Differentiation of malignant and benign solitary thyroid nodules using 30- and 120-minute tc-99m MIBI scans.

Technetium-99m methoxy isobutylisonitrate (MIBI) has been found to be taken up by various tumors, including thyroid cancer. We prospectively evaluated 77 patients with cold thyroid solitary nodules on Tc-99m pertechnetate scintigraphy to evaluate the diagnostic value of Tc-99m MIBI scintigraphy. The aim of this study was to find out if thyroid nodules can be characterized on the basis of retention of MIBI and whether preoperative evaluation of malignancy is possible using this method. Single injection, dual-phase (30 and 120 minutes) thyroid scintigraphy using Tc-99m MIBI was performed in all these patients. In the following days and weeks, all patients underwent surgery. Using the 120/30-minute thyroid lesion to background radiouptake ratio (RUR), malignant and benign thyroid nodules could be separated with a sensitivity, specificity, and positive predictive value of 84.4%, 95.45%, and 93.33%, respectively. The mean RUR for malignant thyroid lesions was found to be 1.57+/-0.32, whereas for benign lesions, the ratio was significantly lower, 0.32+/-0.19. In conclusion, fine needle aspiration cytology along with the 120/30 minutes Tc-99m MIBI scintigraphy ratio appears to be useful in the preoperative assessment of solitary thyroid nodules.

Tc-99m Infecton scan in possible pelvic inflammatory disease.

Tc-99m Infecton imaging was used to examine patients thought to have pelvic inflammatory disease (PID) based on clinical and sonographic findings. Twenty-one patients with PID had Tc-99m Infecton scans. Eleven patients underwent a second radionuclide scan after 1 month of antibiotic treatment. The diagnosis of PID was confirmed by laparoscopy in one patient who was later found to have a tubercular infection. In the remaining patients, the diagnosis was based on uterine tenderness, fever and lower abdominal pain that responded to antibiotics, and ultrasound findings. These patients had infection of the uterus, fallopian tubes, the cul-de-sac, or all of these. The Tc-99m Infecton scan appears to be useful in the diagnosis of possible PID and is recommended after a complete course of antibiotics for monitoring treatment response.

Tc-99m dextran: a new and sensitive general purpose scintigraphic agent for diagnosing intestinal inflammation.

PURPOSE: This feasibility study was undertaken to compare the sensitivity of Tc-99m dextran with that of Tc-99m human immunoglobulin G to diagnose ulcerative colitis, and to explore its possible role in disease follow-up. MATERIALS AND METHODS: Twenty-six patients with active disease and six patients in remission underwent serial Tc-99m dextran scanning for as long as 3 hours or more after injection. Eight of the patients with active disease also underwent Tc-99m human immunoglobulin G imaging. RESULTS: Twenty-four of 26 (92%) patients with active ulcerative colitis had a positive result of the Tc-99m dextran study, mainly within 1 hour. In comparison, Tc-99m human immunoglobulin G accumulated abnormally in four of eight (50%) patients and had a relatively poor target localization with high persisting background even after 6 hours. Four of the six patients in remission still had a positive result of the dextran scan, but the abnormal uptake was less than that in the patients with active disease. The disease has recurred already in one of these patients. A patient with pancolitis who was receiving steroid enema therapy had intense uptake of Tc-99m dextran in the ascending colon, probability because it was outside the range of the enema. CONCLUSIONS: Tc-99m dextran is a sensitive and cost-effective agent to diagnose ulcerative colitis, and it may have a role in disease follow-up.

Delayed Tc-99m citrate scintigraphy in the evaluation of palpable breast masses.

The aim of this study was to evaluate the potential of Tc-99m citrate as a new tumor-localizing agent in palpable breast masses. Scintimammography was performed in 43 female patients. Of these, 10 women (group A) were considered to be healthy with no palpable breast masses, and the remaining 33 patients (group B) had palpable breast masses. All patients with palpable breast masses underwent fine-needle aspiration cytology and subsequent biopsy within 2 weeks of the study. Nine patients had a primary malignant lesion of the breast, whereas 24 patients had benign disease. The patients with breast cancer underwent surgery, and subsequently a histopathologic diagnosis was made. Sensitivity, specificity, and accuracy values obtained in our study were 87%, 100%, and 90%, respectively. Scintimammograms were performed in these patients up to 24 hours. Initial uptake at 1 and 3 hours was noted in all the breast masses. However, benign masses did not show persistence of tracer uptake at 24 hours, whereas those that were malignant continued to show persistent radionuclide concentration. Thus, the uptake and outflow pattern seemed to differentiate benign breast disease from breast cancer. The study shows the potential of Tc-99m citrate for imaging and evaluating breast masses.

