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Nuclear medicine practice and work force demographics reflect the historically diverse evolution of this specialty. The most pressing problem for nuclear medicine is a projected shortage of fully trained physicians due to practitioner retirement that is unmatched by residency program output. During the past decade the number of 2-year nuclear medicine residency programs (average of 90) and the total number of residents (average of 191 in both years) have remained remarkably stable. In contrast, the number of 1-year nuclear radiology residency programs, available positions, and residents have declined significantly. A similar decline is seen in radiologists obtaining full nuclear medicine training and American Board of Nuclear Medicine (ABNM) board certification. This void has been filled by nonradiologist trainees who only seek certification by ABNM. Perhaps such shifts in resident profile are an early indicator that the United States is evolving toward practice models in which nuclear medicine is provided by fully trained, full-time physicians, similar to the European work force model. The recent Society of Nuclear Medicine survey of 10,446 physicians who practice nuclear medicine shows a current practice pattern in the United States that is distinctly different from that in Europe. The vast majority of those surveyed practice part time. Only 7% of all physicians who practice nuclear medicine do so full time, (ie more than 90% of the time), but they account for as much full-time employee (FTE) work load as 70% of all part-time physicians. Although the number of radiologists entering nuclear medicine is declining, 51% of total FTE work load is still done by radiologists with only American Board of Radiology certification. Physicians certified by ABNM represent 42% of all FTE work load. Cardiologists certified by American Board of Internal Medicine-Cardiovascular Specialization account for approximately 4% of nuclear medicine (15% of total cardiovascular nuclear medicine) FTE work load. Work force shortage of nuclear medicine technologists remains a chronic problem in spite of extensive study: however, recent predictions suggest some improvement in the future. Solutions to work force problems facing nuclear medicine will require ongoing data surveys, aggressive recruitment of trainees, expansion of training positions, and socioeconomic initiatives that promote desirable future practice models.

Purpose To evaluate the utility of technetium-99m red blood cell (Tc-99m RBC) scintigraphy in the diagnosis of active hemorrhage into large intra-abdominal hematomas before arteriography. Methods This retrospective case series describes four patients (1 man and 3 women) with large abdominal wall and retroperitoneal hematomas confirmed by computed tomography who underwent Tc-99m RBC scintigraphy before angiography. Arterial transcatheter embolization was performed if active hemorrhage was found. Results Three of the patients had positive findings on Tc-99m RBC scans, which showed spreading of the labeled erythrocytes into the hematoma space. Positive scintigraphy was diagnostic for active hemorrhage and helped localize the bleeding sites. Angiography confirmed the diagnosis in all patients with positive scintigraphy and ruled out active bleeding in the patient with a negative Tc-99m-labeled RBC scan. Conclusion Tc-99m RBC scintigraphy appears to be sensitive and accurate in detecting active hemorrhage into intra-abdominal hematomas.

Hypothesis Cinematic technetium Tc 99m red blood cell ( 99m Tc-RBC) scans, in which real-time scanning is performed and analyzed, can accurately localize gastrointestinal bleeding and thus direct selective surgical intervention. Design Retrospective medical record review with historical controls. Setting Large, university-affiliated public hospital in urban setting. Patients Twenty-six patients presenting with upper and lower gastrointestinal hemorrhage who underwent cinematic 99m Tc-RBC scan examinations between 1990 and 1997 and required surgical intervention to control the bleeding. Interventions All patients with gastrointestinal bleeding underwent open surgical procedures to provide cessation of bleeding and resection of appropriate abnormalities. Main Outcome Measures Patient outcome was based on correlation between preoperative RBC scans and intraoperative findings, surgical pathology, and postoperative clinical course. Results Twenty-five (96%) of 26 scans were interpreted as positive for gastrointestinal bleeding. In 22 of these 25 scans, the site of bleeding was correctly identified for a sensitivity of 88%. One or more additional diagnostic tests were performed on 19 (73%) of 26 patients, and included angiography and flexible endoscopy. The most common operation performed to control bleeding was a hemicolectomy (14/26). Diverticulosis was the most prevalent diagnosis (46%). Two patients (8%) experienced rebleeding after operation. The overall mortality rate was 19% (5/26). Conclusions Cinematic 99m Tc-RBC scintigraphy is a sensitive, noninvasive alternative to mesenteric angiography for accurately localizing the site of gastrointestinal hemorrhages. As such, this technique can be reliably used to direct selective surgical intervention.

The authors report a successful Meckel's scan performed 26 hours after a labeled RBC study using a commercial in-vitro labeling kit, UltraTag (Mallinckrodt Medical, Inc., St. Louis, MO). No abnormal alteration of Tc-99m distribution was observed as would be seen if an in-vivo RBC labeling technique was used. This case demonstrates that it is feasible to perform an in-vitro labeled RBC study for acute gastrointestinal bleeding in pediatric patients and to follow-up with a Meckel's scan if it is necessary for diagnostic confirmation.

