The rim sign in acute cholecystitis. Comparison of radionuclide, surgical, and pathologic findings

Nonvisualization of the gallbladder associated with the rim sign of enhanced pericholecystic hepatic activity has been established as a useful and highly specific sign of acute cholecystitis. This study's purpose was to determine the pathophysiologic cause of the rim sign. Thirty-seven surgery-bound patients with a clinical diagnosis of acute cholecystitis were studied. A group of 20 patients with a definite rim sign were compared to a group of 17 patients without a rim sign; all with nonvisualization of the gallbladder. Radionuclide, surgical, and pathologic findings were correlated. In patients with the rim sign and in those without the rim sign, microscopic review of all surgical specimens revealed transmural reaction of the gallbladder wall in 95% and 59% of cases, respectively. The surgeon found inflammation extending beyond the gallbladder wall in 75% of rim sign cases, but in only 35% of case without the rim sign. Liver tissue was attached to the gallbladder specimen in three cases, and the findings support the association of hepatic inflammation with the presence of a rim sign. Pathologic correlation and surgical evidence suggest that the rim sign is caused by the spread of inflammation through the gallbladder wall and into adjacent liver tissue. Transmural reaction is required before the inflammatory process can reach the liver. A high-count, high-intensity technique seems to best demonstrate the rim sign. Once demonstrated, further delayed imaging is unnecessary.

Thallium scintigraphy in the evaluation of mass abnormalities of the breast

Palpable mass abnormalities of the breast are often difficult to evaluate mammographically, especially in patients with fibrocystic change and dense breasts. The current study evaluates 201TI scintigraphy as a potential test in detecting malignancy and in differentiating malignant from benign masses. Eighty-one female patients underwent thallium scintigraphy of the breast because of palpable breast masses. An additional 30 females with no palpable breast abnormalities were also studied using 201TI. Of 44 patients with palpable breast carcinomas, 42 carcinomas (96%) were detected using 201TI scintigraphy. Three of three patients had other primary breast malignancies that were also detected. In contrast, 19 patients with palpable breast abnormalities shown on biopsy to be benign fibrocystic disease processes were not detectable on thallium studies. Of two patients with fat necrosis, none were detectable. Three of 13 patients had adenomas of the breast (23%) that were detected. The three detectable adenomas were all highly cellular. The smallest detectable carcinoma was an adenocarcinoma measuring 1.3 x 1.1 x 0.9 cm. Thallium-201 scintigraphy of palpable breast lesions is an effective test for evaluation of palpable masses. Sensitivity for detection of malignant masses greater than 1.5 cm is high. Highly cellular adenomas, however, may demonstrate significant 201TI uptake. Benign fibrocystic disease is not detectable with thallium scintigraphy. Thallium scintigraphy of breast lesions is an effective means of differentiating benign from malignant lesions.

False-positive iodine-131 body scan caused by a large renal cyst

Focal I-131 accumulation is generally a reliable indicator of functioning thyroid tissue or a differentiated thyroid cancer metastasis. Normal accumulation of activity may be seen in areas such as the intestinal tract, liver, and salivary glands. This report describes a patient with significant accumulation of I-131 in the right upper quadrant of the abdomen. The abnormality, first thought to represent metastatic thyroid carcinoma, was subsequently proven to be accumulation within a large renal cyst.

Regional comparison of technetium-99m DTPA aerosol and radioactive gas ventilation (xenon and krypton) studies in patients with suspected pulmonary embolism

The regional distribution of [99mTc]DTPA aerosol was compared with that of 133Xe (n = 30) and krypton (n = 24) in a group of patients with suspected pulmonary embolism. All patients had an aerosol study using a recently available commercial generator system, a ventilation study with one of the gases, and perfusion imaging. Regional information was assessed visually on xenon, krypton, and aerosol studies independently by considering each lung as three equal-sized zones. In addition, gas ventilation findings peripheral to regions of aerosol turbulence ("hot spots") were evaluated. Only 64% of the zones were in complete agreement on xenon and aerosol. Most of the discordance between xenon and aerosol was accounted for by minor degrees of 133Xe washout retention in zones that appeared normal in the aerosol study. An agreement rate of 85% was noted between 81mKr and aerosol regionally. The regions of discordance between aerosol and gas studies, however, usually were associated with unimpressive perfusion defects that did not change the scintigraphic probability for pulmonary embolism in any patient. Regarding zones of aerosol hyperdeposition, 76% had associated washout abnormalities on xenon; however, there was no correlation between the presence of these abnormalities or perfusion abnormalities. The results confirm the high sensitivity of 133Xe washout imaging, but suggest that radioaerosol imaging will detect most parenchymal abnormalities associated with perfusion defects of significance.