Spontaneous perforation of the gallbladder during infancy diagnosed on hepatobiliary imaging.

Spontaneous gallbladder perforation is a very rare condition in infants. Most gallbladder perforations occur in adults, frequently due to trauma. Ultrasound, peritoneal lavage, and retrograde cholangiography may give indirect evidence of the possibility of this condition. There is no definitive diagnostic modality that can definitely determine the diagnosis in such cases. A case of gallbladder perforation with localized biliary ascites detected on radionuclide hepatobiliary imaging is presented.

Scintiscan demonstration of localized bowel loop inflammation. Comparison of Tc-99m dextran, Tc-99m citrate, and Tc-99m human immunoglobulin G.

A 60-year-old man with localized small bowel inflammation underwent abdominal scintigraphy with Tc-99m human polyclonal immunoglobulin G and two experimental inflammation-seeking agents, Tc-99m dextran and Tc-99m citrate. The abnormal loop was visualized in all the three studies. Additionally, the Tc-99m dextran study revealed exudation and luminal transit of the tracer suggestive of regional protein-losing enteropathy. The authors conclude that Tc-99 dextran and Tc-99 citrate are clinically suitable inflammation-seeking agents that need further evaluation, especially for locating abdominal inflammations.

Radiolabeled denatured RBC scintigraphy in autologous splenic transplantation.

An 18-year-old man underwent surgery for blunt abdominal trauma requiring a total splenectomy. Heterotopic splenic autotransplantation was done in the omentum. Immediate platelets counts, cell morphology, and serum immunoglobulin levels were suggestive of impaired splenic function. Radiolabeled denatured RBC splenic imaging showed evidence of functioning autotransplanted splenic tissue in the omentum. The blood parameters were found to be normal 4 weeks after transplant. Radionuclide denatured RBC imaging has been found to be useful in the localization of functional autotransplanted splenic tissue.

Evaluation of the healing process in fractures using early and delayed bone scanning.

Fifty-two fracture sites were evaluated by bone scintigraphy after acquiring similar views of the lesions at 4 and 24 h following technetium-99m methylene diphosphonate administration. After calculating 24/4 h radio-uptake ratio (RUR) and using 1.15 as the critical point of separation, fresh healing lesions could be separated from old healed fractures persisting as 'hot spots' with a sensitivity of 100% and specificity of 82%. The 24/4 h RUR technique is a new approach in measuring the osteoblastic activity at the lesion site. The technique appears to have clinical significance in the detection and follow up of the healing status of occult fractures where radiological procedures are of limited value.

Differentiation of malignant and degenerative bone lesions using dexamethasone interventional 3- and 24-hour bone scintigraphy.

Seventy-seven adult patients with suspected skeletal metastases were divided into two groups. In group A (n = 30), following intravenous administration of 20 mCi (740 MBq) of technetium-99m methylene diphosphonate (99mTc-MDP), 3- and 24-h scintigraphy of bone lesions was performed. The 24/3 h lesion to bone background radiouptake ratio (RUR) was calculated for each lesion. In group B (n = 47), the same procedure was followed with dexamethasone intervention (10 mg in 24 h) following the 3-h acquisition. In group A, after determination of the critical point, malignant and degenerative bone lesions could be separated with a sensitivity, specificity and accuracy of 0.76, 0.72 and 0.73, respectively. The mean RUR of the malignant lesions was 1.20 +/- 0.23, and that of the benign lesions, 0.95 +/- 0.15. In group B cases, significantly increased sensitivity, specificity and accuracy of 0.87, 0.94 and 0.92, respectively, were found (P < 0.001). The mean RUR of the malignant lesions was 1.48 +/- 0.34, and that of degenerative lesions, 0.88 +/- 0.19. Dexamethasone interventional bone scintigraphy seems to be a new cost-effective method for differentiating malignant from degenerative bone lesions using the RUR.

24 hour/3 hour radio-uptake technique for differentiating degenerative and malignant bony lesions in bone scanning.

Differentiating bony metastases from degenerative lesions is of great importance to the oncologist. Routine bone scanning using technetium-99m methylene diphosphonate is the investigation of choice for detecting bony lesions, but its specificity is low. Using the difference in radio-uptake behaviour of metastatic and degenerative lesions as the criterion, a 24/3 h radio-uptake, lesion to non-lesion ratio was used to separate out the two types of lesions. Radio-uptake ratio (RUR) distribution curves of malignant and degenerative lesions were found to be significantly different (P < 0.001). Taking 1.12 as the critical point, RUR of malignant lesions was found to be more than the critical point, and that of degenerative lesions was found to be less than the critical point. Sensitivity, specificity and accuracy were found to be 68%, 80% and 74%, respectively.