a patient with multisystem viral disease. Pericardial localization of gallium-67 may be diagnostically useful and may provide a proper control for the study of the efficacy of corticosteroids versus nonsteroid anti-inflammatory agents in pericarditis.

The potential impact of the resource-based relative value scale on the practice of nuclear medicine.

The Resource-Based Relative Value Scale (RBRVS) is finally here. A system designed to equate physician work across the specialties, it has its own peculiar and unique problems. Modeling of the system was based on the single physician-patient interaction; it may not work properly for laboratory specialties. There are other unique considerations concerning how the model was constructed. Although data were collected specifically for nuclear medicine, they were not used in the final computations. There is disagreement over whether those data would benefit or hurt nuclear medicine reimbursement. As presently implemented, the RBRVS poses grave dangers for the future of nuclear medicine. These dangers come not only in the professional reimbursement section of the rules but in the technical component areas as well. Estimates for reduction of income by 1996 range as high as 55% for nuclear medicine. When one factors the implementation of the RBRVS by independent insurance carriers into the equation, the entire economic future becomes muddy. A brief historical review of the RBRVS, as well as discussion of potential future implications of this type of reimbursement system, is presented. Prognostication is at least as inexact a science as reimbursement. Hopefully, the author's outlook on the future of nuclear medicine is more pessimistic than it need be.

Gallium-67 tumor scanning.

Since its introduction in 1969, 67Ga has become the most widely employed tumor-scanning agent in nuclear medicine. While 67Ga is far from being the ideal tumor-scanning agent, it remains the best available isotope for this purpose. Gallium-67-citrate has been found to be of value in the staging and reevaluation of lymphomas as well as in detecting the extent and recurrence of lung tumors, breast tumors, malignant melanomas, testicular tumors, brain tumors, and malignant lesions involving the liver. In order to obtain maximum diagnostic value from gallium scanning, several technical factors have to be taken into consideration as well as an understanding of the nature of "false-positive" scans.

Methods for detection of left ventricular edges.

The ability to accurately and reproducibly measure left ventricular performance offers significant clinical advantages in patient management. Specifically, data on wall motion of the left ventricle, the characteristics and shape of the left ventricular volume curve, and measurement of ejection fraction are the general parameters of interest evaluated. These parameters may be measured with either first-pass studies or gated equilibrium blood pool images. Either method is relatively simple, economical, and presents little risk to the patient. Over the last several years both methods have undergone considerable study, and relatively standardized techniques for the two methods exist at present. Both techniques require moderate to extensive data processing. In general, a region of interest (ROI) must be defined before further quantitative analysis is possible. There are at present multiple approaches to the establishment of an ROI for the left ventricle. The major differences between these approaches is in the algorithms used to generate the boundary of the ROI or "the edge". In order for the computer to recognize the edge of the left ventricle, objective and reproducible edge-detection processes are needed. It is the purpose of this paper to review computerized edge-detection algorithms as they apply particularly to the noisy and blurry images obtained in nuclear medicine studies.

Diagnostic value of carcinoembryonic antigen in exudative pleural effusions.

Elevated pleural fluid (PF) and plasma (PL) carcinoembryonic antigen (CEA) levels (ng/ml) were more frequently found with malignant than benign exudative effusions, but with a low true-positive rate for malignancy in general. Adenocarcinomatous effusions differed from other malignant and benign effusions in the frequency and degree of elevation of PF and PL CEA levels. A PF > 20 had a sensitivity of 91 percent and a specificity of 92 percent as a screening test for adenocarcinomatous effusions. A PF CEA > 55 or PL CEA > 10 were present only with malignancy and 98 percent specific for adenocarcinoma.

Beta blockers and the sensitivity of the thallium treadmill test.

The effect beta blockers (BB) may have on the sensitivity of the thallium treadmill test (Th-TMT) is controversial. The purpose of this study was to test the hypothesis that BB decrease the sensitivity of the Th-TMT. Two hundred three patients over a two-year period were identified who satisfied the following criteria. All had symptom-limited upright treadmill exercise tests with stress and redistribution thallium imaging, as well as coronary angiography within two months of the Th-TMT. Of 58 patients with CAD not on BB, 52 had an abnormal Th-TMT scan (sensitivity 90 percent). In comparison, the sensitivity of the Th-TMT scan in the 88 patients with CAD receiving BB was 76 percent (p less than 0.05). We conclude that BB may significantly decrease the sensitivity of the Th-TMT. Physicians should fully appreciate the higher false negative rate (24 vs 10 percent) for patients on BB and consider cautious withdrawal prior to diagnostic studies.

Indium-111-Photofrin-II scintillation scan.

