Bruce R. Line

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.

The clinical evaluation of patients with subclinical hyperthyroidism and free triiodothyronine (free T3) toxicosis

PURPOSEnTo develop a strategy to identify cases of endogenous subclinical hyperthyroidism and free triiodothyronine (free T3) thyrotoxicosis in otherwise healthy ambulatory patients.nnnPATIENTS AND METHODSnIn a retrospective study we reviewed the records of ambulatory patients who had thyroid stimulating hormone (TSH) levels determined between October 1, 1991 and August 31, 1992. Each patient also had a simultaneous free thyroxine (free T4) measurement. Patients were excluded from consideration if they had active, concurrent non-thyroidal illness, psychiatric disease, known hypothalamic/pituitary lesions, were under treatment for hyper- or hypothyroidism, were on drugs known to affect TSH levels, or were pregnant. Patients without exclusions were diagnosed with free T3 toxicosis if they had: (1) a markedly subnormal TSH level (less than or equal to 0.1 mU/L), (2) a normal free T4, (3) a normal total T3, (4) evidence of a primary thyroid abnormality (e.g., autonomous function on a thyroid scan), and (5) an elevated free T3 level by tracer equilibrium dialysis. Patients meeting conditions 1-4, but with normal free T3 levels, were considered to have subclinical hyperthyroidism.nnnRESULTSnOne thousand twenty-five patients had TSH and simultaneous free T4 determinations, and 148 of these had markedly subnormal TSH but normal free T4 levels. Three patients met the criteria for free T3 toxicosis and three had subclinical hyperthyroidism. All six patients had either multinodular glands or a single nodule on thyroid exam. Four patients were treated with radioactive iodine or surgery, resulting in reversal of the TSH suppression in three cases.nnnCONCLUSIONnApparently healthy ambulatory patients with subnormal TSH levels should be worked up with measurements of free T4 and total T3. If these are normal, a T3 level (by tracer equilibrium dialysis) be obtained to distinguish subclinical hyperthyroidism from overt free T3 toxicosis. A thyroid scan and radioiodine uptake measurement can be obtained to substantiate the diagnosis. Some patients with these conditions will benefit from treatment.

Bone scintigraphy of calciphylaxis : A syndrome of vascular calcification and skin necrosis

Abstract: Calciphylaxis is a highly morbid syndrome of vascular calcification and skin necrosis, the pathophysiology of which remains largely elusive. We report a patient with end-stage renal disease and multiple painful skin lesions who underwent a bone scan for extremity pain. Increased tracer accumulation was seen in the subcutaneous tissues of the trunk and lower extremities. In this case, the bone scan aided in the diagnosis and treatment of calciphylaxis for a patient who experienced a relatively short hospital stay.

Carcinoembryonic antigen immunoscintigraphy complements mammography in the diagnosis of breast carcinoma

An adjunctive noninvasive test that is predictable and highly specific for breast carcinoma would complement the high false‐positive rate of mammography in certain patients.

Clinical production of pharmaceutical grade Tc-99m dextran 70 for lymphoscintigraphy

Lymphoscintigraphy is an established means to determine the lymphatic drainage patterns from malignant tissues and edematous extremities. Unfortunately, there are no commercially available dedicated radiopharmaceuticals labeled for use in lymphoscintigraphy studies. The authors report a simple way to extemporaneously compound pharmaceutical-grade Tc-99m dextran 70 to meet this need. Pharmaceutical-quality Tc-99m dextran 70 injection is prepared by a simple rapid method from drug intermediates that are marketed as parenteral drug products. The radiolabeling process yields a product of high radiochemical purity, with good in vitro and in vivo stability. The authors illustrate the use of this product in a patient with melanoma to show the lymphatic drainage pattern before surgery. The method described permits rapid compounding of Tc-99m dextran 70 injection from drug components that are intended for parenteral administration. Tc-99m dextran 70 provides the option of performing lymphoscintigraphy in any clinical nuclear medicine setting.

Cardiopulmonary thromboembolism detected by Tc-99m MH-1 antifibrin antibody.

