Attenuation and scatter compensation in myocardial perfusion SPECT.

Nonuniform attenuation, Compton scatter, and limited, spatially varying resolution degrade both the qualitative and quantitative nature of myocardial perfusion SPECT. Physicians must recognize and understand the effects of these factors on myocardial perfusion SPECT for optimal interpretation and use of this important imaging technique. Recent developments in the design and implementation of compensation algorithms and transmission-based imaging promise to provide clinically realistic solutions to these effects and provide the framework for truly quantitative imaging. This achievement should improve the diagnostic accuracy and cost-effectiveness of myocardial perfusion SPECT.

Outcome of medical versus invasive treatment strategies for non-high-risk ischemic heart disease.

The purpose of this study was to evaluate the outcomes of medical management compared with invasive management for patients with mild or moderate ischemia (non-high-risk) on stress tomographic myocardial perfusion scintigraphy. Of the 1,352 non-high-risk patients, 116 (9%) subsequently were referred for coronary angiography within the first 30 days after the scan; 99 (85%) of this group also underwent early revascularization procedures. The remaining 1,236 patients (91%) with non-high-risk ischemia did not undergo early invasive management. Unadjusted actuarial 3-year rate of cardiac death or nonfatal infarction was significantly better estimated survival in the medically managed group (2%) compared with the invasively managed group (22%), p = 0.0001. Subsequent coronary revascularization procedures during 3-year follow-up were less frequent in the medically managed group (4%) than in the invasively managed group (42%), p = 0.0001. A multivariable analysis identified invasive management strategy (p = 0.0001) as the only correlate of cardiac events during follow-up. In summary, this study showed that patients with non-high-risk ischemia on stress perfusion imaging can be treated safely with a conservative medical management strategy.

Quantitative SPECT imaging: a review and recommendations by the Focus Committee of the Society of Nuclear Medicine Computer and Instrumentation Council.

This article is a review of the physics principles, instrumentation and reconstruction methods behind SPECT imaging. Particular attention is paid to the mechanisms that can significantly affect the accuracy of a SPECT image. We describe instrumentation advances and reconstruction methods used to correct images to improve image quality and produce quantitative images. The clinical importance of improved image quality and quantitation are also reviewed.

Hemorrhagic complications of severe pancreatitis.

Massive hemorrhage associated with pancreatitis is a rare but frequently lethal complication. Fifteen patients with this complication are presented. Bleeding occurred in four patients with necrotizing pancreatitis, in three patients with pancreatic abscesses, in seven patients with pseudocysts, and in one patient with chronic relapsing pancreatitis following longitudinal pancreaticojejunostomy. The initial presentation of hemorrhage was gastrointestinal in eight patients and retroperitoneal or intraperitoneal in seven. Abdominal pain with associated nausea and vomiting was present in all patients on admission. Duration of symptoms prior to hospitalization averaged 6 days. During hospitalization the 15 patients received a total of 512 units of blood for transfusions ranging from 8 to 177 units. Admission amylase values were of no benefit in assessing severity of the disease, but application of Ranson's criteria accurately predicted both severity and prognosis. The common denominator in all cases of bleeding appeared to be the presence of an overwhelming or continuing inflammatory process with necrosis and erosion of adjacent vascular and visceral structures. The overall mortality rate in the series was 53.3%. Those patients with hemorrhage associated with pseudocyst formation had the highest survival rates, whereas those with necrotizing pancreatitis and hemorrhage had an extremely poor response to aggressive medical and/or surgical management.

Successful embolization of the dorsal pancreatic artery to control massive upper gastrointestinal hemorrhage.

Selective arterial embolization is an established technique to control gastrointestinal bleeding in patients who are poor surgical risks and in whom bleeding is uncontrolled by other methods. This article describes the control of upper gastrointestinal bleeding by subselective embolization of a bleeding branch of the dorsal pancreatic artery in a patient with severe pancreatitis. This is the first recorded successful embolization of the dorsal pancreatic artery to control hemorrhage.