Many clinical cases of cocaine-induced myocardial infarction have been reported in the literature. Of the reported cases, patients tend to be young (in the third decade of life), chronic abusers with myocardial infarction typically involving the anterior left ventricular wall. This case report demonstrates the usefulness of two-phase (symptomatic and asymptomatic) Tc-99m sestamibi myocardial imaging at rest for definitive diagnosis of cocaine-induced myocardial ischemia and infarction.

Nuclear medicine procedures can be used effectively to assess abnormalities of the chest following thoracic or nonthoracic trauma. The most significant applications include studies of ventilation and perfusion in blunt chest trauma and burns, thromboembolism, and fat embolism syndrome. The evaluation of subtle fractures, pleural and pericardial fluid collections, mediastinal masses, and radiation damage by radionuclidic techniques is also useful. Considerable research will be required to ultimately define the role of nuclear medical procedures in the diagnosis of thoracic abnormalities in trauma.

Liver scans, biopsies, and function studies were reviewed in 63 cancer patients and correlated with autopsy material to determine the value of the liver scan in such patients. The scan is abnormal in 96% of patients with autopsy-confirmed hepatic disease, but the scan pattern is of little assistance in differentiating tumor from nontumor pathology. Liver function studies are equally nonspecific and even less sensitive than the scan. Percutaneous biopsy, while diagnostic when positive, is insensitive, showing false-negative results in up to 40% of cases. The liver scan, as the most sensitive indicator of liver disease, may be most valuable when normal, reflecting a better prognosis and aiding in the determination of treatment. When the liver scan is abnormal, more specific tests must be employed. A method of approach is suggested.

The case of a 22 year old Negro man with sarcoidosis proved by biopsy to involve lung, liver and myocardium is reported. The electrocardiogram showed typical changes of an anterolateral wall myocardial infarction, and the patient had multiform premature ventricular contractions and episodes of ventricular tachycardia which were unresponsive to treatment with steroids and currently available antiarrhythmic agents. Aneurysm of the left ventricular apex—the size of a tennis ball—was demonstrated by angiocardiography, and surgical resection provided dramatic improvement of the ventricular arrhythmias. This is the third reported case of ventricular aneurysm due to sarcoid, and the first case to be diagnosed clinically and treated successfully by surgical resection at open heart surgery. Ventricular aneurysm, regardless of origin, may present with refractory ventricular tachycardia, which can be successfully treated by surgical excision of the aneurysm.

The effect of a standardized meal on left ventricular (LV) ejection fraction (EF) was determined by equilibrium radionuclide angiography in 16 patients with stable congestive heart failure but without pulmonary or valvular heart disease. LVEF was determined in the fasting state and 15, 30, and 45 minutes after a meal. Patients with moderately depressed fasting LVEF (30 to 50%), Group I, had a mean increase of 6.9 +/- 2.9% (p less than 0.005) in the LVEF at 45 minutes after the meal. Patients with severely depressed fasting LVEF (less than 30%), Group II, had no change after the meal. It is concluded that significant increases in LVEF may occur after meals in patients with moderate but not severe left ventricular dysfunction. Equilibrium radionuclide angiography studies that are not standardized for patients' mealtimes may introduce an important unmeasured variable that will affect the validity of data in serial studies of left ventricular function.

Following receipt of fission product 99mTc-generators, results of radionuclide purity analysis, performed within 30 min after the first elution, demonstrated detectable levels of a contaminate radionuclide not previously reported. Gamma spectroscopy and half-life determinations confirmed the presence of 82Br. Bromine-82 activity, in eluates from the first elution of 30 generators, received weekly during a 7-month period, ranged from 0.22 microCi (8.235 kBq) to 0.67 microCi (24.68 kBq) per eluate. The ratio of 99Mo to 99mTc ranged from 0.13 nCi to 0.39 nCi per mCi 99mTc. The presence of 82Br in 99mTc-generator eluate resulted in falsely elevated 99Mo assay determinations using whole vial 99Mo assay procedures. For every 0.1 microCi 82Br present in 99mTc eluate the 99Mo assay results were elevated by 1 microCi. Gamma spectroscopy of eluates from additional elutions of these generators failed to detect the presence of 82Br demonstrating the displacement of monovalent bromine anions from the alumina column during the first elution.

