Robert F. Carretta

99mTc Anti-CD 15 Monoclonal Antibody (LeuTech) Imaging Improves Diagnostic Accuracy and Clinical Management in Patients With Equivocal Presentation of Appendicitis

BackgroundAppendicitis frequently presents in an atypical fashion leading to misdiagnosis or a delay in diagnosis. This is particularly true in early cases where the patient may be erroneously discharged from an emergency department and will invariably return with perforated appendicitis. The standard of care is hospital admission for observation or early operation. Adjunctive imaging tests have been used with mixed results in this equivocal patient population. The authors studied a promising new monoclonal antibody, 99mTc-labeled anti-CD 15 (LeuTech; Palatin Technologies, Inc., Princeton, NJ), which specifically targets neutrophils and may be used for imaging appendicitis. This prospective, multicenter, open-label study evaluated the diagnostic efficacy and clinical impact of LeuTech scintigraphy for detecting appendicitis in patients with an equivocal presentation. MethodsA total of 200 patients (121 females, 79 males; age range 5–86 years; mean age 30.5 ± 16.5 years) completed the study. Management plan was formulated before and reassessed following LeuTech imaging to determine impact on management. Following intravenous injection of LeuTech, the abdomen was imaged with a standard gamma camera for 30 to 90 minutes. ResultsFifty-nine patients had a histopathologic diagnosis of acute appendicitis. LeuTech identified 53 of 59 patients with appendicitis (90% sensitivity) and was negative in 122 of 141 patients without appendicitis (87% specificity). Accuracy, positive predictive value, and negative predictive value were 88%, 74%, and 95%, respectively. Diagnostic efficacy was unchanged in a subgroup of 48 pediatric patients (5–17 years). Diagnostic images for appendicitis were achieved within 8 minutes postinjection in 50% of patients and within 47 minutes in 90% of patients. Significant shifts in patient management decisions were evident following LeuTech results. LeuTech was well tolerated with no serious adverse events reported. ConclusionLeuTech is a convenient, safe, rapid, and sensitive imaging test for diagnosis of appendicitis and favorably impacts patient management in adult and pediatric patients with equivocal signs and symptoms.

Prevention of Lower Extremity Venous Thrombosis by Early Mobilization: Confirmation in Patients with Acute Myocardial Infarction by 125I-Fibrinogen Uptake and Venography

To determine the effects of early ambulation on peripheral venous thrombosis in the coronary care unit, 29 patients with acute myocardial infarction had daily 125I-fibrinogen point counting of both legs using a standard portable technique in the first 3 to 7 days after admission. Twenty-one patients underwent early ambulation during the initial 3 days, while 8 remained at complete bed rest for 5 days. Only 2 of 21 early ambulated patients had positive fibrinogen point counts, in contrast to 5 of 8 nonambulated patients (P less than 0.01). With heart failure, only 2 of 9 ambulated patients had positive point counts, compared with 4 of 5 nonambulated patients (P less than 0.05). In 16 patients undergoing venography, point counts were confirmed in 6 positive and 10 negative findings. These results show that the high frequency of peripheral venous thrombosis in immobilized acute myocardial infarction patients, particularly those with heart failure, can be effectively reduced by early ambulation.

Procedure Guideline for Brain Perfusion SPECT Using 99m Tc Radiopharmaceuticals 3.0

1William Beaumont Hospital, Royal Oak, Michigan; 2Cedars Sinai Medical Center, Los Angeles California; 3University of Texas Southwestern Medical Center, Dallas Texas; 4College of Physicians and Surgeons of Columbia University, Harlem Hospital Affiliation, New York, New York; 5Mount Sinai Hospital, University of Toronto, Toronto, Ontario, Canada; 6Columbia-Presbyterian Medical Center, New York, New York; 7Sutter Roseville Medical Center, Roseville, California; and 8Saint Francis Medical Center, Peoria, Illinois