A patient with shortness of breath had a high probability lung scan for pulmonary embolism, but no obvious embolic source. Whole-body scintigraphy using Tc-99m labeled Fab antifibrin monoclonal antibody showed large central pulmonary emboli as well as tracer uptake in the right atrium and aortic arch. No lower extremity clot was detected. This case shows significant differences in the appearance of pulmonary embolism as assessed by direct clot and ventilation-perfusion scintigraphy. It shows the importance of the heart as the origin of pulmonary emboli and the utility of direct thrombus visualization.

Bone scan of advanced polycythemia vera with malignant transformation

A 69-year-old man with polycythemia vera and myelofibrosis was seen with a 2-week history of increasing arm pain. A bone scan showed diffuse prominence of the long bones, especially in the metaphyseal and epiphyseal regions of the lower extremities. There was relative prominence of the proximal right humerus that suggested the presence of a malignant process in addition to marrow space expansion secondary to myelofibrosis. An MRI of the right upper extremity showed a permeated lesion in the proximal right humerus extending into the adjacent soft tissue with a large soft tissue component. At surgery, a biopsy was followed by placement of a humeral rod. The morphologic features of the tumor together with CD34 positivity were consistent with a granulocytic sarcoma. This is the first reported case of bone scintigraphic findings in advanced p. vera with myelofibrosis and malignant transformation. The case illustrates the scintigraphic appearance of extensive expansion of the marrow and suggests the importance of vigilance for relatively subtle changes of complicating malignancies.

Nuclear medicine information management systems

There are good arguments for considering a computer system to improve timeliness and quality of patient care, enhance the format of clinical reports, and strengthen management controls for the containment of health care costs. A nuclear medicine information management system serves to fill these needs. Receptionists access the system to schedule patient studies, log patient data, and generate examination records. Secretaries transcribe and print clinical reports. Film library staff locate patient films and keep track of borrowed studies. Technologists produce study work sheets, record quality assurance information, and process the examination results. Staff preparing radiopharmaceuticals use the system to receive and inventory tracer stocks, track preparation and dispensing activities, and to keep records for external review. Clinicians use it to look up old study results and record their study impressions. Managers access statistical reports, billing information, and resource utilization data. This review describes an information management system as implemented in a nuclear medicine clinic. Software applications for patient scheduling, radiopharmacy, film management, report generation, quality assurance, and inventory control are described as implemented on a variety of academic and commercial systems. Hardware architectures and the issues surrounding system specification and installation are explored.

A pharmaco-scintigraphy study of riboflavin 5'-phosphate sodium capsules (1 vs. 4)

Abstract The comparative in-vivo disintegration, gastric emptying and bioavailability of 41 mg radiolabeled riboflavin 5′-phosphate sodium capsules administered as a single hard gelatin capsule or as four capsules was evaluated in human subjects. A total of 41 mg of riboflavin 5′-phosphate sodium and 7 MBq of technetium sulfur colloid were incorporated in a single gelatin capsule or the same dose was administered in four capsules. A randomized crossover design was conducted in eight subjects under fasting conditions. Capsule disintegration and gastric emptying was measured by γ scintigraphy and the relative amount of riboflavin excreted in the urine was measured by HPLC. The in-vivo disintegration time and gastric emptying of the four capsules was significantly faster than for the one capsule. The bioavailability of the four capsule regimen was 16.5 versus 11.2% for the one capsule. The amount of riboflavin excreted in the urine in the 0–2 h interval was significantly greater for the four versus one capsule. The in-vivo performance of one 41 mg riboflavin 5′-phosphate sodium capsule is significantly different than the equivalent dose administered in four capsules. Further studies are needed to understand the underlying mechanism for the difference between the regimens.

Phantom infection in asymptomatic vessels.

Tc-99m autologous-labeled leukocyte scintigraphy is widely used to detect sites of abscess and infection. The authors report two cases in which persistent tracer uptake was found in patent, non-infected, asymptomatic vessels. One was in a lower extremity varicosity in a patient being screened for inflammatory disease of the opposite ankle. The other was in a prosthetic aorta-to-right common femoral artery by-pass graft, that was found to be noninfected by intraoperative swab biopsy. Persistent uptake in patent, noninfected vessels has not previously been reported. The cause of this persistent margination of radiolabeled white blood cells is unknown. These cases suggest the need to consider a noninfectious etiology for white cell localization in varicosities and by-pass grafts