Evaluation of low-dose radioiodine ablation therapy in postsurgical thyroid cancer patients

Nineteen patients with differentiated thyroid carcinoma were given low dose (30 mCi) radioiodine therapy for the ablation of residual thyroid tissue following total thyroidectomy. Using 5- to 10-mCi diagnostic I-131 scans, ablation was achieved in two of 19 patients following the first low dose and three of 12 patients following the second low-dose therapy. The ablation response was 53% (ten of 19) following one large dose (100 mCi) in another concurrent group of 19 patients. The ablation response following the first low dose when compared with the first high-dose therapy was significantly lower (P = 0.015). The combined ablation response following first and second low doses (five of 14) when compared to a single large dose was not significantly different (P = 0.534). The use of low-dose-I-131 therapy, although not as effective as large dose therapy, may be warranted in patients resistant to entering the hospital for therapy. However, ablation as defined by a five- to ten-mCi I-131 scan can be expected to occur in only one third of the patients after two attempts at ablation, while a single 100-mCi regimen can be successful in achieving ablation in over one half of the patients after the first attempt.

Treatment rationale in thyroid carcinoma. Effect of scan dose

The authors have previously shown that the definition of ablation of thyroid tissue in patients treated with thyroidectomy and radioiodine (I-131) for thyroid carcinoma depends upon the dose of I-131 used to scan the patient. The therapeutic response to I-131 therapy was evaluated in a group of ten differentiated thyroid cancer patients who had a negative 2-mCi (-2 mCi) diagnostic study, but had a positive 10-mCi (+10 mCi) diagnostic study (group 1) during their follow-up evaluation. These results were compared to another group of ten differentiated thyroid cancer patients who received I-131 ablation therapy based on a positive 2-mCi (+2 mCi) I-131 scan (group 2). Six patients in group 1 and eight in group 2 had improvement or ablation of residual tissue based on the 10-mCi scan following therapy. The difference in response between the two groups was not statistically significant (P = 0.63) by two-tailed Fisher's exact test, indicating that even patients with -2-mCi, but +10-mCi scans may respond to I-131 therapy. Whether the large dose therapy makes any impact on the clinical outcome has not been answered by this study.

Correlation of thyroglobulin measurements and radioiodine scans in the follow-up of patients with differentiated thyroid cancer

Correlation of radioiodine (131I) scans and serum thyroglobulin (Tg) concentrations were performed in the follow-up of 85 differentiated thyroid cancer patients who had undergone total thyroidectomy. Tg results were also compared with the control group of 33 thyroidectomized patients with no evidence of thyroid carcinoma and normal values for Tg established. Excellent correlation between Tg and scans was noted in patients with scan evidence of metastasis distant from the neck. Poor correlation was present in patients with scan evidence of local neck metastasis only, thyroid bed activity, and those with mediastinal activity. In addition, in 8% of the patients, the Tg assay could not be performed because of interfering antibodies. The conclusion is that elevated Tg concentration is a good indicator of metastasis outside of the neck as detected by 131I scans. Caution should be used when Tg alone is used in evaluating local neck metastasis demonstrated on scans. The significance of mediastinal activity warrants further investigation.

Scintigraphy of gastrointestinal hemorrhage: superiority of 99mTc red blood cells over 99mTc sulfur colloid

The relative efficacy of 99mTc sulfur colloid and in vitro-labeled 99mTc red blood cells in detecting and localizing gastrointestinal hemorrhage was evaluated in a prospective tandem study of 100 patients referred for suspicion of gastrointestinal tract hemorrhage. Thirty-eight true-positive scintigrams were obtained with 99mTc red blood cells, whereas 99mTc sulfur colloid detected only five sites of hemorrhage. Scintigraphic findings were corroborated by clinical, endoscopic, arteriographic, and surgical findings. 99mTc red blood cells were clearly superior, with a sensitivity of 93%, specificity of 95%, and overall accuracy of 94% in detecting and localizing gastrointestinal hemorrhage.