Photodynamic therapy is under intense investigation as an adjuvant treatment for malignant glial tumors of the central nervous system. Photofrin-II (HpD-II) is currently the most actively investigated photosensitizing agent. A crucial issue regarding the safe and efficacious usage of HpD-II-based photodynamic therapy is the individual in vivo kinetics of tumor uptake and retention, compared with normal brain clearance. The optimal time for photoactivation of sensitized tumor must be known to ensure a high target-to-nontarget ratio, resulting in the maximal tumor destruction while preserving normal brain. Our laboratory developed a radionuclide scan based on 111indium (111In)-labeled HpD-II to evaluate HpD-II localization and clearance noninvasively within a canine model of intracerebral gliosarcoma. Synthesis of the 111In-HpD-II complex in greater than 90% yield is achieved by a simple, rapid labeling method. Radiochemical purity and stability were verified by high-performance liquid chromatography. Using the canine model of intracerebral gliosarcoma, we followed the uptake of 111In-HpD-II in tumors with serial scintillation scanning. Localization of the tumor by 111In-HpD-II has been verified by contrast-enhanced computed tomographic scan followed by gross and histological examination of the enhancing brain region. Total body biodistribution of 111In-HpD-II at various times after injection has been evaluated. The ratio of uptake in tumor compared with surrounding brain peaked at 72 hours after injection. The knowledge of regional distribution and concentration of a photosensitizing agent within a tumor mass and surrounding brain allows for the most efficacious timing and localization of a photoactivating source.

Photodynamic therapy for intracranial neoplasms: investigations of photosensitizer uptake and distribution using indium-111 Photofrin-II single photon emission computed tomography scans in humans with intracranial neoplasms.

Photodynamic therapy is being investigated as an adjuvant treatment for intracranial neoplasms. The efficacy of this therapy is based on the uptake of photosensitizer by neoplastic tissue, its clearance from surrounding brain tissue, and the timing and placement of photoactivating sources. Photofrin-II is the photosensitizer most actively being investigated. We labeled Photofrin-II with Indium-111 and studied the uptake and distribution of this agent in 20 patients with intracranial neoplasms, using single photon emission computed tomography (SPECT) with volume rendering in three dimensions. Of these patients, 16 had malignant glial tumors, 2 had metastatic deposits, 1 had a chordoma, and 1 had a meningioma. Anatomical-spatial data correlated well between the SPECT images and contrast-enhanced computed tomography or magnetic resonance images. Regions of focal uptake on SPECT images correlated with the surgical histopathological findings of the neoplasm. The kinetics of photosensitizer uptake varied according to the tumor's histological findings, the patient's use of steroids, and among patients with similar types of tumor histology. Peak ratios of target-to-nontarget tissue varied from 24 to 72 hours after injection. The study data show that, to be most effective, photodynamic therapy may need to be tailored for each patient by correlating SPECT images with anatomical data produced by computed tomography or magnetic resonance images. Photoactivating sources then can be placed, using computer-assisted stereotactics, to activate a prescribed volume of photosensitized tumor at the optimal time for treatment.

Imaging techniques for myocardial inflammation.

Dilated cardiomyopathy (DC) represents a heterogeneous group of disorders which results in morbidity and mortality in young individuals. Recent evidence suggests that a subset of these patients have histologic evidence of myocarditis which is potentially treatable with immunosuppression. The identification of myocardial inflammation may therefore lead to development of therapeutic regimens designed to treat the cause rather than the effect of the myocardial disease. Ultimately, this may result in improvement in the abysmal prognosis of DC. The currently accepted technique for identification of active myocardial inflammation is endomyocardial biopsy. This technique is not perfect, however, since pathologic standards for the diagnosis of myocarditis have not been established. Furthermore, focal inflammation may give rise to sampling error. The inflammation-avid radioisotope gallium-67 citrate has been used as an adjunct to biopsy improving the yield of myocarditis from 7 percent to 36 percent. Serial imaging correlates well to biopsy results. Future studies are designed to study the applicability of lymphocyte labelling techniques to myocardial inflammatory disease.

Abnormal ambulatory left ventricular ejection fraction in heart transplant arteriopathy.

The morbidity and mortality from heart transplantation has been reduced dramatically over the last several years. However, the long-term survival in heart transplant recipients is limited by arteriopathy in the allograft coronary arteries, the pathophysiology of which is poorly understood. The diagnosis of this arteriopathy is at present limited to cardiac catheterization. Noninvasive studies have proven to be of limited benefit in diagnosing this arteriopathy. The authors performed cardiac vest studies in nine heart transplant recipient patients. Six of the vest studies were abnormal; five of the patients had documented transplant coronary artery disease by cardiac catheterization. They found that the sensitivity and negative predictive value of the cardiac vest in identifying arteriopathy in transplant recipients was 100%. The authors propose that cardiac vest could be a sensitive, noninvasive screening test for identifying arteriopathy in heart transplant recipients.

Quality assurance in SPECT imaging.

The predominant type of single-photon emission computed tomography (SPECT) system available today is the rotating gamma camera system. These systems are complex, with many variables to control, and are prone to artifacts. To maintain optimal imaging performance, we emphasize a quality-assurance program that maintains imaging detector performance, proper mechanical alignments, periodic system calibrations, and strict adherence to imaging protocols. We urge the use of SPECT phantoms to evaluate total system performance. With SPECT phantoms, rotating camera systems with both circular and noncircular orbits can be easily evaluated. Quantitative measurements of system performance can be recorded graphically on a time chart for trend analysis, which leads to timely investigation of system failures.