Robert W. Parkey

Tomographic gated blood pool radionuclide ventriculography: analysis of wall motion and left ventricular volumes in patients with coronary artery disease.

The use of planar radionuclide ventriculography to evaluate global and segmental ventricular function is limited by the superimposition of structures in some projections and the gross segmental resolution of the planar technique. Preliminary reports have suggested the feasibility of tomographic gated radionuclide ventriculography with rotating detector systems. This study tested the hypotheses that 1) tomographic radionuclide ventriculography detects segmental dysfunction at rest not identified with multiview planar studies and single plane contrast ventriculography, and 2) ventricular volumes and ejection fraction calculated from these studies provide data similar to those obtained with angiography and planar radionuclide ventriculography. Gated blood pool tomograms were acquired over 180 degrees at 15 frames per cardiac cycle during the initial 90% of the cardiac cycle. Compared with the multiview planar technique tomographic ventriculography showed an increased sensitivity for detecting left ventricular segments with significant coronary artery stenosis (97 versus 74%, p less than 0.025) without any loss in specificity. Compared with both planar radionuclide and contrast ventriculography, tomographic radionuclide ventriculography also detected more noninfarcted left ventricular segments supplied by stenosed coronary arteries (81 versus 39 and 32%, respectively, p less than 0.01). Tomographic radionuclide ventriculographic measurements of left ventricular volumes and ejection fraction showed close correlations with angiographic and planar radionuclide determinations. Gated blood pool tomography is a sensitive method for the evaluation of segmental wall motion and an accurate method for the measurement of global left ventricular volumes and ejection fraction.

Early positive technetium-99m stannous pyrophosphate images as a marker of reperfusion after thrombolytic therapy for acute myocardial infarction

Fourteen patients with transmural acute myocardial infarction (AMI) were treated with intravenous streptokinase a mean of 4 +/- 1 hours after chest pain and underwent technetium-99m stannous pyrophosphate (Tc-99m-PPi) imaging 7 +/- 2 hours after the onset of chest pain. The early Tc-99m-PPi images were obtained to test the hypothesis that an early, strongly abnormal Tc-99m-PPi image suggests reperfusion. Eleven of 14 patients had early peaking (within 16 hours) serum creatine kinase isoenzyme levels (CK-B) at a mean of 11 +/- 3 hours. Ten of 14 patients had 3+ or 4+ acute Tc-99m-PPi images. Eight of 11 patients had patent infarct-related vessels at cardiac catheterization 15 days after AMI. One patient who had both an early positive Tc-99m-PPi image and CK-B peak level had an occluded infarct-related artery at catheterization. Acute left ventricular (LV) ejection fraction (EF) by radionuclide ventriculography was compared with LVEF on day 15, and improved from 0.37 +/- 0.13 to 0.50 +/- 0.16 (p = 0.004) in the 10 patients with strongly positive acute Tc-99m-PPi images. LVEF also improved from 0.37 +/- 0.12 to 0.49 +/- 0.15 (p = 0.003) in the 11 patients with early peaking serum CK-B values. Three patients without evidence of reperfusion failed to improve the LVEF from the initial value to the one obtained at hospital discharge. Six control patients had acute Tc-99m-PPi images 10 +/- 2 hours after chest pain; none had strongly positive acute Tc-99m-PPi images, and the mean time to peak CK-B was 19 +/- 5 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of computed tomography for a three-dimensional treatment planning system

Computed tomography (CT) can generate a set of serial contiguous slices which form a volume of medical image data. We have developed new techniques for creating computer synthesized 3-D images directly from a volume encoded as a three-dimensional array. The operator can place the eye anywhere in object space to selectively view a portion of the volume from any angle. A set of volume processing tools have been recently developed to allow interactive manipulation of image data within the volume. These tools allow the system to be used for surgical planning, and craniofacial implant design.

Role of cardiovascular nuclear medicine in evaluating trauma and the postoperative patient

In the patient with cardiac trauma, radionuclide imaging may provide important information about cardiac mechanical function, vascular anatomy and integrity, myocardial perfusion, and myocardial metabolism. Studies require only minimal patient cooperation, can be performed relatively rapidly and often at the bedside, and may be repeated at frequent intervals for serial evaluations. These studies provide valuable adjunctive knowledge when selected and interpreted with knowledge of the mechanism of injury, timing of the examination relative to the time of injury, and most likely differential diagnoses.