Gallium scintigraphy in bronchogenic carcinoma. The effect of tumor location on sensitivity and specificity

Fifty-one patients with primary lung cancer were evaluated using 67Ga citrate scintigraphy with respect to detection of peripheral primary, hilar metastasis, and mediastinal metastasis. The results demonstrated the necessity for an understanding of the criteria used in considering the gallium scintigram as either positive or negative, as well as the instrumentation employed in performing the test before any meaningful sensitivity and specificity figures can be derived within a given institution. Only with this understanding can actual strategy for instituting invasive procedures be achieved.

Cholescintigraphy in acute acalculous cholecystitis

Acute acalculous cholecystitis is a relatively rare but potentially lethal condition if not treated promptly. Since stones are not present, diagnostic procedures such as ultrasound or other radiological procedures are frequently not helpful. Tc-99m iminodiacetic acid scan results were analyzed in 11 proven cases of acute acalculous cholecystitis. All had positive tests with nonvisualization of the gallbladder giving a sensitivity of 100%. Tc-99m iminodiacetic acid cholescintigraphy is a highly reliable test and is easily performed even in acutely ill patients and should be the test of choice in all patients predisposed to and suspected of acute acalculous cholecystitis.

Acute gangrenous cholecystitis: radionuclide diagnosis

Radionuclide hepatobiliary imaging is a useful procedure for the diagnosis of acute cholecystitis. Visualization of the gallbladder essentially rules out acute cholecystitis. Nonvisualization suggests acute cholecystitis but may also be associated with chronic gallbladder disease or other conditions. We recently observed five patients in whom a rim of increased parenchymal liver activity was seen adjacent to the gallbladder fossa. All five patients had acute gangrenous cholecystitis. The rim of increased activity appears to be a useful secondary sign of acute cholecystitis.

Liver scintigraphy in colon carcinoma: correlation with modified Duke pathological classification

Hepatic scintigraphy was performed prior to surgical exploration in 89 patients with primary carcinoma of the large bowel. Of these patients, 26% had positive liver scans at the time the diagnosis was established. The presence or absence of liver metastasis by scintigraphic criteria was correlated with surgical findings, a modified Duke pathologic classification, and the presence of tumor markers. The sensitivity of hepatic scintigraphy was 96% and the specificity was 98%. A total of 63% of patients with abdominal lymph node involvement had positive liver scans while 4.6% of patients without lymph node involvement had positive scans. A total of 91% of patients with positive liver scans had positive abdominal nodes. Of 60 patients with normal liver scans, one (1.7%) had hepatic metastasis and 27% had tumor in regional lymph nodes. Hepatic scintigraphy is highly sensitive in detecting liver metastasis from large bowel carcinoma. However, a negative liver scan did not exclude abdominal lymph node spread.

Thallium-201 stress redistribution abnormalities of the right ventricle: a manifestation of proximal right coronary artery stenosis

Thallium imaging in conjunction with electrocardiographic stress testing has become a widely utilized method for evaluating the presence and location of coronary artery disease. The literature has emphasized the appearance of the left ventricle with little mention of the right ventricle. This report presents the initial demonstration of abnormal right ventricular myocardial radionuclide visualization due to right coronary artery stenosis, as exemplified in two patients. In both patients a perfusion defect was documented in the free wall of the right ventricle with early redistribution imaging showing reversibility of these defects. Both patients were found to have proximal stenosis of the right coronary artery at cardiac catheterization. Thereby, the appearance of the free right ventricular wall on thallium imaging may provide useful additional information regarding presence and location of right coronary artery stenosis.

Clinical and parametric evaluation of three large-field-of-view cameras

This paper compares the clinical and parametric performance, at 140 keV, of three different large-field cameras in a single institution. The instruments tested were the Ohio Nuclear 410, Picker 4/15, and Searle LFOV. There were differences noted in both qualitative and quantitative measurements of physical performance, but these differences could not be demonstrated in clinical studies.

Early and delayed Tc-99m glucoheptonate brain scintigraphy: are routine early images indicated?

Both early and delayed Tc-99m glucoheptonate brain images were evaluated in 859 patients in order to determine whether the early imaging with this agent is clinically useful. The results suggest that the early brain images are inferior to the delayed ones in detecting CNS lesions. Use of both, however, may help to differentiate skull or scalp abnormalities from true lesions of the brain.