Upper extremity radionuclide bone imaging: The wrist and hand

Bone scintigraphy of the hands and wrists represents an important adjunct imaging technique that complements plain film radiographic examination. The use of the three-phase bone scan provides clinical information not only regarding osseous uptake but the blood flow and extravascular distribution of the radiotracer as well. Scintigraphic evaluation of the hands and wrists is employed in acute and chronic conditions. In the event of an equivocal or negative plain film, the bone scan can identify occult fractures. Of particular concern is the identification of scaphoid fractures due to the higher incidence of osteonecrosis. Work related injuries represent a significant health issue. The bone scan can be a part of the algorithm for evaluating chronic pain syndromes including reflex sympathetic dystrophy. The complimentary roles of bone scanning and imaging with gallium-67 citrate or radiolabeled leukocytes has proven useful in the evaluation of acute or chronic osteomyelitis. In addition, the diphosphonates are useful in identifying solitary and multiple primary bone tumors. In the case of primary bone tumor, thallium-201 can be used to evaluate response to therapy. Although uncommon in the hand and wrist, the bone scan can identify metastatic tumors or tumor-related conditions such as hypertrophic osteoarthropathy. Finally, bone scintigraphy may be useful in identifying location and extent in a variety of conditions such as fibrous dysplasia, histiocytosis X, and Pagets disease.

Assessment of conventional criteria for the early diagnosis of thrombophlebitis with the 125I-fibrinogen uptake test.

Analysis of 55 positive tests of a total of 300 tests by conventional criteria revealed that 125I-fibrinogen provides useful information early enough for clinical management. Of the tests which were ultimately interpreted as positive by conventional criteria, at least one was positive at 3-4 hours in 67% of the tests and 98% of the tests were positive at 24 hours after the administration of 125I-fibrinogen. A 20% difference between contralateral identical locations of the legs and a 20% difference between adjacent locations of the ipsilateral leg were found with almost equal frequency in the positive tests, whereas a 20% increase at the same location was less sensitive. The 125I-fibrogen uptake test is a simple and accurate technique for early diagnosis of active thrombophlebitis.

Correlation of bioscintigraphy, contrast venography, and iodine-125 fibrinogen uptake test

In 40 patients believed to have deep venous thrombosis, bioscintigrams performed with 1-123 fibrinogen were available for comparison with either contrast venograms or 1-125 fibrinogen uptake tests. If either contrast venography or the fibrinogen uptake test was accepted as a standard for comparison, the accuracy of bioscintigraphic imaging was 90%. Most discrepancies between the procedures could be interpreted as due to heparin treatment, although bioscintigrams often were positive in patients treated with heparin for a short interval of time. Additionally, bioscintigrams provided information to distinguish venous thrombosis from other sources for local accumulation of radioactivity. Bioscintigraphy seems to be a promising noninvasive method for the detection of deep venous thrombosis of the lower extremities.

Nuclear medicine in private practice

The private practice of nuclear medicine has evolved over the past decade. Federal and state regulatory agencies, reduction in reimbursement, and a shortage of qualified physicians and technologists will affect the practice of nuclear medicine in the 1990s and beyond. Only by being proactive and able to provide credible clinical information to our referring physicians can nuclear medicine position itself for the next decade. We must continue to educate referring physicians about the cost-effectiveness and functional and physiological nature of nuclear medicine. We need to encourage medical students and physicians in training to consider nuclear medicine as a career path, and we need to provide meaningful clinical information to our referral base. In addition to these challenges, we should also remember that nuclear medicine cannot survive in a vacuum. We must support our professional societies and have ongoing representation at all levels of government. Membership in the American Medical Association, the Society of Nuclear Medicine, the American College of Nuclear Physicians, the American College of Radiology, and the Radiological Society of North America all help strengthen our voice at the state and national levels. We must continue to effectively present our specialtys positions to the various state and federal agencies that regulate our practice. We must demand high quality studies from our peers and continue to be advocates for our patients.

Bone Scanning for Detection of Exercise-Induced Musculoskeletal Injury.

In brief: Bone scans were obtained on 37 entrants in the Western States 100-Mile Endurance Run between 24 hours and one week after the race. Laboratory tests were also performed. The purpose was to determine the degree of muscle and bone damage sustained. The scans of runners who complained of muscle pain showed regions of increased tracer concentration; in most cases the degree of concentration was proportional to the degree of pain experienced. This concentration in the muscle decreased with time after the race-those obtained a week later showed no evidence of abnormality. Enzyme analyses showed markedly increased levels of total CK and CK MB; muscle biopsy specimens indicated myofibrillar lysis and mitochondrial damage.

Dipyridamole-Thallium Cardiac Imaging

Excerpt To the Editor:The recent letter by Friedman and colleagues (1) provides the valuable warning that death may occur after oral administration of dipyridamole. It was unfortunate that permissi...