Intestinal duplication detected with technetium-99m sodium pertechnetate imaging of the abdomen

A 6-year-old male child presented with melena starting two days prior to admission. On the day of admission the patient complained of intermittent epigastric pain. The patient had a past history of one episode of rectal bleeding at age 18 months. Physical examination on admission revealed a heart rate of 132/rain, respiratory rate of 24/min, blood pressure 94/50, and extreme pallor. He was unable to hold himself erect. His abdominal exam was unremarkable with exception of increased bowel sounds. Rectal examination was normal, and the stool was melanotic. Nasogastric aspiration was negative for blood. Chest x-ray and flat plate of the abdomen were normal. Admission laboratory examination revealed: WBC 13,700, hemoglobin 5.6 g/100 ml, hematocrit 15.9%, MCV 85/xm 3, reticulocytes 4.9%. Barium swallow and upper-gastrointestinal series were normal. Small-bowel follow-through revealed a mucosal abnormality with trapping of barium between three large folds (Figure 1) in the right lower quadrant. Barium enema was normal. Technetium scan of the abdomen was performed, and it revealed a consistent large area of increased uptake in the right lower quadrant (Figure 2). The patient was taken to surgery, and an intestinal duplication was found in the mesentery, 3 ft from the ileocecal valve.

Measurement of Myocardial Infarct Size Using Nuclear Cardiology Methods

The extent of myocardial infarction is an important predictor of patient course during the initial several months following acute myocardial infarction. Recently, several radionuclide methods have been developed that may provide insight into the extent of myocardial infarction. This review describes these methods, indicates their usefulness and limitations, and suggests a strategy for further development in the future.

Technetium-99m-Pyrophosphate Myocardial Imaging in Acute Myocardial Infarction

The recognition of acute myocardial infarcts is not always easily accomplished. Infarct recognition is especially difficult using electrocardiography in individuals who had previous myocardial infarcts, those with left bundle branch block, those who have been cardioverted, and those with acute non-transmural (subendocardial) myocardial infarcts. Even the most sophisticated enzymatic techniques presently available have certain limitations in identifying the presence of absence of acute myocardial infarcts in patients including: (1) there is a temporal dependency in the ability of various enzyme markers to detect acute myocardial infarcts, and (2) certain clinical settings preclude using traditional enzyme techniques (including creatine kinase — MB isoenzyme) for infarct recognition and to be emphasized in this regard is the perioperative and postoperative setting after coronary artery revascularization. Therefore, it is important to have additional relatively noninvasive means that allow infarct detection, localization and provide some estimate of the size of the lesion.

Mechanisms of Technetium-99m-Pyrophosphate Accumulation in Damaged Myocardium

The purpose of this chapter is to summarize the available information concerning the pathophysiological basis for the use of the “hot spot” myocardial imaging technique, 99mTc stannous pyrophosphate in the detection of irreversibly damaged myocardial tissue, including acute myocardial infarcts. 99mTc-pyrophosphate is classified as a “hot spot” imaging technique since it concentrates in acutely infarcted myocardium. Table 3-1 identifies other “hot spot” imaging techniques that also allow the recognition of acute myocardial necrosis. This chapter will concentrate on the use of 99mTc-pyrophosphate as an “infarct avid” or “hot spot” agent to detect acute myocardial infarcts.

Technetium-99m-Pyrophosphate Myocardial Imaging in Patients with Atypical Chest Pain

Technetium-99m-pyrophosphate myocardial scintigrams may be utilized to help exclude the presence of acute myocardial infarcts in patients with atypical chest pain that are admitted to the coronary care unit. Our previous clinicopathologic correlates have suggested that 99mTc-pyrophosphate myocardial scintigrams are capable of identifying acute myocardial necrosis with 89% sensitivity and high specificity; this scintigraphic approach has an even higher sensitivity (one approaching 100%) in the identification of acute myocardial necrosis amounting to 3 g or more in weight when serial myocardial imaging is utilized and imaging is performed within the proper time frame (Table 13-1) [1–3]. When two 99mTc-pyrophosphate myocardial scintigrams are obtained in the first 24 hr to 5 days after acute myocardial infarction, one may be confident that serial negative 99mTc-pyrophosphate myocardial scintigrams exclude acute myocardial necrosis amounting to 3 g or more tissue with better than 95% sensitivity (Table 13-1)[1,2]. This, of course, requires optimal imaging technique and imaging within the appropriate time periods after the onset of symptoms (chapters 3 and 7) and some experience so that one may properly interpret the 99mTc-pyrophosphate myocardial scintigrams.

Technetium-99m-Pyrophosphate Myocardial Imaging in Unstable Angina

Technetium-99m-pyrophosphate myocardial scintigrams may be abnormal in patients with unstable angina pectoris even if serum enzymes are normal and the electrocardiogram is either normal or nonspecifically abnormal and demonstrates ST-T wave changes [1–3]. Abnormal 99mTc-pyrophosphate scintigrams in these patients often demonstrate faint (“2+”) and poorly localized increased 99mTc-pyrophosphate uptake (Figures 11-1, 11-2 and 11-3).