Thyroid scans yield functional information useful in the differential diagnosis of thyroid nodules and are usually performed with TcO4-99m for its favourable physical properties, availability, low ...cost and good correlation with I123. Cold thyroid nodules are very frequent and generally due to benign diseases. To distinguish the minority representing carcinomas, classes of risk must be selected, according to multiple factors, including external radiation exposure, sex, age, iodine intake and thyroid morphology. These patients will undergo fine needle biopsy which can make the final diagnosis. Its accuracy is often preferred as a first line modality in the diagnostic approach to thyroid nodules. Tumour imaging agents are very useful in the staging and follow-up of thyroid carcinomas, but are rarely needed in the primary diagnosis of the disease.
Pancreatic insulinoma is a small, rare neoplasm; its radical therapy is surgical enucleation or resection. Although clinical diagnosis is simple, instrumental and radiological localization is still ...difficult (occult insulinoma: 10-20%).
The authors present the case of a 71-year-old patient suffering from relapsing vertigo syndrome, derangement and transient lypothymia after strong physical activity. ECG, encephalic and abdominal C.T., eco-color-Doppler of epiaortic vessels failed to identify any pathological features. Laboratory tests only revealed that basal glycemia was always lower than normal. Insulinoma was strongly suspected following the outcome of dosages of insulin and C-peptide in the serum and was confirmed after a supervised fast test (72 h). Once the biochemical diagnosis had been reached an abdominal eco, C.T., a selective and superselective angiography and echo-endoscopy were carried out to locate the tumor site but results were negative. Only somatostatin-receptor scintigraphy with 111 In-octreotide detected a catchment area (diameter: 3 cm) to the right of the hypochondrium, anterior to the kidney and caudal to the left hepatic lobe.
During laparotomy a hand-held gamma detecting probe (C-Trak) was used to detect in situ tumour binding of the radiolabelled octreotide and a neoplasm was identified and enucleated from the pancreatic head (diameter: 7 mm), undistinguishable from the surrounding parenchyma. Postoperative signal checks of the surgical field and of the neoplasm revealed, in the first, the absence of captation and, in the second, maximal captation. Histological findings confirmed the nature of the neoplasm: an insulinoma with a ring pattern. Two years after surgery the patient is in good health, with no signs of relapse.
Radio-guided surgery with labelled octreotide makes it possible to pinpoint small insulinomas, locate occult neoplasm, verify the completeness of surgical excision in the field and in the surgical piece, by comparing the different captation of labelled octreotide and check neoplasm multicentricity and any metastases.
The i.p. delivery of murine monoclonal antibody was compared with i.v. delivery in normal mice and rats, in normal nude mice and in those with i.p. human ovarian carcinoma xenografts. In normal rats, ...all classes of antibodies and antibody fragments evaluated were cleared from the peritoneal cavity at comparable rates. The regional delivery (Rd1) advantage to the peritoneal cavity following i.p. delivery was thus most dependent on the rate of clearance of the antibody or fragment from the blood stream. Determining the exact i.p. delivery advantage was problematic due to the difficulty in reliably obtaining peritoneal fluid later than 9-10 h after i.p. injection in normal animals. During the first 9 h following i.p. injection, the Rd(0-9/0-9) was, for a murine IgG2ak Fab greater than F(ab')2 greater than IgG (at 13.6 greater than 10 greater than 7.9). Two murine IgMs evaluated differed in Rd(0-9) at 27.1 and 9.2 respectively. When blood levels were extrapolated to infinity, these Rd (0-9/affinity) values were considerably lower with the Fab having the highest Rd at 4.67. The i.p. Rd advantage was almost solely due to the i.p. antibody levels seen in the first 24 h after injection, as after that time, blood levels become comparable to those seen following i.v. injection. Normal tissues obtained at sacrifice 5-7 days after i.p. injection. Normal tissues obtained at sacrifice 5-7 days after i.p. or i.v. injection in rats showed comparable levels of radioantibody activity, whether the injection was i.p. or i.v. (except for higher diaphragmatic levels following i.p. delivery). In nude mice with i.p. human-derived ovarian tumors, intact IgG clearance from the peritoneal cavity to the blood was considerably slower than in normal animals, and early i.p. tumor uptake of specific antibody was significantly higher than that following i.v. antibody delivery. With higher early tumor uptake and lower systemic exposure, early tumor/nontumor ratios were significantly greater than those for i.v. delivery, though not beyond 48 h after i.p. injection. This study demonstrates the pharmacokinetic rationale for i.p. monoclonal antibody delivery, especially for agents cleared rapidly from the blood, such as antibody fragments. In addition, definite i.p. delivery benefit for antibody specific to i.p. tumors in the i.p. ovarian cancer system was shown soon after injection. These data regarding i.p. antibody delivery should be useful in rationally planning diagnostic and therapeutic studies involving the i.p. delivery of unmodified and immunoconjugated monoclonal antibodies.
Radioactivity in the colon during 131-I-meta-iodobenzylguanidine (MIBG) scintigraphy may obscure or be mistaken for tumor uptake. Fecal excretion of radioactivity was examined in eight patients ...following therapeutic 131-I-MIBG administration (123-218 mCi, 4.551-8.066 GBq) and was found to be 0.02-1.93% of the administered dose. Semiquantitative grading of colonic activity on scintigraphy was inversely related to fecal excretion. An additional patient with marked colonic activity was studied before and after an enema: all visible gut activity was evacuated. We conclude that radioactivity in the colon seen in 131-I-MIBG scintigraphy is due largely to gut excretion of 131-I and is not due to 131-I-MIBG uptake in the autonomic innervation of the gut. Laxatives and enemas are suggested for patients in which such gut radioactivity may lead to difficulties in interpretation.
Esophageal involvement by scleroderma is frequent. Investigation by manometry or radiography is invasive and nonphysiological. Scintigraphy of the clearance of small radiolabelled liquid boluses in ...the supine position, while sensitive and noninvasive, may also be nonphysiological and does not allow the simultaneous determination of gastric emptying. We thus studied the esophageal clearance of a semisolid test meal ingested in the upright position. Forty-seven patients with scleroderma and 24 with Sjogren's syndrome were compared with ten normal controls and ten patients with gastric emptying abnormalities but no esophageal involvement. Results of scintigraphy were also correlated with manometry and contrast radiography. Quantitative evaluation of esophageal tracer retention at ten minutes postingestion was: (mean +/- SD), 2.8 +/- 1.0% in normals, 2.9 +/- 0.9% in gastric dysmotility, 4.8 +/- 2.9% in Sjogren's syndrome, and 22.3 +/- 25.0% in scleroderma; similar results were found at 20 and 60 minutes. The T 1/2 of gastric emptying was 47.1 +/- 5.7 minutes in normals, 95.9 +/- 25.3 minutes in gastric dysmotility, 62.9 +/- 19.5 minutes in Sjogren's syndrome, and 52.9 +/- 13.5 minutes in scleroderma. We conclude that esophageal clearance of a semisolid test meal is a sensitive index of esophageal dysmotility and correlates well with results from manometry and contrast radiography but is noninvasive and quantifiable. The simultaneous measurement of gastric emptying is also possible in many cases.
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