James E. Seabold

Utility of Tc-99m mebrofenin scintigraphy in the assessment of infantile jaundice.

Technetium-99m mebrofenin hepatobillary excretory patterns were assessed in 36 infants with hyperbilirubhnemia. Phenobarbital was administered to 22 patients before imaging. Final diagnoses included: intrahepatic chotestasis (14 patients), neonatal hepatitis (nine patients), biliary atresia (eight patients), alpha-1-antitrypsin deficiency (two patients), Ategilles syndrome (two patients), and cystic fibrosis (one patient). No patient with biliary atresia showed bowel activity by 24 hours. Of the 28 infants without biliary atresia, 23 (82%) had bowel activity visualized by 6–8 hours and 26 (90%) had bowel activity by 24 hours. Two had no bowel activity at 24 hours: one had cystic fibrosis and one had neonatal hepatitis. Of the 26 patients with bowel visualization, the time to visualize bowel did not differ between patient groups with and without phenobarbital induction. All of the patients with hepatitis, including those with marked dysfunction, showed good hepatic uptake. Mebrofenin scintigraphy is an important imaging technique in the diagnostic evaluation of infants with hyperbilirubinemia. In addition to biliary atresia, intrahepatic chotestasis due to cystic fibrosis and severe neonatal hepatitis may also cause bowel nonvisualization up to 24 hours. The results of this study suggest phenobarbital induction may not be needed when Tc-99m mebrofenin scintigraphy is used for the assessment of infantile jaundice.

Tc-99m MIBI scintigraphic detection of metastatic insular thyroid carcinoma.

Thallium-201 and, recently, Tc-99m MIBI have been used in conjunction with I-131 scintigraphy for follow-up of patients with well-differentiated thyroid cancer. Insular carcinoma of the thyroid is a fairly aggressive thyroid neoplasm that is believed to arise from follicular cells and usually concentrates I-131. The authors report a patient with recurrent insular thyroid carcinoma in whom bilateral adrenal and lung metastatic lesions developed 3 years after ablative I-131 therapy for cervical lymph node and skeletal metastases. Tc-99m MIBI planar and SPECT images demonstrated these new lesions better than pretherapy I-131 scintigraphy and affords an imaging technique for post-I-131 therapy follow-up that does not require withholding thyroid hormone suppression.

Indium-111 platelet scintigraphy and two-dimensional echocardiography for detection of left ventricular thrombus: influence of clot size and age.

Two-dimensional echocardiography and indium-111 platelet scintigraphy were performed on 50 dogs to determine the influence of clot age and size on the detection of experimentally induced left ventricular mural thrombus. Thrombus was induced by apical infarction and injection of a sclerosing agent and thrombin. The animals were classified into four groups according to the time of indium-111 platelet injection after thrombus induction: Group I (17 dogs, 1/2 hour after induction; 3 dogs, before induction), Group II (12 dogs, 24 hours after induction) and Group III (12 dogs, 1 week after induction). In Group IV (six control dogs) apical infarction was produced, but thrombin was not injected; indium-111 platelets were injected 1/2 to 1 hour after infarction. The dogs were studied by indium-111 platelet scintigraphy and by two-dimensional echocardiography 1/2 to 5 hours (Group I) and 1 to 5 and up to 72 hours (Groups II to IV) after platelet administration and before death was induced. Two-dimensional echocardiography showed the best overall sensitivity for detection of acute thrombus (97%; 29 of 30). The sensitivity of indium-111 platelet scintigraphy was 86% (18 of 21) for clots greater than or equal to 0.08 ml in size, and 67% (20 of 30) for detection of all clots. Thrombus did not form in 14 dogs of Groups I to III and in 6 of 6 control dogs. The specificity of scintigraphy was 100% (20 of 20) compared with 80% (16 of 20) for echocardiography. Echocardiography was more sensitive than scintigraphy for detecting very small clots in this experimental model.(ABSTRACT TRUNCATED AT 250 WORDS)

Lidocaine and dextran sulfate inhibit leukocyte accumulation but not postischemic contractile dysfunction in a canine model

Leukocytes have been implicated as a possible factor in the pathogenesis of postischemic contractile dysfunction, probably through the release of oxygen free radicals. Lidocaine and dextran sulfate are known to inhibit leukocyte adherence to endothelial cells in vitro and in vivo. In an acute open-chest canine model both agents were found to inhibit the augmented accumulation of indium-111-labeled leukocytes in briefly ischemic and subsequently reperfused myocardium. Pharmacologic inhibition of leukocyte accumulation by lidocaine and dextran sulfate, however, was not associated with improvement in postischemic contractile dysfunction.

Colonic localization of indium-111 labeled leukocytes in active Behcet's disease.

A patient with known Behcets disease demonstrated intense colonic localization of In-111 labeled leukocytes. Gastrointestinal involvement had not been previously manifested, but extensive colonic inflammation was documented by endoscopy. This case illustrates the utility of In-111 labeled leukocyte imaging for detecting active bowel disease in a debilitated patient with documented Behcets vasculitis.

Colonic localization of labeled leukocytes in critically ill patients. Scintigraphic detection of pseudomembranous colitis.

This study assesses the causes of colonic localization of labeled white blood cells (WBCs) in critically III patients who had undergone leukocyte scintigraphy for suspected infection. Forty-two patients showed abdominal or pelvic WBC localization; 20 of these had a pattern of colonic localization, and some also showed a pattern of small bowel activity. Eight of the 20 patients had documented gastrointestinal bleeding. White blood cell scintigraphy in these eight patients showed a pattern of multlfocal and/or regional bowel activity that changed in intensity and location from early (3–5-hour) to delayed (18–28-hour) images, in contrast, 5 of the 6 patients with documented pseudomembranous colitis (PMC) showed intense WBC localization involving most of the colon. In 3 of these 5 patients, early and delayed images were acquired and showed a relatively constant pattern of WBC localization. The sixth PMC patient had been treated with vancomycin before leukocyte scintigraphy and showed minimal distal small bowel activity on early images and only mild regional colonic activity on delayed images. As in the patients with gastrointestinal bleeding, the remaining six patients showed either focal or regional activity of variable intensity that changed over time. In critically III patients, gastrointestinal bleeding and PMC accounted for 14 of the 20 patients in which labeled leukocyte scintigraphy exhibited colonic activity. A pattern of diffuse, Intense colonic radiotracer activity which persists from early to delayed imaging strongly suggests the presence of PMC in this patient population. Diagnostic tests to confirm the presence of Clostridium difficile should be undertaken in critically III patients in whom leukocyte scintigraphy shows diffuse WBC localization involving most of the colon.

HMPAO scintigraphy, MRI, and CT of a vascular fibrous dysplasia of the craniofacial bones.

The authors present the case of a child with a predominantly unilateral craniofacial fibrous dysplasia and a substantial redirection of internal carotid blood flow to the dysplastic bone. The case illustrates the advantages of using multiple imaging modalities in the evaluation of this disorder. CT showed the diagnostic findings of fibrous dysplasia and demonstrated the extent of bony involvement. MRI showed the extent and vascularity of the intradiploic fibrous mass and best demonstrated the distortion of underlying cerebral structures. Tc-99m HMPAO brain scintigraphy demonstrated adequate ipsilat-eral cerebral perfusion, thereby excluding any significant cerebral “steal.”