Nuclear medicine imaging procedures can play a significant role in evaluating the pulmonary complications that are seen in trauma patients. A quantitative method for measuring increased pulmonary capillary permeability that uses Tc-99m HSA allows early diagnosis of acute respiratory distress syndrome (ARDS) and accurately differentiates this condition from pneumonia or cardiogenic pulmonary edema. This technique may be of great value in following the response to therapy. The use of 133 Xe to diagnose inhalation injury remains an important diagnostic tool, particularly at hospitals with specialized burn units. Regional decreases in ventilationperfusion images reliably localize aspirated foreign bodies. Radionuclide techniques that are used to demonstrate gastropulmonary aspiration remain controversial and require further clinical validation. Pulmonary perfusion imaging, although nonspecific, may provide the earliest clue for correct diagnosis of fat embolism, air embolism, contusion, or laceration. Furthermore, the possibility of perfusion abnormality due to these uncommon conditions must be remembered whenever trauma patients are evaluated for pulmonary thromboembolism with scintigraphy. Occasionally, liver or spleen scintigraphy may be the most appropriate procedure when penetrating chest trauma also involves these subdiaphragmatic organs.

Nuclear medicine imaging techniques are being more widely applied to study a variety of lung injuries. Ventilation and perfusion imaging is often superior to other roentgenographic techniques for establishing the diagnosis and demonstrating the extent of such injuries. At several large burn centers, the Xe-133 washout technique has become the cornerstone for diagnosing early inhalation injury. The overall accuracy of this procedure is 92%. Regional decreases in ventilation and perfusion can reliably localize aspirated radiolucent foreign bodies. Disproportionate perfusion changes are often the earliest indicator of radiation pneumonitis and other forms of vascular injury. Other types of injury, such as gastropulmonary aspiration, blunt trauma, and near-drowning, require further evaluation before the ultimate role of nuclear imaging is defined. An imaging technique to assess capillary permeability in the adult respiratory distress syndrome would be of great clinical benefits.

This case of bronchial adenoma is used as a clinical model demonstrating absence of pulmonary perfusion by 131I-MAA scanning secondary to bronchial obstruction. Radiographic and radionuclide studies are correlated and other causes of pulmonary hypoperfusion discussed. The literature and related cases are reviewed.

• Scintigraphy with RBCs labeled with technetium Tc 99m sodium pertechnetate effectively located the source of hemorrhage in a patient receiving long-term anticoagulant therapy. (The patient was initially seen with a large hematoma on the flank.) More important, the procedure was used to monitor activity in this otherwise-occult bleeding site. Scintigraphic studies may be useful in the management of these difficult clinical problems. (Arch Intern Med1983;143:1027-1028)

• Seventy-six patients clinically suspected of having lower gastrointestinal bleeding were studied by scintigraphy utilizing red blood cells labeled in vitro with technetium Tc 99m. Sixteen patients required emergency surgery; bleeding was accurately localized in 15 (94%). One patient (6%) had a normal scan. A 20-month mean follow-up of the 16 patients showed no recurrent bleeding. Of 60 patients not requiring emergency surgery, bleeding was localized in 11, but the bleeding ceased. Forty-nine of the 60 patients had normal scans and had no further hemorrhaging during hospitalization. A 21-month mean follow-up of 38 of the 49 patients showed no further bleeding episodes or surgical procedures in 29 patients; however, eight patients required surgical procedures, including seven for gastrointestinal malignancies. Scanning of red blood cells labeled in vitro with99mTc is accurate and efficacious in localization of bleeding sites that require emergency surgery for lower gastrointestinal hemorrhage. (Arch Surg1985;120:621-624)

Patients with liver glucose-6-phosphatase deficiency are at risk for developing hepatomata in adult life. Investigations during adolescence and early adult life indicate that these patients may have discrete filling defects as well as depressed isotope uptake on liver scan with technitium sulfur colloid but only mild abnormalities of liver related serum chemistries (Table). On hepatic anglograms in two patients, the filling defects appeared as vascular masses consistent with primary or metastatic malignancy; biopsy showed increased glycogen content but no changes of malignancy. Other storage disorders affecting the liver which have been investigated to date have not shown similar abnormalities on liver scan, nor do they have the tendency for developing malignancy in later life.

Sixteen patients clinically suspected of having gastrointestinal hemorrhage were studied by abdominal scintigraphy with RBCs labeled in vitro with technetium Tc 99m. Ten of 11 actively bleeding patients had positive scintigrams, with bleeding localized to the duodenum in one, ascending colon in five, sigmoid colon in six, and rectosigmoid colon in one. Scintigraphic findings were corroborated by clinical, endoscopic, arteriographic, and surgical findings. Retention of this blood-pool radiotracer in the vascular compartment allows noninvasive diagnosis of acute, as well as slow or intermittent, bleeding for up to 24 hours after intravenous administration. (JAMA1982;247:789-792)